An improved analytical solution for elastic and elastic-plastic buckling of pipes under hydrostatic pressures

Abstract

An analytical solution for evaluating the critical pressure of pipes under hydrostatic pressure was proposed. The stability equations and the correct boundary conditions for 3D problem in cylindrical coordinates were established by using energy method. The stability equations were solved together with the derived correct boundary conditions and the solution of the critical pressure for elastic buckling of the pipes was expressed in closed form. By adopting the three-layers model for elastic-plastic buckling analysis, the solution was available for the critical pressure prediction of the pipes in elastic-plastic collapse. The effect of the initial ovality was incorporated in formulation. It shows that the increase in the magnitude of the axial compressive stress results in the further reduction in the critical pressure for fully elastic buckling while the pressures for elastic-plastic collapse are always higher than those of the 2D solutions based on the plane strain deformation. The influence of the initial ovality on the pressure capacity of the elastic-plastic buckling of the pipes was discussed and the results from the present approach were compared with the other solutions and experiments.