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Topology optimization of vehicle structures
Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology.
2004 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns topology optimization of vehicle structures. Vehicle structures are considered to be composed of beams joined together and the work has been focused on a method for beam topology optimization including joints.

The method presented has been implemented in Matlab and simple examples as well as more realistic applications have been studied. The research work is presented in four papers.

Paper I presents beam topology opt imization with flexible joints. Design variables on beam cross sectional geometries and joint properties are introduced. A generic joint element is formulated in order to do topology optimization and the compliance topology optimization problem is described and solved.

Paper II is an extension of Paper I where the joints are more general with stiffness properties in different directions. The paper introduces also a way to find joint stiffness for the generic joints.

Paper III is a short application paper where a bus structure is optimized using the method presented in Paper l and II.

Paper IV, finally, presents an approach to optimize a frame structure with regard to cost as well as for compliance and mass as in previous papers. This multi-attribute optimization method is applied to a ten beam structure and to a larger application example.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2004. , 6 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1088
Series
Linköping studies in science and technology. Thesis, 148
Keyword [en]
topology optimization, frame structure, vehicle structure, flexible joint
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-22919Local ID: 2274ISBN: 91-7373-942-1 (print)OAI: oai:DiVA.org:liu-22919DiVA: diva2:243232
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-11-12
List of papers
1. 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
2. Frame structure topology optimization with extended flexible joints
Open this publication in new window or tab >>Frame structure topology optimization with extended flexible joints
(English)Manuscript (preprint) (Other academic)
Abstract [en]

This paper describes a joint formulation for beam copology optimization with flexible joints. Joints are important structural elements for stiffness and by including them in the topology optimizing problem joints will get the right stiffness. The joints are modelled by an assembly of more generic 2-joints, which have the ability to have different stiffness in different directions. This will lead to that unnecessary stiffness components are found and simpler joints may be constructed. The paper also describes a way to find stiffness values for the 2-joints and some examples will show the functionality of the joints.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-100816 (URN)
Available from: 2013-11-12 Created: 2013-11-12 Last updated: 2013-11-12
3. Topology optimization of vehicle structures
Open this publication in new window or tab >>Topology optimization of vehicle structures
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A method for structural topology optimization of beams with flexible joints is presented. For vehicle structures the result of topology optimization is often resulting in a frame structure consisting of beams and joints connecting the beams. The problem at hand is to find the topology, i.e. how beams and joints are connected, in the best way and as lightweight as possible for the requirements on the st ructure. For vehicles the properties of the joints are important for the total stiffness response and for the construction of the joints. An application problem of a low floor city bus is presented and the result of the optimization is discussed. By using topology optimization a good structural concept is found for further analysis and construction.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-100817 (URN)
Available from: 2013-11-12 Created: 2013-11-12 Last updated: 2013-11-12
4. Multi-attribute topology optimization of frame vehicle structures
Open this publication in new window or tab >>Multi-attribute topology optimization of frame vehicle structures
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Topology optimization of beam structures is considered in this paper where we also introduce cost as a state in addition to the structural properties such as weight and compliance. Cost for beams is here assumed to be composed by material cost and detail cost. An example structure is thoroughly evaluated in order to examine the total design space of topologies for the structure. A method to find a less costly structure is discussed and an application example is shown.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-100819 (URN)
Available from: 2013-11-12 Created: 2013-11-12 Last updated: 2013-11-12

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