Developments in the Assessment of Flaw Criticality

The phenomenon of aging structures has focused attention on the problem of multiple site damage (MSD). In isolation each flaw or crack may be safe. However, the cumulative effect of multiple, interacting cracks may significantly degrade the damage tolerance of the structure. Finite element analysis is now routinely used to study isolated cracking. However, with MSD the need for fine meshes around each (interacting) crack tip results in extremely complex and detailed meshes which in turn often require supercomputing facilities. This paper presents a simple alternative for the analysis and assessment of MSD. In this the Schwartz Neumann alternating technique is used and extended to the problem of MSD. To illustrate the power of this technique the problems of two semi-elliptical surface flaws under a bending load and an array of surface flaws under remote tension are considered.