http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Superelastic Tension and Bending Characteristics of Shape Memory Alloys
Tokuda, M .,Bundara, B .,Kuselj, B .,Ule, B .,Tuma, J . V . 대한금속재료학회(대한금속학회) 2000 METALS AND MATERIALS International Vol.6 No.4
The objective of this study was to develop a numerical model of the superelastic behavior of shape memory alloys (SMA) on a macro-scale level. Results from a study on this behavior under tension and pure bending tests are presented and discussed. Two SMA samples were used in the experimental work and subjected to various loading paths in tension and pure bending: a single crystalline CuZnAl alloy and polycrystalline NiTi wire. Bending tests were performed under a pure bending loading condition on a new testing apparatus designed for the specific needs of this study. The experimental part of this study focused mainly on the response of the SMA to the loading paths in a quasi-plastic domain where the deformation mechanism is dominantly governed by the stress-induced martensitic transformation. Experimental results obtained from the NiTi polycrystals by tensile tests indicate that the superelastic SMA exhibits sufficient repeatability useful enough for a modeling task, while similar results obtained from the single crystalline CuZnAl indicate that the same modeling approach is not easily feasible. The facts have been qualitatively verified by the experimental data from pure bending tests, and a further area as study is suggested.
Superplastic Deformation under Complex Loading Conditions
Tokuda, M .,Inaba, T .,Ide, A .,Gong, C . B .,Ye, M .,Hu, R . C .,Bundara, B . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4
The initial yield surface of a superplastic material was investigated by using a combined loading of axial force and torque. The thin-walled tubular specimen made of Zn-22 wt.%Al alloy was used in the experimental part of this study. Tests were carried out at room temperature (293 K) and at elevated temperature (523 K). The experimental results show that the material tested did not deform superplastically at 293 K exhibiting a yield surface that can be described by the second invariant of stress deviator (by Mises' criterion). On the other hand, the material was found to deform superplastically at the higher temperature of 523 K with a yield surface more complex compared to that observed at 293 K. This difference may be attributed to the difference in major deformation mechanism at two applied temperatures; that is, the slip within the grains at 293 K and the grain boundary sliding at 523 K.