Simulation Of The Transfer Process During Friction Of The PTFE Composites

The transfer film formed during friction has a decisive influence on the tribological performances of the polymer composites. Generally, the study method of the transfer film has been the experimental method, the final result can only be observed. The dynamic process of the transfer film formation can not be observed. It is very important to understand the dynamic process of transfer film formation to realize the control of the transfer film and the optimization of the tribological performance. Therefore, it is very necessary to investigate the dynamic process of the transfer film formation with the help of numerical simulation. In view of this, the transfer process of the PTFE-45steel frictional couple was simulated by PFC2D particles flow program developed on the basis of the discrete element method, which directly displayed the dynamic friction transfer process. The simulated results are as follows:(1) The interface of the PTFE-45steel frictional counterparts is dynamic. This area can be basically divided into three layers:1) the layer directly contacted on the counterface, the so-called "transfer film", is most stable;2) the middle layer is a "surging layer", the parts being out of PTFE body materials but not the contact part and the shedding of particles from the previous transfer film and back to the friction interface, we call this layer "surge layer";3) the upper layer is the elastic-plastic deformation part of the PTFE body material, which may drag and drop into the "surging layer" or "transfer film" in the next period of friction.(2) The force direction applied on the PTFE particles obviously follows the speed direction and maintain consistency with the speed direction.(3) The effect of speed on the transfer and wear of PTFE-45steel friction system:at low speeds, transfer speed is faster and the transfer particle numbers are more. As the speed increases, in the same sliding distance, the final transfer particles decrease, the wear particles also decrease, the wear rate increases.(4) The effect of load on the transfer and wear of PTFE-45steel friction system:higher load corresponds to the higher level of dynamic transfer particles and the more total wear particles.(5) The "empty area" size is affected by the load and the speed. The higher the load is, the longer is the "empty area". The greater the speed, the longer the "empty area".