Effective elastic and transport properties of regular honeycombs for all densities

The effective planar elastic moduli and planar conductivity (or dielectric constant) of regular hexagonal and triangular honeycombs were investigated for the entire range of volume fractions. Only the extreme limits of the volume fraction have been studied in the past. We studied the effective properties both numerically, via finite elements, and analytically, via rigorous three-point bounds, three-point approximations, and cross-property bounds. We show here that the three-point bounds and approximations are generally in excellent agreement with the simulation data and are superior to the two-point Hashin-Shtrikman bounds. Therefore, the three-point estimates provide accurate analytical predictions of the effective properties for all densities. Both the effective bulk modulus and effective conductivity are nearly extremal in the case of hexagonal honeycombs for the entire volume-fraction range, in contrast to the effective shear modulus. In the case of triangular honeycombs, all of the property values are relatively close to being optimal. Thus, the triangular honeycomb has desirable multifunctional performance for all densities in so far as the elastic moduli, conductivity, and dielectric constant are concerned.