Understanding Chip Formation in Orthogonal Cutting of Aeronautical Thermoplastic CF/PEKK Composites Based on Finite Element Method

There has been an enormous increase in using of carbon fiber reinforced thermoplastic (CFRTP) especially carbon fiber reinforce polyetherketoneketone (CF/PEKK) in automotive and aeronautical industries. However, fundamental material removal mechanism of such material has never been elucidated in the literature. In this work, finite-element (FE) method is deployed and microscale numerical model considering fiber, matrix and interface has been established to understand the mechanisms of chip formation in orthogonal cutting of unidirectional (UD) thermoplastic CF/PEKK composites. Chip formation and subsequent surface / subsurface damage with different fiber orientations (0°, 45°, 90°, 135°) are modelled and compared. Results suggest that, for CF/PEKK, the chip formation mechanism is significantly affected by the fiber orientation and the most severe subsurface damage can be seen at fiber orientation 135°, as a result of bending fracture below the ideal machined surface.