Shape optimisation and buckling analysis of large strain zero Poisson’s ratio fish-cells metamaterial for morphing structures

Abstract

This article investigates the potential of a large strain morphing skin based on a Zero Poisson’s Ratio (ZPR) Fish-Cells metamaterial. A multi-objective genetic algorithm shape optimisation is performed to improve the ZPR characteristics of the Fish-Cells metamaterial. High-fidelity finite element models are developed to assess the performance of the optimised Fish-Cells metamaterial for large non-linear strains. A detailed joint design study is devised to obtain consistent ZPR behaviour over a maximum strain range. Trends of Poisson’s ratio, effective elastic modulus and von-mises stress for the different geometries are discussed in detail. Results provide valuable insight into non-linear behaviour of the Fish-Cells ZPR metamaterial. Furthermore, experimental investigations are conducted to verify the enhanced mechanical behaviour of shape optimised ZPR samples. Linear buckling analysis is performed to assess the performance of the optimised metamaterial under compressive loads. Finally, a preliminary study is conducted to evaluate the performance of the shape optimised ZPR metamaterial as a candidate skin for a morphing aircraft wing.