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  • 51.
    Andersson, Lars-Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Applied Mathematics.
    Klarbring, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Quasi-static Frictional Contact of Discrete Mechanical Structures2000In: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 19, p. S61-S67Article in journal (Refereed)
  • 52.
    Andersson, Lars-Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Applied Mathematics.
    Klarbring, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Barber, J.R.
    Department of Mechanical Engineering University of Michigan.
    Ciavarella, M.
    CEMEC-PoliBA.
    On the existence and uniqueness of steady state solutions in thermoelastic contact with frictional heating2005In: Proceedings of the Royal Society of Edinburgh. Section A Mathematics, ISSN 0308-2105, E-ISSN 1473-7124, Vol. 461, no 2057, p. 1261-1282Article in journal (Refereed)
    Abstract [en]

    It is well known that contact and friction in thermoelasticity result in mathematical problems which may lack solutions or have multiple solutions. Previously, issues related to thermal contact and issues related to frictional heating have been discussed separately. In this work, the two effects are coupled. Theorems of existence and uniqueness of solutions in two or three space dimensions are obtained - essentially extending, to frictional heating, results due to Duvaut, which were built on Barber's heat exchange conditions. Two qualitatively different existence results are given. The first one requires that the contact thermal resistance goes to zero at least as fast as the inverse of the contact pressure. The second existence theorem requires no such growth condition, but requires instead that the frictional heating, i.e. the sliding velocity times the friction coefficient, is small enough. Finally, it is shown that a solution is unique if the inverse of the contact thermal resistance is Lipschitz continuous and the Lipschitz constant, as well as the frictional heating, is small enough.

  • 53.
    Andersson, Lars-Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Applied Mathematics.
    Klarbring, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Mechanics.
    Barber, J.R.
    University of Michigan.
    Ciavarella, M.
    Politecnio di Bari.
    Thermoelastic Contact with Frictional Heating2006In: Nonsmooth Mechanics and Analysis,2003, New York: Springer Science+business Media, inc. , 2006, p. 61-Conference paper (Refereed)
  • 54.
    Andersson, Maria
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Cooperation in local electricity markets: modelling of technical measures1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents a system analysis for co-operation in local electricity markets including distributors and customers. The purpose of co-operation is to minimise the system cost of local markets by introducing system measures, such as end-use measures and municipal co-generation plants. Co-operation will strengthen the position of local markets in the national as well as future international electricity markets. With end-use measures local markets will achieve flexibility, additional reserve capacity and ability to avoid sudden large costs for peak loads. Biomass-fired cogeneration plants can become of great importance in an international market. In Sweden there is a simultaneous demand for electricity and district heating, many local markets already include district heating systems and there are major forest areas which can contribute with renewable fuel. The system analysis is partly based on the simulation model (INDSIM) and the linear programming model (MODEST). The simulation model has been further developed (STRATO) to include calculation of system costs. Shadow price analysis has been developed in order to study incentives for system measures. Calculation procedures have been developed that describe cooperation between distributor and customer. Six case studies of a selection of real, existing local markets in Sweden are presented. The studies show the potential economical effects of co-operation measured by system costs and shadow prices. Co-operation has been considered between demand- and supply-side, electricity- and district heating systems and also between different time periods. In a typical local market with 90 000 inhabitants, if end use measures are introduced without cooperation the system cost of the distributor will increase by 14 million SEK for a time period of 25 years. If instead end-use measures are introduced in co-operation, together with a biomass-fired cogeneration plant, the system cost of the local market will be reduced by 444 million SEK. Furthermore, the use of biomass in the local market is increased from 36 to 72 % while the use of oil is decreased from 34 to 1%. Another case study of another local market (50 000 inhabitants) shows that end-use measures will reduce the system cost (excluding investment costs) of an industry by 50 % corresponding to 1.3 million SEK for one year. The end-use measures imply reduced power demand during peak load periods in the local market and increased power demand during non- peak load periods.

    List of papers
    1. Cost-effective energy system measures studied by dynamic modelling
    Open this publication in new window or tab >>Cost-effective energy system measures studied by dynamic modelling
    1993 (English)In: 2nd International Conference on Advances in Power System Control, Operation and Management, APSCOM-93., London: Institution of Electrical Engineers (IEE), 1993, Vol. 1, p. 448-455Conference paper, Published paper (Refereed)
    Abstract [en]

    In a national electricity system there often exists a great potential for increasing the cost-efficiency of the electricity use. However, if the economic incentives for improving the use of the system are too weak, it is most likely that this potential will not be utilised. If electricity tariffs reflect real electricity costs, over the year and the day, cost-effective incentives will arise for introducing energy system measures that will reduce the energy system cost considerably. This paper presents two energy system analyses of an existing Swedish municipal energy system. The analyses are carried out with a simulation model for electricity use in industrial energy systems, and an optimisation model that is based on linear programming.<>

    Place, publisher, year, edition, pages
    London: Institution of Electrical Engineers (IEE), 1993
    Series
    IEE conference publication, ISSN 0537-9989 ; 388
    Keywords
    digital simulation, economics, electricity supply industry, industries, linear programming, power consumption, power system analysis computing, tariffs, dynamic modelling, cost-efficiency, economic incentives, costs, municipal energy system, industry, optimisation, digital simulation model, Sweden, power systems, Simulation, Power industry, Power demand
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-165082 (URN)0852965699 (ISBN)
    Conference
    2nd International Conference on Advances in Power System Control, Operation and Management, APSCOM-93, Hong Kong, December 7-10 1993
    Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-04-23Bibliographically approved
    2. Energy system cost reduction as a result of end-use measures and the introduction of a biomass-fired co-generation plant
    Open this publication in new window or tab >>Energy system cost reduction as a result of end-use measures and the introduction of a biomass-fired co-generation plant
    1993 (English)In: International Conference on Renewable Energy - Clean Power 2001: 17-19 November 1993, London, London: Institution of Electrical Engineers (IEE), 1993, no 385, p. 37-42Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper will describe an energy system analysis of an existing Swedish municipality of 90 000 inhabitants. The analysis, which is performed by using an optimization model will show what energy system measures that should be introduced to minimize the total energy system cost. In the existing municipality a local utility distributes heat, for the district heating system, and electricity. The heat is generated by the utility and the electricity is purchased from a large power producer.

    Place, publisher, year, edition, pages
    London: Institution of Electrical Engineers (IEE), 1993
    Series
    IEE conference publication, ISSN 0537-9989 ; 385
    Keywords
    Cogeneration plants, District heating, Electric utilities, Mathematical models, Optimization, Biomass, End use measure, Renewable fuel, Systems analysis
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-165081 (URN)2-s2.0-0027718829 (Scopus ID)0852966059 (ISBN)
    Conference
    International Conference on Renewable Energy - Clean Power 2001, London, 17-19 November 1993
    Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-04-23Bibliographically approved
    3. Shadow prices for heat generation in time-dependent and dynamic energy systems
    Open this publication in new window or tab >>Shadow prices for heat generation in time-dependent and dynamic energy systems
    1994 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 19, no 12, p. 1205-1211Article in journal (Refereed) Published
    Abstract [en]

    Shadow prices for heat generation are used to study the impact of changes in heat demand on the total system cost of an existing district-heating system in Sweden. The energy system may be considered to be both dynamic, because there is energy storage, and time-dependent since the electricity tariff is time-differentiated and the heat demand varies over the year and day. The energy system has been analysed with and without energy storage. The analysis shows that despite a reduction in system cost, the use of energy storage can result in higher shadow prices for heat generation in some time periods.

    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-165079 (URN)10.1016/0360-5442(94)90022-1 (DOI)
    Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-04-14
    4. Cost-effective incentives for cooperation between participants in the electricity market
    Open this publication in new window or tab >>Cost-effective incentives for cooperation between participants in the electricity market
    1996 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 54, no 4, p. 301-313Article in journal (Refereed) Published
    Abstract [en]

    In the Swedish electricity system there is a great potential for increasing the cost efficiency of electricity use. Today economic incentives, offered for instance by existing electricity tariffs, are too weak to improve the use of the system. On the Swedish electricity market, there are at least three different participants, the power producer, the distributor and the customer. Today these participants act separately owing to low awareness of the costs for electricity over the year and the day. If the participants are aware of the real electricity costs, cost-effective incentives for cooperation will arise. When participants cooperate, the introduction of end-use measures will reduce system costs for those participants that are involved in cooperation. We present a system analysis for cooperation between distributor and customers. We also present results from a project, where behaviours of an existing distributor and existing customers have been analysed. The results show that there exist cost-effective incentives for cooperation when end-use measures are introduced.

