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  • 1.
    Aevan, Nadjib Danial
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    MDO Framework for Design of Human PoweredPropellers using Multi-Objective Genetic Algorithm2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis showcases the challenges, downsides and advantages to building a MultiDisciplinary Optimization (MDO) framework to automate the generation of an efficientpropeller design built for lightly loaded operation, more specifically for humanpowered aircrafts. Two years ago, a human powered aircraft project was initiatedat Linköping University. With the help of several courses, various students performedconceptional design, calculated and finally manufactured a propeller bymeans of various materials and manufacturing techniques. The performance ofthe current propeller is utilized for benchmarking and comparing results obtainedby the MDO process.The developed MDO framework is constructed as a modeFRONITER project wereseveral Computer Aided Engineering softwares (CAE) such as MATLAB, CATIAand XFOIL are connected to perform multiple consequent optimization subprocesses.The user is presented with several design constraints such as blade quantity,required input power, segment-wise airfoil thickness, desired lift coefficientetc. Also, 6 global search optimization algorithms are investigated to determinethe one which generate most efficient result according to several set standards.The optimization process is thereafter initialized by identifying the most efficientchord distribution with a help of an initial blade cross-section which has been previouslyused in other human powered propellers, the findings are thereafter usedto determine the flow conditions at different propeller stations. Two different aerodynamicoptimized shapes are generated with the help of consecutively performedsubprocesses. The optimized propeller requires 7.5 W less input power to generatenearly equivalent thrust as the original propeller with a total efficiency exceedingthe 90 % mark (90.25 %). Moreover, the MDO framework include an automationprocess to generate a CAD design of the optimized propeller. The generatedCAD file illustrates a individual surface blade decrease of 12.5 % compared tothe original design, the lightweight design and lower input power yield an overallpropulsion system which is less tedious to operate.

    Download full text (pdf)
    MDO Framework for Design of Human Powered Propellers using Multi-Objective Genetic Algorithm
  • 2.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Melin, Tomas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Staack, Ingo
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Multidisciplinary Optimization of Wing Structure Using Parametric Models2013Conference paper (Other academic)
    Abstract [en]

    Aircraft design is an inherently multidisciplinary activity that requires integrating different models and tools to reach a well-balanced and optimized product. At Linköping University a design framework is being developed to support the initial design space exploration and the conceptual design phase. Main characteristics of the framework are its flexible database in XML format, together with close integration of automated CAD and other tools, which allows the developed geometry to be directly used in the subsequent preliminary design phase. In particular, the aim of the proposed work is to test the framework by designing, optimizing and studying a transport aircraft wing with respect to aerodynamic, geometry, structural and accessability constraints. The project will provide an initial assessment of the capability of the framework, both in terms of processing speed and accuracy of the results.

  • 3.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A framework for integrated terminal airspace design2019In: Aeronautical Journal, ISSN 0001-9240, Vol. 123, no 1263, p. 567-585Article in journal (Refereed)
    Abstract [en]

    Route planning and airspace sectorisation are two central tasks in air traffic management. Traditionally, the routing and sectorisation problems were considered separately, with aircraft trajectories serving as input to the sectorisation problem and, reciprocally, sectors being part of the input to the path finding algorithms. In this paper we propose a simultaneous design of routes and sectors for a transition airspace. We compare two approaches for this integrated design: one based on mixed integer programming, and one Voronoi-based model that separates potential "hotspots" of controller activity resulting from the terminal routes. We apply our two approaches to the design of Stockholm Terminal Maneuvering Area.

  • 4.
    Andersson, Henric
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Herzog, Erik
    Saab Aeronautics, Linköping, Sweden.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Experience from Model and Software Reuse in Aircraft Simulator Product Line Engineering2013In: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 55, no 3, p. 595-606Article in journal (Refereed)
    Abstract [en]

    Context: "Reuse" and "Model Based Development" are two prominent trends for improving industrial development efficiency. Product lines are used to reduce the time to create product variants by reusing components. The model based approach provides the opportunity to enhance knowledge capture for a system in the early stages in order to be reused throughout its lifecycle. This paper describes how these two trends are combined to support development and support of a simulator product line for the SAAB 39 Gripen fighter aircraft.

    Objective: The work aims at improving the support (in terms of efficiency and quality) when creating simulation model configurations. The objective is to increase the level of reuse when combining and customizing models for usage in a range of development and training simulators.

    Method: The research has been conducted with an interactive approach using prototyping and demonstrations, and the evaluation is based on an iterative and a retrospective method.

    Results: A product line of simulator models for the SAAB 39 Gripen aircraft has been analyzed and defined in a Product Variant Master. A configurator system has been implemented for creation, integration, and customization of stringent simulator model configurations. The system is currently under incorporation in the standard development process at SAAB Aeronautics.

    Conclusion: The explicit and visual description of products and their variability through a configurator system enables better insights and a common understanding so that collaboration on possible product configurations improves and the potential of software reuse increases. The combination of application fields imposes constraints on how traditional tools and methods may be utilized. Solutions for Design Automation and Knowledge Based Engineering are available, but their application has limitations for Software Product Line engineering and the reuse of simulation models.

  • 5.
    Andersson, Tobias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    The flight perturbation problem: operational aircraft rescheduling2001Licentiate thesis, monograph (Other academic)
    Abstract [en]

    When there is a perturbation in a carefully planned flight schedule, e.g. an aircraft breakdown, it is important to minimize the negative consequences of this disturbance. In this thesis, a model and a number of solution strategies for the Flight Perturbation Problem is presented. Based on a connection network, a mixed integer multicommodity flow model with side constraints is developed. Cancellations, delays and aircraft swaps, both within the same fleet and between different aircraft types, are used to take care of the perturbation. The model also assures that the schedule returns to normal within a certain time.

    Six different solution strategies arc used to solve the model; the first based on a Lagrangian relaxation of the mixed integer multicommodity flow model. Four strategies are based on Dantzig-Wolfe decomposition and in two of them all feasible points are generated by a tree search algorithm before the master problem is solved, while the other two are column generation based. The last strategy is based on the metaheuristic tabu search.

    The computational tests with real problem data show that the Dantzig-Wolfe based strategies and the tabu search strategy arc very promising, and especially the tabu search strategies could be used in a real problem application that could provide airlines with solutions to complex perturbation problems.

  • 6.
    Anjaneya Reddy, Yuvarajendra
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Master Thesis - Towards a Virtual Climate Chamber: A numerical study using CFD software2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For each generation of electronic equipment there is a trend towards higher power den-sities. Increased heat generation is an undesired consequence that the thermal design unit in a company must handle. The goal of thermal design engineer/unit is to utilizethe same volume to more efficiently transfer more heat from the equipment. This can bedone by exploring more complex and advanced heat sink geometries, optimizing the finshapes and so on. The new prototypes developed will be tested for their reliability and endurance in special chambers called climate chambers, that simulate desired environ-ments. The measurements by thermal design teams in these kind of climate chambers are mainly of outdoor products, whose cooling is based on natural convection. Forcedcooling using fans is optional for these outdoor products.

    The climate chambers in general provides temperature measurement as the outputto the analysis, though there are other important parameters that define the operationalfunctionality of an equipment. The ability to visualize the flow characteristics duringthe process of testing is a valuable aid in the design process. A virtual/CFD form of thephysical climate chamber (CC) would empower the design process, while alleviating theusage of the climate chambers for such analyses. CFD offers a wide range of capabilitiesthat lets the user change the boundary conditions with great ease compared to that ofthe experimental setup.

    The numerical model developed in this thesis project provides results, that help inunderstanding the physics involved in fluid flow inside the physical climate chamber.Turbulence quantification of the flow is the main aim of this thesis project, which wouldbe resourceful in future works. Experiments are conducted inside the climate chamber, in order to aid the construction of numerical model as well as serve as source of vali-dation for the numerical results. Laminar transient case simulations are preferred over use of any turbulence models, to limit any kind of predictions made by these turbulencemodels. Integral length scales and turbulence intensities are compared and reason fordiscrepancies are addressed.

    The results from the comparisons show that, the numerical model emulates physicsof actual flow inside the climate chamber. However, there are many factors that directlyaffect the results, making it difficult to precisely quantify the error, within the time periodof this thesis project.

    Download full text (pdf)
    Towards_A_Virtual_Climate_Chamber-Numerical_Study-Yuvraj_Reddy
  • 7.
    Arjoni, D. H.
    et al.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Rocha, G. C.
    Konatus, São José dos Campo, Brazil.
    Moreira, A. H.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Nicola, R. M.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Oliveira, W. R.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Silva, A. V. S.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Natal, G. S.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Silveira, L.
    NAC, São José dos Campo, Brazil.
    Thomas, E.
    Embraer, São José dos Campo, Brazil.
    Villani, E.
    TA Instituto Tecnológico de Aeronáutica, São José dos Camp, Brazil.
    Trabasso, Luís Gonzaga
    TA Instituto Tecnológico de Aeronáutica, São José dos Camp, Brazil.
    Experimental Evaluation of the Human Performance on a RoboticFlight Simulator based on FOQA Parameters2016In: Proceedings of the Aerospace Technology Congress / [ed] Kaj Lundahl, Roland Karlsson, Björn Jonsson and Knut Övrebö, Stockholm, 2016, Vol. 1, p. 1-11Conference paper (Refereed)
    Abstract [en]

    The SIVOR project, currently being developed by ITA and Embraer, consists of designing andimplementing a high fidelity flight simulator based on the use of COTS industrial robots. The aim of theproject is to provide a cost-efficient and flexible platform that can be used along the design phases of theaircraft. One of the advantages of an industrial robot over the traditional Stewart platform is theavailability of a large workspace, which provides more flexibility for defining the washout filter. Thisfilter converts the aircraft dynamics into robot movements, which has a limited workspace. The mainpurpose of the flight simulator is to provide a motion feeling similar to the one imposed by the aircraftmovements in a real flight. The representativeness of the motion cue is usually evaluated in a qualitativeway by the pilots that fly the simulator. Quantitative methods to evaluate the entire range of actuation of asimulator are complex, inducing tests in fractions of the flight to increase performance. In this work, wediscuss the use of FOQA (Flight Operational Quality Assurance) as an additional quantitative tool for theevaluation of the motion cue in the SIVOR flight simulator. FOQA is a voluntary safety program fromFAA, detailed in AC-120-82. It proposes a set of parameters that can be used by airliners to analyse flightsafety and increase operational efficiency. The verification of FOQA parameters checks whether or notthe pilot complies with the standard operational procedures defined by the airliners and aircraftmanufacturers. The purpose of this work is to analyse whether or not, and to what extent, the FOQAparameters can be used to evaluate the quality of the motion cue of flight simulators. For this purpose, wedefine an experimental procedure that compares flights performed by pilots under different motionmodes. It then calculates a set of behavioural parameters that has been proposed in order to quantify howthe motion affects the inputs of the pilot. The results are submitted to ANOVA statistical analysis thatverifies the relevance of the motion factor. Finally, we discuss the capability of a FOQA basedexperiment to estimate the contribution of the motion to the realism of the flight simulation.

    Download full text (pdf)
    Experimental Evaluation of the Human Performance on a RoboticFlight Simulator based on FOQA Parameters
  • 8.
    Arustei, Adrian
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Development of a System Identification Tool for Subscale Flight Testing2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aircraft system identification has been widely used to this day in applications like control law design, building simulators or extending flight envelopes. It can also be utilized for determining flight-mechanical characteristics in the preliminary design phase of a flight vehicle. In this thesis, three common time-domain methods were implemented in MATLAB for determining the aerodynamic derivatives of a subscale aircraft. For parameter estimation, the equation-error method is quick, robust and can provide good parameter estimates on its own. The output-error method is computationally intensive but keeps account of the aircraft's evolution in time, being more suitable for fine-tuning predictive models. A new model structure is identified using multivariate orthogonal functions with a predicted squared error stopping criteria. This method is based on linear regression (equation-error).

    The code written is flexible and can also be used for other aircraft and with other aerodynamic models. Simulations are compared with experimental data from a previous flight test campaign for validation. In the future, this tool may help taking decisions in conceptual design after a prototype is tested.

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    fulltext
  • 9. Order onlineBuy this publication >>
    Baer, Katharina
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Simulation-Based Optimization of a Series Hydraulic Hybrid Vehicle2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Hybrid transmissions are characterized by their utilization of more than one form of energy storage. They have the potential to help reduce overall fuel consumption and vehicle emissions by providing the possibility of brake energy recuperation and prime mover operation management. Electric hybrids and electric vehicle drives are nowadays ubiquitous, and mechanical energy storage in flywheel has been investigated in the past. The use of fluid power technology with a combustion engine has also been investigated since the late 1970s, and is frequently revisited.

