Tungsten Carbide Fragmentation: Experimental Characterization and Numerical Modelling

Tungsten Carbide is a high density ceramic (generally found in ceramic/metal mixtures) with attractive shear and tensile strength properties in certain ballistic applications. We have determined a Hugoniot elastic limit of ~4 GPa, followed by strong hardening behavior, with spall strengths of 2.7-3.6 GPa. In addition, a series of experiments where Tungsten Carbide spheres impacted PMMA indicates that a sharp transition to fine-grained fragmentation occurred at impact velocities between 2.4 and 2.9 km/s. The well-characterized experiments described above were used to assess the effectiveness of CTH in predicting the axial and radial dispersion of the projectile after break-up. CTH has a fracture model that relies on a Pmin criteria to allow computational void to relieve a tensile condition. Comparisons with the experimental data were made using the Pmin model and an additional model based on an energy-based theory of Grady and Kipp. We found that the simple models are not capable of predicting the complex fragmentation behavior seen in the experiments.