Modeling of Shape Memory Alloy (SMA) Spring Elements for Passive Vibration Isolation Using Simplified SMA Model and Preisach Model PDF Download
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Author: Mughees Mahmood Khan
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
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Author: Mughees Mahmood Khan
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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In this work, the effect of pseudoelastic response of shape memory alloys (SMAs) on passive vibration isolation has been investigated. This study has been conducted by developing, modeling, and experimentally validating a SMA-based vibration isolation device. This device consists of layers of preconstrained SMA tubes undergoing pseudoelastic transformations under transverse dynamic loading. These SMA tubes are referred to as SMA spring elements in this study. To accurately model the nonlinear hysteretic response of SMA tubes present in this device, at first a Preisach model (an empirical model based on system identification) has been adapted to represent the structural response of a single SMA tube. The modified Preisach model has then been utilized to model the SMA-based vibration isolation device. Since this device also represents a nonlinear hysteretic dynamical system, a physically based simplified SMA model suitable for performing extensive parametric studies on such dynamical systems has also been developed. Both the simplified SMA model and the Preisach model have been used to perform experimental correlations with the results obtained from actual testing of the device. Based on the studies conducted, it has been shown that SMA-based vibration isolation devices can overcome performance trade-offs inherent in typical softening spring-damper vibration isolation systems. This work is presented as a two-part paper. Part I of this study presents the modification of the Preisach model for representing SMA pseudoelastic tube response together with the implemented identification methodology. Part I also presents the development of a physically based simplified SMA model followed by model comparisons with the actual tube response. Part II covers extensive parametric study of a pseudoelastic SMA spring-mass system using both models developed in Part I.
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Category :
Languages : en
Pages : 0
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In Part II of this two-part study, system simulations and experimental correlations of a Shape Memory Alloy (SMA) based vibration isolation device (briefly described in Part I) has been presented. This device consists of layers of pre-constrained SMA tubes undergoing pseudoelastic transformations under transverse dynamical loading. In Part II, detailed description of the prototype vibration isolation device, its experimental setup, and actual experimental test results are presented. An extensive parametric study has been conducted on a nonlinear hysteretic dynamical system, representing this vibration isolation device utilizing a physically based simplified SMA model and a Preisach model (an empirical model based on system identification) developed in Part I. Both the physically based simplified SMA model and the modified Preisach model have been utilized to perform experimental correlations with the results obtained from actual testing of the device. Based on the investigations, it has been shown that variable damping and tunable isolation response are major benefits of SMA pseudoelasticity. Correlation of numerical simulations and experimental results has shown that large amplitude displacements causing phase transformations of SMA components present in such a device are necessary for effective reduction in the transmissibility of such dynamical systems. It has also been shown that SMA-based devices can overcome performance tradeoffs inherent in typical softening spring-damper vibration isolation systems. In terms of numerically predicting the experimental results, it has been shown that the Preisach model gave relatively accurate results due to better modeling of the actual SMA tube behavior. However for a generic parametric study, the physically based simplified SMA model has been found to be more useful as it is motivated from the constitutive response of SMAs and hence, could easily incorporate different changes in system conditions.
