Rotary ultrasonic rolling chamfer: impact on surface integrity and fatigue performance of load-bearing holes

Abstract

Fatigue failure of load-bearing holes under high-frequency cyclic loading remains a critical challenge in mechanical systems due to geometric stress concentration. This study proposes a novel rotary ultrasonic rolling chamfer (RURC) process to improve the fatigue performance of load-bearing holes. A simulation model, developed based on the kinematic and force analysis of the RURC process, was employed to predict residual stress distributions and optimize static force parameters. Finally, fatigue experiments were conducted to assess the effectiveness of the RURC process. The simulation results of surface residual stress showed good agreement with experimental data, with a maximum deviation of 7.9 %. An appropriate increase in static force can effectively enhance the compressive residual stress at the chamfer surface, although it may also intensify local stress concentration. The RURC process significantly improves fatigue resistance by inducing beneficial compressive residual stress, refining the grain structure, increasing microhardness, and reducing surface roughness, with residual stress playing a critical role. Under optimized conditions (375 N static force), a surface compressive residual stress of 250 MPa was achieved. Fatigue life increased by 57 % under a maximum cyclic stress of 340 MPa and by 107 % under 220 MPa. These findings demonstrate that the RURC process has strong potential as an effective method for further enhancing fatigue performance in load-bearing holes.