STRESSES AND FAILURE PATTERNS IN THE BENDING OF SANDWICH BEAMS WITH TRANSVERSELY FLEXIBLE CORES AND LAMINATED COMPOSITE SKINS

The stresses and failure maps in a sandwich beam that consists of a tr ansversely flexible compressible core between two laminated composite skins, are presented. The stresses and the failure maps are determined using a general, systematic rigorous, and high-order analysis that is based on variational principles, and includes the flexibility effects of the core on the global and local bending behavior of the beam. The analysis uses closed form solutions for any type of skin construction , symmetric or unsymmetric laminated composite layups, any type of cor e, compressible or incompressible, any type of loading, concentrated o r distributed, and any types of boundary and continuity conditions tha t may differ from one skin to the other, even in the same section. Fai lure patterns are determined with the aid of the analytical descriptio n of the longitudinal stresses in the skins and the principal stresses through the thickness of the core. The stresses in the core and the s kins, along with an appropriate failure criteria, for a specified thre e point bending beam, are demonstrated in the form of principal stress es, failure and failure load maps, that indicate possible failure patt erns and locations. Copyright (C) 1996 Elsevier Science Ltd.