Author:
Publisher:
ISBN:
Category : Smart materials
Languages : en
Pages : 434
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Author: Luciano G Machado
Publisher:
ISBN:
Category :
Languages : en
Pages :
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This work investigates the use of shape memory alloys (SMAs) for vibration isolation and damping of mechanical systems. The first part of this work evaluates the nonlinear dynamics of a passive vibration isolation and damping (PVID) device through numerical simulations and experimental correlations. The device, a mass connected to a frame through two SMA wires, is subjected to a series of continuous acceleration functions in the form of a sine sweep. Frequency responses and transmissibility of the device as well as temperature variations of the SMA wires are analyzed for the case where the SMA wires are pre-strained at 4.0% of their original length. Numerical simulations of a one-degree of freedom (1-DOF) SMA oscillator are also conducted to corroborate the experimental results. The configuration of the SMA oscillator is based on the PVID device. A modified version of the constitutive model proposed by Boyd and Lagoudas, which considers the thermomechanical coupling, is used to predict the behavior of the SMA elements of the oscillator. The second part of this work numerically investigates chaotic responses of a 1- DOF SMA oscillator composed of a mass and a SMA element. The restitution force of the oscillator is provided by an SMA element described by a rate-independent, hysteretic, thermomechanical constitutive model. This model, which is a new version of the model presented in the first part of this work, allows smooth transitions between the austenitic and the martensitic phases. Chaotic responses of the SMA oscillator are evaluated through the estimation of the Lyapunov exponents. The Lyapunov exponent estimation of the SMA system is done by adapting the algorithm by Wolf and co-workers. The main issue of using this algorithm for nonlinear, rateindependent, hysteretic systems is related to the procedure of linearization of the equations of motion. The present work establishes a procedure of linearization that allows the use of the classical algorithm. Two different modeling cases are considered for isothermal and non-isothermal heat transfer conditions. The evaluation of the Lyapunov exponents shows that the proposed procedure is capable of quantifying chaos in rate-independent, hysteretic dynamical systems.
Author:
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Category : Signal processing
Languages : en
Pages : 606
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Author:
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ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 412
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"Education, arts and social sciences, natural and technical sciences in the United States and Canada".
Author: Ashwin Rao
Publisher: Springer
ISBN: 3319031880
Category : Science
Languages : en
Pages : 137
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Book Description
This short monograph presents an analysis and design methodology for shape memory alloy (SMA) components such as wires, beams, and springs for different applications. The solid-solid, diffusionless phase transformations in thermally responsive SMA allows them to demonstrate unique characteristics like superelasticity and shape memory effects. The combined sensing and actuating capabilities of such materials allows them to provide a system level response by combining multiple functions in a single material system. In SMA, the combined mechanical and thermal loading effects influence the functionality of such materials. The aim of this book is to make the analysis of these materials accessible to designers by developing a "strength of materials" approach to the analysis and design of such SMA components inspired from their various applications with a review of various factors influencing the design process for such materials.
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ISBN:
Category :
Languages : en
Pages : 23
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Book Description
Through a mathematical and computational model of the physical behavior of shape memory alloy wires, this study shows that localized heating and cooling of such materials provides an effective means of damping vibrational energy. The thermally induced pseudo-elastic behavior of a shape memory wire is modeled using a continuum thermodynamic model and solved computationally as described by the authors in [23]. Computational experiments confirm that up to 80% of an initial shock of vibrational energy can be eliminated at the onset of a thermally-induced phase transformation through the use of spatially-distributed transformation regions along the length of a shape memory alloy wire.
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Category :
Languages : en
Pages :
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Book Description
Shape memory alloys (SMA) belong to the class of active materials and have recently been considered as novel actuation and damping mechanisms in micro- and macro-scale applications. Combined with their advantageous lightweight and high work output characteristics is a complex, highly non-linear and hysteretic material behavior, which is also thermo-mechanically coupled. Due to this complexity, model development for SMA material behavior is a challenging task, and experimental data in particular about the inner hysteresis loops is necessary to gain further understanding and successfully design applications. In this thesis, a single crystal material model is presented and subsequently extended to the more realistic polycrystalline case considering material inhomogeneities, grain impurities and lattice imperfections. A first implementation, based on a stochastic homogenization procedure, provides a very accurate description of the observed phenomena, but also requires very high computation times. A reformulation of the underlying concept leads to a parameterization method, which preserves the advantages of the original method, but dramatically reduces the computation times. It is shown that the material behavior prediction of both models are identical, and the parameterization method is compared extensively to data from tensile experiments with a pseudoelastic SMA wire. Remarkably, the model is able to capture all facets of the material behavior including rate-dependence and minor loops. The versatility of the model also allows for the simulation of SMA actuator behavior including the electrical resistance. Finally, a MEMS device using polycrystalline SMA thin film actuators is experimentally investigated. As a first step, the material behavior of the SMA thin films is presented using strain-temperature and resistance-temperature measurements. Secondly, the performance of the MEMS device was determined for different driving frequencies.
