Mathematical Modelling of Shape Memory Alloy Effect (original) (raw)
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Experimental Bench for Shape Memory Alloys Actuators Design and Testing
Shape memory alloys (SMAs) are used as active elements in novel actuation devices. Two generic types of SMA actuators can be distinguished according to the type of bias passive-bias actuators where an elastic component serves as a bias and active-bias actuators where two SMA elements are connected together. This paper describes an experimental testing bench developed for the characterization of SMA active elements and their testing in a real actuation environment. The characterization of SMA active elements is performed under three complementary testing modes: (a) constant-stress, (b) fixed-support, and (c) elasticbias recovery modes. Force, displacement and temperature data acquired during testing of a given SMA active element are then used to assess the mechanical work-generation potential of this active element and, ultimately, for the design of an SMA actuator containing this element. Finally, a case study is presented to illustrate the experimental design methodology and results.
Modeling and design of shape memory alloy actuators
2005
Thls paper presents the application of systematic model-based design techniques to the design of Shape Memory Alloy (SMA) actuators. Shape memory alloys are promising materials for (micro-)actuation, because of the relatively large deformations and forces that can be achieved. However, the complex ctmstitutive behavior and the fact that several physical domains (electrical, thermal and mechanical) play a role makes it difficult to design effective SMA actuators with complex shapes and layouts.
Contribution to Shape Memory Alloys Actuated Systems Design
Analele Universităţii "Eftimie Murgu" Reşiţa: Fascicola I, Inginerie, 2009
Even it has been recognized that Shape Memory Alloys have a significant potential for deployment actuators, the number of applications of SMA-based actuators to the present day is still quite small, due to the need of deep understanding of the thermomechanical behavior of SMA. SMAs offer attractive potentials such as: reversible strains of several percent, generation of high recovery stresses and high power / weight ratios. This paper tries to provide an overview of the shape memory functions. A table with property values for different properties of shape memory alloys is also included
Shape Memory Alloy Actuators: A Review
International Journal for Research in Applied Science and Engineering Technology
The Shape memory alloys (SMAs) comes under special class of materials which possesses ability to recover their original shape at some temperatures characteristics. The SMAs are being used in different field in variety of applications. This ability of SMA can be viewed under high applied loads and elastic deformations. In this review paper, the SMA actuators and their applications are discussed. Keywords: SMA, Types of SMA, actuator. I. INTRODUCTION The term ''smart alloy'' was introduced in 1932 and the nomenclature ''shape-memory'' was given in 1941 for polymeric dental material [1, 2, 3]. Shape memory alloys (SMAs) are a unique type of material contains the ability to recover their shape at certain temperature characteristics. These materials are able to regain their original shape, even after reaching large inelastic deformations (near 10%) [1]. The demand for SMAs for engineering applications has been increasing in different fields; such as in industrial applications, automobile industries, aerospace applications, structures and composites, robotics and biomedical applications [4, 5]. Different SMA actuators like wire, compression / tension springs and cantilever had been used in thermal and electrical actuation systems [7, 33]. In this paper, a review on different applications of SMA actuators is presented.
Computational Materials Science, 2000
This paper analyzes and compares the predictions of two sharp phase-front based shape memory alloy (SMA) constitutive models – proposed by Abeyaratne and Knowles (R. Abeyaratne, J. Knowles, Journal of Mechanics and Physics of Solids 41 (1993) 541) and Bruno et al. (O. Bruno, P. Leo, F. Reitich, Phys. Rev. Lett. 74 (1995) 746–749) – in the context of an SMA linear actuator (an SMA rod or a wire) actuated electrically and subjected to spring-loaded boundary conditions at its ends. Both models are then used to analyze the performance – i.e., specific energy output and energy efficiency – of the SMA actuator. The computational modeling is done using a moving boundary finite element method (MBFEM)-based numerical approach proposed by Stoilov et al. (V. Stoilov, O. Iliev, A. Bhattacharyya, Computer Methods in Applied Mechanics and Engineering, accepted). It is seen that while both models produce somewhat differing predictions of the SMA response, the difference is not dramatic enough to prefer one model to another. Predictions of the SMA actuator performance indicate that there is an optimum spring stiffness at which the energy efficiency of the SMA actuator is at its maximum. This raises the possibility that when an SMA actuator is integrated into a structure, the passive components of the structure may play a key role in determining the optimum energy efficiency of the active structural component (the SMA actuator) during the activation of the structure.
Characterization and design of antagonistic shape memory alloy actuators
Antagonistic shape memory actuators use opposing shape memory alloy (SMA) elements to create devices capable of producing differential motion paths and two-way mechanical work in a very efficient manner. There is no requirement for additional bias elements to 're-arm' the actuators and allow repetitive actuation. The work generation potential of antagonistic shape memory actuators is determined by specific SMA element characteristics and their assembly conditions. In this study, the selected SMA wires are assembled in antagonistic configuration and characterized using a dedicated test bench to evaluate their stress-strain characteristics as a function of the number of cycles. Using these functional characteristics, a so-called 'working envelope' is built to assist in the design of such an actuator. Finally, the test bench is used to simulate a real application of an antagonistic actuator (case study).
FUNDAMENTAL CHARACTERISTICS AND DESIGN METHOD FOR NICKEL-TITANIUM SHAPE MEMORY ALLOY
paper, 2001
Shape memory alloys (SMA), because of their unique mechanical characteristics and shape memory effect (SME), have been widely used as force and displacement actuators in many fields [DUERING et al, 1990]. In the industrial applications, it is necessary not only to calculate the mechanical response of the actuator in terms of recovery force or deformation, but also to evaluate its temporal characteristics, i.e., the actuation and reset times. This paper presents the fundamental characteristics of SMA and a complete design model, which requires a close connection between three models: a mechanical model to predict the response of the actuator to a given temperature increment, a thermal model to compute the temperature change in the device, and a continuum-mechanical model to predict the martensite fraction on the SMA. The methodology is applied to a linear wire actuator
Flexible Shape-Memory Alloy-Based Actuator: Mechanical Design Optimization According to Application
Actuators
New robotic applications, among others, in medical and related fields, have in recent years boosted research in the development of new actuators in the search for solutions that are lighter and more flexible than conventional actuators. Shape-Memory Alloy (SMA)-based actuators present characteristics that make them an excellent alternative in a wide variety of applications. This paper presents the design, tests (with the control description) and analysis of various configurations of actuators based on SMA wires: flexible SMA actuators, different mechanical design to multiply the displacement and different configurations for actuators with multiple SMA wires. The performance of the actuators has been analyzed using wires of different activation temperatures. The influence of the Bowden sheath of the flexible actuator has been tested, as has the thermal behavior of actuators with several wires. This work has allowed determination of the most effective configuration for the development...