Locking-Free Degenerated Isoparametric Shell Element

An 8_noded locking_free degenerated isoparametric shell element is presented. A revised interpolation for shear strain terms was constructed in natural co_ordinate system such that all necessary modes (translation, rotation and constant curvature) are preserved, which can be used to eliminate shear locking. A revised interpolation for membrane strains was produced in the local Cartesian co_ordinate system to overcome membrane locking behavior. The new 8_noded element has the proper rank, with the requisite number of zero eigenvalues each associated with a rigid mode. The element does not exhibit membrane or shear locking for large span_thickness ratio. The element does not form element mechanisms or extra spurious zero energy modes. Therefore, it can be used for both thin and thick shells.