Flexural Behavior of Sandwich Panels made of FRP Composites: Synthetic and Natural Fibers

Abstract

Sandwich panels made of fiber-reinforced polymer (FRP) skins and light-weight core materials have the potential to be effectively used in several structural applications such as cladding, decking, and roofing panels. The FRP skins resist the tensile and compressive stresses resulting from the flexure induced by transverse loadings and the core resists shear stresses, serves as insulation, and separates the FRP skins at a desired distance to provide required moment of inertial. In this study, two types of fiber materials, namely synthetic (glass) and natural (flax) fibers, as well as two types of core materials, namely polypropylene honeycomb (thickness: 6.4, 12.7, and 25.4 mm; density 80 kg/m3) and cork (thickness: 11 and 22 mm; density 200 kg/m3) core materials were used to make sandwich panels. A total of 105 small-scale sandwich beam specimens (50 mm wide × 200 and 350 mm long) were prepared and tested under four-point bending. The load-deflection behavior, strength, stiffness, and failure mode of the specimens were evaluated. Also, an analytical model was adopted to compute the flexural stiffness, shear rigidity, and core shear modulus of the sandwich panels. The analytical results showed a good agreement with the test results. Overall, the natural fiber and core materials showed a promising structural performance compared to their synthetic counterparts.