汽车扭力梁式后悬架轴头载荷谱仿真分析

Simulation of Load Time History on Spindle Nose and Fatigue Life Assessment of Rear Torsion Beam

在汽车后悬架结构优化设计问题的研究中,针对悬架系统中存在非线性弹性部件使得轴头载荷难以通过解析法获得的问题,为了获得汽车扭力梁式后悬架轴头更为准确的载荷谱,提出了一种求解汽车扭力梁式后悬架轴头载荷谱的计算机仿真方法。根据迭代逼近原理,采用牛顿下山法为迭代收敛判断方法,结合Simulink联合仿真技术,迭代仿真得到后扭力粱轴头的载荷谱。采用系统刚柔耦合多体动力学模型,通过分析系统传递函数,反求得到轴头载荷动态仿真的激励信号。以样车道路试验实测的后扭力梁弹簧垂向位移为参考,运用牛顿下山法仿真得到轴头载荷时间历程。改进的仿真方法的准确性在后扭力梁整车的道路模拟台架试验上得到验证。研究证明,仿真结果与实际吻合较好,其为结构设计优化和振动疲劳评估提供基础。

Aiming at revealing fatigue failure mechanism and precisely predicting fatigue life for rear torsion beam suspension of the car, load time history on spindle nose was simulated and verified via dynamic analysis and test, in- tegrating multibody dynamic analysis and finite element method. Dynamic simulation model of rear torsion beam sus- pension was established based on ADAMS according to load and boundary conditions under operating mode. Then, the transfer function of system was solved by sweep frequency technique, and load time history on spindle nose was acquired by dynamic iterative simulation after FE model of rear torsion beam suspension was verified by Modal test method. Based on co-simulation technology of ADAMS and SIMULINK, load time history on spindle nose was ob- tained through dynamic simulation by putting spring vertical displacement test as reference and loaded on spindle nose of rear torsion beam. Comparing displacement response measured on real vehicle with iterative, load spectrum of rear torsion beam on spindle nose was derived by putting Newton downhill method as judge for iteration convergence. The test result has verified the iterative method effective by vehicle road simulation test-bed experiment of the rear torsion beam. It has provided a basis for structural design optimization and fatigue assessment.