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Topology optimization of vehicle body structures: method, theory and applications
Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This dissertation is concerned with topology optimization of vehicle body structures.

The first part of this thesis gives a summary of the research project. A design process for complex mechanical structures is presented. This design process includes an optimization step where simplified models are optimized. These simplified models are frame structures consisting of beams and joints. Joints are modelled as a collection of sub-elements to support for a topological change during optimization. Parameterization of beams and joint is also presented and design variables are introduced.

An application of this frame topology optimization method, concerning a vehicle body structure, is presented.

Two extensions to the theory are also presented. First, the possibility to penalize joints to support for easily realizable results is presented. This is followed by a two-material interpolation that introduces the possibility of using a mixed material structure.

This introductory part is followed by five appended papers produced within the framework of this research.

Abstract [sv]

Denna doktorsavhandling behandlar topologioptimering av fordonskarosser.

Första delen i avhandlingen ger en summering av forskningsprojektet. En produktutvecklingsprocess för komplexa mekaniska system presenteras. Denna process innefattar ett optimeringssteg där förenklade modeller optimeras. Dessa förenklade modeller är modellerade som ramstrukturer baserade på balkar och knutar. Knutarna är modellerade m.h.a. en uppsättning delelement för att möjliggöra en topologisk ändring under optimimeringsprocessen. Även balkars och knutars parameterisering och designvariabler beskrivs i den inledande delen. En tillämpning av topologioptimering får ramar presenteras på en fordonskarossmodell. Två utvecklingar av teorin gås också igenom. Först beskrivs möjligheten att tillämpa knutstraff vilket möjliggör skapandet av mer realiserbara modeller. Detta efterföljs av en tvåmaterialinterpolering vilken introducerar möjligheten att generera strukturer med optimalt materialval. Slutligen identifieras framtida forskning inom området.

Den inledande delen följs sedan av fem artiklar vilka har genererats under projektets gång.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2004. , 43 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 885
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-22915Local ID: 2270ISBN: 91-7373-979-0 (print)OAI: oai:DiVA.org:liu-22915DiVA: diva2:243228
Public defence
2004-09-09, Sal C3, Hus C, Linköping Universitet, Linköping, 10:15 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-01-23
List of papers
1. A design process for complex mechanical structures using property based models, with application to car bodies
Open this publication in new window or tab >>A design process for complex mechanical structures using property based models, with application to car bodies
2002 (English)In: Proceedings of the 7th International Design Conference: DESIGN 2002 / [ed] D. Marjanovic, 2002, 611-620 p.Conference paper, Published paper (Refereed)
Abstract [en]

The design of complex mechanical structures is multi-objective and includes the treatements of a wide range of requirements such as quantitative, qualitative, subjective and objective. An example of this type of structure is a car body, where design has a long tradition from wich valuable experience can be drawn however fixation to old practises has to be avoided. The design process described in the paper aims to reduce lead time while not excluding innovative solutions. By representing all concepts on a common base as a property based model and use optimisation, an objective analysis can be done early thereby only viable concepts will emerge to further selection. The data gained at early phases is used as input to detail design reducing iterations.

Keyword
Design method, concept selection, optimisation, structural design, mechanical structures, multi-objective
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-87817 (URN)
Conference
DESIGN2002 Conference, 14-17 May, Cavtat, Croatia 2002
Available from: 2013-01-23 Created: 2013-01-23 Last updated: 2013-01-23
2. Structural topology optimisation: an application review
Open this publication in new window or tab >>Structural topology optimisation: an application review
2005 (English)In: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 37, no 1, 67-80 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents a survey of the literature on the use of structural topology optimisation in the vehicle industry. The focus is on some specific applications rather than on any specific optimisation discipline. The survey starts with a general historic resume and continues with a more detailed description of the status today. New applications and areas for optimisation are presented, with short summaries of the referred papers. The major focus is on applications for vehicle body structures. Trends and potential areas of research are also explored.

