Numerical Investigation of the Effect of Pre-induced Cracks on Hard Rock Cutting Using Finite Element Analysis

This paper presents a numerical investigation into the effects of pre-induced cracks on polycrystalline diamond compact (PDC) rock drilling processes under varying pressure conditions. A 3-D finite element model was created using a linear Drucker-Prager yield criterion in conjunction with a damage criterion to model element erosion. The model used a single PDC linear cutting configuration to highlight the differences between uncracked and cracked rock cutting in terms of cutting forces and cutting mechanism. The objective is to address the change in the effectiveness of pre-induced cracks under high-pressure conditions, similar to those in actual deep-drilling operations. The results show that the pre-induced cracks reduce the cutting force under the tested pressure range (0-100 MPa). The overall effectiveness decreases as the confining pressure increases because the pressure compacts the rock, restricting fracturing ahead of the cutter surface. Additionally, the rock cutting mechanism changes from a continuous removal of material at the atmosphere to a more intermittent form at higher pressures. Finite element simulations reveal the impact of confining pressure and pre-existing cracks on single cutter rock cutting dynamicsCalibration of granite rock behavior utilizing a pressure dependent Linear Drucker-Prager Yield criteriaIntegration of pre-existing cracks in the simulation through a node-separation algorithmAnalysis of the interaction between confining pressure and pre-existing cracks on rock cutting efficiencySimulation results showed changes in cutting mechanisms and force responses due to varying confining pressures and crack presence