Journal articles: 'Mechanical engineering. Shape memory alloys. High pressure (Technology)'

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Gurau, Gheorghe, Carmela Gurau, Mihaela Banu, and Leandru Gheorghe Bujoreanu. "Microstructural Evolution in Ultrafine Grained FeMnSiCr Shape Memory Alloy Modules." Advanced Materials Research 1143 (February 2017): 214–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1143.214.

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High speed high pressure torsion (HSHPT) processing technology, engineered to achieving (ultra) fine bulk metallic structure under high pressure (~ GPa) and torsion by applying supplementary elevated rotation speed of superior anvil. Coned-disk spring shape modules were processed from an as cast Fe-28Mn-6Si-5Cr (mass %) shape memory alloy (SMA). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed that the structure of modules became submicron as an effect of HSHPT processing. After severe plastic deformation, a grain size gradient was obtained along the truncated cone generator, increasing from inner to outer areas, due to different deformation degrees in these zones. The mechanical and shape memory properties was performed in order to relate the structural changes caused by severe plastic deformation.

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Aleksei, Grunin, Maksimova Ksenia, and Goikhman Aleksander. "The features of Ni2MnIn polycrystalline Heusler alloy thin films formation by pulsed laser deposition." Open Engineering 11, no. 1 (December 20, 2020): 227–32. http://dx.doi.org/10.1515/eng-2021-0019.

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AbstractThe Ni-Mn-In-based Heusler alloys belong to the most studied intermetallic compounds due to a variety of physical effects inherent to them, including the shape memory and magnetocaloric effect, field-induced structural phase transition, and others. All of these properties are strongly depend on element concentrations, uniformity, and purity of the structure. Therefore, rather strict requirements are imposed on the synthesis technology of such samples.We report the dependencies of Ni-Mn-In polycrystalline thin film composition on growth parameters. It was shown that the composition mismatch between sample and target caused by the resputtering of the sample material with high-energy particles of the ablation plume, and the different ablation yields of elements from the target. The main deposition parameters demonstrated (Ar growth pressure, laser energies, substrate temperature and annealing, target-to-sample distance) for the co-deposition process to obtain the Ni-Mn-In Heusler alloy polycrystalline thin films with the martensitic transition.

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Shuitcev, A., D. V. Gunderov, B. Sun, L. Li, R. Z. Valiev, and Y. X. Tong. "Nanostructured Ti29.7Ni50.3Hf20 high temperature shape memory alloy processed by high-pressure torsion." Journal of Materials Science & Technology 52 (September 2020): 218–25. http://dx.doi.org/10.1016/j.jmst.2020.01.065.

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Gunderov, Dmitriy, Alexandr Lukyanov, Egor Prokofiev, Anna Churakova, Vladimir Pushin, Sergey Prokoshkin, Vladimir Stolyarov, and Ruslan Valiev. "Microstructure and Mechanical Properties of the SPD-Processed TiNi Alloys." Materials Science Forum 738-739 (January 2013): 486–90. http://dx.doi.org/10.4028/www.scientific.net/msf.738-739.486.

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The article represents results of influence of different severe plastic deformation (SPD) techniques on TiNi alloys. It is demonstrated that strength and shape memory effect (SME) of TiNi can be significantly enhanced due to formation of ultrafine-grained (UFG) and nanocrystalline (NC) structures by SPD. Influence of equal channel angular pressing (ECAP), high pressure torsion (HPT), multi-step SPD deformations (ECAP plus cold rolling) on structure, mechanical and functional properties of TiNi alloys is considered. There are represented first results of influence of equal channel angular pressure-Conform (ECAP-C) on TiNi alloys, which is a perspective technology for industrial fabrication of UFG metals and alloys.

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Gerstein, Gregory, Victor A. L'vov, Anna Kosogor, and Hans J. Maier. "Internal pressure as a key thermodynamic factor to obtain high-temperature superelasticity of shape memory alloys." Materials Letters 210 (January 2018): 252–54. http://dx.doi.org/10.1016/j.matlet.2017.09.034.

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Salowitz, Nathan, Ameralys Correa, Trishika Santebennur, Afsaneh Dorri Moghadam, Xiaojun Yan, and Pradeep Rohatgi. "Mechanics of nickel–titanium shape memory alloys undergoing partially constrained recovery for self-healing materials." Journal of Intelligent Material Systems and Structures 29, no. 15 (June 18, 2018): 3025–36. http://dx.doi.org/10.1177/1045389x18781260.