    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-165077 (URN)10.1016/0306-2619(95)00076-3 (DOI)
    Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-04-14
    5. Cost-effective incentives for end-use measures in a Swedish municipality
    Open this publication in new window or tab >>Cost-effective incentives for end-use measures in a Swedish municipality
    1996 (English)In: Proceedings of the International Symposium [on] Efficiency, Costs, Optimization, Simulation and Environmental Aspects of Energy Systems: ECOS'96, Stockholm, Sweden, June 25-27, 1996 / [ed] Per Alvfors, Stockholm: KTH Royal Institute of Technology, 1996, p. 557-564Conference paper, Published paper (Refereed)
    Abstract [en]

    If actors on the electricity market cooperate when end-use measures are introduced the energy-system, cost will be reduced considerably. The marginal cost for electricity for the energy system of the actors will show cost effective incentives for introducing end-use measures. We present a system analysis for cooperation between distributors and customers. We also present results from a project where an existing distributor and eleven existing customers within a municipal energy system have been analysed. The customers are various industries, a hospital, an ice hockey arena, a harbour, a water-works, a warehouse, and a radio tower. The results show that the customers have in different end-use measures a power reduction capacity of maximum 8642 kW. With electricity costs of 1994 this corresponds to a reduction in the energy system cost of 2,852,000 SEK for one year. The results also show that for the distributor`s load curve of 1994, the full power reduction capacity can not be used since the peak loads of the five winter months are not so large and distinct. In that case the energy system cost can be reduced by 1,909,000 SEK, which is 67% of the maximum cost reduction. The end-use measures that are cost effective in this municipal energy system are load management and electricity generation in reserve power plants. We have also studied the profitability for introducing bivalent heating systems based on oil and electricity for heat loads that originally are based on oil. However, with existing electricity and oil costs there are no incentives for increasing the electricity use during non-peak load periods with bivalent heating systems.

    Place, publisher, year, edition, pages
    Stockholm: KTH Royal Institute of Technology, 1996
    Series
    Trita-KET, ISSN 1104-3466 ; 52
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-165080 (URN)917170664X (ISBN)
    Conference
    International Symposium on Efficiency, Costs, Optimizations, Simulation and Environmental Aspects of Energy Systems, Stockholm, June 25-27, 1996
    Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-04-14Bibliographically approved
    Download full text (pdf)
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  • 55.
    Andersson, Maria
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Cost-effective incentives for local electric utilities and industries in co-operation: modelling of technical measures1993Licentiate thesis, monograph (Other academic)
    Abstract [en]

    In the Swedish electricity system there is a great potential for increasing the cost efficiency of the electricity use. However, today the economic incentives, offered for instance by existing electricity rates, are too weak to improve the use of the system. On the Swedish electricity market there are, at least, three different actors, the power producer, the distributor and the customer. Today these actors act separately due to low awareness of the costs for electricity generation, over the year and the day. If the actors are aware of the real electricity costs, cost-effective incentives will arise to introduce energy system measures that will reduce the energy system cost considerably. The thesis presents two energy system analyses of an existing Swedish municipality. The first analysis deals with the introduction of industrial end-use measures, with the local utility’s existing electricity rates as boundary conditions. The analysis is carried out with a simulation model for electricity use in industries. The second analysis deals with the introduction of energy system measures, on the municipal supply-side and demand-side, when the local electric utility and the customers are regarded as one system. The analysis is carried out with an optimization model, that is based on linear programming. The results show that if 17 industries introduce end-use measures, with the existing electricity rates as boundary conditions, their energy system costs will be reduced by 12 MSEK for a time period of 10 years, whereas the local utility will increase its energy system cost by 6 MSEK. However, if there is a co-operation between the local electric utility and the customers, their joint energy system cost will be reduced by 330 MSEK for a time period of 10 years.

  • 56.
    Andersson, Maria
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Shadow prices for heat generation in time-dependent and dynamic energy systems1994In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 19, no 12, p. 1205-1211Article in journal (Refereed)
    Abstract [en]

    Shadow prices for heat generation are used to study the impact of changes in heat demand on the total system cost of an existing district-heating system in Sweden. The energy system may be considered to be both dynamic, because there is energy storage, and time-dependent since the electricity tariff is time-differentiated and the heat demand varies over the year and day. The energy system has been analysed with and without energy storage. The analysis shows that despite a reduction in system cost, the use of energy storage can result in higher shadow prices for heat generation in some time periods.

  • 57.
    Andersson, Maria
    et al.
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Björk, Curt
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Karlsson, Björn
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Cost-effective energy system measures studied by dynamic modelling1993In: 2nd International Conference on Advances in Power System Control, Operation and Management, APSCOM-93., London: Institution of Electrical Engineers (IEE), 1993, Vol. 1, p. 448-455Conference paper (Refereed)
    Abstract [en]

    In a national electricity system there often exists a great potential for increasing the cost-efficiency of the electricity use. However, if the economic incentives for improving the use of the system are too weak, it is most likely that this potential will not be utilised. If electricity tariffs reflect real electricity costs, over the year and the day, cost-effective incentives will arise for introducing energy system measures that will reduce the energy system cost considerably. This paper presents two energy system analyses of an existing Swedish municipal energy system. The analyses are carried out with a simulation model for electricity use in industrial energy systems, and an optimisation model that is based on linear programming.<>

  • 58.
    Andersson, Maria
    et al.
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Karlsson, Björn
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Cost-effective incentives for cooperation between participants in the electricity market1996In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 54, no 4, p. 301-313Article in journal (Refereed)
    Abstract [en]

    In the Swedish electricity system there is a great potential for increasing the cost efficiency of electricity use. Today economic incentives, offered for instance by existing electricity tariffs, are too weak to improve the use of the system. On the Swedish electricity market, there are at least three different participants, the power producer, the distributor and the customer. Today these participants act separately owing to low awareness of the costs for electricity over the year and the day. If the participants are aware of the real electricity costs, cost-effective incentives for cooperation will arise. When participants cooperate, the introduction of end-use measures will reduce system costs for those participants that are involved in cooperation. We present a system analysis for cooperation between distributor and customers. We also present results from a project, where behaviours of an existing distributor and existing customers have been analysed. The results show that there exist cost-effective incentives for cooperation when end-use measures are introduced.

  • 59.
    Andersson, Maria
    et al.
    Linköping University, Department of Mechanical Engineering. Linköping University, Faculty of Science & Engineering.
    Karlsson, Björn
    Linköping University, Department of Mechanical Engineering. Linköping University, Faculty of Science & Engineering.
    Cost-effective incentives for end-use measures in a Swedish municipality1996In: Proceedings of the International Symposium [on] Efficiency, Costs, Optimization, Simulation and Environmental Aspects of Energy Systems: ECOS'96, Stockholm, Sweden, June 25-27, 1996 / [ed] Per Alvfors, Stockholm: KTH Royal Institute of Technology, 1996, p. 557-564Conference paper (Refereed)
    Abstract [en]

    If actors on the electricity market cooperate when end-use measures are introduced the energy-system, cost will be reduced considerably. The marginal cost for electricity for the energy system of the actors will show cost effective incentives for introducing end-use measures. We present a system analysis for cooperation between distributors and customers. We also present results from a project where an existing distributor and eleven existing customers within a municipal energy system have been analysed. The customers are various industries, a hospital, an ice hockey arena, a harbour, a water-works, a warehouse, and a radio tower. The results show that the customers have in different end-use measures a power reduction capacity of maximum 8642 kW. With electricity costs of 1994 this corresponds to a reduction in the energy system cost of 2,852,000 SEK for one year. The results also show that for the distributor`s load curve of 1994, the full power reduction capacity can not be used since the peak loads of the five winter months are not so large and distinct. In that case the energy system cost can be reduced by 1,909,000 SEK, which is 67% of the maximum cost reduction. The end-use measures that are cost effective in this municipal energy system are load management and electricity generation in reserve power plants. We have also studied the profitability for introducing bivalent heating systems based on oil and electricity for heat loads that originally are based on oil. However, with existing electricity and oil costs there are no incentives for increasing the electricity use during non-peak load periods with bivalent heating systems.

  • 60.
    Andersson, Maria
    et al.
    Linköping University, Department of Mechanical Engineering.
    Kristofferson, Hanna
    Linköping University, Department of Mechanical Engineering.
    Structural Optimization of Product Families: With Application to Vehicle Body Structures2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Some products share one or two modules and while developing these products, structural optimization with stiffness as the objective function can be a useful tool. There might be no or very little CAD-data available in the pre-development phase and it is not certain that existing designs can be, or is desirable to use as a reference. The main objective of this thesis is to establish an accurate and fast-to-use methodology which can be utilized while developing new cars.

    In this thesis, the Volvo products S40, V50 and C70 serve as a basis for this case study. All the models are beam structures and the masses of components are added as point and line masses. Several optimization analyses are performed on one or three products exposed to seven load cases. Additional analyses with shell elements, more simplified models and changed load case balance achieved by normalization of the different load case compliances are also studied to investigate how these factors influence the results.

    Analyses show that front crash to a great extent dominates the results while normalization increases the influence of the remaining load cases. Since front crash is dominating and the front area is shared in all products, the performance is remarkably similar when three products are optimized compared to separate analyses of one product. Analysis of models without added point or line masses gives a result which greatly differs from previous results and therefore shows that added masses are required. The methodology is applicable to develop products and detect new load paths through the car.

