Academic literature on the topic 'High strength shape memory alloy'

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Journal articles on the topic "High strength shape memory alloy"

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Feng, Xue, Li Min Zhao, and Xu Jun Mi. "Characristics of Shape Memory Composites Combined with Shape Memory Alloy and Shape Memory Polymer." Advanced Materials Research 705 (June 2013): 169–72. http://dx.doi.org/10.4028/www.scientific.net/amr.705.169.

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In order to develop high functionality of shape memory materials, the shape memory composites combined with TiNi wire and shape memory epoxy were prepared, and the mechanical and thermomechanical properties were studied. The results showed the addition of TiNi wire increased the Young modulus and breaking strength both at room temperature and at elevated temperature. The composites maintained the rates of shape fixity and shape recovery close to 100%. The maximum recovery stress increased with increasing TiNi wire volume fraction, and obtained almost 3 times of the matrix by adding 1vol% TiNi wire.
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Hua, Peng, Minglu Xia, Yusuke Onuki, and Qingping Sun. "Nanocomposite NiTi shape memory alloy with high strength and fatigue resistance." Nature Nanotechnology 16, no. 4 (2021): 409–13. http://dx.doi.org/10.1038/s41565-020-00837-5.

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Karaca, H. E., I. Kaya, H. Tobe, et al. "Shape memory behavior of high strength Ni54Ti46 alloys." Materials Science and Engineering: A 580 (September 2013): 66–70. http://dx.doi.org/10.1016/j.msea.2013.04.102.

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Li, D. S., X. P. Zhang, Z. P. Xiong, and Y. W. Mai. "Lightweight NiTi shape memory alloy based composites with high damping capacity and high strength." Journal of Alloys and Compounds 490, no. 1-2 (2010): L15—L19. http://dx.doi.org/10.1016/j.jallcom.2009.10.025.

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Saghaian, S. M., H. E. Karaca, H. Tobe, et al. "High strength NiTiHf shape memory alloys with tailorable properties." Acta Materialia 134 (August 2017): 211–20. http://dx.doi.org/10.1016/j.actamat.2017.05.065.

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Karaca, H. E., E. Acar, G. S. Ded, et al. "Shape memory behavior of high strength NiTiHfPd polycrystalline alloys." Acta Materialia 61, no. 13 (2013): 5036–49. http://dx.doi.org/10.1016/j.actamat.2013.04.039.

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Lee, Hao-Chen, Yue-Jin Chen, and Chih-Hsuan Chen. "Effect of Solution Treatment on the Shape Memory Functions of (TiZrHf)50Ni25Co10Cu15 High Entropy Shape Memory Alloy." Entropy 21, no. 10 (2019): 1027. http://dx.doi.org/10.3390/e21101027.

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This study investigated the effects of solution treatment at 1000 °C on the transformation behaviors, microstructure, and shape memory functions of a novel (TiZrHf)50Ni25Co10Cu15 high entropy shape memory alloy (HESMA). The solution treatment caused partial dissolution of non-oxygen-stabilized Ti2Ni-like phase. This phenomenon resulted in the increment of (Ti, Zr, Hf) content in the matrix and thus increment of the Ms and Af temperatures. At the same time, the solution treatment induced a high entropy effect and thus increased the degree of lattice distortion, which led to increment of the friction force during martensitic transformation, resulting in a broad transformation temperature range. The dissolution of the Ti2Ni-like phase also improved the functional performance of the HESMA by reducing its brittleness and increasing its strength. The experimental results presented in this study demonstrate that solution treatment is an effective and essential way to improve the functional performance of the HESMA.
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Gholampour, A., and T. Ozbakkaloglu. "Confinement of NORMAL- AND HIGH-STRENGTH CONCRETE by Shape Memory Alloy (SMA) Spirals." IOP Conference Series: Materials Science and Engineering 301 (January 2018): 012056. http://dx.doi.org/10.1088/1757-899x/301/1/012056.

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Coughlin, D. R., L. Casalena, F. Yang, R. D. Noebe, and M. J. Mills. "Microstructure–property relationships in a high-strength 51Ni–29Ti–20Hf shape memory alloy." Journal of Materials Science 51, no. 2 (2015): 766–78. http://dx.doi.org/10.1007/s10853-015-9400-7.

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Chung, C. Y., C. L. Chu, and S. D. Wang. "Porous TiNi shape memory alloy with high strength fabricated by self-propagating high-temperature synthesis." Materials Letters 58, no. 11 (2004): 1683–86. http://dx.doi.org/10.1016/j.matlet.2003.10.045.

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Dissertations / Theses on the topic "High strength shape memory alloy"

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Toker, Guher P. "CHARACTERIZATION OF THE SHAPE MEMORY BEHAVIOR OF HIGH STRENGTH NiTiHfPd SHAPE MEMORY ALLOYS." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/114.

