An alarmingly large percentage of historical transparent armor replacements were due to damage from rock strike impacts. Consequently, rock strike resistance (RSR) has become an increasingly common feature of transparent armor designs and is required for many military vehicles. In order to assess the factors contributing to materials' RSR, three test methods were evaluated: ballistic aluminum projectile, ballistic ceramic ball, and dropped aluminum indenter, with the latter method being the most reproducible. A standard laminate was then designed and various strike face materials were used to create test samples. By varying the impact energy, an "E50" could be calculated at which 50% of test samples were damaged. Strike face thickness and material affected the E50 and the observed failure modes. Some of the best properties for increasing RSR were found to be contrary to common design practices for transparent armor laminates.
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