Close-range blast loading of aluminium foam panels

Full-scale field tests have been carried out in order to investigate the behaviour of aluminium foam panels subjected to blast loading. Charges were detonated at a given standoff distance in front of the foam panels, which were attached to the bob of a ballistic pendulum. Using this test set-up, the maximum swing of the pendulum after each test was used to calculate the energy and impulse transfer from the blast loading. Tests were carried out by varying the foam panel density and charge mass. Experiments were also done with an aluminium cover plate attached to the front of the foam panels. In general, it was observed that the energy and impulse transfer to the pendulum increased by adding a foam panel. In order to investigate this phenomenon, an analytical solution based on shock-wave theory was proposed in order to describe the deformation behaviour of a one-dimensional foam bar subjected to a linearly decaying blast loading. However, using this approach, it was found that the addition of a foam bar should not change the global response of the pendulum. On the other hand, similarities between the present case and recent investigations reported in the literature suggest that the observed increase in maximum swing of the pendulum when adding foam panels may be due to the continuous changing of the shape of the initially plane panel surface into a concave shape. In this way, surface effects could be controlling the energy and impulse transfer.