Hierarchy of key influences on the ballistic strength of opaque and transparent armor

A hierarchic order of influences on the wear resistance of ceramics is adopted here and applied in a modified form on recent ballistic results with sub-micrometer opaque and transparent oxide armor in order to understand interactions between different parameters that govern the ballistic strength. Previously contradictive experimental results such as a fine-grained transparent spinel that outperforms sapphire are explained when the dynamic stiffness (associated with Young's modulus) and the structure of ceramic fragmentation (on penetration) are positioned on the top of the hierarchy, whereas the macro-hardness is addressed as an important parameter, the influence of which, however, depends on the priority levels of the hierarchic ranking.