Mechanical characterization of NiTi SMA wires using a dynamic mechanical analyzer

Roy, Dipankar; Buravalla, Vidyashankar; Mangalgiri, Prakash D.; Allegavi, S.; Ramamurty, U.

doi:10.1016/j.msea.2008.04.052

Cited by 32 publications

(15 citation statements)

References 18 publications

(22 reference statements)

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“…crack initiation, crack growth and final rupture [1]) but also to functional fatigue [2]: when an SMA that exhibits pseudo-elastic behaviour is subjected to cyclic loading, accumulation of permanent strain ensues and the critical stresses for the forward and reverse transformation decrease [2,3]. Functional fatigue has been attributed to either the accumulation of dislocations [3] or the stabilization of martensite variants [4,5] or a combination of these processes [6,7].…”

Section: Introductionmentioning

confidence: 99%

Healing of fatigue damage in NiTi shape memory alloys

Wagner

Nayan

Ramamurty

2008

J. Phys. D: Appl. Phys.

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Progressive accumulation of stress-induced martensite during cyclic loading of NiTi shape memory alloys results in both structural and functional fatigue. We present experimental data demonstrating that periodic annealing of the fatigued samples above the austenite finish temperature ('healing') retransforms the residual martensite back into the parent phase, and therefore enhances the fatigue life (stress-controlled testing, structural fatigue) or partly reverses the changes in the pseudo-elastic hysteresis (strain-controlled testing, functional fatigue).

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Section: Introductionmentioning

confidence: 99%

Healing of fatigue damage in NiTi shape memory alloys

Wagner

Nayan

Ramamurty

2008

J. Phys. D: Appl. Phys.

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“…In a recent work, Roy et al [23] have investigated austenitic fatigue in thin NiTi wires which has significant two-way shape memory due to thermo-mechanical training. They show that at stress levels much higher than the critical stress for the onset of SIM ( SIM ), there is a rapid deterioration in fatigue life compared to those cycled at stresses lower than the critical stress.…”

Section: Introductionmentioning

confidence: 99%

Unnotched fatigue behavior of an austenitic Ni–Ti shape memory alloy

Nayan

Roy

Buravalla

et al. 2008

Materials Science and Engineering: A

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“…These phenomena are difficult to identify by considering only stress-strain curves of superelastic tensile tests. Using Dynamical Mechanical Analysis (DMA) to study shape memory alloys is a classical method to investigate phase transformation temperatures [2,3,4,5,6,7], damping properties [8,9,10,11,12] or effect of fatigue [13]. Classically DMA tests are performed during a temperature sweep under a constant low stress; storage modulus and loss factor are measured as function of temperature.…”

Section: Introductionmentioning

confidence: 99%

Characterizing Transformation Phenomena and Elastic Moduli of Austenite and Oriented Martensite of Superelastic Thin NiTi Wire through Isothermal Dynamic Mechanical Analysis

Alonso

Favier

Chagnon

2019

J. of Materi Eng and Perform

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In this paper, superelastic behavior of Nickel Titanium thin wires is characterized using the method of dynamic mechanical analysis. Nominal dynamic storage modulus ′ is measured as function of nominal strain and stress during isothermal superelastic tensile tests at three testing temperatures above the reverse martensitic transformation finish temperature. The method brings new information on deformation mechanisms compared to the consideration of only tensile stress-strain curves. It is shown that determination of the elastic moduli E, especially at high strain, requires to calculate the true storage modulus ′. Using ′ and not ′, elastic modulus of oriented martensite is determined equal to 73 GPa of the same order than the elastic modulus of austenite equal to 70 GPa. Two models are then proposed to simulate experimental storage moduli evolution during the tests. A first model explains the ′ evolution during stress plateau by the localization phenomenon ; it leads to express ′ as function of the nominal strain. A second model describes the evolution of ′ after the stress plateau as function of true stress and test temperature. This model permits to determine the Clausius-Clapeyron coefficient of the forward transformation.

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Mechanical characterization of NiTi SMA wires using a dynamic mechanical analyzer

Cited by 32 publications

References 18 publications

Healing of fatigue damage in NiTi shape memory alloys

Healing of fatigue damage in NiTi shape memory alloys

Unnotched fatigue behavior of an austenitic Ni–Ti shape memory alloy

Characterizing Transformation Phenomena and Elastic Moduli of Austenite and Oriented Martensite of Superelastic Thin NiTi Wire through Isothermal Dynamic Mechanical Analysis

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