    Hydraulic hybridization is especially attractive for heavy vehicles with frequent braking and acceleration which benefit most from fluid power components’ high power density, typically busses, delivery or refuse vehicles, and vehicles with existing hydraulic circuits and transmissions, such as forest and construction machinery, but have been considered for smaller vehicles as well.

    Due to the characteristic discharge profile of hydraulic energy storage, special attention needs to be paid to control aspects in the design process to guarantee drivability of the vehicle. In this respect, simulation models can be of use in early design process stages for cheaper and faster evaluation of concepts and designs than physical experiments and prototyping, and to generate better understanding of the system studied. Engineering optimization aids in the systematic exploration of a given design space, to determine limits and potentials, evaluate trade-offs and potentially find unexpected solutions. In the optimization of a hydraulic hybrid transmission, the integration of component and controller design is of importance, and different strategies (sequential, iterative, bi-level and simultaneous approaches) are conceivable, with varying consequences for the implementation.

    This thesis establishes a simulation-based optimization framework for a hydraulic hybrid transmission with series architecture. Component and control parameter optimization are addressed simultaneously, using a rule-based supervisory control strategy. The forward-facing dynamic simulation model at the centre of the framework is built in Hopsan, a multi-disciplinary open-source tool developed at Linköping University. The optimization is set up and conducted for an example application of an on-road light-duty truck over standard drive cycles. Both results from these experiments as well as the framework itself are studied and evaluated. Relevant design aspects, such as explicit design relations to be considered and performance requirements for more robust design, are identified and addressed, and the optimization problem is analysed with regard to algorithm performance and problem formulation. The final result is an optimization framework that can be adjusted for further in-depth studies, for example through the inclusion of additional components or optimization objectives, and extendable for comparative analysis of different topologies, applications and problem formulations.  

    List of papers
    1. System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle
    Open this publication in new window or tab >>System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle
    2014 (English)In: PROCEEDINGS OF THE 8TH FPNI PH.D SYMPOSIUM ON FLUID POWER, 2014, ASME Press, 2014, p. V001T03A004-Conference paper, Published paper (Refereed)
    Abstract [en]

    Amongst the hybrid vehicle propulsion solutions aiming to improve fuel efficiency, hybrid electric solutions currently receive most attention, especially on the market. However, hydraulic hybrids are an interesting alternative, especially for heavier vehicles due to higher power density which is beneficial if higher masses are moved. As a step towards a comprehensive design framework to compare several possible hydraulic hybrid architectures for a specified application and usage profile, the model of a series hydraulic hybrid vehicle was previously introduced and initially studied concerning component sizing for an exemplary light-duty vehicle in urban traffic. The vehicle is modeled in the Hopsan simulation tool. A comparably straight-forward engine management is used for the vehicle control; both pump and engine controls are based on the hydraulic accumulator’s state-of-charge. The model is developed further with respect to the accumulator component model. Based on that, the influence of several system and component parameters, such as maximum system pressure and engine characteristics, as well as controller parameters on the vehicle’s performance is analyzed. The goal is to allow for more understanding of the system’s characteristics to facilitate future optimization of the system.

    Place, publisher, year, edition, pages
    ASME Press, 2014
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-114212 (URN)10.1115/FPNI2014-7840 (DOI)000359389400029 ()978-0-7918-4582-0 (ISBN)
    Conference
    8th FPNI Ph.D Symposium on Fluid Power, Lappeenranta, Finland, June 11–13, 2014
    Available from: 2015-02-13 Created: 2015-02-13 Last updated: 2018-03-09
    2. Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle
    Open this publication in new window or tab >>Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle
    2015 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.

    Series
    Scandinavian International Conference on Fluid Power (SICFP), ISSN 2342-2726
    National Category
    Vehicle Engineering
    Identifiers
    urn:nbn:se:liu:diva-122004 (URN)
    Conference
    14th Scandinavian International Conference on Fluid Power (SICFP'15), Tampere, Finland
    Available from: 2015-10-14 Created: 2015-10-14 Last updated: 2018-03-09
    3. Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design
    Open this publication in new window or tab >>Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design
    2016 (English)In: Proceedings of the 9th FPNI Ph.D. Symposium on Fluid Power (FPNI2016), American Society of Mechanical Engineers , 2016, article id V001T01A041Conference paper, Published paper (Refereed)
    Abstract [en]

    Hybridization of a vehicle’s drivetrain can in principle help to improve its energy efficiency by allowing for recuperation of kinetic energy and modulating the engine’s load. How well this can be realized depends on appropriate sizing and control of the additional components. The system is typically designed sequentially, with the hardware setup preceding the development and tuning of advanced controller architectures. Taking an alternative approach, component sizing and controller tuning can be addressed simultaneously through simulation-based optimization.

    The results of such optimizations, especially with standard algorithms with continuous design variable ranges, can however be difficult to realize, considering for example limitations in available components. Furthermore, drive-cycle based optimizations are prone to cycle-beating. This paper examines the results of such simulation-based optimization for a series hydraulic hybrid vehicle in terms of sensitivity to variations in design parameters, system parameters and drive cycle variations. Additional relevant aspects concerning the definition of the optimization problem are pointed out.

    Place, publisher, year, edition, pages
    American Society of Mechanical Engineers, 2016
    Keywords
    Weight (Mass), Automotive design, Cycles, Optimization, Control equipment, Simulation, Design, Hybrid electric vehicles, Hardware, Stress
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-135737 (URN)10.1115/FPNI2016-1567 (DOI)978-0-7918-5047-3 (ISBN)
    Conference
    9th FPNI Ph.D. Symposium on Fluid Power, Florianópolis, SC, Brazil, October 26–28, 2016
    Available from: 2017-03-17 Created: 2017-03-17 Last updated: 2018-03-09
    4. Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle
    Open this publication in new window or tab >>Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle
    2019 (English)In: International Journal of Fluid Power, ISSN 1439-9776, Vol. 20, no 1, p. 27-51Article in journal (Refereed) Published
    Abstract [en]

    Hybridisation of hydraulic drivetrains offers the potential of efficiency improvement for on – and off-road applications. To realise the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process. Addressing component selection and control parameterisation simultaneously through simulation-based optimisation allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimisation framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance. A number of optimisation experiments for an on-road light-duty vehicle, focused on standard-drive-cycle-performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2019
    Keywords
    Simulation-based optimization, hydraulic hybrid vehicle, series hybrid, simultaneous design and control optimization, Hopsan
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-152353 (URN)10.1080/14399776.2018.1527122 (DOI)000514452100002 ()2-s2.0-85055674140 (Scopus ID)
    Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2021-01-15Bibliographically approved
    5. Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
    Open this publication in new window or tab >>Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
    2020 (English)In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 52, no 3, p. 446-464Article in journal (Refereed) Published
    Abstract [en]

    Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2020
    Keywords
    Simulation-based optimization, information entropy-rate-based performance index, robustness analysis, direct search optimization, hydraulic hybrid vehicle
    National Category
    Vehicle Engineering
    Identifiers
    urn:nbn:se:liu:diva-156185 (URN)10.1080/0305215X.2019.1590566 (DOI)000510053200005 ()
    Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2020-02-17Bibliographically approved
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    Simulation-Based Optimization of a Series Hydraulic Hybrid Vehicle
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  • 10.
    Bhargav, Nikhil
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Institute of System Architectures in Aeronautics, German Aerospace Center.
    Elangovan, Vasanth
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Institute of System Architectures in Aeronautics, German Aerospace Center.
    Knowledge-Based Engineering Application For Fuselage Integration And Cabin Design2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The pace of development in aviation technology is increasing, and there is a constantneed for new concepts to keep up. An innovative concept is desired to reach the netzero emission and sustainability target visualized in Flight path 2050. Introducing digital models and virtualization into aviation fields reduces time consumption onmanual modelling and increases design accuracy. Digital mock-up models also helpin minimizing costs due to errors in the later stage of development or manufacturing. The Institute of Systems Architecture in Aeronautics at German AerospaceCenter (DLR) works in digitizing cabin design environments with extensive implementation of the Knowledge-Based Engineering (KBE) approach. The virtual cabindesign system tool also known as Fuselage Geometry Assembler (FUGA) providesa digital model of the cabin of both single and twin aisle configurations of commercial aircraft. The information of aircraft characteristics is provided to FUGA using Common Parametric Aircraft Configuration Schema (CPACS). CPACS coupled with FUGA provides the user with a consistent model of aircraft and cabindesign, when viewed through a virtual platform provides an immersive experienceto be inside an aircraft cabin before physical production. The multidisciplinary capability of FUGA provides experts from different disciplines to perform analysis such as vibration analysis on the cabin environment. For ease of usage and better visualization of information from FUGA, a web-based application through Flask is hosted for FUGA. This enables the user to access the FUGA tool without the needof installing the tool on their devices. With the world now moving towards a greener approach, an alternative propulsion system may require a different fuel tank configuration. Retro-fit of liquid hydrogen fuel tank into an existing aircraft’s fuselage is done using FUGA tool and aircraft performance analysis is conducted and the outcomes are studied. The enhanced and advanced model of twin-aisle configuration, now on par with single-aisle configuration is used for hydrogen tank sensitivity analysis. The comparative study of different aisle configurations retro-fitted with liquidhydrogen fuel tank is further conducted for arriving at an optimal design point fora balance in range and passenger capacity.

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    fulltext
  • 11. Order onlineBuy this publication >>
    Björnsson, Andreas
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.
    Automated layup and forming of prepreg laminates2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Composite materials like carbon fiber-reinforced polymers (CFRPs) present highly appealing material properties, as they can combine high strength with low weight. In aerospace applications, these properties help to realize lightweight designs that can reduce fuel consumption. Within the aerospace industry, the use of these types of materials has increased drastically with the introduction of a new generation of commercial aircraft. This increased use of CFRP drives a need to develop more rational manufacturing methods.

    For aerospace applications, CFRP products are commonly manufactured from a material called prepreg, which consists of carbon fibers impregnated with uncured polymer resin. There are two dominant manufacturing technologies for automated manufacturing using prepreg, automated tape layup and automated fiber placement. These two technologies are not suitable for all types of products, either due to technical limitations or a combination of high investment costs and low productivity. Automation alternatives to the two dominant technologies have been attempted, but have so far had limited impact. Due to the lack of automation alternatives, manual manufacturing methods are commonly employed for the manufacturing of complex-shaped products in low to medium manufacturing volumes.

    The research presented in this thesis aims to explore how automated manufacturing systems for the manufacturing of complex CFRP products made from prepreg can be designed so that they meet the needs and requirements of the aerospace industry, and are suitable for low to medium production volumes. In order to explore the area, a demonstrator-centered research approach has been employed. A number of demonstrators, in the form of automated manufacturing cells, have been designed and tested with industrial and research partners. The demonstrators have been used to identify key methods and technologies that enable this type of manufacturing, and to analyze some of these methods and technologies in detail. The demonstrators have also been used to map challenges that affect the development of enabling methods and technologies.

    Automated manufacturing of products with complex shapes can be simplified by dividing the process into two steps. Thin layers of prepreg are laid up on top of each other to form flat laminates that are formed to the desired shape in subsequent forming operations. The key methods and technologies required to automate such a system are methods and technologies for automated prepreg layup, the automated removal of backing paper and the forming of complex shapes. The main challenges are the low structural rigidity and tacky nature of prepreg materials, the extensive quality requirements in the aerospace industry and the need for the systems to handle a wide array of prepreg shapes.

    The demonstrators show that it is possible to automate the manufacturing of complexshaped products using automated layup and forming of prepreg laminates. Tests using the demonstrators indicate that it is possible to meet the quality requirements that apply to manual manufacturing of similar products.

    List of papers
    1. Composite Manufacturing: How Improvement Work Might Lead to Renewed Product Validation
    Open this publication in new window or tab >>Composite Manufacturing: How Improvement Work Might Lead to Renewed Product Validation
    2012 (English)In: Proceedings of the 5th International Swedish Production Symposium / [ed] Mats Björkman, 2012, p. 505-513Conference paper, Published paper (Refereed)
    Abstract [en]

    High-performance polymer composites are mainly used in applications where the benefits of high strength and low weight justify the high material and manufacturing costs. Many of these applications are found today in the aerospace, space and defense industries. Most of today’s commonly used manufacturing methods within this area are highly labor intensive. Furthermore, the quality requirements from the customers require a high level of process control. The purpose of this paper is to explore how changes that are introduced in order to improve productivity in a manufacturing system are managed, particularly with regard to who takes the decision to implement a change and how a change is validated. The study is based on qualitative interviews performed at several companies that manufacture composite components for the aerospace, space and defense sectors. The findings show that the responsibility for deciding to implement a change and the need for validating it are based on many diverse and interconnected factors. Therefore, it is difficult to construct guidelines for early assessment of the scope and cost of a proposed change. Hence each individual change request must be evaluated on its own. The study also shows that the validation process can be adapted to a level that is based on the type of change. In addition, it highlights that control over process parameters in manufacturing is essential.

