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1
Yang, Kaike, Junpeng Luo, Zhaoting Yuan, et al. "Topology Optimization of Shape Memory Alloy Actuators for Prescribed Two-Way Transforming Shapes." Actuators 13, no. 2 (2024): 65. http://dx.doi.org/10.3390/act13020065.
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This paper proposes a new topology optimization formulation for obtaining shape memory alloy actuators which are designed with prescribed two-way transforming shapes. The actuation behaviors of shape memory alloy structures are governed by austenite-martensite phase transformations effected by thermal-mechanical loading processes; therefore, to realize the precise geometric shape variations of shape memory alloy actuators, traditional methods involve iteration processes including heuristic structural design, numerical predictions and experimental validation. Although advanced structural optimization methods such as topology optimization have been used to design three-dimensional (3D) shape memory alloy actuators, the maximization/minimization of quantities such as structural compliance or inaccurate stroke distances has usually been selected as the optimization objective to obtain feasible solutions. To bridge the gap between precise shape-morphing requirements and efficient shape memory alloy actuator designs, this paper formulates optimization criteria with quantitatively desired geometric shapes, and investigates the automatic designs of two-way prescribed shape morphing shape memory alloy structures based on the proposed topology optimization method. The super element method and adjoint method are used to derive the analytical sensitivities of the objective functions with respect to the design variables. Numerical examples demonstrate that the proposed method can obtain 3D actuator designs that have the desired two-way transforming shapes.
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Kubášová, Kristýna, Veronika Drátovská, Monika Losertová, et al. "A Review on Additive Manufacturing Methods for NiTi Shape Memory Alloy Production." Materials 17, no. 6 (2024): 1248. http://dx.doi.org/10.3390/ma17061248.
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The NiTi alloy, known as Nitinol, represents one of the most investigated smart alloys, exhibiting a shape memory effect and superelasticity. These, among many other remarkable attributes, enable its utilization in various applications, encompassing the automotive industry, aviation, space exploration, and, notably, medicine. Conventionally, Nitinol is predominantly produced in the form of wire or thin sheets that allow producing many required components. However, the manufacturing of complex shapes poses challenges due to the tenacity of the NiTi alloy, and different processing routes at elevated temperatures have to be applied. Overcoming this obstacle may be facilitated by additive manufacturing methods. This article provides an overview of the employment of additive manufacturing methods, allowing the preparation of the required shapes of Nitinol products while retaining their exceptional properties and potential applications.
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Liu, Bingfei, and Yaxuan Pan. "Effect of Pore Shape on Mechanical Properties of Porous Shape Memory Alloy." Micromachines 13, no. 4 (2022): 566. http://dx.doi.org/10.3390/mi13040566.
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Porous shape memory alloys (SMAs) have been widely used in the aerospace, military, medical, and health fields due to its unique mechanical properties such as superelasticity, biocompatibility, and shape memory effect. In this work, the pore shape was considered in the constitutive model of the porous SMAs by respectively introducing the parameter of aspect ratio and for different pore shapes including oblate, sphere, and prolate shapes, so the expression of Young’s modulus for the porous SMA can be derived. Then, the constitutive model for such a porous shape memory alloy was established. When the porosity was zero, the model can be degenerated to the dense case. The stress–strain curves for the porous SMA with a porosity of 13% with different aspect ratio are then given. Numerical results showed good agreement with the published experimental data that proved the validation of the model. Based on the proven constitutive model, the properties of porous SMA with different porosity and pore shapes are discussed. The results showed that the pore shapes and the porosities had a big effect on the stress–strain curves for the porous shape memory, while with the increasing porosities, the Young’s modulus and the hysteresis both decreased. With the same porosities, the Young’s modulus and hysteresis loop of SMA with round pores were the largest, while the Young’s modulus and hysteresis loop were the smallest when r=0.1, and they were greater when r=0.75 than when r=10. It can be seen that the closer to the circle, the better the performance of the material.
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de Brito Simões, Jackson, Francisco Fernando Roberto Pereira, Jorge Otubo, and Carlos José de Araújo. "Influence of Heat Treatments on a NiTi Shape Memory Alloy Obtained Using Vacuum Induction Melting and Reprocessed by Plasma Skull Push-Pull." MRS Proceedings 1765 (2015): 121–26. http://dx.doi.org/10.1557/opl.2015.817.
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ABSTRACTShape memory alloys (SMA) are metallic attractive engineering materials due to their capacity to store pre-defined shapes through a thermally induced phase transition from a solid state. This paper aims to evaluate the influence of solubilization thermal treatments on a NiTi shape memory alloy originally fabricated by vacuum induction melting and then reprocessed by plasma melting followed by injection molding (Plasma Skull Push Pull process) into different metal molds (steel, aluminum, brass and copper) in order to compare the thermal properties regarding to its raw state. The thermal treatments of solubilization were carried out at 850°C in different times (2n function, n = 0, 1, 2 and 3, in hours). The influence of solubilizing treatments in the NiTi shape memory alloy was analyzed using the following characterization techniques: Differential Scanning Calorimetry (DSC) and Electrical Resistance as a function of Temperature (ERT). The results demonstrate that the solubilization heat treatments applied on the reprocessed NiTi shape memory alloy through the plasma skull push pull process, provides important changes in the phase transformation of the material. Therefore, it was demonstrated that it is necessary to solubilize the material after melting or remelting the NiTi shape memory alloy via this process to obtain mini-actuators products with homogeneous properties.
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Kitamura, Kazuhiro. "Shape Memory Properties of Ti-Ni Shape Memory Alloy / Shape Memory Polymer Composites Using Additive Manufacturing." Materials Science Forum 1016 (January 2021): 697–701. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.697.
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Shape memory alloys (SMAs) have the disadvantage that cooling is difficult and the actuating speed during cooling is slow. To resolve this problem, shape memory material actuators that operate only with heating is required. SMAs are characterized by a low apparent Young's modulus below the transformation temperature and a strong shape recovery force above the reverse transformation temperature. Alternatively, shape memory polymers (SMPs) have two properties: shape fixability and shape recovery. The SMPs are hardened below the glass transition (Tg) temperature and the material is recovered to memorized shape above the Tg temperature. The other hand, 3D printer is a machine that can directly output a 3D-designed product designed by a computer in 3D, and molded materials such as polymer, resin, metal, and ceramics. In this research, we developed the SMC of SMA wire and SMP sheet using adhesive that develops actuates into two shapes only by heating.
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Traleski, André Victor, Selauco Vurobi Jr., and Osvaldo Mitsuyuki Cintho. "Processing of Cu-Al-Ni and Cu-Zn-Al Alloys by Mechanical Alloying." Materials Science Forum 727-728 (August 2012): 200–205. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.200.
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The mechanical alloying process provides alloys with extremely refined microstructure, reducing the need for alloying elements to grain growth restriction, as in casting techniques. The Cu-Al-Ni and Cu-Zn-Al alloys produced by casting may have the shape memory effect when plastically deformed at relatively low temperatures, returning to its original shape upon heating at a given temperature. This work aimed at the production of Cu-Al-Ni and Cu-Zn-Al alloys by mechanical alloying, followed by microstructural characterization and investigation of the shape memory effect by means of differential scanning calorimetry (DSC). Metal powders of Cu, Al, Ni and Cu, Zn, Al were processed in a SPEX high energy vibratory mill during 8 hours, with ball-to-powder weight ratio of 5:1. The milled products were characterized by X-ray diffraction. For each alloy, specimens with 8 mm diameter and 2 mm thickness were shapes by uniaxial pressing, sintered in a tube furnace with argon atmosphere, solubilized and then quenched in water. Samples were characterized by optical and scanning electron microscopy (SEM), Vickers hardness testing and DSC. An ultrafine microstructure was obtained in the Cu-Al-Ni alloy but the shape memory effect was not detected by DSC analysis because of second phase precipitation. The shape memory effect was not present in the Cu-Zn-Al alloy also, because of zinc oxidation during the sintering.
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Saravanos, Dimitris, Theodoros Machairas, Alex Solomou, and Anargyros Karakalas. "Shape Memory Alloy Morphing Airfoil Sections." Advances in Science and Technology 101 (October 2016): 112–20. http://dx.doi.org/10.4028/www.scientific.net/ast.101.112.
