Simulation-based evaluation of surface micro-cracks and fracture toughness in high-speed grinding of silicon carbide ceramics

Surface/subsurface crack during grinding limits the application of engineering ceramics. High-speed grinding is proposed in ceramics grinding for high material removal rate and surface quality. The dynamic fracture toughness of ceramic materials is established by combining the Johnson-Holmquist 2 damage model for brittle material and the Griffith fracture theory. Single-grit simulation was utilized to investigate the individual crack generation and propagation in silicon carbide (SiC) indentation and engagement under different wheel surface speed. The indentation simulation results indicate that high-speed grinding enhances the SiC plastic deformation in the contact zone. Engagement simulation shows that the micro-crack transforms from deep and narrow longitudinal crack in the subsurface to shallow and width lateral crack on the surface when the wheel surface speed increases with a constant maximum undeformed chip thickness. To validate this model, the high-speed grinding experiments are conducted. The trends of micro-crack evolution, single grit force, and surface roughness of the experimental results at the constant workpiece feed rate match well with the simulation results.