The influence of spot overlap and laser flence on the high cycle fatigue (HCF) strength of aircraft engine fan blades

One way to measure the benefit of Laser Shock Peening (LSP) is to perform high cycle fatigue (HCF) testing of engine components that have undergone LSP. In a production environment, there is an additional constraint that the LSP process must prove itself stable over time. During development of LSP at GE, numerous studies were carried out to identify the factors that affect HCF strength. Based on these studies, six production processes have been introduced over the last seven years. In this article, a study of the influence of LSP spot overlap and laser fluence on HCF strength is presented. Finally, a geometric scaling parameter that relates HCF strength to spot overlap is proposed as a means of predicting HCF benefit for various engine components.