Dissertations / Theses on the topic 'Shape Memory Alloy Actuators'
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Lafontaine, Serge R. "Fast shape memory alloy actuators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/NQ44482.pdf.
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Lafontaine, Serge R. "Fast shape memory alloy actuators." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34990.
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In this thesis techniques for fabricating fast contracting and relaxing shape memory alloy (SMA) fibers are presented. Shape memory alloy fibers have demonstrated the largest stress and highest power to mass ratio of any known actuator technology. However their practical application has been plagued by three major drawbacks, namely: (1) relatively slow expansion of the material despite rapid contraction; (2) problems of mechanically and electrically connecting to the material due to the violent nature of their contractions; and (3) low efficiency in the conversion of electrical energy or heat into mechanical energy. The work associated with this thesis has led to solutions to the first two problems allowing even sub-millisecond contraction-expansion cycle times, and fibers to be attached via light weight but high strength and high conductivity joints. The properties of these fibers are extensively studied. Both linear and rotary actuators are built using these fibers.A new technique is presented to mount nickel-titanium (NiTi) SMA fibers. NiTi alloys are not readily bonded, soldered, brazed or welded to other materials. The new method employs metal deposited on the fiber or between two fibers or between fibers and other parts, creating metallic attachments that are mechanically sound and electrically conductive. Furthermore a new process for the three-dimensional microfabrication by localized electrodeposition and etching has also been developed. This latter process, combined with the first process, can be used to integrate NiTi alloys in micro-mechanisms. The good electrical contacts as well as mechanical contact provided by the new attachment mechanisms are important, since they allow the rapid methods to be employed.
Several apparatus were built to study the response of NiTi fibers, in particular to very fast current pulses. Experimental results were obtained to describe the response of the fibers, such as their speed, hysteresis, stiffness and resistivity, and show how these variables change dynamically as a function of time, temperature and stress. Other measurements important for the design of new actuators were done, such as those of efficiency when fast actuation with large current pulses is used.
In the third part of the thesis a novel application for fast fiber actuators is presented in the form of a fast rotary motor for in-the-wheel car rotary motors.
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Prothero, Lori Michelle Gross Robert Steven. "Shape memory alloy robotic truss." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Aerospace_Engineering/Thesis/Prothero_Lori_16.pdf.
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Soares, Alcimar Barbosa. "Shape memory alloy actuators for upper limb prostheses." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/21541.
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Despite the technological advances of the twentieth century, we are not yet able to produce artificial limbs which "mimic" perfectly their natural counterparts. In general, artificial limbs are not as dextrous as human limbs, the control is unnatural and there is no proper feedback by which the user can assess the status of the prosthesis. In this thesis the problems related to upper-limb prostheses are considered. The use of a special material known as Shape Memory Alloy (SMA) is investigated towards producing improved joint actuators for small artificial prostheses such as those required by young children. SMA actuators can be very lightweight, their motion is silent and smooth and yet they are capable of delivering considerable power per unit of weight. The Shape Memory phenomenon and the many challenges involved in its application are discussed. The detailed design of an SMA joint actuator for a hand mechanism in an above-elbow prosthesis for young children is given. To assist the design and construction of both the artificial hand and the actuator, a mathematical model was developed and incorporated in a computer program simulating the forces and movements within the hand. The model was used to optimise the hand mechanism and specify the required joint actuator. Suitable SMA elements were identified through laboratory tests. The hand mechanism was constructed and the actuator, control systems and power source were attached to it. Tests were performed to investigate the characteristics of the complete device. The results show that, although SMA actuators must be designed and used with great care, they do offer a viable and more natural alternative to conventional actuators such as pneumatic devices and electric motors in certain applications.
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Grant, Danny. "Accurate and rapid control of shape memory alloy actuators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/NQ55336.pdf.
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Lederlé, Stéphane 1978. "Issues in the design of shape memory alloy actuators." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16830.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002."June 2002."
Includes bibliographical references (p. 93-96).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
This thesis considers the application of shape memory alloy (SMA) actuators for shape control of the undertray of a sports car. By deforming the shape of the structure that provides aerodynamic stability to the car, we expect to improve the overall performance of the vehicle by adapting its aerodynamics according to the vehicle speed. We then develop a methodology for designing SMA actuators in this application. The methodology is based on the integration of the different models involved: mechanical, thermal, and electrical. The constraints imposed on the device are also incorporated. Unfortunately, the analysis predicts an actuation time that is too slow for this particular application. Still, we use our assembled model to sketch the expected characteristics of SMA actuators. A significant result is that the actuation time is a function of the amount of energy the active material has to provide, and that there is a necessary trade-off between the mass of actuators and the actuation time. In particular, the expected energy density may have to be decreased to achieve acceptable actuation times. Finally, we propose a way to estimate a priori the suitability of SMA actuators for a particular application.
by Stéphane Lederlé.
S.M.
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Kumar, Guhan. "Modeling and design of one dimensional shape memory alloy actuators." Connect to resource, 2000. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1116879145.
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Becker, Marcus Patrick. "Thermomechanical training and characterization of shape memory alloy axial actuators." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/becker/BeckerM0510.pdf.
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Although considerable work has been performed to understand the key mechanisms of Shape Memory Alloy (SMA) behavior, little of this work follows a standard testing protocol, quantifies a conditioning methodology, or develops data appropriate for design of SMA actuators. One major issue that limits the ability of the material from being used directly as an actuator is the large, non-recoverable strains likely to accrue in the material during each training cycle, mechanical or thermal. When mechanical or thermal cycling is performed, a hysteresis curve develops and reaches a steady state strain recovery response. At the point where permanent plastic strain stops growing, or saturates, the SMA has been successfully trained. The focus of this work is oriented toward SMAs in general, but all testing and experimentation was carried out on Nickel-Titanium (NiTi) alloys. The experimentation and testing was performed on a combination of 4 different sizes and 3 different NiTi alloy compositions. Thermomechanical testing was performed to determine critical values to describe the stress-temperature phase space of the materials and parameters to model the applied stress and transformation strain relationship. All material size and alloy combinations were tested in the as-received, or as-machined, and fully annealed state. The results of the training and actuation strain characterization process developed in this work shows that the samples that experienced Transformation Induced Plasticity (TRIP), greater than 2% during the training process and exhibit Two-Way Shape Memory (TWSM) after being fully trained, share a very similar applied stress versus transformation strain curve. This curve is modeled by the Back Stress formulation derived from the Gibbs Free Energy constitutive model by Bo & Lagoudas. The design space created by the Back Stress formulation, recrystallization temperature, and training stress allows SMA materials to be characterized and implemented as stable 1-D actuators. This research formalized a thermomechanical training and characterization method for uniaxial SMA actuators by addressing the interaction between processing, recoverable and non-recoverable deformation. Using various sizes and NiTi alloy combinations, this research develops and evaluates a method to train and characterize a diverse range of SMAs through a set of thermomechanical and physical property measurements.
