In automotive body structural design, Computer Aided Engineering (CAE) has been widely used in order to evaluate noise, vibration, harshness (NVH). A CAE engineer has usually used a large-scale finite element model exceeding 1 million degrees of freedom to improve NVH performance criteria. It is, however, difficult for a CAE engineer to propose the good modification candidate for the NVH reduction to an automotive designer. Because the FEM calculation is very time-consuming and many design candidates must be considered for a large-scale model. Therefore quick and effective design calculation procedures are requested to overcome these problems, especially in the recent virtual prototyping development process. In this paper, a new optimal design method using a reduction scheme based on the physical coordinates under many design constraints regarding the crashworthiness is proposed in order to overcome above problems. That is, we determine the appropriate location and additional scalar spring constants by minimizing the acceleration of the observation grid. The effectiveness and availability of this method are confirmed using an example.
