A normal mechanical model for elastic-plastic contact of rough surface

An elastic-plastic mechanical model was proposed to describe the normal contact load and area of the rough surface. The problem can be considered in three separated contact phases, the ideally elastic phase, the mixed elastic-plastic phase and the fully plastic phase. In the ideally elastic phase, Hertz's elastic contact formulations were used; in the fully plastic phase, the classical fully plastic contact modal of Abbott and Firstone was used; and in the mixed elastic-plastic phase, the contact behaviors were approximated by one-order power function interpolation. The contact model of rough surfaces was then formulated by using the probability statistics theory. The proposed model was compared with the ideally elastic model, CEB model, ZMC model, and KE model. The results show that the proposed model can better model the relation between the contact load and deformation of asperity, and the result agrees well with that of the KE model and ZMC model. With the increase of mean separation of rough surfaces, the total contact load decreases. The plasticity index has a great effect on the contact load of different model, and larger plasticity index induces more difference.