Tech Briefs

Testing demonstrates effects of blast debris on personnel protective equipment.

As part of Project Agreement on Military Operations in Urban Terrain (MOUT), the US Army Research Laboratory’s (ARL’s) Explosives Effects Branch supported a series of experiments conducted in Meppen, Germany (DEU), to understand loading on personnel protective equipment (PPE) produced during urban weapon attacks. These experiments were conducted by detonating an explosive charge placed on a brick wall to create secondary debris that would impact the US-designed collection medium.

Figure 1. Experimental rooms

The experimental area consisted of 3 separate rooms (Figure 1). The first room was used as the blast room. The second and third rooms contained the collection medium. A double thick brick wall separated rooms 1 and 2 and was used to create the secondary debris.

A wooden collection stand (Figure 2) was designed to hold each collection medium provided for testing. Each stand was precut out of 1.90-cm-thick plywood and assembled on-site. The overall measurements were 172 cm high × 54.61 cm wide. The front window frame was 59.69 cm high × 54.61 cm wide with an opening 50 cm high × 45 cm wide. The stand was configured to be generally representative of a warfighter that is 187.96 cm tall (95th percentile Anthropometric Survey [ANSUR] II study) with a presented chest area of 50.8 cm high × 45.72 cm wide. When placed in the stand, the center of the collection pack was 142 cm high. The stand was fabricated to contain a collection pack consisting of neoprene foam and plastic (50.8 cm wide × 55.88 cm high × 5.75 cm deep). Each collection pack was 5 layers of neoprene foam (11.43 mm) with 0.002 inches (0.05 mm) of plastic interweaved between each layer. The front of the pack utilized 2 layers of plastic.

In addition to the foam collection pack, the wooden stand was designed to hold 2 synthetic gelatin blocks or a combination of gelatin soap and synthetic gelatin for use as the collection medium. Shelves were constructed to support the synthetic gelatin and gelatin soap with dimensions of 25.4 cm wide × 25.4 cm deep. Each shelf was attached to the stand so that the distance from the ground to the center of the collection medium was 142 cm. The synthetic gelatin is designed to have the penetration resistance of 20% that of ballistic gelatin. The benefit of using the synthetic gelatin is that it is not temperature sensitive in contrast to the 20% ballistic gel. The presented area of the gelatin blocks was 20.32 × 20.32 cm.

Figure 2. Collection stand

A double thick brick wall was constructed to separate the blast room from the target room. Two explosive charges were placed on the wall, on the side of the room 1, 142 cm off the ground with a spacing of 49.5 cm from the center point of the wall to create the secondary debris. Three collection stands were used for the blast test. The first stand was located 175 cm from the brick wall in room 2. The foam pack was covered with fabric. Half of the pack was also covered with undergarment material under the first layer of fabric. The soap block and gelatin block of the first stand were covered with a pug material.

The second stand was located 328 cm from the brick wall. The foam was covered half with fabric and half with defender undergarment. The 2 side targets on this stand were synthetic gel blocks covered with a single weave material of various thicknesses. The third stand was located 476.7 cm from the brick wall just behind the doorway of room 3. Half of the foam pack was covered with fabric and the other half was bare. Both the gelatin and soap were bare.

High-speed videography was used to obtain measurements of wall debris velocity and document wall debris spray. The collection medium design proved to be a valuable way to understand the impact from secondary debris, and the stands provided a simple, yet effective way of containing each collection medium.

This work was done by Paul S. Duvall for the Army Research Laboratory. ARL-0194

This Brief includes a Technical Support Package (TSP).

Experimental Setup to Assess Blast and Penetration-Induced Secondary Debris in a Military Operations in Urban Terrain (MOUT) Environment (reference ARL-0194) is currently available for download from the TSP library.

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