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Engineered self-healing materials seek to create an innate ability for materials to restore mechanical strength after incurring damage, much like biological organisms. This technology will enable the design of structures that can withstand their everyday use without damage but also recover from damage due to an overload incident. One of the primary mechanisms for self-healing is the incorporation of shape memory fibers in a composite type structure. Upon activation, these shape memory fibers can restore geometric changes caused by damage and close fractures. To date, shape memory–based self-healing, without bonding agents, has been limited to geometric restoration without creating a capability to withstand externally applied tensile loads due to the way the shape memory material has been integrated into the composite. Some form of bonding has been necessary for self-healing materials to resist an externally applied load after healing. This article presents results of new study into using a form of constrained recovery of nickel–titanium shape memory alloys in self-healing materials to create residual compressive loads across fractures in the low temperature martensitic state. Analysis is presented relating internal loads in self-healing materials, potentially generated by shape memory alloys, to the capability to resist externally applied loads. Supporting properties were experimentally characterized in nickel–titanium shape memory alloy wires. Finally, self-healing samples were synthesized and tested demonstrating the ability to resist externally applies loads without bonding. This study provides a new useful characterization of nickel–titanium applicable to self-healing structures and opens the door to new forms of healing like incorporation of pressure-based bonding.

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Wheeler, Robert W., Othmane Benafan, Frederick T. Calkins, Xiujie Gao, Zahra Ghanbari, Garrison Hommer, Dimitris Lagoudas, et al. "Engineering design tools for shape memory alloy actuators: CASMART collaborative best practices and case studies." Journal of Intelligent Material Systems and Structures 30, no. 18-19 (September 22, 2019): 2808–30. http://dx.doi.org/10.1177/1045389x19873390.

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One of the primary goals of the Consortium for the Advancement of Shape Memory Alloy Research and Technology is to enable the design of revolutionary applications based on shape memory alloy technology. To advance this goal and reduce the development time and required experience for the fabrication of shape memory alloy actuation systems, several modeling tools were developed for common actuator types and are discussed along with case studies, which highlight their capabilities and limitations. Shape memory alloys have many potential applications as reliable, lightweight, solid-state actuators given their ability to sustain high stresses and recover large deformations. In this article, modeling frameworks are developed for three common actuator designs: wires, lightweight, low-profile, and easily implemented; coiled springs, offering actuation strokes upward of 200% at reduced mechanical loads; and torque tubes, which can provide large actuation torques in small volumes and repeatable low-load actuation. Although the design and integration of a shape memory alloy–based actuation system requires application- and environment-specific engineering considerations, common modeling tools can significantly reduce the investment required for actuation system development and provide valuable engineering insight. This analysis presents a collection of Consortium for the Advancement of Shape Memory Alloy Research and Technology collaborative best practices to allow readers to utilize the available design tools and understand their modeling principles.

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Simone, Filomena, Gianluca Rizzello, and Stefan Seelecke. "A finite element framework for a shape memory alloy actuated finger." Journal of Intelligent Material Systems and Structures 30, no. 14 (July 5, 2019): 2052–64. http://dx.doi.org/10.1177/1045389x19861787.

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This article presents on finite element modeling of an artificial finger driven by shape memory alloy wires. These alloys appear as a promising transduction technology, due to their inherently high energy density which makes them a good choice for compact, lightweight, and silent actuator systems with many applications in the robotic field, ranging from industrial to biomedical ones. However, the complex nonlinear and hysteretic behavior of the material makes it difficult to accurately model and design shape memory alloy–actuated systems. The problem is even more challenging when shape memory alloys are used as actuators in articulated structures, adding complex kinematics and contact situations to the picture. In this article, a finite element model is developed to describe the behavior of a finger prototype, in which a bundle of shape memory alloy wires works against an extension spring. The commercially available software COMSOL is used for implementing the coupling and contact issues between the finger structure and the shape memory alloy wires. To describe the shape memory alloy material behavior, a COMSOL implementation of the Müller–Achenbach–Seelecke model is presented. By means of different experiments, it is demonstrated how the model predicts the prototype behavior in relation to different power stimuli and actuator geometries.

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Achiţei, Dragoş Cristian, Petrică Vizureanu, Alina Adriana Minea, Mohd Mustafa Al Bakri Abdullah, Mirabela Georgiana Minciună, and Andrei Victor Sandu. "Improvement of Properties of Aluminum Bronze CuAl₇Mn₃ by Heat Treatments." Applied Mechanics and Materials 657 (October 2014): 412–16. http://dx.doi.org/10.4028/www.scientific.net/amm.657.412.

