Conditions for locking-free elasto-plastic analyses in the Element-Free Galerkin method

The use of finite elements with linear displacement fields in volume-preser ving elasto-plastic problems can lead to volumetric locking. Due to the ina bility of the shape functions to describe certain displacement modes, a res ponse of the structure can be obtained which is much too stiff. The Element -Free Galerkin (EFG) method can provide shape functions that have an intrin sic richer nature and do not exhibit volumetric locking. It is shown that t he finite element (FE) method can be conceived as a specialisation of the E FG method, and that for a specific choice of the EFG parameters the FE shap e functions are retrieved. Then, volumetric locking behaviour is found agai n. However, for other choices of the EFG parameters shape functions are obt ained that are able to describe isochoric elasto-plasticity without volumet ric locking. (C) 1999 Elsevier Science S.A. All rights reserved.