非均质材料非牛顿弹流润滑特性及疲劳寿命研究

Analysis of Non-Newtonian Elastohydrodynamic Lubrication Characteristics and Fatigue Life of Inhomogeneous Material

滚动轴承的润滑性能及寿命与润滑剂的流变特性及材料的非均质性息息相关。本文在建立非牛顿弹流润滑模型、非均质模型及滚动接触疲劳寿命模型的基础上,考察了滑滚比、润滑剂特征剪应力以及夹杂物体积比对非均质材料润滑性能和疲劳寿命的影响。数值模拟结果表明,夹杂物的存在会引起油膜压力和次表面应力的显著变化,造成疲劳寿命的降低;滑滚比的增加和特征剪应力的增大均会引起最大von Mises应力的增加和疲劳寿命的降低,且相对于含硬夹杂物的材料而言,含软夹杂物的材料的疲劳寿命对滑滚比和特征剪应力的变化更为敏感;夹杂物在材料中所占的体积比越大,非均质材料的疲劳寿命越低。

The lubrication characteristics and fatigue life of rolling bearings have close relationships with the rheological properties of lubricants and imperfections of materials.The non-Newtonian elastohydrodynamic lubrication (EHL) model,inclusion model and rolling contact fatigue life model were established,the effects of the slide-roll ratio,characteristic shear stress of non-Newtonian fluid and volume fraction of inhomogeneities on the lubrication properties and fatigue life of inhomogeneous material were investigated.The simulation results show that the existence of inhomogeneity can cause remarkable changes in the film pressure and subsurface stress,and induce the reduction of fatigue life.With the increasing of the slide-roll ratio and the characteristic shear stress,the maximum value of von Mises stress increases and the fatigue life decreases.The fatigue life of the material containing compliant inhomogeneity is more sensitive to the changes in the slide-roll ratio and the characteristic shear stress than that of the material containing stiff inhomogeneity.Furthermore,the fatigue life of the inhomogeneous material decreases with the increasing of volume fraction of inhomogeneities.