Analytical model of grinding force for ultrasonic-assisted grinding of C_f/SiC composites

Ultrasonic-assisted machining of silicon carbide (SiC) ceramic matrix composites (CMCs) has the ability to decrease grinding force and improve processing quality. The machining process often produces large cutting forces which cause defects, such as delamination and burrs, due to the brittleness and high hardness of the material. Therefore, it is significant to precisely predict the grinding force. In published literature, the modelling of cutting force has been investigated based on brittle removal assumption. However, a ductile flow phenomenon exists simultaneously during the micro-grinding of CMCs. Hence, in this paper, we present an analytical model of grinding force with the consideration of ductile–brittle transition. Additionally, the critical cutting depth for removal mode transition can be applied to distinguish the ductile and brittle fracture removal processes. The establishment of the analytical model was on the basis of the research of single abrasive grain, including motion trajectory, micromechanical analysis, cutting time, and removal volume in ductile and brittle fracture processes during one cutting cycle. Thereafter, the final model was proposed with respect to the quantity of active abrasive grains in the cutting area. The trend of the experiment results was in good agreement with the predicted values of the analytical model.