Effect of peak stress and tensile strain-rate on spall in tantalum
Materials subjected to dynamic environments experience a complex and wide range of stress, strain, and strain-rate conditions. To have confidence in material models, an accurate, predictive capability is required. In this study, we present a series of flyer-plate impact tests on well characterized,...
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Veröffentlicht in: | Journal of applied physics 2018-08, Vol.124 (8) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Materials subjected to dynamic environments experience a complex and wide range of
stress, strain, and strain-rate conditions. To have confidence in material models, an
accurate, predictive capability is required. In this study, we present a series of
flyer-plate impact tests on well characterized, high purity tantalum. The shock-waves
generated at impact release from the free-surfaces, reflect, and interact to produce
incipient spall fracture. By varying the flyer-plate material and impact velocity, both
the peak stress and the strain-rate in the samples were controlled independently.
Velocimetry was used on the rear free-surface of the samples to measure the shock-response
and the spall strength. While this measurement provided the same spall strength for all
cases, at approximately 5.1 GPa, when the samples were sectioned during post-mortem, the
quantity and distribution of internal damage was markedly different. For the high-strain
rate cases, voids remained small and isolated, whereas in the lower strain-rate
experiments, the spall damage was far more localized, with a well-defined continuous spall
plane. With the use of hydrocode simulations, this was discovered to result from how the
different release rates affect the interaction volume inside the sample. These results
highlight the importance of careful sample recovery, and the risks of relying solely on
free-surface velocity measurements. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.5045045 |