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Analysis of Coupled Thermo-Mechanical Behavior of Shape Memory Alloys using Nonlinear Finite Element Method

Tootian, Mohammad Hassan | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44956 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Naghdabadi, Reza; Arghavani Hadi, Jamal
  7. Abstract:
  8. Unique characteristic behavior of shape memory alloys (SMAs), known as shape memory effect (SME) and superelasticity (SE), make them an appropriate choice for innovative engineering. Design of SMA applications calls for development of constitutive models. To accurately predict SMA behaviors, employing a suitable model with low computational costs is required. In some experimental data, SMAs have coupling in mechanical and thermal behavior. Therefore, mechanical loading changes temperature of the material and variation in temperature affects the mechanical behavior as well. This behavior is called coupled thermo-mechanical effect. In SMA applications, since coupled thermo-mechanical behavior influences mechanical and thermal loadings, its analysis and modeling is important. In current study, the coupled thermo-mechanical behavior of SMAs is studied. Among the well-known SMA models, we choose a model proposed by Brinson which has a simple formulation, shows good agreement with experimental data and is capable to predict primary and secondary effects. Using first and second laws of thermodynamics, constitutive equation of thermo-mechanical coupling based on Brinson model is derived. The proposed equation is simplified to heat transfer equation and solved with other governing equations. Coupled thermo-mechanical equation for three-dimensional Souza model is also developed. Moreover, the proposed coupled equation based on Brinson model is discretized and used in different problems. Also various thermal and mechanical loadings conditions are studied. Using nonlinear finite element method, solution algorithm of the coupled equation based on Souza model is obtained. Result of the proposed coupled equation is compared with other models as well as experimental data. The results indicate that the proposed coupled equation better predict the coupled thermo-mechanical behavior when compared to other models. Brinson model accurately describes coupled thermo-mechanical effect, while, Souza model can be used in 3D finite element software
  9. Keywords:
  10. Shape Memory Alloy ; Constitutive Model ; Brinson Model ; Thermomechanical Coupling Effect ; Three Dimensional Souza Model ; Nonlinear Finite Element Method

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