Experimental study on the effects of specimen in-plane size on the mechanical behavior of aluminum hexagonal honeycombs

Specimen size affects the mechanical properties of hexagonal honeycombs. Out-of-plane and in-plane uniaxial compression tests are conducted on three kinds of honeycomb specimens with different relative densities to investigate the effects of specimen in-plane size on the mechanical properties of hexagonal honeycombs. Results indicate that an increase in specimen in-plane size causes a decrease in the macroscopic stiffness in the out-of-plane direction (x3-direction) but an increase in that in the in-plane directions (x1-direction and x2-direction). Additionally, the macroscopic stiffness in out-of-plane direction decreases as in-plane size increases up to N×N=13×13, beyond which the macroscopic stiffness becomes stable. The macroscopic stiffness in the in-plane directions increases with the specimen in-plane size up to N×N=9×9. These results serve as bases for determining the minimum specimen in-plane size N×N≥13×13 of hexagonal honeycomb for measuring the effective mechanical properties of a bulk sample of honeycomb.