Continuing pressures for higher performance and efficiency in energy conversion and propulsion systems are driving ever more demanding needs for new materials which can survive high stresses at the elevated temperatures. In such severe environments, the characterization of creep properties becomes indispensable. Conventional techniques for the measurement of creep are limited to about 1,700°C. A new method which can be applied at temperatures higher than 2,000°C is strongly demanded. This research presents a non-contact method for the measurements of creep resistance of ultra-high-temperature materials. Using the electrostatic levitation (ESL) facility at NASA MSFC, a spherical sample was rotated quickly enough to cause creep deformation due to the centripetal acceleration. The deformation of the sample was captured with a digital camera, and the images were then analyzed to measure creep deformation and to estimate the stress exponent in the constitutive equation of the power-law creep. To compare experimental results, numerical and analytical analyses on creep deformation of a rotating sphere have been conducted. The experimental, numerical, and analytical results showed a good agreement with one another.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-4594 |
| Date | 01 January 2007 |
| Creators | Lee, Jonghyun |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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