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NiTiHf alloys have emerged as potential materials for applications requiring high transformation temperatures (> 100 °C) with high strength and work output. Although they have high transformation temperatures, their low damping capacity, brittleness and poor superelastic responses (of Ti-rich NiTiHf) impedes their wider usage in many industrial applications. In this study, the quaternary alloying element of Pd has been added to NiTiHf alloys to improve and tailor their shape memory behavior,. NiTiHfPd alloys were systematically examined regarding the composition and heat treatments effects. Effects of substituting Hf with Ti on the shape memory behavior of NiTHfPd alloys were investigated. There compositions were selected as Ni40.3Ti34Hf20Pd5 Ni40.3Ti39.7Hf15Pd5 and Ni40.3Ti44.7Hf10Pd5 (at.%). Their transformation temperatures, microstructure and shape memory properties were revealed and compared with conventional shape memory alloys. It was revealed that their transformation temperatures increases but transformation strain decreases with the increment of Hf content. Additionally, superelastic responses of Ni45.3Ti29.7Hf20Pd5 andNi45.3Ti39.7Hf10Pd5 alloys were investigated. Transformation temperatures of polycrystalline Ni45.3Ti29.7Hf20Pd5are highly dependent on aging temperatures and they can be altered widely from room temperature to 250 oC. Finally, the damping capacity of the Ni45.3Ti39.7Hf10Pd5 polycrystal and [111]-oriented Ni45.3Ti29.7Hf20Pd5 single crystal were investigated. The damping capacities were found to be 16-25 J.cm-3, and 10-23 J.cm-3 for the Ni45.3Ti39.7Hf10Pd5 and [111]-oriented Ni45.3Ti29.7Hf20Pd5 alloys, respectively.
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Saghaian, Sayed M. "SHAPE MEMORY BEHAVIOR OF SINGLE CRYSTAL AND POLYCRYSTALLINE Ni-RICH NiTiHf HIGH TEMPERATURE SHAPE MEMORY ALLOYS." UKnowledge, 2015. http://uknowledge.uky.edu/me_etds/65.

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NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing. Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, Ni51.2Ti28.8Hf20, and Ni52Ti28Hf20 (at. %)) were systematically characterized in the furnace cooled condition. H-phase precipitates were formed during furnace cooling in compositions with greater than 50.3Ni and the driving force for nucleation increased with Ni content. Alloy strength increased while recoverable strain decreased with increasing Ni content due to changes in precipitate characteristics. The effects of the heat treatments on the transformation characteristics and microstructure of the Ni-rich NiTiHf shape memory alloys have been investigated. Transformation temperatures are found to be highly annealing temperature dependent. Generation of nanosize precipitates (~20 nm in size) after three hours aging at 450 °C and 550 °C improved the strength of the material, resulting in a near perfect dimensional stability under high stress levels (> 1500 MPa) with a work output of 20–30 J cm– 3. Superelastic behavior with 4% recoverable strain was demonstrated at low and high temperatures where stress could reach to a maximum value of more than 2 GPa after three hours aging at 450 and 550 °C for alloys with Ni great than 50.3 at. %. Shape memory properties of polycrystalline Ni50.3Ti29.7Hf20 alloys were studied via thermal cycling under stress and isothermal stress cycling experiments in tension. Recoverable strain of ~5% was observed for the as-extruded samples while it was decreased to ~4% after aging due to the formation of precipitates. The aged alloys demonstrated near perfect shape memory effect under high tensile stress level of 700 MPa and perfect superelasticity at high temperatures up to 230 °C. Finally, the tensioncompression asymmetry observed in NiTiHf where recoverable tensile strain was higher than compressive strain. The shape memory properties of solutionized and aged Ni-rich Ni50.3Ti29.7Hf20 single crystals were investigated along the [001], [011], and [111] orientations in compression. [001]-oriented single crystals showed high dimensional stability under stress levels as high as 1500 MPa in both the solutionized and aged conditions, but with transformation strains of less than 2%. Perfect superelasticity with recoverable strain of more than 4% was observed for solutionized and 550 °C-3h aged single crystals along the [011] and [111] orientations, and general superelastic behavior was observed over a wide temperature range. The calculated transformation strains were higher than the experimentally observed strains since the calculated strains could not capture the formation of martensite plates with (001) compound twins.
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Kaya, Irfan. "SHAPE MEMORY BEHAVIOR OF SINGLE AND POLYCRYSTALLINE NICKEL RICH NICKEL TITANIUM ALLOYS." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/37.

