Study on Plastic Collapse Load of Steel Elliptical Heads Under Internal Pressure

A general formula for plastic collapse load of elliptical heads under internal pressure is useful in plastic collapse design and integrity assessment of pressure vessels. Plastic collapse load of steel elliptical heads with different shapes and thickness was computed by finite element analysis using elastic-perfectly plastic constitutive model, and a formula with maximum relative error less than 6% was derived from the numerical results. The formula is a function of the yield strength of materials, the ratio of major axis D_i to minor axis 2h_i and that of outer diameter D_o to inner diameter D_i, and is applicable to steel elliptical heads with D_i/2h_i within 1–2.6 and D_o/D_i within 1.001–1.300.