    Keywords
    composite manufacturing, validation, change request management
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-85268 (URN)978-91-7519-752-4 (ISBN)
    Conference
    5th International Swedish Production Symposium (SPS 2012), 6-8 November 2012, Linköping, Sweden
    Available from: 2012-11-14 Created: 2012-11-14 Last updated: 2017-05-17
    2. Automated Removal of Prepreg Backing Paper - A Sticky Problem
    Open this publication in new window or tab >>Automated Removal of Prepreg Backing Paper - A Sticky Problem
    2013 (English)In: Proceedings of the SAE 2013, Aerotech Congress and Exhibition, 24th-26th September 2013, Montreal,Canada, 2013Conference paper, Published paper (Refereed)
    Abstract [en]

    Automated solutions for manufacturing composite products based on prepreg often imply Automatic Fiber Placement or Automatic Tape Laying. These systems are generally associated with huge investments. For certain manufacturing applications it is interesting to investigate alternatives to find simpler and less costly automation. One example of an automated system could be the use of a standard industrial robot to pick single prepreg plies from an automated cutting machine and stack them to form a plane laminate. This paper is based on a case illustrating a product from the aircraft manufacturing industry. The case will demonstrate a pick and place concept on a general level and illustrate challenges that must be solved. The challenge selected to be the main focus for this paper is an automated process for backing paper removal. A literature review of different gripping technologies reveals several interesting technologies, and the most promising are tested for backing paper removal. The tests show that an automated removal process can be designed by using standard vacuum grippers in combination with mechanical clamping grippers. In order to lift the backing paper with a vacuum gripper an initial separation between the backing paper and prepreg is needed. This separation is most easily mechanically induced by bending the material. The proposed solution for automatic backing paper removal can be integrated in a manufacturing cell for manufacturing of the studied product.

    Keywords
    composite manufacturing, automation, prepreg, gripping technology
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-99344 (URN)10.4271/2013-01-2289 (DOI)
    Conference
    SAE 2013 Aerotech Congress and Exhibition, September 24-26, 2013, Montréal, Quebec, Canada
    Note

    SAE Technical Paper 2013-01-2289

    Available from: 2013-10-16 Created: 2013-10-16 Last updated: 2017-05-17Bibliographically approved
    3. Automation of Composite Manufacturing Using Off-the-shelf Solutions, Three Cases from the Aerospace Industry
    Open this publication in new window or tab >>Automation of Composite Manufacturing Using Off-the-shelf Solutions, Three Cases from the Aerospace Industry
    2015 (English)In: Proceedings of the 20th International Conference on Composite Materials, 2015Conference paper, Published paper (Other academic)
    Abstract [en]

    With an increased use of composite materials follows a need for rational, cost-efficient manufacturing processes. This paper explores how off-the-shelf solutions, developed for other purposes than composite manufacturing, can be used to build systems for automated composite manufacturing. Three demonstrators, each of them dealing with a specific type of material and all of them representing different manufacturing technologies for automated composite manufacturing, are presented and analyzed to find aspects that affect the ability to use off-the-shelf solutions. The three demonstrators target low to medium manufacturing volumes of complex products and they have been developed in collaboration with industrial partners within the aerospace industry. The conclusions drawn from the development of the demonstrators are that it is technically feasible to use off-the-shelf solutions in the three cases while adhering to the high quality standards of the industry. Furthermore three groups of aspects, quality aspects, product aspects and system aspects, which affect the ability to use off-the-shelf solutions for automated composite manufacturing, are identified.

    Keywords
    composite manufacturing, automation, off-the-shelf, aerospace
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-120300 (URN)
    Conference
    ICCM20 - The 20th International Conference on Composite Materials, 19-24th July 2015, Copenhagen Denmark
    Available from: 2015-07-27 Created: 2015-07-27 Last updated: 2023-02-02
    4. Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry
    Open this publication in new window or tab >>Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry
    2016 (English)In: SAE International Journal of Materials & Manufacturing, ISSN 1946-3979, E-ISSN 1946-3987, Vol. 9, no 1, p. 68-74Article in journal (Refereed) Published
    Abstract [en]

    With an increased use of composite materials within the aerospace industry follows a need for rational and cost-effective methods forcomposite manufacturing. Manual operations are still common for low to medium manufacturing volumes and complex products.Manual operations can for example be found in material handling, when picking prepreg plies from a cutter table and stacking them toform a plane laminate in preparation for a subsequent forming operation. Stacking operations of this kind often involves a greatnumber of different ply geometries and removal of backing paper and other protecting materials like plastic. In this paper two differentdemonstrator cells for automated picking of prepreg plies and stacking of plane laminates are presented. One demonstrator is utilizinga standard industrial robot and an advanced end-effector to handle the ply variants. The other demonstrator is using a dual arm robotwhich allow for simpler end-effector design. In combination with a previously developed system for automated removal of backingpapers both systems have shown to be capable of automatically picking prepreg plies from a plane surface and stack them to generate aflat multistack laminate. The dual arm approach has shown advantageous since it result in simpler end-effector design and a successivelay down sequence that result in good adhesion between the plies in the laminate.

    Place, publisher, year, edition, pages
    Warrendale, USA: SAE International, 2016
    Keywords
    Composite, Manufacturing, Automation, Low-cost, Prepreg
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-121602 (URN)10.4271/2015-01-2606 (DOI)000386445700008 ()
    Available from: 2015-09-28 Created: 2015-09-28 Last updated: 2023-02-02Bibliographically approved
    5. Robot-Forming of Prepreg Stacks ‐ Development of Equipment and Methods
    Open this publication in new window or tab >>Robot-Forming of Prepreg Stacks ‐ Development of Equipment and Methods
    Show others...
    2016 (English)In: Proceedings of the 17th European Conference on Composite Materials (ECCM17), 2016Conference paper, Published paper (Other academic)
    Abstract [en]

    Within the aerospace industry the manufacturing of composite components with complex shapes, such as spars, ribs and beams are often manufactured using manual layup and forming of prepreg material. Automated processes for prepreg layup and efficient forming techniques like vacuum forming are sometimes difficult to employ to these type of products due to technical limitations. This paper describes the development of tools and the forming sequence needed to automate sequential forming of a complex shape using an industrial robot. Plane prepreg stacks are formed to the final shape using a dual-arm industrial robot equipped with rolling tools. Tests show that the developed tools and the employed sequence can be used to form stacks to the desired shape with acceptable quality.

    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-129925 (URN)
    Conference
    ECCM17 - 17th European Conference on Composite Materials 26-30th June 2016, Munich, Germany
    Available from: 2016-07-01 Created: 2016-07-01 Last updated: 2023-02-02Bibliographically approved
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  • 12.
    Blixt, Wilma
    et al.
    Linköping University, Department of Management and Engineering, Product Realisation.
    Schönning, Hilda
    Linköping University, Department of Management and Engineering, Product Realisation.
    Design Automation of Air Intake Lips on an Aircraft: How to implement design automation for air intake lips in a later design concept phase2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Air intakes are complex components that are critical for the propulsion of the aircraft. The design has to consider requirements from several different departments, often contradictory. Additionally, the air intakes need to cooperate with other critical components. This makes testing of the models crucial, hence time-demanding. Design automation is a growing field which aims at minimizing repetitive work during product concept development. To follow the increasing digitalization, further investigations of design automation applied on air intakes are significant. 

    The application Imagine and Shape in 3D Experience CATIA handles subdivided surfaces. These surfaces are both flexible and provide a high order of continuity, which is often desired. While design automation in CATIA is well investigated, design automation in Imagine and Shape is not. 

    Knowledge based engineering techniques are often used to implement design automation. The methodology MOKA is frequently used when developing knowledge based engineering applications. This master thesis has followed MOKA in combination with Scrum. 

    The master thesis has resulted in a method to allow automation in Imagine and Shape by linking mesh nodes on subdivided surfaces to reference points that are parameterized. Further, a method for generating air intake configurations as well as the integration with a fuselage has been developed. The method includes wireframe models in Generative Shape Design, subdivided surfaces in Imagine and Shape, scripts in EKL as well as UserForm and scripts in VBA. Additionally, the order of continuity for an integration between air intakes and fuselage has been analyzed using tools in 3D Experience CATIA. 

    A conclusion drawn is that the method for generating air intakes cannot be completely automated. Instantiation and dimension of components can be automated, but manual work is required when using tools in Imagine and Shape during the integration between the components and the fuselage.Two methods for linking mesh nodes to reference points have been identified, one manual and one semi-automatic. The automatic method saves time and mouse clicks by utilizing VBA scripts. Further, the achieved order of continuity of an integration between subdivided surfaces depends on the individual components.

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  • 13.
    Bradley, Andreas
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Gårdhagen, Roland
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Bird-Like Wing Conguration for Pitch Control of a Tailless Aircraft2012Conference paper (Other academic)
    Abstract [en]

    A numerical study of a small bird-like aircraft has been performed. The aim of the study was to investigate how a swing wing (actualized through a constant span morphing wing) can be used for pitch control of a tailless aircraft. The results show that a swing wing can be successfully used, and that the aircraft can be maintained in a trimmed state by only small adjustments of part of the wing. A comparison was also made with a Vortex lattice method, but these results significantly deviated from those obtained with CFD. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.

  • 14.
    Colombi, Raffaele
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    CFD Investigation of Aerodynamic Drag Reduction for an Unloaded Timber Truck2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The road transport industry is facing a strong need for fuel consumption reduction, driven by the necessity of decreasing polluting emissions, such as CO2 and NOX, as well as coping with strict regulations and increasing fuel costs. For road vehicles the aerodynamic drag constitutes a major source of energy consumption, and for this reason improving the aerodynamic performance of the vehicle is an established approach for reducing fuel consumption and greenhouse gases emissions.

    In this Thesis work, Computational Fluid Dynamics (CFD) investigations have been carried out in order to investigate and improve the aerodynamic performance of an unloaded timber truck. The work has been divided in two parts. In a first phase, a preliminary study was carried out on a simplified tractor-trailer model in order to establish a suitable computational grid and turbulence model. The hexcore-mesh showed a better performance over the tet- and poly-mesh types. Among the selected RANS turbulence models, the Realizable kε with Enhanced Wall Treatment (EWT) and y+ > 30 showed the highest reliability of results in

    comparison with experimental data and existing CFD investigations.

    In a second phase, the flow field around the baseline unloaded timber truck was analysed in order to highlight potential regions for drag reduction. The truck cabin-bulkhead gap, bunks, the exposed wheels and the stakes were found make key contribution to the drag build-up. The analysis confirmed the 5-yaw case to be the most representative for the wind-averaged drag coefficient.

    Geometry modifications were implemented in order to improve the aerodynamic performance in the selected areas, and subsequently combined into aero-kits in order to enhance the performance, analysed for the 5-yaw case. The combination of extended side skirts, bulkhead shield and collapsed stakes yielded a remarkable result of more than 30% decrease in the wind-averaged drag coefficient, achieved by reducing the flow separation on the cabin leeward A-pillar, and by shielding areas of high stagnation pressure from the side wind.

    Furthermore, a parallel study was conducted on the development of a procedure for the automatic post-processing of results. The outcome was a set of Python scripts to be used with Kitaware Paraview in order to automatically obtain figures of surface variables distributions, iso-surfaces, velocity profiles, drag build-up and total pressure contours. The procedure was finally extended to include the case comparison.

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  • 15.
    Dahlberg, Joen
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Sedov, Leonid
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Capacity-Driven Automatic Design of Dynamic Aircraft Arrival Routes2018In: 2018 IEEE/AIAA 37TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC), IEEE , 2018, p. 1194-1202Conference paper (Refereed)
    Abstract [en]

    We present a Mixed-Integer Programming framework for the design of aircraft arrival routes in a Terminal Maneuvering Area (TMA) that guarantee temporal separation of aircraft. The output routes constitute operationally feasible merge trees, and guarantee that the overall traffic pattern in the TMA can be monitored by air traffic controllers; in particular, we ensure that all aircraft on the arrival routes are separated in time and all merge points are spatially separated. We present a proof of concept of our approach, and demonstrate its feasibility by experiments for arrival routes during one hour at Stockholm TMA.

