Experimental and numerical evaluation of CFRP sandwich panels with a novel quasi-hexagonal core under bending and impact loads

This paper investigates the performance of a composite sandwich panel with a novel quasi-hexagonal core through experimental and numerical approaches. To achieve this, laminates made of carbon fiber reinforced polymer (CFRP) are first created using the vacuum-assisted resin transfer molding VARTM method. Then, sandwich panels with the new quasi-hexagonal geometry are fabricated by cutting and assembling the samples. The structures are subjected to three-point bending (TPB) and high-velocity impact (HVI) tests. To validate the conducted tests, the experimental results are compared with data obtained from finite element method (FEM) performed using ABAQUS software. Additionally, to justify the design of the new quasi-hexagonal core, a CFRP sandwich panel with a conventional elliptical-shaped core is produced and tested under a TPB test, allowing for a comparison of its strength with that of the sandwich panel featuring the new quasi-hexagonal core. Finally, the effect of polyurethane foam on specific energy absorption, strength-to-weight ratio, and projectile exit velocity is evaluated in the three mentioned tests. The results demonstrate that the quasi-hexagonal core geometry and polyurethane foam significantly enhance specific energy absorption and flexural strength of the structure, while also effectively reducing the projectile exit velocity in high-velocity impact tests.