应用多体有限元法预测车体结构疲劳寿命

FATIGUE LIFE PREDICTION APPLIED TO CAR-BODY STRUCTURE WITH MULTI-BODY DYNAMICS AND FEM

利用多体动力学和有限元法结合的混合方法对机车车体结构疲劳寿命进行仿真研究。首先在SIMPACK中建立机车整车的多体系统动力学模型,根据不同的载荷工况计算其载荷时间历程;其次根据有限元准静态应力分析法,获得车体结构的准静态应力应变影响因子(stresses influence coefficient,SIC),再利用模态分析技术获得车体结构固有频率和模态振型,以及确定车体结构危险点位置。基于危险应力分布的动载荷历程,结合车体材料的S—N曲线以及Palmgren-Miner损伤理论,利用FE-FATIGUE软件的安全强度因子分析法和WAFO(wave analysis for fatigue and oceanography)技术进行标准时域的车体结构疲劳寿命预测,其中包括应力应变的循环计数、损伤累积和寿命预测。实测结果和仿真结果相互对比表明,这种方法可以有效预测车体结构的疲劳寿命,其精度和动力学与有限元模型的精度有关。

With multi-body dynamic （MBD） and finite element method （FEM）, a hybrid method of locomotive car-body structure fatigue life simulation research can be proposed here. Firstly, one full locomotive MBS （multibody system） dynamic model is created in software SIMPACK and the load time histories of structure critical points in different load cases are calculated at the same time. Second- ly, stresses influence coefficient（SIC）is yielded by means of quasi-static stress/strain analysis with software ANSYS. And modal analysis is used to determine natural frequencies, mode shapes and the critical locations of the car-body structure. Based on the danger stresses distribution and dynamic load time histories, combining with material S--N curve, car-body structure fatigue life can be estimated with Palmgren-Miner damage theory. The standard time histories fatigue life prediction method involves stress or strain cycle counting, damage accumulation, and life was estimated in software FE-FATIGUE with factor of safety technology and WAFO （wave analysis for fatigue and oceanography） technology. The results between actual test and simulation are valid to evaluate car-body structure fatigue life and the pre- diction precision depends on the precision of multi-body model and FEM model.