Simulation-based Crack Growth Mitigation through Optimum Laser Peened Residual Stress Gulshan Singh 1,* , Juan Ocampo 2 , Harry Millwater 3 University of Texas at San Antonio, TX, 78249, USA Allan H. Clauer 4 LSP Technologies, Inc., Columbus, OH, 43016, USA Abstract Fatigue life of a component surface can be improved through inducing favorable residual stress at the desired location. Compressive stress on the surface tends to mitigate crack initiation and growth by negating the effect of tensile stress generated by loading conditions. Laser peening (LP) is a surface enhancement technique that can induce compressive residual stress on the surface. However, any residual stress surface enhancement technique generates tensile stress in addition to compressive stress for equilibrium. The tensile stress tends to be below and along the cir- cumference of the compressive stress region of the peened area. The location and magnitude of the tensile stress is critical because this stress can negate the benefits of LP. Therefore, LP parameters must be selected methodologically to ensure its benefits. To optimally design an LP process, an experimentally validated 3D finite element simulation of the LP process, a fatigue life estimation capability incorporating residual stress, and a particle swarm optimization strategy were developed and employed to maximize the fatigue life of a component of a turbine disk. The results achieved through proposed methodology indicate that a crack takes 13 times longer to * Corresponding author Email address: gulshan.singh@utsa.edu (Gulshan Singh) 1 Post-Doctoral Researcher. 2 Graduate Research Assistant. 3 Professor, Department of Mechanical Engineering. 4 Chief Metallurgist, LSP Technologies Incorporated. Preprint submitted to Journal of Materials Processing Technology April 23, 2011