Sandwich panels have seen limited use on various applications for the U.S. Even after extensive development work, issues such as uniform design parameters; connecting techniques; adherence practices, materials, repair and modification methods; and availability of the honeycomb plastic panels have kept opportunistic growth in the use of laser-welded metallic sandwich panels for naval and other defense and commercial applications. Sandwich panel flexural stiffness, the tensile and compressive strengths of the facesheets, core shear strength and shear modulus, and even the facesheet-to-core bond can be measured. Still, the standard admits that ASTM may be a better choice for determining core shear strength and shear modulus.
The sandwich panel comprise of outer or face sheets separated by an inner core connected to their inside surfaces. They possess a high strength-to-weight ratio since they are light in weight and the core is configured to resist bending of the panel under stress.
Sandwich panels are not only self-supporting but can also bear considerable loads. The dimensions and profile of the facings as well as the thickness and density of the polyurethane foam core are important factors. Sandwich marine panels utilizing aluminum honeycomb cores result in lightweight, high strength structures that are very rigid. Aluminum honeycomb panels have the greatest strength to weight ration of any construction available. Sandwich panel structures based upon highly porous, periodic cellular metal (PCM) structures have attracted significant interest for load supporting structural applications. Cellular alloys with open cell topologies are also attractive heat exchange media where dissipation of high intensity heat in relatively small spaces is required.
Authors bio is coming up shortly. 