  • 16.
    Dannet, Grégoire
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Integration of cryogenic tanks and fuel cells for future hydrogen-powered aircraft2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Hydrogen is seen as the green fuel of the future for the aeronautical sector allowing to reduce the carbon footprint of commercial aviation. It is well established that the release of carbon emissions triggers global warming. Aviation, like many other industries, must reduce them. This study aims to integrate cryogenic hydrogen storage onboard an existing aircraft and study two different propulsion systems, namely hydrogen combustion and fuel cells.

    A cryogenic tank was modelled and then designed to fit in the fuselage of an A321. Two configurations were studied, one consisting of one tank at the rear and the other with two tanks, one at the front and one at the aft. The result showed a significant variation of the centre of gravity for the rear tank configuration, whether the airplane is empty or with payload.

    Among the two propulsion systems investigated, hydrogen combustion requires less of a technological leap than hydrogen fuel cell aircraft. The limitation would be the range due to the lack of volume onboard the aircraft to store the hydrogen fuel. But this new type of propulsion could lay the groundwork for future fuel cell aircraft. The fuel cells technology still needs to improve its power density to compete with current engines but would o er more efficient aircraft and therefore greater range.

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  • 17.
    Devadurgam, Hemanth
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Rajagopal, Soorya
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Munjulury, Raghu Chaitanya
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Modeling and Sizing of Conventional and Electrical Environmental Control Systems2019Report (Refereed)
    Abstract [en]

    Environmental control system holds vital importance as it is responsible for passenger’s ventilation and comfort. This paper presents modelling and sizing of the parameterized model of environmental control systems. Knowledge based engineering application serves as the base for designing and methodology for the environmental control systems. Flexibility in the model enables user to control the size and positioning of the system and also sub-systems  associated with it. Number of passengers serves as the driving input for the environmental control system. A 3-d model gives the exact representation with respect to volume occupied and dependencies on the number of passengers. It also provides a faster method to alter the system to user needs with respect to number of air supply pipes, number of ducts and pipe length. Knowledge based engineering gives the freedom to visualize various options in the conceptual design process.

  • 18.
    Diaz Puebla, Alejandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Munjulury, Raghu Chaitanya
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Sizing of actuators for flight control systems and flaps integration in RAPID2015Report (Other academic)
    Abstract [en]

    The architecture of the flight control system, essentialfor all flight operations, has significantlychanged throughout the years. The first part ofthe work consists of a preliminary sizing modelof an EHA and an EMA. The second part of thework consists of the development of parametricCAD models of different types of flaps and theirintegration in RAPID. This thesis addresses theactuation system architecture of what it is namedas more electric aircraft with electrically poweredactuators. This consists of the development offlexible parametric models of flight control surfaces,being able to adapt to any wing geometryand their automatic integration in RAPID. Furthermore,it represents a first step in the developmentof an automatic tool that allows the user tochoose any possible wing control surface configuration.

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  • 19.
    Dümig, Patrick
    Linköping University, Department of Management and Engineering, Solid Mechanics.
    Transformation of In-Flight Measured Loads to a Fatigue Test Spectrum2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fatigue is a well-recognized issue in lightweight and high-performance aircraft structures. As fatigue failures have led to serious accidents and caused significant economic impact in the past, design against fatigue is crucial. Fatigue testing of full-scale aircraft as well as components is an important tool for the advance identification of potential fatigue issues in both new and operational aircraft. Furthermore, coupon testing is used extensively to obtain allowables for materials and structural details to be used in the design process.

    To obtain accurate results from fatigue testing, not only the test object but also the used load spectrum must accurately represent reality. If the aircraft is operational, an accurate load spectrum can be obtained by measuring the loads in-flight during a sufficiently long period of normal operation of the aircraft. However, the in-flight measured loads data contains an extraordinarily large number of cycles, resulting in long and uneconomical test durations.

    This thesis aims to propose a method for the selection of an optimal filtering level for fatigue test spectra developed from in-flight measured loads. The thesis also discusses and recommends methods for in-flight measurement of loads, cycle counting as well as damage evaluation using a crack-growth approach. Furthermore, ways to validate the proposed method and its practical application are discussed.

    An example filtering study is conducted using four different specimens chosen to represent typical structural details of aircraft. The study uses real in-flight measured loads of a light aircraft and also discusses temperature compensation of the loads data. The effect of filtering on fatigue damage is evaluated using crack-growth simulations conducted at a range of filtering and stress levels. 

    The results show that a remarkable reduction of testing time is possible and as many as 99 % of all cycles in the studied flight load history can be discarded without significantly reducing fatigue damage. The allowable filtering level is shown to differ between the specimens and the different stages of fatigue crack growth. In addition, the applied stress level is found to have a consistent effect on the allowable filtering level.

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    Transformation of In-Flight Measured Loads to a Fatigue Test Spectrum
  • 20. Order onlineBuy this publication >>
    Eek, Magnus
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
    On Credibility Assessment in Aircraft System Simulation2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aeronautical industry is becoming increasingly reliant on Modeling and Simulation (M&S) for use throughout all system development phases, for system verification, and end-user training. To justify and to utilize the full potential of today’s model-based approach, the development of efficient and industrially applicable methods for credibility assessment of M&S efforts is a key challenge.

    This work addresses methods facilitating credibility assessment of simulation models and simulator applications used in aircraft system development. For models of individual aircraft subsystems, an uncertainty aggregation method is proposed that facilitates early model validation through approximate uncertainty quantification. The central idea is to integrate information obtained during component level validation directly into the component equations, and to utilize this information in model level uncertainty quantification.

    In addition to methods intended for models of individual subsystems, this work also proposes a method and an associated tool for credibility assessment of large-scale simulator applications. As a complement to traditional document-centric approaches, static and dynamic credibility information is here presented to end-users directly during simulation. This implies a support for detecting test plan deficiencies, or that a simulator configuration is not a suitable platform for the execution of a particular test. The credibility assessment tool has been implemented and evaluated in two large-scale system simulators for the Saab Gripen fighter aircraft. The work presented herein also includes an industrially applicable workflow for development, validation, and export of simulation models.

    List of papers
    1. Methodology for Development and Validation of Multipurpose Simulation Models
    Open this publication in new window or tab >>Methodology for Development and Validation of Multipurpose Simulation Models
    2012 (English)In: 50th AIAA Aerospace Sciences Meeting Online Proceedings including the New Horizons Forum and Aerospace Exposition (2012), AIAA , 2012Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes a framework for development and validation of multipurpose simulation models. The presented methodology enables reuse of models in different applications with different purposes. The scope is simulation models representing physical environment, physical aircraft systems or subsystems, avionics equipment, and electronic hardware. The methodology has been developed by a small interdisciplinary team, with experience from Modeling and Simulation (M&S) of vehicle systems as well as development of simulators for verification and training. Special care has been taken to ensure usability of the workflow and method descriptions, mainly by means of 1) a user friendly format, easy to overview and update, 2) keeping the amount of text down, and 3) providing relevant examples, templates, and checklists. A simulation model of the Environmental Control System (ECS) of a military fighter aircraft, the Saab Gripen, is used as an example to guide the reader through the workflow of developing and validating multipurpose simulation models. The methods described in the paper can be used in both military and civil applications, and are not limited to the aircraft industry.

    Place, publisher, year, edition, pages
    AIAA, 2012
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-74716 (URN)10.2514/6.2012-877 (DOI)
    Conference
    50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 9–12 January, 2012, Gaylord Opryland Resort & Convention Center, 9-12 January, Nashville, Tennessee
    Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2016-04-25
    2. Study of Industrially Applied Methods for Verification, Validation & Uncertainty Quantification of Simulator Models
    Open this publication in new window or tab >>Study of Industrially Applied Methods for Verification, Validation & Uncertainty Quantification of Simulator Models
    2015 (English)In: International Journal of Modeling, Simulation, and Scientific Computing, ISSN 1793-9623, E-ISSN 1793-9615, Vol. 6, no 2, article id 1550014Article in journal (Refereed) Published
    Abstract [en]

    To better utilize the potential of system simulation models and simulators, industrially applicable methods for Verification, Validation and Uncertainty Quantification(VV&UQ) are crucial. This paper presents an exploratory case study of VV&UQ techniquesapplied on models integrated in aircraft system simulators at Saab Aeronauticsand in driving simulators at the Swedish National Road and Transport Research Institute(VTI). Results show that a large number of Verification and Validation (V&V)techniques are applied, some of which are promising for further development and use insimulator credibility assessment. Regarding the application of UQ, a large gap betweenacademia and this part of industry has been identified, and simplified methods areneeded. The applicability of the NASA Credibility Assessment Scale (CAS) at the studied organizations is also evaluated and it can be concluded that the CAS is consideredto be a usable tool for achieving a uniform level of V&V for all models included in asimulator, although its implementation at the studied organizations requires tailoringand coordination.

    Place, publisher, year, edition, pages
    World Scientific, 2015
    Keywords
    Simulator credibility; simulation model; verification; validation; uncertainty quantification; V&V; VV&UQ; NASA Credibility Assessment Scale
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-115105 (URN)10.1142/S1793962315500142 (DOI)000365772300005 ()
    Projects
    NFFP6 2013-01211
    Funder
    VINNOVA, NFFP6 2013-01211
    Available from: 2015-03-09 Created: 2015-03-09 Last updated: 2023-06-12
    3. Enabling Uncertainty Quantification of Large Aircraft System Simulation Models
    Open this publication in new window or tab >>Enabling Uncertainty Quantification of Large Aircraft System Simulation Models
    2013 (English)In: 4:th CEAS conference, 2013 / [ed] Tomas Melin, Petter Krus, Emil Vinterhav, Knut Övrebo, Linköping University Electronic Press , 2013Conference paper, Published paper (Refereed)
    Abstract [en]

    A common viewpoint in both academia and industry is that that Verification, Validation and Uncertainty Quantification (VV&UQ) of simulation models are vital activities for a successful deployment of model-based system engineering. In the literature, there is no lack of advice regarding methods for VV&UQ. However, for industrial applications available methods for Uncertainty Quantification (UQ) often seem too detailed or tedious to even try. The consequence is that no UQ is performed, resulting in simulation models not being used to their full potential.

    In this paper, the effort required for UQ of a detailed aircraft vehicle system model is estimated. A number of methodological steps that aim to achieve a more feasible UQ are proposed. The paper is focused on 1‑D dynamic simulation models of physical systems with or without control software, typically described by Ordinary Differential Equations (ODEs) or Differential Algebraic Equations (DAEs). An application example of an aircraft vehicle system model is used for method evaluation.

    Place, publisher, year, edition, pages
    Linköping University Electronic Press, 2013
    Keywords
    Model validation, uncertainty analysis, uncertainty quantification
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-99838 (URN)978-91-7519-519-3 (ISBN)
    Conference
    CEAS 2013 - International Conference of the European Aerospace Societies, 16-19 September 2013, Linköping, Sweden
    Available from: 2013-10-21 Created: 2013-10-21 Last updated: 2016-04-25Bibliographically approved
    4. A Framework for Early and Approximate Uncertainty Quantification of Large System Simulation Models
    Open this publication in new window or tab >>A Framework for Early and Approximate Uncertainty Quantification of Large System Simulation Models
    2015 (English)In: Proceedings of the 56th Conference on Simulation and Modelling (SIMS 56), October, 7-9, 2015, Linköping University, Sweden, Linköping: Linköping University Electronic Press, 2015, p. 91-104Conference paper, Published paper (Refereed)
    Abstract [en]

    Uncertainty Quantification (UQ) is vital to ensure credibility in simulation results and to justify model-based design decisions – especially in early development phases when system level measurement data for traditional model validation purposes are scarce. Central UQ challenges in industrial applications are computational cost and availability of information and resources for uncertainty characterization. In an attempt to meet these challenges, this paper proposes a framework for early and approximate UQ intended for large simulation models of dynamical systems. A Modelica simulation model of an aircraft environmental control system including a liquid cooling circuit is used to evaluate the industrial applicability of the proposed framework.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2015
    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 119
    Keywords
    Uncertainty quantification; aleatory uncertainty; epistemic uncertainty; model validation; aircraft system simulation models; Modelica
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-122480 (URN)10.3384/ecp1511991 (DOI)9789176859001 (ISBN)
    Conference
    The 56th Conference on Simulation and Modelling (SIMS 56) 7-9 October 2015
    Funder
    VINNOVA, NFFP6 2013-01211
    Available from: 2015-11-04 Created: 2015-11-04 Last updated: 2018-01-25Bibliographically approved
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  • 21.
    Eek, Magnus
    et al.
    Saab Aeronautics, Linköping, Sweden.
    Karlén, Johan
    Saab Aeronautics, Linköping, Sweden.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
    A Framework for Early and Approximate Uncertainty Quantification of Large System Simulation Models2015In: Proceedings of the 56th Conference on Simulation and Modelling (SIMS 56), October, 7-9, 2015, Linköping University, Sweden, Linköping: Linköping University Electronic Press, 2015, p. 91-104Conference paper (Refereed)
    Abstract [en]

    Uncertainty Quantification (UQ) is vital to ensure credibility in simulation results and to justify model-based design decisions – especially in early development phases when system level measurement data for traditional model validation purposes are scarce. Central UQ challenges in industrial applications are computational cost and availability of information and resources for uncertainty characterization. In an attempt to meet these challenges, this paper proposes a framework for early and approximate UQ intended for large simulation models of dynamical systems. A Modelica simulation model of an aircraft environmental control system including a liquid cooling circuit is used to evaluate the industrial applicability of the proposed framework.

