Manufacturing and testing of a sandwich panel honeycomb core reinforced with natural-fiber fabrics

A novel honeycomb core made of a natural-fiber reinforced composite consisting of a vinylester matrix reinforced with jute fabric is introduced. Six-mm- and 10-mm-cell honeycombs are manufactured using two compression-molding techniques. Best results are obtained for the mold with lateral compression. Experimental tests are conducted to characterize the elastic response of the composite and the core response under flatwise compression. The effective elastic properties of the core are computed via a homogenization analysis and finite element modeling. The results of the homogenization analysis are in very good agreement with estimations done using analytical formulas from the bibliography. The flatwise compression tests show that the core failure mechanisms are yarn pull-out and fiber breaking. The large wall thickness relative to the cell size of the jute–vinylester cores, which inhibits buckling, and the heterogeneities in the composite, which are preferential damage initiation sites, explain the observed behavior. When compared in terms of the specific strengths, the jute/vinylester cores introduced in this work show similar performances to those of their commercially available counterparts. The results from this study suggest that jute-reinforced cores have the potential to be an alternative to standard cores in applications that sustain compressive static loads.