Experimental Study of the Crossing-Double-Crack Propagation in Q345R Plate

摘要

In this paper, crossing-double-crack fatigue propagation in carbon steel Q345R was tested to investigate the mutual influence between cracks. The two notch-cracks have different lengths and are crossed in different angles. Finite element method was employed to calculate the stress intensity factors at crack tips. It is found that for the crossing-double-crack configuration, new cracks were firstly initiated from the notch-crack tips with the bigger stress intensity factors and then propagated along the paths perpendicular to the applied load. When two new cracks propagate, the other notch-cracks or initiated cracks are shielded without growing. The non-propagated notch-cracks have no obvious effects on the two propagated cracks in terms of the crack growth paths and the crack growth rates. But the two propagated cracks may change the loading state of the non-propagated notch-cracks. The relationships between fatigue crack propagation rates of both single cracks and crossing-double-cracks and the amplitude ranges of the mode I stress intensity factors AK i follow the Paris formula without clear difference.