Application of cotton/epoxy laminated composites to fabricate the uni- and bi-‎directional cosine corrugated cores sandwich panels ‎

Polymer matrix laminated ‎composites reinforced by long ‎fibers have many applications due ‎to their appropriate properties. On ‎the other hand, some environmental ‎dangers of artificial fibers in ‎composites have led researchers to ‎consider the possibility of using a ‎variety of natural and renewable ‎fibers in the fabrication of ‎polymeric composites. Sandwich ‎panels are one of the most ‎important structures in different ‎industries. In the present study, the ‎cotton plant fiber and epoxy resin ‎were used to manufacture the core ‎and skins of sandwich panels. ‎Nowadays, uni-directional ‎corrugated cores are widely used in ‎the construction of sandwich ‎structures. In this study, a bi-‎directional corrugated core was ‎proposed to fabricate the sandwich ‎panels made of laminated ‎composites reinforced by natural ‎fibers. Moreover, in order to ‎evaluate the effect of core ‎arrangement, different types of uni-‎directional corrugated cores ‎including longitudinal or transverse ‎with arch upward or downward ‎were considered. Additive ‎manufacturing technology was used ‎to make the core molds. The ‎sandwich panels were subjected to ‎three-point bending loading. ‎Experimental results showed that ‎the sandwich panels with bi-‎directional corrugated core under ‎flexural loading had significant ‎mechanical properties compared to ‎the sandwich panels with uni-‎directional corrugated core. In ‎addition, the results obtained from ‎this study were compared with the ‎corresponding sandwich panels ‎made using glass/epoxy laminated ‎composites. It was found that the ‎flexural properties of the ‎cotton/epoxy sandwich panels were ‎acceptable in comparison with ‎glass/epoxy sandwich panels.‎