| Summary: | 碩士 === 國立成功大學 === 工程科學系碩博士班 === 93 === Abstract
Material parameters in the deformation kinetics (DK) and the J2 theory are determined from Darveaux and Banerji shear creep data of 97.5Pb/2.5Sn at 299K, 353K and 407K. The theoretical predictions of two different theories are in very well agreement with the experimental data, but at 299K the theoretical predictions by DK is about 10 times larger than those of J2 theory. However, the predictions of creep strain rate under uniaxial tensile stress of the two theories are not very alike. At various temperatures, the predictions of DK in the stress range higher than the engineering cut-off stress are larger than the predictions of J2, and their tendencies are deviated each other. From Bending/Torsion steady creep analysis of 97.5Pb/2.5Sn thin-walled tubes via DK and J2 theories, the analysis show that (1) under constant temperatures and constant torque with changing bending moment, the coupling effect of bending and twisting of DK on twist rates, are smaller than J2 theory, while the curvature rates of two theories are on the contrary. (2) under constant temperatures and constant bending moment with changing torque, the plot of torsion vs. curvature rate illustrates the coupling effect by bending and twisting of DK on curvature rate , are smaller than J2 theory, while the coupling effect of twist rates are opposite. The methodology of Bending/Torsion steady creep employed in this paper can be used for engineering design.
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