Study on nucleating location and formation of fretting fatigue cracks

The influence of different geometry shapes of fretting-bridge foot (r = 0 mm for rectangular and r = 0.3 mm, 0.6 mm, 0.9 mm) on the distribution of contact stresses was mainly investigated. Using the different values of r to simulate the wear of the fretting-bridge foot, the distribution of contact stresses and the zone with wearing, sticking, sliding and opening on contact surface were calculated in details using finite element program ANSYS. After analyzing the nucleating locations of cracks, the relationship of different values of r, which represented wear, and nucleating locations of crack were established. For the contact geometry of a specimen contacting with a rectangular fretting bridge, the influence of distribution of nominal contact pressure on stresses of contact surface was also calculated. A three dimensional finite element method was used to analyze the contact stress distribution of a specimen contacting with a rectangular fretting bridge. The results show that several cracks usually nucleated simultaneously on the contact surface. The analysis results were in good agreement with the experimental ones.