Experimental and Numerical Simulation of Coal Rock Impact Energy Index Based on Peridynamics

Table 2

Unloading peak stresses and strains for different types of specimens.

Specimen type and number	Coarse sandstone, CS	Fine sandstone, XS	Mudstone, NY	Top coal seam, 1M	Bottom coal seam, 4M
Unloading peak stress (MPa)	75.41	108.25	63.72	31.87	37.25
Unloading peak strain (10^−2)	1.72	1.17	2.51	1.37	0.74