Green Sandwich Composites Fabricated from Flax FRP Facings and Corrugated Cardboard Cores

Abstract

Composite sandwich beams and panels made of fiber-reinforced polymer (FRP) and lightweight, low-density core materials have been shown to be effective in reducing weight and increasing strength and stiffness in a variety of structural applications. The FRP skins resist the tensile and compressive stresses as a result of flexure, similar to the action of the flanges on an I-Beam, while the core resists shear stresses, provides insulation and increases the distance between skins resulting in a higher moment of inertia. In this study, sandwich panels made of green materials are studied. Namely, flax fibers and partial bio-based epoxy were used for the FRP skin and three flute varieties of corrugated cardboard with bulk densities of 127, 138 and 170 kg/m3 were used for the core. A total of 30 small-scale sandwich beam specimens were manufactured across six unique beam varieties with dimensions of 50 mm in width, 25 mm in depth, and 200 and 350 mm in length (150 mm and 300 mm spans) to be tested under four-point bending up to failure. This is an ongoing research and so far 6 of the sandwich beams have been tested and the results are presented in this paper. The load-deflection behavior, load-strain behavior and moment-curvature behavior as well as the strength and stiffness of the sandwich beam specimens were analyzed. Overall, the flax FRP and cardboard sandwiches displayed promising structural behavior and may be considered as a viable, green option for the fabrication of sandwich composite panels. More results will be presented during the conference.