Effect of Geometry on Thermoelastic Instability in Disk Brakes and Clutches

Abstract

The finite element method is used to reduce the problem of thermoelastic instability (TEI) Introduction The frictional heat generated during sliding causes thermoelastic expansion that affects the distribution of contact pressure. The resulting thermomechanical feedback is unstable if the sliding speed is sufficiently high, leading to the development of non-uniform contact pressure and local high temperatures known as "hot spots." This non-uniformity also tends to cause a low frequency vibration known in the automotive disk brake community as "hot roughness" or "hot judder." This is a significant source of customer warranty claims and has resulted in an increased interest in the subject in recent years The mechanism of thermoelastic instability or "TEI" was first explained by These idealized treatments provide a useful indication of the nature of the phenomenon and the effect of material properties on the critical speed, but the predicted critical speeds are typically significantly higher than those observed experimentally. A significant step towards explaining this discrepancy was made b