Purpose

The purpose of this paper is to provide a static friction coefficient prediction model of rough contact surfaces based on the contact mechanics analysis of elastic-plastic fractal surfaces.

Design/methodology/approach

In this paper, the continuous deformation stage of the multi-scale asperity is considered, i.e. asperities on joint surfaces go through three deformation stages in succession, the elastic deformation, the elastic-plastic deformation (the first elastic-plastic region and the second elastic-plastic region) and the plastic deformation, rather than the direct transition from the elastic deformation to the plastic deformation. In addition, the contact between rough metal surfaces should be the contact of three-dimensional topography, which corresponds to the fractal dimension D (2 < D < 3), not two-dimensional curves. So, in consideration of the elastic-plastic deformation mechanism of asperities and the three-dimensional topography, the contact mechanics of the elastic-plastic fractal surface is analyzed, and the static friction coefficient nonlinear prediction model of the surface is further established.

Findings

There is a boundary value between the normal load and the fractal dimension. In the range smaller than the boundary value, the normal load decreases with fractal dimension; in the range larger than the boundary value, the normal load increases with fractal dimension. Considering the elastic-plastic deformation of the asperity on the contact surface, the total normal contact load is larger than that of ignoring the elastic-plastic deformation of the asperity. There is a proper fractal dimension, which can make the static friction of the contact surface maximum; there is a negative correlation between the static friction coefficient and the fractal scale coefficient.

Originality/value

In the mechanical structure, the research and prediction of the static friction coefficient characteristics of the interface will lay a foundation for the understanding of the mechanism of friction and wear and the interaction relationship between contact surfaces from the micro asperity-scale level, which has an important engineering application value.

中文翻译：

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弹塑性分形表面的接触力学和粗糙尺度的静摩擦分析

目的

本文的目的是基于弹塑性分形表面的接触力学分析，提供粗糙接触表面的静摩擦系数预测模型。

设计/方法/方法

本文考虑了多尺度粗糙的连续变形阶段，即关节表面的粗糙连续经历了三个变形阶段，即弹性变形，弹塑性变形（第一弹塑性区域和第二弹塑性区域）。 -塑性区）和塑性变形，而不是直接从弹性变形过渡到塑性变形。另外，粗糙金属表面之间的接触应该是三维形貌的接触，它对应于分形维数D（2 <D <3），而不是二维曲线。因此，考虑到凹凸的弹塑性变形机理和三维形貌，分析了弹塑性分形表面的接触力学，

发现

法向载荷和分形维数之间存在一个边界值。在小于边界值的范围内，法向载荷随分形维数的减小而减小；在大于边界值的范围内，法向载荷随分形维数增加。考虑到粗糙表面在接触表面上的弹塑性变形，总的法向接触载荷要大于忽略粗糙表面的弹塑性变形的载荷。有适当的分形维数，可以使接触表面的静摩擦最大。静摩擦系数和分形比例系数之间存在负相关。

创意/价值

在机械结构中，界面静摩擦系数特性的研究和预测将为从微观粗糙度尺度上理解摩擦磨损机理和接触面之间的相互作用关系打下基础。重要的工程应用价值。