Ductile fracture of two-dimensional cellular structures

TLDR: In this paper, the authors explored crack growth initiation and subsequent resistance to propagation for regular and irregular hexagonal honeycomb structures made from ductile cell walls, and the dependence of the crack growth behavior upon the cell wall material parameters and geometric imperfections of the structure was investigated.

Abstract: Crack growth initiation and subsequent resistance to propagation are explored numerically for regular and irregular hexagonal honeycomb structures made from ductile cell walls. The elasto-plastic response of the cell walls is described by a bilinear uniaxial stress-strain law, with fracture of the cell walls characterised by the fracture energy per unit area. Estimates for the macroscopic toughness and the associated plastic zone shape are derived analytically on the basis of simple considerations. Crack propagation is simulated numerically by fracturing elements within a finite element model and K-resistance curves are calculated under the assumption of small-scale yielding. The dependence of the crack growth behaviour upon the cell wall material parameters and geometric imperfections of the structure is investigated.