A unified approach for shear-locking-free triangular and rectangular shellfinite elements

A new concept for the construction of locking-free finite elements for bend ing of shear deformable plates and shells, called DSG (Discrete Shear Gap) method, is presented. The method is based on a pure displacement formulatio n and utilizes only the usual displacement and rotational degrees of freedo m (dof) at the nodes, without additional internal parameters, bubble modes, edge rotations or whatever. One unique rule is derived which can be applie d to both triangular and rectangular elements of arbitrary polynomial order . Due to the nature of the method, the order of numerical integration can b e reduced, thus the elements are actually cheaper than displacement element s with respect to computation time. The resulting triangular elements prove to perform particularly well in comparison with existing elements. The rec tangular elements have a certain relation to the Assumed Natural Strain (AN S) or MITC-elements, in the case of a bilinear interpolation, they are even identical. (C) 2000 Elsevier Science Ltd. All rights reserved.