ON EVALUATING THE INF-SUP CONDITION FOR PLATE-BENDING ELEMENTS

This paper addresses the evaluation of the inf-sup condition for Reiss ner-Mindlin plate bending elements. This fundamental condition for sta bility and optimality of a mixed finite element scheme is, in general, very difficult to evaluate analytically, considering for example dist orted meshes. Therefore, we develop a numerical test methodology. To d emonstrate the test methodology and to obtain specific results, we app ly it to standard displacement-based elements and elements of the MITC family. Whereas the displacement-based elements fail to satisfy the i nf-sup condition, we fmd that the MITC elements pass our numerical tes t for uniform meshes and a sequence of distorted meshes. (C) 1997 John Wiley & Sons, Ltd.