Limit Analysis of Defect-Free Pipe Elbow Under Internal Pressure With Mean Yield Criterion

With mean yield (MY) criterion, an analytical solution of the collapse load for a defect-free pipe elbow under internal pressure is first obtained. It is a function of ratio of thickness to radius t0/r0, strain hardening exponent n, curvature influence factor m and ultimate tensile strength. The collapse load increases with the increase of m, and it is the same as the burst pressure of straight pipe if m = 1 is assumed. The MY-based solution is compared with those based on Tresca, Mises and twin shear stress (TSS) yield criteria, and the comparison indicates that Tresca and twin shear stress yield criteria predict a lower bound and an upper bound to the collapse load respectively. However, the MY-based solution lies just between the TSS and Tresca solutions, and almost has the same precision with the Mises solution.