DEVELOPMENTS IN THE ANALYSIS OF INTERACTING CRACKS

This paper presents an overview of the finite element alternating tech nique for the analysis of interacting cracks. To illustrate the ease a nd accuracy of this method the technique is used to analyse several pr oblems associated with both widespread fatigue and multi-site damage, a problem which is attracting worldwide attention. Whilst this paper p resents an overview of the technique for both two- and three-dimension al problems attention is focused on three-dimensional problems. In par ticular, the interaction effects between two fully embedded elliptical flaws and between two semi-elliptical surface flaws, and the effects of crack proximity and crack aspect ratio on the stress intensity fact ors are presented. For semi-elliptical surface flaws these results ind icate that as the cracks approach each other the position of the point on the crack front with the highest stress intensity factor shifts. T his subsequently suggests that surface cracks will tend to grow prefer entially towards each other. The same trend is evidenced for fully emb edded cracks. However, in this case there is no shift in the position of the maximum stress intensity factor. A discussion of the results in terms of stress intensity magnification factors is also presented.