Open this publication in new window or tab >>2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]
Multidisciplinary design optimization (MDO) can be used in computer aided engineering (CAE) to efficiently improve and balance performance of automotive structures. However, large-scale MDO is not yet generally integrated within automotive product development due to several challenges, of which excessive computing times is the most important one. In this thesis, a metamodel-based MDO process that fits normal company organizations and CAE-based development processes is presented. The introduction of global metamodels offers means to increase computational efficiency and distribute work without implementing complicated multi-level MDO methods.
The presented MDO process is proven to be efficient for thickness optimization studies with the objective to minimize mass. It can also be used for spot weld optimization if the models are prepared correctly. A comparison of different methods reveals that topology optimization, which requires less model preparation and computational effort, is an alternative if load cases involving simulations of linear systems are judged to be of major importance.
A technical challenge when performing metamodel-based design optimization is lack of accuracy for metamodels representing complex responses including discontinuities, which are common in for example crashworthiness applications. The decision boundary from a support vector machine (SVM) can be used to identify the border between different types of deformation behaviour. In this thesis, this information is used to improve the accuracy of feedforward neural network metamodels. Three different approaches are tested; to split the design space and fit separate metamodels for the different regions, to add estimated guiding samples to the fitting set along the boundary before a global metamodel is fitted, and to use a special SVM-based sequential sampling method. Substantial improvements in accuracy are observed, and it is found that implementing SVM-based sequential sampling and estimated guiding samples can result in successful optimization studies for cases where more conventional methods fail.
Place, publisher, year, edition, pages
Linköping, Sweden: Linköping University Electronic Press, 2017. p. 48
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1870
Keywords
multidisciplinary design optimization (MDO), metamodel, artificial neural network (ANN), support vector machine (SVM), sequential sampling, crashworthiness, automotive structure, spot weld optimization
National Category
Mechanical Engineering Applied Mechanics Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-140875 (URN)10.3384/diss.diva-140875 (DOI)9789176854822 (ISBN)
Public defence
2017-10-03, C3, Hus C, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Funder
Vinnova, 2009-00314Vinnova, 2014-01340
2017-09-142017-09-142019-10-11Bibliographically approved