对由矩形管梁拼焊而成的客车骨架结构进行轻量化研究． 首先计算了矩形管梁单元的截面特性，并定义了客车骨架的静态弯扭刚度响应与动态频率刚度响应． 其次建立
了客车结构优化数学模型:目标函数是车身骨架质量;设计变量是矩形管截面宽度、高度与厚度;约束是弯扭刚度与频率刚度． 然后推导了响应对设计变量的灵敏度信息，并采用序列线性规划求解了该非线性优化模型． 最后通过数值算例验证了该模型能在满足约束条件的前提下高效地获得轻量化的客车最优结构．

In order to achieve a lightweight structure of the bus frame consisting of rectangular tubes,first,the cross-sectional properties of the rectangular tubes are calculated,and the responses of static bending stiffness,static torsional stiffness，and dynamic frequency stiffness are respectively defined.Next,a structural optimization model of the bus frame is constructed.In the model，the objective function is the structural mass,the design variables are the cross-sectional breadth,height,and thickness of the rectangular tubes,and the constraints are the bending,torsional and frequency stiffness.Then,the sensitivity information of the responses with respect to the design varia- bles is derived,and the nonlinear optimization model is solved through the sequential linear programming.Finally， by a numerical example,it is proved that the proposed method can efficiently acquire the optimal bus frame that satisfies the constraint conditions.