Numerical analysis of honeycomb structure crushed under oblique impact

In order to improve both the crash safety and fuel efficiency of transport machinery, thin-walled structures of various shapes have been utilized as energy absorbers based on the progressive buckling mechanism. The honeycomb structure is used as a structural member of aircraft due to its high specific strength while it also shows excellent performance as an energy absorbing member. In this study, the dynamic crushing behavior of metal honeycombs due to oblique impact loading was studied with laying emphasis on the effects of the crush angle and the direction of impact loading on their energy absorption characteristics. Finite element models of some metal honeycombs were made by considering the strain rate dependence of material, the plastic deformation and fracture of adhesive layer and the initial imperfection. Some calculated results were compared with the corresponding experimental results, and the validly of those numerical models was verified. Then, the effect of crush angle was discussed through the parametric study with varying the crush angle and the direction of impact loading. The oblique impact loading causes the transition from axial collapse to bending one, so the mean buckling load at the crush angle of 45° was 30-50 % smaller than that for the vertical impact loading, while the structure in the direction parallel to the adhesive layer is slightly stronger. © 2021 The Society of Materials Science, Japan.