Effects of pre-pressurization on damage of blast-loaded reinforced plates

The effects of pre-pressurization on blast-loaded reinforced rectangular aluminum plates were studied experimentally. In this study, small (0.508 x 0.609 x 0.0016 meter) clamped plates with rivet attached reinforcing members were used as a basic model of the fuselage skin of a commercial aircraft. Both non-pressurized and pre-pressurized plates (static pressure of 41.4 kPa (6.0 psi)) were considered to simulate the typical in-flight loads experienced by a commercial aircraft due to cabin pressurization. This work extends previous research on blast loading of pre-pressurized plates to incorporate the effects of reinforcing members [1]. An experimental configuration was designed using a vacuum vessel system to apply a pressure differential to the reinforced test plate. Bare spherical explosive charges of C4 were then detonated at fixed distances from the plate. The permanent plate deformations or the amount of tearing in the plates were measured for seventeen explosive tests that considered two different blast load intensities. Additionally, a high-speed camera was used to determine the mechanism and time scale of failure propagation in the reinforced panels. The high speed camera was used found to be an excellent tool to record the failure progression in the reinforced panels under blast loading. In general, commencing with the onset of panel deformation, the blast-loaded panels exhibited rivet failure in less than 0.5 milliseconds, initiation of plate tearing in less than 1.0 millisecond, and completion of plate tearing by about 10.0 milliseconds. A comparison of plate deformations and damage showed two distinct results. For the least intense blast load case, both the non-pressurized and pressurized panels deformed but did not tear. In this case, very little effect of pre-pressurization on final panel deformation was noted. For the more intense blast load case, a significant increase in panel damage was observed as static pre-pressurization increased from 0.0 kPa to 41.4 kPa.