Enhanced compressive mechanical properties in stochastic bicontinuous porous structures

Abstract

Inspired by the morphology of dealloyed nanoporous metals, we derive a novel open-celled porous structure with stochastic bicontinuous cell. The polymeric porous specimens are fabricated by additive manufacturing (AM), and the compressive mechanical properties and energy absorption capacity are explored experimentally. Results show that Young’s modulus, yield stress, plateau stress, and energy absorption characteristics are monotonically increasing with the relative density, obeying the Gibson-Ashby power correlation. Due to more defects generated in the specimen with smaller ligament diameter during AM, there is a significant decrease in Young’s modulus and a slight decrease in yield stress with the decrease of ligament diameter, which is opposite to the size effect in nanomaterials. Attributing to the bending and yielding deformation of ligaments, the stochastic bicontinuous porous solids show an enhanced energy absorption capacity. The ligament morphological structure has shown to be an additional factor affecting the mechanical responses of porous solids, and might magnify its sensitivity to structural characteristics. This study provides valuable idea and guidance for designing efficient open-celled porous structures in the promising application of energy absorption.