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NiTi is the most commonly used shape memory alloy (SMA) and has been widely used for bio-medical, electrical and mechanical applications. Nickel rich NiTi shape memory alloys are coming into prominence due to their distinct superelasticity and shape memory properties as compared to near equi-atomic NiTi shape memory alloys. Besides, their lower density and higher work output than steels makes these alloys an excellent candidate for aerospace and automotive industry. Shape memory properties and phase transformation behavior of high Ni-rich Ni54Ti46 (at.%) polycrystals and Ni-rich Ni51Ti49 (at.%) single-crystals are determined. Their properties are sensitive to heat treatments that affect the phase transformation behavior of these alloys. Phase transformation properties and microstructure were investigated in aged Ni54Ti46 alloys with differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) to reveal the precipitation characteristics and R-phase formation. It was found that Ni54Ti46 has the ability to exhibit perfect superelasticity under high stress levels (~2 GPa) with 4% total strain after 550°C-3h aging. Stress independent R-phase transformation was found to be responsible for the change in shape memory behavior with stress. The shape memory responses of [001], [011] and [111] oriented Ni51Ti49 single-crystals alloy were reported under compression to reveal the orientation dependence of their shape memory behavior. It has been found that transformation strain, temperatures and hysteresis, Classius-Clapeyron slopes, critical stress for plastic deformation are highly orientation dependent. The effects of precipitation formation and compressive loading at selected temperatures on the two-way shape memory effect (TWSME) properties of a [111]-oriented Ni51Ti49 shape memory alloy were revealed. Additionally, aligned Ni4Ti3 precipitates were formed in a single crystal of Ni51Ti49 alloy by aging under applied compression stress along the [111] direction. Formation of a single family of Ni4Ti3 precipitates were exhibited significant TWSME without any training or deformation. When the homogenized and aged specimens were loaded in martensite, positive TWSME was observed. After loading at high temperature in austenite, the homogenized specimen did not show TWSME while the aged specimen revealed negative TWSME.
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Acar, Emre. "PRECIPITATION, ORIENTATION AND COMPOSITION EFFECTS ON THE SHAPE MEMORY PROPERTIES OF HIGH STRENGTH NiTiHfPd ALLOYS." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/40.

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NiTiHf high temperature shape memory alloys are attractive due to their high operating temperatures (>100 oC) and acceptable transformation strain compared to NiTi. However, NiTiHf has limitations due to their lack of ductility and low strength, resulting in poor shape memory properties. In this study, Pd has been added to NiTiHf alloys in an attempt to improve their shape memory behavior. A combined approach of quaternary alloying and precipitation strengthening was used. The characterization of a Ni45.3Ti29.7Hf20Pd5 (at. %) polycrystalline alloy was performed in compression after selected aging treatments. Transmission electron microscopy was used to reveal the precipitation characteristics. Differential scanning calorimetry, load-biased (constant stress) thermal cycling experiments and isothermal stress cycling (superelasticity) tests were utilized to investigate the effects of aging temperature and time. The crystal structure and lattice parameters were determined from X-ray diffraction analysis. Significant improvement in the shape memory properties of Ni45.3Ti29.7Hf20Pd5 was obtained through precipitation strengthening. The effects of chemical composition (effects of Hf content replacing with Ti) on the shape memory properties of NiTiHfPd alloys were also revealed. Orientation dependence of the shape memory properties in aged Ni45.3Ti29.7Hf20Pd5 single crystals were investigated along the [111], [011] and [-117] orientations. The shape memory properties were determined to be strong functions of orientation and aging condition. A perfect superelastic behavior (with no irrecoverable strain) with 4.2 % recoverable compressive strain was obtained in the solutionized condition at stress levels as high as 2.5 GPa while 2 % shape memory strain under a bias stress of 1500 MPa was possible in an aged [111] oriented single crystal. A mechanical hysteresis of 1270 MPa at -30 oC, which is the largest mechanical hysteresis that the authors are aware of in the SMA literature, was observed along the [111] orientation. Finally, thermodynamic analyses were conducted to reveal the relationships between microstructure (e.g. precipitate size and interparticle distances) and martensitic transformations in Ni45.3Ti29.7Hf20Pd5 SMAs. Precipitate characteristics were found to be effective on the elastic energies for nucleation, propagation with dissipation energy and these energies influenced the TTs and the constant stress shape memory properties in Ni45.3Ti29.7Hf20Pd5 alloys.
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Simon, Anish Abraham. "Shape memory response and microstructural evolution of a severe plastically deformed high temperature shape memory alloy (NiTiHf)." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/3139.

