Investigation on the plastic deformation during the stamping of ellipsoidal heads for pressure vessels

Ellipsoidal heads are widely used for constructing thin-walled pressure vessels. Stamping is an efficient way to manufacture massive amount of them, providing fine surface quality and accurately controlled shape. To accurately predict the plastic deformation of the head during the stamping is a vital aspect of controlling head quality. Yet, no satisfactory solution to this has been provided by current industrial standards, including GB/T 150.4-2011, GB/T 25198-2010, GB/T 18442.4-2011, ASME BPVC VIII 2-2017, EN13445-4:2014 and AS4458-1997. Thus, in this paper, equivalent plastic deformation (PEEQ) is proposed to be used for characterizing the plastic deformation. An FEM model was built and was experimentally verified. Then, the detailed perspective to the plastic deformation behavior of the head material during the stamping was provided with assistance of the FEM simulation. An empirical equation to predict the maximum plastic deformation was proposed based on extensive FEM simulations.