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

TL;DR

This paper presents a complete design cycle for creating 3D-printed micro-architectured polymer materials with negative Poisson's ratios, combining topology optimization, manufacturing, and mechanical testing.

Contribution

It introduces a novel design process using topology optimization and homogenization to achieve auxetic materials with tailored negative Poisson's ratios, validated through experimental testing.

Findings

Achieved Poisson's ratio below -1 in micro-architectured materials.

Manufactured specimens match finite element predictions.

Validated the design cycle with mechanical testing and digital image correlation.

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.