Recently, the car industry is confronted with various demands such as light weight and safety for a crash accident. But to achieve a light and safe car, design optimization process is indispensable due to the many constraints in the car.
If we separate the optimization methods, we can say both sensitivity base method and non- sensitivity base method. The Sensitivity base method gives good results. But in the non-linear problem such as crash, the Sensitivity base method requires too much calculation time and high-powered computer. So the response surface method based on the non-sensitivity method is applied to enhance the crash performance. Because the way to construct the response surface is obtained by the least square method, this response surface have the only the polynomial terms. So the optimization process is very simple and easily observes the global maximum and minimum.
In this paper, the response surface method based on the non-sensitivity is used to optimize the crash performance of the auto-body members. And the applied auto-body members are the simple shape tubes, and the front side member. The cross section of the simple tube is circular type, and square type. And according to these results, the member for the crash needs enough thickness to obtain the enough stiffness. And finally, the front side member is the structure equipped under the auto-body and the major function of the front side member is the impact energy absorption during the frontal crash. To construct the response surface, we must determine the design points. And these design points can be obtained by experiments design. After determination of the design points, 27 calculations must be done by the commercial FEM Program LS-DYNA 3D. With the response surface method and the commercial fern program such as LS-DYNA, the deformation, the absorbed energy and the mass are constructed and then are used to optimize the crash performance of the front side members. The crash performance is improved and the deformation pattern is improved.
