Abstract
This paper presents the design of a unique materials-testing system capable of medium strain rates of from 10−4 to 102/s. The design incorporates both closed-loop hydraulic operation with that of open-loop pneumatic operation. A novel design permits accurate specimen alignment and a stiff frame which exceeds 17×106 lb/in. (11.7×104 MPa). The mechanine is able to perform conventional tension/compression tests, fatigue tests and, with slight modification, biaxial-stress-tube tests and triaxial-stress tests. The accurate alignment capability coupled with high frame stiffness and the pneumatic operation enables the testing of brittle materials with rigid grips. Titanium 6-6-2 was tested in both tension and compression at strain rates from 10−4 to about 10/s at four selected temperatures. The material showed a slight strain-rate sensitivity. Yield stress was shown to increase with strain rate while ductility decreased at each test temperature.
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Abbreviations
- f 1,f 2 :
-
frictional forces
- f 3 :
-
the specimen force
- p :
-
charge pressure
- t :
-
time
- V 1 :
-
volume of small reservoir
- \(\alpha _1\) :
-
i=1, 2,….. 6 are constants
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Luntz, R.D., Griffin, R.M., Green, S.J. et al. High-strain-rate tests on titanium 6-6-2 utilizing a unique rate-testing machine. Experimental Mechanics 15, 396–402 (1975). https://doi.org/10.1007/BF02319843
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DOI: https://doi.org/10.1007/BF02319843