Effect Mechanism of Water Jet Peening on Surface Integrity and Ultrahigh‐Cycle Fatigue Performance of “Sandwich” Laminates

ABSTRACT This study investigates the effect mechanism of water jet peening (WJP) on the surface integrity and fatigue performance of CoCrFeNiAl/Al6061 laminate composites. Through experiments and finite element simulations, the following results were obtained: At a jet velocity of 300 mm/s, significant plastic deformation was observed in the core layer, and the maximum residual compressive stress increased from 679 MPa at 250 mm/s to 802 MPa, indicating that higher jet velocity promotes the development of residual stress. Core layer thickness plays a crucial role in fatigue life; specimens with a 1‐mm‐thick core layer exhibited lower fatigue life, while a 2‐mm‐thick core layer showed significant improvement. The jet velocity of 300 mm/s was the most effective in enhancing fatigue life.