Bending theory for multilayer orthotropic sandwich plates.

The governing equations on bending of multilayered orthotropic (both core and facings) sandwich plates are developed through the use of variational methods. The plate is assumed to consist of j facings and (j — 1) cores, having different thicknesses and possessing different orthotropic elastic properties. In-plane stresses in the cores are neglected as is the variation of stresses across the facings. The developed theory is an extension of that given in Ref. 7. Nomenclature a, b = length of rectangular plate in the x- and y-directions, respectively Dxz, Dyz — transverse shear rigidities of plate DXj Dy = bending rigidities of plate in x- and ^-directions, respectively DXy = twisting rigidity of plate Eix, Eiy = Young's moduli of the ith facing in the x- and ^/-directions, respectively Gixz, Giyz = shear moduli of the ith core hi = thickness of the ith core Lr(r = 1-8) = Lagrange multipliers MX, My, MXy = stress couples per unit length of plate NX, Ny, NXy = normal and in-plane shear stress resultants per unit length of plate pz = load function per unit area applied normal to the plate QX) Qy = transverse shear forces per unit length of plate