    Download full text (pdf)
    FULLTEXT01
  • 61.
    Andersson, Nils-Eric
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    High speed machine metallic structures NFFP-344 WE 2.22002Report (Other academic)
  • 62.
    Andersson, Nils-Eric
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Structure and properties of thick plate and near surface properties after high speed machining af AA70102003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Using thick plates instead of forgings in the aircraft industry for integral construction of load carrying components is becoming more and more practice. The reasons are shorter lead-times from design of a modified or totally new component to introduction in an aircraft and smaller variations in properties for plate compared to forging. The concept of integral construction also reduces the assembly time. The complex shaped components are prepared by machining pieces of thick plate. The thicker the plate the larger components can be made in one piece. Machining components from blocks of material cut from thick plate means removal of a lot of material compared to machining of near final shape forgings. A change in machining concept to high speed machining leads to higher productivity and makes thin walled sections possible to manufacture due to decreased cutting forces.

    Variation of through thickness structure and properties of 7010-T7451/2 as 100, 150 and 200 mm thick plates has been investigated. Through thickness crystallographic texture, degree of recrystallisation, distribution of inclusions, chemical composition and grain size has been mapped out. The observed structure is taken into account in order to explain variations of properties like yield strength; fracture toughness and fatigue crack growth resistance. Equipment used in the work of characterising the structure has been EBSP, SEM, X-ray diffraction and optical microscopy. Equipment used for evaluating mechanical properties is screw machines, servo hydraulic machines and hardness indentors.

    The plates show a strong through thickness texture gradient that influence the yield strength. The yield strength is also dependent on chemical composition and quench rate. Recrystallisation did not show any significant influence on yield strength or fracture toughness. The grain morphology together with quench rate is of importance for the fracture toughness and the fatigue crack growth resistance.

    Properties of down cut milled surfaces on thin sections using a conventional machining concept and the concept of high speed machining at various cutting speeds have been compared. The same has been done for facemilled surfaces using conventional tools and inserts at cutting speeds varying from 500 m/min up to 5000 m/min. The property of most interest is the high cycle fatigue strength. The influence of surface roughness, residual stresses and hardness on the fatigue strength has been investigated. In order to try to gain a little more information about the near surface properties x-ray diffraction studies at grazing angle incidence has been undertaken.

    List of papers
    1. The influence of hot rolling on the variation of through thickness structure of AA7010 thick plates
    Open this publication in new window or tab >>The influence of hot rolling on the variation of through thickness structure of AA7010 thick plates
    1996 (English)In: Thermomechanical processing in theory, modelling and practice [TMP]2: proceedings of an International Conference organised in celebration of the 75th anniversary of the Swedish Society for the Materials Technology, 1996, p. 284-289Conference paper, Published paper (Other academic)
    Abstract [en]

    The variation of through thickness structure and yield strength of AA7010-T7451 thick plate has been investigated. Grain sizes at different depths were determined qualitatively by using optical microscopy. Texture measurements were carried out using X-ray technique at the same depths as grain size studies and tensile property tests have been performed. EBSP techdque has been used to compare the degree of recovered and recrystallized grain structure at different depths. Tensile testing determined through thickness variations in yield strength. The well known W shape of longitudinal yield strength variation through the thickness was not observed. The influence of texture on the yield strength measured is discussed.

    Keywords
    Aluminium, texture, an isotropy, yield strength, plate, Taylor factor
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86812 (URN)91-630-5421-3 (ISBN)
    Conference
    Thermo- Mechanical Processing Theory, Modelling and Practice (TMPT)2, Stockholm, Sweden 4-6 September
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2013-01-07
    2. The variation of through thickness properties and structure of AA7010 thick plate
    Open this publication in new window or tab >>The variation of through thickness properties and structure of AA7010 thick plate
    1997 (English)In: International Conference on Thermomechanical Processing of Steel and Other Materials 1997: THERMEC '97 / [ed] T. Chandra and T. Sakai, 1997, p. 941-949Conference paper, Published paper (Refereed)
    Abstract [en]

    The variation of through thickness structure and yield strength of AA7010-T7451 100 and 150 mm thick plate was investigated. Grain sizes at different depths were determined by using optical microscopy and EBSP maps. Texture measurements were carried out, using X-ray technique and EBSP, at the same depths as grain size studies and tensile property tests were performed. EBSP technique was used to compare degree of recovered and recrystallized grain structure at different depths. Tensile testing and hardness measurements reveal through thickness variations in yield strength and hardness. Variations in composition through the thickness are also possible. The influence of texture on yield strength was discussed.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86813 (URN)0-87339-377-5 (ISBN)
    Conference
    THERMEC'97, International Conference on Thermomechanical Processing of Steels & Other Materials, University of Wollongong, Australia, 7-11 July, 1997
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2013-01-07
    3. Through thickness fracture toughness variations of AA7021 thick plate
    Open this publication in new window or tab >>Through thickness fracture toughness variations of AA7021 thick plate
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    In this work, a variation of fracture toughness as a function of position and orientation in commercial thick plates of a high strength aluminium alloy has been investigated. Structural and mechanical property variations have been investigated in order to understand the result of the fracture toughness measurements. 100, 150 and 200 mm thick plates of the aluminium alloy AA7010 were studied. The material was averaged and stress relieved by stretching (100 and 150 mm) and cold compression (200 mm), T7451/52. The material studied is frequently used to produce load-carrying airframe components. The knowledge of fracture properties throughout the thick plates is of importance since components are machined from them. The understanding of the varying fracture properties is valuable for development of material and or processes for producing thick plate of high strength aluminium alloys. It is of course also important to know the limitations of the thick plate material and the best way to produce a certain component from a piece of the plate material. Investigated parameters influencing fracture properties are inclusions, recrystallisation, yield strength, chemical composition and quench rate.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86816 (URN)
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2013-01-07
    4. Fatigue crack growth rate in commercial thick plates of AA7010
    Open this publication in new window or tab >>Fatigue crack growth rate in commercial thick plates of AA7010
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    A mapping of fatigue crack growth rates in commercial thick plates of a high strength aluminium alloy, AA7010-T7451/52, has been done. The investigated plate thicknesses were 100, 150 and 200 mm. Material from near edge and mid-width at near surface and mid-thickness has been investigated. Measurements of crack length have been perfonned using DC potential drop. Cyclic condensation is used in order to be able to investigate local crack growth after fracture. Influence of crack closure, crack branching and slow growing side cracks on fatigue crack growth rate of S-L and L-T oriented CT specimens are discussed. S-L specimens show the highest fatigue crack growth rates. Beach marks on the fracture surface due to the cyclic condensation reveals locally straight crack fronts. A difference in growth rate between near surface and mid-thickness positioned L-T specimens are found. At a nominal ΔK of - 7 MPa√m the mid-thickness samples showed a sudden crack growth rate acceleration. The result of the investigation is explained in tenns of variations in structure, which is a function of position in the plates and plate thickness.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86819 (URN)
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2013-01-07
    5. Property comparison of thin walled sections machined using high speed machining and conventional machining
    Open this publication in new window or tab >>Property comparison of thin walled sections machined using high speed machining and conventional machining
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The influence of two different machining concepts has been compared. Pockets were machined in a thick plate of AA7010-T7451 by using a high speed machining concept at three different cutting speeds and a conventional machining concept. The pockets were machined using down cut milling and of the remaining thin walls of material fatigue samples were taken out. Some high-speed machined surfaces were anodized using chromic acid in order to see if differences in fatigue properties remained after this surface process. Fatigue properties at constant amplitude and random spectra loading were tested. Properties like residual stress, surface roughness; peak broadening at grazing incidence and micro hardness of machined surfaces were investigated and correlated to the fatigue results. A low cutting speed using the high speed machining or the conventional machining concept yielded the best fatigue properties when fatigue initiation is of concern. The higher fatigue strength is not explained by the residual stresses measured at the machined surfaces using chromium and copper radiation or by the somewhat larger surface roughness. The penetration depth of the residual stresses was found to be higher at high cutting speeds. Fatigue initiation took most often place at near surface iron-rich inclusions. The points of fatigue initiation were not found to differ for different machining concepts and cutting speeds.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86820 (URN)
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2013-01-07
    6. Face milling of AA7010 at high cutting speeds
    Open this publication in new window or tab >>Face milling of AA7010 at high cutting speeds
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Face milling using different commercial tools and inserts at varying cutting speeds on a high strength aluminium alloy has been performed. The surface integrity of the machined samples has been investigated in terms of surface roughness, residual stresses, hardness and peak broadening from x-ray diffraction at grazing angle incidence. Some fatigue testing of the machined surfaces has been done. The cutting chips from the different machining parameters are investigated and compared to one another. The results show a strong influence of tool insert on surface roughness, residual stress, peak broadening, and hardness profile and fatigue properties. The influence of cutting speed on the surface integrity is much smaller. The cutting speed does however influence the size and shape of the cutting chips. There is also a general decrease in peak broadening from x-ray diffraction very near the machined surface after high cutting speeds. This could be explained by a higher local heating of the work piece at very high cutting speeds.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86822 (URN)
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2013-01-07
  • 63.
    Andersson, Nils-Eric
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Fatigue crack growth rate in commercial thick plates of AA7010Manuscript (preprint) (Other academic)
    Abstract [en]

