基于多体动力学和有限元法的车身结构疲劳寿命预测

Fatigue Life Prediction of Autobody Structure Based on Multi-body Dynamics and Finite Element Method

根据耐久性试验中常用的整车台架试验方法,通过多体动力学模型仿真模拟整车在四轮路面激励下的运动状态,提取车身与底盘连接位置的载荷历程,采用有限元法分析动载荷作用下的车身结构响应;基于传统的应力-寿命方法(S-N方法)寻找车身薄弱环节,辨识危险零件应力"双轴性",并选择多轴疲劳损伤参量预测车身疲劳寿命。分析结果表明:结合多体动力学与多轴疲劳的寿命预测方法比传统的S-N方法能够获得更加合理的预测结果。

Multi-body dynamics model was employed to simulate the vehicle movement state under four-tire excitation by vehicle bench test method in durability test. After recording the load history at the connection between vehicle body and chassis, finite element method was used to analyze the structure response under dynamic loads. Then, a traditional S-N method was used to locate the weak point of autobody. By checking the biaxiality of stress state of the danger point, a multi-axial fatigue method was chosen to estimate vehicle structure life. Analysis results show that compared with traditional S-N method, the method can help to give a more reasonable result.