Fractal model of thermal elasto-plastic contact of rough surfaces

Abstract

Without considering the influence of heat, existing fractal contact models are not applicable to analyze the contacts when the temperature changes. For this problem, the normal load model and the normal stiffness model of thermal elasto-plastic contact of rough surfaces are developed respectively in this paper. The proposed model is based on the normal contact mechanics model of fractal theory of anisotropic and thermal elasto-plastic contact theory which can be used to characterize the rough surface thermodynamic properties. Then the validity of the model is verified. Finally, the influence of main parameters on the total normal load and the whole normal stiffness of thermal elasto-plastic contact at the interface is analyzed by contact simulation. The results show that the total normal load of thermal elasto-plastic contact increases with the increases of temperature. The whole normal stiffness of thermal elasto-plastic contact increases with increasing coefficient of linear expansion, scale factor, temperature difference or fractal dimension, but decreases with increasing fractal roughness. This model expands basic theory and applications of traditional models, and can be used to calculate and analyze the contacts when the temperature changes.

摘要

针对现有分形接触模型没有考虑热应力的影响、不适用于结合部温度变化的问题,基于各向异性分形理论和热弹塑性接触理论,本文分别建立了粗糙表面热弹塑性接触的法向载荷模型和法向刚度模型,并验证了模型的有效性,该模型可用于表征粗糙表面的热力学特性。通过数字仿真,分别分析了主要参数对粗糙表面热弹塑性接触法向载荷和法向刚度的影响。结果表明:热弹塑性接触法向载荷随结合部温差的增大而增大; 热弹塑性接触法向刚度随着线膨胀系数、比例系数、温差、分形维数的增大而增大,随表面粗糙度的增大而减小。该模型是对传统模型在基础理论和应用范围上的拓展,可用于计算和分析工程实际中大量存在的结合部温度发生改变的接触情况。