Abstract
Crush behavior of the bare honeycomb structure with hexagonal cell (without the reinforcing plate members bonded on both edges) is studied experimentally and numerically. The dimensions of honeycomb cell used are 3/8in. (9.525mm) and 3/4in. (19.05mm) and the material of foil is an aluminum alloy, A5052. Their foil thicknesses are 0.020mm, 0.033mm and 0.046mm. In experiment, the impact velocity is ranged from 1.98 to 10m/s. As for 3/8in. honeycomb, irregular folding pattern appears just to a little extent in experiment. On the other hand, very irregular buckling pattern is observed in 3/4in. honeycomb. Crush strength becomes slightly larger as the impact velocity increases. The maximum value of acceleration measured by an acceleration sensor attached to the drop-hammer seems to be almost constant when the impact velocity is greater than a certain value, and increases rapidly as the foil thickness increases. Furthermore, numerical simulation is carried out by using the dynamic explicit nonlinear finite element code DYNA3D. In the computation, due to the geometrical symmetry of hexagonal honeycomb core, the 'Y' letter model is proposed. In computation the buckling with folding pattern appears, though, the irregularity in folding pattern is larger in computation than in experiment. Predicted dependence of the crush strength on the impact velocity and the foil thickness is similar to the corresponding experimental result.
