Constitutive models with a more rigorous basis in finite deformation kinematics [ 26 ] and thermodynamics [ 21 ] may enable improvements in descriptions of the bulk behavior of metals [ 2327 ] and ceramics [ 28 ], albeit at increased model complexity and computational expense. Abstract Numerical simulations and analysis of ballistic impact and penetration by tungsten alloy rods into composite targets consisting of layers of aluminum nitride ceramic tile spolymer laminae, and aluminum backing are conducted over a range of impact velocities on the order of 1. As noted already in the context of penetration results for the bare backing metal, the source of discrepancy between model and experiment could not be isolated in these complex multimaterial calculations, but several possibilities can be suggested. Prior to description of the specific problem investigated here and in [ 1 ], an overview of literature on the subject is warranted. Far-field boundary conditions corresponded to free surfaces; that is, the targets were unconfined as in the experiments, though effects of interaction with the mounting apparatus were necessarily excluded in the simulations to maintain a reasonable problem size. In Figure 3 cthe initially unbonded six ceramic tiles have been shattered by the projectile which remains lodged at the back-free surface of the aluminum backing at ms.
Interfaces between layers may strongly influence performance of such systems under ballistic impact.
Mathematical Problems in Engineering
The author declares that there is no conflict of interests regarding the publication of this paper. This mesh density was found to yield sufficiently mesh size-independent results for residual penetration depths and resulting ballistic efficiency ; in fact, an even coarser medium mesh setting was usually deemed sufficient but was not used. When the material deforms elastically,where is the effective strength of the solid that generally depends on strain, strain rate, temperature, pressure, and damage. The thickness of the bare metal target was not listed in the experimental study; a value of was used in the simulations, ensuring independence of residual penetration depth from target thickness. For the aluminum nitride ceramic, Here, is the pressure increment due to bulking, is a material parameter, as are other terms with and subscripts that may take different values for intact and comminuted material [ 17 ].