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    fulltext
  • 22.
    Eklund, Adam
    et al.
    Linköping University, Department of Management and Engineering, Machine Design.
    Karner, Jesper
    Linköping University, Department of Management and Engineering, Machine Design.
    Development of a Framework for Concept Selection and Design Automation: Utilizing hybrid modeling for indirect parametric control of subdivision surfaces2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Saab Aeronautics’ section Overall Design and Survivability develops early aircraft concepts and utilizes Computer Aided Design (CAD) to ensure the feasibility of principal- and critical characteristics. Saab has over the years developed several start models of aircrafts in CAD from pre-defined aircraft configurations, which are to some extent non-generic. When new configurations are to be explored, manual- and repetitive work is required if the new configuration cannot be attained solely through parametric modifications of a start model. The complexity of these CAD models also demands great knowledge of how aircraft components interact with each other to ensure compatibility. The project covered in this thesis was thus carried out to develop a more effective way for Saab to create and explore a larger design space. This by creating a framework that consists of a product configurator coupled with a library of generic CAD models.

    The product configurator that was created is the Saab Tradespace Analyzer & Reconfigurator (STAR), which takes compatibility relationships into consideration to facilitate concept selection. The STAR also provides a dynamic design space calculation to indicate how close the user is to a final concept selection. Two generic CAD models were created, a fuselage model and an air inlet model. A skeleton model was also created in order to reduce model dependencies and to control the main geometry of the aircraft product. In addition to these, an already existing wing model was implemented to form the library of generic CAD models. The framework coupling the STAR with the CAD library utilizes design automation to allow automatic CAD model generation of a concept that has been selected within the STAR.

    It was concluded through extrapolation that the created framework would allow Saab to create and explore a larger design space in a more effective way than what is done today, provided the library of CAD models were to contain the same number of components as today’s start models.

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  • 23.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Forssell, Jonas
    Volvo Car Corp, Sweden.
    A NOVEL AXIAL PISTON PUMP/MOTOR PRINCIPLE WITH FLOATING PISTONS DESIGN AND TESTING2018In: PROCEEDINGS OF THE BATH/ASME SYMPOSIUM ON FLUID POWER AND MOTION CONTROL, 2018, AMER SOC MECHANICAL ENGINEERS , 2018, article id V001T01A067Conference paper (Refereed)
    Abstract [en]

    This paper presents the first prototype of a novel axial piston pump/motor of slipper type. The pistons are floating in the cylinders and hence the name floating piston pump. The novel pump design fills a gap in the traditional pump design. The pump is made to fit the automobile requirements to use fluid power in a more prominent manner. One of the expected benefits of this design is its simplicity and therefore the machine does not require high manufacturing capabilities. The production cost is expected to be low. The machine is designed with high number of pistons, which leads to a pump/motor with low noise level. The displacement angle is small, 8 degrees, which leads to low piston speeds with its benefits. The main challenge in the design is the piston seal configuration. The seals will both, deform (ovality) and move in a circle relative to the pistons. The paper discusses design considerations and proposes a design. The efficiency measurement of the first prototype is in level of a series produced slipper type machine at its sweet spot.

  • 24.
    Eriksson, Amanda
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics.
    Reinberth, Simon
    Linköping University, Department of Management and Engineering, Solid Mechanics.
    Influence of thermal barrier coating and cooling flow on turbine blades: Impact of manufacturing tolerances on life assessments2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 25.
    Eriksson, E.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lysell, J.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Larsson, H.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Cheung, Kwan Yee
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Geometric Flow Control Lateral Flow Immunoassay Devices (GFC-LFIDs): A New Dimension to Enhance Analytical Performance2019In: Research (Washington, D.C.), ISSN 2639-5274, article id 8079561Article in journal (Refereed)
    Abstract [en]

    The nitrocellulose (NC) membrane based lateral flow immunoassay device (LFID) is one of the most important and widely used biosensor platforms for point-of-care (PoC) diagnostics. However, the analytical performance of LFID has limitations and its optimization is restricted to the bioassay chemistry, the membrane porosity, and the choice of biolabel system. These bottom neck technical issues resulted from the fact that the conventional LFID design principle has not evolved for many years, which limited the LFID for advanced biosensor applications. Here we introduce a new dimension for LFID design and optimization based on geometric flow control (GFC) of NC membranes, leading to highly sensitive GFC-LFID. This novel approach enables comprehensive flow control via different membrane geometric features such as the width (w) and the length (l) of a constriction, as well as its input angle (?1) and output angle (?2). The GFC-LFID (w=0.5 mm, l=7 mm, ?1= 60, ?2= 45) attained a 10-fold increase in sensitivity for detection of interleukin-6 (IL-6), compared with conventional LFID, whereas reducing by 10-fold the antibody consumption. The GFC-LFID detects IL-6 over a linear range of 0.1-10?ng/mL with a limit of detection (LoD) of 29?pg/mL, which even outperforms some commercial IL-6 LFIDs. Such significant improvement is attained by pure geometric control of the NC membrane, without additives, that only relaying on a simple high throughput laser ablation procedure suitable for integration on regular large-scale manufacturing of GFC-LFIDs. Our new development on GFC-LFID with the combination of facile scalable fabrication process, tailored flow control, improved analytical performance, and reduced antibodies consumption is likely to have a significant impact on new design concept for the LFID industry.

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  • 26.
    Erä-Esko, Niko
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Development and Use of System Modeler 6DOF Flight Mechanics Model in Aircraft Conceptual Design2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents a tool for conceptual design of a traditional configuration aircraft by using a parametric six degrees of freedom (6DOF) flight mechanics model implemented in the Modelica Language using Wolfram System Modeler. Being first only able to model and simulate the uncontrolled flight of an aircraft with fixed mass and centre of gravity (CG), and requiring detailed aerodynamic parameters as an input, the 6DOF model is improved by developing new features to reduce the number of required inputs while also increasing the data output of the simulations.

    First, the propulsion submodel is added with models for alternative propulsions to the existing model of turbofan engines. The energy and fuel consumption is also modelled for all propulsion types, and thus the aircraft model has no longer fixed mass properties, except for aircraft with electric propulsion. To further evaluate the fuel consumption for pre-defined flight missions with given flight speed, altitude and track angles, autopilots for a few different aircraft types are developed. Additionally, the 6DOF model is improved by establishing algebraic and statistical relationships between the aircraft geometric input parameters, aerodynamic coefficients and moments of inertia such that the values for the two last mentioned can be estimated inside the 6DOF model based on the minimum amount of design variables, geometric input parameters and aerodynamic properties of the 2D airfoils used in the wings.

    Ultimately, the improved 6DOF model is evaluated and analysed in terms of its performance in initial weight estimation on aircraft conceptual design stage as well as in predicting the aerodynamic properties.

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  • 27.
    Escolano Andrés, Inés
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Knowledge-Based Flight Control System Integration in RAPID2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis work presents a parametrized integration of the flight control system within RAPID by means of the automation in CATIA V5, using Knowledge Pattern.

    Nowadays aircraft’s design and development processes are not only time-consuming but also incur high economic cost. In addition, system integration is highly a multi-disciplinary design process which often involves a large number of different discipline teams working at the same time and space. The main objective of this thesis is to investigate how CAD (Computer Aided Design) software can be used in the early design stages to define the flight control system integration. The purpose of this work to improve the functionality of an in house produced aircraft conceptual design tool carried out at the Division of Fluid and Mechatronic Systems, Linköping University.

    The work consists of preliminary integration of the RAPID flight control system and the hydraulics associated to it. By defining several reusable templates, the automatic definition of a flight control system within the RAPID aircraft has been achieved.

    Moreover it is a parametrical model which allows the user to modify a high number of features as desired to enhance the design process. For this, a user interface in Microsoft Excel connected to CATIA has also been attained.

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  • 28. Escolano Andrés, Inés
    et al.
    Chaitanya Munjulury, Raghu
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Knowledge-Based Flight Control System Integration in RAPID2015Report (Other academic)
    Abstract [en]

    Nowadays, aircraft’s design and development processes are not only time-consuming but also incur high economic cost. In addition, system integration is highly a multi-disciplinary design process, which involves a large number of different discipline teams working at the same time and space. The main objective of this work is to investigate in the early design stages to define and integrate flight control system. The purpose is to improve the functionality of an in house produced aircraft conceptual design tool RAPID carried out at the Division of Fluid and Mechatronic Systems, Linköping University.

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    Knowledge-Based Flight Control System Integration in RAPID
  • 29.
    Eskilsson, Sofie
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Hanna
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Khan, Suleman
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Gurtov, Andrei
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    DEMONSTRATING ADS-B AND CPDLC ATTACKS WITH SOFTWARE-DEFINED RADIO2020In: 2020 INTEGRATED COMMUNICATIONS NAVIGATION AND SURVEILLANCE CONFERENCE (ICNS), IEEE , 2020Conference paper (Refereed)
    Abstract [en]

    Several studies have shown insufficient security in air traffic communication. Controller-Pilot Datalink Communications (CPDLC) is used to communicate in text over the VHF data link, and Automatic Dependent Surveillance Broadcast (ADS-B) determines the position of an aircraft. The vulnerability of air data communication was confirmed by successful experiments using Software-Defined Radio, where both CPDLC and ADS-B messages were transmitted in a safe environment. Neither ADS-B messages nor CPDLC messages are encrypted during transmission. The encoding of FANS-1/A messages was demonstrated, and the experiments showed that it is possible to send such messages with relatively inexpensive technology.

  • 30.
    Firat, Mehmet Deniz
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Experimental Investigation on Cooling Performance of Additively Manufactured Channels2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 31.
    Gagiu, Răzvan-Florin-Rainer
    et al.
    Linköping University, Department of Management and Engineering, Machine Design.
    Abin, Kakkattil Paulose
    Linköping University, Department of Management and Engineering, Machine Design.
    Modeling and Simulation of novel Environmental Control System for a combat aircraft2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The present thesis deals with the analysis of Environmental Control System (ECS) as a part of the aircraft conceptual design. The research focuses on developing methods for modelling, simulation and optimization of current and future cooling technologies suitable for aircraft applications. The work started with a pre-study in order to establish the suitability of different cooling technologies for ECS application. Therefore, five technologies namely, Bootstrap (BS), Reverse-Bootstrap (RBS), vapour cycle system (VCS), magnetic cooling (MC) and thermo-electric cooling (EC), were assessed from a theoretical point of view by the method of benchmarking. This resulted into the selection of three most suitable technologies that were further modelled and simulated in Dymola. In order to compare the optimum designs for each technology, the models were optimized using the modeFRONTIER software. The comparison was performed based on the optimum ratio of maximum power of cooling and minimum fuel penalty. The results showed that VCS has the “best” performances compared to BS and RBS. In addition to the active technologies, passive cooling methods such as liquid cooling by means of jet-fuel and poly-alpha-olefin were considered to address high heat transfer rates. In order to apply the cooling technologies in the ECS, concept system architectures were formulated using the functional analysis. This led to the identification of basic functions, components and sub-systems interaction. Based on the comparison carried out previously and the functional analysis, two ECS architectures were developed. Design optimization procedure was applied further in order to assess each concept and also to study the differences between the two concept architectures. The results depict the complex interaction of different key parameters of the architectures and their influence on the outcome. The study culminated with a proposed methodology for formulation of systems architecture using information from the optimization results and a robust functional analysis method. To sum up, the thesis proposes a simulation-based optimization method that allows inclusion of ECS system in aircraft conceptual design phase. The study also proves the complexity of the conceptual design stage for ECS architectures which highly influences the design of the combat aircraft.

