Material removal and damage formation mechanisms induced by periodic indentation during ultrasonic vibration-assisted scratching of SiCf/SiC composites

Abstract

Fiber-reinforced ceramic matrix composites (CMCs) exhibit high hardness, brittleness, heterogeneity, and anisotropy. This study explores the material removal and damage formation mechanisms during ultrasonic vibration-assisted scratching of SiCf/SiC composites through experimental and micro-finite element simulations. The research reveals that high-frequency periodic indentation-separation of abrasive grain influences stress transfer and crack propagation, which are affected by the interfacial layer and fiber orientation. Crack deflection plays a crucial role in material removal and determines the amplitude of normal scratching force. Stress transfer interference primarily governs damage formation, with more severe damage occurring along the longitudinal and transverse fiber directions due to secondary stress concentration and crack deflection. In contrast, scratching along the perpendicular fiber direction requires higher normal forces due to residual adjacent phase materials, but results in more controlled material removal and less damage. The study provides insights into optimizing the ultrasonic vibration-assisted machining of CMCs to minimize damage.