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Supporting concept synthesis by use of genetic algorithms
Linköping University, Department of Mechanical Engineering, Machine Design. Linköping University, The Institute of Technology.
Linköping University, Department of Mechanical Engineering, Machine Design. Linköping University, The Institute of Technology.
2004 (English)In: Tools and Methods of Competitive Engineering, Proceedings Fifth International Symposium on Tools and Methods of Competitive Engineering / [ed] Horvath, I; Xirouchakis, P, Rotterdam: Milpress , 2004, 255-266 p.Conference paper, Published paper (Other academic)
Abstract [en]

Evolutionary algorithms are common in parameter optimisation of a given solution. Conceptual design, however, initially involves finding a principle solution, and a bad principle choice can hardly be compensated by even the best detail design and parameter optimisation. This article therefore describes an approach to apply agenetic algorithm for concept synthesis by modelling principle choices as weil as their parameter values and treating both asoptimisation variables. The results are three alternative genome representations (of which a tree genome finally was chosen), algorithms for crossover and mutation operating on the tree genome and an evaluation strategy including weighted sum assessment over multiple criteria (conjunctive selection) as weil as meclhanisms that favour (disjunctive selection) or penalise (disjunctive elimination) concepts performing well or bad in one criterion respectively. The first task was to develop the method, which is also the focus of this article. Testing it in case studies in order to assess the effectiveness and practical applicability remains as a subsequent task. It can though be concluded that the presented approach fulfils its purpose, as it is capable of modelling the choice of the right principle solution during conceptual design.

Place, publisher, year, edition, pages
Rotterdam: Milpress , 2004. 255-266 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-21078ISBN: 90-5966-018-8 (print)OAI: oai:DiVA.org:liu-21078DiVA: diva2:240516
Conference
Fifth International Symposium on Tools and Methods of Competitive Engineering, Lausanne, Switzerland, April 13 - 17, 2004
Available from: 2009-09-28 Created: 2009-09-28 Last updated: 2012-11-30Bibliographically approved
In thesis
1. On Evaluation of Design Concepts: Modelling Approaches for Enhancing the Understanding of Design Solutions
Open this publication in new window or tab >>On Evaluation of Design Concepts: Modelling Approaches for Enhancing the Understanding of Design Solutions
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This dissertation embraces the issue of evaluating design concepts. Being able to sort out the potential“best solutions” from a set of solutions is a central and important part of the design process. The subjectdiscussed in this dissertation has its origins in the lack of knowledge about design concepts, somethingwhich is characteristic of the initial part of the design process and which frequently causes problems whenit comes to evaluation and selection of solutions. The purpose of this dissertation is to develop aids andmethods that enhance the understanding of design concepts in the early phases of the design process.

From deductive reasoning about the fundamental mechanisms of the evaluation activity, the work hasbeen divided into three different areas: process and system modelling, concept optimisation, andidentification of potential failures.

The bearing of the work within the area of process and system modelling has a verifying character. Theobjective of the work has been to analyse how established design methodology, which has its commonapplications within traditional engineering industry, may be applied within an area that is characterised bymore multidisciplinary interfaces, like biotechnology. The result of a number of case studies, in whichdifferent types of biotechnical systems where analysed and modelled, shows that the methodology isapplicable even for biotechnical products. During the work the methodology has also been furtherelaborated on in order to better suit the distinguishing characteristics exhibited in the development ofbiotechnical systems.

Within the area of concept optimisation, an approach for optimising the concept generation has beenelaborated. By formalising the step in both concept generation and evaluation, it has been possible toapply genetic algorithms in order to optimise the process. The work has resulted in a model thatautomatically creates and sorts out a number of potential solutions from a defined solution space and adefined set of goals.

The last area, which deals with identification of potential failures, has resulted in a rather novel way toconsider and model the behaviour of a system. The approach is an elaboration of the modellingtechniques within system theory, and deduces the system’s behaviour from known physical phenomenaand the system’s ability to effectuate them. The way the different behaviours interact with one another, byaffecting the properties of the system, determines the potential for a failure to occur. A “failure”,according to the model, is described as an unintended behaviour which obstructs the system’sfunctionality, i.e. which affects the conditions of a desired behaviour.

The dissertation has resulted in three different means for approaching the difficulties associated with theevaluation of design concepts. The means are applicable during different parts of the design process, butthey all address the same issue, viz. to enhance the understanding of the design solutions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 80 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1273
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-21085 (URN)978-91-7393-536-4 (ISBN)
Public defence
2009-10-23, C3, C-huset, Campus Valla, Linköpings universitet, Linköping, 13:15 (English)
Opponent
Supervisors
Available from: 2009-09-28 Created: 2009-09-28 Last updated: 2009-09-28Bibliographically approved
2. Constraint-based conceptual design using principle solution elements
Open this publication in new window or tab >>Constraint-based conceptual design using principle solution elements
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The design of new products is an important engineering activity, and much of the competitiveness in high-salary countries depends on the ability to develop innovative products with acceptable time to market.

During conceptual design, the principle solution for a product is conceived. This early phase of a systematic design process is of great importance for the later success of products. Available design support tools are mainly oriented towards the later phase of embodiment design (e.g. volume modellers), and they do not effectively support conceptual design. This work presents an information model, methods, and a tool for computer-supported conceptual design.

During conceptual design, creative steps and the modelling of function structures, hierarchies, solution principles and concepts must be supported in order to reduce the considerable time needed by systematic design methods.

Literature as well as existing research prototypes have been analysed to determine the state of the art in research regarding computer-supported conceptual design. Design projects of master's degree engineering students, previously carried-out at the division, have been studied in order to gain insight into the needs and possibilities of supporting concept generation for various design tasks.

The work has resulted in a parametric, feature-based information model that is able to describe concepts as choices of principle solution elements and their quantification by value assignments. The model operates on a higher semantic level than for example document or model files by applying a constraint network that connects parameters of requirements, function structure, F/M tree, solution principles and concepts. The model has been tailored towards easy exchangeability of principle solution elements by a division into different constraint types, of which internal constraints are directly reusable. Using the model, the co-evolution of concept synthesisand early calculations is facilitated.

The presented information model has been implemented in a prototype of an interactive tool for computer-supported conceptual design. The tool includes a graphical user interface for work with views for function structures and F/M trees. Reuse is enabled by storing and re-inserting principle solution elements from a database.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, Department of Mechanical Engineering, 2005. 197 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 930
Keyword
Conceptual design, functional modelling, constraint-based design, design reuse, VDI 2222, product modelling, design support
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-24463 (URN)6576 (Local ID)91-85297-59-3 (ISBN)6576 (Archive number)6576 (OAI)
Public defence
2005-04-22, C3, Hus C, Campus Valla, Linköping, 10:15 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2012-11-30

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Wilhelms, SörenDerelöv, Micael

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