A bending vibration-assisted ultrasonic surface rolling method for load-bearing holes

Crack initiation on the wall surfaces of load-bearing holes is primarily attributed to surface irregularities and non-uniform residual stresses caused by machining. This study introduces a novel ultrasonic surface rolling method based on bending vibration (USR-BV), which is specifically developed to enhance the surface integrity and fatigue performance of load-bearing holes. The USR-BV system was modeled and optimized using finite element analysis to allow the application of ultrasonic vibrations perpendicular to the surface. Experiments on 7050-T7451 aluminum alloy at various penetration depths showed notable improvements in surface roughness, residual stress, and fatigue life. A depth of 0.08 mm yielded optimal results, increasing fatigue life by 93 %. The proposed USR-BV technique highlights a unique contribution by providing an effective and scalable approach to treating load-bearing holes across a wide range of diameters using a single setup, thereby addressing a critical gap in current fatigue enhancement technologies.