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Nakamura, Mealani 1978. "A torso haptic display based on shape memory alloy actuators." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89927.
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Chambers, Joshua Michael. "Design and characterization of acoustic pulse shape memory alloy actuators." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32378.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 175-177).
Single crystal Ni-Mn-Ga ferromagnetic shape memory alloys (FSMAs) are active materials which produce strain when a magnetic field is applied. The large saturation strain (6%) of Ni-Mn-Ga, and material energy density comparable to piezoelectric ceramics make Ni- Mn-Ga an interesting active material. However, their usefulness is limited by the bulky electromagnet required to produce a magnetic field. In this thesis, a novel actuation method is developed for shape memory alloys in their martensitic phase, whereby asymmetric acoustic pulses are used to drive twin boundary motion. Experimental actuators were developed using a combination of Ni-Mn-Ga FSMA single crystals and a piezoelectric stack actuator. In bi-directional actuation without load, strains of over 3% were achieved using repeated pulses (at 100 Hz) over a 30 s interval, while 1% strain was achieved in under 1 s. The maximum strains achieved are comparable to the strains achieved using bi-directional magnetic actuation, although the time required for actuation is longer. No-load actuation also showed a nearly linear relationship between the magnitude of the asymmetric stress pulse and the strain achieved during actuation, and a positive correlation between pulse repetition rate and output strain rate, up to at least 100 Hz. Acoustic actuation against a spring load showed a maximum output energy density for the actuator of about 1000 J/m³, with a peak-to-peak stress and strain of 100 kPa and 2%, respectively.
by Joshua Michael Chambers.
S.M.
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Liang, Yuanchang. "Design principle of actuators based on ferromagnetic shape memory alloy /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/7072.
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Giles, Adam R. "Deflection and shape change of smart composite laminates using shape memory alloy actuators." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7698.
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Shape memory materials have been known for many years to possess the unique ability of memorising their shape at some temperature. If these materials are pre-strained into the plastic range, they tend to recover their original un-strained shapes via phase transformation when subjected to heat stimulation. In recent years, this shape memory effect (SME) or strain recovery capability has been explored in aerospace structures for actuating the real-time movement of structural components. Among all the shape memory materials, the nickel-titanium based shape memory alloy (SMA) has by far received the most attention because of its high recovery capabilities. Since SMAs are usually drawn into the form of wires, they are particularly suitable for being integrated into fibre-reinforced composite structures. These integrated composite structures with SMA wires are thus called smart adaptive structures. To achieve the SME, these wires are normally embedded in the host composite structures. In returning to their unstrained shape upon heat application, they tend to exert internal stresses on the host composite structures in which they are embedded. This action could result in a controlled change in shape of the structural components. Although there has been a significant amount of research dedicated to characterising and modelling the SME of SMA wires, little experimental work had been done to offer an in-depth understanding of the mechanical behaviour of these smart adaptive polymeric composite structures. This project examined the deflection and shape change of carbon/epoxy and glass/epoxy cantilever beams through heating and cooling of internal nitinol SMA wires/strips. The heat damage mechanism and cyclic behaviour are major factors in the operation of such a system and need to be clearly understood in order to develop and gain confidence for the possible implementation of future smart actuating systems. Therefore, the objectives of the proposed research were to investigate (i) effect of embedding SMA, wires on mechanical properties of host composite, (ii) assessment of single-cycle and multiple-cycle actuation performance of smart beams, and (iii) thermal effects of excessive heat on the surrounding composite matrix.
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Pardon, Gaspard. "A feasibility Study of SMA Powder Composite Actuators." Thesis, KTH, Mikrosystemteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91283.
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Frautschi, Jason Paul. "Finite Element Simulations of Shape Memory Alloy Actuators in Adaptive Structures." NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-03302003-174528/.
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Shape memory alloys possess an inherent actuation capability that makes them attractive as actuators in adaptive structures, especially in applications in which their large strains, high specific work output and potential for structural integration are beneficial. However, the requisite extensive physical testing has slowed development of potential applications and highlighted the need for a simulation tool for feasibility studies. In this study, such a tool has been developed by implementing the Müller-Achenbach-Seelecke shape memory alloy model into a commercial finite element code. The material model is described with particular emphasis on its ability to predict actuatoric performance and suitability for use in the context of a displacement-based finite element framework. The interaction between the material model and the solution algorithm for the global finite element equations is thoroughly investigated with respect to the effect of solution parameters on convergence, computational cost and accuracy. Finally, simulations of several flexible structures actuated by shape memory alloys are presented as examples of the potential of the implementation to analyze practical applications. The implementation represents a versatile and novel tool for the simulation of adaptive structural components using shape memory alloy actuators.
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Rosmarin, Josiah Benjamin. "Design of a humanoid hand using segmented shape memory alloy actuators." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36706.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaf 48).
Despite amazing progress in the past two decades, the field of robotics has yet to produce a robotic hand with the same dexterity as the human hand. There has yet to even be a functioning robotic hand of the same size and weight as the human hand. These deficiencies can be attributed to the size, weight and complexity of the actuators used in these robotic hands. Thermal shape memory alloys (SMA's) have characteristics such as high power density which indicate that they would be ideal actuators for such applications. However, certain characteristics of SMA exist which, if left unaddressed, make usage as an actuator impractical. The implementation of SMA for the actuation of a 20 degree of freedom robotic hand and forearm is investigated. A segmented actuation design for the SMA is implemented to address issues of practicality; other issues with regards to the controllability, response time and limited strain of the SMA are addressed. A 20 degree of freedom robotic hand with 16 controlled axes is designed along with a 32 axis actuator box. The designs are realized and the result is a functioning robotic hand of similar size and weight to the human hand. It is concluded that thermal shape memory alloys are a viable solution for the purposes of compact lightweight actuation of vast degree of freedom systems.
by Josiah Benjamin Rosmarin.
