Effects on Fracture Toughness of Adjacent Cracks in the Rectangular Plate : The Mutual Interference between the Center Crack and Symmetrical Edge Cracks

The brittle fracture toughness of the plate with cracks are characterized by the critical stress intensity factor K_<IC> or the critical strain energy release rate of crack extension G_<IC>. Thus, the prediction of strength for a structure requires the knowledge of the stress intensity factor K_1 in terms of the structural configration and loading condition. Several cases of K-values of the plate with a single crack were investigated by many authors. But we have only a few results for the K-values of the plate with several cracks. The aim of this study is to investigate the effect on brittle fracture toughness of adjacent cracks in the rectangular plate. For this purpose, the mutual interference between a center crack and symmetrical edge cracks in the rectangular plate was discussed. The K-values were numerically calculated by using the method proposed by authors, which was the application of the J-integral using the method of superposition of analytical and finite element methods to get good accuracy for extremely coarse finite element. In order to show the reliability of the numerical results, we made an experiment on fracture toughness of the hard polyvinyl chloride rectangular plates with cracks same as the numerical calculated models. The numerical results showed good agreement with the experimental ones.