ERROR ESTIMATORS AND ENRICHMENT PROCEDURES FOR THE FINITE-ELEMENT ANALYSIS OF THIN SHEET LARGE-DEFORMATION PROCESSES

An essentially geometric error measure capable of estimating the accuracy with which a faceted element mesh describes the continuous exact geometry of a deforming sheet is presented in this paper. This error is based on an estimated strain tensor between discrete and approximate geometries. Additionally, the paper describes the enrichment process which, at a reasonable computational cost, ensures that the error targets are met whilst generating as few elements as possible. In particular. the enrichment algorithm is based on a judicious combination of two simple operations, namely, side splitting and diagonal swapping. Finally, several applications relating to superplastic forming components are presented.