Limit Load Solutions for Cracked Elbows Subjected to Internal Pressure and In-Plane Bending

In this article, limit load solutions for cracked elbows containing through-wall and part through-wall axial and circumferential cracks under internal pressure and in-plane bending loading are presented. For elbows with axial cracks, limit pressure solutions are presented, and modifications to existing limit moment solutions are proposed. The foregoing limit pressure and limit moment solutions are used in conjunction with a novel interaction curve to obtain limit load solutions for elbows with axial cracks under combined pressure and moment loading. If the applied moment and pressure are within (outside) the envelope of the interaction curve, no failure (failure) is indicated. Furthermore, limit pressure and limit moment solutions for circumferentially cracked elbows are developed using the same interaction curve. Limit loads computed with the solutions presented in this work are compared with experimental results and the agreement is found to be within acceptable limits after accounting for the uncertainties in the experimental results.