Dynamic crushing of 2D cellular structures: A finite element study

The dynamic crushing behavior of 2D cellular structures is studied by finite element method using ABAQUS/Explicit code. The influences of cell irregularity and impact velocity on the deformation mode and the plateau crush pressure are investigated. Two irregularity-generating methods are used. One is the disorder of nodal locations of a regular hexagonal honeycomb and the other is based on the 2D random Voronoi technique. The results show that the deformation in an irregular honeycomb is more complicated than that in a regular honeycomb due to its cell irregularity. At a low impact velocity, a Quasi-static mode with multiple random shear bands appears, while at a higher impact velocity, a Transitional mode is found, i.e., a mode with localized random shear bands and layerwise collapse bands. Finally, at a much higher impact velocity, a Dynamic mode appears with a narrow localized layerwise collapse band near the crushed end. The velocities for transition between modes are evaluated and expressed by empirical equations. Deformation anisotropy is found in the response of disordered honeycombs but it vanishes with the increase in the irregularity. Statistical results show that the relative energy absorption capacity of cellular materials can be improved by increasing their cell irregularity. This effect is obvious especially at an impact velocity near the mode transition velocity.