粗糙体变形特性对接触过程的应力与应变的影响

Impacts of rough solid deformation properties on stresses and strains during contact process

运用W-M函数生成分形粗糙表面,建立一个新的双粗糙体接触模型,采用有限元方法模拟仿真了在粗糙体不同变形特性条件下的接触过程,并分析了接触表面的应力分布及不同接触位置的塑性应变随深度的变化规律.结果表明双粗糙接触表面的应力主要集中在个别的较高微凸体上,其应力最大值出现在微凸体肩部区域的位置;等效塑性应变在不同位置沿深度的变化,呈现出不同的规律,微凸体顶部区域沿深度方向的最大等效塑性应变均发生在次表层.材料表层下的塑性应变将会导致材料表层中的夹杂或微观缺陷周围萌生微孔和裂纹源.对比不同变形特性的模型,得出弹塑性-刚体模型的最大应力及应变值都大于弹塑性-弹塑性模型.

By using the W- M function to form fractal rough surfaces, a novel dual-rough-contact body is established. With application of finite element method for contact process simulation under different deformation conditions, the stress distribution, as well as the plastic strains of different positions with depths, is analyzed. From the results, it is found that the main strain concentrations occur on higher individual asperities, the maximum value of which appears in the position of asperity shoulder region. In addition,the equivalent plastic strains with positions versus depths are different, whereas the maximum equivalent plastic strain in the top area of the asperities with different depths appears in the subsurface. Further elaborated, the plastic strain under material surface produces the microporous and cracking source around mixtures or micro-effects in material surface. With comparison of different models of deformation properties, the maximum stress and strain values of plastic-elastic/rigid-body models are higher than those of plastic-elastic/plastic-elastic ones.