Investigation on Effect of Torque on Fretting Damage of Test Facility Shaft

The effect of torque on the fretting damage of an interface fit between the shaft and inner surface of bearings was investigated on the JD-1 wheel/rail simulation test facility with different loads. The fretting damage mechanism of the shaft surface was analyzed by observing the wear scar and microstructure of the cross-section of specimens by using a laser scanning confocal microscope and scanning electronic microscopy. The results indicate that the fretting damage appears on the interface fit between the shaft and inner surface of bearings under vertical load and braking torque, the wear is in the form of adhesive wear and abrasive wear. With an increase in braking torque, the wear on the surfaces of shaft is more serious, the plastic deformation layer is thicker by approximately 75%, the fretting damage becomes more severe. Moreover, the wear and plastic deformation on the left surface are more severe than those on the right, and the plastic layer is uneven. Micro cracks appear on the interface fit, and there are more cracks on the left interface fit than those on the right, the number of micro cracks increase by approximately six times with the increase of the braking torque, and the crack propagation angle also increases by approximately 50%.