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Shape memory alloys (SMA) provide common solid state actuators with reliable and unique characteristics. Their special behavior is based on a reversible phase transformation and can provide high power density, induced strain and block force which render them indispensable for use in morphing structures that require large shape changes while space and weight restrictions are imposed. Yet, their implementation into morphing structures faces challenges related to their complex multi-disciplinary behavior, their interaction with the passive structural components, geometrical nonlinearity due to large shape changes, the lack of experimental data, and above all, the lack of modelling tools which can robustly simulate the complex thermomechanical behavior and make feasible their design. We briefly review the material characterization process, the developed modelling tools which can simulate the complex thermomechanical response of morphing structures with SMA actuators which can undergo large shape changes under severe geometric nonlinearity, and the testing of prototype morphing components. The design and validation of two morphing structural concepts for curvature control are presented. A morphing strip capable to deform towards a single target shape is initially presented. Subsequently, a morphing airfoil concept implementing an articulated mechanism capable to achieve multiple target shapes for aerodynamic load control is presented. The challenging task to continuously adapt the structural shape to time varying demands, dictates the use of antagonistic actuator configurations to maximize and control the range of morphing. The previously mentioned morphing airfoil configuration is used to alleviate the aerodynamic fatigue loads in wind turbine blades and aircraft wings.
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Spaggiari, Andrea, and Eugenio Dragoni. "Analytical modelling of Rolamite mechanism made of shape-memory alloy for constant force actuators." Journal of Intelligent Material Systems and Structures 28, no. 16 (2016): 2208–21. http://dx.doi.org/10.1177/1045389x16667560.
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This article analyses the Rolamite architecture exploiting shape-memory alloys as power element to obtain a solid-state actuator. The Rolamite mechanism was discovered in the late 1960s, initially as precision and low friction linear bearing. The most common Rolamite configuration consists of a flexible thin metal strip and two rollers mounted between two fixed parallel guide surfaces. The system can roll back and forth without slipping guided by the plates along its so-called sensing axis. The system presents another relevant advantage in addition to low friction coefficient, which is the possibility to provide force generation in a quite simple way. In the original literature works, the force was provided, thanks to cut-outs of various shapes in the strip, although this method does not allow the Rolamite to be considered a proper actuator, but only a force generator. In this article, we developed the idea of exploiting the shape-memory alloy as Rolamite power element, and therefore, to use the shape-memory effect to change the elastic properties of the strip and to provide the actuation force. The mechanical analysis, where the martensite–austenite transition is modelled in a simplified way, shows that this application is feasible, mainly thanks to the initial precurvature of the shape-memory alloy strip. The discussion of the results highlights some important merits of this architecture such as long stroke, constant force and compactness.
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Adiguzel, Osman. "Phase Transitions and Elementary Processes in Shape Memory Alloys." Advanced Materials Research 1101 (April 2015): 124–28. http://dx.doi.org/10.4028/www.scientific.net/amr.1101.124.
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Shape memory effect is a peculiar property exhibited by certain alloy systems, and shape memory alloys are recognized to be smart materials. These alloys have important ability to recover the original shape of material after deformation, and they are used as shape memory elements in devices due to this property. The shape memory effect is facilitated by a displacive transformation known as martensitic transformation. Shape memory effect refers to the shape recovery of materials resulting from martensite to austenite transformation when heated above reverse transformation temperature after deforming in the martensitic phase. These alloys also cycle between two certain shapes with changing temperature.Martensitic transformations occur with cooperative movement of atoms by means of lattice invariant shears on a {110} - type plane of austenite matrix which is basal plane of martensite.Copper based alloys exhibit this property in metastable β-phase field. High temperature β-phase bcc-structures martensiticaly undergo the non-conventional structures following two ordered reactions on cooling, and structural changes in nanoscale level govern this transition cooling. Atomic movements are also confined to interatomic lengths due to the diffusionless character of martensitic transformation.
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CIURCĂ, Lenuța, Bogdan PRICOP, Mihai POPA, Victor Daniel APOSTOL, and Leandru-Gheorghe BUJOREANU. "On the Free Recovery Bending Shape Memory Effect in Powder Metallurgy FeMnSiCrNi." Annals of “Dunarea de Jos” University of Galati. Fascicle IX, Metallurgy and Materials Science 44, no. 3 (2021): 5–11. http://dx.doi.org/10.35219/mms.2021.3.01.
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This paper presents the results of an original experimental study on the training capacity of a powder metallurgy (PM) FeMnSiCrNi shape memory alloy (SMA). The specimens were sintered under protective atmosphere from blended elemental powders, 50 vol.%. of alloy particles being mechanically alloyed. Lamellar specimens, hot rolled to 1 mm thickness, were bent against cylindrical calibres with five decreasing radii, to induce cold shapes with higher and higher deformation degree, as compared to the straight hot shape. During the training procedure, bent specimens were heated with a hot air gun, and developed free-recovery shape memory effect (SME) and partially deflected, by reducing their curvature. The first set of experiments involved fastening the specimens at one end, heating it and monitoring free end’s displacement by means of cinematographic analysis. Within the second set of experiments, both cold and hot shapes were recorded and digitalized and their chord’s length (b) and circle segment height (a) were measured and the radius was determined as R = a/2 + b2/8a for the cold (Rc) and hot shapes (Rh). Finally, the shape recovery degree was calculated for the nth calibre as Δrecn = (Rhn-Rrn)/(Rhn-1-Rrn) and the variation of Δrecn with calibre’s radius was discussed.
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Gopalakrishnan, T., M. Chandrasekaran, R. Saravanan, and P. Murugan. "An Ample Review on Compatibility and Competence of Shape Memory Alloys for Enhancing Composites." Advances in Materials Science and Engineering 2022 (October 3, 2022): 1–15. http://dx.doi.org/10.1155/2022/6988731.
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The name shape memory alloy (SMA) reveals its behavior of being an accurate heat-sensitive material in changing its shape based on the temperature. This ample review concentrates on the current scenario of including SMA in polymer matrix composites to achieve desired objectives. Polymer-based shape memory alloys are termed shape memory polymers (SMP), and they consist of deformable materials that are able to switch between their original shapes and temporary shapes, which can be generously designed. SMPs could be classified as smart materials by considering their low density, good biocompatibility, excessive deformation etc. On the other hand, many engineering applications of SMP uses have limitations and disadvantages. In this regard, the importance of SMPs has been analyzed based on the following aspects: synthesis method, fiber reinforcement, parameters that affected the polymer-based SMA, and implementation of multifunctionality materials. Fiber-reinforced polymer composites have more responsibilities for expanding interest in current innovative research and expected mechanical applications because of their significant space compared with conservative materials. A polymer composite presents effectively adaptable product properties, expected high strength-to-weight ratio, high flexibility in the manufacturing process, high corrosion resistance, and easy fabrication at a lower cost.
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Plăcintă, Constantin, Sergiu Stanciu, Mirela Panainte-Lehadus, et al. "Theoretical and Experimental Designs on Several Mechanical Properties of Cu–Al–Zn Shape Memory Alloys Used in the Processing Industry." Materials 16, no. 4 (2023): 1441. http://dx.doi.org/10.3390/ma16041441.
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By assimilating shape memory alloys with mathematical multifractal-type objects, a theoretical model based on Scale Relativity Theory in the form of The Multifractal Theory of Motion, in order to explain the mechanical behavior of such material, is proposed. The model is validated by analyzing the mechanical behavior of Cu–Al–Zn shape memory alloy with various chemical compositions. More precisely, the multifractal tunnel effect can “mime” the mechanical hysteresis of such a material, a situation in which a direct correspondence for several mechanical properties of Cu–Al–Zn is highlighted (the chemical composition can be correlated with the shapes of the curves controlled through the multifractality degree, while the areas delimited by the same curves can be correlated with the multifractal specific potential, as a measure of the mechanical memory degree).
