Analysis of Grinding Mechanics and Improved Force Model in Ultrasonic Assisted Grinding Cf/SiC Composites

Grinding is a key precision machining method for achieving high surface quality and dimensional accuracy in carbon fiber reinforced silicon carbide ceramic matrix composites (Cf/SiC). Ultrasonic vibration-assisted grinding (UVAG), with its high-frequency intermittent loading characteristics, offers a novel approach to regulating the dynamic removal behavior of heterogeneous materials. This study firstly analyzed the material removal mechanism of abrasive particles based on abrasive geometry and kinematics. On this basis, mechanical models are developed for a single abrasive grain across three removal stages: ductile removal, ductile-to-brittle transition, and brittle removal. These are further extended into a grinding force prediction model by integrating the effects of multiple abrasive grains and process correction factors during ultrasonic-assisted grinding. Finally, the model is validated through UVAG experiments. Results show that under an ultrasonic frequency of 20 kHz and amplitude of 5 μm, the predicted grinding forces match the experimental values with a high degree of accuracy (98.98%). This grinding force model provides theoretical support and process guidance for high-performance, low-damage precision machining of Cf/SiC composites.