Models, methods and tools for car body development

Abstract: The research presented in this licentiate thesis has been carried out at the advanced body engineering group at Volvo Car Corporation (VCC). The research has been done while enrolled at the Division of Computer Aided Design (CAD) at Luleå University of Technology. The research was initiated by VCC as part of the VCC industrial PhD program and in close co-operation with the CAD division at Luleå University of Technology. The research has been conducted within the ENDREA national graduate program. This licentiate thesis deals with the development of complex mechanical structures, from concept to detail design, as applied to car bodies. The role of concepts has been examined and a standardised language based on three organ types (beams, joints and panels) has been made to break down and quantify concept performance. Concept selection has been addressed with care, not to impose an off-the-shelf method, but to identify the needs of the particular situation [Paper A, Bylund, Fredricson and Thompson 02]. Efforts have been made to clarify how computer tools and analysis methods are used in product development in industry today. It has been found that the design and the analysis activities are separated. In order to speed up the development, a concurrent engineering approach is needed. This calls for integration of computer support and analysis in the development process. Based on the above findings, a new development process for car bodies has been developed, reaching from concept to detail design. A Property Based Model (PBM), [Paper B, Bylund and Eriksson 01], is built up for each concept, and represents the mechanical and spatial properties of the body concept. The PBM is constructed from organs, [Hubka, Andreasen and Eder 88], which represent requirements at a local level. The chosen organs for the car body are beams, joints and panels, [Paper B, Bylund and Eriksson]. An optimisation procedure is used to normalise the alternative concept PBM models with respect to key global requirements, e.g. global stiffness, weight, crash worthiness, etc. The normalisation assures that all concepts are on the same level of maturity. For example, a new innovative concept should not just show a fraction of its performance while an old well-known technology results in a concept close to its maximum performance. The results of the procedure are used as the basis for evaluation of the concepts. An analysis tool, ADRIAN, has been developed, tailor-made according to the broken down concept performance, and necessary in the presented process. The main feature of the tool is the possibility to transfer part of the analysis from simulation experts to design engineers, thereby increasing the simulation usage in product development. The first tests of ADRIAN in an industrial environment showed that technical issues such as analysis stability and speed are satisfied, and that the target group, the design engineers without experience of analysis, found it easy and valuable to use, which is equally important. The overall purpose is to arrive at a simulation- driven design based on requirements broken down to local level rather than a simulation-verified design. Four papers, A-D, have been included in this licentiate thesis. The first paper, "A design process for complex mechanical structures using Property Based Models, with application to car bodies", is the backbone of this thesis and describes the design process developed. The second paper, "Simulation Driven Car Body Development Using Property Based Models", describes the concept of Property Based Models (PBM) more in depth, with some examples. The third paper, "A Study of the effects of different system architectures on the development process", is of a theoretical nature and address the role of different product architectures in design. Finally the fourth paper, "ADRIAN a program for evaluating the stiffness of joints and its application in the development process", describes ADRIAN, one of the programs, for enhancing the design process proposed in the first two papers. Appended Papers Paper A BYLUND, N., FREDRICSON, H. AND THOMPSON, G.: A design process for complex mechanical structures using Property Based Models, with application to car bodies. In the proceedings to Design 2002 Conference, 14-17 of May 2002, Dubrovnik, Croatia. Paper B BYLUND, N. AND ERIKSSON, M.: Simulation Driven Car Body Development Using Property Based Models SAE paper 2001-01-3046, in proceedings to IBEC 2001. (Conference postponed to 8-12 July 2002) Paper C GRANTE, C. AND BYLUND, N.: A Study of the Effects of Different System Architectures on the Development Process. In the proceedings to Design 2002 Conference, 14-17 of May 2002, Dubrovnik, Croatia. Paper D BYLUND, N., SANDSTRÖM, H. AND SHAMLO, M.: ADRIAN: a program for evaluating the stiffness of joints and its application in the development process.