Beyond the strain recoverability of martensitic transformation in NiTi

Heller, Luděk; Šittner, Petr; Sedlák, Petr; Seiner, Hanuš; Tyc, Ondřej; Kadeřávek, Lukáš; Sedmák, Pavel; Vronka, Marek

doi:10.1016/j.ijplas.2019.01.007

Cited by 96 publications

(40 citation statements)

References 54 publications

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“…Fig. 9 Cyclic superelastic tensile tests (20 cycles) at room temperature 20°C on NiTi wires with different microstructures denoted by pulse times (7,8,10,12,14,15,16,19,20) ms Shap. Mem.…”

Section: Tensile Tests Until Rupture At Various Test Temperaturesmentioning

confidence: 99%

“…5, 6, 7, and 8, which is of main interest for engineering applications of superelastic NiTi wires. To present relevant experimental evidence on that, we have performed cyclic superelastic tensile tests on selected NiTi wires (pulse times (7,8,10,12,14,15,16,18,20) ms) at room temperature (Figs. 9, 10, 11, 12) and on the 12 ms wire at various temperatures (Figs.…”

Section: Cyclic Superelastic Testsmentioning

confidence: 99%

“…10d). After the 5th cycle, the observed density of dislocations became considerably higher and even isolated {114} austenite twins were occasionally found (see [4,7,8] for identification and analysis of the {114} austenite twins in deformed microstructures). After the 20th cycle, when the accumulated unrecovered strain approached nearly 7%, {114} austenite twins became common defects in the microstructure of cyclically deformed 16 ms wire.…”

Section: Cyclic Superelastic Testsmentioning

confidence: 99%

“…As a result, the functional properties of the wire, including the stability of its cyclic superelastic response, change. In fact, this frequently happens during the shape setting of already superelastic wires [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…However, the superelastic NiTi wires exhibit instability of cyclic stress-strain response and related functional and structural fatigue, which represents serious problems for many promising engineering applications. It was linked to the transformation-plasticity coupling in the literature [3][4][5][6][7][8][9][10][11]. In this respect, tensile tests until rupture on NiTi wires have become of interest again.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Tensile Deformation of Superelastic NiTi Wires in Wide Temperature and Microstructure Ranges

Chen

Tyc

Molnárová

et al. 2018

Shap. Mem. Superelasticity

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Superelastic NiTi wires were prepared from a single cold worked wire by various electropulse heat treatments. The wires having a wide range of virgin microstructures were subjected to tensile tests until rupture and cyclic superelastic tensile testing in a wide temperature range. The results were complemented by TEM observation of lattice defects created by superelastic cycling. It appeared that the yield stress depends significantly on the wire microstructure and less on the test temperature. The upper plateau stress varies with the microstructure through its effect on the Ms temperature and increases with increasing temperature in accord with the Clausius-Clapeyron equation up to a maximum temperature characteristic for each microstructure. The upper plateau strains exhibit pronounced maxima (12-18%) at test temperatures and microstructures (pulse times), at which the upper plateau stress approaches the yield stress. The instability of cyclic superelastic deformation was found to be inversely related to the difference between the yield stress and upper plateau stress. Cyclic deformation introduces dislocation slip in the microstructure of the cycled wire from the 3rd cycle and promotes formation of {114} austenite twins upon later cycling. These observations were explained by the activation of deformation twinning in oriented martensite and the stress induced B2 ) B19 0 ) B2 T martensitic transformation in specific range of microstructures and temperatures. The ductility of the tested wires was observed to vary stepwise with microstructure from * 13 up to * 55% and gradually decreased with temperature increasing above 100°C.

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“…Fig. 9 Cyclic superelastic tensile tests (20 cycles) at room temperature 20°C on NiTi wires with different microstructures denoted by pulse times (7,8,10,12,14,15,16,19,20) ms Shap. Mem.…”

Section: Tensile Tests Until Rupture At Various Test Temperaturesmentioning

confidence: 99%

Section: Cyclic Superelastic Testsmentioning

confidence: 99%

Section: Cyclic Superelastic Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tensile Deformation of Superelastic NiTi Wires in Wide Temperature and Microstructure Ranges

Chen

Tyc

Molnárová

et al. 2018

Shap. Mem. Superelasticity

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On behaviors of the shape memory composite containing shape memory polymer matrix and shape memory alloy fibers under uniaxial loading with different temperature conditions

et al. 2021

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The shape memory polymers (SMPs) and shape memory alloys (SMAs), as typical smart materials, have got enormous attention in the fields of aerospace, microsystems, and biomedicine due to their superior shape memory properties. Combining the high strength of SMAs and the large deformation of SMPs, the shape memory polymer composites with the shape memory alloys fibers (SMPC-SMAs) formed by SMP matrix and SMA fibers have the dual advantages of SMAs and SMPs. For the different loading conditions, the mechanical behaviors of the SMPC-SMAs are investigated in this work, by combining with the mechanics of composite materials and the constitutive models of SMPs and SMAs. Compared with the mechanical behavior of pure uniaxial loading, the influence of temperature changes on the phase transition of the material is considered under different constraints. Compared with mechanical behaviors of pure SMAs and pure SMPs, the thermomechanical behaviors of the SMPC-SMAs are discussed and simulated considering the coupling of the phase transition of SMPs and SMAs. And the effects of different fiber content and different pre-strain on the behaviors of such SMPC-SMAs are finally discussed, respectively. The results showed that different mechanical properties for SMPC-SMAs are displayed; such materials not only can maintain the normal shape memory effect but also have the greater strength, which will be a better engineering application prospect.

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Finite element analysis of a prestressed mechanism with multi-antagonistic and hysteretic SMA actuation

Boufayed¹,

Chapelle²,

Destrebecq³

et al. 2020

Meccanica

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This paper deals with the specific hysteretic effects of a multi-antagonistic shapememory alloy (SMA) actuation system in which each wire can be thermally activated individually (one or more at a time). A planar system with six SMA wires organized in a ternary rotational symmetry is studied numerically, via finite element calculation software. The objective is to analyze the functional characteristics of such mechanism, whose response during a thermal activation sequence is multi-antagonistic and hysteretic. Important points are highlighted, such as the avoidance of buckling and plasticity, the possibility of locking a configuration without energy input, and the "attraction" effect of any heating step on the following steps. The feasibility of reaching a given target in the workspace is also illustrated. Finally, the analysis shows the necessity to consider these multi-antagonistic and hysteretic aspects of the actuation in the future design and control of such type of mechanisms. The latter could be of interest as hollow shaft rotary actuators with additional (small) translation degrees of freedom in applications requiring long-term and stable positioning at ambient temperature.

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Beyond the strain recoverability of martensitic transformation in NiTi

Cited by 96 publications

References 54 publications

Tensile Deformation of Superelastic NiTi Wires in Wide Temperature and Microstructure Ranges

Tensile Deformation of Superelastic NiTi Wires in Wide Temperature and Microstructure Ranges

On behaviors of the shape memory composite containing shape memory polymer matrix and shape memory alloy fibers under uniaxial loading with different temperature conditions

Finite element analysis of a prestressed mechanism with multi-antagonistic and hysteretic SMA actuation

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