Study On Numerical Simulation Method Of PDC Full Bit Breaking Rock

The numerical simulation technology of PDC bit has been widely developed, but for the limitations of experiment conditions and computer power,the literatures about the whole bits experiment、numerical simulation and analysis of load have not been found. On the one hand, this paper made a comparative research for numerical simulation of the finite element model, constitutive model, the accuracy of rock breaking simulation results both of PDC cutter and bits and try to find the different modeling methods’ effect on numerical simulation efficiency. On the other hand., through the finite element method,the author get the stresses on main PDC cutters during the process of rock breaking, and make a prediction about the wearing trend of PDC cutting teeth.Firstly, on the basis of Mohr-Coulomb model and Drucker-Prager model, a finite element model was established by ABAQUS, which used to research the load of PDC single cutter-rock interaction that under different cutting parameters. The Comparison between simulation and experimental results shows that the deviation of the Mohr-Coulomb model on the resulting slightly larger than the Drucker Prager model. But its computational efficiency is3.1times of the latter. And it is more suitable for numerical simulation of PDC bits drilling rock.Then, based on the numerical simulation of PDC cutters, the author established the numerical simulation of PDC single wing cutter breaking rock. The analysis results shows that the torque on cutters which near to the PDC center is smaller than others. While, the torque on cutters at the top is the biggest. Based on the above study, we established the numerical simulation model of the whole PDC bit. The author made a comparison of the PDC bits experiment and numerical simulation, the results shows that the deviation of axial pressure and torque is lower than6.5%and8.2%in the numerical simulation respectively, and the fluctuation of dynamic load nears to each other in the two situation.Finally, based on the numerical simulation of PDC bits,the author analyzed the forces on cutters,including tangential force, radial force and axial force and evaluated the wearing trends of PDC bits.The performances of bits suggest that the wearing trend is in accordance with the actual phenomenon.The experiments of PDC cutter and bits illustrate that this numerical simulation method can be also used to research the load on cutter and the development of PDC bits.