Research on the fretting contact fatigue strength of interference fit in high speed rail traction motor shafts

Abstract

Fretting wear and gear contact fatigue belong to adhesive wear. They have similar causes, failure mechanisms, and failure appearance. Drawing inspiration from the gear contact fatigue strength theory, this article creatively proposes a calculation method for the fretting contact fatigue strength. The safety factor of fretting fatigue is calculated to be 0.34. Due to the singularity of the contact point at the edge of the oil groove, the mesh size near this point needs to be sufficiently fine to 0.025 mm. The contact pressure at the edge contact point of the oil groove is calculated by finite element method (FEM) to be 1034 MPa, which is 6.8 times the Lame theoretical value of 152 MPa. The stress concentration is very severe. The fretting contact fatigue strength at the edge of the oil groove is severely insufficient. The friction torque of the interference connection is calculated to be 3.1 times the overload torque of the motor. The fundamental cause of fretting wear is excessive interference and unreasonable design.