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Top domains of technology, such as aerospace, nuclear technology, electrical engineering, electronics, energy, require materials and alloys with special properties: superconductivity, superplasticity, high resistance to corrosion, shape memory, exceptional mechanical strength, magnetism, and resistivity. Aluminum bronzes are bronze with very good mechanical and chemical properties, which are factory profiles, strips, bearings, gears, valves, parts and fittings for chemical and food industry, gears, water pump housings, mainly parts corrosion resistant in aggressive environments.

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Schmelter, Tobias, Benedict Theren, Sebastian Fuchs, and Bernd Kuhlenkötter. "Development of an Actuator for Translatory Movement by Means of a Detented Switching Shaft Based on a Shape Memory Alloy Wire for Repeatable Mechanical Positioning." Crystals 11, no. 2 (February 6, 2021): 163. http://dx.doi.org/10.3390/cryst11020163.

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Actuators based on the shape memory effect have recently become more and more economically important due to the many advantages of shape memory alloys (SMAs), such as their high energy density. SMAs are usually used to control the end/maximum positions, thus the actuators always move between two positions. The repeatable control of intermediate positions has so far proven difficult, because in most cases, external sensors are necessary to determine the length of the SMA element. Additionally control strategies for SMA actuators are rather complex due to the non-linear behavior of this material. The SMA actuator presented here is able to control intermediate positions with repeatable accuracy without the need of a separate control technology. The integrated control unit is based on a mechanical principle using a shaft with a circumference groove. This groove has a height profile that turns the shafts rotation, generated by the SMA, into a translational movement. Therefore, the SMA wire generates a partial stroke at each complete activation, turning the shaft partially. With several activation cycles in a row, the stroke adds up until reaching the maximum. A further activation cycle of the wire resets the actuators stroke to its initial position. Each part of the stroke can, thereby, be controlled precisely and repeatedly within the scope of each complete cycle of the actuator. Based on an integrated ratchet, each stroke of the actuator can hold energy free.

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Fang, X., G. Shao, and Z. Fan. "Microstructure and Mechanical Properties of Fe-Containing Al-Alloys Processed by a Rheo-Diecasting Process." Materials Science Forum 519-521 (July 2006): 1251–56. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.1251.

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Al-Fe compounds are usually present in the as-cast microstructure of Al-alloys as large needles or plates. As such, they have a detrimental effect on the mechanical properties of Al-alloys containing Fe, either as an impurity element or as an alloying addition. However, Fe-containing Al-alloys also offer attractive physical properties, such as improved stiffness, wear resistance and thermal resistance. If the needle and plate morphology of the Al-Fe compounds can be modified to a more compact morphology, with refined particle size and uniform distribution, the mechanical properties of Al-Fe based Al-alloys can be substantially improved, and therefore, they will find wider applications in many engineering sectors. A new semisolid metal processing technology, rheodiecasting (RDC), has been developed for production of Al-alloy components with high integrity. The RDC process innovatively combines the dispersive mixing power of the twin-screw mechanism, for the creation of high quality semisolid slurry, with the high efficiency, low cost nature of the high-pressure diecasting (HPDC) process for component shaping. In this paper, we present our experimental results on the effects of intensive melt shearing on the size and morphology of Al-Fe compounds in A380 alloys, with different levels of Fe additions. The experimental results have shown that intensive melt shearing during solidification can effectively change the particle shape from the usual needles and plates, to an equiaxed morphology. Samples which have undergone with melt shearing, exhibit much improved strength and ductility compared to those with the same level of Fe addition, but without exposure to melt shearing.

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Jung, Hwa Chul, Ye Sik Kim, and Kwang Seon Shin. "Manufacturing and Application of Continuous Cast Semi-Solid Processed Magnesium Alloys." Materials Science Forum 488-489 (July 2005): 397–400. http://dx.doi.org/10.4028/www.scientific.net/msf.488-489.397.

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The demand for magnesium alloys has increased significantly during the past decade in the automotive and electronic industries where weight reduction becomes increasingly an important issue. At present, high-pressure die casting (HPDC) is a dominant process in production of magnesium alloy components. However, magnesium alloy components produced by HPDC suffer from porosity problem and this limits the enhancement of mechanical properties through subsequent heat treatments. The semi-solid processing (SSP) is an emerging new technology for near-net shape production of engineering components, in which the alloys are processed in the temperature range where the liquid and solid phases coexist. The SSP has various advantages over the conventional casting processes. It offers the castings with high integrity and less porosity and allows subsequent heat treatments for enhancement of mechanical properties. For these advantages, the SSP of magnesium alloys has received increasing attention in recent years. In the present study, the continuous casting process was developed for the production of magnesium billets for the subsequent SSP. The process utilizes an electromagnetic stirring system in order to obtain desired microstructure with an excellent degree of homogeneity in both microstructure and composition. Prototypes of an air conditioner cover and a telescope housing were produced using the SSP of the continuously cast magnesium alloy billets.

