Experimental study on the response of thin aluminium and steel plates subjected to airblast loading

Abstract

This work presents results from an experimental investigation on the influence of stand-off distance on the dynamic response of thin ductile plates subjected to airblast loading. The square plates had an exposed area of 0.3×0.3m2 and were manufactured from two different materials, i.e., medium-strength steel and low-strength aluminium. The airblast loading was generated by detonating spherical charges of plastic explosive at various stand-off distances relative to the centre of the plates. Piezoelectric pressure sensors were used for pressure recordings, and synchronized with two high-speed cameras in a stereoscopic setup to capture the response of the targets. The 0.8 mm thick plates were painted with a speckle pattern to measure the transient deformation fields using a three-dimensional digital image correlation (3D-DIC) technique. The tests covered the entire range of structural response from complete failure at the support to a more counter-intuitive behaviour where the permanent mid-point deflection was in the opposite direction to the incident blast wave due to reversed snap buckling. The synchronization of the pressure and displacement measurements enabled a thorough examination of the entire experiment. The trend in all tests was that the maximum response is driven by the positive impulse from the airblast, as it occurred after the positive duration of the pressure pulse. However, depending on the intensity of the blast load and the structural characteristics, elastic effects and the negative phase could play an important role in the final configuration of the plate. Comparison of the permanent deflection and the measurements from digital image correlation confirmed that this technique is capable of accurately measuring the structural response at high loading rates.