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NiTiHf alloys have attracted considerable attention as potential high temperature Shape Memory Alloy (SMA) but the instability in transformation temperatures and significant irrecoverable strain during thermal cycling under constant stress remains a major concern. The main reason for irrecoverable strain and change in transformation temperatures as a function of thermal cycling can be attributed to dislocation formation due to relatively large volume change during transformation from austenite to martensite. The formation of dislocations decreases the elastic stored energy, and during back transformation a reduced amount of strain is recovered. All these observations can be attributed to relatively soft lattice that cannot accommodate volume change by other means. We have used Equal Channel Angular Extrusion (ECAE), hot rolling and marforming to strengthen the 49.8Ni-42.2Ti-8Hf (in at. %) material and to introduce desired texture to overcome these problems in NiTiHf alloys. ECAE offers the advantage of preserving billet cross-section and the application of various routes, which give us the possibility to introduce various texture components and grain morphologies. ECAE was performed using a die of 90º tool angle and was performed at high temperatures from 500ºC up to 650ºC. All extrusions went well at these temperatures. Minor surface cracks were observed only in the material extruded at 500 °C, possibly due to the non-isothermal nature of the extrusion. It is believed that these surface cracks can be eliminated during isothermal extrusion at this temperature. This result of improved formability of NiTiHf alloy using ECAE is significant because an earlier review of the formability of NiTiHf using 50% rolling reduction concluded that the minimum temperature for rolling NiTi12%Hf alloy without cracks is 700°C. The strain level imposed during one 90° ECAE pass is equivalent to 69% rolling reduction. Subsequent to ECAE processing, a reduction in irrecoverable strain from 0.6% to 0.21% and an increase in transformation strain from 1.25% to 2.18% were observed at a load of 100 MPa as compared to the homogenized material. The present results show that the ECAE process permits the strengthening of the material by work hardening, grain size reduction, homogeneous distribution of fine precipitates, and the introduction of texture in the material. These four factors contribute in the increase of stability of the material. In this thesis I will be discussing the improvement of mechanical behavior and stability of the material achieved after various passes of ECAE.
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Patman, Andrew J. "High strain rate properties of a near equi-atomic NiTi shape memory alloy." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/14565.

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The effects of strain rate and testing temperature on the mechanical response of a near equi-atomic NiTi alloy have been investigated. All experiments have been conducted in compression, at testing temperatures of room .temperature (-20°C), 30°C, 40°C and 50°C. Quasi-static experiments were performed using a Hounsfield HK50 universal testing machine, and high strain rate measurements were obtained using the split Hopkinson pressure bar technique. The primary differences in the behaviour of the material within these deformation rate regimes appeared to be the presence of a possible transformation inhibition mechanism that occurs for high rates of strain, which manifests itself as an accommodation of applied load after the onset of transformation, increased strain rate sensitivity at high rates, and temperature dependence not evident at low rates. Initial material characterisation was achieved' through microhardness testing, DSC, DMTA, X-ray and electron diffraction, resulting in clarification of the transformation temperatures, martensitic volume fraction and microstructure of the alloy. A post experiment X -ray investigation was also performed in order to establish the microstructural response of the material to deformation. From the stress-strain data collected, the strain rate sensitivity and entropy of transformation of the alloy have been calculated. The application of a standard Arrhenius type equation has also been attempted, in order to estimate the material parameters of activation volume, and the free energy of transformation in the absence of stress. This model was found to be reasonably representative of the response of the alloy, although the results calculated demonstrated a high degree of intrinsic error.
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Nicholson, Douglas E. "Thermomechanical behavior of high-temperature shape memory alloy Ni-Ti-Pd-Pt actuators." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4814.

