分形特征表面接触磨损模拟

Contact and Wear Simulation Between Fractal Surfaces

为实现粗糙表面微观接触磨损的精确预测,根据分形理论对传统的只考虑弹性-塑性两状态的二维分形接触模型进行了修正,并构建了包含弹性-弹塑性-塑性完全状态的三维粗糙表面分形接触模型。通过去除塑性接触微凸体在截断平面作用下形成的球台方法来模拟微观磨损,磨损系数由被去除的球台体积与总接触微凸体体积之比来表征,采用数值仿真分析了磨损系数与分形参数、载荷和材料等因素间的依赖关系。计算结果表明,磨损系数随表面粗糙程度的增大而增大,随接触载荷的增大而减小并趋于相对稳定。接触副材料属性决定了微凸体临界接触面积,进而影响了磨损系数。该模型给出了微观磨损机理的数学描述,为界面接触磨损研究提供了新思路。

The traditional 2D fractal contact theory only takes elastic and plastic contact of asperities into account.To predict contact and wear microscopically,a novel model was proposed which includes all of the elastic,elastic-plastic and fully plastic deformation regimes for asperity of fractal surface.A generalized adhesive wear analysis was developed for 3D fractal surfaces in normal contact.Worn particles can be modeled by the removal of material from the spherical cap for fully-plastic asperity truncated by a rigid plane.Wear progress was discretized into several incremental steps,and characterized as wear rate to define as the total volume of wear particles divided by the total volume of all contacting asperities.Contact and wear problem were examined numerically to illustrate the dependence of wear rate on fractal parameters,loads and material properties.The numerical results indicate that wear rate increases with the increasing surface roughness.As the normal load is increased,wear rate decreases and tends relatively static.Material properties have influences on the critical truncated contact area and wear rate.