Study of friction, wear and plastic deformation of automotive brake disc subjected to thermo-mechanical fatigue

Abstract

The function of the automotive braking system is to reduce the vehicle’s speed or stop within a stipulated time. An efficient braking system dissipates all heat generated during braking into the environment before subsequent braking is applied. The heating and cooling cycles, in combination with mechanical loads during braking operation, cause thermal stresses on the surface of the brake disc. The resulting thermomechanical fatigue (TMF) on the brake disc is a life-limiting factor and causes failure. Understanding their impact, given experimental investigation using a full-scale inertia brake dynamometer is the paramount aspect. The reference disc, that is used for the experiment is a wheel-mounted brake disc. During the investigation, it is observed that (i) friction coefficient is sensitive to vehicle speed and braking pressure (ii) fade test records a maximum brake disc temperature of 403°C (iii) repeated thermal and mechanical cycles induced plastic deformation and cracks on the brake disc. The study provides insight into the parameters contributing to the damage at the friction surface of the brake disc that is subjected to Thermo Mechanical Fatigue (TMF).