Download or read book Characterization and Modeling of Ferromagnetic Shape Memory NiMnGa Actuators written by Xiang Wang and published by . This book was released on 2008 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: It has been shown that a magnetic field induced strain (MFIS) up to 10% can be obtained when Ferromagnetic Shape Memory Alloys (FSMAs) in the NiMnGa system are driven by perpendicular magnetic field and mechanical stresses. Prior experiments on single crystal NiMnGa have demonstrated the existence of reversible strains along the [001] crystallographic axis of a cylindrical rod under the application of collinear magnetic fields and stresses. This unusual behavior is used in this paper to develop a dynamic model for NiMnGa as operated in a solenoid transducer consisting of a driving coil and an external mass-spring-damper loading. A constitutive model to describe the motion of twin boundaries in the presence of energetically strong pinning sites is presented. The effective pinning strength is represented by an internal bias stress oriented transversely. This also explains the reduced maximum MFIS of -0.41% compared to possible -6% obtained from its variant structure. Stochastic homogenization is then used to account for variability in the bias stresses throughout the material and inhomogeneity in the interaction field intensity. Finally, the internal rod dynamics are modeled through force balancing with boundary conditions dictated by the constructive details of the transducer and mechanical load. The model is formulated in variational form, resulting in a second-order temporal system with magnetic field induced strain as the driving mechanism. Model results are compared with experimental measurements for validation and parameter identification. To provide a theoretical understanding of the frequency-dependent power losses in NiMnGa, this dissertation also extends the constitutive hysteresis model by incorporating eddy current and magnetic domain configuration(anomalous) losses; the analytical solutions are compared with finite element simulations. Finally, a parametric analysis of NiMnGa actuator performance based on energy delivery efficiency and the energy conversion efficiency is provided. The optimal stiffness ratios from the classical linear constitutive model and our nonlinear model are experimentally validated. The approach presented is useful for designing a control system, especially for the purpose of designing an energy efficient control system.

Download or read book Shape Memory Alloy Actuators written by Mohammad H. Elahinia and published by John Wiley & Sons. This book was released on 2016-01-19 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a systematic approach to realizing NiTi shape memory alloy actuation, and is aimed at science and engineering students who would like to develop a better understanding of the behaviors of SMAs, and learn to design, simulate, control, and fabricate these actuators in a systematic approach. Several innovative biomedical applications of SMAs are discussed. These include orthopedic, rehabilitation, assistive, cardiovascular, and surgery devices and tools. To this end unique actuation mechanisms are discussed. These include antagonistic bi-stable shape memory-superelastic actuation, shape memory spring actuation, and multi axial tension-torsion actuation. These actuation mechanisms open new possibilities for creating adaptive structures and biomedical devices by using SMAs.

Download or read book Modeling and Control of Ferromagnetic Shape Memory Alloy Actuators written by Honghao Tan and published by . This book was released on 2006 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ferromagnetic Shape Memory Alloy materials such as Ni-Mn-Ga have attracted significant attention over the last few years. As actuators, these materials offer high bandwidth, large stroke, and high displacement resolutions. In this dissertation, the main interests are to model the constitutive behavior of Ni-Mn-Ga under simultaneously changing fields and stress and design new actuator based on Ni-Mn-Ga.

Download or read book Design and Characterization of Acoustic Pulse Shape Memory Alloy Actuators written by Joshua Michael Chambers and published by . This book was released on 2005 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermomechanical Training and Characterization of Shape Memory Alloy Axial Actuators written by Marcus Patrick Becker and published by . This book was released on 2010 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Smart Structures and Materials written by and published by . This book was released on 2006 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling and Analysis of One and Two Dimensional Shape Memory Alloy elastomer Actuators written by Weida Wu and published by . This book was released on 1996 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis and Control of Magnetic Shape Memory Actuators written by 林致宏 and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Structural Integrity written by Krishna Jonnalagadda and published by Springer Nature. This book was released on 2022-03-11 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises the proceedings of the 3rd Structural Integrity Conference and Exhibition (SICE 2020). The contents of the volume focus on structural integrity, life prediction, and condition monitoring which are reclassified under the domains of aerospace, fracture mechanics, fatigue, creep-fatigue interactions, civil structures, experimental techniques, computation mechanics, structural health monitoring, nondestructive testing, failure analysis, materials processing, stress corrosion cracking, reliability and risk analysis. This book will be a useful reference for students, researchers and practitioners.

Download or read book Shape Memory Alloys written by Dimitris C. Lagoudas and published by Springer Science & Business Media. This book was released on 2008-06-05 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a working knowledge of the modeling and engineering applications of shape memory alloys (SMAs), beginning with a rigorous introduction to continuum mechanics and continuum thermodynamics as they relate to the development of SMA modeling.Modern SMAs can recover from large amounts of bending and deformation, and millions of repetitions within recoverable ranges. SMAs are used in the medical industry to create stents, in the dental industry to create dental and orthodontic archwires, and in the aerospace industry to create fluid fittings. The text presents a unified approach to the constitutive modeling of SMAs, including modeling of magnetic and high temperature SMAs.

Download or read book Mechanical Sensing Based on the Ferromagnetic Shape Memory Alloy NiMnGa written by Jochen Stephan and published by . This book was released on 2015 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the ASME Aerospace Division written by American Society of Mechanical Engineers. Aerospace Division and published by . This book was released on 2005 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Shape Memory Alloy Actuators written by Burcu Dönmez and published by . This book was released on 2011-11 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Fundamental Characterization of Shape Memory Alloy Actuators for Use in Hand Protheses written by Mark Anthony Thrasher and published by . This book was released on 1991 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling and Analysis of Shape Memory Alloy Actuators for Robotic and Orthotic Applications written by John Edward Makaran and published by . This book was released on 1990 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetic Shape Memory Alloys written by Xuexi Zhang and published by Springer Nature. This book was released on 2021-11-14 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book systematically describes the fundamentals of Magnetic shape memory alloys (MSMAs), with an emphasis on low-dimensional structures such as foams, microwires and micro-particles. The respective chapters address basic concepts and theories, the fabrication of various architectures, microstructure tailoring, property optimization and cutting-edge applications. Taken together, they provide a clear understanding of the correlation between processing and the microstructural properties of MSMAs, which are illustrated in over two hundred figures and schematics. Given its scope and format, the book offers a valuable resource for a broad readership in various fields of materials science and engineering, especially for researchers, students and engineers.