A Shock Compression Investigation of Failure Waves and Phase Transition in Soda-Lime Glass

Citation

Joshi, Akshay (2021) A Shock Compression Investigation of Failure Waves and Phase Transition in Soda-Lime Glass. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/b8xs-8r91. https://resolver.caltech.edu/CaltechTHESIS:05282021-233441075

Abstract

Soda-lime glass (SLG) and other silica glasses find use in many technological applications involving high pressures and strain rates, such as systems with laser-matter interactions, transparent armor, etc. An experimentally validated constitutive model for these glasses is required for modeling their mechanical behavior at high pressures and strain rates. Also, due to the abundance of silica in the earth's crust, understanding the behavior of these glasses at high pressures can provide significant insights into many geophysical processes. To this end, shock compression experiments are carried out on SLG to study the material's behavior under impact stresses of 5-10 GPa. These experiments are accompanied by numerical simulations and constitutive modeling of SLG to gain further insights into the reported failure-wave phenomenon and phase transitions associated with the material.

The significant findings of this study in relation to the failure-wave phenomenon were the sudden densification/compaction of SLG associated with the failure-wave and the disappearance of the failure-wave phenomenon for impact stresses above 10 GPa. When viewed in the context of the findings from past experiments, these results seem to suggest that localized densification/compaction of SLG causes nucleation of cracks and subsequent comminution in the material under shock compression. These results and observations offer a potential explanation of the mechanism underlying the failure-wave phenomenon.

Further, the shock compression and release experiments performed in this work provided significant insights into the onset of possible phase-transition in SLG under shock compression. A loading-unloading hysteresis is observed in the material’s stress-strain curve for impact stresses higher than 5.8 GPa, with the permanent/residual strain increasing with impact stress. Further analysis of these results strongly indicates that the hysteresis is more likely due to a gradual, irreversible phase transition of SLG than due to regular inelastic behavior. Thus, the results suggest that the SLG undergoes a gradual phase transition to a stiffer phase, although other properties of this phase remain unclear. It can also be noted that this phase transition is postulated to start occurring under shock compression of SLG to stresses above 5 GPa, which is also the threshold stress for the onset of the failure-wave phenomenon. It is, therefore, possible that the two phenomena are interrelated. The experimental results from this study are further used to construct a constitutive model to capture the unloading behavior of SLG.

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