Comparison of different theoretical models for flash temperature calculation under fretting conditions

The wear and friction properties of tribological interfaces depend significantly on the contact temperature, and its determination is therefore important for each tribological application. Temperature calculation methods available in the literature use quite different physical, dynamic and geometrical assumptions. Furthermore, the assumptions necessary for temperature calculations also include various interfacial properties, which are usually unknown due to many difficulties in their exact determination. It is therefore important to know the possible differences between several frequently used models for flash temperature calculation and also the effect of these pre-assumed input parameters. In the present work the effects of the tribological interface between silicon nitride and steel under dry and boundary lubricated fretting conditions were studied. Effects of the change of thermal properties, as well as the coefficient of friction and the real contact area on the calculated flash temperature are presented. Ten different theoretical models were selected for the purposes of this investigation. The results show crucial differences between the various models and the significant importance of the tribological interface properties on the calculated temperatures. Based on these calculations, supported by experimental evidence, it is clear that their severe limitations must be considered and care in the interpretation of the results taken when such models are used.