Enhanced tunable fracture properties of the high stiffness hierarchical honeycombs with stochastic Voronoi substructures

Abstract

For multifunctional optimization design of honeycomb structures, the high stiffness hierarchical honeycombs with stochastic Voronoi substructures (HHSVS) are proposed by substituting cell walls of the regular hexagonal honeycombs (ORHH) with Voronoi honeycomb lattices of equal mass. In this study, the tunable linear elastic fracture properties of the HHSVS are investigated by finite element analysis. Results demonstrate that size effect on fracture toughness of the HHSVS is noticeable and a brittleness number is suggested to determine it. At the same time, compared with the ORHH and conventional Voronoi honeycombs of equal mass/density, the in-plane fracture toughness of the HHSVS could be more than 2 times larger and regardless of the cell regularity and hierarchical parameters, fracture toughness of the HHSVS exhibits a weaker quadratic dependence on the relative density and is the highest. As a whole, the HHSVS exhibit the combined properties of tunable Poisson’s ratio, higher stiffness, enhanced tunable fracture toughness, lower imperfection sensitivity and better structural-acoustic performance etc. The research provides a novel strategy for the multifunctional optimization design of the honeycombs structures widely used in the engineering fields. Keywords: Hierarchical honeycombs with stochastic Voronoi substructures (HHSVS), Tunable fracture toughness, Size effect, T-stress