Effects of Friction Coefficient on Rolling Contact Fatigue Crack Initiation and Wear Growth

Abstract:

The modeling to discrete the continuous process of the coexistence of the fatigue crack initiation and wear growth was presented. Then, a threedimensional rail model for predicting the coexistence of the fatigue crack initiation and wear was established according to the theories of critical plane fatigue damage and Archard wear. The effects of different friction coefficients between wheel and rail contact positions on fatigue crack initiation and wear growth was analyzed. Results show that the friction coefficient has a great influence on the distribution of the adhesive and slip area, and the tangential stress in wheelrail contact patch, but has little effect on the size, shape and location of the contact patch. When the friction coefficient increased, the average wear growth rate and wear amount increased while the crack initiation life reduced. For example, with the increasing of the friction coefficient from 0.3 to 0.7, the average wear growth rate of the high and low rails increased about 17%~55% and 16%~42% respectively, and crack initiation life of them decreased about 24%~34% and 18%~35% respectively. The crack initiation position in the high rail was at about 2.0~2.5 mm below the rail surface and moved upward to 0.9~1.0 mm with the increasing of the friction coefficient. And the crack initiation position in the low rail kept at about 2.4~2.6 mm below the rail surface with the increasing of the friction coefficient. It can prolong the crack initiation life and reduce the wear of the curve rails to keep the friction coefficient at 0.3~0.4 between wheel and rail contact positions.

Key words:rail; rolling contact fatigue; crack; wear; friction coefficient