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Kim, Taeyoon, Dohyung Kim, Wookjin Lee, and Wangryeol Kim. "Microstructure, Recovery Stress and Mechanical Property of Direct Energy Deposition Welded Fe-Mn-Si Based Shape Memory Alloy." Korean Journal of Metals and Materials 62, no. 12 (2024): 935–43. https://doi.org/10.3365/kjmm.2024.62.12.935.
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Direct Energy Deposition (DED) is one of the main methods of additive manufacturing in which a feedstock material in the form of powder or wire is delivered to a substrate while an energy source, such as laser beam or electron beam, is simultaneously applied to melt the feedstock. In addition to fabricating complex three-dimensional shapes using computer aided design, the DED laser welding process can be employed to fill complex shaped gaps between two objects. In this study, 3 mm thick Fe-based shape memory alloy plates with a 45° groove were welded by DED using high manganese steel powder filler. The process parameters including scan speed, hatch spacing, and layer thickness were fixed at values of 840 mm/min, 0.3 mm, 0.15 mm, respectively and laser power was varied during the welding process from 150 W to 300 W. Microstructures of the welds showed different shapes and quantities of defects such as cracks, pores and a lack of fusion depending on the laser power used. Laser power of 150 W showed crack-free weldment with the highest mechanical properties. The tensile strength and recovery stress of the welded sample were higher than the base metal, demonstrating the potential high performance of welding Fe-Mn-Si shape memory alloy components using the L-DED.
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Takashima, Kazuto, Hidetaka Suzuki, Toshiki Imazawa, and Hiroki Cho. "Motion Evaluation of Variable-Stiffness Link Based on Shape-Memory Alloy and Jamming Transition Phenomenon." Journal of Robotics and Mechatronics 36, no. 1 (2024): 181–89. http://dx.doi.org/10.20965/jrm.2024.p0181.
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In rapidly aging societies, the application of robots has spread from industry to nursing and social welfare. As the designs of industrial and non-industrial robots are different, numerous robot components with various shapes and stiffness are required for different tasks. In this study, we attached a variable-stiffness link based on a shape-memory alloy (SMA) and the jamming transition phenomenon to a robot arm and evaluated its pick-and-place motion for various objects with different shapes and weights. The link can be fixed in an arbitrary shape and then restored to its initial shape via the shape memory effect. The objects were picked up and moved by a prototype link, which consisted of four SMA wires inserted in the jamming mechanism. We compared two states of the link, namely with and without deformation of the link into a shape (the centerline and the cross section) to suit the target object using a mold. Experiments confirmed that changing and fixing the link shape to suit the target object increased both positioning accuracy and weight capacity.
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Takami, M., K. Fukui, S. Saitou, I. Sugiyama, and K. Terayama. "Application of a shape memory alloy to hand splinting." Prosthetics and Orthotics International 16, no. 1 (1992): 57–63. http://dx.doi.org/10.3109/03093649209164309.
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This paper describes new passive splints which have been developed using a shape memory alloy. The peculiar feature of the splints is that the way in which they change shape in use conforms to the stretching motion which it would be desirable to apply in certain conditions of deformity. The alloy consists of 55.66% by weight Nickel and 44.34% Titanium. The heat treatment of the alloy for memorising shape was implemented at 500°C for one hour. This alloy was easily bent when cool, but the original shape was recovered on heating. It was used as the supporting structure of the reverse knuckle bender splint and the cock-up splint. The new splints could be easily attached to the deformed limb after cooling. The splints avoided the development of spasticity, because they gradually recovered their original shapes and corrected the deformities when the heat of the room or body heat warmed the splints. Since the shape memory alloy has the dual function of thermal sensor and kinetic power source it was a simple device. The splint was, as a result, small and smart. It was apparent from clinical use that the splint was easy to wear and could be worn with comfort for an extended period. The design of the splints and the fabrication process are described and their application is indicated.
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Keshtta, Alaa, and Mohamed A. H. Gepreel. "Superelasticity Evaluation of the Biocompatible Ti-17Nb-6Ta Alloy." Journal of Healthcare Engineering 2019 (January 8, 2019): 1–8. http://dx.doi.org/10.1155/2019/8353409.
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Recently, studying the shape memory effect of the biocompatible Ti alloys takes much attention in the biomedical and healthcare applications. This study concerns about characterizing the superelasticity of the new biocompatible Ti-17Nb-6Ta (TNT) alloy. Microstructure of TNT was observed using optical and confocal microscopes. The alloy consists of two phases: β (predominant phase) and α″ martensite phase. The influence of cold rolling deformation on the microstructure was illustrated in which the martensitic-induced transformation appeared by cold rolling. The alloy is ductile as only the fracture dimples appeared in its fracture surface. Multicyclic loading and deloading tensile testing was applied to TNT specimens (flat and wire shapes) in order to evaluate the superelasticity. A superelastic strain as high as 3.5% was recorded for this TNT alloy. Therefore, TNT alloy has high potential for many biomedical and healthcare applications.
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Yoshida, Eiichi, Shigeru Kokaji, Satoshi Murata, Kohji Tomita, and Haruhisa Kurokawa. "Miniaturization of Self-Reconfigurable Robotic System using Shape Memory Alloy Actuators." Journal of Robotics and Mechatronics 12, no. 2 (2000): 96–102. http://dx.doi.org/10.20965/jrm.2000.p0096.
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This paper presents a small-size self-reconfigurable modular machine using shape memory alloy (SMA). The system is designed so that various shapes can be actively formed by a group of identical mechanical units. Each mechanical unit realizes two-dimensional rotational motion by using a novel actuator mechanism composed of two SMA torsion springs which can generate sufficient motion range and torque. The size and the weight of a unit are approximately 5[cm] cube and 80[g]. The reconfiguration motion of the machine is verified by many-unit experiments. Applicability of the developed unit model to a 3-D self-reconfigurable system is also discussed.
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Hsu, Chih Yu. "Shape Memory Alloy Combined with Piezoelectric Materials Applied for Structure Vibration Control." Advanced Materials Research 47-50 (June 2008): 29–32. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.29.
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A new configuration of smart structures which could be automatically adjusted according to changes of forcing frequencies is proposed for vibration suppression. The new configuration is a laminated beam-plate or wide beam composed of layers of piezoelectric sensors and actuators and Shape Memory Alloy (SMA) wires embedded in the middle plane of the laminated structure. The structural natural frequencies can be adjusted closely to the forcing frequencies by adjusting electric heating for controlling temperature of SMA. In each layer, the piezoelectric sensors and actuators whose electrode are trimmed to modal shapes in conjunction with proper control algorithm, to achieve expected control effects. The sensors and actuators are connected with each other if they have the same shapes and they are linked together by a controller to form a close loop feedback control. Using active control algorithm to control behavior of the piezoelectric material can suppress the structural vibration. Theoretical simulations are formulated and performed without physical experimentation for evaluating its feasibility. The Hamilton's principle is used to derive the governing equation and boundary conditions for the structure which is composed of PVDF and SMA materials. Modal analysis is used to obtain the result of dynamical response.
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Semba, Hiromasa, Nagatoshi Okabe, Toru Yamaji, Keisuke Okita, and Kiyoshi Yamauchi. "Axial Compressive Behavior of Single-Stage Bellows of TiNi Shape Memory Alloy for Seismic Applications." Materials Science Forum 475-479 (January 2005): 2055–58. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2055.
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The bellows formed of TiNi shape memory alloy (SMA) is proposed as a new type of seismic protection device. The bellows structure is known to have lower rigidity along the axial direction through effect of its shape. TiNi is known to be one of the most typical SMAs, which have high damping characteristics for dynamics engaged in its twin formation under martensite state and have the ability to recover completely from the large strain after unloaded and or heated. In this study, fundamental compressive behavior of TiNi bellows was investigated and discussed. Several shapes of TiNi single-stage bellows produced by rubber bulge method were prepared. They were heat-treated for some heat treatments and then examined on compression tests. Based on the results, the relationships among the bellows shapes and the stiffness, energy-absorbing capacity and so on were clarified. Finally, it was found from these results that single-stage bellows of TiNi SMA could be used as one of seismic protection devices.