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Beyer, Jeno, and Jan H. Mulder. "Recent Developments in High Temperature Shape Memory Alloys." MRS Proceedings 360 (1994). http://dx.doi.org/10.1557/proc-360-443.

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AbstractThe functional properties of Shape Memory Alloys (SMA's) are used succesfully at present in a variety of industrial and medical applications. The use of these materials in smart structures is now emerging in the field of aeronautic/space technology. Many applications require higher operating temperatures than available to date, or higher cooling rates and/or a higher number of cycles. For this purpose the properties and fabricability of commercial alloys as Ni-Ti-(X), Cu-Al-Ni or Cu-Zn-Al are being adjusted and improved. Other feasible alloys are being developed. The research and development is directed towards the control of the stress, strain, temperature and time dependence of shape memory properties for a stable in-service behaviour. In this paper the various approaches taken up in recent years by academic and industrial laboratories for developing high temperature SMA's are reviewed.

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Baldwin, Elizabeth, and Afsaneh Rabiei. "High Transition Temperature Shape Memory Alloys for Micro-actuator Systems." MRS Proceedings 785 (2003). http://dx.doi.org/10.1557/proc-785-d7.9.

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ABSTRACTA new generation of thin film shape memory alloy (SMA) for MEMS micro-actuator has been developed, in which film structure and chemistry are optimized, for enhanced higher transition temperature, higher strain recovery rate as well as reduced actuation time by improving the heat transfer rates. Thin film TiPdNi was produced using Ion Beam Assisted Deposition (IBAD) technique both by in-situ heat treating during deposition and followed by post processing heat treatment. Films deposited on unheated substrates were found to be highly amorphous with minimal B2 austenite crystallization, while films deposited on heated substrates produced a highly crystallized twinned B19 martensitic structure through the bulk of the film. For films deposited on heated substrates, a 70 nm thick transition layer was found to exist between the bulk film and silicon substrate. Severe delamination and oxidation as a result of post heat treatment on IBAD deposited samples made in-situ heat treatment most suitable for processing thin film SMAs for MEMS applications. The desire to introduce this innovative technology to the field of SMA micro-actuators is based on two primary advantages of IBAD process over existing technology used to apply thin film SMAs. First, the chemical composition and grain size of the applied coating can be precisely controlled over a wide range of values. Second, the SMA can be deposited as thin films ≤ 2 μm thick with smaller grain size, much denser than films applied using sputter deposition technology. The effects of various processing parameters, and post processing heat treatment, on properties of the thin film SMA were studied.

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Lohse, Felix, Carmen Wende, Klaus-Dieter Klass, Rico Hickmann, Eric Häntzsche, Quentin Bollengier, Moniruddoza Ashir, et al. "Bio-inspired semi-flexible joint based on fibre-reinforced composites with shape memory alloys." Journal of Intelligent Material Systems and Structures, September 22, 2020, 1045389X2095946. http://dx.doi.org/10.1177/1045389x20959460.

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Shape memory alloys (SMA) are a promising material class for active lightweight structure applications with movement functionality. Due to their high activation energy potential and good processability in wire shape, they are well suited for application in actively deformable, fibre-reinforced composite structures. In order to generate large deflections from the limited deformation potential of SMA, detailed analysis of the deformation mechanisms is required. In this work, a bionic approach is pursued, investigating the characteristics of locomotion systems of insects. A simplified joint concept is derived from the cockroach knee and implemented using flat knitting technology. A composite joint is manufactured with a resin infusion process and experimentally verified in regards to its motion behaviour. The presented results show good deformation behaviour with large deformation angles up to 60°, suggesting large potential for further development of the presented approach.

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Söderberg, Outi, Ilkka Aaltio, Yanling Ge, Alexandr Soroka, Raisa Niemi, Xuwen Liu, and Simo-Pekka Hannula. "Recent Development of the Magnetic Shape Memory Materials Research in Finland." MRS Proceedings 1200 (2009). http://dx.doi.org/10.1557/proc-1200-g03-03.

