Mechanical properties of the hierarchical honeycombs with stochastic Voronoi sub-structures

¹ Department of Materials Science and Engineering, Tianjin University - Road Weijin 92, 300072, Tianjin, China
² Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento - I-38123 Trento, Italy
³ Center for Materials and Microsystems, Fondazione Bruno Kessler - I-38123 Trento, Italy
⁴ School of Engineering and Materials Science, Queen Mary Univerisity of London - Mile End Road, London, E1 4NS, UK
⁵ Department of Mechanics, School of Mechanical Engineering, Tianjin University - Road Weijin 92, 300072, Tianjin, China

^(a) gongbm@tju.edu.cn (corresponding author)

Received: 15 July 2015
Accepted: 2 September 2015

Abstract

The introduction of hierarchy into structures has been credited with changing mechanical properties. In this study, periodically hierarchical honeycomb with irregular sub-structure cells has been designed based on the Voronoi tessellation algorithm. Numerical investigation has been performed to determine the influence of structural hierarchy and irregularity on the in-plane elastic properties. Irregular hierarchical honeycombs can be up to 3 times stiffer than regular hexagonal honeycombs on an equal density basis. Both the stiffness and Poisson's ratio of the hierarchical honeycomb are insensitive to the degree of regularity, and depend on the cell-wall thickness-to-length ratio of the super-structure. Increasing the relative lengths of the super- and sub-structures results in the increment of Young's modulus, whereas Poisson's ratio almost remains constant varying from 1.0 to 0.7.