The air-blast response of sandwich panels with composite face sheets and polymer foam cores: Experiments and predictions

The paper reports on an experimental and numerical investigation into the response of sandwich panels, with PVC foam cores and glass fibre reinforced vinyl ester face sheets, to localised blast loading. It also reports on the response of equivalent mass glass fibre reinforced vinyl ester panels. The loading was generated by detonating discs of plastic explosive at a small stand-off distance of 50 mm. Multiple failure modes were exhibited by the panels, including core compression, fragmentation and complete penetration, debonding between the face sheet and core, delamination between the fibre layers and rupture of the fibres. The sandwich panels exhibited complete penetration failure while no penetration occurred in the equivalent mass composite only panels. Reasonable agreement between the experimental results and numerical simulations is observed. The analysis reveals the reasons why the composite only panels perform better than the sandwich panels with PVC foam core. Due to the lower transverse stiffness of the individual components of the sandwich panel, considerably higher transverse velocity of the face sheet develops at the beginning of the process causing larger deflections and therefore larger in-plane stresses in the face sheet despite the high energy absorbing capacity of the foam core. The influence of the core density on the sandwich panel resistance to blast loading is also briefly discussed.