考虑基体变形的混合润滑结合面接触特性

Contact Characteristics of Joint Surfaces Considering Bulk Substrate Deformation in Mixed Lubrication

为研究混合润滑状态下粗糙表面基体变形对结合面接触特性的影响,建立了考虑基体变形的结合面接触刚度模型。首先,通过单微凸体-基体系统模型分别求解微凸体和基体的接触刚度,利用不动点迭代法获得微凸体真实变形量;其次,基于分形理论建立结合面固体接触刚度模型,通过固体接触刚度获得液体介质的接触刚度。根据仿真结果分析了基体变形、粗糙表面形貌以及润滑介质对结合面接触特性的影响规律。结果表明:当真实接触面积一定时,通过新模型计算的法向载荷小于忽略基体变形的模型;在接触前期,结合面的接触刚度主要由液体介质接触刚度主导,随着真实接触面积的增加,液体接触刚度占总刚度的比率越来越小,最后转变为固体的接触刚度主导结合面的接触刚度。该模型为研究混合润滑状态下结合面的接触特性提供了理论基础。

In order to investigate the effect of bulk substrate deformation on the micro contact characteristics of joint surfaces in mixed lubrication,a contact stiffness model of joint surfaces considering bulk substrate deformation is proposed.Firstly,the asperity contact stiffness and bulk substrate contact stiffness are obtained by the single asperity-bulk substrate system model,and the contact deformation of asperity is determined by the fixed point iteration method.Then,the normal contact stiffness model of the solid surface is established based on fractal theory with considering bulk substrate deformation.Furthermore,the solid contact stiffness is used to obtain liquid contact stiffness model.The results show that the normal load from the proposed model is smaller than the model that ignores bulk substrate deformation,when the real contact area is constant.Meanwhile,the contact stiffness of joint surfaces is mainly dominated by liquid contact stiffness in the early stage of contact.However,the ratio of the liquid contact stiffness to the total stiffness decreases with increasing the real contact area.Finally,the solid contact stiffness dominatesjoint surfaces.This model provides a theoretical basis for studying the contact characteristics of joint surfaces in mixed lubrication.