基于以界面力度量的车身承载度的客车结构优化研究

A Study on Coach Structure Optimization Based on Load Ratio of Vehicle Body Measured by Interface Force

在传统的评价方法基础上,采用车身结构承载度的另一种度量方法——界面力法,对某半承载式客车的车身承载度进行了分析,并以提高车身承载度为目标,对该客车的结构进行了改进。首先,通过计算结构应变能密度发现车身结构承担载荷较少,没有充分发挥车身材料的性能,且不同环结构承担的载荷不同,整车后部环的承载度大于前部的环。其次,根据应变能分析结果选定底架部分零件(前后纵梁和行李仓构件)作为优化对象,并以它们的截面尺寸和厚度作为优化变量,制定实验方案并进行了优化。对改进后的结构与原结构的性能(强度、弯曲刚度、扭转刚度和低阶模态)进行了对比分析。结果表明,优化的结果比较理想,说明界面力法能准确地计算出车身各个环结构的承担载荷和载荷在车身上的分布情况,为有针对性地进行结构改进提供了优化方向。文中采用的车身承载度指标能有效权衡车身和底架的材料分配,可作为衡量客车结构合理性的一个指标和结构优化目标。

On the basis of traditional methods, another measuring method for load ratio of vehicle body, i. e. interface force method is adopted to analyze the load ratio of a semi-monocoque body of a coach and modify its structure with increasing its load ratio as objective. Firstly it is found by the calculation of the strain energy density of structure that the body structure bears lesser load, its material insufficiently fulfills its function, and different rings bear different loads with the load ratio of rings in rear position higher than those in front position. Then based on the results of strain energy density analysis,some parts in under- frame,such as front and rear longitudinal rails and luggage compartment are selected to be optimized,with their section size and thickness taken as optimization variables,and the performances of structure modified （ strength,bending stiffness,torsional stiffness and low-order modal frequencies） are analyzed and compared with those of original one. The results show that the outcome of optimization is satisfactory,demonstrating that interface force method can accurately calculate the loads borne by each ring structure of body and their distribution, guiding the direction of targeted structure modification and optimization. The load ratio indicator adopted can effectively judge the material distribution between the body and underframe of vehicle and can be an indicator of measuring the rationality of coach structure and an objective of optimization.