Pre-loading enhancement of compressive residual stress at crack-tip in acoustic cavitation

We propose to combine the crack tip stress field with acoustic cavitation to generate compressive residual stress at the crack tip in the bulk metal which is challenging to access. The sharply increasing stress profile (stress singularity) at the crack tip offers to amplify plastic deformation induced by the local impacts (shockwave/microjet) from the acoustic cavitation introduced to the crack tip, which then enhances the compressive residual stress generation at the crack tip. The effect of the crack tip stress field on compressive residual stress generation was experimentally investigated for crack depths of 10 and 20 mm. The experiments prove that the crack tip stress field increases the acoustic cavitation-based compressive residual stress by up to three times. Also, the stress intensity factor of the crack tip stress field was found suitable to represent the engagement of the crack tip stress field with the cavitation-based compressive residual generation.