FEM Analysis of the Collapse Strength of a Tube

Using the FEM program, the effects of geometry, residual stress and the elasticplastic behavior of material on the collapse strength of a tube is analyzed and the following results are obtained. The plastic collapse pressure is maximum when the circumferential residual stress on the inner surface is tensile and is equal to 0.7σ_y. The plastic collapse pressure of a perfectly round tube can be approximately estimated by the following equation independent of the plastic-hardening behavior of the material: P = 2σ_0.04 (D/t − 1)/(D/t)². Based on these FEM results, a new formula is presented to evaluate the collapse strength of a tube.