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, 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. Here, these results highlight the importance of careful sample recovery, and the risks of relying solely on free-surface velocity measurements.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1480043
- Alternate ID(s):
- OSTI ID: 1465907
- Report Number(s):
- LA-UR-18-22715
- Journal Information:
- Journal of Applied Physics, Vol. 124, Issue 8; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Spall fracture in additive manufactured tantalum
|
journal | December 2018 |
Understanding and predicting damage and failure at grain boundaries in BCC Ta
|
journal | October 2019 |
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