UC San Diego

Dynamic blast testing of armor components often requires explosives to generate the high pressure, wide area impulses. While explosives provide the most realistic loading conditions, they are difficult to replicate consistently and necessitate remote test facilities for safety. Non-explosive methodologies, such as gas guns and shock tubes, can produce high impulse dynamic events with higher repeatability and increased safety, but are often limited to smaller-sized targets. To impact wide area flexible armor panels with the blast characteristics of a close-in detonation, a non-explosive methodology was investigated using the U.C. San Diego Blast Simulator. The objective was to create a consistent, economical, and scalable methodology for comparing conventional steel and prototype sandwich panel performance with validation of damage modes and extent of damage using actual blast tests and finite element modeling. A tiled projectile array having spatially and temporally varying pressure pulses was developed to replicate the spherical loading profile of a close-in detonation. Using a high speed servo- hydraulic actuator, the projectile was launched at 23.0 - 24.6 m/s, equivalent to 7,520 - 8,460 Pa-s with less than 1.9% standard deviation over 43 tests. This was comparable to 1.37 kg of C4 at 305 mm standoff, which was also used to test five armor panels. Sandwich panel transmitted pressures, measured indirectly via transmission plate acceleration, showed up to 75% reduction in maximum values compared to the steel armor panels, with up to 49% weight savings. Deformation profiles of the non-explosive tested panels were similar in both shape and magnitude compared to the blast tested panels, but with more consistency and symmetry. Blast tested panels showed more extensive core crushing for the sandwich panels but no difference for steel. Finite element modeling predicted similar deformation profiles and transmission plate velocities and accelerations. The models showed higher core crush for the blast tested panels and stress concentrations that matched both sets of test results. The applied impulses for the non-explosive tests were also predicted to be higher than the blast tests. The UCSD Blast Simulator was able to achieve similar levels of damage compared to an actual blast test, with greater repeatability between tests