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Kim, Chul, S. Hyun, and M. H. Cho. "Behaviors of Shape Memory Alloy Wire Embedded Smart Composite Skins and Actuators." Key Engineering Materials 261-263 (April 2004): 1463–68. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.1463.
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The shape changes by bending and twisting of a SMA/composite panel with embedded SMA wire actuators controlled by both electric resistive heating and passive elastic tailoring are investigated to realize the morphing wing of unmanned aerial vehicles. Three-dimensional finite element formulations are derived and used to analyze the behaviors of the SMA/composite smart structures. The numerical results show that the shapes of the SMA/composite panels can be controlled by judicious choices of control temperatures, SMA angles, and elastic tailoring. To validate the analytical results, two SMA-embedded curved panels are fabricated and then, their changes in shape are measured by a laser optical sensor when SMA is activated by electrically resistive heating. Both results show excellent correlation.
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Mahmood Baitab, Danish, Dayang Laila Abang Haji Abdul Majid, Ermira Junita Abdullah, and Mohd Faisal Abdul Hamid. "A review of techniques for embedding shape memory alloy (SMA) wires in smart woven composites." International Journal of Engineering & Technology 7, no. 4.13 (2018): 129. http://dx.doi.org/10.14419/ijet.v7i4.13.21344.
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Metallic structures, in various industrial fields such as transport and aerospace, are mostly replaced by composite structures having less weight and good strength. There is also a need of intensification of the operational dynamic environment with high durability requirements. So a smart composite structure is required that can manifest its functions according to environmental changes. One method of producing smart composite structures is to embed shape memory alloys in composite structures. Shape memory alloys (SMAs) have significant mechanical and thermodynamic properties and are available in very small diameters less than 0.2mm. These SMAs are embedded into composites for obtaining smart composites having tunable properties, active abilities, damping capacity and self-healing properties. Shape memory alloys are available in different shapes as wires, sheets, foils, strips, etc. For smart composites, mostly SMA embedded are in wire shape. Different techniques are used for embedding SMA wires in composites. SMA wires can be embedded between layers of laminates of composites, or embedded directly as reinforcement in matrix and can be woven into fabrics and used as a reinforcement. This paper reviews the different techniques of embedding SMA wires in composite structures, their pros and cons and their applications.
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Abdulkadhim, Hassan, Abdulkareem Hassan, and Ali Abdulaali. "2-D Actuator based Shape Memory Alloy using PID controller." Basrah journal for engineering science 22, no. 1 (2022): 1–8. http://dx.doi.org/10.33971/bjes.22.1.1.
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Over the past years, researchers have been focusing on development the robotics and actuation due to increase demand for these applications like industrial engineering, oil industry, healthcare, aerospace … etc. This work involves the design, construction and control of the Shape Memory Alloy (SMA) actuator. The industrial actuator has many characteristics able to be measured, which have an impact on the efficiency and effectiveness of the actuator while the execution of its tasks. The most important measurable characteristics are repeatability and accuracy. The current system typically is using Nitinol (Nickle Titanium Naval Ordinance Lab), which is one of the Shape Memory Alloy that contract when applying specific heat on it, and it can be used as an actuator. This work presents SMA in the shape of a spring to operate and control the accurate position of the 2-D system which containing four SMA springs, two SMA springs for the x-axis and two SMA springs for the y-axis. The theoretical design and calculations for SMA springs have been presented to collect information about the SMA springs. In a practical manner, the SMA spring characteristic like force and displacement were collected by a test bed that was designed and constructs before making the final rig. The setting shape of the SMA spring was presented and done as per the theoretical calculations. In the rig, each axis works as a two-direction actuator, the actuator is not prone to precise position points due to hysteresis and temperature variation. The SMA spring exhibited hysteresis and imprecise pointing, for that employing PID (Proportional Integral Derivative) with tracking mode controller to compensate the hysteresis. PID control system is played a decisive role with tracking mode model that achieves the aim behind the construction of the experimental rig. Good results have been obtained presented in three cases of drawing different shapes.
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Zhao, Ying, and Minoru Taya. "Analytical Modeling for Stress-Strain Curve of a Porous NiTi." Journal of Applied Mechanics 74, no. 2 (2006): 291–97. http://dx.doi.org/10.1115/1.2198250.
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Two models for predicting the stress-strain curve of porous NiTi under compressive loading are presented in this paper. Porous NiTi shape memory alloy is considered as a composite composed of solid NiTi as matrix and pores as inclusions. Eshelby’s equivalent inclusion method and Mori-Tanaka’s mean-field theory are employed in both models. Two types of pore connectivity are investigated. One is closed cells (model 1); the other is where the pores are interconnected to each other forming an open-cell microstructure (model 2). We also consider two different shapes of pores, spherical and ellipsoidal. The stress-strain curves of porous shape memory alloy with spherical pores and ellipsoidal pores are compared. It is found that the ellipsoidal shape assumption is more reasonable than the assumption of spherical pores. Comparison of the stress-strain curves of the two models shows that use of open-cell microstructure (model-2) makes the predictions more agreeable to the experimental results of porous NiTi whose microstructure exhibits open-cell microstructure.
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Khismatullin, Arthur, Oleg Panchenko, Dmitry Kurushkin, Ivan Kladov, and Anatoly Popovich. "Functional and Mechanical Properties of As-Deposited and Heat Treated WAAM-Built NiTi Shape-Memory Alloy." Metals 12, no. 6 (2022): 1044. http://dx.doi.org/10.3390/met12061044.
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In this work, MIG process was utilized for the wire arc additive manufacturing of the wall-shaped parts, using NiTi shape-memory alloy. High-scale specimens consisting of 20 layers were deposited by using Ni-rich (Ni55.56Ti wt.%) wire as a feedstock on the NiTi substrate with the identical chemical composition. One of two specimens was heat-treated at a temperature of 430 °C for 1 h. The influence of such a heat treatment on the microstructure, phase transformation temperatures, chemical and phase compositions, microhardness, and tensile and bending tests’ results is discussed. As-deposited metal successfully demonstrates superelastic behavior, except in the lower zone. In regard to the shape-memory effect, it was concluded that both the as-deposited and the heat-treated samples deformed in liquid nitrogen completely restored (100%) their shapes at an initial strain of 4–5%. An occurrence of the R-phase was found in both the as-deposited and the heat-treated specimens. The phase transformation temperatures, microstructure, and tensile and bending tests results were found to be anisotropic along the height of the specimens. The presented heat treatment led to changes in the functional and mechanical properties of the specimen, provided with the formation of finely dispersed Ni4Ti3, NiTi2, and Ni3Ti phases.
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Uthira Kumar, B., D. S. Robinson Smart, M. Ramachandran, and Vimala Saravanan. "Influence of Chemical Treatment of Natural Fibre using Shape Memory Alloy for Aeronautics." Journal on Electronic and Automation Engineering 2, no. 2 (2023): 11–19. http://dx.doi.org/10.46632/jeae/2/2/4.
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This article offers a thorough review of shape memory alloys' (SMAs') uses in the Space research field. The utility of SMAs in a variety of applications, including morphing wings (using both experimental and modelling methods), customising orientation and inlet shapes for various propulsion systems, implementing flexible chevrons to improve thrust while lowering noise, and reducing overall power consumption, is the main topic of this paper. The use of SMAs in applications in space is also covered in the paper, including how they may be used to create low-shock launchers, isolate micro-vibrations, and enable self-deployable solar sails. The essay also emphasises the novel structures and tools made possible by SMAs. One noteworthy method covered in the article is putting SMA wires in the laminate's midplane and embedding them into the fabric a layer of composite laminates. When compared to traditional composite constructions, the incorporation of SMAs into composite has shown better damage resistance and ductility. The reaction of a bright hybrid plastic composite plates to a very low-velocity impact is examined experimentally and numerically in this paper, which highlights the benefits of inserting SMA wires. Among these benefits are improved damage resistance, better ductility, higher composite hardness, and increased energy absorption before failure. Shape memory alloy (SMA) are the subject of extensive industrial applications and ongoing study in the field of materials. Its two distinguishing qualities, the shape memory impact and superelasticity, are mostly to blame for this. A composition's structure that suffered a phase transition as a result of temperatures, pressures, mechanical forces, and other factors is implies to as having a "shape memory effect". The composition, despite the very significant plastic deformation to which its surface is susceptible to, may recover to its original form under the influence of temperature as well as other factors.
