3D Continuum Modelling of PDC Cutting of Rock with a Simple Contact-Erosion Scheme

Abstract

Featured Application: The numerical method presented in this paper is designed to estimate the cutting force and the removed material volume during rotary rock drilling by a single PDC cutter. This paper presents a relatively simple numerical approach to predict the cutting force during PDC (polycrystalline diamond contact) cutting of rock. The rock failure model is based on a damage-viscoplasticity model, with the Drucker–Prager yield surface and the modified Rankine surface as the tensile cut-off. The damage part of the model has separate scalar damage variables for tension and compression. The PDC cutter is idealized to a rigid surface and its interaction with the rock is modelled by contact mechanics, while solving the global equations of motion explicitly in time. A damage-based erosion criterion is applied, to remove the contact nodes surrounded by heavily damaged elements. The eroded elements are left in the mesh as ghost elements that do not contribute to the load transfer but preserve the mass conservation. Numerical simulations on granite, demonstrate that the method reliably predicts the cutting force of a single PDC cutter at different cutting depths and rake angles.