结合面静摩擦系数的统计模型

基于粗糙表面形貌的统计参数,综合考虑微凸体的完全弹性、弹-塑性和完全塑性三种变形机制,建立了结合面静摩擦系数的统计模型。该模型反映了静摩擦系数是由接触材料性能参数、表面形貌统计参数以及法向载荷共同决定的。通过仿真研究了微凸体高度的随机分布、塑性指数以及法向载荷等因素对静摩擦系数的影响规律。结果表明,修正的指数分布相比简单的指数分布对高斯分布有着较好的近似,且预测值近似等于高斯分布预测结果的均值;静摩擦系数随着塑性指数的增大而减小且变化趋缓;法向载荷增大时,静摩擦系数呈现减小的趋势,但在双对数坐标系下最大静摩擦力仍与法向载荷呈线性正比的关系。

Statistical model of static friction coefficient between joint surfaces

A statistical model for static friction coefficient of joint surfaces is developed based on statistical parameters for surfaces topography. The three deformation mechanisms of fully elastic, elastoplastic and fully plastic of an asperity are taken into account by statistical model. The static friction coefficient is determined by the material properties of rough surface, statistical parameters for surfaces topography and normal load. The effects of height distribution of the asperities, plasticity indices and normal load on the static friction coefficient are simulated. The results indicate that the modified exponential distribution is a good approximation to the Gaussian distribution in contrast to the simple exponential distribution. The estimation values of the modified exponential distribution are approximately equal to the mean values of the Gaussian distribution. The static friction coefficients decrease easing up by increasing plasticity indices. As the normal load is increased, the static friction coefficients decrease. However, the maximum static friction forces are linearly proportional to the normal load on a log-log plot.