Further studies into interacting 3D cracks

The phenomenon of ageing structures has focused attention on the problem of multiple-site damage (MSD) and wide spread fatigue damage (WFD). In isolat ion each flaw or crack may be safe. However, the cumulative effect of multi ple, interacting cracks may significantly degrade the damage tolerance of t he structure. This paper presents an overview of a new finite element alter nating technique algorithm suitable for calculating mode I stress-intensity factors for an arbitrary number of coplanar interacting three dimensional cracks. This new algorithm has been evaluated for a variety of crack aspect ratios and crack separation ratios for fully embedded elliptical cracks, s emielliptical surface flaws and for quarter elliptical cracks. In each inst ance, test cases have been studied for both finite and infinite geometries. Results of three of these cases are presented in this paper. These results indicate an agreement to within 4% for all cases checked. (C) 1999 Publish ed by Elsevier Science Ltd. All rights reserved.