The effect of surface roughness on the temperature at the contact between sliding bodies

Although a great deal of work has been carried out in recent years on the temperature rise at the contact between rough rubbing bodies due to its significance in the friction and wear behaviour of sliding bodies, a clear correlation between the contact temperature rise and the surface topographic parameters is lacking. The paper describes experiments to measure these temperatures using an infrared thermal imaging technique with a systematic variation in surface roughness. The surface temperature is seen to increase monotonically with roughness. The existence of two levels of contact temperature rise, as reported by other authors, is also observed in the thermal images. A theoretical analysis of surface temperatures on multi-asperity consideration has also been presented. It is found that two newly-defined non-dimensional parameters, termed elastic and plastic load indices, in terms of applied load and roughness parameters, describe the extent of roughness effect on the contact temperatures. For different speed and deformation conditions there exist critical values of these indices at which the surface roughness effects become insignificant. A good correlation between the theoretical proposition and experimental result was observed.