A VARIATIONAL METHOD FOR FINITE-ELEMENT STRESS RECOVERY AND ERROR ESTIMATION

A variational method for obtaining smoothed stresses from a finite ele ment derived non-smooth stress field is presented. The method is based on minimizing a functional involving discrete least-squares error plu s a penalty constraint that ensures smoothness of the stress field. An equivalent accuracy criterion is developed for the smoothing analysis which results in a C1-continuous smoothed stress field possessing the same order of accuracy as that found at the superconvergent optimal s tress points of the original finite element analysis. Application of t he smoothing analysis to residual error estimation is also demonstrate d.