Finite element analysis of surface milling of carbon fiber-reinforced composites

Despite increased applications of carbon fiber-reinforced plastic (CFRP) materials in many industries, such as aerospace, their machining is still a challenge due to their heterogeneity and anisotropic nature. In this research, a finite element model is used to investigate the cutting forces, chip formation mechanism, and machining damage present during the flat end milling of unidirectional CFRP. The material is modeled as an equivalent orthotropic homogeneous material, and Hashin's theory is used to characterize failure in plane stress conditions. The friction coefficient between the tool and the composite material was assumed to be dependent on the carbon fiber orientation. A comparison of modeling and experimental results indicates that the model successfully predicts the cutting forces. The numerical model predictions of machining damage around the cutting area due to fiber compression damage and matrix cracking and the relation between damage extension and fiber orientation are confirmed through a comparison with SEM images of machined edges and surfaces.