Stress intensity factors of embedded elliptical cracks and an assessment of the ASME XI defect recharacterisation criteria

This paper considers aspects related to the calculation of the stress intensity factors of planar embedded defects in a solid under tension. The determination of stress intensity factor solutions using a modified body force method is described, this technique having certain advantages over existing finite element, boundary element and ordinary body force methods. Furthermore, comprehensive modified body force solutions are presented and discussed for a range of elliptical defect geometries. These solutions have then been used to asses the conservation of the recharacterisation procedure for defects of complex geometry described in Section XI of the ASME Boiler and Pressure Vessel Code. Maximum stress intensity factor values calculated using both the modified body force method and the ASME XI rules in conjunction with standard solutions are compared and contrasted. The results of this analysis show that, by and large, ASME XI is conservative and hence safe. However, geometries for which ASME XI provides non-cservative estimates have been encountered and, in certain circumstances, this may be a cause for concern.