The low velocity impact response of an aluminium honeycomb sandwich structure

The low velocity impact response of two aluminium honeycomb sandwich structures has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Initially, the rate-sensitivity of the glass fibre reinforced/epoxy skins and aluminium core was investigated through a series of flexure, shear and indentation tests. Here, it was found that the flexural modulus of the composite skins and the shear modulus of the aluminium honeycomb core did not exhibit any strain-rate sensitivity over the conditions investigated here. In addition, it was found that the indentation characteristics of this lightweight sandwich structure can be analysed using a Meyer indentation law, the parameters of which did not exhibit any sensitivity to crosshead displacement rate. The impact response of the aluminium honeycomb sandwich structures was modelled using a simple energy-balance model which accounts for energy absorption in bending, shear and contact effects. Agreement between the energy-balance model and the experimental data was found to be good, particularly at low energies where damage was localised to the core material immediate to the point of impact. The energy balance was also used to identify energy partitioning during the impact event. Here, it was shown that the partition of the incident energy depends strongly on the geometry of the impacting projectile.