Keywords: edge dislocations, kinked cracks, edge cracks, opening displacement profile, stress intensity factors, fatigue crack growth, Paris-Erdogan law.

In this study, a simple crack growth emanating from a series of polygon shaped holes in an infinite plate is analysed by using the boundary cracklet method (BCM) which has already proved that it is fast and accurate. Polygon shaped holes are modelled using four-sided regular polygons (square and rhombus) whose sides are created by straight cracks in the subtle implementation of the method.

Interaction effects among crack arrays may strongly reduce the strength and fatigue life of a structure. Interactions are significantly dependent on their placement, geometry, and orientation. There are several studies using various analytical and numerical methods to analyse multiple crack interaction problems [1,2,3]. The BCM is used to predict the stress intensity factors for the cracks emanating from square and rhombus holes during the cyclic loading. The stress intensity factors calculated for several initial crack orientations are found to be in an agreement with the ones found in the literature. The fatigue crack growth is assumed to follow the Paris-Erdogan Law. The results are obtained for the propagation of cracks emanating from square and rhombus holes. As the number of cycles is increased, as expected the crack becomes perpendicular to the applied load direction regardless of its initial orientation. It is found that the higher stress amplitudes cause the higher stress intensity factors. The stress intensity factors are found to be higher for the lower values of initial crack orientations. In the case of lower values of initial crack orientations, it is found that the number of cycles to reach a given crack size is lower compared to the one for the higher values of initial crack orientations. The method presented here predicted the crack propagation for the cracks emanating from square and rhombus holes very well. The method may be used for the other crack propagation problems. These will be the subject of future studies.

1

S.C. TerMaath, S.L. Phoenix, C.-Y. Hui, "A technique for studying interacting cracks of complex geometry in 2D", Engineering Fracture Mechanics, 73, 1086-1114, 2006. doi:10.1016/j.engfracmech.2004.09.009

2

A.K. Yavuz, S.L. Phoenix, S.C. TerMaath, "An accurate and fast analysis for strongly interacting multiple crack configurations including kinked(V) and branched(Y) cracks", International Journal of Solids and Structures, 43, 6727-6750, 2006. doi:10.1016/j.ijsolstr.2006.02.005

3

Y.Z. Chen, N. Hasebe, K.Y. Lee, "Multiple crack problems in elasticity", WIT Press, Southampton, England, U.K., 2003.

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