S.B.
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Couch, Ronald Newton. "Development of magnetic shape memory alloy actuators for a swashplateless helicopter rotor." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3526.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Turner, Travis Lee. "Thermomechanical Response of Shape Memory Alloy Hybrid Composites." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29771.
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This study examines the use of embedded shape memory alloy (SMA)actuators for adaptive control of the themomechanical response of composite structures. Control of static and dynamic responses are demonstrated including thermal buckling, thermal post-buckling, vibration, sonic fatigue, and acoustic transmission. A thermomechanical model is presented for analyzing such shape memory alloy hybrid composite (SMAHC) structures exposed to thermal and mechanical loads. Also presented are (1) fabrication procedures for SMAHC specimens, (2) characterization of the constituent materials for model quantification, (3) development of the test apparatus for conducting static and dynamic experiments on specimens with and without SMA, (4) discussion of the experimental results, and (5) validation of the analytical and numerical tools developed in the study.
The constitutive model developed to describe the mechanics of a SMAHC lamina captures the material nonlinearity with temperature of the SMA and matrix material if necessary. It is in a form that is amenable to commercial finite element (FE) code implementation. The model is valid for constrained, restrained, or free recovery configurations with appropriate measurements of fundamental engineering properties. This constitutive model is used along with classical lamination theory and the FE method to formulate the equations of motion for panel-type structures subjected to steady-state thermal and dynamic mechanical loads. Mechanical loads that are considered include acoustic pressure, inertial (base acceleration), and concentrated forces. Four solution types are developed from the governing equations including thermal buckling, thermal post-buckling, dynamic response, and acoustic transmission/radiation. These solution procedures are compared with closed-form and/or other known solutions to benchmark the numerical tools developed in this study.
Practical solutions for overcoming fabrication issues and obtaining repeatable specimens are demonstrated. Results from characterization of the SMA constituent are highlighted with regard to their impact on thermomechanical modeling. Results from static and dynamic tests on a SMAHC beam specimen are presented, which demonstrate the enormous control authority of the SMA actuators. Excellent agreement is achieved between the predicted and measured responses including thermal buckling, thermal post-buckling, and dynamic response due to inertial loading.
The validated model and thermomechanical analysis tools are used to demonstrate a variety of static and dynamic response behaviors associated with SMAHC structures. Topics of discussion include the fundamental mechanics of SMAHC structures, control of static (thermal buckling and post-buckling) and dynamic responses (vibration, sonic fatigue, and acoustic transmission), and SMAHC design considerations for these applications. The dynamic response performance of a SMAHC panel specimen is compared to conventional response abatement approaches. SMAHCs are shown to have significant advantages for vibration, sonic fatigue, and noise control.Ph. D.
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Paine, Jeffrey Steven Nelson. "The performance of nitinol shape memory alloy actuators embedded in thermoplastic composite material systems /." This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10102009-020117/.
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Santiago, Anadón José R. "Large force shape memory alloy linear actuator." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE1001179.
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Stebner, Aaron P. "Development, Characterization, and Application of Ni19.5Ti50.5Pd25Pt5 High-Temperature Shape Memory Alloy Helical Actuators." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1194994008.
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Thesis (M.S.)--University of Akron, Dept. of Mechanical Engineering, 2007."December, 2007." Title from electronic thesis title page (viewed 02/22/2008) Advisor, D. Dane Quinn; Co-Advisor, Graham Kelly; Department Chair, Celal Batur; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Lemanski, Jennifer. "CRYOGENIC SHAPE MEMORY ALLOY ACTUATORS FOR SPACEPORT TECHNOLOGIES: MATERIALS CHARACTERIZATION AND PROTOTYPE TESTING." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2779.
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Shape memory alloys (SMAs) possess the unique ability to change their shape by undergoing a solid-state phase transformation at a particular temperature. The shape change is associated with a large strain recovery as the material returns to its "remembered" shape. Their ability to act as both sensor and actuator has made them an attractive subject of study for numerous applications. SMAs have many characteristics which are advantageous in space-related applications, including generation of large forces associated with the strain recovery, smooth and controlled movements, large movement to weight ratio, high reliability, and spark-free operation. The objective of this work is the further development and testing of a cryogenic thermal conduction switch as part of NASA funded projects. The switch was developed to provide a variable conductive pathway between liquid methane and liquid oxygen dewars in order to passively regulate the methane temperature. Development of the switch concept has been continued in this work by utilizing Ni-Ti-Fe as the active SMA element. Ni-Ti-Fe exhibits the shape memory effect at cryogenic temperatures, which makes it well suited for low temperature applications. This alloy is also distinguished by an intermediate phase change known as the rhombohedral or R-phase, which is characterized by a small hysteresis (typically 1-2 deg C) and offers the advantage of precise control over a set temperature range. For the Ni-Ti-Fe alloy used, its thermomechanical processing, subsequent characterization using dilatometry and differential scanning calorimetry and implementation in the conduction switch configuration are addressed. This work was funded by grants from NASA KSC (NAG10-323) and NASA GRC (NAG3-2751).M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
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Nicholson, Douglas E. "Thermomechanical behavior of high-temperature shape memory alloy Ni-Ti-Pd-Pt actuators." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4814.
