纯电动轿车铝合金转向节结构轻量化研究

Research on Lightweighting of Aluminum Alloy Steering Knuckle Structure for Pure Electric Cars

为了实现纯电动轿车底盘轻量化,提出了一种拓扑优化与参数优化相结合的转向节结构优化方法。建立转向节实体模型,基于经典工况下转向节的受载情况对其进行静强度有限元分析。运用固体各向同性材料惩罚模型,建立了以单元相对密度为设计变量、柔度最小为目标函数、体积为约束函数的拓扑优化模型,对转向节进行多工况拓扑优化。根据拓扑优化结果,以转向节关键部位的厚度为设计变量,在样本空间内建立响应面近似模型,利用多目标遗传算法对转向节进行了参数优化。2次优化结果表明:铝合金转向节质量减少了22.82%,相比优化前、优化后的转向节在过坎、路坑制动、转向工况下最大应力分别减小了13.51%、36.80%、0.77%,4倍满载工况下应力略有增加,优化结果满足设计要求。通过ANSYS和nCode联合仿真,采用Miner线性疲劳累积损伤计算方法对优化后的转向节进行疲劳仿真验证,计算结果满足疲劳强度设计要求。

In order to realize the lightweight of the chassis of a pure electric car,a method of steering knuckle structure optimization combining topology optimization and parameter optimization was proposed.A solid model of the steering knuckle was established,and a static strength finite element analysis was carried out based on the loading condition of the steering knuckle under classical working conditions.By using the solid isotropic material penalty model,a topology optimization model with unit relative density as design variable,minimum flexibility as objective function and volume as constraint function is established for multiple working conditions.According to the results of topology optimization,the thickness of the key parts of the steering knuckle is taken as the design variable,the response surface approximation model is established in the sample space,and the steering knuckle parameters are optimized by using multi-objective genetic algorithm.The results of the two optimizations show that the mass of the aluminum alloy steering knuckle is reduced by 22.82%,the maximum stress of the optimized steering knuckle is reduced by 13.51%,36.80%,and 0.77%respectively under the conditions of crossing,pothole braking and steering.The optimization result meets the design requirements although the stresses while the condition of 4 times full load are slightly increased.Through the joint simulation of ANSYS and nCode,the optimized steering knuckle is verified by fatigue simulation based on the Miner linear fatigue cumulative damage calculation method.