非均质材料的时变弹流润滑特性分析

Analysis on Transient Elastohydrodynamic Lubrication Characteristics of Inhomogeneous Material

通过将夹杂物所引起的表面特征位移引入到时变弹流润滑问题中,建立非均质材料时变弹流润滑模型,综合应用有限差分法、共轭梯度法及快速傅立叶变换算法进行数值求解,分析夹杂物对油膜厚度、压力及次表面应力的影响。结果表明:稳态条件下,硬夹杂物使得其上方的油膜压力增加、内部应力上升,而软夹杂物使得其上方的压力和内部应力均减小,但左右两边缘处出现应力集中;夹杂物的存在对油膜厚度的影响较小;当夹杂物体积和位置相同时,椭球体形夹杂物对油膜压力的影响比立方体形夹杂物显著,但含立方体形夹杂物的材料内最大von Mises应力对夹杂物弹性参数的变化更为敏感;时变条件下,非均质材料表面的油膜压力和内部的次表面应力均受动态效应的影响,呈现出与稳态下不同的特性。

A transient elastohydrodynamic lubrication(EHL)model of inhomogeneous materials was established through introducing the surface eigen-displacement caused by the inhomogeneity into the transient EHL model.Numerical simulations were conducted by combining the finite difference method,conjugate gradient method and fast Fourier transform method,and effects of the inhomogeneity on the film thickness,pressure and subsurface stress were analyzed.Results show that,under the steady condition,the stiff inhomogeneity increases both the film pressure above its position and the subsurface stress inside itself,while the compliant inhomogeneity exhibits the opposite trend and it causes stress concentration near the edges of the inhomogeneity.However,the effect of inhomogeneity on the film thickness is unremarkable.When the volume and position of the inhomogeneities are the same,the effects of ellipsoidal inhomogeneity on the film pressure are more significant than that of cubical inhomogeneity,but the maximum von Mises stress of the materials with the cubical inhomogeneity is more sensitive to the changes of the elastic parameters of the inhomogeneity.Under the transient condition,the film pressure and subsurface stress of the inhomogeneous materials are affected by the transient effect,showing different properties from those under the steady condition.