Reduced numerical model to investigate the dynamic behaviour of honeycombs under mixed shear-compression loading

Cellular materials such as aluminium honeycombs combine lightweight with an efficient crash energy absorption capability. They have a major role in a wide range of transport applications to reduce gas emission by the design of lighter structures but remaining safe in accident case. Many investigations on the honeycomb behaviour have been performed, under uni-axial compression loading and more recently under mixed shear-compression loading. The influence of the in-plane orientation has not been however considered. The objective is to develop a reduced numerical model able to investigate, with a reduced cost of calculations, the dynamic behaviour of honeycomb under mixed shear-compression loading and taking into account of the in-plane orientation angle. Reduced model based on the periodicity procedure is developed and its validity range is evaluated. The numerical results show that in terms of pressure-crush curve and collapse mechanisms, the reduced model is consistent with a complete FE model composed of 39 cells with a CPU-time gain efficiency about 97.17%. The reduced model is valid from a loading angle ψ=0° to a loading angle ψlimit contained between ψ=30° and ψ=45°. The reduced model allows investigating in depth the influence of the in-plane orientation and the loading angles on the crush behaviour with minimum time calculations in accord with the validity range.