Study of loading rate effect on dynamic fracture toughness of high strength steel under impact loading

Dynamic fracture toughness (DFT) of a high strength steel, 30CrMnSiA, is determined using a hybrid experimental-numerical method, with a focus on improved understanding of the loading rate effect on DFT under impact loading. The experiments are conducted on the Hopkinson pressure bar (HPB) apparatus with striker velocities ranging from 9.2 to 24.1 m/s to obtain a series of loading rates. Linear-elastic transient finite element analyses are performed to calculate histories of dynamic stress intensity factor (DSIF). The results show that with the increase of striker velocity, the crack tip loading rate increases on the order of 10⁶ MPa m^1/2 s^-1, while the fracture initiation time and the DFT both reduce. Fracture surface examination is also performed to determine the fracture mode of the material.