Research on the type and expansion mechanism of internal cracks in rocks under the action of PDC.

The rock fragmentation mechanism of polycrystalline diamond compact (PDC) constitutes a fundamental research focus in petroleum and mining engineering. This study presents an experimental investigation into crack propagation failure characteristics during cutter-rock interaction. Through an integrated experimental approach combining mechanical testing with digital image correlation (DIC) monitoring, the complete failure process from microcrack initiation to macroscopic fracture network development was quantitatively characterized. Experimental observations demonstrate significant dependence of crack propagation patterns on PDC cutter geometry, particularly the back rake angle. Initial fracture development (Stage I) exhibits predominant shear failure mechanisms, with tensile crack formation becoming progressively dominant during sustained loading (Stage II). The DIC-derived Displacement Field analysis revealed three distinct crack interaction modes: parallel propagation, bifurcation merging, and hierarchical networking. These findings provide a solid theoretical foundation for further research on PDC rock-breaking mechanisms, contributing to the optimization of drilling operations in engineering applications.