Material Models Sensitivity of Tungsten-Based Penetrators Impacting on Confined Boron-Carbide
LaSalvia et al. (LaSalvia presentation (2010) Ballistic impact damage in hot- pressed boron carbide 34 ICACC, Daytona Beach, 25–29 Jan 2010) studied experimentally the interaction of confined hot-pressed boron carbide (B4C) targets impacted by laboratory-
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Material Models Sensitivity of Tungsten-Based Penetrators Impacting on Confined Boron-Carbide Costas G. Fountzoulas and J.C. LaSalvia
Abstract LaSalvia et al. (LaSalvia presentation (2010) Ballistic impact damage in hot- pressed boron carbide 34 ICACC, Daytona Beach, 25–29 Jan 2010) studied experimentally the interaction of confined hot-pressed boron carbide (B4C) targets impacted by laboratory-scale tungsten-based long-rod penetrators. To better understand the physics involved, Fountzoulas et al. (Fountzoulas CG, LaSalvia JC (2011) Simulation of the ballistic impact of tungsten-based penetrators on confined hot-pressed boron carbide targets. In: Proceedings of 35th ICACC, Advances in Ceramic Armor VII, p 261) studied by modeling and simulation the ballistic behavior of these targets. To satisfactorily replicate the experimental damage of the targets during impact, the material strength and failure models were iteratively modified. Despite numerous iterations, the damage replication of the target was only partially successful. The fracture of B4C was able to be replicated to some extent but without being able to stop its penetration by the projectile, a disagreement with the experimental observations. The current effort reports on the sensitivity and modification of the existing strength and failure B4C material models of the ANSYS/AUTODYN library to predict the tensile failure to accurately simulate the ballistic response of ceramics. Keywords Tungsten-based penetrators • Johnson-Holmquist (JH) material models • Model parameter sensitivity • Confined targets • Boron carbide • Impact • Penetration
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Introduction
Ceramics are materials that possess characteristics such as low density, high hardness and high compressive strength that make them ideal for use in light armor; however, ceramics are also brittle and have a low tensile strength, which complicates the design of such systems [1]. The pioneering experimental and numerical work of Wilkins and co-workers gave a great deal of insight into the penetration process and failure phenomenology of ceramics utilized in composite armor [2]. Their observations of ceramic failure were further expounded upon by the subsequent work of Shockey et al. [3] who performed a series of experiments with confined ceramic targets impacted by tungsten-nickel-iron rods at velocities from 0.8 to 1.4 km/s and from the recovered targets were able to detail the failure sequence in the ceramic. It was determined that if the projectile velocity is sufficient or if the ceramic is not adequately confined, the projectile loading begins to introduce tensile cracks near the impactor periphery. Ceramics possess low tensile strength and when large tensile stress fields are introduced in the radial direction, they may form ring cracks, concentric around the impact point. Initially shallow, upon continued loading these ring cracks propagate in the direction of maximum principal tensile stress, typically on angles from 25 to 75 normal to the surface. They progress to the back surface of the ce
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