A Modified Recovery Procedure to Improve the Accuracy of Stress at Central Area of Bilinear Quadrilateral Element

It is found that the accuracy of recovered stress at central area of bilinear quadrilateral element by previous SPR methods 1-3) is inferior. Sometimes, the recovered stress is even worse than the raw result of FEA at that area. This may be due to only recovering the nodal stresses and using them to interpolate the stress elsewhere. To overcome this, the recovery procedure is modified by considering additional nodes located at middle point of element edges and the central point of elements and introducing a weighted average procedure to determine the recovered result at some nodes. Numerical analysis of three examples demonstrates the capability of the new procedure to improve the accuracy of recovery at the central area, and the contribution of the weighted average procedure to the stability of recovery at boundary area.