Thermo-mechanical Coupling Numerical Analysis Of The Temperature Field Of PTFE-based Composites During Friction

Polytetrafluoroethylene (PTFE) is a self-lubricating material with excellent comprehensive performance, widely used in frictional parts. Because a lot of friction heat will generate during friction and PTFE is very sensitive to the friction heat, the tribological properties of PTFE greatly depend on temperatures. To improve its tribological characteristics, it is of great significance to study PTFE composite frictional temperature field and its relations to the composite compositions and thermal characteristics. In view of this, the PTFE composites were chosen as the research object in this thesis, the thermal characteristics of the composite materials were enhanced by changing the copper content in the matrix, the frictional temperature field of PTFE composites was analyzed by using Thermo-Mechanical Coupling Numerical Analysis method, the change of the sample temperatures during friction was online recorded by the thermocouples and an infrared thermal imager.The Thermo-Mechanical Coupling effect was considered during frictional temperature field numerical analysis of PTFE-based composites. Three factors, namely copper content, pressure and speed, were considered to study their influence on the thermal properties of the composites. The frictional temperature field distributions and variation rules were analyzed based on the simulation results. The results showed that the more the copper content, the higher the thermal conductivity of PTFE composites is, the faster the temperature of the composites rises during friction, the smaller the temperature gradient between the upper and lower surfaces of the samples is. With the increase of copper content, the friction coefficient of PTFE-based composites decreases, the wear volume also shows a decreasing trend. The greater the pressure and/or speed, the faster the spread of friction heat to the inner of the material is, the faster the temperature rises, the smaller the temperature difference between the upper and lower surfaces of the samples is. In addition, the sliding friction coefficient decreases with the increase of the pressure, and increases with the increase of the sliding speed.Meanwhile, the frictional temperature measurements PTFE-based composites filled with copper particles were carried out on a multi-functional and environmental controllable tribometer. In our work, the lower samples were made of PTFE composites filled with copper and the upper samples were made of 45 steel. The contact mode is surface contact during friction. The effects of copper content, pressure and speed on the test results are also considered. The infrared thermal imager and thermocouple were used for frictional temperature measurement of PTFE-based composites. To verify the accuracy of simulated results, the test and simulation results were compared and analyzed. The comparison shows that the trends of the temperature curves of simulated and recorded results are consistent. The analysis shows that there is a linear relationship of temperature difference between simulated results and experimental results, which can be expressed by regression formulae. Furthermore, as compared with the thermocouple results, the simulation results are higher; while the infrared recorded results and simulation results are close. Considering the high accuracy of infrared recorded results, the simulation results can be regarded as reasonable and accuracy results.