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    Master Thesis Aircraft Conceptual Design
  • 32.
    Gangadharan, Venkata Krishnan
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Conceptual Design Tool for Aircraft Electrical System2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The conceptual design stage of an aircraft involves many uncertainties with regard to prediction of weight of systems. The current trend is that electrical systems increasingly replace hydraulic and pneumatic systems in an aircraft. This leads to greater uncertainty in weight, size and power requirement prediction.

    This work is an attempt at developing a sizing tool that will allow users to estimate the power requirements and weight of electrical systems for a given size of an aircraft specified either by passenger capacity or by aircraft operating empty weight or by maximum take-off weight.

    As with all predictive tools, the results of this work are based on currently available data, i.e., the specification of existing aircraft. This collection of specification of existing aircrafts would constitute the data library. The accuracy of the result of this work depends greatly on the variety of aircrafts and the level of detail for which the data is available.

    The tool is made in Microsoft Excel with some codes made in VBA to perform Excel calculations.

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    Conceptual Design Tool for Aircraft Electrical System
  • 33.
    Gavel, Hampus
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    On aircraft fuel system design: concept evaluation and system modeling2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    THE LARGEST AND most important fluid system in an aircraft is the fuel system. Obviously, future aircraft projects involve the design of fuel system to some degree. In this project design methodologies for aircraft fuel systems are studied, with the aim to shortening the system development time.

    This is done by means of illustrative examples of how optimization and the use of matrix methods have been developed and implemented at Saab Aerospace in the conceptual design of ale fuel systems. The methods introduces automation early in the development process and increase understanding of how top requirements on the ale level impact low-level engineering parameters such as pipe diameter, pump size, etc.

    The thesis also discusses a systematic approach when building a large simulation model of a fluid system where the objective is to minimize the development time by applying a strategy that enables parallel development and collaborative engineering, and also by building the model to the correct level of detail. By correct level of detail is meant the level that yields a simulation outcome that meets the stakeholders' expectations. The experienced gained at Saab in building a simulation model, mainly from the Gripen fuel system, but also the accumulated experience from other system models, is condensed and fitted into an overall process.

  • 34.
    Ghosh, Soumen
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Experimental pressure loss analysis in a mini tube for a fully developed turbulent airflow.: Mini channels of lengths 22.5 mm to 150 mm in length with a constant diameter of 1.5 mm2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cooling systems in a gas turbine are especially important as the turbine blades and vanes are exposed to extreme temperatures. The relatively cool air is extracted from the compressors and fed to the turbines to cool the turbine blades. The manufacturing of these blades and channels used to cool is especially complicated using conventional manufacturing techniques. Additive Manufacturing (AM) gives the designer much more freedom to design core components. The AM technique currently explored is the Selective Laser Melting process (SLM). The surface area is exposed to the cooling airflow by using lattice structures which can be manufactured at relative ease using AM. This thesis will provide some insights into using AM parts for the cooling, by analyzing the pressure drop that could be expected from superalloys that are manufactured using AM. The surface roughness is an inherent property of the AM components therefore it would be interesting to analyze a turbulent flow through AM channels (CM247LC and INCONEL 939). The thesis deals with turbulent flows as the airflow used for cooling in the gas turbine is most likely turbulent.  The friction factor (Darcy–Weisbach friction factor) is used to relate the impact of the surface roughness to the pressure drop. The results from the previous experiments are contrasted as the flow in the previous experiments was assumed to be fully developed but in reality, it was not. And the accuracy of the previous results to the actual fully developed flow will shed some light on the feasibility of the flow analysis techniques used in the previous experiments. It is found that the previous experimental results for the CM247LC TPs have good agreement with current experimental results but INCONEL 939 exhibits significant deviation. The possible reasons for the deviations are directly linked to the assumptions made to calculate the minor losses. The Test Pieces (TP) analyzed in this thesis have varying length to diameter (L/D) ratios and the impact of the variation of different L/D ratios is analyzed along with varying pressure ratios. Where the flow resistance increases with an increase in L/D and pressure ratio. The technique to accommodate the compressibility of the airflow is also explored in this thesis. Finally, reasons for the manifestation of anomalies are discussed. The probability of the compressibility effects of the airflow on the anomalies was found to be quite high, and concluding remarks are provided.

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  • 35.
    Giota, Argyro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Roszkowska, Aleksandra
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Implementation of Flight Mechanical Evaluation Criteria in an Aircraft Conceptual Design Tool with focus on Longitudinal Motions2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report focuses on the utilisation of flight mechanics in the context of aircraftconceptual design to assess stability, control, and motion characteristics. The pri-mary objective is to acquire the equations of motion and implement longitudinalstability and control criteria using Pacelab Aircraft Preliminary Design 8.1, a com-mercial software tool. The equations and criteria employed in this study are derivedfrom an extensive review of relevant literature.By incorporating a dedicated Flight Mechanics chapter within the software, it be-comes possible to evaluate aircraft concepts under varying conditions. To ensureaccuracy and validity, DATCOM+ and OpenVSP were employed for testing andverification purposes.The key aspects covered in this report include flight mechanics, its implementationin Pacelab APD 8.1, determination of aerodynamic derivatives, formulation of equa-tions of motion, and their application to the B747 aircraft model. The emphasis liesin assessing longitudinal stability and control, including specific characteristics suchas the phugoid and short period modes.This report provides valuable insights into the integration of flight mechanics withinthe Pacelab APD 8.1 software for aircraft conceptual design. The results contributeto a better understanding of stability and control parameters and their impact onaircraft performance.

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  • 36.
    Gummadi, Bala Murali Krishna
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Sourirajan, Rahul Rajan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Investigating the aerodynamic performance of an UAV2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aerodynamic performance of any airborne vehicle is an important characteristic to be considered during the concept development process. Lift and drag forces are the two most important aspects of aerodynamics that dictates vehicle efficiency. As these forces depend on various conditions, evaluating the performance at the intended flight condition is necessary. As the experimental investigations are extremely expensive, computational methods are used to find the performance characteristics of a vehicle in the early design stages. The main focus of this thesis is to find the aerodynamic parameters of an UAV, lift coefficient (Cl) and drag coefficient (Cd) at a predefined flight state and further investigate the trim performance in turn flight state. Two types of computational methods were used namely Panel Methods i.e., Vortex Lattice Method (VLM) and Computational Fluid Dynamics (CFD). These methods differ by computational time and accuracy. Investigations were performed to two UAV models namely UAV1 andUAV2 where both models have minor differences in design. Both VLM and CFDwere used to investigate the performance of UAV1. This was done to find the maximum capability of VLM, which is computationally cheaper. A trim analysis was also performed to find additional parameters to aid the comparison of VLM and CFD. Apart from investigating UAV1 at the required flight states, investigation was also performed at near stall to find the performance of UAV1 in worse flight condition. A comparison of UAV1 and UAV2 was then made to find the best flight states where an UAV can fly fulfilling the designer requirements. UAV2 was then simulated to find the trim condition of a level flight by deflecting the elevator control surfaces in turn flight state. The results from the analysis showed that VLM provides reasonable results within its limitations. From the CFD results, both the UAV’s have sufficient Cl, but the Cd of UAV1 is approximately twice the Cd of UAV2. The turn analysis of the UAV2 showed that at a higher angle of attack, UAV2 can bank at a large bankangle without losing the level flight condition.

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    Master Thesis
  • 37.
    Gundmi Satish, Sajjan
    Linköping University, Department of Management and Engineering, Solid Mechanics.
    Continuous Time Fatigue Modelling for Non-proportional Loading2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fatigue analysis is a critical stage in the design of any structural component. Typically fatigue is analysed during post-processing, but as the size of the analysed component increases, the amount of data stored for the analysis increases simultaneously. This increases the computational and memory requirements of the system, intensifying the work load on the engineer. A continuum mechanics approach namely ’Continuous time fatigue model’, for fatigue analysis is available in a prior study which reduces the computational requirements by simultaneously computing fatigue along with the stress. This model implements a moving endurance surface in the stress space along with the damage evolution equation to compute high-cycle fatigue. In this thesis the continuous time fatigue model is compared with conventional model (ie.Cycle counting) to study its feasibility. The thesis also aims to investigate the continuous time fatigue model and an evolved version of the model is developed for non-proportional load cases to identify its limitations and benefits.

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    sajgu904_ThesisReport
  • 38.
    Hervatte, Abhay Mahesh
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    CFD Simulation of a Fin-Tube Evaporator under icing2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study involves development of a methodology to simulate a fin-tube evaporator under icing conditions using CFD in Ansys® Academic Fluent 2021R1. It aims to build on previous studies performed on heat pumps. It was performed by Abhay M. Hervatte in collaboration with Bosch Thermoteknik AB, Tranås, SE during the spring term of the year 2021. The thesis is published by Linköping University.

    Initially, experiments were conducted to measure the ice growth on the fins of the evaporator as a function of time. A CAD model of the evaporator was then generated. The evaporator geometry was scaled down and simplified to reduce the simulation time. Due to restrictions in the software, the simulations were split into two parts - one for the flow of the refrigerant through the evaporator pipes and another for flow of air over the fins. The internal flow simulation was a steady state simulation consisting of the phase-change of the refrigerant after absorbing heat from the ambient. through the pipes and a transient simulation for the external flow over the fins. The internal flow consisted of multi-phase simulation of the evaporation of the refrigerant - propane - after absorbing heat through the pipe walls. The external flow involved the multi-phase simulation of ice being deposited from humid air on the surface of the fins. The inner surface of the evaporator pipes was used as a bridge, and surface profiles from the internal simulation would be used to transfer the boundary conditions to the other simulation. Results of the ice-film thickness over the fins were obtained and compared to the experimental value and found to be in reasonable agreement with each other, with scope for improvement in the future.

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  • 39.
    Hozic, Dzenan
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering. RISE Res Inst Sweden, Sweden.
    Thore, Carl-Johan
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Cameron, Christopher
    RISE Res Inst Sweden, Sweden.
    Sahbi Loukil, Mohamed
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. RISE Res Inst Sweden, Sweden.
    A new method for simultaneous material and topology optimization of composite laminate structures using Hyperbolic Function Parametrization2021In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 276, article id 114374Article in journal (Refereed)
    Abstract [en]

    This paper presents a new discrete parametrization method for simultaneous topology and material optimization of composite laminate structures, referred to as Hyperbolic Function Parametrization (HFP). The novelty of HFP is the way the candidate materials are parametrized in the optimization problem. In HFP, a filtering technique based on hyperbolic functions is used, such that only one design variable is used for any given number of material candidates. Compared to state-of-the-art methods such Discrete Material and Topology Optimization (DMTO) and Shape Function with Penalization (SFP), HFP has much fewer optimization variables and constraints but introduces additional non-linearity in the optimization problems. A comparative analysis of HFP, DMTO and SFP are performed based on the problem of maximizing the stiffness of composite plates under a total volume constraint and multiple manufacturing constraints using various loads, boundary conditions and input parameters. The comparison shows that all three methods are highly sensitive to the choice of input parameters for the optimization problem, although the performance of HFP is overall more consistent. HFP method performs similarly to DMTO and SFP in terms of the designs obtained and computational cost. However, HFP obtains similar or better objective function values compared to the DMTO and SFP methods.

