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.

A large number of third bodies are born on the friction surface during braking. Exploring whether the third body has an impact on the friction surface temperature is helpful to recognize the wear factors affecting the brake disc. The effect of the third body composition on the temperature distribution of disc was studied by adding third body method on the TM-I inertial reduced scale brake testing machine, t Temperature distribution of the disc surface is compared at the pressure of 0.25 MPa and speed of 20-200 km/h under three conditions: no adding third body (NTB), adding Cu third body (CTB), and adding Fe third body (FTB). The results indicate that the difference in uidity and thermal conductivity between CTB and FTB leads to the deviation of the contact state of surface, thus forming the variation of temperature and distribution state of brake disc. At a speed of 120-200 km/h, when adding the CTB, the maximum temperature of disc surface is reduced by 1.9-3.1%, the proportion of the high-temperature zone is reduced by 4.3-13.1%, and the unit width temperature of the high-temperature area decreases 2.2-3.2%.When adding the FTB, the maximum temperature of the disc surface rises by 4.1-7.4%, meanwhile, the proportion of the high-temperature area and the temperature per unit width are increased by 1.4-5.4% and 5.9-20.2%, respectively. At high speeds, the good uidity and thermal conductivity of CTB lead to adhesive wear. FTB has high hardness, poor uidity and thermal conductivity, which causes oxidative fatigue wear.

A large number of third bodies are born on the friction surface during braking. Exploring whether the third body has an impact on the friction surface temperature is helpful to recognize the wear factors affecting the brake disc. The effect of the third body composition on the temperature distribution of disc was studied by adding third body method on the TM-I inertial reduced scale brake testing machine, t Temperature distribution of the disc surface is compared at the pressure of 0.25 MPa and speed of 20–200 km/h under three conditions: no adding third body (NTB), adding Cu third body (CTB), and adding Fe third body (FTB). The results indicate that the difference in fluidity and thermal conductivity between CTB and FTB leads to the deviation of the contact state of surface, thus forming the variation of temperature and distribution state of brake disc. At a speed of 120–200 km/h, when adding the CTB, the maximum temperature of disc surface is reduced by 1.9–3.1%, the proportion of the high-temperature zone is reduced by 4.3–13.1%, and the unit width temperature of the high-temperature area decreases 2.2–3.2%. When adding the FTB, the maximum temperature of the disc surface rises by 4.1–7.4%, meanwhile, the proportion of the high-temperature area and the temperature per unit width are increased by 1.4–5.4% and 5.9–20.2%, respectively. At high speeds, the good fluidity and thermal conductivity of CTB lead to adhesive wear. FTB has high hardness, poor fluidity and thermal conductivity, which causes oxidative fatigue wear.