DISTORTION, DEGENERACY AND REZONING IN FINITE-ELEMENTS - A SURVEY

The results obtained from finite element analysis are significantly af fected by the quality of elements. In certain applications like shape optimization, crash analysis, metal forming, fluid flow analysis, and large displacement analysis, the finite element mesh is systematically updated in an iterative process. In such situations, in spite of an i deal starting mesh, the quality of elements could deteriorate, causing severly distorted elements. In extreme cases, the elements become deg enerate and further progress of analysis is restricted. An understandi ng of the methods of quantifying element distortion helps in identifyi ng 'bad' geometry and in deciding when to remesh. Knowledge about geom etric configurations which cause degeneracy assists in controlling deg eneracy during the analysis. This paper contains a survey of available distortion measures and degeneracy conditions for various elements in two and three dimensions. It is a review of the literature in this fi eld in the last two decades. A brief review of rezoning is also includ ed, since it is one of the more popularly used methods to correct a di storted mesh.