    A mapping of fatigue crack growth rates in commercial thick plates of a high strength aluminium alloy, AA7010-T7451/52, has been done. The investigated plate thicknesses were 100, 150 and 200 mm. Material from near edge and mid-width at near surface and mid-thickness has been investigated. Measurements of crack length have been perfonned using DC potential drop. Cyclic condensation is used in order to be able to investigate local crack growth after fracture. Influence of crack closure, crack branching and slow growing side cracks on fatigue crack growth rate of S-L and L-T oriented CT specimens are discussed. S-L specimens show the highest fatigue crack growth rates. Beach marks on the fracture surface due to the cyclic condensation reveals locally straight crack fronts. A difference in growth rate between near surface and mid-thickness positioned L-T specimens are found. At a nominal ΔK of - 7 MPa√m the mid-thickness samples showed a sudden crack growth rate acceleration. The result of the investigation is explained in tenns of variations in structure, which is a function of position in the plates and plate thickness.

  • 64.
    Andersson, Nils-Eric
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Fatigue crack growth rate in thick plates of 70101999In: Fatigue 99: Proceedings of the 7th International Fatigue Conference / [ed] X. R. Wu, 1999Conference paper (Refereed)
  • 65.
    Andersson, Nils-Eric
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Property comparison of thin walled sections machined using high speed machining and conventional machiningManuscript (preprint) (Other academic)
    Abstract [en]

    The influence of two different machining concepts has been compared. Pockets were machined in a thick plate of AA7010-T7451 by using a high speed machining concept at three different cutting speeds and a conventional machining concept. The pockets were machined using down cut milling and of the remaining thin walls of material fatigue samples were taken out. Some high-speed machined surfaces were anodized using chromic acid in order to see if differences in fatigue properties remained after this surface process. Fatigue properties at constant amplitude and random spectra loading were tested. Properties like residual stress, surface roughness; peak broadening at grazing incidence and micro hardness of machined surfaces were investigated and correlated to the fatigue results. A low cutting speed using the high speed machining or the conventional machining concept yielded the best fatigue properties when fatigue initiation is of concern. The higher fatigue strength is not explained by the residual stresses measured at the machined surfaces using chromium and copper radiation or by the somewhat larger surface roughness. The penetration depth of the residual stresses was found to be higher at high cutting speeds. Fatigue initiation took most often place at near surface iron-rich inclusions. The points of fatigue initiation were not found to differ for different machining concepts and cutting speeds.

  • 66.
    Andersson, Nils-Eric
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Through thickness fracture toughness variations of AA7021 thick plateManuscript (preprint) (Other academic)
    Abstract [en]

    In this work, a variation of fracture toughness as a function of position and orientation in commercial thick plates of a high strength aluminium alloy has been investigated. Structural and mechanical property variations have been investigated in order to understand the result of the fracture toughness measurements. 100, 150 and 200 mm thick plates of the aluminium alloy AA7010 were studied. The material was averaged and stress relieved by stretching (100 and 150 mm) and cold compression (200 mm), T7451/52. The material studied is frequently used to produce load-carrying airframe components. The knowledge of fracture properties throughout the thick plates is of importance since components are machined from them. The understanding of the varying fracture properties is valuable for development of material and or processes for producing thick plate of high strength aluminium alloys. It is of course also important to know the limitations of the thick plate material and the best way to produce a certain component from a piece of the plate material. Investigated parameters influencing fracture properties are inclusions, recrystallisation, yield strength, chemical composition and quench rate.

  • 67.
    Andersson, Nils-Eric
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Björklund, Stefan
    Linköping University, Department of Mechanical Engineering, Production Engineering. Linköping University, The Institute of Technology.
    Face milling of AA7010 at high cutting speedsManuscript (preprint) (Other academic)
    Abstract [en]

    Face milling using different commercial tools and inserts at varying cutting speeds on a high strength aluminium alloy has been performed. The surface integrity of the machined samples has been investigated in terms of surface roughness, residual stresses, hardness and peak broadening from x-ray diffraction at grazing angle incidence. Some fatigue testing of the machined surfaces has been done. The cutting chips from the different machining parameters are investigated and compared to one another. The results show a strong influence of tool insert on surface roughness, residual stress, peak broadening, and hardness profile and fatigue properties. The influence of cutting speed on the surface integrity is much smaller. The cutting speed does however influence the size and shape of the cutting chips. There is also a general decrease in peak broadening from x-ray diffraction very near the machined surface after high cutting speeds. This could be explained by a higher local heating of the work piece at very high cutting speeds.

  • 68.
    Andersson, Nils-Eric
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Zeng, Xiao-Hu
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    The influence of hot rolling on the variation of through thickness structure of AA7010 thick plates1996In: Thermomechanical processing in theory, modelling and practice [TMP]2: proceedings of an International Conference organised in celebration of the 75th anniversary of the Swedish Society for the Materials Technology, 1996, p. 284-289Conference paper (Other academic)
    Abstract [en]

    The variation of through thickness structure and yield strength of AA7010-T7451 thick plate has been investigated. Grain sizes at different depths were determined qualitatively by using optical microscopy. Texture measurements were carried out using X-ray technique at the same depths as grain size studies and tensile property tests have been performed. EBSP techdque has been used to compare the degree of recovered and recrystallized grain structure at different depths. Tensile testing determined through thickness variations in yield strength. The well known W shape of longitudinal yield strength variation through the thickness was not observed. The influence of texture on the yield strength measured is discussed.

  • 69.
    Andersson, Roger
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    Ask, Per
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Cross-sectional changes in an asymmetric tube with bearing on non-invasive pressure measurements2003In: Technology and Health Care, ISSN 0928-7329, E-ISSN 1878-7401, Vol. 11, no 1, p. 11-20Article in journal (Refereed)
    Abstract [en]

    This study aims at investigating the radial dimensional changes, as a result of an applied intraluminal pressure for an elastic tube with non-uniform cross section. The study is related to a method for non-invasive pressure measurement using the extracorporeal tube as part of the sensor. The intended application is for monitoring of pressure in the blood and dialysate tubes during haemodialysis. The intention is to find a tube cross-section geometry that results in an expansion of the tube so that it is suitable to use as a component in a pressure sensor. The tube should have high radial compliance and expand in a well-defined manner to be able to transfer the intraluminal pressure to a transducer element sensing the radial force. Radial expansion was studied experimentally for tubes with different cross-section geometries. For small tube expansions the resolution in the experimental measurements was not sufficient to study the radial expansion. In this case, numerical simulation was performed. We conclude that a tube with essentially elliptic outer surface and circular inner surface, with a relation of 1:2 between the size of the thin and thick wall, results in a radial expansion upon application of pressure indicating that this tube is suitable for use as part of a sensor.

  • 70.
    Andersson, Roger
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Pressure sensed non-invasively directly on the extra corporeal blood line tubes2001In: Int Conference of the IEEE Engineering in Medicine and Biology Society,2001, 2001Conference paper (Refereed)
  • 71.
    Andrén, Pia
    et al.
    IAV/magisterutbildning Linköpings universitet.
    Eklund, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Industrial Ergonomics.
    Hur påverkar fastighetsboxar brevbärares arbetsmiljö2004Report (Other academic)
  • 72.
    Antoni, Marc
    Linköping University, Department of Mechanical Engineering, Quality Technology and Management. Linköping University, The Institute of Technology.
    Inter-project learning: a quality perspective2000Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The development of most sectors in Western economies goes towards a more flexible, project-oriented way of doing business. However, the vast majority of projects exceed their planned budget in terms of time, financial resources and other resources. In companies, which organize work in the form of projects, reinventions of the wheel can also often be observed. One reason for problems of project management is learning deficiencies. Most projects have repetitive components, which make an institutionalization of them useful. However, any formalization should be seen in a balanced relation to the renewal potential of projects.

    The research presented in this thesis aims to gain insight into enabling factors of Inter-Project Learning. This aim is pursued via theoretical literature studies and the study of organizations. The thesis consists of a frame and four papers covering different aspects of Inter-Project Learning. The areas discussed in the frame and the papers are Project Management, Profound Knowledge. Organizational Learning and Process Management.

    In the literature it was found that Inter-Project Learning is usually not planned for, which is supported by empirical evidence. Inter-Project Learning activities partly gave the impression of being seen as pleasant side effects. A central challenge for Inter-Project Learning is the understanding and perception of time in projects, since members of a temporary organization have partly other goals than members of the permanent parental organization. Deming's concept of Profound Knowledge was found to be one useful way of achieving a better understanding of the problems surrounding Inter-Project Learning.

