Residual life prediction for healing fatigue damaged copper film by laser shock peening

A healing method for fatigue damage was studied by laser shock peening (LSP) with excimer laser for polycrystalline copper film. It is found that work hardening due to LSP could be responsible for the improvement of residual fatigue lives for the damaged and undamaged specimens by LSP, and the hardening degree for the damaged specimen by LSP is obviously higher than that for the undamaged specimen by LSP. In this paper, two basic mechanisms were identified. One is the dissipated energy enhancement mechanism, which improves the fatigue life caused by laser shock stress, and the other is the healing mechanism, which leads to a further improvement. Based on the two mechanisms, a residual fatigue life prediction method is proposed by the view of energy consumption before and after LSP. The predicted lives by the proposed method agree well with the experimental results.