Design and testing of 3D-printed micro-architectured polymer materials exhibiting a negative Poisson’s ratio

Abstract

This work proposes the complete design cycle for several auxetic materials where the cycle consists of three steps (i) the design of the micro-architecture, (ii) the manufacturing of the material and (iii) the testing of the material. We use topology optimization via a level-set method and asymptotic homogenization to obtain periodic micro-architectured materials with a prescribed effective elasticity tensor and Poisson's ratio. The space of admissible micro-architectural shapes that carries orthotropic material symmetry allows to attain shapes with an effective Poisson's ratio below − 1. Moreover, the specimens were manufactured using a commercial stereolithography Ember printer and are mechanically tested. The observed displacement and strain fields during tensile testing obtained by digital image correlation match the predictions from the finite element simulations and demonstrate the efficiency of the design cycle.

Non-auxetic/auxetic transitions inducing modifications of the magnetic anisotropy in CoFe2O4 thin films

“…The archetype of the auxetic structure is the re-entrant honeycomb network, thanks to its peculiarly designed porosity [6,[11][12][13]. Most of the known auxetic materials are artificially designed metamaterials [14] or composites which can be patterned through 3d printing or weaving [3,[15][16][17][18]. Few materials are intrinsically auxetic at the molecular level, because the structure has to feature interior empty spaces to behave in an auxetic way [19][20][21][22].…”

On the design workflow of auxetic metamaterials for structural applications

“…• Topology optimisation [50,70,75]. Shape optimisation involves altering the parameterized geometric characteristics of the unit cell to optimise the desirable material properties of a lattice made of that unit cell.…”

Geometric construction of auxetic metamaterials

“…Martinez et al [MSS*19] generate 2D tile geometries with a graduation of mechanical properties computed as Voronoï diagrams of regular lattices under star‐shaped distance functions. Topology optimization allows to generate new design of auxetic metamaterials with prescribed non‐linear properties computationally [WSJ14, ALS14, VCW*17, ZK19, ACN20]. These various approaches underline the growing interest in auxetic structures in the computer graphics community.…”