Elastic measurements on macroscopic three-dimensional pentamode metamaterials

Pentamode metamaterials approximate tailorable artificial liquids. Recently, microscopic versions of these intricate three-dimensional structures have been fabricated, but direct experimental characterization has not been possible yet. Here, using three-dimensional printing, we fabricate macroscopic polymer-based samples with many different combinations of the small connection diameter d and the lattice constant a. Direct measurements of the static shear modulus and the Young's modulus reveal that both scale approximately according to (d/a)3, in good agreement with continuum-mechanics calculations. For the smallest accessible values of d/a≈1.5%, we find derived ratios of bulk modulus B to shear modulus G of B/G≈1000.