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Vehicle structure crashworthiness design is one of the most challenging problems in product development and it has been studied for decades. Challenges still remain, which include developing a reliable and systematic approach for general crashworthiness design problems, which can be used to design an optimum vehicle structure in terms of topology, shape, and size, and for both structural layout and material layout. In this paper, an advanced and systematic approach is presented, which is called Magic Cube (MQ) approach for crashworthiness design. The proposed MQ approach consists of three major dimensions: Decomposition, Design Methodology, and General Considerations. The Decomposition dimension is related to the major approaches developed for the crashworthiness design problem, which has three layers: Time (Process) Decomposition, Space Decomposition, and Scale Decomposition.

Previous research [1] using an advanced multi-domain topology optimization technique has shown a great promise for the crashworthiness design using the new technique. In this paper, we try to answer some fundamental questions regarding the crashworthiness design, which include: 1) what are the fundamental crash mechanisms of a general crash process; 2) how the uncertainties in the system will affect the crash behavior of a structure; and 3) what is the proper approach for the crashworthiness design optimization that will have needed effectiveness and efficiency. In this paper, three different kinds of uncertainties, uncertainties in the structural parameters, the modeling processes, and the loading and boundary conditions, will be considered to assess the effects of the uncertainties in the crash process. The possible crash mechanisms are then studied to provide an understanding for the design problem.

A multi-domain and multi-step topology optimization approach has been developed to address a wide range of structural design problems with manufacturability and other application concerns. The potential applications have been demonstrated in our previous work [1,2]. In this paper, we try to extend this method for vehicle crash design problem. The design process will be explained and examples will be provided to illustrate the potential application of this method for complicated crash design problems.

Computer Aided Engineering (CAE) has been successfully utilized in automotive industries. CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to the higher performance without building prototypes. Most automotive designers, however, cannot directly use CAE due to the sophisticated operations. In order to overcome this problem, we proposed a new concept of CAE, First Order Analysis (FOA). The basic ideas include (1) graphic interfaces using Microsoft/Excel to achieve a product oriented analysis (2) use the knowledge of the mechanics of materials to provide the useful information for designers, and (3) the topology optimization method using beam and panel elements. In this paper, outline of FOA and application are introduced

In FOA (First Order Analysis) any vehicle body structure might be interpreted as a collective simple structure that can be decomposed into 3 fundamental structure types. The first structure is the “BEAM”, whose cross sectional properties as well as its material dominates the mechanical behavior, the second is the “PANEL (shear panel, plate, and shell)”, whose mechanical behavior can be varied by changing its geometrical properties in the thickness direction, i.e. adding beads or flanges. The third structure is the “JOINT”, which connects the proceeding structures, and transfer complex three-dimensional loads with three-dimensional deformation. In the present work, we shall propose a methodology to identify a portion of an arbitrary FE model of an automotive body structure, with a “BEAM” structure in the FOA approach. In the latter chapter of this paper, cross section loads will be related with cross sectional properties in the aspect of the element strain energy concept.

A multi-domain and multi-step topology optimization approach is presented in this paper, which can be used to simplify the architecture/topological structure of an “optimum” structure obtained from the topology optimization process, and thus significantly improves the manufacturability of the final design. Examples will be given to illustrate how this approach can be applied to a realistic engineering design problem for developing lightweight and high-performance structures in next-generation ground vehicles.

The objective of this research is to verify the optimum design obtained from a topology optimization process. The verification is through both numerical analysis and physical test. It will be shown that the optimum topology obtained from an example topology optimization process is independent of the material used and the dimension/size of the structure. This important feature is then proved for more general cases through theoretical analyses, numerical simulations, and physical experiments. The result extends the applicability of the optimum design and simplifies the prototyping and test process thus will result in significant cost saving in building full-size prototypes and performing expensive tests. This work is a combined effort with theoretical, numerical and experimental methods. A multi-domain multi-step topology optimization technique [1] will be utilized to find the optimum structural design.

Computer Aided Engineering (CAE) has been successfully utilized in automotive industries. CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to the higher performance without building prototypes. Most automotive designers, however, cannot directly use CAE due to the sophisticated operations. In this paper, we propose a new breed of CAE, First Order Analysis (FOA), for automotive body designers. The basic ideas include (1) graphic interfaces using Microsoft/Excel to achieve a product oriented analysis (2) use of mechanics of materials to provide the useful information for designs, (3) the topology optimization method using function oriented elements. Further, some prototypes of software are presented to confirm the method for FOA presented here.

The shape and topology optimization method using a homogenization method is a powerful design tool because it can treat topological changes of a design domain. This method was originally developed in 1988 [1] and have been studied by many researchers. However, their scope of application in real vehicle design works has been limited where a design domain and boundary conditions are very complicated. The authors have developed a powerful optimization system by adopting a general purpose finite element analysis code. A method for treating vibration problems is also discussed. A new objective function corresponding to a multi-eigenvalue optimization problem is suggested. An improved optimization algorithm is then applied to solve the problem. Applications of the optimization system to design the body and the parts of a solar car are presented.

In various practical structural design problems, decision of a layout of material or stiffeners in the given design space satisfying some design constraints is the most difficult task for design engineers. Also, they must consider many possible cases for safety, performance and some other requirements. But it is very difficult to solve this type of layout (topology) problem by any conventional structural optimization techniques because its mathematical modeling of topology is so complex. To solve this problem, we employed the new topology optimization technique using the homogenization method that was recently introduced by Bensøe and Kikuchi. The method gives the minimum compliance design under certain material constraint. This technique was also extended to three dimensional shells and three dimensional solids by Suzuki and Kikuchi. In this paper, shape and topology optimization problem under multi-loading conditions is discussed.