ON MIXED-INTERPOLATED GENERAL SHELL FINITE ELEMENTS FOR NONLINEAR ANALYSIS

New plate and shell elements for nonlinear finite element analysis are presented. These elements are formulated using three-dimensional continuum mechanics theory with de-generation and mixed-interpolations, and they are applicable to the analysis of thin and moderately thick shells. The mixed-interpolated plate bending elements are based on Reissner/Mindlin plate theory with interpolation of the transverse displacement, section rotations and transverse shear strain components. The elements considered are various 9 and 16-node quadrilateral elements, as well as 7 and 12-node triangular elements. Although the theory for most of these elements had been proposed earlier, the elements have not been studied in great detail. In this thesis the formulation of these elements is summarized and some numerical results are presented which demonstrate the high predictive capabilities of the elements. In the case of a general nonlinear shell analysis, the 9-node mixed-interpolated plate bending element is extended to a general nonlinear shell element. In addition to the separate transverse shear strain interpolation, in-plane strains are also interpolated t