Parametric analyses of thermoelastic instability in disc brakes

Abstract

Thermoelastic instability (TEI) results in uneven heating of the rotor and the development of hot spots in automotive disk brake systems. The hot spots cause rotor distortion and thickness variation which can cause torque variation resulting in brake roughness and low frequency noise. An analytic study has been performed using the basic equations developed by Lee and Barber (1993) extended to include the pad thickness (Hartsock and Fash, 1999) and partial rotor surface contact with the pad (Lee and Barber, 1995; Ayala et al., 1996). Relevant pad and rotor material properties as well as the pad thickness, rotor thickness and coefficient of friction were varied by a fixed percentage to determine the effect on the critical speed for TEI. The relative importance of each parameter was established and the predicted direction of change to increase the critical speed was identified.