Abstract
Kolsky tension bar techniques were modified for dynamic high-temperature tensile characterization of thin-sheet alloys. An induction coil heater was used to heat the specimen while a cooling system was applied to keep the bars at room temperature during heating. A preload system was developed to generate a small pretension load in the bar system during heating in order to compensate for the effect of thermal expansion generated in the high-temperature tensile specimen. A laser system was applied to directly measure the displacements at both ends of the tensile specimen in order to calculate the strain in the specimen. A pair of high-sensitivity semiconductor strain gages was used to measure the weak transmitted force due to the low flow stress in the thin specimen at elevated temperatures. As an example, the high-temperature Kolsky tension bar was used to characterize a DOP-26 iridium alloy in high-strain-rate tension at 860 s −1 /1030 ∘ C.
Highlights
In this study, the conventional Kolsky tension bar was modified for dynamic high-temperature tensile characterization of thin-sheet alloys
A thin-sheet DOP-26 iridium alloy was characterized in tension at ∼860 s−1/1030 ◦C
The depth of the fixture was made the same as the specimen thickness such that the semicircular cap did not provide additional perpendicular force on the specimen but retained the specimen during dynamic
Summary
The Kolsky tension bar described in [11] was modified for dynamic high-temperature characterization of thin-sheet alloys. Due to the small size of the specimen under investigation, the induction coil was set to heat the relatively large fixtures and let the heat transfer to the specimen (Fig. 1(c)) This experimental design enables direct measurement of displacements at the specimen ends using a laser. Study, the spring was set to generate a pre-tension load of approximately 18 N which is sufficient to straighten the iridium specimen during heating but insufficient to produce further stretch on the iridium specimen. Another high temperature testing issue is thermal softening of the specimen. Combining the measurements of the semiconductor strain gages (Eq (2)) and the laser system (Eq (1)) for specimen stress and strain histories, respectively, yields the stress-strain curve of the specimen under investigation
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