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To date the commercial use of shape memory alloys (SMAs) has been mostly limited to binary NiTi alloys with transformation temperatures approximately in the -100 to 100 &"186;C range. In an ongoing effort to develop high-temperature shape memory alloys (HTSMAs), ternary and quaternary additions are being made to binary NiTi to form NiTi-X (e.g., X: Pd, Pt, Au and Hf) alloys. Stability and repeatability can be further increased at these higher temperatures by limiting the stress, but the tradeoff is reduced work output and stroke. However, HTSMAs operating at decreased stresses can still be used effectively in actuator applications that require large strokes when used in the form of springs. The overall objective of this work is to facilitate the development of HTSMAs for use as high-force actuators in active/adaptive aerospace structures. A modular test setup was assembled with the objective of acquiring stroke, stress, temperature and moment data in real time during joule heating and forced convective cooling of Ni19.5Ti50.5Pd25Pt5 HTSMA springs. The spring actuators were evaluated under both monotonic axial loading and thermomechanical cycling. The role of rotational constraints (i.e., by restricting rotation or allowing for free rotation at the ends of the springs) on stroke performance was also assessed. Recognizing that evolution in the material microstructure results in changes in geometry and vice versa in HTSMA springs, the objective of the present study also included assessing the contributions from the material microstructural evolution, by eliminating contributions from changes in geometry, to overall HTSMA spring performance. The finite element method (FEM) was used to support the analytical analyses and provided further insight into the behavior and heterogeneous stress states that exist in these spring actuators. Furthermore, with the goal of improving dimensional stability there is a need to better understand the microstructural evolution in HTSMAs that contributes to irrecoverable strains. Towards this goal, available Ni29.5Ti50.5Pd20 neutron diffraction data (from a comparable HTMSA alloy without the solid solution strengthening offered by the Pt addition) were analyzed. The data was obtained from in situ neutron diffraction experiments performed on Ni29.5Ti50.5Pd20 during compressive loading while heating/cooling, using the Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory. Specifically, in this work emphasis was placed on neutron diffraction data analysis via Rietveld refinement and capturing the texture evolution through inverse pole figures. Such analyses provided quantitative information on the evolution of lattice strain, phase volume fraction (including retained martensite that exists above the austenite finish temperature) and texture (martensite variant reorientation and detwinning) under temperature and stress. Financial support for this work from NASA's Fundamental Aeronautics Program Supersonics Project (NNX08AB51A), Subsonic Fixed Wing Program (NNX11AI57A) and the Florida Center for Advanced Aero-Propulsion (FCAAP) is gratefully acknowledged. It benefited additionally from the use of the Lujan Neutron Scattering Center at Los Alamos National Laboratory, which is funded by the Office of Basic Energy Sciences (Department of Energy) and is operated by Los Alamos National Security LLC under DOE Contract DE-AC52-06NA25396.<br>ID: 030646204; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.A.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 102-106).<br>M.S.A.E.<br>Masters<br>Mechanical and Aerospace Engineering<br>Engineering and Computer Science<br>Aerospace Engineering; Space System Design and Engineering Track
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Gu, Xiaojun. "Optimization of Shape Memory Alloy Structures with Respect to Fatigue." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLY012/document.

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Cette thèse présente une approche globale d’optimisation vis-à-vis de la fatigue des matériaux et structures en alliages à mémoire de forme (AMF). Cette approche s’articule en trois étapes : i) Le développement d’une loi de comportement capable de prédire la réponse thermomécanique à l’état stabilisé d’une structure en AMF sous chargement cyclique multiaxial non proportionnel. On prend notamment en compte la dépendance de la déformation résiduelle par rapport à la température. Par ailleurs, la méthode LATIN à grand incrément de temps a été généralisée pour les AMF dans le cadre du modèle ZM. Ceci permet de résoudre les problèmes de convergence numérique rencontrés lorsque le processus de transformation de phase se produit avec une pente du plateau de transformation faible. ii) Le développement d’un critère de fatigue à grand nombre de cycles pour les AMF. Ce critère s’inscrit dans le cadre de la théorie d’adaptation à l’instar du critère de Dang Van pour les métaux élasto-plastiques. Le critère proposé permet de calculer en chaque point de la structure en AMF un facteur de fatigue indiquant son degré de dangerosité. iii) Le développement d’une approche d’optimisation structurale qui peut être utilisée pour améliorer la durée de vie en fatigue prédite par le critère proposé dans la deuxième partie. Des exemples numériques sont traités pour valider chaque étape. L‘approche globale a par ailleurs été testée et validée pour l’optimisation structurale d’un stent<br>This thesis presents a comprehensive and effi cient structural optimization approach for shape memory alloys (SMAs) with respect to fatigue. The approach consists of three steps: First, the development of a suitable constitutive model capable of predicting, with good accuracy, the stabilized thermomechanical stress state of a SMA structure subjected to multiaxial nonproportional cyclic loading. The dependence of the saturated residual strain on temperature and loading rate is discussed. In order to overcome numerical convergence problems in situations where the phase transformation process presents little or no positivehardening, the large time increment method (LATIN) is utilized in combination with the ZM (Zaki-Moumni) model to simulate SMA structures instead of conventional incremental methods. Second, a shakedown-based fatigue criterion analogous to the Dang Van model for elastoplastic metals is derived for SMAs to predict whether a SMA structure subjected to high-cycle loading would undergo fatigue. The proposed criterion computes a fatigue factor at each material point, indicating its degree of safeness with respect to high-cycle fatigue. Third, a structural optimization approach, which can be used to improve the fatigue lifetime estimated using the proposed fatigue criterion is presented. The prospects of this work include the validation of the optimization approach with experimental data
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Lu, Xuemei 1970. "A systems approach to modelling and design of high strain shape memory alloy actuators /." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28000.

