Energy absorption of flat foldable Miura-ori patterned metamaterials across geometric design space

Abstract

This paper presents a comprehensive study of the compressive energy absorption characteristics of ductile metallic flat foldable Miura-ori patterned metamaterials across the entire geometric design space. Two key questions are addressed. Firstly, to what extent rigid facet folding kinematics captures the material compressive response across the full design space. And secondly, whether the compressive energy absorption is best in regions of the design space where collapse follows folding kinematics well, or where folding kinematics is disrupted. A novel geometric parameter map is introduced to support the navigation of this design space. This is used as a basis for systematically assessing the relationship between geometric parameters, compressive collapse mechanisms and mechanical properties. Analytical models based on rigid facet folding kinematics are developed to predict the quasi-static compressive responses of these metamaterials over large plastic strains. Finite element simulations, spanning a wide range of geometries, are used to validate the analytical models, identify the regions of the design space where folding kinematics is preserved and where these analytical models are applicable, and provide insights into the real collapse mechanisms outside of those regions. The finite element model is also validated against the quasi-static compression test of additively manufactured 316L stainless steel Miura-ori patterned specimen. Finally, design rules are developed to help identify the different regimes of collapse behaviour across the design space.