Geometrically nonlinear behavior of sandwich plates

The geometrically nonlinear behavior of modern soft-core sandwich plates is studied. For this purpose, a specially tailored geometrically nonlinear finite element that is based on a high-order sandwich plate theory is developed. The theory uses a von Kármán type of geometrical nonlinearity in the face sheets and account for shear and through the thickness deformability of the core. The conversion of the theory to a specially tailored finite element extends its applicability to a wide range of structural layouts, allows the use of standard numerical techniques, and simplifies the coupling with other elements. Yet it avoids the need for meshing through the thickness of the plate. The application of the specially tailored finite element to the geometrically nonlinear analysis of in-plane and out-of-plane loaded sandwich plates explores many interesting physical phenomena. Among them, the evolution of localized instabilities during a globally stable load-deflection behavior, the development of localized diagonal wrinkling patterns, and their impact on the interfacial stresses are listed. The development of unique load resisting mechanisms and, particularly, the evolution of these mechanisms along the geometrically nonlinear response path are also detected. The paper discusses these effects and their role in the geometrically nonlinear behavior of the soft-core sandwich plate.