This dissertation focuses on developing a predictive method for determining the dynamic
densification behavior of thermite powder mixtures consisting of equivolumetric
mixtures of Ta + Fe₂O₃ and Ta + Bi₂O₃. Of primary importance to these highly reactive
powder mixtures is the ability to characterize the stress at which full compaction occurs,
the crush strength, which can significantly influence the stress required to initiate reaction
during dynamic or impact loading. Examined specifically are the quasi-static and dynamic
compaction responses of these mixtures. Experimentally obtained compaction responses
in the quasi-static regime are analyzed using available compaction models, and an analysis
technique is developed that allows for a correct measurement of the apparent yield strength
of the powder mixtures. The correctly determined apparent yield strength is combined with
an equation of state to yield a prediction of the shock densification response, including the
dynamic crush strength of the thermite powder mixtures. The validated approach is also extended
to the Al + Fe₂O₃ thermite system. It is found that accurate predictions of the crush
strength can be obtained through determination of the apparent yield strength of the powder
mixture when incorporated into the equation of state. It is observed that the predictive
ability in the incomplete compaction region is configurationally dependent for highly heterogeneous
thermite powder systems, which is in turn influenced by particle morphology
and differences in intrinsic properties of constituents (density, strength, etc.).
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/37130 |
| Date | 27 August 2010 |
| Creators | Fredenburg, David Anthony |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Dissertation |
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