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To date the commercial use of shape memory alloys (SMAs) has been mostly limited to binary NiTi alloys with transformation temperatures approximately in the -100 to 100 &"186;C range. In an ongoing effort to develop high-temperature shape memory alloys (HTSMAs), ternary and quaternary additions are being made to binary NiTi to form NiTi-X (e.g., X: Pd, Pt, Au and Hf) alloys. Stability and repeatability can be further increased at these higher temperatures by limiting the stress, but the tradeoff is reduced work output and stroke. However, HTSMAs operating at decreased stresses can still be used effectively in actuator applications that require large strokes when used in the form of springs. The overall objective of this work is to facilitate the development of HTSMAs for use as high-force actuators in active/adaptive aerospace structures. A modular test setup was assembled with the objective of acquiring stroke, stress, temperature and moment data in real time during joule heating and forced convective cooling of Ni19.5Ti50.5Pd25Pt5 HTSMA springs. The spring actuators were evaluated under both monotonic axial loading and thermomechanical cycling. The role of rotational constraints (i.e., by restricting rotation or allowing for free rotation at the ends of the springs) on stroke performance was also assessed. Recognizing that evolution in the material microstructure results in changes in geometry and vice versa in HTSMA springs, the objective of the present study also included assessing the contributions from the material microstructural evolution, by eliminating contributions from changes in geometry, to overall HTSMA spring performance. The finite element method (FEM) was used to support the analytical analyses and provided further insight into the behavior and heterogeneous stress states that exist in these spring actuators. Furthermore, with the goal of improving dimensional stability there is a need to better understand the microstructural evolution in HTSMAs that contributes to irrecoverable strains. Towards this goal, available Ni29.5Ti50.5Pd20 neutron diffraction data (from a comparable HTMSA alloy without the solid solution strengthening offered by the Pt addition) were analyzed. The data was obtained from in situ neutron diffraction experiments performed on Ni29.5Ti50.5Pd20 during compressive loading while heating/cooling, using the Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory. Specifically, in this work emphasis was placed on neutron diffraction data analysis via Rietveld refinement and capturing the texture evolution through inverse pole figures. Such analyses provided quantitative information on the evolution of lattice strain, phase volume fraction (including retained martensite that exists above the austenite finish temperature) and texture (martensite variant reorientation and detwinning) under temperature and stress. Financial support for this work from NASA's Fundamental Aeronautics Program Supersonics Project (NNX08AB51A), Subsonic Fixed Wing Program (NNX11AI57A) and the Florida Center for Advanced Aero-Propulsion (FCAAP) is gratefully acknowledged. It benefited additionally from the use of the Lujan Neutron Scattering Center at Los Alamos National Laboratory, which is funded by the Office of Basic Energy Sciences (Department of Energy) and is operated by Los Alamos National Security LLC under DOE Contract DE-AC52-06NA25396.ID: 030646204; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.A.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 102-106).
M.S.A.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering; Space System Design and Engineering Track
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Daverman, R. Dodge (Robert Dodge). "A novel binary actuator using shape memory alloy." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32363.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 95-96).
In situations that demand the use of the high-bandwidth, high-quality sense of vision for interactions with the physical world it would be beneficial to have a wearable tactile display that takes advantage of touch to communicate information to the user without causing visual distractions. This thesis presents the design and development of a novel actuator that can be configured into thin, flexible arrays to meet this need for wearable tactile displays. The actuator presented uses the strain recovery property of the martensitic transformation of Nitinol, a Shape Memory Alloy (SMA), to generate the actuation force. A compliant bistable mechanism provides the restoring force that pre- strains the martensitic Nitinol, and thus makes the actuator binary. Binary actuation alleviates some of the problems that would otherwise limit the effectiveness of Nitinol in wearable haptic systems. To increase the potential for commercial success, manufacturability issues are considered throughout the development cycle to ensure the potential for economical large scale production. The paper concludes with the presentation of three different prototypes. Their successes and failures are discussed along with recommendations for future work.
by R. Dodge Daverman.
S.M.
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Buban, Darrick Matthew. "Shape Memory Alloy Fracture as a Deployment Actuator." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/283604.
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Many applications require deployable structures to meet operational objectives such as satellites that unfurl antenna arrays. Typically, most deployment efforts involve the use of explosive and non-explosive actuators (EAs and NEAs respectively) that have implementation drawbacks such as the expense associated with special handling and the bulk encountered with mounting the devices. To mitigate EA and NEA drawbacks, the integration of shape memory alloys (SMA) as a deployment actuator was investigated. SMA specimens were heated and pulled to failure developing an environmental and structural operating envelope for application as deployment mechanisms. A Finite Element Model (FEM) was also created to model the response behavior induced during specimen testing so that modeled performance could be used in lieu of testing when integrating SMA actuators into deployment systems. Experimental results verified that SMAs can be implemented as deployment actuators. Recorded data showed that SMA fracture is possible over a wide range of temperatures and strains, filling a material performance gap not found in the literature. The obtained information allows design engineers to appropriately size SMAs given design requirements achieving the desired deployment effects. The Finite Element Model was partially successful, capable of emulating strained ambient material behavior up to approximately 6.1%. The limited response is due to lack of experimentally derived large stress and strain available for model emulation.
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Fox, Gordon. "Development of a characterization instrument for thermomechanical testing of shape memory alloy torque actuators." Connect to resource, 2010. http://hdl.handle.net/1811/45418.
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Lu, Xuemei. "A systems approach to modelling and design of high strain shape memory alloy actuators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37267.pdf.
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Lu, Xuemei 1970. "A systems approach to modelling and design of high strain shape memory alloy actuators /." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28000.
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A simulator is developed to model and design high strain shape memory alloy (SMA) tension actuators. The simulator may be used to predict characteristics of a given actuator, or to design its geometry under specifications such as force, speed, stroke and size. The accuracy of the model is verified experimentally in reference to an existing NiTi shape memory alloy prototype actuator. Having developed some confidence in the model, the performance of the proposed actuation mechanism is compared to other existing technologies. In particular, the force-displacement and speed characteristics of a micro-solenoid electro-magnetic actuator and a muscle-size pneumatic actuator are compared to those of the SMA actuators with same dimensions.A new concept of designing shape memory alloy bending actuator is presented in the end of the thesis. Part of the modelling work is accomplished in this research by developing a software simulator which is capable of predicting the geometric transformation of the actuator during bending. As a result, the dynamic strain of each SMA fiber in the actuator can be computed given a bending axis and angle. Graphical display of the bending transformation is implemented using in house software package. Further investigation of modelling and control of the SMA bending actuator is left as future work.
