In-plane dynamics of circular cell hexagonally packaged honeycombs in two principal axes

The in-plane deformation modes, stress-strain curves and energy absorption characteristics of circular cell hexagonally packaged honeycombs with the linear elastic and plastic base material with linear strain hardening are numerically investigated under crushing velocities in two principal axes. Three deformation modes are observed and the empirical formulas for critical velocities of deformation mode transition are derived. With increasing crushing velocities, the fluctuation of stress becomes more intense in the plateau stress phase of stress-strain curves, which appears from low-crushing velocities in x(2) direction, while in x(1) direction at high velocities. Densification strain is linear with t/R ratio for a given crushing velocity, and becomes larger with increasing velocities approximately in a linear relationship under a deformation mode for a given t/R ratio. The law of mean plateau stress is consistent with a one-dimensional shock wave model and static plateau stress is proportional to the square of relative density. Three types of empirical expressions of mean plateau stress are derived. Crushing force efficiency is approximately independent of t/R ratio and sensitive to crushing velocity. Crushing force efficiency becomes smaller and then reduces with increasing velocities, and fluctuates around a level under dynamic mode.