: Complex geological conditions such as widespread hard rock inclusions and nodules in deep coal seam mining lead to the engineering challenges of low rock-breaking efficiency and short cutter life. The root cause lies in the difficulty of predicting the heterogeneous mechanical response and multi-scale fracture behavior of coal seams containing nodules. To address this problem, we adopt the Smoothed Particle Hydrodynamics (SPH) method. As a meshless Lagrangian method, SPH combines the dual advantages of continuum modeling and large-deformation fracture analysis, avoiding the mesh distortion problem of the finite element method (FEM) and overcoming the limitation of the discrete element method (DEM) in restoring the stress-strain response of continuous media. Therefore, a numerical model of cutter penetration into rock strata is constructed, including a cutter-coal rock contact algorithm and a geotechnical elastoplastic constitutive model. A hybrid failure model combining the Drucker-Prager model and the Grady-Kipp model is introduced to describe the shear failure and tensile fracture behavior of hard coal rock, thereby establishing a dynamic fracture failure criterion for coal rock. The model is used to study the dynamic fracture evolution process of coal rock containing hard nodules (pyrite) under different cutter spacings (80–120 mm), cutter width (40–80 mm), and penetration velocities (1.0–2.0 m/s). The results show that nodules significantly alter crack propagation paths, causing main cracks to branch around nodules, with their size and distribution directly affecting the morphology of the fracture zone. The optimal synergistic effect is achieved at a cutter spacing of 100 mm (s/d≈1.67), with the lowest specific energy consumption (SEC) of 5.92 J/mm 3 , representing reductions of 75.2% and 58.6% compared to the 80 mm and 120 mm conditions, respectively. A cutter width of 60 mm yields the largest fragmentation volume (304,000 mm 3 ) and the lowest SEC (5.92 J/mm 3 ), which is 68.4% lower than that of the 40 mm width. The lowest SEC (4.51 J/mm 3 ) occurs at a penetration velocity of 1.0 m/s, while increasing the velocity to 2.0 m/s raises the SEC to 10.94 J/mm 3 . The research results provide theoretical and experimental bases for cutter parameter optimization and efficient rock-breaking processes.
Feng et al. (Fri,) studied this question.