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A simulator is developed to model and design high strain shape memory alloy (SMA) tension actuators. The simulator may be used to predict characteristics of a given actuator, or to design its geometry under specifications such as force, speed, stroke and size. The accuracy of the model is verified experimentally in reference to an existing NiTi shape memory alloy prototype actuator. Having developed some confidence in the model, the performance of the proposed actuation mechanism is compared to other existing technologies. In particular, the force-displacement and speed characteristics of a micro-solenoid electro-magnetic actuator and a muscle-size pneumatic actuator are compared to those of the SMA actuators with same dimensions.<br>A new concept of designing shape memory alloy bending actuator is presented in the end of the thesis. Part of the modelling work is accomplished in this research by developing a software simulator which is capable of predicting the geometric transformation of the actuator during bending. As a result, the dynamic strain of each SMA fiber in the actuator can be computed given a bending axis and angle. Graphical display of the bending transformation is implemented using in house software package. Further investigation of modelling and control of the SMA bending actuator is left as future work.
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Lu, Xuemei. "A systems approach to modelling and design of high strain shape memory alloy actuators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37267.pdf.

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Book chapters on the topic "High strength shape memory alloy"

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Saedi, Soheil, Farzad S. Dizaji, Osman E. Ozbulut, and Haluk E. Karaca. "Structural Vibration Control Using High Strength and Damping Capacity Shape Memory Alloys." In Conference Proceedings of the Society for Experimental Mechanics Series. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54777-0_32.

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Senkov, O. N., A. P. Druschitz, S. V. Senkova, K. L. Kendig, and J. Griffin. "Ultra-High Strength Sand Castings from Aluminum Alloy 7042." In Shape Casting. John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118062050.ch24.

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Qifei, Zheng, Xie Shuisheng, and Yuan Guanshen. "Fabrication of TiNiCu Shape Memory Alloy from Elemental Powders." In High Performance Metallic Materials for Cost Sensitive Applications. John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118788028.ch20.

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Tomozawa, M., K. Okutsu, Hee Young Kim, and Shuichi Miyazaki. "Characterization of High-Speed Microactuator Utilizing Shape Memory Alloy Thin Films." In Materials Science Forum. Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.2037.

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Wang, Lei, Toshiro Kobayashi, Y. Harada, and Koichi Tsuchiya. "Fracture Behavior of a Shape Memory Alloy at High Loading Velocity and High Temperature." In Materials Science Forum. Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.4191.

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Lopez, Gabriel A., Mariano Barrado, Eduardo H. Bocanegra, Jose M. San Juan, and Maria L. No. "Cu-Al-Ni Shape Memory Alloy Composites with Very High Damping Capacity." In ICOMAT. John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118803592.ch32.

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Silva, Maria do Carmo, L. C. da Silva, and Francisco Ambrozio Filho. "High Energy Milling and Hot Extrusion of Equiatomic NiTi Shape Memory Alloy." In Advances in Science and Technology. Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/3-908158-16-8.18.

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Nakayama, Hiroyuki, and Minoru Taya. "Characteristics of Ti50-Pd(50-x)-W(x) High Temperature Shape Memory Alloy." In THERMEC 2006. Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.3190.

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Wellman, Parris S., William J. Peine, Gregg Favalora, and Robert D. Howe. "Mechanical design and control of a high-bandwidth shape memory alloy tactile display." In Experimental Robotics V. Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/bfb0112950.

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Meng, X. L., Yu Dong Fu, Wei Cai, J. X. Zhang, Qing Fen Li, and Lian Cheng Zhao. "Martensitic Transformation Behavior and Shape Memory Effect of an Aged Ni-rich Ti-Ni-Hf High Temperature Shape Memory Alloy." In Solid State Phenomena. Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/3-908451-49-3.399.

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Conference papers on the topic "High strength shape memory alloy"

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Buchanan, Edward R., and Regina B. Celin. "Fatigue Strength Enhancement Using Shape Memory Alloy Bushings." In ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/90-gt-316.

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In recent years, there have been a number of failures of aircraft engine and structural components which are believed to have resulted from the accumulation of fatigue damage. The treatment of such damage is therefore of great significance from the standpoints of increased reliability and extended usage. This paper presents the initial results of a program to evaluate a new process for the repair of fatigue-damaged aircraft engine components. In this process, the fatigue-damaged area is drilled out and replaced with a bushing manufactured from a new class of material called a ‘shape memory’ alloy. This material has the capability to expand in place following insertion, thus placing the surrounding material into compression. A significant improvement in low cycle fatigue life was observed at 288°C in Ti-6Al-4V specimens treated with the above technique. The degree of improvement is about twice that which was obtained with a mechanical cold expansion technique used commercially to extend fatigue life. The degree of improvement of the subject process is greater at high numbers of cycles than at low numbers of cycles. The subject project was funded as a Phase I Small Business Innovation Research award administered by the U.S. Naval Air Propulsion Center. Additional work in this area is planned which will a) identify the process parameters which will optimize the properties of shape memory alloy bushings, b) define the properties of shape memory alloy bushings over a wide range of temperature and loading conditions, and c) evaluate the effect in actual turbine engine hardware in a simulated engine environment.
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Xiao, Fu, Guojun Ma, Xinqing Zhao, Huibin Xu, Haichang Jiang, and Lijian Rong. "A novel TiNiNb shape memory alloy with high yield strength and high damping capacity." In International Conference on Smart Materials and Nanotechnology in Engineering. SPIE, 2007. http://dx.doi.org/10.1117/12.779884.

