Finite Element Modeling of Orthogonal Cutting of Pyrolytic Carbon

Abstract

Engineered features on pyrolytic carbon (PyC) have been demonstrated as an approach to improve the flow hemodynamics of the cardiovascular implants. In addition, it also finds application in thermonuclear components. These micro/meso scale engineered features are required to be machined onto the PyC leaflet. However, being a layered anisotropic material and brittle in nature, its machining characteristics differ from plastically deformable isotropic materials. Consequently, this study is aimed at creating a finite element model to understand the mechanics of material removal in the plane of transverse isotropy (horizontally stacked laminae) of PyC. A layered model approach has been used to capture the interlaminar shearing and brittle fracture during machining. A cohesive element layer has been used between the chip layer and the machined surface layer. The chip layer and workpiece are connected through a cohesive layer. The model predicts cutting forces and the chip length for different cutting conditions. The orthogonal cutting model has been validated against experimental data for different cutting conditions for cutting and thrust forces. Parametric studies have also been performed to understand effect of machining parameters on machining responses. This model also predicts chip lengths which have also been compared with the actual chip morphology obtained from microgrooving experiments. The prediction errors for cutting force and chip length are within 20% and 33%, respectively.