Effects of pre-pressurization on blast response of clamped aluminum plates

The effects of static pre-pressurization on the blast response of square aluminum plates were studied both experimentally and numerically. Static pre-pressurization values in the range of 0–62.1 kPa (0–9.0 psi) were chosen to represent in-flight loads experienced by the outer skin of a commercial aircraft fuselage due to cabin pressurization. Experimentally, a vacuum vessel system was used to apply a static pressure differential to the test plate. Bare spherical explosive charges were then detonated at a fixed distance from the plate. For load levels that induced only elastic plate deflections, dynamic strains were measured with strain gages located at the center of the test plate. Strain data were recorded for eighteen explosive tests that considered two unique charge sizes. In addition to the experimental work, numerical predictions of the dynamic plate response were determined using finite element analysis. A comparison of the dynamic (elastic) plate strains determined experimentally with those predicted with the finite element method shows good correlation. Only a slight increase (less than 10%) in peak strains was observed as static pre-pressurization increased from 0.0 to 62.1 kPa. For blast load levels that induced plastic deformation in the plates, permanent plate deflections were measured for twenty-four explosive tests at four different blast intensities. A comparison of (plastic) plate deformations determined experimentally with those predicted with the finite element method shows good correlation. For the four explosive load cases studied, no significant change in permanent plate deformations was observed as static pre-pressurization increased from 0.0 to 62.1 kPa.