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Paine, Jeffrey S. "The performance of nitinol shape memory alloy actuators embedded in thermoplastic composite material systems." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/45109.
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Intelligent materials are a class of material systems usually consisting of a composite or hybrid material system with fibrous or distributed actuators, various sensors and a control system. One type of actuator being developed for intelligent material systems is made of nitinol or shape memory alloy wire. In order for nitinol and other actuators to be a reliable part of the system, the effect of composite manufacturing on the actuators’ performance and behavior must be determined. The results of a study investigating the effects of a "high temperature" thermoplastic composite processing cycle on the nitinol actuator’s performance is presented. A study of the interfacial strength between the actuators and APC-2 thermoplastic composite is also reported.
The nitinol actuators were exposed to high temperature (400°C) composite processing cycles. Critical parameters of the processing cycles were varied to determine their effect on the actuators’ performance. After the processing cycles, the nitinol actuators demonstrated useable recovery stresses (σru) of 173-265 MPa. The σru of a nitinol actuator in the virgin state, subjected to a thermoset processing cycle, and embedded in a specimen of APC-2 thermoplastic composite was also tested to develop a basis for comparison. The quality of the actuator-composite interface bond was tested by pull-out testing and fatigue loading to determine if the actuator is adequately bonded with the host composite. Pull-out forces of 30-50 N could fracture the actuator-composite interface, but 1000 activation cycles of the actuator produced no damage in the bond between actuator and host composite.Master of Science
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Toews, Leslie Marilyn. "The Development of a Monolithic Shape Memory Alloy Actuator." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/871.
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Shape memory alloys (SMAs) provide exciting opportunities for miniature actuation systems. As SMA actuators are scaled down in size, cooling increases and bandwidth, improves. However, the inclusion of a bias element with which to cycle the SMA actuator becomes difficult at very small scales. One technique used to avoid the necessity of having to include a separate bias element is the use of local annealing to fabricate a monolithic device out of nickel titanium (NiTi). The actuator geometry is machined out of a single piece of non-annealed NiTi. After locally annealing a portion of the complete device, that section exhibits the shape memory effect while the remainder acts as structural support and provides the bias force required for cycling. This work proposes one such locally-annealed monolithic SMA actuator for future incorporation in a device that navigates the digestive tract. After detailing the derivation of lumped electro-mechanical models for the actuator, a description of the prototyping procedure, including fabrication and local annealing of the actuator, is provided. This thesis presents the experimental prototype actuator behaviour and compares it with simulations generated using the developed models.
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Chun, Katherine S. (Katherine Shisuka). "Shape memory alloy rotary actuator for CubeSat deployable structures." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127066.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 77-82).
Small satellites have lowered the barrier to entry for space-bound science and technology demonstrations. However, the small form factor requires extremely low size, weight, and power for any on-board hardware. Precision actuation of deployable structures has previously been achievable only through low SWaP single-use actuators or motor-driven, high SWaP multiple-use actuators. The Folded Lightweight Actuated Positioning System has the potential to provide an ultra-lightweight multiple-use actuator by using a Joule-heated shape memory alloy-based hinge. The hinge uses two shape memory alloy strips which are trained in opposite directions and mounted into a rotary actuator. Two different shape memory alloy geometries are explored: a rectangular cross-section and a circular cross-section. The rectangular hinge actuates over a range of ±20° with an average power of 0.14 W. The circular hinge actuates over a range of ±23° with an average power of 0.073 W. A closed-loop controller uses pulse width modulation and encoder measurements to actuate the rectangular hinge to within 2' of the desired angle.
by Katherine S. Chun.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Souri, Mohammad. "FINITE ELEMENT MODELING AND FABRICATION OF AN SMA-SMP SHAPE MEMORY COMPOSITE ACTUATOR." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/38.
Full textAbstract:
Shape memory alloys and polymers have been extensively researched recently because of their unique ability to recover large deformations. Shape memory polymers (SMPs) are able to recover large deformations compared to shape memory alloys (SMAs), although SMAs have higher strength and are able to generate more stress during recovery.
This project focuses on procedure for fabrication and Finite Element Modeling (FEM) of a shape memory composite actuator. First, SMP was characterized to reveal its mechanical properties. Specifically, glass transition temperature, the effects of temperature and strain rate on compressive response and recovery properties of shape memory polymer were studied. Then, shape memory properties of a NiTi wire, including transformation temperatures and stress generation, were investigated. SMC actuator was fabricated by using epoxy based SMP and NiTi SMA wire. Experimental tests confirmed the reversible behavior of fabricated shape memory composites.
The Finite Element Method was used to model the shape memory composite by using a pre-written subroutine for SMA and defining the linear elastic and plastic properties of SMP. ABQUS software was used to simulate shape memory behavior. Beside the animated model in ABAQUS, constitutive models for SMA and SMP were also developed in MATLAB® by using the material properties obtained from experiments. The results of FEM simulation of SMC were found to be in good agreement with experimental results.
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Mohamed, Ali Mohamed Sultan. "Integration and wireless control methods for micromachined shape-memory-alloy actuators and their MEMS applications." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42820.
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Otieno, Timothy. "Shape memory Alloy Actuator for cross-feed in turning operation." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1012590.
Full textAbstract:
A shape memory alloy (SMA) is an intermetallic compound able to recover, in a continuous and reversible way, a predetermined shape during a thermal cycle while generating mechanical work. In this thesis, its use in developing an actuator for a machining process is investigated. The actuator is to drive the tool cross feed into an aluminium workpiece in a finishing lathe operation. The actuator structure was designed with an output shaft to transfer the movement and force of the SMA wire outside the device. The actuator was fabricated and the experimental setup was assembled which also included a power supply control circuit, displacement sensor, temperature sensor and current sensor for feedback, and data collection and monitoring within software. PID control was implemented within the software that regulated the power supplied to the SMA, thereby providing the position control. This study covers the mechatronics system design and development of the actuator, the experiments carried out to determine performance and the results. Open loop tests were conducted to determine the maximum stroke, the effect of cooling and response to radial forces. These tests revealed the expected non-linearity of the SMA. The actuator achieved the rated maximum stroke of 3-4 percent. The forced cooling test showed a general improvement of approximately 65 percent with fans. The radial force tests showed the value of the maximum stroke remained unaffected by force. The results from the closed loop tests responses with a tuned PID controller produced a stable system for various displacement setpoints. The actuator had a feed rate of 0.25 mm/s and an accuracy of 0.0153mm, which was within the acceptable accuracy for turning operations. The system was deemed accurate for a conventional lathe machine cross feed.
