No abstract

In our recent work (Grujicic et al., Int. J. Impact Eng., 2008), various open-literature experimental findings pertaining to the ballistic behavior of soda-lime glass were used to construct a simple, physically based, high strain rate, high-pressure, large-strain mechanical model for this material. The model was structured in such a way that it is suitable for direct incorporation into standard commercial transient non . In general, a good agreement was found between the computational and the experimental results relative to: (a) the front shapes and the propagation velocities of the longitudinal and transverse waves generated in the target during impact and (b) the front shapes and propagation velocities of a coherent-damage zone (a zone surrounding the projectile/target contact surface which contains numerous micron and submicron-size cracks). However, substantial computational analysis/experiment disagreements were found relative to the formation of crack centers, i.e. relative to the presence and distribution of isolated millimeter-size cracks nucleated ahead of the advancing coherent-damage zone front. In the present work, it was shown that these disagreements can be substantially reduced if the glass model (Grujicic et al., Int. J. Impact Eng., 2008) is advanced to include a simple macrocracking algorithm based on the linear elastic fracture mechanics.

No abstract

Molecular-level modelling and simulations of the high-pressure volumetric response and irreversible densification of a prototypical soda-lime glass are first employed. The molecularsimulation results obtained were next used to modify the pressure versus degree-of-compression (the negative of volumetric strain) and yield strength versus pressure relations in order to account for the effects of irreversible densification. These relations are next used to upgrade the equation of state and the strength constitutive laws of an existing material model for glass. This was followed by a set of transient non-linear dynamics calculations of the transverse impact of a glass test plate with a solid right-circular cylindrical steel projectile. The results obtained show that irreversible densification can provide only a minor improvement in the ballistic resistance of glass and only in the case of high-velocity (ca. 1000 m/s) projectiles. Furthermore, it was demonstrated that if the key irreversible compaction parameters can be adjusted by modifications in glass chemistry and microstructure, significant improvements in the glass ballistic resistance can be attained over a relatively wide range of projectile velocities.