Search for the Edge Crack Emanating from Circular Hole Based on the Data of Strains.

In this study the location of an edge crack emanated from a circular hole and the loading stress are calculated by the data of strains measured around the region of the crack. The location of the crack is determined by the gradient search. In order to avoid the trouble due to local minimum the starting point of searching process is selected based on the fact that the strain field due to crack can be represented by embedded force doublets.