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Soylemez, Burcu. "Design And Analysis Of A Linear Shape Memory Alloy Actuator." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610340/index.pdf.
Full textAbstract:
Shape memory alloys are new, functional materials used in actuator applications with their high power to weight ratio. The high strength or displacement usage of shape memory alloys makes them suitable for direct drive applications, which eliminate use of power transmission elements.
The aim of this research is to develop the methodology and the necessary tools to design and produce linear shape memory alloy actuators to be used in missile systems, space applications, and test equipments.
In this study, the test apparatus designed and built to characterize shape memory alloy thin wires is described, and then the characterization tests, modeling and control studies performed on a wire are explained. In the control studies, displacement control through strain, resistance and power feedback is investigated and different control strategies (proportional-integral, proportional-integral with feedforward loop, and neural network) are employed. The results of the characterization tests, simulations and experiments are all presented in graphical and tabular form. From the results it is concluded that through careful characterization, the behavior of SMA wire can be closely approximated through models which can be used effectively to test various control strategies in simulations. Also, satisfactory position control of SMA wires can be achieved through both classical and NN control strategies by using appropriate feedback variables and power is found to be a viable feedback variable.
Lastly, a linear SMA wire actuator is designed as a case study. The actuator prototype is produced, suitable control strategies are applied and actuator is experimented to validate the theoretical assumptions.
The actuator developed through this work is a technology demonstration and shows that shape memory alloy elements can be utilized in several defense and space applications contracted to TÜBiTAK-SAGE as well as certification test equipments. The development of shape memory alloy actuators that can be used in defense and later in aeronautical/space applications is a critical research and development project for national defense industry.
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Khatsenko, Maxim O. "A rotary shape memory alloy actuator for CubeSat deployable structures." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111751.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 155-158).
Over a decade of continuing CubeSat technology improvements are driving the wide adoption of CubeSats for research and commercial missions. Resource constraints onboard CubeSats still limit their ability to support multi-use actuators, but there is a need for a rotary CubeSat actuator that can be actively commanded to different angles. This type of actuator can be implemented in a CubeSat mechanism for differential drag management, increased power generation, and reconfigurable deployable structures. We propose using a shape memory alloy (SMA) actuator to meet this need. A SMA can be annealed at high temperatures to remember a trained shape. Upon cool down, the SMA element transforms to the martensite phase and is easily deformed. When the element is heated above the transformation temperature it transforms to the stiff austenite phase and assumes its remembered shape, driving the mechanism. Two SMA actuators are trained to different shapes and provide bidirectional rotary motion for use as a space mechanism. The actuators are designed by implementing kinematic, thermal, and bending models to size the SMA element. The models also predict the performance, size, weight, and power of the actuator and ensure it can operate in the CubeSat environment. Then, a prototype of the proposed actuator is manufactured, assembled, and ground tested. Testing is used to validate the models and verify the requirements necessary to operate onboard a CubeSat. The prototype meets all requirements and offers a reduced mass, volume, and complexity alternative to current CubeSat electromagnetic actuators. Future work is necessary to improve the mechanical performance and positional control of the SMA actuator.
by Maxim O. Khatsenko.
S.M.
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Hegana, Ashenafi B. "Low Temperature Waste Energy Harvesting by Shape Memory Alloy Actuator." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461631046.
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Huang, Weimin. "Shape memory alloys and their application to actuators for deployable structures." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299009.
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Han, L. "Shape memory alloys : numerical simulation and optimal design of SMA actuators." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603638.
Full textAbstract:
Shape memory alloys (SMAs) are particularly attractive as actuators in smart structures, due to their large actuation strain/stress, high power/weight ratio, single actuation mechanism and low noise etc. However, the lack of reliable predictive models and computational and design tools severely limits their applications. This thesis is concerned with the models appropriate for the numerical implementation, and the optimal design procedure of SMA actuators. To understand the thermomechanical characteristics of NiTi SMAs, a number of tests have been carried out, including iso-thermal tension tests under different constant temperatures, iso-thermal tension tests with different constant strain rates, iso-stress thermal cycling tests under different constant stresses, repeated iso-stress thermal cycling tests and repeated iso-thermal superelastic mechanical cycling tests. The stress-temperature phase diagrams for phase transformations are constructed. Under the framework of generalized plasticity with an internal-variable formalism, a three-dimensional phenomenological model is developed. Based on the stress-temperature phase diagram, the evolution equations of phase fractions are derived. The model reproduces the basic features of SMAs, such as the shape memory effect (SME) and superelasticity (SE), and can deal with incomplete phase transformations. Using return mapping algorithms, the incremental numerical formulation of the model is implemented into ABAQUS, through a user-defined material subroutine. Numerical examples and comparisons between the simulations and experiments have shown the capacity of the model and the feasibility of the subroutine. The design method of a typical bias SMA actuation unit is developed. The relationship of the actuation stress, strain and temperature is obtained by solving a coupled problem combining a thermomechanical constitutive model, heat conduction equations and the spring response. A novel lightweight SMA actuator integrating SMA actuation units into a truss structure is proposed, optimised and manufactured to demonstrate the possibility of SMA actuators in the application of smart structures.
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Williams, Eric Andrew. "The Development of Actuators for the Whole Skin Locomotion Robot." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/46786.
Full textAbstract:
The Whole Skin Locomotion robot propels itself using a motion similar to the cytoplasmic streaming exhibited by an amoeba. In the robot there are embedded ring actuators which evert the material of the robot to produce forward motion. The robot benefits from a highly flexible exterior allowing it to squeeze into constricted passageways or collapsed structures. The development of actuators for such a motion is performed by a shape memory alloy composite actuator. Unlike a typical composite model which utilizes a homogenization of fiber and matrix properties our model is developed for line loads produced in individual shape memory alloy wires onto the rod structure. The load vectors are determined in the deformed configuration of the actuator to account for the highly deformed actuator profiles that would be seen in operation. Also the load requirements for such actuators are developed in terms of the constriction forces and functional design limits are established. In addition, a helical spring backbone design is considered and stiffness properties for general helical springs are determined. The contact of spring coils is included in the analysis and a coupled constitutive model is developed for the spring when coils are in contact. The static design of helical springs for use in the actuators is performed and deformation and load restrictions are determined for subsequent design efforts.Ph. D.
