Meso-scale fracture behavior and damage suppression mechanism of resin mineral composites in ultrasonic vibration-assisted grinding

Resin mineral composite (RMC) has become a novel structural material with great development potential in the field of high-end precision equipment, owing to its excellent properties including high damping capacity, low thermal expansion coefficient, and corrosion resistance. However, its inherent multiphase heterogeneous characteristics and brittle-viscoelastic hybrid properties lead to machining defects such as interface debonding, aggregate chipping, and subsurface cracks during the grinding process, bringing great challenges to precision low-damage machining. In this research, two types of RMC specimens, namely granite-filled RMC and quartzite-filled RMC, were designed and fabricated. The micromechanical properties of the mineral phase region, composite region, and two-phase interface region of the materials were accurately characterized via nanoindentation tests. A discrete element method (DEM) model of RMC grinding considering irregular breakable aggregates was established to reveal the meso-scale damage evolution law of the material under conventional grinding and ultrasonic vibration-assisted grinding (UVAG), as well as the defect suppression mechanism of ultrasonic vibration. Combined with systematic grinding experiments, the evolution characteristics of grinding force and the machining stability boundary were analyzed. The results show that the mechanical property mismatch between the mineral phase region and the composite region of quartzite-filled RMC is higher than that of granite-filled RMC, resulting in stronger interface defect sensitivity and worse machinability. UVAG can reduce the peak grinding force by 10%∼30% and the maximum crack propagation depth by more than 50%. It significantly suppresses interface debonding and subsurface damage, and effectively widens the stable machining process window of the material.