Transient heat transfer effects on the pseudoelastic behavior of shape-memory wires

Leo, Perry H.; Shield, T. W.; Bruno, Oscar P.

doi:10.1016/0956-7151(93)90328-p

Cited by 202 publications

(137 citation statements)

References 6 publications

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“…At the higher measurement stress levels, the samples continued to accumulate strain before reaching (within a few minutes) the strain levels marked with black dots. This effect is attributed to the relatively high loading rate which did not allow sufficient time for transformation enthalpy dissipation [11][12][13]. Since the transformation is thermoelastic, a strain is produced in the sample upon equilibrating to ambient temperature.…”

Section: Methodsmentioning

confidence: 99%

Stress-induced martensitic transformations in NiTi and NiTi–TiC composites investigated by neutron diffraction

Vaidyanathan

Bourke

Dunand

1999

Materials Science and Engineering: A

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Superelastic NiTi (51.0 at.% Ni) specimens reinforced with 0, 10 and 20 vol.% TiC particles were deformed under uniaxial compression while neutron diffraction spectra were collected. The experiments yielded in-situ measurements of the thermoelastic stress-induced transformation. The evolution of austenite/martensite phase fractions and of elastic strains in the reinforcing TiC particles and the austenite matrix were obtained by Rietveld refinement [1] during the loading cycle as the austenite transforms to martensite (and its subsequent back transformation during unloading). Phase fractions and strains are discussed in terms of load transfer in composites where the matrix undergoes a stress-induced phase transformation.

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Section: Methodsmentioning

confidence: 99%

Stress-induced martensitic transformations in NiTi and NiTi–TiC composites investigated by neutron diffraction

Vaidyanathan

Bourke

Dunand

1999

Materials Science and Engineering: A

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“…This inhomogeneous deformation mode divides a deformed sample into transformed and non-transformed zones; and is in this interface, the phase transformation front, at which the lattice distortion takes place. It is well known that the evolution of the amount of transformation fronts strongly depends on the strain rate, at least for the low strain rate range (Leo et al, 1993;Shaw & Kyriakides, 1995), nevertheless the dynamics of the transformation is unknown when it is induced at impact strain rates.…”

Section: Nucleation and Phase Transformation Front Evolutionmentioning

confidence: 99%

Thermo-Mechanical Behaviour of NiTi at Impact

Zurbitu¹,

Kustov²,

Zabaleta³

et al. 2010

Shape Memory Alloys

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“…The confluence of the forward transformation fronts originates a discontinuity in the crystal lattice which is favourable for the nucleation of reverse SIM transformation. This feature shows that the SIM transformation at impact strain rates is inhomogeneous, similarly to that observed at very low strain rates, 10 -4 s -1 or lower [8,9], and no multiple transformation fronts appear as is observed when strain rate is on the order of 10 -4 -10 -2 s -1 [5]. It is well known that when the deformation is performed at very low strain rates, there is enough time to allow all the transformation heat to be exchanged with the surroundings being the temperature in the sample almost constant.…”

Section: Resultsmentioning

confidence: 60%

“…It is well known that when the deformation is performed at very low strain rates, there is enough time to allow all the transformation heat to be exchanged with the surroundings being the temperature in the sample almost constant. Then, the nucleation only appears at the grips and only one or two fronts appear during SIM transformation [8,9]. Nevertheless when the strain rate is increased, up to 10 -2 s -1 , the number of transformation fronts are multiplied.…”

Section: Resultsmentioning

confidence: 99%

Phase transformation fronts propagation during the stress induced martensitic transformation at impact strain rates in NiTi shape memory alloy wires

Zurbitu

Castillo

Aretxabaleta

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. Propagation of phase transformation fronts during the stress induced martensitic (SIM) transformation at impact strain rates, on the order of 10 s -1 , was observed in situ by measuring changes in infrared radiation on the surface of superelastic NiTi wires. The exothermic/endothermic character of the forward/reverse SIM transformation changes the local temperature making visible the nucleation and propagation of phase transformation fronts. The nucleation during forward SIM transformation usually occurs at both ends of the sample near the grips, where stress concentrations are unavoidable. During unloading, nucleation of the reverse SIM transformation takes place at point where the forward SIM transformation was finished. At impact no more nucleations were observed so that only the phase transformation fronts arising from the mentioned nucleations appear. In the non-transformed zone, the temperature remains similar to that observed for the test in which only the elastic deformation of the austenitic phase occurs. This feature shows that the SIM transformation at impact strain rates is inhomogeneous and, similarly to that observed at very low strain rates, lower than 10 -4 s -1 , when the deformation may be considered as an isothermal process and the temperature in the sample remains almost constant, no multiple transformation fronts appear as is observed when strain rate is on the order of 10 -4 -10 -2 s -1 . For specimens cycled at impact, the nucleation at the beginning of the SIM transformation occurs at several locations and during the deformation more nucleation points arise since the stress necessary to initiate another nucleations is lower than necessary to continue the propagation of the active fronts. These locations are similar for different cycles showing that they do not arise by chance, but rather because there are locations more favourable for the nucleation.

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Transient heat transfer effects on the pseudoelastic behavior of shape-memory wires

Cited by 202 publications

References 6 publications

Stress-induced martensitic transformations in NiTi and NiTi–TiC composites investigated by neutron diffraction

Stress-induced martensitic transformations in NiTi and NiTi–TiC composites investigated by neutron diffraction

Thermo-Mechanical Behaviour of NiTi at Impact

Phase transformation fronts propagation during the stress induced martensitic transformation at impact strain rates in NiTi shape memory alloy wires

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