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It has been demonstrated that significant weight reductions can be achieved, compared to conventional glass-based armor, when a transparent ceramic is used as the strike face on a glass-polymer laminate. Magnesium aluminate spinel (MgAl 2 O 4 ) and AlON are promising candidate materials for application as a hard front layer in transparent armor. Comprehensive, systematic investigations of the fragmentation of ceramics have shown that the mode of fragmentation is one of the key parameters influencing the ballistic resistance of ceramics. In the study described here, the fragmentation of AlON and three types of spinel was analyzed: two types of fine grained spinel with nominal average grain sizes 0.6 lm and 1.6 lm and a bimodal grain-sized spinel with large grains of 250 lm size in a fine grain (5-20 lm) matrix were examined. The ceramic specimens of 6-mm thickness were glued to an aluminum backing and impacted with armor piercing (AP) projectiles of caliber 7.62 mm at two different velocities-850 m/s and 1100 m/s. The targets were integrated into a target box, which allowed for an almost complete recovery and analysis of the ceramic fragments. Different types of high-speed cameras were applied in order to visualize the different phases of fragment formation and ejection. A laser light-sheet illumination technique was applied in combination with high-speed cameras in order to determine size and speed of ejected ceramic fragments during projectile penetration. The application of the visualization techniques allowed for the analysis of the dynamics of the fragment formation and interaction with the projectile. A significant difference in the fragment size distributions of bimodal grain-sized spinel and AlON was observed.

In the past, the presence of textile fibres in the bullet track of gunshot injuries in body regions covered with clothes was used to differentiate between entrance and exit wounds; as with handguns, a displacement of textile fibres was considered possible only in the direction of the shot. In the present study, the transfer of textile fibres from the entrance and exit regions into the bullet path was systematically investigated with the help of a skin-gelatine composite model. For this purpose, the skin of the bullet entrance and exit region was covered with textile fabric (jeans or jersey material), before conducting four test series of ten test shots each firing a 9-mm Parabellum full-jacketed projectile from a distance of 2 m. The length of the bullet track was 25 and 8 cm, respectively. Subsequently, the bullet tracks were microscopically investigated in sections for the presence of textile fibres. In all the investigated bullet tracks, textile fibres both from the entrance and exit regions could be demonstrated. The distribution pattern depended on the length of the bullet path and the extension of the temporary cavitation. The results are discussed in relation to the relevant literature.

A bullet that has passed in and out of one body segment may continue its way into another part of the body causing a second entrance ("reentry") wound, which is often said to have an atypical and sometimes confusing appearance. To analyze this problem in a systematical approach, 9-mm Parabellum full metal-jacketed projectiles were fired at skin-gelatine composite models simulating the consecutive passage of a bullet through two parts of a body. When there was a distance between the two segments, the primary exit and the reentry skin wounds did not show any distinctive features differing from usual gunshot injuries. In the case of contact between exit and reentry site, the corresponding skin wounds resembled each other as both had central tissue defects surrounded by abrasion areas. The subsequent investigation of the simulant revealed that skin particles from both the exit and the adjacent reentry site had been displaced in the direction of the shot along the whole bullet track of the second segment. The morphological findings are presented and discussed with respect to the pertinent literature, and possible physical ballistic explanations are suggested.

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