In-plane elasticity of regular hexagonal honeycombs with three different joints: A comparative study

This paper is focused on the in-plane linear elastic properties of regular hexagonal honeycombs with three different joint geometries: hexagonal joint, circular joint and triangular joint. A combination of theoretical and finite element (FE) methods was adopted to investigate their in-plane elastic moduli (Young's modulus, shear modulus and Poisson's ratio), and a good agreement between the two methods was obtained. The influences of the geometric parameters on the elastic moduli, such as ρ*/ρ_S and r/l, were fully discussed. Interestingly, a special relationship can exist among the three joint types, that is, the circular joint can be considered as a minimum circumscribed circle of the hexagonal and triangular joints. Based on this, a comparison among the honeycombs with three different types of joints was conducted. Compared to the conventional regular hexagonal honeycomb, the Young's modulus of the circular joint, hexagonal joint, and triangular joint honeycombs is enhanced by 61%, 80% and 431%, respectively; while the shear modulus is improved by 101%, 133% and 469%, respectively. Consequently, the triangular joint honeycomb was shown to be more successful in micro-structural layout compared with the other two types of honeycombs. This work could be a good guide for the design of novel cellular structures.