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Showing 1 to 20 of 41 for “"superelastic"”.
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Design of Superelastic Secondary-Phase-Toughened Alloys
… by designing a multi-phase alloy combining a superelastic phase with a stable elasto-plastic phase. In particular, nano- and micro-scale precipitates, lamellar structures, and bulk matrix morphologies of TiNi are investigated in combination with stable (V,Nb)-Ti matrix phases. These structures …
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The fatigue crack growth behavior of superelastic nickel titanium
… growth phenomena in shape memory alloys under superelastic conditions continues to elude the scientific community: The stress induced martensite phase causes deviations of stress intensity and state at the tip from the classical handbook solutions widely relied on for crack growth …
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Extraction of Superelastic Parameter Values from Instrumented Indentation Data
Interest in superelastic (and shape memory) materials continues to rise, and there is a strong incentive to develop techniques for monitoring of their superelastic characteristics. This is conventionally done via uniaxial testing, but there are many advantages to having a capability for obtaining …
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Superelastic shape memory alloy composite bars for reinforcing concrete structures
Superelastic shape memory alloys (SMAs) are a class of metallic alloys that have the unique property of being able to undergo large amounts of plastic strain while remaining elastic and dissipating energy. This thesis explored a strategy for adding ductility and energy dissipation to FRP …
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Variation of electrical resistance in superelastic NiTi for sensor applications
… displays a constant-temperature property called "superelasticity." A superelastic material is one which can undergo very high reversible strains due to stress-induced change in crystal structure. In the case of Superelastic NiTi, Martensitic transformation occurs. The two crystal structures differ …
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Impact failure modes of graphite epoxy composites with embedded superelastic nitinol
… improved by low volume fractions of embedded superelastic shape memory alloy (SMA) fibers. Graphite/Bismaleimide laminates were embedded with 3% and 6% volume fractions of superelastic nitinol fibers. Quasi-static tests were performed on wide clamped-clamped beams to identify progressive …
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High Loading Oxide Anodes For Lithium Ion Batteries Via A Superelastic Graphene Composite Approach
… OXIDE ANODES FOR LITHIUM ION BATTERIES VIA A SUPERELASTIC GRAPHENE COMPOSITE APPROACH Zhichao Zhang Dr. I-Wei Chen Although nanotechnology has ushered in many new materials storing a high density of electrochemical energy, the performance has only been demonstrated at low material densities, …
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A Mechanistic Understanding of the β to α′′ Transformation in Superelastic Ti-24Nb-4Zr-8Sn (wt%)
… parameters. These are critical to defining the superelastic response and vibration damping potential of the material, which can additionally be shown to vary with both thermal and mechanical cycling. This study aims to rationalise how processing and loading parameters affects different aspects …
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Mechanical properties of superelastic and shape-memory NiTi and NiTi-TiC composites investigated by neutron diffraction
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.
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An investigation into the influence of microstructural condition on the superelastic behaviour in Ti-Nb-based alloys.
Ti-Nb based alloys show superelastic and shape memory properties over a wide range of temperatures, making them attractive for industrial applications. However, within the literature there are significant variations in the reported martensite start temperatures that have not been rationalised. To …
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Energy dissipation in shape memory zirconia particles, packings, and composites
… intersection of two classes of materials, namely superelastic materials and granular materials, each known for their ability to dissipate large amounts of kinetic energy. Because of their energy-absorbing properties, superelastic granular materials are of interest for development into applications …
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The Characterization and Control of Shape Memory Alloy Cables for Reinforcement of Engineered Cementitious Composite Beams
… cementitious composite (ECC) beams using superelastic Nitinol shape memory alloy (SMA) cables. Nitinol is the most popularly used SMA and superelastic Nitinol cable possesses many attractive features, such as large recoverable strain, large load bearing capacity, among others. To …
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In search of martensite : titanium-tantalum shape-memory alloy
… devices that rely on the shape-memory (SME) and superelastic properties of various nickel-based alloys [8]. Unfortunately, there is also serious concern about the toxicity of nickel. Titanium based shape-memory alloys have been noted as potentially non-toxic replacements of the more traditional, …
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Diffraction Studies Of Deformation In Shape Memory Alloys And Selected Engineering Components
… as 8%, which are also recovered and resulting in superelasticity. This work primarily focuses on neutron diffraction measurements during loading at the Los Alamos Neutron Science Center at Los Alamos National Laboratory. Three phenomena were investigated: First, the phenomena of hysteresis …
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Computational modeling of size-dependent superelasticity in shape memory alloys
The superelastic effect in shape memory alloys (SMAs) is attributed to the stress-induced reversible austenitic-martensitic phase transformations. It is characterized by the development of significant strains which are fully recoverable upon unloading, and also characterized by the …
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Constitutive equations for superelasticity in crystalline shape-memory materials
… averages over the entire aggregate. A variety of superelastic experiments were performed on initially-textured Ti-Ni rods and sheets. The predicted stress-strain curves from finite-element calculations are shown to be in good accord with the corresponding experiments. For the Ti-Ni sheet, …
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Ballistic Impact Resistance of Graphite Epoxy Composites With Shape Memory Alloy and Extended Chain Polyethylene Spectra™ Hybrid Components
… studied. The hybrid components tested include superelastic shape memory alloy (SMA), a material having an unusually high stra in to failure (15 - 20%), and a high performance extended chain polyethylene (ECPE) known as Spectra™, a polymer fiber traditionally used in soft and hard body armor …
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Instrumented Nanoindentation Studies Of Deformation In Shape Memory Alloys
… the deformation behavior of the shape memory and superelastic NiTi was obtained for the first time, as opposed to existing qualitative indentation studies. For the case of shape memory NiTi, the elastic modulus of the B19' martensite prior to twinning was determined using spherical indentation to …
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Transmission Electron Microscopy Studies In Shape Memory Alloys
… The stress induced transformation results in the superelastic effect, while the thermally induced transformation is associated with strain recovery that results in the shape memory effect. Ternary elemental additions such as Fe can additionally introduce an intermediate rhombohedral (R) phase …
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Critical stresses for twinning, slip and transformation in shape memory alloys: modeling and experiments
… slip stress that govern shape memory and superelastic behavior in shape memory alloys (SMAs). However, it is a tremendous experimental effort to determine these parameters for multiple alloys. In addition, slip, twinning and transformation events could be activated simultaneously or …
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