Collapse analysis of thin walled pressure vessels using the finite element method

Plastic collapse analysis of three thin walled pressure vessels under internal pressure loading has been carried out using large deflection elasto-plastic finite element analysis with the ANSYS general purpose FEA code implemented in a high end graphic workstation. Multi-linear kinematic hardening plasticity model along with the von Mises yield criterion has been employed for the analysis. The three pressure vessels are of different geometries: the first one is a cylindrical tank with torispherical end domes made of a high strength aluminium alloy; the second is a spherical tank made of titanium alloy and the third one is a toroidal tank fabricated from another aluminium alloy. Stress-strain behaviour of the above metals available from simple tension tests reported in literature and actual experiments is employed for the analysis. Separate properties are used for the parent metal and weldments in the elasto-plastic range. Analytical results are compared with available closed form solutions and burst test results of similar metallic pressure vessels, wherever applicable. Good agreement is found between the computed values and other results.