Abstract
Crack opening displacement, COD, and stress intensity factor, K_I, of bifurcated cracks are studied experimentally, and are compared with theoretical prediction based on the linear elastic fracture mechanics. The COD of the mother crack and the COD of two branch cracks of a bifurcated crack are measured by Moire interferometry. The COD of the mother crack gives the stress intensity factor, K_IM, that relates to the total energy release rate of the bifurcated crack. On the other hand, the COD of a branch crack gives the stress intensity factor, K_IB, of the branch crack of the bifurcated crack, which K_IB relates to the energy release rate of each branch crack. The measurements say that the value of K_IB approaches to 1/√2 times as large as K_IM in the vicinity of the tips of the branch cracks. This experimental result is in agreement with the theoretical prediction based on the linear elastic fracture mechanics.
