Poroelastic metamaterials with negative effective static compressibility
We suggest a three-dimensional metamaterial structure exhibiting an isotropic expansion in response to an increased hydrostatic pressure imposed by a surrounding gas or liquid. We show that this behavior corresponds to a negative absolute (rather than only differential) effective compressibility under truly static and stable conditions. The poroelastic metamaterial is composed of only a single ordinary constituent solid. By detailed numerical parameter studies, we find that a pressure increase of merely one bar can lead to a relative increase in the effective volume exceeding one percent for geometrical structure parameters that should be accessible to fabrication by 3D printing.
3D Metamaterials with Negative Thermal Expansion and Negative Effective Compressibility
Materials with negative thermal expansion are desired for controlling thermal stresses, but unusual in nature. With two-component metamaterials it is possible to tune the thermal expansion from positive over zero to negative values, even if both components have positive thermal expansion. Using gray-tone laser lithography we fabricate three-dimensional two-component polymer microlattices, exhibiting zero or negative thermal expansion [1].
Three-dimensional poroelastic metamaterials with extremely negative or positive effective static volume compressibility
Abstract Recently, three-dimensional poroelastic metamaterials have been introduced that show an unusual isotropic increase of their effective volume when increasing the hydrostatic pressure of the surrounding air. This behavior corresponds to a negative effective static volume compressibility. Here, we present significantly simplified metamaterial architectures, which are composed of just one rather than eight hollow sealed functional elements within each cubic unit cell. On cubic symmetry microstructured polymer samples made by 3D laser printing, we measure a negative effective compressibility of about κ eff = − 4 . 7 % ∕ bar under pressure control. This value is six times larger than pre…