Fatigue Crack Growth in Laser Shock Peened Thin Metallic Panels

Flat thin aluminum panels with centered crack have been Laser Shock Peened along straight patterns perpendicular to the crack. Despite of the locally induced compressive residual stresses, the experimental tests showed the negative effect of the LSP on the fatigue crack propagation performances of panels. Starting from the numerical assessment of the self-balancing residual stress distribution along the entire panel width, the fatigue crack growth through the panels has been analytically evaluated and compared with experimental results, showing a good agreement. The comparison highlights the sensitivity of the fatigue crack propagation life to the selected LSP pattern configuration (i.e. the width of the LSP treated strip and the relative position to the crack centre) which have to be accurately setup in order to exploit the full potentiality of the LSP process in increasing the fatigue life and avoid undesired reduction of the component performances.