Energy Storage and Absorption of TiNi Shape Memory Alloy under Various Thermomechanical Loading Conditions

Hisaaki Tobushi 3Elzbieta A. Pieczyska 2,4Stefan P. Gadaj 1W. Nowacki 1

1. Polish Academy of Sciences, Institute of Fundamental Technological Research (IPPT PAN), Świętokrzyska 21, Warszawa 00-049, Poland
2. Polish Academy of Sciences, Institute of Fundamental Technological Research (IPPT), Swietokrzyska, Warszawa 00-049, Poland
3. Aichi Institute of Technology (AIT), 1247 Yachigusa, Takusa-cho, Toyota 470-0392, Japan
4. Department of Mechanical Engineering, AICHI Institute of Technology (AIT), 1247, Yachigusa-cho, Toyota 470-0392, Japan

Abstract

The enery storage and absorption characteristics in TiNi shape memory alloys were investigated experimentally based on the superelastic properties under various thermomechanical loading conditions. In the test, the influence of strain rate, cyclic loading and temperature-controlled condition on the characteristics of energy storage and absorption of the material was investigated. In the experiment under the temperature-uncontrolled condition, temperature on the surface of the material was observed and the influence of variation in temperature on the characteristics was clarified. The results obtained can be summarized as follows. (1) In the case of low strai rate, the stress plateaus appear on the stress-strain curves due to the martensitic tranformastion and the reverse transformation during loading and unloading. In the case of high strain rate, the slopes of the stress-strain curves in the phase-transformation regions during loading and unloading are steep. The energy storage per unit volume increases in proportion to temperature, but the dissipted work per unit volume depends slightly on temperature. In the case of low strai rate, the recoverable starin energy and dissipated work do not depend on both strain rate and the temperature-controlled condition. (2) In the case of high strain rate, the recoverable strain energy density decreases and dissipated work density increases in proportion to strain rate under the temperature-controlled condition, while the recoverable strain energy desity increases and dissiptaed work desity decreases under the temperature-uncontrolled condition. In the case of the temperature-uncontrolled condition, temperature varies significantly due to the martensitic transformation and therefore the characteristics of energy storage and absorption differ from these under the temperature-controlled condition.

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium C, by Hisaaki Tobushi
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-06 07:10
Revised:   2009-06-07 00:44