Finite Element Simulation of Sheet Stretched Over a Hemispherical Punch: A Parametric Study

This article presents the results of a parametric study using the finite element method of a full dome hemispherical punch stretching process that is commonly used in the experimental determination of forming limit diagrams (FLDs) of sheet metal. The simulations show the formation of necks, which appear to be a localized neck rather than diffuse necks. With the aid of the parametric study, the roles of friction, strain hardening exponent, strain rate sensitivity, and anisotropy are analyzed for the given punch geometry and their effect on the FLDs explained. The results of finite element simulations done with an imperfection in the element of the sheet where the neck forms are reported and compared with Marciniak-Kuczynski simulations. The simulations are also compared with some experimental results available in the literature.