CREEP CHARACTERISTICS OF TENSION MEMBERS IN HIGH TEMPERATURES BY USING THE PHOTO-SCREEN METHOD.
Rept. for 1 Nov 62-31 Oct 63,
NATIONAL TECHNICAL UNIV ATHENS (GREECE)
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The photo-screen method as it was developed during the previous projects DA-91-591-EUC-1632 and 2021 was applied for the determination of the creep characteristics of various steels and alloys. The photo-screen method for differential moire method developed in the laboratory for Testing Materials was used for the analysis of strains and stresses in externally loaded bodies at elevated temperatures. A technique was developed to reproduce a crossed grating of a density of 500 lines per inch on the surface of the specimens in both principal directions. This grating resisted temperatures up to the flowing point of the material tested. The differential moire method was used for the measurement of relative displacements along the two principal directions of the specimens, from which the longitudinal and transverse components of strains were derived. The influence of temperature on the instability phenomenon due to the nucleation and propagation of Luders bands was studied. Conventional and true longitudinal and transverse stress-strain curves of these materials were traced at various increments of temperature from the ambient up to 450 C 850 F and the resulting lateral contraction ratio true stress or strain curves were plotted. Author