&lt;title&gt;Effects of thermomechanical history on the tensile behavior of Nitinol ribbon&lt;/title&gt;

Lach, Cynthia L.; Turner, Travis L.; Taminger, Karen M. B.; Shenoy, R. N.

doi:10.1117/12.474990

“…Although all samples were tested at room temperature, Figure 6 indicates that the stress required for changing TM to DM (in the predominantly M-phase samples) is larger than the stress needed to transform the predominantly R-phase sample to DM. This observation agrees well with experimental results reported by Lach et al (2002) where they compared the stress-strain relationships of 'recovered' ribbons (those cooled to between M s and R f ) with 'recovered frozen' ribbons (cooled below M f ). It is noted that the selection of a NiTi alloy composition with a M f below ambient results in lower antagonistic forces than one with M f near or above ambient.…”

Section: Tensile Test Resultssupporting

confidence: 91%

Two-way Antagonistic Shape Actuation Based on the One-way Shape Memory Effect

Sofla

¹

,

Elzey

²

,

Wadley

³

2008

Journal of Intelligent Material Systems and Structures

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The stress created by the austenite transformation of mechanically constrained NiTi shape memory alloys (SMAs) significantly exceeds that required to deform (detwin) its low temperature martensitic phase. The one-way shape memory effect can therefore be used to create antagonistic, fully reversible flexural shape morphing structures by assembling opposing pairs of linear contractile SMA actuators. These structures possess two distinct inactive configurations, neither of which requires continuous power for shape retention making them potentially suitable for long-term applications. Here, the shape changes of a representative antagonistic flexural unit cell have been experimentally evaluated, and the effect of the pre-strain of near equiatomic NiTi alloys on the actuation strain has been analyzed and discussed. The predicted deformations are then successfully compared to the response of prototype actuators.

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“…Among these properties, the Young's modulus of austenite, the Poisson's ratio and density are same as those in [33], with the Young's modulus of the martensite being half of the austenite. The transformation temperatures are based on DSC test results in [30]. The phase diagram parameters and the max residual strain were not available for the SMA ribbon used in the composite and values were taken from [38; 43; 44] for a similar NiTi material.…”

Section: Clamped Sma Hybrid Composite Beammentioning

confidence: 99%

Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

Gao

¹

,

Burton

²

,

Turner

³

et al. 2006

J. Eng. Mater. Technol.

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The usage of shape memory materials has extended rapidly to many fields, including medical devices, actuators, composites, structures and MEMS devices. For these various applications, shape memory alloys (SMAs) are available in various forms: bulk, wire, ribbon, thin film, and porous. In this work, the focus is on SMA hybrid composites with adaptive-stiffening or morphing functions. These composites are created by using SMA ribbons or wires embedded in a polymeric based composite panel/beam. Adaptive stiffening or morphing is activated via selective resistance heating or uniform thermal loads. To simulate the thermomechanical behavior of these composites, a SMA model was implemented using ABAQUS' user element interface and finite element simulations of the systems were studied. Several examples are presented which show that the implemented model can be a very useful design and simulation tool for SMA hybrid composites.

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“…Extensive experimental and modeling work has also been conducted on active SMA polymer composites by Turner and his collaborators at NASA Langley Research Center [28][29][30][31][32][33]. Figure 1 shows a conceptual airplane with morphing airfoil made of shape memory alloy hybrid composite and the adaptive stiffening prototype beam at NASA undergoing a temperature ramp test.…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis of adaptive-stiffening and shape-control SMA hybrid composites

Gao¹,

Turner

²

,

Burton³

et al. 2005

Self Cite

View full text Add to dashboard Cite

The usage of shape memory materials has extended rapidly to many fields, including medical devices, actuators, composites, structures and MEMS devices. For these various applications, shape memory alloys (SMAs) are available in various forms: bulk, wire, ribbon, thin film, and porous. In this work, the focus is on SMA hybrid composites with adaptive-stiffening or morphing functions. These composites are created by using SMA ribbons or wires embedded in a polymeric based composite panel/beam. Adaptive stiffening or morphing is activated via selective resistance heating or uniform thermal loads. To simulate the thermomechanical behavior of these composites, a SMA model was implemented using ABAQUS' user element interface and finite element simulations of the systems were studied. Several examples are presented which show that the implemented model can be a very useful design and simulation tool for SMA hybrid composites.

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<title>Effects of thermomechanical history on the tensile behavior of Nitinol ribbon</title>

Abstract: Shape memory alloys (SMAs) have enormous potential for a wide variety of applications.

Cited by 5 publications

References 11 publications

Two-way Antagonistic Shape Actuation Based on the One-way Shape Memory Effect

Two-way Antagonistic Shape Actuation Based on the One-way Shape Memory Effect

Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

Finite element analysis of adaptive-stiffening and shape-control SMA hybrid composites

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