Place, publisher, year, edition, pages
InderScience Publishers, 2005
Keyword
structural topology optimisation; vehicle applications; vehicle industry
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-87819 (URN)10.1504/IJVD.2005.006089 (DOI)000227723100004 ()
Available from: 2013-01-23 Created: 2013-01-23 Last updated: 2017-12-06
3. Topology optimization of frame structures with flexible joints
Open this publication in new window or tab >>Topology optimization of frame structures with flexible joints
2003 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 25, no 3, 199-214 p.Article in journal (Refereed) Published
Abstract [en]

A method for structural topology optimization of frame structures with flexible joints is presented. A typical frame structure is a set of beams and joints assembled to carry an applied load. The problem considered in this paper is to find the stiffest frame for a given mass. By introducing design variables for beams and joints, a mass distribution for optimal structural stiffness can be found. Each beam can have several design variables connected to its cross section. One of these is an area-type design variable which is used to represent the global size of the beam. The other design variables are of length ratio type, controlling the cross section of the beam. Joints are flexible elements connecting the beams in the structure. Each joint has stiffness properties and a mass. A framework for modelling these stiffnesses is presented and design variables for joints are introduced. We prove a theorem which can be interpreted as the fact that the removal of structural elements, e.g. joints or beams, can be modelled by a small strictly positive material amount assigned to the element. This is needed for the computations of sensitivities used in the applied gradient based iterative method. Both two and three dimensional problems, as well as multiple load cases and multiple mass constraints, are treated.

Keyword
Flexible joints, Frame structures, Joint modelling, Topology optimization
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46540 (URN)10.1007/s00158-003-0281-z (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
4. Topology optimization of frame structures: a vehicle body application
Open this publication in new window or tab >>Topology optimization of frame structures: a vehicle body application
(English)Manuscript (preprint) (Other academic)
Abstract [en]

An application of frame topology optimization on a vehicle body structure is presented. A traditional way of describing the elements of a vehicle body structure is by beams and joints. Based on this, the models used in this study are frame structures with flexible joints. The problem considered is to find that stiffest frame design which fulfills a weight requirement. To support for a topological change of joints, each joint is modelled as a set of subelements. A set of design variables are applied to each beam and joint subelement. Two kinds of design variables are used. One of these variables is an area-type design variable used for controlling the global element size and supporting a topology change. The other variables are length ratio variables controlling thecross-section of bemas and internal stiffness properties of joints. The vehicle body application presented in this paper shows the usefulness of topology optimization in the early design phase.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-87820 (URN)
Available from: 2013-01-23 Created: 2013-01-23 Last updated: 2013-01-23
5. Topology optimization of frame structures: joint penalty and material selection
Open this publication in new window or tab >>Topology optimization of frame structures: joint penalty and material selection
2005 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 30, no 3, 193-200 p.Article in journal (Refereed) Published
Abstract [en]

This paper deals with joint penalization and material selection in frame topology optimization. The models used in this study are frame structures with flexible joints. The problem considered is to find the frame design which fulfills a stiffness requirement at the lowest structural weight. To support topological change of joints, each joint is modelled as a set of subelements. A set of design variables are applied to each beam and joint subelement. Two kinds of design variables are used. One of these variables is an area-type design variable used to control the global element size and support a topology change. The other variables are length ratio variables controlling the cross section of beams and internal stiffness properties of the joints. This paper presents two extensions to classical frame topology optimization. Firstly, penalization of structural joints is presented. This introduces the possibility of finding a topology with less complexity in terms of the number of beam connections. Secondly, a material interpolation scheme is introduced to support mixed material design.

Place, publisher, year, edition, pages
Springer, 2005
Keyword
topology optimization; frame structure; joint penalty; material selection
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-87821 (URN)10.1007/s00158-005-0515-3 (DOI)000234195100003 ()
Available from: 2013-01-23 Created: 2013-01-23 Last updated: 2017-12-06

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