Two hybrid stress membrane finite element families with drilling rotations

Two new assumed stress membrane /nite element families with two translational and one rotational degree of freedomper node are presented. The families, denoted by 8 (M) and 8 (D), are rank su8cient and invariant, and are derived using a uni/ed Hu–Washizu like variational formulation. A recent stress mode classi/cation method is used to illustrate the construction of the stress interpolation matrices. In each family, a number of new formulations are derived. Numerical results are presented