Damage development in an armor alumina impacted with ductile metal spheres

Abstract

The present article describes a coupled experimental/computational study of damage development in confined ceramic tiles impacted by spherical metal projectiles. The principal objective is to calibrate the material parameters in the Deshpande-Evans constitutive model for an armor alumina and assess its utility in predicting trends in damage development with impact velocity. The nature of the damage at the impact site is probed through optical and scanning electron microscopy of cross-sections through the impact site as well as surface profile measurements. Once calibrated, the model is used in finite element simulations and shown to predict reasonably accurately the variation in the size of the comminuted zone beneath the impact site with incident projectile velocity. The numerical simulations also provide new insights into the spatial and temporal evolution of subsurface damage and deformation processes as well as the role of metal face sheets in the these processes.

The influence of mechanical and microstructural properties on the rate-dependent fracture strength of ceramics in uniaxial compression

“…Furthermore, because granular plasticity becomes active after material fracture, this mechanism is not relevant to the current study. Studies that investigate the roles of lattice plasticity and granular plasticity during the impact deformation of ceramics were performed by Gamble, Compton and others [1,33,34]. …”

“…An additional benefit is that microstructural features, such as the initial flaw size and flaw density, can be modeled and their effects assessed. The capability of the model has been demonstrated in a number of recent studies comparing finite element simulation results to experimental measurements; these include quasistatic indentation [1], impact on confined ceramic tiles [33], and projectile penetration of ceramic-metal trilayers [34].…”

Large-displacement Lightweight Armor

“…Z and H are key to projectile erosion, but without adequately high values of C and U, sufficient projectile erosion and energy absorption cannot be achieved. Tradeoffs between these parameters and the concomitant change in ballistic performance are not well understood [5]. None of these properties is very useful in predicting ballistic performance unless their behavior can be determined in the high strain rate regimes characteristic of ballistic impact.…”

“…This comes at a cost, as multi-hit performance of ceramics is generally very poor due the extensive cracking that occurs in the vicinity of a projectile impact [5].…”

“…Gas gun tests were conducted in the mechanical testing facilities at the University of California Santa Barbara [5], [12]. The light gas gun utilized in this testing used high pressure nitrogen as a propellant, and had swappable barrels of either 7.62 or 45 mm bore diameters ( Figure 5.1 and Figure 5.2).…”