The effect of laser power density on the fatigue life of laser-shock-peened 7050 aluminium alloy

Laser shock peening (LSP) is an innovative surface treatment method that can result in significant improvement in the fatigue life of many metallic components. The process produces very little or no surface profile modification while producing a considerably deeper compressive residual stress layer than traditional shot peening operations. The work discussed here was designed to: (a) quantify the fatigue life improvement achieved by LSP in a typical high strength aircraft aluminium alloy and (b) identify any technological risks associated with its use. It is shown that when LSP conditions are optimal for the material and specimen configuration, a —three to four times increase in fatigue life over the as-machined specimens could be achieved for a representative fighter aircraft loading spectrum when applied at a representative load level. However, if the process parameters are not optimal for the material investigated here, fatigue lives of LSP treated specimens may be reduced instead of increased due to the occurrence of internal cracking. This paper details the effect of laser power density on fatigue life of 7050-T7451 aluminium alloy by experimental and numerical analysis.