Analytical modelling of rock cutting force and failure surface in linear cutting test by single PDC cutter

The PDC (Polycrystalline Diamond Compact) bits are the most widely used bits in oil drilling engineering, in order to further improve their longevity and ROP (Rate of Penetration), single PDC cutter research is very important. However, previous work focused mostly on experiment and numerical simulation while analytical modelling still lacks progress. In this paper, a new analytical model of rock cutting force and failure surface is proposed based on the stress state calculation of each micro-unit inside the rock. The cutting force predicted by this model is well verified by experiments under different parameters like depth of cut, back rack angle, rock type, cutter size and confining pressure. It is also found that the shape of failure surface is a curved line rather than straight, and long and thin cuttings will be formed. Finally, on the basis of this model, the influence mechanism of each parameter on cutting force and the shape of failure surface are analyzed. The method and result of this study are expected to provide a better understanding of cutting force and rock breaking mechanism by PDC bits.