A cutting force prediction model for rotary ultrasonic side grinding of CFRP composites considering coexistence of brittleness and ductility

Cutting force has a great effect on the machining surface/subsurface damage. The prediction model of cutting force is necessary to optimize input variables. During rotary ultrasonic side grinding (RUSG), the indentation depth of a single abrasive grain increases (up milling) from 0 to maximum or decreases (down milling) from maximum to 0 with the motion of abrasive grains. Therefore, the ductile removal mode and brittle fracture removal mode coexist. In this research, a mechanistic cutting force model in RUSG of carbon fiber–reinforced polymer (CFRP) composites, considering both brittleness and ductility, has been developed for the first time. The ductile-brittle ratio K has been put forward and obtained through experiments. The cutting force perpendicular to feed direction has been calculated by integration method from the point of force analysis. The results showed that K increases with the rise of spindle speed or the decrease of feed rate and cutting width. The cutting force behaves oppositely with respect to K . Finally, orthogonal experiments have been conducted to verify the cutting force model and the results show good consistency between theoretical cutting force and measured cutting force. The developed model is capable to predict the cutting force in RUSG of CFRP composites and provides a support for optimizing the process.