Experimental study on the effect of brake shoe pressure on wheel wear and fatigue damage behavior during tread braking

The widespread adoption of tread braking has made it necessary to study the wear and fatigue damage behavior of wheels under the combined action of brake shoes and rails. This study aims to investigate the influence of brake shoe pressure on wheel damage with an innovative small-scale test rig, the 'shoe-wheel-rail contact machine'. Two contact modes were designed: shoe-wheel contact and shoe-wheel-rail contact. The results indicated that, with the increase in brake shoe pressure, both the wear loss of the wheel and braking temperature increased significantly. However, compared to the shoe-wheel contact, the wheel wear and fatigue damage were more severe after the shoe-wheel-rail contact, and they were more sensitive to changes in the brake shoe pressure. Notably, under the shoe-wheel-rail contact, wheel fatigue damage was dominated by sub-surface cracks, whereas almost no fatigue cracks were observed under the shoe-wheel contact. Furthermore, when the braking temperature reaches 350 degrees C, the synergistic effect of the braking temperature and the plastic deformation caused by wheel-rail rolling contact induced the refinement of the microstructure of the wheel material.