Experimental Study on Initiation of Surface Fatigue Crack of Wheel Material under Dry Condition

The factors affected the initiation and propagation of surface fatigue crack of wheel under dry conditions were investigated and the formation mechanism and evolvement law of surface fatigue damage of wheel were analyzed using a WR-1 wheel/rail rolling wear testing apparatus, combined with the shakedown theory. The results show that with the increase of the vertical force, lateral force and attack angle, initiation and propagation of surface fatigue crack of wheel became more easily. Attack angle played an important role on the initiation and propagation of surface fatigue crack of wheel. Macroscopic oblique surface fatigue crack initiated and propagated obviously under the high attack angle conditions. Surface fatigue damage of wheel was not found in case of only the lateral force but no attack angle. Under cyclic periodic load, plastic flow was observed first on the surface of wheel. And then, propagation to oblique surface fatigue crack along the direction of the shear force on wheel/rail surface was observed. The vertical force was one of the important factors affecting the time of crack initiation.