Effects of vibration amplitude on subsurface damage of SiC in rotary ultrasonic grinding

Rotary ultrasonic grinding (RUG) exhibits significant advantages in the machining of hard and brittle materials, such as silicon carbide (SiC), an important engineering material. However, the ultrasonic excitation mechanisms remain unclear, unfavorable to promote machining efficiency and surface quality. A notable pending problem is the inconsistency of ultrasonic vibration amplitude on subsurface damage in a workpiece. To address this, a simulation model was developed in this study to analyze the formation of subsurface damage, and corresponding experimental RUG of SiC were conducted for the verification. Four evaluation indexes - average chipping depth, maximum chipping depth, average crack depth, and maximum crack depth - were employed to characterize the subsurface damage. Simulation results revealed that the maximum crack depth decreases initially and then increases as ultrasonic vibration amplitude increases. These trends were corroborated by experimental findings. Furthermore, both the kinematics and dynamic behavior of abrasive grains on grinding tool were comprehensively analyzed based on the indentation fracture mechanics model. Theoretical analysis of variation trends provided further insights into the effects of ultrasonic vibration, elucidating the factors responsible for the inconsistencies between ultrasonic vibration amplitude and subsurface damage.