中文摘要：

提出一种新型梯度强度立柱结构，使侧翻时客车立柱不同位置的强度与受力匹配。对梯度立柱分析表明：新型梯度强度立柱结构明显提高了客车侧翻安全性能。结合最优拉丁方实验设计和径向基近似技术，构建了设计响应的高精度近似模型，并采用多目标遗传算法对其寻优。优化结果表明：通过对梯度强度立柱结构的强度与壁厚的合理匹配，不仅使得客车的侧翻安全性得到较大的改善，而且达到了客车轻量化设计的目的。

英文摘要：

In order to make the strength of the pillar in different locations match with the impacting force,a new gradient strength pillar structure is proposed in this paper.The rollover simulation analysis for gradient pillar shows that the gra-dient strength pillar structure obviously improves rollover safety of the bus.The paper establishes high precision approxi-mate models of design response by combining optimal latin hypercube experimental design with radial basis function （RBF）approximation techniques,and multi-objective optimization design is performed based on approximate models of design responses by using the multi-obj ective genetic algorithm （NSGA-Ⅱ）.The optimization results show that a reason-able match of strength and wall thickness for the pillar structure,not only can improve bus rollover security greatly,but also can achieve the purpose of bus lightweight design.