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Shin, Jin, Ye-Ji Han, Ju-Hee Lee, and Min-Woo Han. "Shape Memory Alloys in Textile Platform: Smart Textile-Composite Actuator and Its Application to Soft Grippers." Sensors 23, no. 3 (2023): 1518. http://dx.doi.org/10.3390/s23031518.
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In recent years, many researchers have aimed to construct robotic soft grippers that can handle fragile or unusually shaped objects without causing damage. This study proposes a smart textile-composite actuator and its application to a soft robotic gripper. An active fiber and an inactive fiber are combined together using knitting techniques to manufacture a textile actuator. The active fiber is a shape memory alloy (SMA) that is wire-wrapped with conventional fibers, and the inactive fiber is a knitting yarn. A knitted textile structure is flexible, with an excellent structure retention ability and high compliance, which is suitable for developing soft grippers. A driving source of the actuator is the SMA wire, which deforms under heating due to the shape memory effect. Through experiments, the course-to-wale ratio, the number of bundling SMA wires, and the driving current value needed to achieve the maximum deformation of the actuator were investigated. Three actuators were stitched together to make up each finger of the gripper, and layer placement research was completed to find the fingers’ suitable bending angle for object grasping. Finally, the gripping performance was evaluated through a test of grasping various object shapes, which demonstrated that the gripper could successfully lift flat/spherical/uniquely shaped objects.
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Tarnowski, Michał, Justyna Witkowska, Jerzy Morgiel, et al. "Formation of Nitrogen Doped Titanium Dioxide Surface Layer on NiTi Shape Memory Alloy." Materials 14, no. 6 (2021): 1575. http://dx.doi.org/10.3390/ma14061575.
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NiTi shape memory alloys are increasingly being used as bone and cardiac implants. The oxide layer of nanometric thickness spontaneously formed on their surface does not sufficiently protect from nickel transition into surrounding tissues, and its presence, even in a small amount, can be harmful to the human organism. In order to limit this disadvantageous phenomenon, there are several surface engineering techniques used, including oxidation methods. Due to the usually complex shapes of implants, one of the most prospective methods is low-temperature plasma oxidation. This article presents the role of cathode sputtering in the formation of a titanium dioxide surface layer, specifically rutile. The surface of the NiTi shape memory alloy was modified using low-temperature glow discharge plasma oxidation processes, which were carried out in two variants: oxidation using an argon + oxygen (80% vol.) reactive atmosphere and the less chemically active argon + air (80% vol.), but with a preliminary cathode sputtering process in the Ar + N2 (1:1) plasma. This paper presents the structure (STEM), chemical composition (EDS, SIMS), surface topography (optical profilometer, Atomic Force Microscopy—AFM) and antibacterial properties of nanocrystalline TiO2 diffusive surface layers. It is shown that prior cathodic sputtering in argon-nitrogen plasma almost doubled the thickness of the produced nitrogen-doped titanium dioxide layers despite using air instead of oxygen. The (TiOxNy)2 diffusive surface layer showed a high level of resistance to E. coli colonization in comparison with NiTi, which indicates the possibility of using this surface layer in the modification of NiTi implants’ properties.
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Alhamdi, Ismail, Anwar Algamal, Abdalmageed Almotari, Majed Ali, Umesh Gandhi, and Ala Qattawi. "Fe-Mn-Al-Ni Shape Memory Alloy Additively Manufactured via Laser Powder Bed Fusion." Crystals 13, no. 10 (2023): 1505. http://dx.doi.org/10.3390/cryst13101505.
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Fe-Mn-Al-Ni is an Fe-based shape memory alloy (SMA) featuring higher stability and low temperature dependency of superelasticity stress over a wide range of temperatures. Additive manufacturing (AM) is a promising technique for fabricating Fe-SMA with enhanced properties, which can eliminate the limitations associated with conventional fabrication and allow for the manufacture of complicated shapes with only a single-step fabrication. The current work investigates the densification behavior and fabrication window of an Fe-Mn-Al-Ni SMA using laser powder bed fusion (LPBF). Experimental optimization was performed to identify the optimum processing window parameters in terms of laser power and scanning speed to fabricate Fe-Mn-Al-Ni SMA samples. Laser remelting was also employed to improve the characteristics of Fe-Mn-Al-Ni-fabricated samples. Characterization and testing techniques were carried out to assess the densification behavior of Fe-Mn-Al-Ni to study surface roughness, density, porosity, and hardness. The findings indicated that using a laser power range of 175–200 W combined with a scanning speed of 800 mm/s within the defined processing window parameters can minimize the defects with the material and lead to decreased surface roughness, lower porosity, and higher densification.
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Liu, Mingfang, Lina Hao, Wei Zhang, and Zhirui Zhao. "A novel design of shape-memory alloy-based soft robotic gripper with variable stiffness." International Journal of Advanced Robotic Systems 17, no. 1 (2020): 172988142090781. http://dx.doi.org/10.1177/1729881420907813.
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Soft robotic grippers with compliance have great superiority in grabbing objects with irregular shape or fragility compared with traditional rigid grippers. The main limitations of such systems are small grasping force resulted from properties of soft actuators and lacking variable stiffness of soft robotic grippers, which prevent them from a larger wide range of applications. This article proposes a shape-memory alloy (SMA)-based soft gripper with variable stiffness composed of three robotic fingers for grasping compliantly at low stiffness and holding robustly at high stiffness. Each robotic finger mainly consisted of stiff parts and two variable stiffness joints is installed on the base with a specific angle. The paraffin as a variable stiffness material in the joint can be heated or cooled to change the stiffness of the robotic fingers. Results of experiments have shown that a single robotic finger can approximately achieve 18-fold stiffness enhancement. Each finger with two joints can actively achieve multiple postures by both changing the corresponding stiffness of joints and actuating the SMA wire. Based on these principles, the gripper can be applied to grasp objects with different shapes and a large range of weights, and the maximum grasping force of the gripper is increased to about 10 times using the variable stiffness joints. The final experiment is conducted to validate variable stiffness of the proposed soft grippers grasping an object.
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Komarov, Victor, Roman Karelin, Irina Khmelevskaya, et al. "Evolution of Structure and Properties of Nickel-Enriched NiTi Shape Memory Alloy Subjected to Bi-Axial Deformation." Materials 16, no. 2 (2023): 511. http://dx.doi.org/10.3390/ma16020511.
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The effect of a promising method of performing a thermomechanical treatment which provides the nanocrystalline structure formation in bulk NiTi shape memory alloy samples and a corresponding improvement to their properties was studied in the present work. The bi-axial severe plastic deformation of Ti-50.7at.%Ni alloy was carried out on the MaxStrain module of the Gleeble system at 350 and 330 °C with accumulated true strains of e = 6.6–9.5. The obtained structure and its mechanical and functional properties and martensitic transformations were studied using DSC, X-ray diffractometry, and TEM. A nanocrystalline structure with a grain/subgrain size of below 80 nm was formed in bulk nickel-enriched NiTi alloy after the MaxStrain deformation at 330 °C with e = 9.5. The application of MaxStrain leads to the formation of a nanocrystalline structure that is characterized by the appearance of a nano-sized grains and subgrains with equiaxed and elongated shapes and a high free dislocation density. After the MaxStrain deformation at 330 °C with e = 9.5 was performed, the completely nanocrystalline structure with the grain/subgrain size of below 80 nm was formed in bulk nickel-enriched NiTi alloy for the first time. The resulting structure provides a total recoverable strain of 12%, which exceeds the highest values that have been reported for bulk nickel-enriched NiTi samples.
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SEMBA, HIROMASA, NAGATOSHI OKABE, TORU YAMAJI, KEISUKE OKITA, and KIYOSHI YAMAUCHI. "DYNAMIC BEHAVIOR OF SINGLE-STAGE BELLOWS OF TITANIUM-NICKEL SHAPE MEMORY ALLOY UNDER CYCLIC LOADING." International Journal of Modern Physics B 20, no. 25n27 (2006): 3944–49. http://dx.doi.org/10.1142/s0217979206040635.
