Stress Relaxation Effects in TiNi SMA During Superelastic Deformation: Experiment and Constitutive Model
Autor: | Vladimir Dunić, Elzbieta A. Pieczyska, Zbigniew L. Kowalewski |
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Rok vydání: | 2017 |
Předmět: |
010302 applied physics
Materials science Deformation (mechanics) Tension (physics) 02 engineering and technology 021001 nanoscience & nanotechnology SMA 01 natural sciences Stress (mechanics) Mechanics of Materials Martensite 0103 physical sciences Pseudoelasticity Stress relaxation Relaxation (physics) General Materials Science Composite material 0210 nano-technology |
Zdroj: | Shape Memory and Superelasticity. 3:392-402 |
ISSN: | 2199-3858 2199-384X |
Popis: | This paper presents an investigation of thermomechanical effects related to the phenomena of stress relaxation occurring in TiNi SMA subjected to modified program of displacement-controlled tension. The deformation data were taken from testing machine, whereas the temperature changes accompanying the exothermic/endothermic martensite forward/reverse transformation were measured by infrared camera. At the advanced stages of the transformations, the strain was kept constant for a few minutes and the SMA load and temperature were recorded continuously. As a consequence, the stress and temperature changed significantly during the loading stops. A large stress drop, caused by the transformation, was observed during the relaxation stage in both courses of the SMA loading and unloading. Moreover, the non-uniform temperature distribution, reflecting macroscopically inhomogeneous transformation, lapsed while the strain was kept constant, yet restarted at the end of the relaxation stop and developed at the reloading stage. Along with the experimental results, the mechanical and thermal responses induced by the transformation were obtained by 3D coupled thermomechanical numerical analysis, realized in partitioned approach. Latent heat production was correlated with an amount of the martensitic volume fraction. The stress and temperature drops recorded during the experiment were satisfactorily reproduced by the model proposed for the SMA thermomechanical coupling. |
Databáze: | OpenAIRE |
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