Rotational dependence of the superconvergent patch recovery and its remedyfor 4-node isoparametric quadrilateral elements

The superconvergent patch recovery (SPR) with bilinear interpolation functi ons usually gives good values of recovered stresses in an element patch. Ho wever, when 4-node quadrilateral elements meeting at a node are rigidly rot ated with the essential and natural boundary conditions unchanged, the reco vered stresses obtained by the SPR change and depend upon the local rotatio n of the patch. This can be remedied either by including higher-order terms in the polynomials for the assumed stress distribution in an element patch , or by using linear interpolation functions, which gives inferior accuracy of the recovered stresses near the boundaries of the domain. Additional sa mpling points are suggested to compute the higher-order terms. Copyright (C ) 1999 John Wiley & Sons, Ltd.