This paper on "An Experimental Comparison of Energy Error Estimators for 8 Noded Isoparametric Quadrilateral Elements" was presented at the 3rd International Conference on Quality Assurance and Standards in Finite Element Analysis - 10-12 September 1991, Stratford-upon-Avon, England.

Summary

Four different methods of estimating the energy error in 8 noded isoparametric quadrilateral elements have been compared. Two different meshes, a three element transition mesh and a four element regular mesh, were subjected to all possible linear and quadratic variations in stress. Exact errors were obtained from the difference between the F.E. stresses and the known analytic solutions. The exact errors were then compared with the error estimates. The best estimates of energy error for this element were obtained from the residual of the equilibrium equations in the element interior. Methods based on evaluating inter element stress jumps performed poorly.