    Experience from projects can be preserved in a process organization supporting Inter-Project Learning. However, it was found that the relation between both project and process organization, as well as between project manager and process owner, in practice is often unclear, which can lead to problems.

    Furthermore. a distinction of forms supporting Inter-Project Learning in codification and personalization forms was found to be convenient. These should not be understood as mutually exclusive approaches, but rather as a choice of emphasis. Empirical data suggest that the choice of emphasis is not a static one, but can shift over time.

    Apart of the findings have been combined in a tentative model for Inter­Project Learning, which shall function as a basis for further discussion. improvement and research.

  • 73.
    Antoni, Marc
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    Learning between projects: - in product development contexts -2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A project is often formed with the intention to bring forth a deliverable within a certain time frame. This goal-focus however may lead to suboptimizations on the organizational level. At the same time projects more often than not underperform in a number of aspects, with an especially huge gap in the learning aspect.

    Thus the research questions addressed in this work concern what is done in organizations to foster organizational learning in project-based contexts, how different actions arc implemented and how the relation between the project and the functional organization affects organizational learning. Deming' s profound knowledge structure has been used to structure the theoretical aspects.

    It was found that learning in a project context is not a typical activity and needs to be organized for. The reinvention of the wheel still remains a major, unsolved problem for organizations that develop their products via projects. That is partly due to the fact that a project is a natural forum for learning new things. but not a natural forum for learning from past experience. A central finding of this work is that a systems perspective is necessary in project management contexts. Categories related to learning that have been identified are a category relating to documented knowledge, a category relating to learning in personal interaction and a category regarding organizational aspects.

    Regarding documented knowledge it was found that among practitioners there seems to be an unjustified belief in the ability of documents to solve learning problems of projects. Personal interaction was found to be an effective way for learning, but the risk of information overload by meetings is considerable. Bounded rationality seems to play an important role. As conflicting value systems meet. The forward-orientation, action-focus of projects meets with the long-time perspective of organizational learning.

    Important elements when researching learning between projects are amongst others feedback, learning incentives. modularization, location of project team members. organizational size, inter-project competition, full-time project managers and the formulation of a learning mandate for the project.

  • 74.
    Antoni, Marc
    et al.
    Linköping University, Department of Mechanical Engineering.
    Forsberg, Torbjörn
    Nilsson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Process orientation: the Swedish experience1999In: Total Quality Management and Business Excellence, ISSN 1478-3363, E-ISSN 1478-3371, Vol. 10, no 45, p. 540-547Article in journal (Other academic)
  • 75.
    Antoni, Marc
    et al.
    Robert Bosch GmbH.
    Nilsson-Witell, Lars
    Service Research Center Karlstads universitet.
    Dahlgaard, Jens Jörn
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Quality Technology and Management.
    Inter-project improvement in product development2005In: International Journal of Quality & Reliability Management, ISSN 0265-671X, E-ISSN 1758-6682, Vol. 22, no 9, p. 876-893Article in journal (Refereed)
  • 76.
    Aresu, Emanuela
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Design process management for successful assembly systems2001Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Assembly system design is an important task for a manufacturing company regardless of the nature of its existing assembly activities. However, unlike the product development process, the process of designing assembly systems has not been emphasised.

    The research presented in this thesis aims at identifying and structuring the performance of assembly systems and their design processes, and proposing a framework for identifying important relationships between the results of specific design projects and influencing factors in the field of the design process. These objectives have been accomplished through theoretical and empirical studies. The empirical studies were carried out in the form of an interview study at 15 companies and three case studies at Swedish manufacturing companies both aimed at describing and analysing companies' assembly systems as well as their assembly system design processes.

    A number of characteristics of successful assembly systems have been identified and classified according to the system theory. They have then been structured in a model where the mentioned characteristics have been classified into nine groups indicating the performance of the assembly system. Assembly system performance is represented from a higher level of abstraction by assembly strategy, to a lower level of abstraction by quality, lead time and delivery precision, flexibility, cost and productivity of the assembly system.

    The assembly system design processes have also been investigated and analysed empirically, showing that structured methods are seldom used in the assembly system design process, but mainly experience and knowledge of system designers is utilised. Although larger companies worked more systematically, no specific method for the design of assembly system has been found. The performance of the assembly system design process has been identified and presented in a model with nine performance indicators into three levels, from a higher level of abstraction (design process strategy) to a lower level of abs traction (quality, lead time and delivery precision, flexibility, cost and productivity).

    From the two performance models, an approach to a matrix linking design factors to the design project results has been developed. Examples of the design factors have been given based on research studies in the field of product development, and on the theoretical and empirical studies presented in this thesis. The matrix described is an approach to a tool for the support of production managers and system designers in order to design successful assembly systems.

  • 77.
    Arvidsson, Emma
    et al.
    Linköping University, Department of Mechanical Engineering.
    Ekblad, Emma
    Linköping University, Department of Mechanical Engineering.
    Framtagning av krypmodell för termomekanisk FE-analys av grenrör2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [sv]

    Grenrören i en motor utsätts för stora termiska och mekaniska belastningar, vilka gör att grenrören ofta spricker. Idag kan inte sprickbildningen fullständigt uttydas ur beräkningarna, syftet med arbetet är därför att se om dessa kan förbättras genom att använda en mer avancerad krypmodell än den som används idag.

    Ett förslag till krypmodell har tagits genom att studera ett antal i litteraturen funna modeller. De som valts ut är modeller enligt Norton, Bailey-Norton, Marin-Pao, Picket och Findley. Parametrarna i de olika modellerna har bestämts genom kurvanpassning av enaxliga prov på de aktuella grenrörsmaterialen. Resultaten visar att modellerna enligt Marin-Pao, Picket och Findley alla kan beskriva mätkurvorna nästan exakt. Problem uppstår dock med att man får parametrar som beror av både spänning och temperatur. Av dessa tre modeller anses Marin-Pao vara den bästa, då det är den av de tre som har minst antal parametrar. Utvärderingen ger vidare att Norton är den modell som är enklast, och beaktat över alla prover, den vars resultat bäst ansluter sig till mätdata. Valet görs att gå vidare med både Marin-Paos och Nortons modell.

    De två aktuella modellerna har lagts in som subrutiner till FE-programmet ABAQUS. Tester av modellerna görs först på ett litet kubiskt element och sedan på hela grenröret. Jämförelser görs mellan Norton, Marin-Pao och den modell som används idag – ”Two-layer viscoplasticity model”. Såväl Marin-Paos modell som Nortons beskriver verkligheten bättre än den idag använda modellen och av de båda är Nortons modell den som mest tillfredställande speglar verkligheten. Det är dessutom den modell som är mest stabil och beräkningsmässigt effektivast. Som en rekommendation inför fortsatt arbete föreslås därför användning av Nortons modell, samt ett utökat antal krypprover.

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  • 78.
    Ask, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Brandberg, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Karlsson, Matts
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Modelling and Simulation .
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Wranne, Bengt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Assessment of heart valve function with echocardiography1997In: World Congress on Medical Physics and Biomedical Engineering,1997, 1997, p. 394-394Conference paper (Refereed)
  • 79.
    Ask, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Hök, Bertil
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Teriö, Heikki
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Bioacoustic signals from stenotic tube flow1995In: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 33, p. 669-675Article in journal (Refereed)
  • 80.
    Asplund, Anders
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    How a continuously changing B2B environment influences the selection of suppliers: introducing a model and process approach2004Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Creation of a supply base is perhaps the most important task of the purchasing function. In this creation process, potential suppliers must be identified, analysed and decisions made. Decisions that, in most cases, have direct effects on the company's "bottom line". The tools to support and aid this process are often one-dimensional and assume to a high degree that, in all cases, there is a valid description of the best possible supplier. This research suggests that this is not the case. Which is the best possible supplier is situation specific. This is a fact acknowledged in the literature and by the empirical material. What is missing is a tool to support the supplier selection process from a starting point that each sourcing situation is unique. This research proposes such a process approach and, at the same time, a model for supplier selection.

    The purpose of this study is to analyse and develop the process of, and the criteria for, supplier selection in a sub-tier, business to business context. The research has been initiated by, and had its starting point in, one company (Volvo Aero Corporation) acting in the specific and very demanding environment of the aero-engine industry. The main aim of this research is to give managerial implications for purchasing professionals.

    To be able to ensure that the best possible supplier for a specific situation is selected, the situation has to be analysed. This research proposes a model and process that starts by defining the minimum requirement which a supplier has to fulfil for a purchaser to be convinced that the intended relationship will be successful for the intended period of time. This minimum requirement is called the supplier profile. The business environment, network and market conditions, the.purchasing company 's strategies and the characteristics of the product, service or function to be sourced are identified as influential factors when creating the supplier profile. The results also highlight the need to work cross-functionally when creating the supplier profile and the need to combine different theoretical bases to get a complete picture of the requirements to put on a potential supplier.

