Limit load for cylinders with axial internal surface cracks under combined internal pressure and global bending moment

The global and local limit loads for cylinders with axial internal surface cracks under combined internal pressure and global bending moment are investigated using the elastic-perfectly plastic finite element (FE) method. An ellipse function is recommended to describe the relationship between the normalised global limit pressure and normalised global limit bending moment. The predictions using the ellipse function are conservative compared with the global FE results except for the cases with bending moment dominance, where the predictions may be slightly non-conservative. The investigation shows that the local limit load FE results can be well described by the local limit load model recommended by Lei and the predictions are all reasonably conservative except for cases with very long and deep cracks. Further work is required to validate the recommended global and local limit load solutions for J predictions when they are used in the reference stress J scheme.