On CFRP honeycomb mechanical metamaterials under out-of-plane crushing

Abstract Honeycomb mechanical metamaterials with semi-re-entrant, square and hexagonal cells were prepared by using continuous twill weave carbon fiber prepreg. Out-of-plane crushing behavior of carbon fiber reinforced polymer (CFRP) honeycomb mechanical materials was investigated experimentally and theoretically. The full-field strain evolution and distribution of buckling modes were obtained. Analytical models were proposed to predict Young's moduli, buckling half-wave numbers, and initial collapse stresses of CFRP honeycomb cores and sandwich panels. The analytical predictions are in good agreement with the experimental results. It is shown that the face sheets have significant effects on the crushing behavior of CFRP honeycombs. The strength, stiffness and energy absorption of CFRP honeycombs are dependent upon the configuration, height and boundary condition. CFRP honeycombs exhibit higher specific strength and specific energy absorption than the counterparts.