Comparison of Three Shear-Deformation Theories in the Non-Linear Analysis of Sandwich Shell Elements
Sandwich shell structures are tipically found in may structural applications. The correct modelling of its structural behaviour is of relevant interest. Shear-deformation effects are always present in sandwich shells due to the difference between the core and skin characteristics. In this work it is formulated and compared a 1st order, a 3rd order and a layerwise shear deformation theories in the geometric and material nonlinear range. In the first two theories both translational and rotational degrees of freedom are laminate dependent, while in the layerwise theory the rotational degrees of freedom are layer dependent. This last theory produces constant shear deformations in each layer, but different from one layer to another. In the 1 st order theory the shear deformations are constant throughout the laminate. In the 3rd order theory, parabolic deformations are directly achieved. The finite element discretisation is made through the degenerated shell element, known as the Ahmad-Irons-Zienkiewicz element . This element has proved to be very good in the analysis of not only arbitrary isotropic shells [2–6], but also composite layered shells [7–14]. Some modifications in the element basic matrices were made in order to follow the new kinematics according to each theory. Some examples are presented in order to discuss the performance of such theories in the analysis of sandwich shells.
KeywordsDisplacement Field Shell Element Laminate Plate Order Theory Shear Deformation Theory
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