Chip Formation Mechanism in Machining of Carbon Fiber Reinforced Plastic

Abstract

Machining of carbon-fiber-reinforced plastic (CFRP) is still a challenging due to its inhomogeneous and anisotropic properties, which often lead to damage such as the delamination and the fiber pullout. The chip formation mechanism in machining of CFRP is completely different from the mechanism in metal cutting. In this paper, a two-dimensional macro equivalent homogeneous finite element model is established to simulate the dynamic cutting processes of unidirectional CFRP (UD-CFRP). The anisotropic material constitutive, the initial failure criterion and the damage evolution rule are defined in this model to investigate the material responses under the cutting load. Furthermore, the specific stiffness degradation variables are set to calculate the residual stiffness in cutting process. Failure mechanisms in chip formation in machining of CFRP for 0°, 45°, 90°and 135° fiber orientations are investigated by this model. And the effect of rake angle and the depth of cut on the chip formation are also analyzed. Cutting experiments of CFRP are obtained to observe the chipping process by microscopic observation accordingly. Finally, the chip formation mechanisms in machining of CFRP are summarized as the debonding-bending type and the cutting type. There is serious sub-surface damage in machining of CFRP for 135° fiber orientation.