Anisotropy of the Shape Memory Effect in Tension of Cold-rolled 50.5 Tı 49.2 Ni (at.%) Sheet

Mulder, J.H.; Thoma, Paul E.; Beyer, J.

doi:10.1515/ijmr-1993-840712

Cited by 5 publications

(6 citation statements)

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“…Even though transformation is inhibited for the TD specimen, there is a small residual strain accumulation, likely due to low Schmid factors for slip. For a similar cold-rolled nickel-titanium TD sheet specimen, Mulder et al found that the possible slip Schmid factors were close to zero [25]. Similarly, Chang and Wu [26] also measured a low accumulation of residual strain in unfavorably textured specimens.…”

Section: Effect Of Crystallographic Texture and Applied Strain Rate O...mentioning

confidence: 91%

“…Crystallographic texture also affects the residual strain accumulation in SMAs, where an unfavorably textured (TD) specimen will exhibit smaller residual strains. Mulder et al [25] explained this smaller accumulation of residual strain in TD specimens (where the tensile axis is parallel to the TD) by calculating the angular dependence of the Schmid factor for slip for the four possible martensite textures corresponding to the same system in the austenite. They found that the Schmid factor for slip of the TD specimen was close to zero for all four of the textures, leading to less accumulated residual strain.…”

Section: Effect Of Texturementioning

confidence: 99%

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The effect of texture on stress-induced martensite formation in nickel–titanium

Kim

Daly

2013

Smart Mater. Struct.

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An experimental study was performed to investigate the effect of texture on stress-induced martensitic phase transformation in the shape memory alloy Nickel-Titanium (Nitinol). Thin sheet specimens of Nitinol were examined under uniaxial tensile loading using three-dimensional digital image correlation in order to spatially and temporally track strain localization indicative of martensitic transformation. Tensile specimens were fabricated along directions oriented 0° (RD), 45°, and 90° (TD) to the rolling direction of the sheet and subjected to 50 cycles at prescribed strain rates of-4-3-2-1 g ε = 10 ,10 , and 10 s. It was found that upon loading, specimens unfavorably oriented for transformation (TD specimens) nucleated a greater number of deformation bands due to a smaller difference between nucleation and propagation stresses, and also accommodated less axial strain inside the band and more axial strain outside of the band. The unfavorable (TD) specimens also exhibited a stronger cycle-to-cycle similarity in the strain accommodated inside the deformation band, which has important implications for the design of SMA structures for fatigue applications. Finally, the (primarily martensite) region of the deformation band(s) consistently showed significantly stronger cycle-to-cycle similarity than the (primarily austenite) region outside of the band(s), regardless of specimen texture.

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Section: Effect Of Crystallographic Texture and Applied Strain Rate O...mentioning

confidence: 91%

Section: Effect Of Texturementioning

confidence: 99%

The effect of texture on stress-induced martensite formation in nickel–titanium

Kim

Daly

2013

Smart Mater. Struct.

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“…If a textured SMA sheet or thin foil is used, tension along the rolling direction provides much better performance than tension along the transverse direction. This is due to the deformation and shape recovery anisotropy due to texture distribution, see for example [36][37][38]. (3) Train the SMA to have TWME so that the work done on deforming the bias component is minimized.…”

Section: Discussion Of the Estimated Thermal Efficiencymentioning

confidence: 99%

The work production of shape memory alloy

Liu

2004

Smart Mater. Struct.

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This paper is to evaluate the work production and thermal efficiency of shape memory alloy (SMA). NiTi wire under pure tension mode is chosen for the work production and several bias components are evaluated including a linear elastic component, a non-linear superelastic SMA wire and an SMA with well developed two-way memory effect (TWME). The calculated thermal efficiency shows good agreement with the reported experimental data. The estimation of the thermal efficiency is further discussed with respect to the latest results on SMAs, especially the transformation enthalpy change. Ways of increasing both the work production and the thermal efficiency of SMAs are further suggested.

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“…The Rphase crystal structure can be thought of as a rhombohedral distortion along the [111] direction of the B2 parent lattice; the R-phase is often described by a hexagonal unit cell with lattice parameters of a = 0.738 and c = 0.532 nm [44]. It is not completely understood why the R-phase appears in certain TiNi specimens; however, various processing conditions such as cold working, thermal annealing, thermal cycling, variation of Ni content and introduction of ternary elements can bring about its occurrence [44][45][46][47]. Since the SME associated with the R-phase transformation is limited to less than 1% recoverable strain [48], the austenite to rhombohedral phase transformation is not as effective for actuator applications as the austenite to monoclinic phase transformation.…”

Section: The Titanium-nickel Shape-memory Alloymentioning

confidence: 99%

The TiNi shape-memory alloy and its applications for MEMS

Kahn

Huff

Heuer

1998

J. Micromech. Microeng.

257

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The shape-memory effect is a solid state phenomenon which exploits a reversible phase transformation to repeatedly achieve an initial shape, even after some deformation of the material. Numerous metal alloys exhibit this effect. One of the most widely used shape-memory alloys is TiNi, due to its large range of recoverable deformations and its relative ease of processing. In bulk and wire form, TiNi has been applied to a number of applications, and as a thin film, TiNi is an excellent material for use as a microactuator in microelectromechanical systems (MEMS), due to its large recovery forces and high recoverable strains. Several TiNi-actuated MEMS devices have already been reported.

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Anisotropy of the Shape Memory Effect in Tension of Cold-rolled 50.5 Tı 49.2 Ni (at.%) Sheet

Cited by 5 publications

References 0 publications

The effect of texture on stress-induced martensite formation in nickel–titanium

The effect of texture on stress-induced martensite formation in nickel–titanium

The work production of shape memory alloy

The TiNi shape-memory alloy and its applications for MEMS

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