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Showing 1 to 20 of 24 for “"superelasticity"”.
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Constitutive equations for superelasticity in crystalline shape-memory materials
A crystal-mechanics-based constitutive model for polycrystalline shape-memory materials has been developed. The model has been implemented in a finite-element program. Finite-element calculations of polycrystal response were performed using two methods: (1) The full-finite element method where each …
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Computational modeling of size-dependent superelasticity in shape memory alloys
… range of problems involving size effects in superelasticity with the potential to guide microstructure design and optimization. In particular, the model captures the increase of the stress hysteresis and strain hardening in bulk polycrystalline SMAs for decreasing grain size, as well as the …
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Understanding the formation and influence of the omega phase in metastable beta Ti-Nb based alloys
… to the martensitic α″ phase, enabling superelasticity. However, the inability to control key properties of the transformation prevents industrial uptake, with the presence of the hexagonal ω phase often reported as a primary cause for such challenges. Despite over 70 years active …
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The effect of annealing on the microstructure of Cu-Al-Ni-Mn shape memory alloy microwires
Shape memory alloys exhibit superelasticity and the shape memory effect by undergoing a diffusionless phase transformation between the austenite and martensite phases. Nickel-titanium alloys are currently the most common material used. However, due to their expensive cost, alternatives such as …
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Cu-based shape memory microwires : towards complex structures
… properties of the shape memory effect and superelasticity. Shape memory properties are characterized by the diffusionless phase transformation between austenite and martensite that can be thermally or stress induced. Cu-based shape memory alloys provide an exciting area of research due to …
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Computational Modeling of Elastic and Transformation Incompatibility at Grain Boundaries in Shape Memory Materials
… fields due to their unique properties such as superelasticity and shape memory effect. Desirable superelastic properties of shape memory materials are realized to their maximum extent in single crystalline structures due to the absence of internal constraints. By contrast, in polycrystalline …
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Reduced-Order Modeling and Design Optimization of Thermomechanical Shape Memory Alloy-Based Bistable Microactuators and Hyperelastic Material Systems
… key phenomena such as shape memory effect, superelasticity, and phase transformation. It is applied to simulate an SMA-based bistable microactuator, demonstrating its ability to predict complex coupled behavior and support actuator design. To reduce computational cost, reduced-order modeling …
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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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Grain constraint and size effects in shape memory alloy microwires
… properties, such as the shape memory effect and superelasticity. Among the many alloy families that have been shown to exhibit shape memory properties the ones based on copper are interesting because they are relatively inexpensive and show excellent properties when made as single crystals. …
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Assessing the opportunity to produce Nitinol medical device components using additive manufacturing
… considering Nitinol properties used (superelasticity, shape memory, and ductility) and the opportunity for 3D printing (prototyping, replacing existing Nitinol parts, developing new Nitinol parts). The best opportunities in the short-term for this technology were identified to be …
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Nanoindentation Under Dynamic Conditions
… indentation, the strain rate dependence of the superelasticity of nickel-titanium was probed over a range of temperatures. Similar trends in elastic energy ratios with temperature were observed with the largest elastic proportions occurring at the Austenite finish transformation temperature. …
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Computational framework for simulating the deformation and fracture response of oligocrystalline shape memory alloys
… temperature. Unique features including the superelasticity and shape memory effect have made SMAs attractive materials for a variety of fields ranging from bioengineering to aerospace engineering. In polycrystalline forms, the desirable properties of SMAs have been significantly limited by …
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Processing-surface integrity-fatigue relationship in electrical discharge machining of nitinol shape memory alloy
… properties, i.e., thermal shape memory and superelasticity. Nitinol has broad applications in medical device, aerospace, actuator, machine tool, and civil industries due to its excellent mechanical properties, high fatigue strength, superior corrosion resistance, and good biocompatibility. …
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Developing a new interatomic potential and atomistic study of NiTiHf
… to analyze the influence of precipitates on the superelasticity and shape memory effect of NiTiHf alloy. The results showed that in the presence of H-phase precipitates, the transformation temperatures increase. In addition, the thermal cycling of NiTiHf under constant stress was simulated and it …
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Surface integrity of laser cutting nitinol shape memory alloy
… of superelastic Nitinol. A method of modeling superelasticity and thermal shape memory of Nitinol was developed. (3) A 3-dimensional finite element model of pulsed laser cutting was developed to better understand the process mechanism in laser cutting of Nitinol. A novel thermal loading model …
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Tribological Investigation of Nickel Titanium Shape Memory Alloy (NiTi SMA) Coatings
… SMA) coatings demonstrate shape memory effects, superelasticity and excellent biocompatibility. It has been widely used in various applications such as in dentistry, orthopaedics and micro electro mechanical system. However, the application of NiTi SMA coating in the tribological field is still …
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Atomistic to Continuum Multiscale and Multiphysics Simulation of NiTi Shape Memory Alloy
… deformations are recovered upon heating, and superelasticity (SE), where large strains imposed at high enough temperatures are fully recovered. Phase transformation process in NiTi SMA is a very complex process that involves the competition between developed internal strain and phonon …
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A Mechanistic Understanding of the β to α′′ Transformation in Superelastic Ti-24Nb-4Zr-8Sn (wt%)
Metastable β titanium alloys have potential for application in vibration damping systems, due to their wide mechanical hysteresis and large recoverable strains, arising from a re- versible martensitic transformation between a parent bcc β phase and an orthorhombic α′′ martensite. Of these alloys, …
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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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Modeling mechanical properties – linking atomistics to continuum
… we resolve the mechanistic origin of the NiTi superelasticity. Using a newly developed pair potential, the compressive load/unload behavior of austenitic NiTi (consisting of B2 lattice) is examined. The material is demonstrated to undergo full strain recover upon 5% of straining. The origin of …
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