Low‐Velocity Impact Response and Damage Characterization of Bio‐Sandwich Composites With Montmorillonite Nanoclay

The bio‐sandwich composites have higher specific stiffness and lower weight than conventional composites under transverse loads. The sandwich composites with same‐thickness glass fiber/epoxy face sheets and a hemp fiber/epoxy core of varying thickness and montmorillonite nanoclay are fabricated using a stirrer and compression molding. The sandwich and monolithic composites are subjected to low‐velocity impact loads using a drop tower test setup. At varying impact energies, force–displacement relationships of sandwich composites G0/H(0) 3 /G0, G0/H(0) 7 /G0, G0/H(0) 9 /G0 with 3 wt% nanoclay and G0/H(0) 5 /G0, G0/H(0) 10 /G0, G0/H(0) 15 /G0 match well and perform better than same‐thickness and same‐weight glass fiber/epoxy laminates G(0) 5 ‐0%, G(0) 8 ‐0%, G(0) 10 ‐0%. The maximum force and specific energy absorption of sandwich panels G0/H(0) 5 /G0‐0%, G0/H(0) 10 /G0‐0%, G0/H(0) 15 /G0‐0% instead of panels G0/H(0) 3 /G0‐3%, G0/H(0) 7 /G0‐3%, G0/H(0) 9 /G0‐3% are higher by a greater extent than same‐weight and same‐thickness monolithic composites G(0) 5 ‐0%, G(0) 8 ‐0%, G(0) 10 ‐0%. At 30 J impact energy, the maximum forces of sandwich panels G0/H(0) 3 /G0, G0/H(0) 7 /G0, and G0/H(0) 9 /G0 with 1, 2, 3, 4, 5 wt% nanoclay are 8%, 17%, 25%, 17%, 7%; 6%, 10%, 16%, 10%, 5%; and 6%, 12%, 19%, 13%, 4% higher than the base panels. This indicates that panels with 3 wt% nanoclay show optimum performance owing to improved interfacial adhesion. At perforation, face sheet/core delamination, large plastic shear deformation, local shear fracture of the core, elastic bending, splitting, and fracture of a larger portion of the bottom face sheet layer occur. Thus, hemp fiber/epoxy core enables better impact performance for bio‐sandwich composites than synthetic composites, providing former material can replace the latter one in structural applications.