黑料网

Abstract

A split Hopkinson bar was used to determine the fracture characteristics of coal samples with various bedding angles in order to explore the effects of bedding structure and various loading rates on the dynamic fracture characteristics and energy dissipation of Datong coal. The high-speed camera captured the crack start and propagation phase in Datong coal [1]. On the basis of the finite element method (FEM) and the J-integral, the formula for the model I fracture toughness of the transversely isotropic material is produced. The characteristics of energy dissipation during the dynamic fracture process of coal, taking the bedding structure into consideration, are obtained by comparing the incident energy, absorbed energy, fracture energy, and residual kinetic energy of Datong coal samples under varied impact speeds. According to the experimental findings, the fracture pattern of Datong coal's notched semi-circular bending (NSCB) represents a tensile failure. The coal sample splits into two pieces and rotates somewhat equally around the spot where it made contact with the incident rod. For Datong coal, the dynamic fracture toughness is 3.52 to 8.64 times greater than the quasi-static fracture toughness [2]. With increasing impact velocity, dynamic fracture toughness rises, and the impact of bedding angle on fracture toughness then falls. Additionally, as the impact speed increases, the residual kinetic energy of coal samples with the same bedding angle rises. The overall statistical data dispersion and energy consumption rate are both steadily declining. Regardless of energy utilization effectiveness or fracture toughness, low-speed loading is the preferred loading condition in rock fragmentation engineering. These findings could have a big impact on how hydraulic fracturing works in coal mass optimization and how to better understand how cracks spread during coal bed methane extraction (CME). Both of these situations call for careful consideration of coal's anisotropic effect [3].