HIGH-ORDER BENDING OF SANDWICH BEAMS WITH A TRANSVERSELY FLEXIBLE CORE AND UNSYMMETRICAL LAMINATED COMPOSITE SKINS

The bending behavior of a sandwich beam with a ''soft'' core and unsym metrical laminated composite skins has been analytically investigated. The effects of the extension-bending coupling caused by the unsymmetr ical layups on the bending behavior, are presented. The skins may be m ade of different materials, different layups, i.e. symmetrical or unsy mmetrical, different geometries and may have different boundary condit ions (even at the same section). The ''soft'' core is considered compr essible and a change in its height is allowed. The analysis uses varia tional principles and models the core as a two-dimensional elastic med ium, and the skins as one-dimensional composite laminated beams, or a composite panel with cylindrical bending. The analysis is general, rig orous, includes high-order effects and uses closed-form solutions for any type of sandwich construction, for any type of loading and for any combination of boundary conditions. The solutions include the stress and displacement fields along the beam and through the height of the c ore. Local effects in the vicinity of concentrated loads that consist of dimples and high bending moments in the skins and abrupt changes in the peeling stresses, are studied.