Effect of Material Properties and Structure of Frictional Pad on Thermoelastic Instability of Disc Brake

Abstract:

A mathematical model on thermoelastic instability (TEI) of two dimensional disc brake was built. Change rules of critical speed, growth rate of perturbation and its migration velocity in metal disk and frictional pad were respectively resolved by utilizing perturbation method with the assumption that hot spots were antisymmetrically distributed on frictional surfaces. Then, the effects of frictional pad’s thickness, material properties and finite contact length on critical speed were analyzed and compared. The results show that, critical speed will decrease firstly and then grow again with wave number and there is an opposite trend of migration velocity in brake disk and frictional pad. Meanwhile, it is almost zero in metal disk with higher thermal conductivity. The stability of sliding frictional system can be enhanced by increasing the thickness, thermal conductivity and specific heat of the frictional pad.

Key words:disc brake; thermoelastic instability(TEI); growth rate of perturbation; critical speed; wave number