考虑柔性副车架的某轿车操纵稳定性优化研究

Optimization study of handling stability of a car considering flexible subframe

一般车辆仿真是在副车架为刚性的假设下进行研究的,然而副车架实际上为柔性。为研究副车架柔性化和材料属性变化对操纵稳定性优化的影响,利用HYPERMESH软件模态计算得到前副车架的柔性体文件,并进行模态分析,避免其与发动机和车身产生共振。将柔性前副车架导入ADAMS软件替换原有刚性前副车架,建立某轿车具有不同材料属性的柔性前副车架刚柔耦合模型,进行悬架K&C仿真和整车操纵稳定性仿真对比研究。以车辆操纵稳定性为优化目标,利用NSGA-Ⅱ算法对前副车架衬套刚度参数进行多目标优化设计。结果表明,柔性前副车架材料属性变化后的弹性变形会对悬架系统受力产生影响,从而改变悬架K&C特性,进而使整车刚柔耦合模型的操纵稳定性发生改变。改变材料属性也会使得前副车架与悬架和车身铰接处衬套刚度参数的多目标优化结果发生变化。多目标优化后横摆角速度增益、车身侧倾角增益和侧向加速度的延迟时间均降低,整车刚柔耦合模型操纵稳定性得到改善。

Generally,vehicle simulation is studied under the assumption that the subframe is rigid.However,in reality,the subframe is flexible.In order to study the influence of subframe flexibility and material property change on the handling stability optimization,HYPERMESH software modal calculation was used to obtain the flexible front subframe file,and modal analysis was carried out to avoid its resonance with the engine and body.The flexible front subframe was imported into ADAMS software to replace the original rigid front subframe,and a rigid-flexible coupling model of a car with different material properties of the flexible front subframe was established,and the K&C simulation of the suspension and the simulation of the handling stability of the whole vehicle were carried out for comparative study.The NSGA-Ⅱalgorithm was used to optimize the design of the front subframe bushing stiffness parameters with the optimization objective of vehicle handling stability.The results show that the elastic deformation after changing the material properties of the flexible front subframe affects the force on the suspension system,which changes the K&C characteristics of the suspension,and then changes the handling stability of the rigid-flexible coupling model of the whole vehicle.Changing the material properties also causes the results of the multi-objective optimization of the bushing stiffness parameters at the articulations of the front subframe with the suspension and the body to change.After the multi-objective optimization,the yaw rate gain,the body roll angle gain,and the delay time of lateral acceleration are all reduced,and the handling stability of the whole vehicle rigid-flexible coupling model is improved.