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Daghash, Sherif M., and Osman E. Ozbulut. "Superelastic Shape Memory Alloy Fiber-Reinforced Polymer Composites." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9174.

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Fiber reinforced polymer (FRP) composites have been increasingly used in engineering applications due to their lightweights, high strength, and high corrosion resistance. However, the conventional FRPs exhibits brittle failure, low toughness, limited fatigue strength, and relatively low ultimate tensile strains. Shape memory alloys (SMAs) are a class of metallic alloys that can recover large strains upon load removal with minimal residual deformations. Besides their ability to recover large deformations, SMAs possess excellent corrosion resistance, good energy dissipation capacity, and high fatigue properties. This study explores the use of superelastic SMA fibers to reinforce a thermoset polymer matrix to produce a polymer composite with enhanced mechanical properties. Nickel-Titanium wires with a diameter of 495 micrometer are used as fibers. SMA coupons with different reinforcement ratios are fabricated using a special-made mold and following a modified hand lay-up technique. The uniaxial tensile tests are conducted under cyclic loading protocols. The results of the tests are assessed in terms of ultimate strength, ultimate strain, residual strain, and failure modes of the composites.
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Ullakko, Kari, Peter G. Yakovenko, and Valentin G. Gavriljuk. "New developments in actuator materials as reflected in magnetically controlled shape memory alloys and high-strength shape memory steels." In 1996 Symposium on Smart Structures and Materials, edited by Vasundara V. Varadan and Jagdish Chandra. SPIE, 1996. http://dx.doi.org/10.1117/12.240825.

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Padisala, S. K., A. Bhardwaj, K. Poluri, and A. K. Gupta. "Effect of Constrained Groove Pressing on Mechanical Properties of Nitinol Alloy." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87295.

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Nitinol shape memory alloy is well known for its shape memory effect and super elastic effect. In the present work, the improvement of mechanical properties of nitinol alloy like yield strength, ultimate tensile strength and micro-hardness is discussed along with the study of evolution of micro-structure after every pass to extend the applications of shape memory alloys into high strength application areas. Severe plastic deformation processes are usually adopted for producing fine grain structures which improve the mechanical properties of a material. One such severe deformation process is constrained groove pressing, which is considered as one of the best severe plastic deformation techniques for sheet metals. The results of constrained groove pressing process on nitinol alloy show that the yield strength and the ultimate tensile strength have increased by about 3.6 times 2.5 times respectively, with an increment of 50% and 74% in micro-hardness after 1st pass of constrained groove pressing and 2nd pass of constrained groove pressing respectively. Microstructure shows increase in martensitic phase after constrained groove pressing processing. Increasing in twinning and grain boundary density can be observed in constrained groove pressing processed nitinol, which are the reasons for the tremendous increase in the strength of the alloy. Thus, the constrained groove pressing process on nitinol alloy can increase its range of application for high strength requirements.
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Tan, Honghao, and Mohammad H. Elahinia. "Modeling of Ferromagnetic Shape Memory Alloy Based Transducers for Electro-Hydraulic Actuators." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80049.

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Ferromagnetic Shape Memory Alloys (FSMAs) like Ni-Mn-Ga have attracted significant attention over the past few years. What makes these materials attractive as actuators is their high energy density, large stroke, and high bandwidth. Among other applications, these properties make FSMAs potentially candidates for developing lightweight Electro-Hydraulic Actuators (EHA). The role of the FSMA transducer is to provide the mechanical energy by the linear displacement in the EHA. In order to develop effective FSMA-based transducers, it is important to study their dynamic behavior. In this paper a dynamic model is presented for a Ni-Mn-Ga transducer. The transducer consists of the Ni-Mn-Ga material, a linear spring, Helmholtz coils, and a soft iron housing. An enhanced phenomenological model is also presented in this work to describe the strain output of the actuator in the response to the magnetic field strength. Using this model the effect of design parameters on the performance of the actuator is studied.
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Chiroiu, Veturia, Ligia Munteanu, and Calin Chiroiu. "On the Bending of a Cantilever Flexible Beam With an Embedded Ribbon of Shape Memory Alloy." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48363.

