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.

使用弹塑性有限元 (FE) 方法研究了在组合内压和全局弯矩下具有轴向内表面裂纹的圆柱体的全局和局部极限载荷。建议使用椭圆函数来描述归一化全局极限压力和归一化全局极限弯矩之间的关系。与全局有限元结果相比，使用椭圆函数的预测是保守的，除了弯矩占优势的情况，其中预测可能稍微不保守。调查表明，局部极限载荷有限元结果可以用雷推荐的局部极限载荷模型很好地描述，除了裂缝很长和很深的情况外，预测都相当保守。J预测，当它们用于参考应力J方案时。