Constitutive model for a stress- and thermal-induced phase transition in a shape memory polymer

A three-phase constitutive model for TiNiNb shape memory alloys (SMAs) is proposed based on the fact that TiNiNb SMAs are dynamically composed of austenite, martensite and -Nb phases. In the considered ranges of stress and temperature, the behaviors of austenite, martensite and -Nb phases are assumed to be elastoplastic, and the behavior of an SMA is regarded as the dynamic combination of the individual behavior of each phase. Then a macroscopic constitutive description for TiNiNb SMAs is obtained by the conventional theory of plasticity, the theory of mixture, the theory of inclusion, and the description of phase transition by Tanaka. The method for determination of the material parameters is given. This constitutive model can describe the main characteristics of SMAs, such as ferrcelasticity, pseudoelasticity and shape memory effect.

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Effect of loading history on phase transition and martensitic detwinning in shape memory alloys: Limitations of current approaches and development of a 1D constitutive model

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2017.09.138 ◽

2017 ◽

Vol 729 ◽

pp. 390-406 ◽

Cited By ~ 6

Author(s):

Milad Shirani ◽

Masood Taheri Andani ◽

Mahmoud Kadkhodaei ◽

Mohammad Elahinia

Keyword(s):

Phase Transition ◽

Constitutive Model ◽

Shape Memory Alloys ◽

Shape Memory ◽

Loading History

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A constitutive model for shape memory polymers with application to torsion of prismatic bars

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x11431745 ◽

2012 ◽

Vol 23 (2) ◽

pp. 107-116 ◽

Cited By ~ 35

Author(s):

Mostafa Baghani ◽

Reza Naghdabadi ◽

Jamal Arghavani ◽

Saeed Sohrabpour

Keyword(s):

Heat Transfer ◽

Constitutive Model ◽

Shape Memory ◽

Shape Memory Polymer ◽

Shape Memory Polymers ◽

Second Law Of Thermodynamics ◽

Considerable Effect ◽

Heat Transfer Analysis ◽

Internal Variables ◽

Rate Dependent

In this article, satisfying the second law of thermodynamics, we present a 3D constitutive model for shape memory polymers. The model is based on an additive decomposition of the strain into four parts. Also, evolution laws for internal variables during both cooling and heating processes are proposed. Since temperature has considerable effect on the shape memory polymer behavior, for simulation of a shape memory polymer–based structure, it is required to perform a heat-transfer analysis. Commonly, an experimentally observed temperature rate–dependent behavior of shape memory polymers is justified by a rate-dependent glassy temperature, but using the heat-transfer analysis, it is shown that the glassy temperature could be considered as a constant material parameter. To this end, implementing the constitutive model within a nonlinear finite element code, we simulate torsion of a shape memory polymer rectangular bar and a circular tube. Moreover, we compare the predicted results with experimental data recently reported in the literature, which shows a good agreement.

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