Abstract: Using the digital-laser dynamic caustic system, the impact tests are utilized to investigate the interaction mechanism between a circular hole defect and mode I moving crack. The result shows that, under impact loading, the fracture face is relatively smooth and the growth path is straight towards the hole before the coalescence of moving crack and the round hole. After the moving crack initiates at the top of the round hole, the fracture face is relatively bumpy and the growth path is relatively bent. When the mode I moving crack propagates towards the adjacent round hole, the round hole plays a suppressive effect on crack growth velocity and dynamic stress intensity factor of moving crack. The suppressive effect becomes apparent with the increase of round hole diameter. After the crack-hole coalescence, the moving crack is arrested abruptly and the crack tip becomes blunt. The initiation toughness of the blunt crack increases about 9.58%-13.87% than that of the tip fracture. The crack growth velocity and dynamic stress intensity factor of the blunt crack show obvious jump when the crack initiates again at the hole, indicating that the more energy consumption is needed for blunt crack initiation.

Key words: caustic, moving crack, round hole, crack growth velocity, dynamic stress intensity factor