Within the context of leak-before-break (LbB) methodology, this paper presents results from finite element (FE) analyses of a range of complex through-wall cracks in an infinite flat plate subject to combined primary membrane and secondary bending loads. The aim is to provide a simplified approach for the treatment of converging/diverging cracks in LbB assessments. Expressions have been derived from curve fits to FE results, which allow the calculation of the crack opening area (COA) for a complex crack. This expression is based on the crack mouth opening displacement for a straight fronted crack under membrane loading, with modification factors that take account of the crack shape, section thickness and the level of imposed bending stress. The variation of J through the plate thickness has also been studied. Some of the flat plate analyses have been repeated for a straight crack using elastic-plastic material properties. Elastic values of COA are always found to be conservative (i.e. an underestimate) compared to inelastic values. Elastic analyses of a cylinder containing a circumferential defect have also been carried out. These indicate that the crack opening on the inside wall is generally smaller than the crack opening from the corresponding flat plate analysis.

This content is only available via PDF.
You do not currently have access to this content.