Enhanced rotation-free basic shell triangle for sheet stamping problems

An enhanced version of the rotation-free three node triangular BST shell element for sheet stamping analysis is presented. The original BST element is based on an assumed constant curvature field expressed in terms of the nodal deflections of a patch of four elements and a constant membrane field. An enhanced element is obtained by using a quadratic interpolation of the geometry in terms of the six patch nodes. This allows to compute a linear membrane strain field which improves the in-plane behaviour. An economic version of the element using a single integration point is presented. The efficiency of the new rotation-free shell triangle is demonstrated in the analysis of sheet stamping problems