A variationally consistent generalized variable formulation for enhanced strain finite elements

The so-called enhanced strain finite elements are based on the enrichment o f the standard compatible strain field by the introduction of additional, n on-compatible strains. This class of elements can be derived starting from a partial Hu-Washizu variational principle. However, since in the original enhanced strain formulation the stress field is eliminated from the formula tion, a separate least-squares procedure had to be implemented for a variat ional derivation of the stress field. A three-field generalized variable ap proach incorporating strain enhancement is proposed in the present paper wi thin the context of linear elastic structural problems. It is shown how the original two-field enhanced strain method can be naturally recovered by su itably choosing the strain model. For this case a straightforward, but stil l variationally consistent stress recovery is proposed. Copyright (C) 2000 John Wiley & Sons, Ltd.