By using the two-dimensional finite element software FRANC2D (Fracture Analysis Code 2D), the calculation of stress intensity factors at the crack tips has been implemented through simulating two collinear cracks and a pair of offset parallel cracks propagation. Interaction and influence between cracks of different geometry patterns with the cracks propagation were discussed. The influence of crack interaction on the direction of propagation was also represented. The results show that the interaction between cracks could produce either an enhancement or a shielding effect on the stress field depending on the geometry of cracks (including the positions of cracks, the lengths of cracks and so on). The stress field of two collinear cracks has always been enhanced and the maximum interaction would occur at the case where the two cracks have the same length. As for a pair of offset parallel cracks, the enhancement and the shielding effecting on the stress field form an inflection point at about the beginning of cracks overlap. The stress field has been affected by the ratio of lateral separation to crack length not the lateral separation 2h for a pair of offset parallel cracks. Once the two cracks overlap, the propagation directions of cracks would turn. The inflection point and turning would fade with the increase of the ratio of lateral separation to crack length. At the same time, some experimental tests were carried out to validate the analysis results.

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