High-order theory for the analysis of multi-layer plate assemblies and its application for the analysis of sandwich panels with terminating plies

Abstract Multi-layer sandwich type structures can be identified in many structural assemblies involving composite materials. Such multi-layer composite assemblies are characterized by having interchanging layers of high density and high stiffness separated by compliant interface layers. A characteristic feature of these multi-layer assemblies is that severe and highly localized stress concentrations appear under certain conditions. The quantitative understanding of these phenomena involves a detailed description of the complicated mechanical interaction of the stiff layers through the compliant interface layers. The paper presents a high-order plate theory formulation, which includes the through-thickness flexibility, and which inherently includes a description of the global response as well as the local responses of the individual layers of an arbitrary, multi-layer structural plate assembly. The features of the high-order multi-layer plate theory are demonstrated through analysis of the elastic response of a CFRP/honeycomb-cored sandwich panel with symmetric exterior ply drops. The chosen example involves a 7-layer sandwich plate assembly that changes to a 3-layer assembly at the position of the ply-drops.

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