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THE DYNAMIC STRESS-STRAIN RELATION OF LEAD AND ITS DEPENDENCE ON GRAIN STRUCTURE
BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
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Several specimens of commercial and high-purity lead of various grain size and crystallographic orientation were loaded dynamically in compression by means of the split Hopkinson bar. Strain rate was held constant at approximately 1200sec for strains up to about 15. The dynamic stress-strain curves were found to lie approximately 50 higher than the corresponding static curves. The compression tests described formed part of a larger project whose purpose was to determine dynamic values of Tabors constant for lead and its dependence on crystal orientation. For this purpose the results of the compression tests were combined with those of dynamic indentation tests previously performed on the same lead specimens. It was found that dynamic values of Tabors constant range from 2.4 to 6.0 depending upon grain size and orientation. These values are approximately equal to the corresponding static values. They may be compared to the value of 2.8 obtained by Tabor and other investigators for numerous fine-grained polycrystalline materials, including lead, and for strains up to about 20.
APPROVED FOR PUBLIC RELEASE