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Simulation of rock-breaking process of polycrystalline diamond compact bit under circumferential impact torque

ABSTRACT. Stick-slip vibration is commonplace in the drilling of polycrystalline diamond compact (PDC) bit, which leads to early bit failure, low drilling efficiency and high drilling cost. Inspired by the application of torsional impactor, this paper establishes a nonlinear dynamic 3D numerical simulation model, in which the Drucker-Prager criterion is taken as the yield criterion of the rock. Then, the model was applied to simulate the dynamic rockbreaking process of the PDC bit under circumferential torque impactor. The results show that the stick-slip vibration was basically eliminated under the torque impactor, and the rate of penetration (ROP) increased by three times. This means the application of circumferential torque impactor to PDC bit can reduce the stick-slip vibration and enhance the ROP. The research findings provide a theoretical guidance on the application of torsional impactor on PDC bit.