EFFECT OF AN ELASTIC FOUNDATION ON THE BUCKLING AND POSTBUCKLING OF DELAMINATED COMPOSITES UNDER COMPRESSIVE LOADS.

Consider a composite boxed beam filled with a soft elastic medium such as foam or a sandwich beam consisting of two fiber-reinforced sheets separated by a low stiffness core. A bending load on these structures is equivalent to a compressive force on one face and a tensile force on the other; furthermore, a delamination may be present on the compresively loaded composite face. Studies of the delamination problem have been undertaken for the usual case without the elastic foundation. In a recent study the perturbation technique was used to obtain an analytical expression for the initial postbuckling deflections. This solution is extended in the paper for the case of a beam/plate on an elastic foundation. Analytical solutions for the critical load and the initial postbuckling behavior will be derived.