Influence of Surface Treatments on Fretting Fatigue Life Prediction in TA15

Abstract

The objective of this work was to evaluate life prediction methodologies involving fretting fatigue of TA15 materials with advanced surface treatments. Fretting fatigue tests were performed on TA15 specimens with and without advanced surface treatments. Laser shock processing and low plasticity burnishing have been shown to produce deep compressive residual stresses with relatively little cold work. Testing showed these advanced surface treatments improved fretting fatigue strength by approximately 50 %. This work presents a mechanics based lifing analysis of these tests that takes into account the local plasticity and the redistribution of residual stresses due to the contact loading. The use of superposition of the residual stresses into the contact stress analysis results in unconservative crack growth life predictions. Finite element analyses were conducted to predict the redistribution of residual stresses due to the contact loading. The redistributed residual stresses were used to make improved crack growth life predictions when possible. The results showed very little redistribution of residual stresses for the advanced surface treatments.