Error estimation based on statically admissible stress fields

In this paper we investigate an approach for a posteriori error estimation based on recovery of an improved stress field satisfying the equilibrium equations locally within a small patch of elements. The stress field is computed through the superconvergent patch recovery (SPR) technique. In contrast to the original SPR-approach which usually provides a lower bound on the true error, the approach presented herein gives in many practical cases a conservative error estimate. The current investigation is carried out for membrane and plate bending problems. Global convergence rates and effectivity indices obtained for benchmark test cases are reported and compared with other variants of SPR.