中文摘要：

建立了由Timoshenko梁单元、Mindlin四边形板单元及接头单元构成的概念车身框架结构简化模型,并对该复杂结构进行了参数优化。为简易求解,将梁单元的力学特性参数转为截面几何变量,以梁单元、板单元截面几何参数为设计变量,以车身框架质量最小、刚度最大为目标,建立多目标优化模型,并采用Pareto遗传算法进行求解。算例表明：经过有限代进化,所有个体全部落入可行域内,并最终找到较优解;优化后的模型车身质量减轻,刚度提高。

英文摘要：

A simplified model for the frame structure of conceptual car body consisting of Timoshenko beam elements,Mindlin quadrilateral plate elements and joint elements is built.For facilitating solution,the mechanical property parameters of beam element are transformed to cross-sectional geometric variables.A multi-objective optimization model is established with the cross-sectional geometric parameters of beam and plate elements as design variables and the minimum mass and maximum stiffness of car body frame as objectives,the solution is searched by using Pareto genetic algorithm.The results of example calculation show that all the individuals fall into the feasible region through finite generations of evolution and finally the better solutions are found.After model optimization,the mass of car body reduces and the stiffness rises.