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  • 40.
    Hozić, Dženan
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering. RISE Research Institutes of Sweden, Division of Materials and Production, Polymers, Fibers and Composites Department, Box 857, Borås, 501 15, Sweden.
    Thore, Carl-Johan
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Division of Materials and Production, Polymers, Fibers and Composites Department, Box 857, Borås, 501 15, Sweden.
    Loukil, Mohamed Sahbi
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Deterministic-based robust design optimization of composite structures under material uncertainty2023In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 322, article id 117336Article in journal (Refereed)
    Abstract [en]

    We propose a new deterministic robust design optimization method for composite laminate structures under worst-case material uncertainty. The method is based on a simultaneous parametrization of topology and material and combines a design problem and a material uncertainty problem into a single min–max optimization problem which provides an efficient approach to handle variation of material properties in stiffness driven design optimization problems. An analysis is performed using a design problem based on a failure criterion formulation to evaluate the ability of the proposed method to generate robust composite designs. The design problem is solved using various loads, boundary conditions and manufacturing constraints. The designs generated with the proposed method have improved objective responses compared to the worst-case response of designs generated with nominal material properties and are less sensitive to the variation of material properties. The analysis indicates that the proposed method can be efficiently applied in a robust structural optimization framework. © 2023 The Author(s)

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  • 41.
    Hällqvist, Robert
    et al.
    Systems Simulation and Concept Design, Saab Aeronautics, Linköping, Sweden.
    Braun, Robert
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Early Insights on FMI-based Co-Simulation of Aircraft Vehicle Systems2017In: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden / [ed] Petter Krus, Liselott Eriksson and Magnus Sethson, Linköping: Linköping University Electronic Press, 2017, Vol. 144, p. 262-270Conference paper (Other academic)
    Abstract [en]

    Modelling and Simulation is extensively used for aircraft vehicle system development at Saab Aeronautics in Linköping, Sweden. There is an increased desire to simulate interacting sub-systems together in order to reveal, and get an understanding of, the present cross-coupling effects early on in the development cycle of aircraft vehicle systems. The co-simulation methods implemented at Saab require a significant amount of manual effort, resulting in scarcely updated simulation models, and challenges associated with simulation model scalability, etc. The Functional Mock-up Interface (FMI) standard is identified as a possible enabler for efficient and standardized export and co-simulation of simulation models developed in a wide variety of tools. However, the ability to export industrially relevant models in a standardized way is merely the first step in simulating the targeted coupled sub-systems. Selecting a platform for efficient simulation of the system under investigation is the next step. Here, a strategy for adapting coupled Modelica models of aircraft vehicle systems to TLM-based simulation is presented. An industry-grade application example is developed, implementing this strategy, to be used for preliminary investigation and evaluation of a cosimulation framework supporting the Transmission Line element Method (TLM). This application example comprises a prototype of a small-scale aircraft vehicle systems simulator. Examples of aircraft vehicle systems are environmental control systems, fuel systems, and hydraulic systems. The tightly coupled models included in the application example are developed in Dymola, OpenModelica, and Matlab/Simulink. The application example is implemented in the commercial modelling tool Dymola to provide a reference for a TLM-based master simulation tool, supporting both FMI and TLM. The TLM-based master simulation tool TLMSimulator is investigated in terms of model import according to the FMI standard with respect to a specified set of industrial needs and requirements.

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  • 42.
    Hällqvist, Robert
    et al.
    Saab Aeronautics, Linköping, Sweden.
    Eek, Magnus
    Saab Aeronautics, Linköping, Sweden.
    Braun, Robert
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    METHODS FOR AUTOMATING MODEL VALIDATION: STEADY-STATE IDENTIFICATION APPLIED ON GRIPEN FIGHTER ENVIRONMENTAL CONTROL SYSTEM MEASUREMENTS2016In: Proceedings of the 30th congress of the International Council  of the Aeronautical Sciences, International Council of the Aeronautical Sciences , 2016Conference paper (Refereed)
    Abstract [en]

    Model Validation and Verification (V&V) has historically often been considered a final step in the model development process. However, to justify model-based design decisions throughout the entire system development process, a methodology for continuous model V&V is essential. That is, model V&V activities should be fast and easy to reiterate as new information becomes available. Using a high fidelity simulation model of the Environmental Control System (ECS) in the Saab Gripen fighter aircraft as a guiding example, this paper further extends to an existing semiautomatic framework for model steady-state validation developed during ECS model validation efforts. Generic methods for identification of steady-state operation are a prerequisite for steady-state validation of industry grade physics based models against insitu measurements. Four different established methods for steady-state identification are investigated and compared: steady-state conditions on the standard deviation estimated from in-situ measurements, conditions on the variation coefficient, t-test on the slope of a simple regression line, and comparison of differently estimated variances. The methods’ applicability, on ECS measurements in particular, is evaluated utilizing steady-state identification needs defined during Gripen ECS model validation activities.

    Model Validation and Verification (V&V) has historically often been considered a final step in the model development process. However, to justify model-based design decisions throughout the entire system development process, a methodology for continuous model V&V is essential. That is, model V&V activities should be fast and easy to reiterate as new information becomes available.

    Using a high fidelity simulation model of the Environmental Control System (ECS) in the Saab Gripen fighter aircraft as a guiding example, this paper further extends to an existing semi-automatic framework for model steady-state validation developed during ECS model validation efforts. Generic methods for identification of steady-state operation are a prerequisite for steady-state validation of industry grade physics based models against in-situ measurements. Four different established methods for steady-state identification are investigated and compared: steady-state conditions on the standard deviation estimated from in-situ measurements, conditions on the variation coefficient, t-test on the slope of a simple regression line, and comparison of differently estimated variances. The methods’ applicability, on ECS measurements in particular, is evaluated utilizing steady-state identification needs defined during Gripen ECS model validation activities.

  • 43.
    Hällqvist, Robert
    et al.
    Saab Aeronautics, Linköping, Sweden.
    Eek, Magnus
    Saab Aeronautics, Linköping, Sweden.
    Lind, Ingela
    Saab Aeronautics, Linköping, Sweden.
    Gavel, Hampus
    Saab Aeronautics, Linköping, Sweden.
    Validation Techniques Applied on the Saab Gripen FighterEnvironmental Control System Model2015In: Proceedings of the 56th SIMS / [ed] Lena Buffoni, Adrian Pop, and Bernhard Thiele, Linköping, 2015, p. 199-210, article id ecp15119199Conference paper (Refereed)
    Abstract [en]

    The Environmental Control System (ECS) of the Saab Gripen fighter provides a number of vital functions, such as provision of coolant air to the avionics, comfort air to the cockpit, and pressurization of the aircraft fuel system. To support system design, a detailed simulation model has been developed in the Modelica-based tool Dymola. The model needs to be a “good system representation”, during both steady-state operation and relevant dynamic events, if reliable predictions are to be made regarding cooling performance, static loads in terms of pressure and temperature, and various other types of system analyses. A framework for semi-automatic validation of the ECS model against measurements is developed and described in this paper. The framework extends a proposed formal methodology of semi-automaticmodel validation against in-situ measurements to the model development process implemented at Saab.Applied methods for validating the model in steady-state operation and during relevant dynamic events are presented in detail. The developed framework includes automatic filtering of measurement points defined as steady-state operation and visualization techniques applied on validation experiments conducted in the previously mentioned points. The proposed framework both simplify continuous validation throughout the system development process and enables a smooth transition towards a more independent verification and validation process.

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  • 44.
    Jouannet, Christopher
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Lundström, David
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Sobron, Alejandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Annes da Silva, Roberto Gil
    Instituto Tecnológico de Aeronáutica, São José dos Campos, Brazil.
    Catalano, Fernando
    USP, San Carlos, Brazil.
    Greco, Paulo
    USP, San Carlos, Brazil.
    Aerodynamic database of a subscale demonstrator2017In: 35th AIAA Applied Aerodynamics Conference, Reston, VA, USA, 2017, article id 2017-4075Conference paper (Refereed)
    Abstract [en]

    This paper reports the current status of a joint Swedish-Brazilian research project aiming at exploring sub scale flight testing. A 13% scale fighter aircraft is used as a test bench for developing methods and procedures for data acquisition. This paper will present an aerodynamic database as a partial result of the collaborative project.

  • 45.
    Jouannet, Christopher
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Lundström, David
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Melin, Tomas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Berry, Patrick
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Design and Flight Testing of a Solar Powered Aircraft, a Student Challenge2013Conference paper (Other academic)
    Abstract [en]

    The presented work considers designing, building and flight testing a solar poweraircraft as a student project. The goal is to allow student to participate in an aircraft projectfrom design to flight test in order to acquire aircraft design knowledge from theoretical andpractical means. A first theoretical part consists of creating a sizing program for studyingdifferent concepts. Then the gathered knowledge will result in the realization of a flyingdemonstrator. This was realized during a student project over a 5 month period

  • 46. Order onlineBuy this publication >>
    Kapidzic, Zlatan
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Static and Fatigue Failure of Bolted Joints in Hybrid Composite-Aluminium Aircraft Structures2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of fibre composites in the design of load carrying aircraft structures has been increasing over the last few decades. At the same time, aluminium alloys are still present in many structural parts, which has led to an increase of the number of hybrid composite-aluminium structures. Often, these materials are joined at their interface by bolted connections. Due to their different response to thermal, mechanical and environmental impact, the composite and the aluminium alloy parts are subject to different design and certification practices and are therefore considered separately.The current methodologies used in the aircraft industry lack well-developed methods to account for the effects of the mismatch of material properties at the interface.One such effect is the thermally induced load which arises at elevated temperature due to the different thermal expansion properties of the constituent materials. With a growing number of hybrid structures, these matters need to be addressed. 

    The rapid growth of computational power and development of simulation tools in recent years have made it possible to evaluate the material and structural response of hybrid structures without having to entirely rely on complex and expensive testing procedures.However, as the failure process of composite materials is not entirely understood, further research efforts are needed in order to develop reliable material models for the existing simulation tools.

    The work presented in this dissertation involves modelling and testing of bolted joints in hybrid composite-aluminium structures.The main focus is directed towards understanding the failure behaviour of the composite material under static and fatigue loading, and how to include this behaviour in large scale models of a typical bolted airframe structure in an efficient way. In addition to that, the influence of thermally induced loads on the strength and fatigue life is evaluated in order to establish a design strategy that can be used in the industrial context.

    The dissertation is divided into two parts. In the first one, the background and the theory are presented while the second one consists of five scientific papers.

    List of papers
    1. Conceptual studies of a composite-aluminum hybrid wing box demonstrator
    Open this publication in new window or tab >>Conceptual studies of a composite-aluminum hybrid wing box demonstrator
    2014 (English)In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 32, no 1, p. 42-50Article in journal (Refereed) Published
    Abstract [en]

    This paper presents a study of two different hybrid composite-aluminum concepts applied to a winglike structure which is exposed to mechanical  and thermal load. The aim of the study is to determine the most suitable  hybrid concept to later on be used in structural fatigue and static testing. In both concepts, the mass is optimized with respect to two different sets of requirements, one of which is currently in use in the fighter aircraft industry and one which is a modified version of the current requirement set. The issues considered in the study are mass, thermal behavior, buckling, bolted joints, failure criteria and fatigue damage, and they are examined in the frame of both requirement sets. The results clearly indicate the order of criticality between the different criteria in the different parts of each concept. Also, the comparison of two requirement sets gives an idea of the degree of influence of the modified criteria on the hybrid concepts and their mass. Based on the mass and the structural behavior in a thermal-mechanical loading one of the hybrid concepts is chosen for further studies and testing.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Hybrid structure, Wing structure, Composite-aluminum, Thermal load, Conceptual study
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-91892 (URN)10.1016/j.ast.2013.11.002 (DOI)000331921900006 ()
    Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved
    2. Finite element modeling of mechanically fastened composite-aluminum joints in aircraft structures
    Open this publication in new window or tab >>Finite element modeling of mechanically fastened composite-aluminum joints in aircraft structures
    2014 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 109, p. 198-210Article in journal (Refereed) Published
    Abstract [en]

    A three-dimensional, solid finite element model of a composite-aluminum single-lap bolted joint with a countersunk titanium fastener is developed. The model includes progressive damage behavior of the composite and a plasticity model for the metals. The response to static loading is compared to experimental results from the literature. It is shown that the model predicts the initiation and the development of the damage well, up to failure load. The model is used to evaluate the local force-displacement responses of a number of single-lap joints installed in a hybrid composite-aluminum wing-like structure. A structural model is made where the fasteners are represented by two-node connector elements which are assigned the force-displacement characteristics determined by local models. The behavior of the wing box is simulated for bending and twisting loads applied together with an increased temperature and the distribution of fastener forces and the progressive fastener failure is studied. It is shown that the fastener forces caused by the temperature difference are of significant magnitude and should be taken into account in the design of hybrid aircraft structures. It is concluded that, the account of the non-linear response of the joints results in a less conservative load distribution at ultimate failure load.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Bolted joints, Composite-aluminum, Finite element modeling, Hybrid wing structures
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-91893 (URN)10.1016/j.compstruct.2013.10.056 (DOI)000331671700020 ()
    Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved
    3. Quasi-static bearing failure of CFRP composite in biaxially loaded bolted joints
    Open this publication in new window or tab >>Quasi-static bearing failure of CFRP composite in biaxially loaded bolted joints
    2015 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 125, p. 60-71Article in journal (Refereed) Published
    Abstract [en]

    Hybrid composite-aluminium bolted joints develop internal loads at elevated temperatures, due to the difference in thermal expansion properties of their constituent materials. In aircraft joints, the thermally induced bolt loads are commonly directed perpendicular to the mechanical loads, inducing a biaxial bearing load state. In this work, carbon-epoxy laminate specimens were tested in uniaxial and biaxial quasi-static bearing failure experiments in a specially designed test rig, at elevated temperature. A microscopy study of a failed specimen revealed that the failure process was mainly driven by fibre kinking, although extensive matrix cracking and delaminations were also found. The experiments were simulated by three-dimensional, explicit, finite element analyses, which included intralaminar damage and delamination. The experimental and simulated bearing failure loads differed by 1.7% in the uniaxial case and 2.1% in the biaxial case. It was suggested that the load-displacement response is influenced by the interaction of all damage mechanisms. Delamination modelling was, however, not essential for the prediction of the maximal bearing strength. The same effective bearing strengths were obtained for the biaxially loaded specimens as for the uniaxially loaded ones, but the damage accumulation process and the resulting damage distributions were different. (C) 2015 Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Hybrid joint; Carbon-epoxy; Thermally induced load; Bearing failure; Finite element analysis
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-118234 (URN)10.1016/j.compstruct.2015.01.038 (DOI)000353177600008 ()
    Note