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The paper analyses the thermomechanical coupling between a cantilever aluminium beam and an embedded SMA ribbon. The SMA is selected to be Nickel-Titanium (NiTi) because of the high strength and large strains associated with this material. The actuation of the beam is achieved by applying a current across the SMA ribbon in order to heat the beam above the transition temperature. We show that the actuated beam exhibit the essential functions of an active system, i. e. the deflected beam may return to the initial configuration.
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Dabbaghi, Hediyeh, Mohammadreza Nematollahi, Keyvan Safaei Baghbaderani, Parisa Bayatimalayeri, and Mohammad Elahinia. "High-Temperature Oxidation Kinetics of Additively Manufactured NiTiHf." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8449.

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Abstract NiTi-based high-temperature shape memory alloys (HTSMAs) such as NiTiHf have been utilized in a broad range of applications due to their high strength and work output, as well as, their ability to increase the transformation temperatures (TTs). Recently, additive manufacturing techniques (AM) have been widely used to fabricate complex shape memory alloy components without any major modifications or tooling and has paved the way to tailor the manufacturing and fabrications of microstructure and critical properties of their final parts. NiTi alloys properties such as transformation temperatures can be significantly altered due to oxidation, which can occur during the manufacturing process or post-processing. In this work, the oxidation behavior of Ni-rich NiTi20Hf shape memory alloys, which was fabricated by the selective laser melting (SLM) method, is evaluated. Thermogravimetric analysis (TGA) is used to assess the kinetic behavior of the oxidation at different temperature ranges of 500, 700, and 900 °C for 20 hours in the air. After oxidation, to evaluate the microstructure and chemical composition X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) was conducted. The isothermal oxidation kinetics of conventional NiTi20Hf alloys were studied, and the results were compared to AM samples. Results show a two-stage oxidation rate at which oxidation increased with the high rate at the initial stage. As the oxidation time increased, the oxidation rate gradually decreased. The oxidation behavior of NiTiHf alloys initially obeyed logarithmic rate law and then followed by parabolic rate law. SEM results showed the formation of a multi-layered oxide scale, including TiO2, NiTiO3, and Hf oxide.
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Fu, Jin, Zhiheng Hu, Xu Song, and Mingwang Fu. "Effect of Hatch Angle Rotation on the Thermal and Mechanical Properties of Micro Selective Laser Melted NiTi Shape Memory Alloy." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8235.

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Abstract NiTi shape memory alloy (SMA) has been widely used for bio-medical and aerospace applications due to its unique properties, i.e. shape memory effect and pseudoelasticity. However, the high ductility and work-hardening effect of NiTi lead to poor machinability. Additive manufacturing (AM), with excellent capability of fabricating complicated structures, has been used to fabricate NiTi components. To meet the increasing demand of product miniaturization, micro selective laser melting (μSLM) system equipped with finer laser beam has been developed to improve manufacturing resolution. This work studies the fabrication of NiTi SMA parts by μSLM for the first time. The effect of hatch angle rotation on the thermal and mechanical behaviors of μSLMed NiTi is analyzed. Columnar grains accompanied with equiaxed grains are observed in μSLMed NiTi. Laser rotation angles of 45/60/90° lead to weak crystallographic texture. Ti-rich secondary phases including Ti2Ni/Ti4Ni2Ox and TiC1-xNx are detected in the raw NiTi powder and the as-printed NiTi parts, respectively. The as-printed parts under different hatch angles show similar phase constitution. The thermal-induced transformation behavior was depressed with absence of transformation peak. The variation of hatch angle cannot activate the transformation peak. Varying hatch angle from 45° to 90°, the compressive strength and ductility reduce, and the hardness increases. The depressed thermal-/stress-induced phase transformation of the μSLM NiTi can be attributed to the Ti-rich secondary phases, which cause variation of matrix Ni/Ti ratio and inhomogeneous microstructure.
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Spinella, Igor, Eugenio Dragoni, and Francesco Stortiero. "Modelling, Prototype Construction and Testing of Helical Shape Memory Springs With Hollow Cross-Section." In ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1230.

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Shape memory alloys (SMAs) are used in many applications as actuators. The main drawbacks that limit the use of the SMAs in the field of micro-actuation are the low bandwidth and the unsatisfactory stroke. This paper contributes to enhancing the performances of SMA actuators by proposing a new SMA helical spring with hollow section. The hollow spring is modelled, then it is constructed and finally it is tested, comparing its performances with those of a spring with solid cross-section of equal stiffness and strength. Emptied of the inefficient material from its centre, the hollow spring features a lower mass (37% less) and an extremely lower cooling time (four times less). These results demonstrate that helical springs with hollow construction can be successfully exploited to realize SMA actuators with high bandwidth and stroke.
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