Compressive and shear characteristics of an octahedral stitched sandwich composite

Octahedral composite sandwich panels were manufactured by integrating upper and lower skins with stitched core to overcome the weak interface between the core and skins of the sandwich structures. Quasi-static compression and shear tests were conducted to get stress–strain curves and to reveal the failure mechanisms of the structure. Dual peak stress was observed during the compression tests and each corresponding to the failure of a constituent layer. The compressive and shear strength was dominated by Euler buckling or fracture of the stitching yarns. To obtain a suitable baseline comparison, the mechanical properties were measured for aramid fiber reinforced honeycomb and aluminum honeycomb core panels. The octahedral stitched composite cores exhibited higher specific shear stiffness/strength and out-of-plane compressive strength than conventional sandwich cores, but showed lower compressive stiffness.