Citation

Grujicic M, Pandurangan B, Coutris N, Cheeseman BA, Fountzoulas C, Patel P, Templeton DW, Bishnoi KD. Int. J. Impact Eng. 2009; 36(3): 386-401.

Copyright

(Copyright © 2009, Elsevier Publishing)

DOI

10.1016/j.ijimpeng.2008.08.001

PMID

unavailable

Abstract

The critical importance of armor (including transparent armor) has become evident by recent experiences of the U.S. military forces in the Operation Iraqi Freedom. With continuing escalations in the number and variety of threats, the needs for rapidly deployable threat-specific weight/cost-performance-optimized transparent-armor and armor systems have greatly increased. There are numerous efforts by the researchers in the U.S.A. and elsewhere around the world, to help accelerate the development of transparent-armor systems. Traditionally, transparent armor is made of monolithic glass or transparent-elastomer inter-layered glass laminates.

Various open-literature experimental findings pertaining to the ballistic behavior of glass are used to construct a simple, physically based, high strain-rate, high-pressure, large-strain constitutive model for this material. The basic components of the model are constructed in such a way that the model is suitable for direct incorporation into standard commercial transient non-linear dynamics finite-element based software packages like ANSYS/Autodyn [ANSYS/Autodyn version 11.0, User documentation, Century Dynamics Inc. a subsidiary of ANSYS Inc.; 2007.] or ABAQUS/Explicit [ABAQUS version 6.7, User documentation, Dessault systems, 2007.]. To validate the material model, a set of finite element analyses of the Edge-on-Impact (EOI) tests is carried out and the results compared with their experimental counterparts obtained in the recent work of Strassburger et al. [Strassburger E, Patel P, McCauley JW, Kovalchick C, Ramesh KT, Templeton DW. High-speed transmission shadowgraphic and dynamic photoelasticity study of stress wave and impact damage propagation in transparent materials and laminates using the edge-on impact method. In: Proceedings of the twenty-third international symposium on ballistics. Spain: April 2007, and Strassburger E, Patel P, McCauley W, Templeton DW. Visualization of wave propagation and impact damage in a polycrystalline transparent ceramic-AlON. In: Proceedings of the twenty-second international symposium on ballistics. Vancouver, Canada: November 2005.]. Overall, a good agreement is found between the computational and the experimental results pertaining to: (a) the front-shapes and propagation velocities of the longitudinal and transverse waves generated in the target during impact; (b) the front-shapes and propagation velocities of the "coherent-damage" zone (a zone surrounding the projectile/target contact surface which consists of numerous micron- and sub-micron-size cracks); and (c) the formation of "crack centers", i.e. isolated cracks nucleated ahead of the advancing coherent-damage zone front. Relatively minor discrepancies between the computational and the experimental results are attributed to the effects of damage-promoting target-fixturing induced stresses and cutting/grinding-induced flaws located along the narrow faces of the target and the surrounding regions.