基于动力学仿真和有限元分析的曲轴疲劳寿命计算

Crankshaft Fatigue Life Calculation Based on Dynamic Simulation and FEA

在对某型六缸汽车发动机曲轴系动态仿真和对曲轴进行静态有限元分析基础上对曲轴的疲劳寿命进行了计算。首先对曲轴系进行动态仿真,得到曲轴连杆颈处的载荷和载荷谱,载荷作为曲轴有限元分析的力边界条件,而载荷谱经过简化,得到计算曲轴疲劳寿命的载荷谱,同时利用弹簧单元对主轴颈处的弹性支撑实际状况进行了模拟,也考虑了相邻拐的影响,然后在有限元分析的基础上分别利用S-N和局部应变法计算了曲轴的疲劳寿命,得到的结果说明传统的计算过于保守,这不但对曲轴的设计和优化有一定的意义;也说明再制造发动机时直接利用曲轴其寿命是可靠的,足以维持下一个生命周期。

The paper calculated the fatigue life of crankshaft of a six-cylinder automobile engine, based on dynamic simulation and finite element analysis. First, the loadings exerting on crankpins, taken as force boundary conditions of finite element analysis（FEA）, and load spectrum, taken as load spectrum of fatigue life calculation simplified, were gained through dynamic simulation. Meanwhile, the elastic supports on main journal were simulated using elements of ground spring and the mutual effect of adjacent crankpin was considered. Then the fatigue life of the crankshaft was respectively calculated using S-N method and local stress -strain method, which result in that the traditional calculation is too conservative. The result not only illuminated that the fatigue life of crankshaft is adequate w.hen it is remanufactured, but also is of significant to design and optimization of crankshaft.