An experimental and numerical investigation on rock cutting behavior of specially-shaped PDC cutter

A theoretical model of ductile-brittle transition considering the cutter-rock friction was established, and the cutting force, mechanical specific energy (MSE), morphology of cutting chips and ductile-brittle failure transition mechanism of four different specially-shaped cutters were investigated through rock cutting tests. Furthermore, the 3D heterogeneous granite cutting numerical simulation models of 12 kinds of specially-shaped cutters and PDC bits were established by using the finite-discrete element method, and the problems such as the cutting force response, cutting chips formation, and MSE change rules were reproduced, as well as the influence of cutter shapes on drilling efficiency of PDC bits. The results indicate that there exists a critical cutting depth of ductile-brittle transition. Moreover, the critical cutting depth, MSE, footage and other parameters of 12 kinds of cutters were compared to provide a certain basis for the selection of drilling cutters, design optimization of drilling bits and the optimization of drilling parameters.