柴油机凸轮-挺柱的接触应力分析及疲劳寿命估算

Contact Stress Analysis and Fatigue Life Estimation for Cam-Tappet of Diesel Engine

针对某柴油机配气机构凸轮-平底挺柱摩擦副,综合采用多体动力学方法、Hertz理论和有限元静力分析方法,确定凸轮桃尖附近为危险位置。针对此位置,采用Abaqus/Standard准静态分析方法,分析了表面摩擦因数对凸轮-挺柱的Von Mises等效应力、切应力的影响。结果表明,随着摩擦因数的增大,Von Mises应力和切应力逐渐增大,最大Von Mises应力的位置从表面下一点逐渐移向表面。最后基于修正的Manson-Coffin寿命预测方法,对挺柱在不同摩擦因数下不同深度处的接触疲劳寿命进行了估算。研究发现,随摩擦因数增大,接触疲劳寿命逐渐减小,接触疲劳裂纹萌生位置逐渐靠近表面。

For the cam-tappet pair of valve train for a diesel engine ,the multi-body dynamics method ,Hertz theory and the fi-nite element static analysis method were used to determine the cam peach tip area as the damage position .With Abaqus/stand-ard quasi-static analysis method ,the influences of surface friction coefficients on Von Mises equivalent stress and shear stress were analyzed .The results show that Von Mises stress and shear stress increase and the maximal Von Mises stress position ex-tends to the surface from the below with the increase of friction coefficients .The tappet contact fatigue life estimation of differ-ent depths under different friction coefficients based on the modified Manson-Coffin life prediction method shows that the con-tact fatigue life decreases and the contact fatigue crack initiation approaches the surface gradually with the increase of friction coefficient .