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Lenahan, Kristie M. "Thermoelastic control of adaptive composites for aerospace applications using embedded nitinol actuators." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/44955.
Full textAbstract:
Aerospace structures have stringent pointing and shape control requirements during long-term exposure to a hostile environment with no scheduled maintenance. This makes them excellent candidates for a smart structures approach as current passive techniques prove insufficient. This study investigates the feasibility of providing autonomous dimensional control to aerospace structures by embedding shape memory alloy elements inside composite structures. Increasing volume fractions of nitinol wire were embedded in cross-ply graphite/ epoxy composite panels. The potential of this approach was evaluated by measuring the change in longitudinal strain with increasing temperature and volume fraction. Reduction of thermal expansion is demonstrated and related to embedded volume fraction.
Classical lamination theory is used to formulate a two-dimensional model which
included the adaptive properties of the embedded nitinol. The model was used to predict
the increased modulus and reduction of thermal strain in the modified plates which was
verified by the experimental data.
Master of Science
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Kianzad, Soheil. "A treatise on highly twisted artificial muscle : thermally driven shape memory alloy yarn and coiled nylon actuators." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54782.
Full textAbstract:
A new perspective in the field of actuators was opened by the demonstration of multiwall carbon nanotube based actuators by Foroughi et al, in 2011. The approach involves applying a high degree of twist to create large torsional actuation in carbon nanotube yarns, and more recently in coiled nylon filaments. In this thesis torsional actuation is further studied in nylon, and extended to shape memory alloys (SMA).
Torsional actuation is demonstrated using 25 μm diameter micro strands of shape memory alloy (SMAs) that are twisted together. These form yarns with Young’s modulus of 13.5 GPa in the Martensitic phase and 18 GPa in the Austenite state. In torsion, the SMA yarns show more than 8,000 rpm peak rotational speed with 11 reversible rotations for an 8 cm long yarn. This is observed upon applying 0.47 W/cm electrical input power. Providing more than 5 N.m/kg torque, SMA yarns may be of interest in biomedical and other applications. The mechanical behaviour of coiled nylon actuators is studied by testing elastic modulus and by investigating tensile stroke as a function of temperature. Loads that range from 35 MPa to 155 MPa were applied. For the nylon and the coiling conditions used, active thermal contraction totals 19.5 % when the temperature is raised from -40 ⁰C to 160 ⁰C, with most contraction above the glass transition temperature. Introducing various cooling methods was shown to enable increased rate of actuation up to several Hertz. Nylon coiled actuators potentially provide affordable and viable solutions for driving mechanical devices as recently demonstrated in robotic hands and arms. A new biomimetic arrangement of the nylon actuator is presented that imitates the human pennate muscle in structure, including the ability to vary stiffness by a factor of 9 and to increase isometric force from 19 N to 37 N by recruiting additional fibers.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Krishnan, Vinu Bala. "Low temperature NiTiFe shape memory alloys actuator engineering and investigation of deformation mechanisms using in situ neutron diffraction at Los Alamos National Laboratory /." Orlando, Fla. : University of Central Florida, 2007. http://purl.fcla.edu/fcla/etd/CFE0001934.
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Ho, Eric. "Linear Macro-Micro Positioning System Using a Shape Memory Alloy Actuator." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/816.
Full textAbstract:
The use of high-precision automated equipment is steadily increasing due in part to the progressively smaller sizes of electronic circuits. Currently, piezoelectric transducers (piezos) dominate as the actuation device for high precision machines, but shape memory alloys (SMA) may be a viable alternative to reduce monetary costs. This work explores the implementation of a low-cost linear macro-micro positioning system. The system consists of a modified printer carriage to provide long range, macro scale linear motion (approximately 200 mm range and 200 µm precision) and a micro scale system (approximately 4 mm range and 5 µm target precision) that uses an SMA actuator. A detailed description of the design and implementation of the system is given in this research. A model of the macro-stage is then generated by first identifying and inverting a simple friction model to linearize the system, thereby allowing for modified least squares (MLS) identification of a linear model. Various controllers are attempted for the macro-stage and compared with an experimentally tuned nonlinear PD controller that is implemented in the final design. A model of the micro-stage is derived through analysis of the SMA actuator. The model for the actuator is separated into two portions, an electro-thermal model, and a hysteresis model. The hysteresis model is derived using the Preisach model, and the electro-thermal model through MLS identification. To control the micro-stage, a PI controller with antiwindup is developed experimentally. The two stages are then executed together in closed loop and the resulting coupling between the two stages is briefly examined. Experimental data used for the modelling and design is presented, along with results of the final macro-micro linear positioning system.
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Grant, Danny. "Shape memory alloy actuator with an application to a robotic eye." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22650.
Full textAbstract:
A novel Shape Memory Alloy (SMA) actuator is presented. The SMA actuator consists of twelve thin NiTi fibers woven in a counter rotating helical pattern around supporting disks. Fibers woven in this pattern accomplish a high efficiency transformation between force and displacement. In this manner, the actuator overcomes the two main mechanical drawbacks of shape memory alloys, that being limited strain and limited cycle lifetime. Experimental results with two actuators operating in an antagonistic manner demonstrate the feasibility of the actuators for use in miniature robotic systems.Further, a camera platform was constructed as an application for the actuators. The camera platform prototype orients a small CCD camera head, that supplies data to a foveated vision system. The three degrees of freedom pan, tilt, and torsion, are realized by four actuators in an antagonistic fashion. The camera support was manufactured using light weight plastic, including the use of plastic hinges to reduce the use of weighty bearings.
Control of the actuators is accomplished via a two stage switching feedback law that has its basis in sliding mode control theory. Essentially, the controller switches according to the sign of the error choosing which actuator is agonist and which is the antagonist.