    Funding Agencies|Swedish Armed Forces; Swedish Defence Materiel Administration; Swedish Governmental Agency

    Available from: 2015-05-22 Created: 2015-05-22 Last updated: 2017-12-04
    4. Fatigue bearing failure of CFRP composite in biaxially loaded bolted joints at elevated temperature
    Open this publication in new window or tab >>Fatigue bearing failure of CFRP composite in biaxially loaded bolted joints at elevated temperature
    2015 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 127, p. 298-307Article in journal (Refereed) Published
    Abstract [en]

    Hybrid composite-aluminium structures develop internal loads when exposed to elevated temperatures, due to the different thermal expansion properties of the constituent materials. In aircraft structures with long rows of bolted joints, the mechanical and the thermally induced bolt loads are oriented in different directions, creating a biaxial bearing load state. In this study, the bearing fatigue failure process and the influence of the biaxial load state on the failure are investigated. An experimental set-up was designed, where both the mechanical and the thermally induced bolt loads were applied by means of mechanical load actuators. Two-bolt, double-lap joints with quasi-isotropic carbon-epoxy composite specimens were subjected to uniaxial and biaxial cyclic loading at 90 degrees C. A microscopy study of the bearing plane revealed that the main fatigue driving mechanisms were matrix cracking and fibre-matrix debonding. Motivated by these findings, a fatigue prediction model based on the kinetic theory of fracture for polymer matrices was run in a finite element code and the results showed a satisfactory correlation to the experimental results. The biaxial loading resulted in a longer fatigue life than the uniaxial loading, for the same peak resultant force, which was explained by the smaller effective stress range in the biaxial case.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Hybrid bolted joint; Carbon-epoxy; Thermally induced load; Fatigue bearing failure
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:liu:diva-118835 (URN)10.1016/j.compstruct.2015.03.031 (DOI)000354139800028 ()
    Note

    Funding Agencies|Swedish Armed Forces, Swedish Defence Materiel Administration; Swedish Governmental Agency for Innovation Systems

    Available from: 2015-06-08 Created: 2015-06-04 Last updated: 2017-12-04
    5. Fatigue bearing failure of CFRP composite in bolted joints exposed to biaxial variable amplitude loading at elevated temperature
    Open this publication in new window or tab >>Fatigue bearing failure of CFRP composite in bolted joints exposed to biaxial variable amplitude loading at elevated temperature
    2016 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 142, p. 71-77Article in journal (Refereed) Published
    Abstract [en]

    Hybrid structures than contain composite-aluminium interfaces tend to develop internal loads at elevated temperatures. In long bolted joints, the thermally induced bolt loads are superimposed onto the mechanically applied load and can induce a biaxial bearing load state. This paper presents an experimental and numerical study of the bearing fatigue failure of carbon-epoxy laminate specimens, exposed to uniaxial and biaxial variable amplitude loading at 90C. A specifically designed experimental rig was used, where both the mechanical and the thermally induced bolt loads were applied by means of mechanical load actuators. A fatigue model based on the kinetic theory of fracture for polymers, which was previously implemented for constant amplitude loading, is expanded to account for the variable amplitude load history. The results suggest that the biaxial loading gives a longer fatigue life than the uniaxial loading for the same maximum peak resultant force. This result can be utilized as a conservative dimensioning strategy by designing biaxially loaded joints in terms of maximum peak resultant bearing load using uniaxial fatigue data.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keywords
    Carbon-epoxy, Thermally induced load, Fatigue bearing failure, Variable amplitude loading
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:liu:diva-122420 (URN)10.1016/j.compstruct.2016.01.064 (DOI)000372691300008 ()
    Note

    Vid tiden för disputation förelåg publikationen som manuskript

    Funding agencies:  Swedish Armed Forces; Swedish Defence Materiel Administration; Swedish Governmental Agency for Innovation Systems

    Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2017-12-01Bibliographically approved
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  • 47. Order onlineBuy this publication >>
    Kapidzic, Zlatan
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Strength analysis and modeling of hybrid composite-aluminum aircraft structures2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The current trend in aircraft design is to increase the proportion of fiber composites in the structures. Since many primary parts also are constructed using metals, the number of hybrid metal-composite structures is increasing. Such structures have traditionally often been avoided as an option because of the lack of methodology to handle the mismatch between the material properties. Composite and metal properties differ with respect to: thermal expansion, failure mechanisms, plasticity, sensitivity to load type, fatigue accumulation and scatter, impact resistance and residual strength, anisotropy, environmental sensitivity, density etc. Based on these differences, the materials are subject to different design and certification requirements. The issues that arise in certification of hybrid structures are: thermally induced loads, multiplicity of failure modes, damage tolerance, buckling and permanent deformations, material property scatter, significant load states etc. From the design point of view, it is a challenge to construct a weight optimal hybrid structure with the right material in the right place. With a growing number of hybrid structures, these problems need to be addressed. The purpose of the current research is to assess the strength, durability and thermo-mechanical behavior of a hybrid composite-aluminum wing structure by testing and analysis. The work performed in this thesis focuses on the analysis part of the research and is divided into two parts. In the first part, the theoretical framework and the background are outlined.Significant material properties, aircraft certification aspects and the modeling framework are discussed.In the second part, two papers are appended. In the first paper, the interaction of composite and aluminum, and their requirements profiles,is examined in conceptual studies of the wing structure. The influence of the hybrid structure constitution and requirement profiles on the mass, strength, fatigue durability, stability and thermo-mechanical behavior is considered. Based on the conceptual studies, a hybrid concept to be used in the subsequent structural testing is chosen. The second paper focuses on the virtual testing of the wing structure. In particular, the local behavior of hybrid fastener joints is modeled in detail usingthe finite element method, and the result is then incorporated into a global model using line elements. Damage accumulation and failure behavior of the composite material are given special attention. Computations of progressive fastener failure in the experimental setup are performed. The analysis results indicate the critical features of the hybrid wing structure from static, fatigue, damage tolerance and thermo-mechanical points of view.

    List of papers
    1. Conceptual studies of a composite-aluminum hybrid wing box demonstrator
    Open this publication in new window or tab >>Conceptual studies of a composite-aluminum hybrid wing box demonstrator
    2014 (English)In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 32, no 1, p. 42-50Article in journal (Refereed) Published
    Abstract [en]

    This paper presents a study of two different hybrid composite-aluminum concepts applied to a winglike structure which is exposed to mechanical  and thermal load. The aim of the study is to determine the most suitable  hybrid concept to later on be used in structural fatigue and static testing. In both concepts, the mass is optimized with respect to two different sets of requirements, one of which is currently in use in the fighter aircraft industry and one which is a modified version of the current requirement set. The issues considered in the study are mass, thermal behavior, buckling, bolted joints, failure criteria and fatigue damage, and they are examined in the frame of both requirement sets. The results clearly indicate the order of criticality between the different criteria in the different parts of each concept. Also, the comparison of two requirement sets gives an idea of the degree of influence of the modified criteria on the hybrid concepts and their mass. Based on the mass and the structural behavior in a thermal-mechanical loading one of the hybrid concepts is chosen for further studies and testing.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Hybrid structure, Wing structure, Composite-aluminum, Thermal load, Conceptual study
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-91892 (URN)10.1016/j.ast.2013.11.002 (DOI)000331921900006 ()
    Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved
    2. Finite element modeling of mechanically fastened composite-aluminum joints in aircraft structures
    Open this publication in new window or tab >>Finite element modeling of mechanically fastened composite-aluminum joints in aircraft structures
    2014 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 109, p. 198-210Article in journal (Refereed) Published
    Abstract [en]

    A three-dimensional, solid finite element model of a composite-aluminum single-lap bolted joint with a countersunk titanium fastener is developed. The model includes progressive damage behavior of the composite and a plasticity model for the metals. The response to static loading is compared to experimental results from the literature. It is shown that the model predicts the initiation and the development of the damage well, up to failure load. The model is used to evaluate the local force-displacement responses of a number of single-lap joints installed in a hybrid composite-aluminum wing-like structure. A structural model is made where the fasteners are represented by two-node connector elements which are assigned the force-displacement characteristics determined by local models. The behavior of the wing box is simulated for bending and twisting loads applied together with an increased temperature and the distribution of fastener forces and the progressive fastener failure is studied. It is shown that the fastener forces caused by the temperature difference are of significant magnitude and should be taken into account in the design of hybrid aircraft structures. It is concluded that, the account of the non-linear response of the joints results in a less conservative load distribution at ultimate failure load.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Bolted joints, Composite-aluminum, Finite element modeling, Hybrid wing structures
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-91893 (URN)10.1016/j.compstruct.2013.10.056 (DOI)000331671700020 ()
    Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved
    Download full text (pdf)
    Strength analysis and modeling of hybrid composite-aluminum aircraft structures
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  • 48.
    Kapidzic, Zlatan
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Nilsson, Larsgunnar
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Ansell, Hans
    Saab AB, Linköping, Sweden.
    Conceptual studies of a composite-aluminum hybrid wing box demonstrator2014In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 32, no 1, p. 42-50Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of two different hybrid composite-aluminum concepts applied to a winglike structure which is exposed to mechanical  and thermal load. The aim of the study is to determine the most suitable  hybrid concept to later on be used in structural fatigue and static testing. In both concepts, the mass is optimized with respect to two different sets of requirements, one of which is currently in use in the fighter aircraft industry and one which is a modified version of the current requirement set. The issues considered in the study are mass, thermal behavior, buckling, bolted joints, failure criteria and fatigue damage, and they are examined in the frame of both requirement sets. The results clearly indicate the order of criticality between the different criteria in the different parts of each concept. Also, the comparison of two requirement sets gives an idea of the degree of influence of the modified criteria on the hybrid concepts and their mass. Based on the mass and the structural behavior in a thermal-mechanical loading one of the hybrid concepts is chosen for further studies and testing.

  • 49.
    Kapidzic, Zlatan
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Nilsson, Larsgunnar
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Ansell, Hans
    Saab AB, Linköping, Sweden.
    Finite element modeling of mechanically fastened composite-aluminum joints in aircraft structures2014In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 109, p. 198-210Article in journal (Refereed)
    Abstract [en]

    A three-dimensional, solid finite element model of a composite-aluminum single-lap bolted joint with a countersunk titanium fastener is developed. The model includes progressive damage behavior of the composite and a plasticity model for the metals. The response to static loading is compared to experimental results from the literature. It is shown that the model predicts the initiation and the development of the damage well, up to failure load. The model is used to evaluate the local force-displacement responses of a number of single-lap joints installed in a hybrid composite-aluminum wing-like structure. A structural model is made where the fasteners are represented by two-node connector elements which are assigned the force-displacement characteristics determined by local models. The behavior of the wing box is simulated for bending and twisting loads applied together with an increased temperature and the distribution of fastener forces and the progressive fastener failure is studied. It is shown that the fastener forces caused by the temperature difference are of significant magnitude and should be taken into account in the design of hybrid aircraft structures. It is concluded that, the account of the non-linear response of the joints results in a less conservative load distribution at ultimate failure load.

  • 50.
    Karpur, Anoop
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    Ontology Information Processing toMatrix-Based Approaches for ConceptualDesign2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis aims to develop a methodology to translate an ontology to a matrixbased methods that is case independent. In the larger picture this is one of manycomplexities in systems engineering approach. The focus in this work is in the domainof conceptual design, hence, matrix based methods that are most suitable for it areinvestigated. The flexible nature of the ontology always allows for expansion withnew information about the concepts, and from that perspective a parsing scriptwas developed to extract information from the ontology, it was also designed to beflexible. The script can be used to extract any desired type of information by alteringa few keywords as inputs. The advantage is that the same structure of the script canbe used to extract information from many different ontologies.Using this method the matrices relevant for conceptual design were formulated.These matrices were further compared to each other. Also, a few recommendationswere given for the improvement of the method to adapt towards high fidelity. Thecurrent method is capable of solving problems with low fidelity, however this formsa basis to expand the method to high fidelity problems.

    Download full text (pdf)
    Ontology to matrix
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