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The front rail, as one main energy absorption component of vehicle front structures, should present steady progressive collapse along its axis and avoid bending collapse during the front oblique impact, but when the angle of loading direction is larger than some critical angle, it will appear bending collapse causing reduced capability of crash energy absorption. This paper is concerned with crashworthiness design of the front rail on a vehicle chassis frame structure considering uncertain crash directions. The objective is to improve the crash direction adaptability of the front rail, without deteriorating the vehicle's crashworthiness performance. Magic Cube (MQ) approach, a systematic design approach, is conducted to analyze the design problem. By applying Space Decomposition of MQ, an equivalent model of the vehicle chassis frame is generated, which simplifies the design problem.

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.

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.

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.