  • 81.
    Axelsson, Anders
    Linköping University, Department of Mechanical Engineering.
    Validering av BME - ett verktyg för kartläggning av belastningsergonomi2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [sv]

    I Volvo Personvagnars tillverkningsanläggning i Torslanda utanför Göteborg tillverkas personbilar av flera modeller och en mängd olika varianter av varje modell. I dagsläget är produktivitetskraven höga vilket medför risker för belastningsbesvär eller skador för

    operatörerna som monterar ihop bilen. Således blir belastningsergonomi en viktig del i arbetsmiljöarbetet.

    Man har på Volvo Personvagnars slutmonteringsanläggning i Torslanda utvecklat en beräkningsmodell för att beskriva belastningsergonomin i tillverkningen som man kallar BME (Beräknings Modell Ergonomi). Problemet består i att utvärdera validiteten hos BME utifrån ett

    personalekonomiskt perspektiv, det vill säga huruvida kostnader relaterade till sjukfrånvaro,sjukskrivningar, rehabilitering, personalomsättning och omplaceringar kan knytas till belastningsergonomi med hjälp av BME. Genom litteraturstudier, undersökningar om hur den belastningsergonomiska situationen förändrats sedan BME infördes samt genom studier av hur sjukdomsbilden ser ut kunde samband ställas upp mellan belastningsergonomisk tyngd och

    förekomst av skador.

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  • 82.
    Backlund, Göran
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology. Combitech Systems AB, Linköping, Sweden.
    The effects of modeling requirements in early phases of buyer-supplier relations2000Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This work is an attempt to attack waste of resources during development of embedded systems. Modern systems, in aircraft or automobiles, constantly grow in complexity and also become more integrated. The task of specifying system requirements really shows how crippled the human mind is when we try to master the complexity by the use of natural language. In order to clearly resolve the requirements, other methods need to be employed.

    Focus on system requirements means focus on the early phases of systems development. It is particularly crucial to clearly understand the requirements in collaborative development, since the system requirement specification usually is a part of the contractual agreement. The research questions are: How shall models be used in collaborative systems development? What is the effect of using models?

    The framework of reference for this work is the product development process, collaborative development and requirements analysis. The standard systems development processes are studied and their importance, apart from providing an orderly way of conducting development and establishing a common terminology, is the fact that they are needed as a tool for measuring organizational efficiency. Largely due to complexity, outsourcing of systems development is common in the aircraft industry - the buyer cannot have all required competence in-house. Consequently, parts of the development work is outsourced to suppliers who share risk, and this collaborative development leads to close relations between buyer and supplier. The airworthiness certification process is a contributing factor; it is not easy to change suppliers. The collaborative development relies on commercial contracts where the system requirements are a central part. This motivates focus on the requirements analysis phase; well understood and communicated requirements are a prerequisite for a successful collaborative development project.

    It is also a part of the lean philosophy - always attack waste of resources - to bring in the supplier early, and to focus on the early phases. Good requirements must have specific characteristics, hut if we try to specify complex systems in natural language, the sheer number of requirements represent complexity that limits the overview, and characteristics like completeness, consistency and unambiguity are often violated. Therefore, formal methods are needed for specification since they force the engineers to state the required functionality exactly. There are formalisms available, like Statecharts or ROOMcharts, that can capture the functional behavior of a complex system, and offer testing of the specification since the resulting model is executable.

    Management is responsible for process improvements, hut often lack tools for decision support; justification for investment in a process change. There have, until recently, not existed any tools for simulation of process improvement, for highly iterative processes. Design Structure Matrix is a method used in this work that actually can simulate such processes.

    The use of requirement models in collaborative systems development, and the resulting effect, is studied in two cases. These cases are subprojects in the Gripen fighter program at Saab AB, where two other organizations are suppliers to the projects. One case represents a situation before introduction of modeling requirements, and the other case represents the after situation, since modeling is already a natural way of working in that case. Modeling was tested in one of the cases, within the framework of this study. The results are positive, from both cases, and are summarized as recommendations to future projects. The results prove the current text-based requirement specifications to be inadequate and to cause problems later in systems development.

    Model integration efforts, prior to this work as well as efforts executed in this work, are summed up and result in recommendations to future projects.

    A method for simulating the effects of process improvement was tested on one of the cases. The Design Structure Matrix (DSM) method was applied to a collaborative systems development process, which was derived from interviews in the case studies. The process change studied was the introduction of requirements modeling, and the result was a substantial reduction of total project time. This result was corroborated by study­ ing problem reports in that project, since many of the detected problems were of the kind that they probably had been detected early through modeling of functional requirements. The other case, which early adopted a model-based approach, actually found some design errors, and due to their early detection the result was a reduction of project time. However, it is difficult to account for the problems "that never occurred", since many of them were avoided very early in the project, prior to any problem reporting having been established.

    Finally, a "Digital Mock-Up" room, which is a concept for model-based design currently applied to airframe development, is recommended for carrying over to the systems and software engineering areas. In such rooms the systems development teams can meet around requirements models, performance models, etc. and actually make the models the foundation and design base of their decisions and engineering work.

  • 83.
    Bacos, M P
    et al.
    Office National d'Etudes et de Recherches Aérospatiales, France.
    Josso, P
    Office National d'Etudes et de Recherches Aérospatiales, France.
    Vialas, N
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Poquillon, D
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Pieraagi, B
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Monceau, D
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Nicholls, J R
    Cranfield University, United Kingdom.
    Simms, N
    Cranfield University, United Kingdom.
    Encinas-Oropesa, A
    Cranfield University, United Kingdom.
    Ericsson, Torsten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Stekovic, Svjetlana
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    ALLBATROS advanced long life blade turbine coating systems2004In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 24, no 11-12, p. 1745-1753Article in journal (Refereed)
    Abstract [en]

    The scientific and technological objectives of this program are to increase the efficiency, reliability and maintainability of industrial gas turbine blades and vanes by

    • developing coatings that can warrant a 50 000 h life, i.e. twice that of the usual life, of the hot components (800–1100 °C) even with the use of renewable fuels such as biomass gas or recovery incinerator gas i.e. low-grade fuels with high pollutant levels,

    • characterising advanced existing coatings to assess lifetime and performance of coatings and coated materials,

    • providing material coating data and design criteria to use coating as a design element,

    • increasing the fundamental understanding of the behaviour of coated materials, their degradation, fracture mechanisms and engineering because of the strong need for a mechanism-based modelling of durability.

    These programmes permitted the selection of two reference coatings and the development of two innovative coatings. Concurrently work has been done in order to develop corrosion, oxidation and thermo-mechanical property models. Correlations between coatings development, experimental results and calculations will be discussed.

  • 84.
    Bacos, M-P
    et al.
    Office National DÉtude et de Recherces Aerospatiales Chatillon Cedex France.
    Josso, P
    Office National DÉtude et de Recherces Aerospatiales Chatillon Cedex France.
    Vialas, N
    CIIRMAT Toulouse, France.
    Poquillon, D
    CIRIMAT Toulouse.
    Pierraggi, B
    CIRIMAT Toulouse. France.
    Monceau, D
    CIRIMAT Toulouse, France.
    Nicholls, J R
    Cranfield University Bedford, UK.
    Simms, N
    Cranfield University Bedford.
    Encinas-Oropesa, A
    Cranfiled University Bedford, UK.
    Ericsson, Torsten
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Materials.
    Stekovic, Svjetlana
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Materials.
    ALLBATROS Advanced Long Life BlAde TuRbine COating Systems2003In: The First International Conference on Gas Turbine Technologies,2003, 2003Conference paper (Refereed)
  • 85. Bech Hanssen, Odd
    et al.
    Wranne, Bengt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Caidahl, Kenneth
    The net pressure gradients after pressure recovery can be predicted by Doppler in aortic bileaflet prostheses.2001In: American Society of Echocardiography,2001, 2001Conference paper (Refereed)
  • 86.
    Benjaminsson, Johan
    Linköping University, Department of Mechanical Engineering.
    Nya renings- och uppgraderingstekniker för biogas2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Biogas is a renewable energy source that is produced by anaerobic digestion of organic mate-rial. In Sweden, biogas predominately comes from sewage water sludge and landfills or from organic waste of households and industries. Small scale digestion plants at farms are espe-cially expected to contribute to increased biogas production in the future. Biogas can be ob-tained directly in it’s raw form and used as fuel in a combustion chamber. However, gas en-gines require biogas purification from hydrogen sulphide and drying from water to avoid cor-rosion. In order to increase the calorific value, carbon dioxide is separated and the Swedish Standard Type A requires the methane content to be 97 % for vehicle gas.

    In the gas treatment process from biogas to vehicle gas, the upgrading step when carbon diox-ide is separated represents the highest cost since conventional upgrading techniques require high investments. This makes the upgrading costs for smaller biogas plants relatively high. In this master thesis, six upgrading methods have been evaluated and four of them are expected to be commercialized within two years. The following upgrading methods are of interest for Sweden:

    - In situ methane enrichment; air desorbs carbon dioxide from the sludge in a

    desorption column. The method is intended for digestion of sewage water sludge and the total upgrading cost is approximately 0,13 kr/kWh by a raw biogas flow 62,5 Nm3/h.

