The pursuit of enhanced armor materials and the efficient design of armor systems is required to keep pace with the ongoing development of anti-armor weapons. The objective of this dissertation is to improve the ballistic performance of ceramic armor materials and to identify design principles for weight-efficient ceramic armor systems. The approach utilizes numerical simulations combined with validated constitutive models, including the extended Deshpande-Evans model for dynamic ceramic deformation.

The work begins with a numerical study to investigate the effect that design has upon penetration resistance and propensity for failure in ceramic-metal bilayers and trilayers of identical areal density that are subjected to ballistic impact. The results reveal that the ceramic-metal bilayer design offers the greatest resistance to penetration and that the penetration resistance is compromised by taking metal from the rear and placing it at the impacted front of the structure (forming a trilayer). Failure resistance is found to correlate with low relative levels of energy dissipation within the target in contrast to energy dissipation in the projectile. Accordingly, failure resistant designs are found to have large mass ratios of ceramic-to-metal.

Relationships between the material properties and the rate-dependent fracture strength of ceramics are determined, which enable the development ceramics with improved ballistic performance through manufacturing. Dynamic strengthening observed at high rates is attributed to two mechanisms that inhibit microcrack growth and thus delay the fracture process: (i) radial inertia-induced confinement and (ii) the finite velocity of microcracks. Two key parameters, the quasistatic strength and the critical strain rate, are determined as functions of material properties. Using these parameters a universal scaling relationship is developed that describes the rate-dependent compressive strength of ceramics in a state of uniaxial stress.

The limit to the interface defeat capability of ceramics is investigated under a constant force loading condition. While not observing dwell, we find that below a critical load interface defeat is observed and above a critical load penetration occurs at a constant rate. Suppression of microcracking is found to significantly increase the interface defeat threshold of ceramics.