Influence of contacting shape of partial wear on friction properties of copper-based materials for trains

In view of the fact that the contact between the pad and the disc cannot match perfectly in the actual braking process, the influence of contacting shape on the tribological performance was studied. Four copper-based brake pads in ratio (radial dimension / circumferential dimension) of 0.4, 0.6, 0.8 and 1.2 were used to perform contacting shape test on a small-scaled braking dynamometer at speeds 60 km/h, 100 km/h, 140 km/h and 180 km/h and contact pressure 0.5 MPa. The results indicated that contacting shape caused the difference of temperature of the brake system, which affected the friction performance. The peak temperature of the disc decreased from 331°C to 293.2°C with ratio increasing, and the maximum effective stress of the disc decreased 15%. In ratio of 0.4, the higher friction temperature and effective stress made the friction surface easy to plough, so the friction coefficient was low and the wear was nonuniform. In ratio of 1.2, the wear particles accumulated, resulting in high friction coefficient and uniform wear.