Influence of chopped fibers on the interfacial bonding of glass fiber reinforced epoxy skin/polyurethane core in a sandwich composite

In sandwich composites, interfacial bonding between face sheets and core has to be strengthened to prevent debonding. In this work, sandwich composites with polyurethane core and glass fiber reinforced epoxy face sheets were prepared by vacuum infusion process. Chopped fibers of glass, carbon, and kevlar with length 12 mm were introduced between core and face sheets during fabrication in order to improve face‐core bonding. The influence of chopped fibers is investigated by testing flexural, compressive, shear, and fracture toughness properties of prepared specimens according to ASTM standards. Sandwich specimens with chopped glass fibers exhibited, superior interfacial bonding between the face and the core and hence improved the mechanical properties of sandwich composite. The chopped glass fiber embedded sandwich composite has an increased flexural strength of 32.77% and compressive strength of 21.43% when compared with plain sandwich composite. In addition, the shear strength and fracture toughness behavior of specimens with chopped glass fibers are superior when compared to other chopped fibers incorporated in the interfacial region. The interfacial region between skin and core was investigated using scanning electron microscopy (SEM). Chopped glass fibers in the interfacial region showed better adhesion property along with the epoxy. In this paper, chopped fibers of glass, carbon, and kevlar are introduced in the interfacial region to improve face‐core bonding of sandwich composites. The specimens with chopped glass fibers shows an improvement in the fracture toughness and shear strength compared to plain specimens. The approach of interfacial reinforcement may be considered to enhance the performance of sandwich structures used in various applications like transportation, aerospace, and marine industries.