Dynamic crushing of the circular-celled honeycombs under out-of-plane impact

• An analytical expression of circular honeycombs’ crushing stress is deduced.
• The HP honeycombs show superiority in the energy absorption.
• The energy absorption capacity depends on the constraints around cells.
• The HP honeycomb shows the least sensitivity to the impact velocity.

The dynamic crushing of circular-celled honeycombs under out-of-plane impact is studied within a wide range of impact velocity by using both theoretical and numerical methods, and verified by the experiments. Two kinds of honeycombs with different cell package, i.e., the SP and HP honeycombs, are considered. The results of the honeycombs are discussed and compared with those of the cylindrical tubes under axial compression. An analytical expression is deduced to predict the honeycombs' crushing stress, showing good agreements with the numerical results. It is shown that the energy absorption per unit mass of the HP honeycomb and the SP honeycomb is at least 13.3% and 6.4%, respectively, greater than that of the cylindrical tubes. And the HP honeycomb can absorb at least more 23% energy per unit volume than the SP ones mainly due to the denser package mode of the cells. The different energy absorption ability among the two kinds of honeycombs and the cylindrical tubes can be attributed to the different constraints around the cylindrical cells and tubes, which is verified by the experiments. A non-dimensional “dynamic sensitivity index” is used to quantitatively evaluate the sensitivity of the structure's load capacity to the impact velocity, showing the most sensitivity of the tube and the least sensitivity of the HP honeycomb, which are confirmed by the numerical results.