A numerical study of disc brake wear dependence of rotor surface parameters

Airborne emissions from disc brakes adversely affect the air quality in urban areas of EU. The emissions come from the wear of the pads and rotors in disc brakes. The wear of disc brakes depends on the contact situation between the pads and rotors. During braking, secondary contact plateaus are created on both the pads and rotors contact surfaces. Literature reports numerical studies of the creation of contact plateaus on the pad surface but no numerical studies known to the authors have taken into consideration the creation of contact plateaus on the rotor surface. Furthermore, experimental studies reported in the literature shows that secondary plateaus are created in the low-lands of the rotor contact surface and that this affects the wear performance. In particular, it has been reported that the creation of secondary plateaus on coated rotors have a relatively large affect the wear and emissions. The aim of this study is therefore to numerically investigate how the creation of contact plateaus on the rotor surface could affect the disc brake wear performance. This is done by expanding an existing simulation tool used for simulation of friction, wear and particle emission, which takes into account the creation of contact plateaus on the pad surface, to include creation of contact plateaus on the rotor surface. One rotor surface that corresponds to a cast iron rotor is compared with one rotor surface that corresponds to a coated rotor. The results are qualitatively in line with observations done in pin-on-disc tribometer tests. It remains to validate the numerical results with data obtained in experiments.