Improving lightweight structures is a continuous challenge for yacht hull structural components. Sandwich beams consisting of strong face sheets and a low density core have gained application as weight efficient structures subjected to bending loads. The sandwich structure provides good stiffness by keeping the face sheets at a fixed distance with considerable weight reduction over a statically equivalent monolithic panel. New fabrication technologies now allow for hybrid sandwich structures, known as X-cor to be manufactured. X-cor panels consist of carbon fiber face sheets separated by a closed cell polymer foam core reinforced with carbon fiber or metallic (Titanium or Steel) pins. The pins are inserted into the light weight foam core in the out-of-plane direction and extend from face sheet to face sheet. Pin orientation and concentration can be varied providing a large design space for scientist and designer to explore and to improve material performance. The effect of core thickness, pin reinforcing and polymer foam core on the out-of-plane axial compression response of these panel will be presented. The through thickness three- point simply supported bending behavior of these reinforced panels is used to evaluate the core shear, stretch, face sheet failure characteristics of the structures. Explicit experimental observations are used to develop and calibrate analytical energy balance models to generate failure mode maps describing the panel collapse load as a function of geometry. Multi-scale effective modeling, blurring the distinction between structural and material behavior, will enable optimization of the X-cor sandwich structures in light of Yacht hull design requirements. The mechanical response of X-cor sandwich panels will be compared to current Yacht hull materials using material selection charts, and demonstrator components presented.
ELASTIC BUCKLING STRENGTH OF STEEL SANDWICH PANELS UNDER OUT-OF-PLANE BENDING