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Previous studies have shown that while stainless-steel sandwich panels with pyramidal truss cores have a superior blast resistance to monolithic plates of equal mass per unit area, their ballistic performance is similar to their monolithic counterparts. Here, we explore concepts to enhance the ballistic resistance without changing the volumetric efficiency of the panels by filling the spaces within the core with combinations of polyurethane, alumina prisms, and aramid fiber textiles. The addition of the polyurethane does not enhance the ballistic limit compared with the equivalent monolithic steel plate, even when aramids are added. This poor performance occurs because the polymer is penetrated by a hole enlargement mechanism which does not result in significant projectile deformation or load spreading and engagement of the steel face sheets. By contrast, ceramic inserts deform and erode the projectile and also comminute the ceramic. The ceramic communition (and resultant dilation) results in stretching of both steel face sheets and leads to significant energy dissipation. The ballistic limit of this hybrid is about twice that of the equivalent monolithic steel plate. The addition of a Kevlar fabric to the ceramic hybrid is shown to not significantly change the ballistic limit but does reduce the residual velocities of the debris.

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. The effects water mist has on the overpressures produced by the detonation of 50 lb equivalent of high explosives (HE) TNT, Destex, and PBXN-109 in a chamber is reported. The overpressures for each charge density were measured with and without mist preemptively sprayed into the space. The impulse, initial blast wave, and quasi-static overpressure measured in the blast mitigation experiments were reduced by as much as (40%, 36%, and 35%) for 50 lbs TNT, (43%, 25%, and 33%) for 50 lbs TNT equivalent Destex, and (49%, 39%, and 41%) for 50 lbs TNT equivalent PBXN-109 when water mist was sprayed 60 seconds prior to detonation at a concentration of 70 g/m 3 and droplet Sauter Mean Diameter (SMD) of 54 mm. These results suggest that current water mist technology is a potentially promising concept for the mitigation of overpressure effects produced from the detonation of high explosives. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S)