Localized Load Effects in High-Order Bending of Sandwich Panels with Flexible Core

Abstract

Localized load effects using a high-order theory for the bending behavior of a sandwich panel with a “soft” core (i.e., flexible) in the vertical direction that is based on variational principles are presented. The theory embodies a rigorous approach for the small-deformation analysis of sandwich plates having high-order effects owing to the nonlinear patterns of the in-plane and vertical deformations of the core through its height. Thus, the high-order and local effects are an inherent part of the high-order theory and improve on the available classical and high-order theories. The formulation details the governing equations and associated boundary conditions for a general construction of a sandwich panel with unidentical skins and a “soft” core made of foam or aramid honeycomb. The theory uses a classical thin-plate theory for the skins and a three-dimensional elasticity theory for the core. The behavior is presented in terms of internal resultants and displacements in skins, peeling and shear stresses in skin-core interfaces, and stress and displacement fields in the core, even in the vicinity of localized loads. The analysis handles any type of load and distinguishes among loads applied at different skins. A parametric study has been conducted on a simply supported sandwich panel with identical skins that are subjected to both a concentrated load applied at the middle of the panel with a transversely flexible, stiff core and distributed on a square region with various dimensions for various panel aspect ratios and to a fully uniform distributed load with various modulus of elasticity ratios of skin panel to core (in vertical direction).