Finite element modelling of 3D orthogonal cutting experimental tests with the Coupled Eulerian-Lagrangian (CEL) formulation

Most of the current finite element models of cutting concerns the 2D plane strain orthogonal cutting configuration, which, although of valuable interest to study the fundamental phenomena of the process, is still far from most practical cutting operations. The 3D models on the other side usually concern a 2D tool path with a cutting edge that is not straight any more. The step just after 2D orthogonal cutting is almost not addressed; it is the 3D orthogonal cutting. Based on an experimental reference of Ti6Al4V orthogonal cutting, this paper introduces a 3D finite element Coupled Eulerian-Lagrangian (CEL) model of orthogonal cutting that faithfully reproduces the experimental operation and is verified by comparison with it. Such a model and a comparison are not available in the current literature. A comparison is performed with a 2D orthogonal cutting model as well. The forces, the chip thickness and the lateral expansion of the chip were accurately modelled. The results showed that it is necessary to set the width of the workpiece large enough in order to get close to the plane strain assumption valid in the experimental configuration. A width of the workpiece equal to the uncut chip thickness constitutes a good compromise between the quality of the results and the number of nodes of the model. The Eulerian formalism of the workpiece mesh allowed to reduce its height and therefore the number of nodes without affecting the quality of the results. Moreover, this study showed that cubic elements should be adopted, as well as the addition of a range of elements that stays full of void and is parallel to the cutting plane at the boundary of the model to avoid influencing the results.