The effects of blast-induced fragments on cellular materials

• The generation and characteristics blast-induced fragments are generated and characterised.
• Different charge diameters and masses are used to create fragments of different sizes and masses propelled at different speeds.
• The use of cellular materials alleviates the damage caused by blast-induced fragment.
• Various cellular materials of thicknesses are placed in front of a witness plate to act as protectors.
• The damage alleviation incurred to the witness plate differs with different energy absorbing materials.

This paper presents the results of an experimental study to characterise blast-induced fragments and to understand how different cellular materials alleviate the damage caused by the blast-induced fragment. In the experimental arrangement, a front plate, 106 mm in diameter, is subjected to a localised blast load to generate a cap fragment (Mode IIc failure) to impact a rear plate of similar dimensions, located parallel and offset from the front plate. Different charge diameters and masses are used to create fragments of different sizes and masses (4.1 g to 12.5 g) propelled at different speeds (244 m/s to 741 m/s). Various cellular materials (aluminium foam, aluminium honeycomb, balsa wood, Corecell M80 foam, Divinycell H200 PVC foam and polyurethane 200 foam) of thicknesses 40 mm and 60 mm are placed in front of the rear plate to act as energy absorbers. The damage caused by the fragment and the protective performance of the cellular materials are quantified by means of the maximum deflection of the rear plate. The results indicate that the cellular materials alleviate the damage incurred to the rear plate, with different materials absorbing different amounts of impact energy. For the range of experiments carried out and foam investigated, the Divinycell foam provided the best protection while Corecell foam offered the least resistance to damage.