Development of a one-point quadrature EAS solid-shell element for sheet forming

Abstract

A recently proposed solid-shell finite element based on the Enhanced Assumed Strain (EAS) formulation with a one point quadrature integration scheme is applied to large deformation elastoplastic thin-shell applications including contact. One of the main features of the RESS (Reduced Enhanced Solid Shell) element arises in its minimum number of enhancing parameters (only one), sufficient to circumvent the well-known volumetric and shear locking phenomena, and leading to a computationally efficient performance when compared to other 3D or solid-shell enhanced elements. Also, the element can take an arbitrary number of integration points through thickness direction within a single element layer, which provides a great advantage for spring analysis in sheet forming simulation. An efficient physical stabilization procedure is employed in order to correct the element's rank deficiency. A NUMISHEET2002 benchmark example including contact, plasticity and spring-back phenomenon is carried out with the present formulation, and compared to experimental data.