Computational Study of a Functionally Graded Ceramic-Metallic Armor

Functionally graded materials FGM are material candidates for niche Army applications such as armor. Development of an FGM with a tailored ceramic-to-metal through-thickness gradient is one approach where an improved mass and space armor material for ballistic protection can conceivably be provided. This work investigates the ballistic efficiency of a postulated FGM ceramic-metallic armor system composed of aluminum nitride AlN and aluminum. The study had two primary objectives 1 development of a method to model an FGM, and 2 examination of the computationally derived ballistic performance of the FGM armor system. The FGM was modeled as a series of discrete bonded layers, with adjusted material parameters such as density and strength, to approximate a gradient structure. The Johnson-Holmquist-Beissel ceramic model was used for the AlN and the Johnson-Cook metal model was used for the aluminum, and the computations were performed using the EPIC code. For a discrete six layer system with appropriately adjusted material parameters, results showed an increase of approximately 15 in the ballistic performance of the simulated FGM when compared to an equivalent target composed of AlN and aluminum. This paper will present the results of the computations of this implementation, and discuss the limitations of the computational approach.