Abstract

Crack interaction has been a widely studied topic. However exact formulae for crack interaction factors exist only for the case of coplanar through-wall cracks embedded in an infinite elastic medium subjected to normal loading.

Fitness-For-Service (FFS) and regulatory codes provide rules allowing determining whether multiple flaws shall be combined into a single flaw or evaluated separately. However, these rules set thresholds beyond which flaws are replaced by an envelope sometimes over conservative.

This paper presents closed form formulae for interaction factors of two equal elliptical cracks embedded in an isotropic elastic medium subjected to normal loading. The formulae are based on theoretical developments and Finite Element computations achieved by ESI France in a frame of a large program driven by EDF dealing with interaction of volumetric defects. These defects are modelled as cracks in a conservative way.

Based on the interaction formulae between two cracks, an equivalent crack is defined. These cracks are selected considering the strongest interaction. The process is then repeated with the remaining cracks.

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