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AbstractNi-Mn-Ga based magnetic shape memory (MSM) materials have been studied since 1998 in Finland at the Helsinki University of Technology (TKK, previously HUT). The large HUT-MSM-project resulted in MSM-alloys with high service temperature, 10 % field-induced-strain, as well as circumstances when and how a Ni-Mn-Ga alloy exhibits this phenomenon. The understanding of the structure and behavior of twin boundaries, and their role, for example, in the vibration damping and long-term actuation has been enhanced in the recent projects. Twin boundaries have been studied by XRD, by high-resolution transmission electron microscopy (HRTEM), and by in-situ straining in TEM, the last one in co-operation with the Institute of Physics in Prague (ASCR-IP), Czech Republic. The results obtained by neutron diffraction in co-operation with Hahn-Meitner-Institut Berlin, Institute for Metal Physics (IMP), Kiev, and Institut Laue-Langevin (ILL), Grenoble, have given new crystallographic information. Damping of Ni-Mn-Ga polymer composites has been proved to be excellent at high stiffness levels with the loss factor = 0.6 at E ≈ 1 GPa. This research was carried out in co-operation with the University of California Los Angeles (UCLA), USA. In the long-term actuation, a fatigue life of 2×109 has been recorded for a five-layered modulated Ni-Mn-Ga structure in mechanical cycling. The evolution of the MSM parameters during the long-term use is recorded and used as an input data for the models developed in the European MAFESMA co-operation. The search for alloys with wide stable thermal property range showing MSM effect has continued and alloys that are stable down to 4 K have been established. Modeling based on Ginsburg-Landau theory has been applied to evaluate aging and thermal fluctuations in the modulated Ni-Mn-Ga structures. As a commercial target, AdaptaMat Ltd. develops technology to produce Ni-Mn-Ga magnetic shape memory material with improved quality, lower twinning stress, longer fatigue life as well as lower cost and better availability for use in research and development.

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Kyogoku, Hideki, Takeshi Kadomura, Shinichiro Komatsu, Fusahito Yoshida, and Toshio Sakuma. "Thermo-Mechanical Characteristics of Ti-Ni-Cu Shape Memory Alloy Fabricated by Pulse-Current Pressure Sintering Method." MRS Proceedings 785 (2003). http://dx.doi.org/10.1557/proc-785-d7.6.

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ABSTRACTThe Ti-Ni-Cu shape memory alloy by elemental powders was fabricated by means of a pulse-current pressure sintering method that can produce high-density sintered compacts in a very short sintering time. The fabrication conditions of Ti-Ni-Cu alloy and the influence of Cu content in Ti-Ni-Cu alloy on the tensile properties and thermo-mechanical characteristics were investigated. The relative density of the as-sintered compacts was around 97% at any Cu content. The microstructure, tensile properties and thermo-mechanical characteristics of the as-sintered compacts were improved greatly by performing a solid solution heat-treatment. The yielding behavior due to the stress-induced martensite in stress-strain curves of the alloy took place after elastic deformation at any Cu content. The deformation resistance of the alloys changed with Cu content, and it was lowest around 9at% in Cu content. The tensile strength and elongation of the alloy with Cu content around 9at% were more than 400 MPa and 6%, respectively. It was found that the thermo-mechanical behavior of the alloy becomes stable by performing cyclic deformation.

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Thienhaus, Sigurd, Christiane Zamponi, Holger Rumpf, Jae Hattrick-Simpers, Ichiro Takeuchi, and Alfred Ludwig. "High-throughput characterization of shape memory thin films using automated temperature-dependent resistance measurements." MRS Proceedings 894 (2005). http://dx.doi.org/10.1557/proc-0894-ll06-06.

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AbstractShape memory alloy (SMA) thin films are used as actuator materials in MEMS due to their unique properties. Binary thin films with a composition close to Ni50Ti50 are well-established materials, whereas ternaries like NiTiCu, NiTiPd, NiTiHf are less studied. Furthermore, new alloys are being developed which show a magnetic shape memory effect, e.g. Ni2MnGa. For the optimization of known, and the development of new, SMA thin films, a fast and reliable characterization technology is needed, which rapidly identifies the transformation temperatures (i.e. martensite and austenite start and finish temperatures) for a range of material compositions deposited on a whole wafer. In this paper, automated temperature-dependent resistance measurements are discussed as a means which yields the thermal hysteresis of the investigated thin films. Results of monitoring the uniformity of shape memory film depositions on the wafer level, as well as results on the use of this method as a tool for screening for new SMA films by characterization of materials libraries are reported.

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Journal articles on the topic 'Mechanical engineering. Shape memory alloys. High pressure (Technology)'

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