WEB 3D Metamaterials: Recent Progress
In this Invited Talk, I review some of our recent conceptual and experimental progress on three-dimensional (3D) rationally designed composites called metamaterials. Metamaterial crystals offer material properties that go beyond (“meta”) those of their constituents and can be seen as the future “meta-inks” of 3D printing (cf. Opt. Photonics News 30, 28 (2019)). In turn, recent progress on 3D printing on the micrometer and nanometer scale has given the field of 3D metamaterials a considerable boost (cf. Nature Rev. Phys. 1, 198 (2019)).
Examples covered in this talk include: (i) Sign inversion of the 3D isotropic thermal expansion coefficient (Sci. Rep. 7, 40643 (2017)). (ii) Negative volumetric effective static compressibility (Extreme Mech. Lett. 22, 165 (2018)). (iii) Static twist effects forbidden in Cauchy elasticity (Science 358, 1072 (2017)). (iv) Tailored chiral characteristic lengths in 3D architectures containing more than one hundred thousand unit cells and more than 300 billion voxels (Adv. Mater., in press (2020); in preparation (2020)). (v) Pronounced acoustical activity at ultrasound frequencies (Nature Commun. 10, 3384 (2019); Materials 12, 3527 (2019); J. Mech. Phys. Solids, submitted (2020)). (vi) 3D quasi-crystalline metamaterials for isotropic chiral behavior (unpublished (2020). (vii) Sign inversion of the effective Hall coefficient (e.g., Phys. Rev. Mater. 3, 015204 (2019)).