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The dynamic behavior of TiNi shape memory alloy (SMA) bellows is examined in light of its potential use as elements in seismic protection devices. Dynamic property results obtained from cyclic tests under tension-compression loading of TiNi SMA single-stage bellows, with different shapes and with different heat treatments, are reported as a function of displacement amplitude and frequency. It was found that the displacement–force loops were almost symmetric with respect to the central point for almost all specimens. The normalized secant stiffness diminishes significantly with increasing bulge height as well as displacement amplitude. From hysteretic cycles, an equivalent damping of about 15% was recognized for longtime-aged bellows with relatively high bulge height. Frequencies, in the range of interest for seismic applications, had a small influence on damping values. Under the conditions studied in this research, the bellows had better damping performance in a martensite phase than in a rhombohedral phase. SMA bellows in martensite phase subjected to the longtime-ageing have great potential as an element in seismic devices.
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Hamed, Nagham M., and Saeed Naif Turki Al-Rashid. "Synthesis, Structure and Optical Properties of NiTi Shape Memory Thin Films." International Journal of Nanoscience 20, no. 02 (2021): 2150015. http://dx.doi.org/10.1142/s0219581x21500150.
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NiTi Shape Memory Alloy (SMA) is now widely used in important applications due to its shape memory effect (SME) and biocompatibility. However, there is still a challenge to control the sizes and shapes of these nanoparticles. Here, we report on the use of pulsed laser deposition technique for the cultivation of NiTi nanoparticles on glass substrates. It discussed the implications of the case of the influence of depositing laser energy on the size of a grain of NiTi nanoparticle. The nominated effect on the optical properties of its thin-film was also discussed. X-ray diffraction (XRD) analysis revealed that the films prepared at 800[Formula: see text]mJ, 900[Formula: see text]mJ and 1000[Formula: see text]mJ were amorphous structures. The Atomic Force Microscopy (AFM) results confirmed that the thin films are made up of spherical particles that are evenly distributed (in terms of size). A blueshift in the bandgap was observed in the UV–Visible absorption spectra with increase in the depositing laser energy due to the quantum confinement effect of nanoparticle formation.
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Mahesh, K. K., and F. M. Braz Fernandes. "Phase transformations in Ni-Ti SMA spring." Journal of Physics: Conference Series 2603, no. 1 (2023): 012017. http://dx.doi.org/10.1088/1742-6596/2603/1/012017.
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Abstract Equi-atomic Nickel-Titanium (Ni-Ti) alloy is one of the prominent materials to exhibit two way shape memory effect (TWSME). Since the material by itself can change shape due to variation in temperature, it is also used as an actuator. In the present study, Ni-Ti (49.5at%Ni-Ti) alloy wire is converted into a spring coil with straight portions on either ends by shape setting. Training is provided to the spring coil portion to achieve TWSME. Separate specimens from the spring and straight portions were extracted. Phase transformations were observed in the spring and straight portions during heating and cooling. Phase transformation behaviour of the spring coil and straight portions were studied using differential scanning calorimetry (DSC). The straight portion undergoes simple thermal cycles. But the spring coil portion undergoes thermomechanical (TM) cycles due to change in shapes during heating and cooling. The thermograms obtained show difference in their nature of phase transformations. Discussion focusses on the difference in the thermograms appearing for the specimens from straight and coil portions.
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Zhang, Qin, Liang Xu, Hao Chen, Zhou Li, Liwu Huang, and Sicheng Yi. "Research on a Novel Shape-Memory Alloy Artificial Muscle with Active and Passive Heat Dissipation." Actuators 14, no. 5 (2025): 248. https://doi.org/10.3390/act14050248.
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Due to their high energy density and favorable load-to-weight ratio, shape-memory alloy (SMA) materials are ideal actuation sources for soft robots. However, the relatively long cooling time of SMA wires in soft bodies limits their response speed. In this study, we designed and fabricated a novel SMA artificial muscle. When active heat absorption was enabled through thermoelectric modules and the evaporation/dehydration effects of hydrogels, the cooling rate of the SMA wires increased significantly. Simulation and experimental results demonstrate that with the proposed heat-dissipation scheme, the cooling speed of the SMA wires improved notably, with a temperature drop of 9.6 °C within 4 s. Additionally, the designed agar/polyacrylamide hydrogel, which has a porous skeleton structure, achieved a water-absorption expansion rate that was 600% of the previous value. When a PVC elastic substrate was used, the bending angle of the SMA artificial muscle reached 71°, with minimal bending attenuation after 45 consecutive cyclic tests. A soft gripper composed of the novel SMA artificial muscles was capable of manipulating objects of various shapes. Overall, the combination of active and passive heat-dissipation strategies enabled the SMA artificial muscle to achieve excellent durability, rapid heat dissipation, and strong versatility, demonstrating its significant potential for various applications.
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Pinter, Pascal, Andreas Reeb, and Kay André Weidenmann. "The Influence of Stress and Heat on the Transformation Behaviour of NiTi for Actuator Applications in Extruded Aluminium Matrix Composites." Materials Science Forum 825-826 (July 2015): 205–12. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.205.
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The integration of functions in lightweight structures features great potential for future applications in diagnosis and control. The combination of shape memory wires or ribbons made of NiTi embedded in aluminium and manufactured by composite extrusion offers the possibility to produce a composite actuator material in a single production step. The extrusion process allows a wide range of shapes and provides higher versatility than actuators made of bi-metals. The transformation temperature of NiTi varies depending on the composition of the alloy, between -100 °C and 100 °C. However, NiTi can also transform stress-induced. In the designated application, a force is applied via the interface onto the matrix material to deform it. Due to the resulting stress, the transformation temperature rises to temperatures higher than those of the unloaded material. Furthermore the production of composite extrusions leads to a significant heat input on the shape memory alloys followed by another increase of the transformation temperature.Therefore it is essential to reproduce the heat treatment and the stress-induced transformation to predict the transformation temperature in the resulting composite influenced by the interface. For that purpose, the wire gets annealed in a furnace with different durations at a temperature similar to that of the bar extrusion process. After this, the transformation temperatures can be observed at various stresses to evaluate their applicability for aluminium composite actuators.
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Sun, Longfei, Yiwen Lan, and Binghao Wang. "Anthropomorphic modular gripper finger actuated by antagonistic wire and shape-memory alloy (SMA) springs." Mechanical Sciences 15, no. 2 (2024): 601–11. http://dx.doi.org/10.5194/ms-15-601-2024.
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Abstract. The traditional underactuated grippers can only passively adapt to the contour of the object, and the passive contact process may lead to the object slipping, affecting the stability of the grasping process. In this paper, an anthropomorphic modular gripper finger actuated by antagonistic wire and shape-memory alloy (SMA) springs, which can actively control the grasping morphology according to the characteristics of the objects to be grasped, is proposed. The wire drive simulates the flexor muscle, and the SMA and reset springs simulate the extensor muscles of the finger, which antagonistically control the grasping morphology of the finger. It is more in line with the grasping characteristics of the human hand. According to the moment equilibrium principle of the finger joints, the deformation model of the gripper is established, the influence of the wire tension and the equivalent stiffness of the finger joints on the grasping morphology is analyzed, and the theoretical joint angle results are verified by the Adams simulation; finally, the experimental system of the gripper is constructed, and the verification of the deformation morphology of the single finger and the gripper's enveloping–grasping experiments is completed. The results show that according to the contour size of the object, by actively controlling the wire force of the gripper and the equivalent stiffness of the interphalangeal joints, the enveloping–grasping action of different objects can be completed and the stable grasping of objects of different shapes and sizes can be realized.
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Löffler, Robin, Stephan Tremmel, and Rüdiger Hornfeck. "Owl-Neck-Spine-Inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators." Biomimetics 8, no. 1 (2023): 117. http://dx.doi.org/10.3390/biomimetics8010117.
