Complete dynamic fracture process of sandstone under impact loading: experiment and analysis

The authors are the first to study the complete dynamic fracture process in the mode-I rock dynamic fracture test by impacting diametrically the holed single cracked flattened Brazilian disc specimens of sandstone with large-di- ameter (ϕ100 mm) split Hopkinson pressure bar ( SHPB). The dynamic crack initiation,propagation and arrest are detected successfully under the low air-pressure loading condition (0. 16-0. 17 MPa) for the projectile of SHPB,and the striking velocity of the projectile is 3． 7-4． 4 m / s. When the crack is arrested,the crack stays stationary for a com- paratively long time before re-initiating. The dynamic initiation time,crack propagation velocity and dynamic arrest time were determined by the time signal measured by the crack propagation gauge. An experimental-numerical-analyti- cal method was adopted to determine the dynamic initiation,propagation,and arrest toughness of sandstone. The effects of loading rate relating to the dynamic initiation toughness and initiation time were analyzed respectively from micro- scale perspective.