LOCALIZED LOAD EFFECTS IN HIGH-ORDER BENDING OF SANDWICH PANELS WITH FLEXIBLE CORE

Localized load effects using a high-order theory for the bending behav ior of a sandwich panel with a ''soft'' core (i.e., flexible) in the v ertical direction that is based on variational principles are presente d. The theory embodies a rigorous approach for the small-deformation a nalysis of sandwich plates having high-order effects owing to the nonl inear patterns of the in-plane and vertical deformations of the core t hrough its height. Thus, the high-order and local effects are an inher ent part of the high-order theory and improve on the available classic al and high-order theories. The formulation details the governing equa tions and associated boundary conditions for a general construction of a sandwich panel with unidentical skins and a ''soft'' core made of f oam 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 displac ements in skins, peeling and shear stresses in skin-core interfaces, a nd stress and displacement fields in the core, even in the vicinity of localized loads, The analysis handles any type of load and distinguis hes among loads applied at different skins. A parametric study has bee n conducted on a simply supported sandwich panel with identical skins that are subjected to both a concentrated load applied at the middle o f the panel with a transversely flexible, stiff core and distributed o n a square region with various dimensions for various panel aspect rat ios and to a fully uniform distributed load with various modulus of el asticity ratios of skin panel to core (in vertical direction).