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Nature provides a considerable number of good examples for simple and very efficient joint assemblies. One example is the enormously flexible cervical spine of American barn owls, which consists of 14 cervical vertebrae. Each pair of vertebrae produces a comparatively small individual movement in order to provide a large overall movement of the entire cervical spine. The biomimetic replication of such joints is difficult due to the delicate and geometric unrestricted joint shapes as well as the muscles that have to be mimicked. Using X-ray as well as micro-computed tomography images and with the utilisation of additive manufacturing, it was possible to produce the owl neck vertebrae in scaled-up form, to analyse them and then to transfer them into technically usable joint assemblies. The muscle substitution of these joints was realised by smart materials actuators in the form of shape memory alloy wire actuators. This actuator technology is outstanding for its muscle-like movement and for its high-energy density. The disadvantage of this wire actuator technology is the low rate of contraction, which means that a large length of wire has to be installed to generate adequate movement. For this reason, the actuator wires were integrated into additively manufactured carrier components to mimic biological joints. This resulted in joint designs that compensate for the disadvantages of the small contraction of the actuators by intelligently installing large wire lengths on comparatively small installation spaces, while also providing a sufficient force output. With the help of a test rig, the developed technical joint variants are examined and evaluated. This demonstrated the technical applicability of this biomimetic joints.
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Chen, Xi, Lars Bumke, Eckhard Quandt, and Manfred Kohl. "Bistable Actuation Based on Antagonistic Buckling SMA Beams." Actuators 12, no. 11 (2023): 422. http://dx.doi.org/10.3390/act12110422.
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Novel miniature-scale bistable actuators are developed, which consist of two antagonistically coupled buckling shape memory alloy (SMA) beams. Two SMA films are designed as buckling SMA beams, whose memory shapes are adjusted to have opposing buckling states. Coupling the SMA beams in their center leads to a compact bistable actuator, which exhibits a bi-directional snap-through motion by selectively heating the SMA beams. Fabrication involves magnetron sputtering of SMA films, subsequent micromachining by lithography, and systems integration. The stationary force–displacement characteristics of monostable actuators consisting of single buckling SMA beams and bistable actuators are characterized with respect to their geometrical parameters. The dynamic performance of bistable actuation is investigated by selectively heating the SMA beams via direct mechanical contact to a low-temperature heat source in the range of 130–190 °C. The bistable actuation is characterized by a large stroke up to 3.65 mm corresponding to more than 30% of the SMA beam length. Operation frequencies are in the order of 1 Hz depending on geometrical parameters and heat source temperature. The bistable actuation at low-temperature differences provides a route for waste heat recovery.
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Bhagwatkar, Deepti, Faseeh Muhammed Bin Farookh, Bellamkonda Neeha Pavithra, Wajeeda Tabassum, Piyush Tiwari, and Bhawna Garg. "Nitinol advancements in endodontics: Heat treatment and surface functionalization of NiTi instruments." IP Indian Journal of Conservative and Endodontics 8, no. 3 (2023): 150–54. http://dx.doi.org/10.18231/j.ijce.2023.028.
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Nitinol, a nickel-titanium alloy known for its exceptional properties of shape memory, superelasticity, and biocompatibility, has revolutionized the field of endodontics. This article explores the evolutionary journey of Nitinol in endodontics, highlighting its historical inception and subsequent integration into dental instruments. The article delves into pivotal advancements such as heat treatment and surface functionalization, showcasing their transformative effects on the mechanical properties and biocompatibility of Nitinol instruments. The discussion encompasses terms related to NiTi file design, including helical flute angles, pitch, cutting edges, rake angles, radial lands, cross-sectional shapes, and taper. Moreover, the article elucidates the modes of movement employed by NiTi files, including continuous rotary motion, reciprocating motion, and axial motion, emphasizing their significance in enhancing precision and minimizing risks. Through an exploration of Nitinol's evolution and its impact on endodontic procedures, this article underscores the symbiotic relationship between innovative materials and the evolving landscape of dentistry.
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Khalil, Ahmed Mohsen, Mohamed Elkafrawy, Rami Hawileh, and Mohammad Al-Hamaydeh. "Numerical Investigation on Improving Shear Strength of RC Beams with Various Web Opening Shapes Using Pre-Stressed Fe-SMA Bars." Key Engineering Materials 1004 (December 23, 2024): 13–22. https://doi.org/10.4028/p-e2xiev.
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The presence of web openings in the shear span significantly impacts the structural behavior of reinforced concrete (RC) beams, affecting both shear capacity and crack propagation. This study explores the feasibility of strengthening web openings in the shear zone of RC beams using iron-based shape memory alloy (Fe-SMA) bars through numerical analysis with ABAQUS software. The investigation considered various web opening shapes; diamond, circular, and square strengthened with pre-stressed Fe-SMA bars. Results showed that web openings notably decrease the ultimate loads of beams by 53%, 44%, and 39% for square, circular, and diamond shapes, respectively. However, pre-stressed Fe-SMA bars enhanced the shear capacity of beams with unstrengthened web openings by approximately 60%, making their behavior comparable to solid beams. The proposed strengthening technique was most effective for diamond web openings, nearly restoring both shear strength and stiffness, while circular openings recovered nearly 90% of shear capacity and square openings about 75%. Additionally, Fe-SMA bars effectively controlled cracking at the corners of the openings. This study highlights the importance of strengthening web openings in RC beams, especially in shear zones, and provides significant insights into enhancing such beams, contributing to safer structural designs. Further laboratory experiments are recommended to validate and extend these numerical findings.
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Su, X., and M. P. Cartmell. "Modifications to the response of a parametrically excited cantilever beam by means of smart active elements." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, no. 8 (2009): 1579–91. http://dx.doi.org/10.1243/09544062jmes1956.
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This article is concerned with applying active smart material elements for modifying parametric vibration in a flexible composite beam structure. The glass epoxy beam is bonded to two theoretically prestrained shape memory alloy (SMA) strips and fitted with a lumped end mass. In this study, the components of the recovery force generated during the SMA activation are derived with respect to a three-dimensional frame when the structure is undergoing combined bending and torsional motions. In order to employ Lagrangian dynamics, the generalized forces are formulated and the equations of motion are then derived. Three different parametric resonances for the structure are predicted by using the multiple scales perturbation method. In addition, the effects of the SMA strips on the natural frequencies, the mode shapes, and the instability regions of the structure are all investigated. It is shown that the different thresholds of instability for parametric resonances within a composite structure of this sort may be influenced by smart active elements.
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Benarrait, Racha, Muneeb Ullah-Khan, Jérémy Terrien, Hani Al Hajjar, Frédéric Lamarque, and Andreas Dietzel. "A Flexible Double-Sided Curvature Sensor Array for Use in Soft Robotics." Sensors 24, no. 11 (2024): 3475. http://dx.doi.org/10.3390/s24113475.
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This paper describes the design, fabrication, integration, characterization, and demonstration of a novel flexible double-sided curvature sensor array for use in soft robotics. The paper explores the performance and potential applications of a piezoresistive sensor array consisting of four gold strain gauges on a flexible polyimide (PI) substrate arranged in a Wheatstone bridge configuration. Multiple sensor strips were arranged like the fingers of a hand. Integrating Shape Memory Alloy (SMA) foils alongside the fingers was explored to mimic a human hand-gripping motion controlled with temperature, while curvature sensor array strips measure the resulting finger shapes. Moreover, object sensing in a flexible granular material gripper was demonstrated. The sensors were embedded within Polydimethylsiloxane (PDMS) to enhance their tactile feel and adhesive properties. The findings of this study are promising for future applications, particularly in robotics and prosthetics, as the ability to accurately mimic human hand movements and reconstruct sensor surfaces paves the way for robotic hand functionality.
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Liu, Hongwei, Jiong Wang, and Hui-Hui Dai. "Analytical study on stress-induced phase transitions in geometrically graded shape memory alloy layers. Part II: Analyses on geometrical shapes, loading procedures and boundary conditions." Mechanics of Materials 112 (September 2017): 114–28. http://dx.doi.org/10.1016/j.mechmat.2017.05.014.