    - Small scale water scrubber; carbon dioxide is absorbed in water under enhanced pressure. The upgrading process is very similar to the conventional water scrub-bing technique and the total upgrading cost is approximately 0,42 kr/kWh by a raw biogas flow of 12 Nm3/h.

    - Cryogenic upgrading; the biogas is chilled to under -85 °C under a pressure of at least 5,2 barg and carbon dioxide can be separated in the liquid phase. The total upgrading cost is approximately 0,12 kr/kWh by a raw biogas flow of 150 Nm3/h. The total upgrading cost can be reduced if the recovered liquid carbon dioxide can be sold.

    - Membrane technique; biogas is upgraded with polymeric membranes that are per-meable for carbon dioxide but not for methane molecules. The method is expected to be adaptable for both smaller and bigger biogas plants and the total upgrading cost is approximately 0,14 kr/kWh by a raw biogas flow of 180 Nm3/h.

    All above mentioned upgrading techniques have methane losses less than two percent and all methods except for the in situ methane enrichment are expected to upgrade biogas to vehicle gas according to the Swedish Standard. In situ methane is expected to upgrade biogas up to 95 % methane content.

    By combustion of unpurified landfill gas in a gas engine, corrosive combustion products and white deposits are formed. Purification of landfill gas can decrease maintenance costs for gas engines. Two landfill gas purification methods have been evaluated and with the first method, contaminants are trapped in ice crystals when the gas is chilled to -25 °C. The second method purifies landfill gas with condensed carbon dioxide.

    An important result of the master thesis is that the in situ methane enrichment has a chance to become an interesting alternative for smaller sewage treatment plants but the method requires additional upgrading to reach 97 % methane content. The most important conclusion is that cryogenic upgrading and membrane technique are expected to satisfy the Swedish Standard. The methods have relatively low upgrading costs and the methane losses are less than two percent. This gives them a good chance to establish in Sweden.

    Download full text (pdf)
    FULLTEXT01
  • 87. Berefelt, F
    et al.
    Boberg, B
    Nygårds, Jonas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Strömbäck, P
    Collaborative GPS/INS Navigation in Urban Environment2004In: ION National Technical Meeting 2003,2004, 2004Conference paper (Other academic)
  • 88.
    Bergdahl, Stefan
    Linköping University, Department of Mechanical Engineering.
    Undersökning av svetsförband med avseende på svetsgeometri, diskontinuiteter och blästring med stålkulor2006Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    Breakdowns of welded structures are usually a consequence of fatigue loading. Fatigue fractures are commonly initiated in the region close to the weld toe but can also initiate from the weld root and from discontinuities inside the weld. The purpose of this investigation was to examine the weld quality of welded joints produced at Volvo Wheel Loaders factory in Arvika. The goal of the investigation is to give a clearer insight regarding factors influencing the fatigue strength of the welded joints and thereby give a better foundation for fatigue strength calculations.

    The investigation is including examination of the weld geometry, weld discontinuities and the effects of shot peening. Mainly three different methods for collecting test data have been used: Plastic replicas cast on the weld profile, weld specimens from a rear frame belonging to a wheel loader of model L110E/120E and Almen testing of the shot peening.

    The results showed that it is not possible to control even transition between the weld material and the base material without after treatment. The most frequent reason why the welded joints did not fulfill the demands in the Volvo Corporate Standard was leg deviation outside the acceptable limit. The most frequent weld defect was lack of fusion inside the weld. The occurrence of this defect was overrepresented in butt welds. The results also showed that the fatigue enhancing effects of shot peening are with today’s process just being used to a minor degree.

    Download full text (pdf)
    FULLTEXT01
  • 89.
    Berggren, Stina
    Linköping University, Department of Mechanical Engineering.
    Analys och modellering av de viskoelastiska effekterna hos polypropenbaserad fiberväv2005Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [sv]

    Företaget BBA Fiberweb tillverkar polypropenbaserad fiberväv som bland annat används inom hygienindustrin till ytskiktet på blöjor, engångskläder, filter, agrikulturapplikationer, fuktspärrar vid husbyggen samt geotextilier.

    Vid tillverkning av fiberväv rullas materialet vid produktion upp på rullar, vilket sker under anbringande av en dragspänning. Spänningen medverkar till att väven packas tätare vilket ger en mindre volym som är positivt ur transportsynpunkt. Dock ger den anbringade spänningen upphov till en spänningsrelaxation i väven samt dimensionsförändringar i materialet. Syftet med examensarbetet är därför att öka förståelsen för hur BBA Fiberwebs fiberväv svarar på en anbringad spänning. Detta har gjorts genom relaxationsstudier samt genom undersökning av tvärkontraktionsbeteendet.

    Vid experimentella studier av spänningsrelaxationsbeteende visas att den anbringade spänningen avtar exponentiellt med tiden. Med hjälp av reologiska modeller har en ekvation tagits fram som beskriver detta beteende.

    En experimentell studie har även utförts för att undersöka materialets dimensions¬förändringar till följd av spänningen. Denna visar att fibervävens ytvikt ökar med ett snittvärde av 3,5 %, efter att spänningen anbringats samt ett snitt placerats i vävens längdled.

    Download full text (pdf)
    FULLTEXT01
  • 90.
    Bergquist, Bjarne
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Statistical approaches to PM steel process improvements1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increased performance:cost ratios for PM steel components is vital if current growth rate of market shares of such components versus competing technology is to be sustained. Both performance and cost of components are affected by variation of component properties. This work focuses on variation; where major variation sources lie and measures to circumvent problems that could be taken.

    A design-of-experiments approach was used to identify the most important green compact variations and interactions of a Fe-P alloy. The results show that the highest impact energies are obtained for high green densities, and without graphite addition. It is concluded that sintered density is the reason for the observed impact energies. Variation sources controlling phosphorus content and added graphite content are of concern since they affect the dimensional stability. Prospects for a robust sintering operation of same alloy is investigated. The objective is to find a setting of the variables investigated to maintain high tensile strength and proof stress without loss of dimensional stability, tensile elongation or impact energy. In the study, an endothermic sintering atmosphere was better for the robustness of the tested properties. A mechanism for the occasionally brittle behavior of the system is concluded to be loss of grain boundary cohesion due to decarburization.

    Possibilities for improved particle size distribution of water atomized powder are studied experimentally and by simulations. The most important variable for all studied responses is water pressure. Higher melt temperatures reduce particle size due to decreased viscosity. Large sulfur additions reduce particle size and this is an effect of reduced surface tension. Narrower size distributions were obtained for powder atomized with aluminum additions and for increased melt temperatures. A model for particle size for water atomization is presented and used in simulations.

  • 91.
    Berntsson, Fredrik
    et al.
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    Eldén, Lars
    Linköping University, Department of Mathematics, Scientific Computing. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Garcia-Padrón, Ricardo
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
    A Comparison of Three Numerical Methods for an Inverse Heat Conduction Problem and an Industrial Application1997Conference paper (Other academic)
  • 92.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Aircraft conceptual design methods2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Generally aircraft conceptual design is defined as the starting point for concept sketcing and evaluation, but before that work can start an even earlier stage has to be covered.

    This is the stage where different scenarios are being worked through in which the aircraft as a platform is supposed to work. The scenarios will differ between civil and military use of course. but will have to fit well inside both customers and manufacturers strategic plans for the future.

    In planning for the future it's vital to think and plan in broader terms, i.e. not only creating single products but rather create families of aircraft. This way of thinking and planning is usual amongst civil manufacturers. Creating a family based product line means better economics, better market coverage and of course lesser risk taking if and when the market changes. On the military side this way of thinking and planning is still quite unusual, mainly because customers are governments which usually only ask for single products.

    The manufacturer from his point of view must think differently, he needs to spread his risk taking, especially as orders from the govemment are becoming scarcer. Therefore a modular product line would be of economic interest and would probably interest more customers.

    The basic idea behind Saab Gripen (three roles merged into one single platform), or the US Joint Strike Fighter (JSF) idea of a modular aircraft, could be seen as the start of some kind of new family planning, but family planning on the military side could reach further than that. Probably military manufacturers can learn a lot from their civil counterparts.

    Conceptual design might be a one man job in the early stages, but will very soon develop into team work. This development is only natural since the conceptual designer can't be expected to have detailed knowledge or experience which will cover every item. Conceptual design introduces a holistic viewpoint into the aircraft design process and it's vital to keep this viewpoint as long as possible. This becomes even more important over time, since the more detailed the project gets, the overall goal tends to drown into details.

    Conceptual design phase offers the only occasion when design changes still can be made quite easily. Design freeze is not only a simple freeze of aircraft layout and geometry, it also sets the fmal prize tag on the aircraft. So in a way it is what you did (and what you forgot to do) in the conceptual design phase which fmally decides the faith of the end product. Hence conceptual design needs all the time it takes to be able to develop successful future products.

