A sandwich structure is comprised of layered composite materials formed by bonding two or more thin facings or facesheets to a relatively thick core material. This article describes the sandwich panel failure modes. It tabulates the nomenclature and definitions for loads, geometry, and material properties. The article illustrates critical strength-check locations for a flat sandwich panel. It discusses the analysis methods formulated for flat rectangular honeycomb panels; curved sandwich panel; and for each of the various sandwich panel failure modes. The article concludes with a discussion on flat panel stability analysis methods.

This paper presents an analysis methodology for composite sandwich panel 90° closeout with multi-layered non-uniform facesheets and core. A detailed 2D finite element model was constructed to model honeycomb core through the thickness as well as simulate top and bottom facesheets and the transition region. 2D equivalent material properties of the facesheets are calculated based on classical lamination theory. Elemental stresses of core are used to calculate failure index and margin of safety for various loading conditions based on tension/compression and shear interaction theory. Facesheet strength is checked by interlaminar shear and tension interaction equation with the utilization of failure index. Theoretical failure modes and critical locations obtained from this approach are compared with structural testing of specimens. The predicted failure loads, deflection, facesheet load ratio, and strains are in good agreement with test data. The methodology is verified to be a simple, efficient, and reliable method for the analysis of composite sandwich closeout structures.

No abstract

No abstract

No abstract