Development of a Micromechanic Theory of Constitutive Relations of Polycrystalline Solids
Annual progress rept. 1 Nov 1989-31 Oct 1990
CALIFORNIA UNIV LOS ANGELES DEPT OF CIVIL ENGINEERING
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To analyze structures loaded at elevated temperatures, the stress- strain-time relation of the material is required. This relation given by age hardening and strain hardening theories commonly used often have large discrepancies with experimental results and hence give large errors in the analysis. Lin et al., 1977, suggested calculating polycrystal creep properties from the creep data of single crystals. However, the plastic and creep property of crystals varies larger than those in a polycrystal. There will be significant error to use single crystal data in polycrystal calculations. A f.c.c. crystal has 12 slip system. Plastic and creep property of a crystal depends on the slip in all the 12 slip systems. Instead of waiting for more informative single crystal tests data, we attempt to use the available polycrystal tests. Presently the polycrystal creep property is derived from polycrystal test from its axial and combined tension and shear tests but the non-radial loading data were not used. The non-radial loading has a large effect on the polycrystal creep property. Hence this inclusion of non-radial loading data in the formulation of the polycrystal creep response will improve the calculated strain-time relations and will enhance the accuracy of creep analysis.
- Metallurgy and Metallography