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Paton, B. E., D. M. Kaleko, S. N. Kedrovsky, Yu N. Koval, I. V. Krivtsun, and V. N. Slepchenko. "Resistance welding of shape-memory copper-aluminium alloy." Paton Welding Journal 2015, no. 12 (2015): 2–7. http://dx.doi.org/10.15407/tpwj2015.12.01.
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Nes, Cristian Sorin, Angelica Enkelhardt, Nicolae Faur, and Adrian Birlan. "Numerical Stress Intensity Factors Determination for Fabrication Defects in Coronary Stents." Key Engineering Materials 488-489 (September 2011): 718–21. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.718.
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Objectives: Numerical stress intensity factors (SIFs) computation for several fabrication defect geometries in coronary stents. XFEM crack initiation and propagation was also performed. Methods: The model represents a self-expandable coronary stent, made from a shape memory alloy (L-605). Several flaw shapes are considered. The analysis was performed using the ABAQUS code. The loads and boundary conditions simulate the interaction between the blood vessels and stents, immediately after the angioplasty was performed. The mesh contains 3d stress hexahedral elements. For global stress and strain distributions, the model of a complete stent was used. For crack propagation analysis and SIF determination, the model represented a single segment of the stent. The stress intensity factors were computed using the contour integral method. Results and conclusions: The stress and strain fields highlight the negative effects of crack initiation and propagation on the residual life of the stent. Furthermore, by compromising the structural integrity of the stent, large strains may occur, thus increasing the risk of restenosis and further stenosis-related complications. The stress intensity factors indicate the most dangerous locations for the flaws (cracks), as well as the most dangerous geometries.
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MORALES S., Marcia, Hisaaki TOBUSHI, Kousuke DATE, and Kouji MIYAMOTO. "654 Bending Fatigue Properties of TiNi Shape Memory Alloy." Proceedings of Conference of Tokai Branch 2010.59 (2010): 373–74. http://dx.doi.org/10.1299/jsmetokai.2010.59.373.
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Perez-Sanchez, Vicente, Francisco Javier Garcia-Rubiales, Saeed Rafee Nekoo, Begoña Arrue, and Anibal Ollero. "Modeling and Application of an SMA-Actuated Lightweight Human-Inspired Gripper for Aerial Manipulation." Machines 11, no. 9 (2023): 859. http://dx.doi.org/10.3390/machines11090859.
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The increasing usage of multi-rotor aerial platforms and the reliability of flights enabled researchers to add equipment and devices to them for application. The addition of lightweight manipulators, grippers, and mechanisms to fulfill specific tasks has been reported frequently recently. This work pushes the idea one step ahead and uses an Artificial Human Hand (AHH) in an uncrewed aerial vehicle for aerial manipulation, device delivery, and co-operation with human workers. This application requires an effective end-effector capable of grasping and holding objects of different shapes. The AHH is a lightweight custom-made human-inspired design actuated using Shape Memory Alloy (SMA) materials. The SMA actuators offer significantly high forces with respect to their light weights though the control of these new actuators is a challenge that has been successfully demonstrated in this paper. The control of the SMA actuators could be achieved via heat exchange on the actuator, indirectly carried out by changing the current. The benefit of using this new actuator is removing the motors and mechanical mechanisms and simplifying the design. A soft cover is developed for the AHH to add friction and make it closer to a human hand. The modeling of the structured actuators on the system through tendons is presented, and a series of experiments for handling and manipulating different objects have been conducted. The objects were chosen with different weights and shapes to show the effectiveness of the design. An analysis of a generated torque of the manipulator for different cylindrical objects has been carried out. An analysis and comparison for grasping a series of items, pressure and temperature analysis, and the weight-to-volume ratio have been presented.
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Ishida, Tohru, and Yoshimi Takeuchi. "Design and Implementation of Automatic Discharge Gap Controller for a Curved Hole Creating Microrobot with an Electrical Discharge Machining Function." International Journal of Automation Technology 4, no. 6 (2010): 542–51. http://dx.doi.org/10.20965/ijat.2010.p0542.
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This study deals with the development of a mechanism which can autonomously and automatically control the discharge gap for achieving electrical discharge machining (EDM) in an almost isolated space. This is so that a microrobot equipped with the mechanism can create a long, complicated curved hole, a hole that could not be formed by conventional machining methods. Holes formed by conventional machining methods are generally straight, so pipelines built in a variety of mechanical apparatuses consist of straight or polygonal lines. Such dearth of variety in realizable hole shapes can sometimes cause fundamental problems. A typical example of the problems appears in the design and production of water channels, i.e., pipelines built in metal molds to achieve appropriate thermal controls in molding processes. Specifically, the low variety of hole shapes prevents the shapes and positions of water channels from being optimized for the best thermal control in molding. Therefore, the development of a new method for machining curved holes has been needed. To meet this needed, we have conceived a method of machining curved holes by employing a microrobot that can perform EDM. A long, complicated curved hole can be created by making the microrobot perform stable EDM while moving along a long, complicated, curved trajectory in a workpiece. In order to realize this concept, the microrobot must have the capability to autonomously and automatically control the discharge gap in such an almost isolated space as the bottom or end of a curved hole. Accordingly, this study devises a new mechanism to give the microrobot this capability, and it calls the mechanism the “automatic discharge gap controller” (ADGC). The main components of ADGC are an electrode and power supply for EDM and a bidirectional actuator in which shape memory alloy (SMA) is employed. The results obtained from the experiments using a prototype of the ADGC prove that the ADGC has the capability of performing stable EDM by controlling the discharge gap autonomously and automatically without any other actuators.
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Wheat, C. Geoffrey, Christopher Kitts, Camden Webb, et al. "A new high-temperature borehole fluid sampler: the Multi-Temperature Fluid Sampler." Scientific Drilling 28 (December 1, 2020): 43–48. http://dx.doi.org/10.5194/sd-28-43-2020.
Full textAbstract:
Abstract. Deep (>1 km depth) scientific boreholes are unique assets that can be used to address a variety of microbiological, hydrologic, and biogeochemical hypotheses. Few of these deep boreholes exist in oceanic crust. One of them, Deep Sea Drilling Project Hole 504B, reaches ∼190 ∘C at its base. We designed, fabricated, and laboratory-tested the Multi-Temperature Fluid Sampler (MTFS), a non-gas-tight, titanium syringe-style fluid sampler for borehole applications that is tolerant of such high temperatures. Each of the 12 MTFS units collects a single 1 L sample at a predetermined temperature, which is defined by the trigger design and a shape memory alloy (SMA). SMAs have the innate ability to be deformed and only return to their initial shapes when their activation temperatures are reached, thereby triggering a sampler at a predetermined temperature. Three SMA-based trigger mechanisms, which do not rely on electronics, were tested. Triggers were released at temperatures spanning from 80 to 181 ∘C. The MTFS was set for deployment on International Ocean Discovery Program Expedition 385T, but hole conditions precluded its use. The sampler is ready for use in deep oceanic or continental scientific boreholes with minimal training for operational success.
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Sun, Longfei, and Huiying Gu. "Envelope Morphology of an Elephant Trunk-like Robot Based on Differential Cable–SMA Spring Actuation." Actuators 14, no. 2 (2025): 100. https://doi.org/10.3390/act14020100.
Full textAbstract:
Most trunk-like robots are designed with distributed actuators to mimic the envelope-grasping behavior of elephant trunks in nature, leading to a complex actuation system. In this paper, a modular underactuated elephant trunk-imitating robot based on the combined drive of the cable and shape memory alloy (SMA) springs is designed. Unlike the traditional underactuated structure that can only passively adapt to the envelope of the object contour, the proposed elephant trunk robot can control the cable tension and the equivalent stiffness of the SMA springs to achieve active control of the envelope morphology for different target objects. The overall structure of the elephant trunk robot is designed and the principle of deformation envelope is elucidated. Based on the static model of the robot under load, the mapping relationship between the tension force and the tension angle between modules is derived. The positive kinematic model of the elephant trunk robot is established based on the Debavit–Hartenberg (D–H) method, the spatial position of the elephant trunk robot is obtained, and the Monte Carlo method is used to derive the robot’s working space. The active bending envelope grasping performance is further verified by building the prototype to perform grasping experiments on objects of various shapes.