Study on surface integrity and crack propagation mechanism of Ti/Al composite plates enhanced based on water jet peening

This study investigates the mechanisms through which water jet (WJ) enhancement affects surface integrity and crack propagation in Ti/Al composite plates. Finite element models for both WJ enhancement and crack propagation were developed using ABAQUS, complemented by experiments analyzing the influence of different jet velocities on surface integrity parameters, such as residual stress and surface roughness. These parameters were then examined for their effects on the stress intensity factor (SIF), fatigue crack propagation rate (FCP), and crack propagation path.The results demonstrated a positive relationship between jet velocity and both surface roughness and maximum residual compressive stress in specimens treated with WJ enhancement. Specifically, as jet velocity increased from 300 mm/s to 350 mm/s, surface roughness rose approximately 4.2-fold to around 0.95813 μm, while maximum residual compressive stress increased from 1109.9 MPa to 1472.5 MPa. The uniform distribution of residual compressive stress contributed significantly to the reduction in the stress intensity factor.Additionally, the crack propagation rate was inversely correlated with jet velocity. The residual compressive stress induced by higher jet velocities effectively slowed crack propagation. The theoretical interpretation of residual compressive stress as an equivalent damping layer further validated the effectiveness of WJ enhancement in reducing crack propagation in Ti/Al composites.