On evaluating the inf-sup condition for plate bending

This paper addresses the evaluation of the inf{sup condition for Reissner{Mindlin plate bending elements. This fundamental condition for stability and optimality of a mixed nite element scheme is, in general, very di cult to evaluate analytically, considering for example distorted meshes. Therefore, we develop a numerical test methodology. To demonstrate the test methodology and to obtain speci c results, we apply it to standard displacement-based elements and elements of the MITC family. Whereas the displacement-based elements fail to satisfy the inf{sup condition, we nd that the MITC elements pass our numerical test for uniform meshes and a sequence of distorted meshes.