Experiments and numerical simulations studied the mechanics of two interacting colinear and offset cracks. Quasi-static experiments were carried out on acrylic sheets to determine the crack growth direction in the specimens with double parallel cracks or a single crack. The Finite Element Method (FEM) was adopted to calculate stress intensity factors at the crack tips. The interaction and influence of crack growth and direction of propagation with various geometries of cracks and their positions were discussed. This interaction is observed through a change in the propagation directions of crack tips. As the cracks grow, the SIF at the crack tip continuously increases. When the cracks are very close, SIF sharply increases for the colinear case. Crack growth behavior is observed, and the stress intensity factor is calculated at each step of crack growth for both cracks. The interaction effect on the crack path during propagation in simulation is predicted by the Maximum Tangential Stress (MTS) criterion. Some experiments are conducted to validate the analysis results. Comparisons are also made with experiments conducted under this study.
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