Finite-Element Modeling and Experimental Verification of Two-Way Sandwich Panels Made of Natural Fiber Composites

Abstract

Finite-element (FE) modeling of sandwich panels with bidirectional flax fiber–reinforced polymer (FFRP) faces and polyisocyanurate foam cores in two-way bending under concentrated loads was performed. In addition, three large-scale (1,200 × 1,200 mm) sandwich panels with FFRP faces of various thicknesses (one, two, or three layers of flax fabric) and 75-mm-thick foam cores were tested under a concentrated load. The modeling was completed using commercially available software. The material nonlinearity of both the FFRPs and the foam cores was considered as well as the geometric nonlinearity due to localized deformation. Four failure modes were considered: FFRP compression crushing, FFRP tensile rupture, core shear, and compression-face wrinkling. Using the verified model, a parametric study investigated the effect of foam core density, face thickness, core thickness, and size of the loading area. It was found that panels with low-density cores were more susceptible to face-wrinkling failure, while panels with high-density cores were susceptible to both tensile rupture and core-punching shear failure. It was also shown that an increase in the diameter of the loading area decreased the effect of localized deformation for panels with high-density (96 kg/m3) cores.