    Generally there are two sides to conceptual design: either you develop a brand new design or make changes to an already existing one. Either way has its own needs and can't be run in the same manner, since different tools are needed in both cases. A new design needs a good conceptual design program, while in the latter case only minor parts of it might be used. A new design starts off fresh; everything is possible and nothing is sacred, but changing on an existing design means working with hands tied, you do not change things that easily.

    Aircraft Conceptual Design takes long time to learn. It requires more than just being able to run a conceptual design program. Previous experience in a number of different aircraft design disciplines is a must; so is the ability to be able to humbly listen to experienced people's knowledge and advice.

    This paper describes methods for aircraft conceptual design at two basic levels. At the top level there's a method described for conceptual design of civil jet transport aircraft.

    On the second level different methods for conceptual design of core aircraft systems such as landing gear, environmental control and hydraulic are presented.

    List of papers
    1. The Sunriser - A Design Study in Solar Powered Flight
    Open this publication in new window or tab >>The Sunriser - A Design Study in Solar Powered Flight
    2000 (English)In: SAE Technical Paper 2000-01-5507, 2000Conference paper, Published paper (Other academic)
    Abstract [en]

    The design task for last year students in Aircraft Design at Linköping University was to design a manned solar-powered aircraft. The mission was to survey the U.S./Mexican borderline in search for possible intruders. The Sunriser began as a sole paper project, but quite soon we felt a need to prove that solar-powered flight really was feasible. Thus the decision was made to design and build a solar powered demonstrator of our own design.

    The demonstrator aircraft, a radio controlled model aircraft named "the Sunrazor," was designed, built and flown with good result.

    This paper deals with the basic theory of sun-powered flight and describes the basic thoughts and design considerations which finally led to the configurations chosen.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-35265 (URN)10.4271/2000-01-5507 (DOI)26023 (Local ID)26023 (Archive number)26023 (OAI)
    Conference
    2000 World aviation Congress, San Diego, California, October, 2000
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-11-07
    2. Landing Gear Design in the Conceptual Design Phase
    Open this publication in new window or tab >>Landing Gear Design in the Conceptual Design Phase
    1999 (English)In: SAE Technical Paper 1999-01-5523, 1999Conference paper, Published paper (Other academic)
    Abstract [en]

    A well-designed landing gear and a proper integration is of utmost importance for the success of any aircraft design. This should never be neglected but often is, especially in the conceptual design stage. This paper reflects the author''s own experience in landing gear design of the Saab Gripen aircraft as well as experience gained on aircraft conceptual designs of later dates. The aim of the paper is to underline the importance of spending more time on landing gear design and integration in conceptual design. The paper reflects the importance of proper interaction between landing gear design and other disciplines and above all underlines the fact that landing gear design should be treated as an equally important design parameter, just as any other, in the final choice of aircraft configuration.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-100442 (URN)10.4271/1999-01-5523 (DOI)
    Conference
    1999 World aviation Congress, San Fransisco, California, October, 1999
    Available from: 2013-11-07 Created: 2013-11-07 Last updated: 2013-11-07
    3. Sizing the Landing Gear in the Conceptual Design Phase
    Open this publication in new window or tab >>Sizing the Landing Gear in the Conceptual Design Phase
    2000 (English)In: SAE Technical Paper 2000-01-5601, 2000Conference paper, Published paper (Other academic)
    Abstract [en]

       

    A tool has been developed in order to design or evaluate a proposed landing gear layout and to determine its size and weight. The methodology has been developed primarily for landing gears of the telescopic suspension type.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-35273 (URN)10.4271/2000-01-5601 (DOI)26049 (Local ID)26049 (Archive number)26049 (OAI)
    Conference
    2000 World aviation Congress, San Diego, California, October, 2000
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-11-07
    4. Conceptual Design of a New Generation JAS 39 Gripen Aircraft
    Open this publication in new window or tab >>Conceptual Design of a New Generation JAS 39 Gripen Aircraft
    2006 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes the conceptual phase of a modification proposal for Saab Gripen, which aims to create the best possible basis for future aircraft development. One of the main tasks in this respect is to investigate different means to extend range. This paper describes the technical outcome from the concept generation, concept selection, and concept refinement at system and airframe level. The chosen concept involves relocation and redesign of the main landing gear. The original main landing gear bay is converted into fuel tanks. The relocation of the main gear enables a new ventral twin store carriage with supersonic jettison capability to be introduced. The concept proposal yields the following improvements:

    · Increased range due to increased fuel capability

    · Increased maximum allowed takeoff weight due to beefe d-up main gear

    · Increased weapon flexibility and capability due to introduction of two new ventral store

    · Introducing supersonic jettison capability

    The paper also includes a description of how the work is related to the overall design process in general and the conceptual phase in particular, as described in design methodology literature.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12980 (URN)10.2514/6.2006-31 (DOI)
    Conference
    44th AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2013-11-07
  • 93.
    Berry, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Aircraft Desígn at LiU2004In: EWADE 2004,2004, 2004Conference paper (Other academic)
  • 94.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Landing Gear Design in the Conceptual Design Phase1999In: SAE Technical Paper 1999-01-5523, 1999Conference paper (Other academic)
    Abstract [en]

    A well-designed landing gear and a proper integration is of utmost importance for the success of any aircraft design. This should never be neglected but often is, especially in the conceptual design stage. This paper reflects the author''s own experience in landing gear design of the Saab Gripen aircraft as well as experience gained on aircraft conceptual designs of later dates. The aim of the paper is to underline the importance of spending more time on landing gear design and integration in conceptual design. The paper reflects the importance of proper interaction between landing gear design and other disciplines and above all underlines the fact that landing gear design should be treated as an equally important design parameter, just as any other, in the final choice of aircraft configuration.

  • 95.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Sizing the Landing Gear in the Conceptual Design Phase2000In: SAE Technical Paper 2000-01-5601, 2000Conference paper (Other academic)
    Abstract [en]

       

    A tool has been developed in order to design or evaluate a proposed landing gear layout and to determine its size and weight. The methodology has been developed primarily for landing gears of the telescopic suspension type.

  • 96.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    The Sunriser - A Design Study in Solar Powered Flight2000In: SAE Technical Paper 2000-01-5507, 2000Conference paper (Other academic)
    Abstract [en]

    The design task for last year students in Aircraft Design at Linköping University was to design a manned solar-powered aircraft. The mission was to survey the U.S./Mexican borderline in search for possible intruders. The Sunriser began as a sole paper project, but quite soon we felt a need to prove that solar-powered flight really was feasible. Thus the decision was made to design and build a solar powered demonstrator of our own design.

    The demonstrator aircraft, a radio controlled model aircraft named "the Sunrazor," was designed, built and flown with good result.

    This paper deals with the basic theory of sun-powered flight and describes the basic thoughts and design considerations which finally led to the configurations chosen.

  • 97.
    Bjurstam, Peter
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology. Univ.,.
    Skärkrafter vid fräsning: teori och verklighet1994Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This thesis deals with the machining method milling and the forces affecting the tool during a milling operation. A survey of different tool geometries and conditions of the tool engagement during a machining process is presented. The general cutting theory and the equations used to estimate the load are explored. For practical use this simplified approach may be enough but when a more precise calculation of the load condition are required, i.e for process control or research when the varying chip thickness must be taken into consideration, the general theory is not adequate.

    As a result of the research work an accurate mathematical model and a computer software has been developed at the Division of Production Engineering. The model calculates the cutting forces acting on the tool during one revolution. The stepsize is one degree. The forces are expressed according to a coordinate system with its origin in the center of the tool. In order to evaluate the software the calculated values have been compared with real forces recorded during machining. The reliability of the equipment and of the developed model has been verified.

    Different ways for further development of the software have also been investigated. These developments are based on tool life studies made at the Division. One of the applications presented in the thesis is related to the working material. Equations for calculation of the material parameters needed are developed and the structure for a new computer software for the calculations is shown. The presented results can simplify the development of adaptive control modules and improve process planning routines associated with numerical programming of machine tools.

  • 98.
    Bjurstam, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Production Engineering.
    Software Routines for Milling Operations2001In: Konf. PEDAC 2001 Alexiandria,2001, 2001Conference paper (Other academic)
  • 99.
    Bjurstam, Peter
    Linköping University, Department of Mechanical Engineering, Production Engineering.
    Software Routines for Milling Operations2000In: PEDAC 2001,2000, 2000Conference paper (Other academic)
  • 100.
    Bjurstam, Peter
    et al.
    Linköping University, Department of Mechanical Engineering, Production Engineering.
    Björklund, Stefan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Production Engineering.
    Novak, Arne
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Production Engineering.
    Determination of Maerial Parameters for Cutting Data Calculations in Milling2001In: Conference on Production Research, ICPR-16,2001, 2001Conference paper (Other academic)
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