Impact Bar Made of Ultra High-Strength Steel *

The original material of the side impact bar is replaced with ultra high-strength steel. The section dimensions of the side impact bar are considered as design varieties, and its minimum weight is considered as the optimization object. The maxi­ mum displacement and residual deformation in door sinking stiffness condition as well as the impact forces under different dis­ placements in side impact condition are considered as constraints of optimization. Sampling points are obtained by optimal Latin square design of experimental method. The multidisciplinar y design optimization, which approximates systems with door sinking stiffness and side crashworthiness, is constructed using polynomial response surface regression. Comparing the prediction result of the polynomial response surface regression approximate model and the computer result of the finite element model, the approx­ imate model of the former shows higher accuracy. The approximate systems are optimized using the method of feasible direc­ tions. The door sinking stiffness and side crashworthiness are improved, and the weight of the side impact bar is reduced by 34.7%.