Mechanism and Conditions of the Polygonal Wear of Vehicle Tire

Polygonal wear seriously decreases the lifespan of a tire of a passenger car and adversely affects vehicle dynamic safety. The present paper builds a model that reflects the dynamic contact characteristics of the tire and reveals the mechanism and conditions of polygonal wear of a tire. The model describes the dynamic contact behavior of the tread block and considers the characteristics of dynamic friction between the road and tread of a rolling tire. Conducting numerical bifurcation analysis, the paper reveals the conditions for self-excited vibration of the tread, i.e., the improper combination of the vertical load, wheel slip angle, tire pressure and vehicle speed considerably strengthen the lateral self-excited vibration of the tread, which is the direct vibrational source of abnormal circumferential polygonal wear. The polygonal wear of a tire occurs when a vehicle travels for a certain long distance at a so-called polygonal wear speed. The polygonal wear speed should induce lateral self-excited vibration on the contact tread of the tire and the frequency of the lateral self-excited vibration should be divisible by the rolling frequency of tire that is determined by the polygonal wear speed. Visible polygonal wear requires that the vehicle travels at a certain polygonal wear speed for a minimal distance to produce a stably developing polygonal wear pattern even for subsequent driving at variable speed. © 2018, Society of Automotive Engineers of China (SAE-China).