Abstract:The three-dimensional dynamic numerical model of PDC bit to break rock has been set up,in which the finite element models of rock,jet and mechanical tooth are created respectively based on elastoplastic mechanics,hydrodynamics and kinematics of rigid body. The interaction between jet or mechanical tooth and rock is simulated by dynamic contact method. The dynamic boundary is controlled by Hoffman failure rule. The single-step Houbolt algorithm is adopted to solve the dynamic equation. The rock-breaking mechanism has been analyzed comprehensively by various ways such as the interior stress distribution of rock,the weight on bit and torque of bit impacting rock,the volume of rock breaking,the energy of rock breaking,etc.. The influences of the number of blade and the position of high-pressure nozzle on bit breaking rock have been studied;and the structure of the dual-flow channel PDC bit has been optimized.