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Structural optimization of product families subjected to multiple crash load cases
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
2010 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 41, no 5, 797-815 p.Article in journal (Refereed) Published
Abstract [en]

This paper discusses the problem of structural optimization of product families subjected to multiple load cases, evaluated by computationally costly finite element analysis. Product families generally have a complex composition of shared components that makes individual product optimization difficult as the relation between the shared variables is not always intuitive. More optimal is to treat the problem as a product family optimization problem. Though, for product families subjected to multiple and computationally costly crash loads, the optimization problem takes too long time to solve with traditional methods. Therefore, a new optimization algorithm is presented that decomposes the family problem into sub-problems and iteratively reduces the number of sub-problems, decouple and solve them. The algorithm is applicable for module based product families with predefined composition of generalized commonality, subjected to multiple load cases that can be analyzed separately. The problem reduction is performed by only considering the constraints that are critical in the optimal solution. Therefore the optimization algorithm is called the Critical Constraint Method, CCM. Finally the CCM algorithm is evaluated by two product family optimization problems.

Place, publisher, year, edition, pages
Springer Science Business Media , 2010. Vol. 41, no 5, 797-815 p.
Keyword [en]
Product family optimization, Multiple crash loads, Nonlinear systems, Response surface methodology, Meta model approximations, Critical constraints
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-54846DOI: 10.1007/s00158-009-0471-4ISI: 000276075900011OAI: oai:DiVA.org:liu-54846DiVA: diva2:310871
Available from: 2010-04-16 Created: 2010-04-16 Last updated: 2011-09-19Bibliographically approved
In thesis
1. Optimization and robustness of structural product families
Open this publication in new window or tab >>Optimization and robustness of structural product families
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns structural optimization of product families and robustness. The overall objective is to find a method for performing structural optimization of product families subjected to multiple crash load cases and to ensure a robust behavior.

A product family is a family of products where every product variant, or family member, shares at least one component with at least one other product in the family. Structural optimization of such a family is complex and for expensive function evaluations, e.g. crash simulations, the computing time to solve the problem with traditional methods gets unrealistically long. Therefore, a new optimization algorithm for product families is presented, called the critical constraint method (CCM), that reduces the number of required evaluations by only considering the active constraints in the optimal solution.

Traditionally optimized structures have a tendency of being sensitive to small variations in the design or loading conditions. As these kind of variations are inevitable, it is important to account for this sensitivity in the design process to ensure the robustness of the optimized design.

The thesis is divided in two parts. The first part serves as a theoretical background to the second part, the two appended articles. This first part includes introductions to the concepts of product families, optimization, meta modeling and robust design.

The first appended paper presents a new optimization algorithm for product families subjected to multiple crash loads. The method is compared to traditional methods and tested on two smaller product family examples.

The second paper is an application of an existing sensitivity analysis method on a large industrial application example. A sensitivity analysis is performed on a Scania truck cab subjected to an impact load in order to identify the most  influencing variables on the crash responses.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 50 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1403
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-17947 (URN)LIU-TEK-LIC-2009:11 (Local ID)978-91-7393-626-2 (ISBN)LIU-TEK-LIC-2009:11 (Archive number)LIU-TEK-LIC-2009:11 (OAI)
Presentation
2009-06-10, A-huset, Campus Valla, Linköpings universitet, Linköping, 10:00 (English)
Opponent
Supervisors
Available from: 2009-10-16 Created: 2009-04-27 Last updated: 2013-10-24Bibliographically approved
2. Optimization and Robustness of Structural Product Families
Open this publication in new window or tab >>Optimization and Robustness of Structural Product Families
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns structural optimization and robustness evaluations, and new methods are presented that considerably reduce the computational cost of these evaluations.

Optimization is an effective tool in the design process and the interest from industry of its usage is quickly increasing. However, the usage would probably have grown faster if the required number of computationally costly finite element analyses could be reduced. Especially in the case of product family optimization, the problem size can easily get too large to be solved within a reasonable time. This is sometimes also true for robustness evaluations. To enable the usage of optimization and robustness evaluations also for large scale industrial problems, two new methods are here presented, which require a considerably smaller number of finite element analyses.

The first method concerns structural optimization of product families subjected to multiple crash load cases. Here, the number of required finite element analyses are considerably reduced by only considering the critical constraint in each iteration step.

The second method is an approach to approximate the variable sensibility based on the distribution of internal energy in a structure. The method can be used to evaluate the relative robustness of different design proposals or for structural optimization. Since the method is independent of the number of parameters and design variables the computational cost of such evaluations is drastically reduced for computationally large problems.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. 50 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1397
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-70372 (URN)978-91-7393-072-7 (ISBN)
Public defence
2011-10-18, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2011-09-05 Created: 2011-09-05 Last updated: 2011-09-19Bibliographically approved

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Öman, MichaelNilsson, Larsgunnar

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