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Avirovik, Dragan. "System Level Approach towards Intelligent Healthcare Environment." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/49581.
Full textAbstract:
Surgical procedures conducted without proper guidance and dynamic feedback mechanism could lead to unintended consequences. In-vivo diagnostics and imaging (the Gastro-Intestinal tract) has shown to be inconvenient for the patients using traditional endoscopic instruments and often these conventional methods are limited in terms of their access to various organs (e.g. small intestines). Embedding sensors inside the living body is complex and further the communication with the implanted sensors is challenging using the current RF technology. Additionally, continuous replacement and/or batteries recharging for wireless sensors networks both in-vivo and ex-vivo adds towards the complexity. Advances in diagnostics and prognostics techniques require development at multiple levels through systems approach, guided by the futuristic intelligent decision making environment that reduces the human interference. The demands are not only at the component level, but also at the connectivity of the components such that secure, sustainable, self-reliant, and intelligent environment can be realized. This thesis provides important breakthroughs required to achieve the vision of intelligent healthcare environment. The research contributions of this thesis provide foundation for developing a new architecture for continuous medical diagnostic and monitoring. The chapters in this thesis cover four fundamental technologies covering the in-vivo imaging, ex-vivo imaging, energy for sensors, and acoustic communication. These technologies are: locomotion mechanism for wireless capsule endoscope (WCE), multifunctional image guided surgical (MIGS) platform, shape memory alloy (SMA) thermal energy harvester and thermo-acoustic sonar using carbon nanotube (CNT) sheets.
First, two types of locomotion mechanisms were developed, the first one inspired by millipede legged type mechanism and the second one based on the traveling waves that were induced onto the walls of the WCEs through vibration. Both mechanisms utilize piezoelectric actuators and couple their dynamics and actuation capability in order to achieve propulsion. This controlled locomotion will provide WCE advantage in terms of conducting localized diagnostics. Next, in order to conduct ex-vivo surgical procedures using the OCT such as removing the unwanted tissue and tumors short distance beneath the skin, MIGS platform was developed. The MIGS platform is composed of three key elements: optical coherence tomography (OCT) probe, laser scalpel and high precision miniature scanning and positioning stage. The focus in this dissertation was on design and development of the programmable scanning and positioning stage. The combination of in-vivo tool such as WCE and ex-vivo tool such as MIGS will provide opportunity to conduct many non-invasive procedures which will save time and cost. In order to power the feedback sensors that assist in remote operation of surgical procedures and automation of the diagnostic algorithms, an energy harvester technology based on the SMA thermal engine was designed, fabricated, and characterized. A mechano-thermal model for the overall SMA engine was developed and experimentally validated. Finally, the thermo-acoustic sound generation mechanism using CNT sheets was investigated with the goal of developing techniques for acoustic localization of WCE and customized sound generation devices. CNT thermo-acoustic projectors were modeled and experimentally characterized to quantify the dynamics of the system under varying drive conditions.
The overall vision of this thesis is to lay down the foundation for intelligent healthcare environment that provides the ability to conduct automated diagnostics, prognostics, and non-invasive surgical procedures. In accomplishing this vision, the thesis has addressed several key fundamental aspects of various technologies that will be required for implementing the automation algorithms.Ph. D.
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Motzki, Paul [Verfasser], and Stefan [Akademischer Betreuer] Seelecke. "Advanced design and control concepts for actuators based on shape memory alloy wires / Paul Motzki ; Betreuer: Stefan Seelecke." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2018. http://d-nb.info/1169132502/34.
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Motzki, Paul Verfasser], and Stefan [Akademischer Betreuer] [Seelecke. "Advanced design and control concepts for actuators based on shape memory alloy wires / Paul Motzki ; Betreuer: Stefan Seelecke." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2018. http://d-nb.info/1169132502/34.
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Narayanan, Pavanesh. "Sensor-less Control of Shape Memory Alloy Using Artificial Neural Network and Variable Structure Controller." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1416501021.
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Saal, Sheldon C. "The development of an active surface using shape memory alloys." Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/1292.
Full textAbstract:
This thesis work was conducted in the Department of Mechanical Engineering
at the Cape Peninsula University of Technology (CPUT) and was submitted
towards the partial fulfilment of the Masters Degree in Technology:
Mechanical Engineering.Recent years have witnessed a tremendous growth and significant advances in “smart” composites and “smart” composite structures. These smart composites integrate active elements such as sensors and actuators into a host structure to create improved or new functionalities through a clever choice of the active elements and/or a proper design of the structure. Such composites are able to sense a change in the environment and make a useful response by using an external feedback control system. Depending on their applications, smart composites usually make use of either the joint properties of the structure or the properties of the individual elements within the composites. The accumulation in the understanding of materials science and the rapid developments in computational capabilities have provided an even wider framework for the implementation of multi-functionality in composites and make “smart” composites “intelligent”.
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Jun, Hyoung Yoll. "Development of a fuel-powered compact SMA (Shape Memory Alloy) actuator system." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1426.
Full textAbstract:
The work presents investigations into the development of a fuel-powered compact SMA actuator system. For the final SMA actuator, the K-alloy SMA strip (0.9 mm x 2.5 mm), actuated by a forced convection heat transfer mechanism, was embedded in a rectangular channel. In this channel, a rectangular piston, with a slot to accommodate the SMA strip, ran along the strip and was utilized to prevent mixing between the hot and the cold fluid in order to increase the energy density of the system. The fuel, such as propane, was utilized as main energy source in order to achieve high energy and power densities of the SMA actuator system. Numerical analysis was carried out to determine optimal channel geometry and to estimate maximum available force, strain and actuation frequency. Multi-channel combustor/heat exchanger and micro-tube heat exchanger were designed and tested to achieve high heat transfer rate and high compactness. The final SMA actuator system was composed of pumps, valves, bellows, multi-channel combustor/heat exchanger, micro-tube heat exchanger and control unit. The experimental tests of the final system resulted in 250 N force with 2 mm displacement and 1.0 Hz actuation frequency in closed-loop operation, in which the hot and the cold fluid were re-circulated by pumps.