Study on scratch hardness in ultrasonic vibration-assisted scratching based on instantaneous contact analysis

The limited knowledge of scratch hardness in ultrasonic vibration-assisted scratch (UVAS) impedes a comprehensive understanding of the abrasive wear process with ultrasonic vibration. The main challenge is the complex kinematic-geometric characteristic of instantaneous contact induced by ultrasonic vibration and the abrasive particle. This paper proposed a novel method to describe the contact behavior exerted by ultrasonic vibration in multiple directions. The wear behavior of the indenter in the UVAS test was analyzed, and the indenter surface was measured to calculate the instantaneous contact area. Based on the developed model and the UVAS test, the effects of ultrasonic vibration on scratch hardness with varying scratch velocity and cutting depth are evaluated. It could be found that the scratch hardness for UVAS was reduced compared to that of common scratch owing to the changed contact states. This study provides an effective tool to capture the instantaneous contact state with a complex moving path and predicts the scratch hardness under ultrasonic vibration through common scratch tests.