On the origin of residual strain in shape memory alloys: experimental investigation on evolutions in the microstructure of CuAlBe during complex thermomechanical loadings

Barati, Mahmoud; Chirani, Shabnam Arbab; Kadkhodaei, Mahmoud; Saint‐Sulpice, Luc; Calloch, Sylvain

doi:10.1088/1361-665x/aa5745

Cited by 9 publications

(8 citation statements)

References 37 publications

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“…Our proposed model further assumes a constant material characteristic which neglects plastic strain and wear phenomena. Actual NiTi alloy, however, exhibits growing residual strain and degrading transformation stress which goes along with a change in the shape of the stress-straincharacterisitc, as examined for example in [25]. These effects also manifest in the considered bending experiments.…”

Section: By Applying the Substitutionmentioning

confidence: 84%

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On the influence of pseudoelastic material behaviour in planar shape-memory tubular continuum structures

Greiner-Petter

Sattel

2017

Smart Mater. Struct.

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For planar tubular continuum structures based on precurved shape memory alloy tubes a beam model with respect to the pseudoelastic material behaviour of NiTi is derived. Thereunto a constitutive material law respecting tension-compression asymmetry as well as hysteresis is used. The beam model is then employed to calculate equilibrium curvatures of concentric tube assemblies without clearance between the tubes. In a second step, the influence of clearance is approximated to account for non-concentric tube assemblies. These elastokinematic results are integrated into a purely kinematic model to describe the cannula path under the presence of material hysteresis and clearance. Finally a photogrammetric measurement system is used to track the path of an exemplary two-tube continuum structure to examine the accuracy of the proposed model. It is shown that material hysteresis leads to a hysteresis phenomena in the path of the tubular continuum structure.

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Section: By Applying the Substitutionmentioning

confidence: 84%

“…is used to rotate frame j p , 1 into j p , by the angle L j p j p , , j k = ¯. The combination of (25) and (26) gives the subsection transformation…”

Section: Kinematics Of Tubular Continuum Structuresmentioning

confidence: 99%

On the influence of pseudoelastic material behaviour in planar shape-memory tubular continuum structures

Greiner-Petter

Sattel

2017

Smart Mater. Struct.

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“…From the constant volume assumption (Eq. 3a) [9] and the strain formula (Eq. 3b), the relative change ratio of electrical resistivity is inferred as Eq.…”

Section: Fig 2 Schematic Diagram Of the Calculation Of Linearity And ...mentioning

confidence: 99%

Effects of cold-drawing and low-temperature annealing on the sensing properties of NiTi alloys

2023

Materials Research Proceedings

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Abstract. As an intelligent material, NiTi alloy exhibits shape memory effect and superelasticity. Its electrical resistance varies with deformation, thus making NiTi alloy a potential sensing material. Linearity and sensitivity are the two principal characteristics of sensors. Linearity reveals the deviation of the actual resistance-strain response from an ideal straight line and sensitivity is the change in input required to generate a unit change in output. Though conventional polycrystalline NiTi alloys possess high sensitivity and large strain range, the non-linear resistance-strain responses were not negligible thus hindering their sensing application. It was found that cold-drawing combing with low-temperature annealing had affected the linearity, while the influence rules were not clear. The electrical resistance of the fabricated NiTi alloy wires with various areal reductions were measured during stretching, and the results shown that the cold-drawn and annealed NiTi alloys exhibited better linearity though with decreased sensitivity. This investigation provides foundation for subsequent research on improving or tailoring the sensing properties of NiTi alloys.

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“…Different investigation methods are employed to analyze the kinetics and interactions at different scale levels. The most implemented techniques are the observations of the microstructure by transmission electron microscopy (TEM) [5,6,9,16], high-energy x-ray diffraction [5,8] or in-situ electric resistivity [17][18][19][20][21]. The amount of data provided by each of these methods varies a lot, as well as the cost of their usage.…”

Section: Introductionmentioning

confidence: 99%

Electric resistivity evolution in NiTi alloys under thermomechanical loading: phase proportioning, elasticity and plasticity effects

JÚNIOR

Pino

Barati

et al. 2023

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The well-known Martensitic transformation is the main feature for almost all Shape Memory Alloys (SMA) usage. Meanwhile, the practical implementation of SMA in devices is not straightforward due to the evolution of their functional properties in operation. This evolution is mainly due to the different interactions between the martensite transformation (MT) or detwinning (DT) and mechanisms such as plasticity. Although these mechanisms are extensively studied by fine and precise techniques (e.g., high energy X-ray diffraction and transmission electron microscopy), their impact on a macroscopic level (usage scale) are not fully clarified. In this work, the effects of some of the most influential mechanisms in a NiTi alloy are investigated by using electric resistivity measurements at macroscopic scale. Distinct phase proportioning approaches are employed to analyze the martensitic transformation kinetic. It is found that, unlike elastic strains, plastic strains are a key influential factor on resistivity variations in SMAs. It is also shown that the use of an assumption of linearity between fraction of stress-induced martensite and strain transformation can lead to unrealistic interpretations of transformation mechanisms in NiTi wires.

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On the origin of residual strain in shape memory alloys: experimental investigation on evolutions in the microstructure of CuAlBe during complex thermomechanical loadings

Cited by 9 publications

References 37 publications

On the influence of pseudoelastic material behaviour in planar shape-memory tubular continuum structures

On the influence of pseudoelastic material behaviour in planar shape-memory tubular continuum structures

Effects of cold-drawing and low-temperature annealing on the sensing properties of NiTi alloys

Electric resistivity evolution in NiTi alloys under thermomechanical loading: phase proportioning, elasticity and plasticity effects

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