考虑微凸体弹塑性变形的结合面分形接触模型

Fractal Contact Model of Joint Interfaces Considering Elastic-plastic Deformation of Asperities

基于分形接触理论,建立了考虑微凸体弹塑性变形的结合面分形接触模型。通过对所建模型的数值仿真,直观揭示了接触载荷与实际接触面积间的非线性关系,以及弹塑性变形对结合面接触的影响。仿真结果表明,接触载荷随着实际接触面积的增加而增加,两者呈近似线性关系。同样的接触面积下,接触载荷随着分形粗糙度系数G的增加而增加,随着分形维数D变化的规律比较复杂。弹塑性接触面积占总接触面积的比例随着接触面积的增加而略微减小,同时随着G的增加而增加。弹塑性接触面积所占比例与D的关系是复杂的。弹塑性接触载荷不可忽略,弹塑性载荷占总载荷的比例与粗糙度系数及接触面积无关,只随着分形维数的增加而减小。忽略微凸体弹塑性接触时,接触载荷会略大于考虑弹塑性接触时的结果,误差在5%～60%之间,误差随着分形维数的增加而减小。

A fractal model of joint interfaces was established based on fractal contact theory. The elastic-plastic deformation of asperities was taken into account in the model. By numerical simulation, the nonlinear relationship between the contact force and the real contact area was obtained, as well as the effects of elastic-plastic deformation on the contact of joint interfaces. The result showed that the contact force increased nearly linearly with the real contact area. The contact force decreased due to the increase of fractal roughness parameter G with the same contact area, but complicatedly varies with the fractal dimension D. The share of elastic-plastic contact area decreased with the increase of real contact area, increased with the increase of G, and complicatedly varies with D. The share of elastic-plastic was large enough and can not be ignored. It decreased with the increase of D. When the elastic-plastic deformation was overlooked, the contact fore was slightly larger than the results involved the elastic-plastic deformation. The error percentage lied within the range 5%-60% , which decreased with the increase of D.