Cooling Strategies for a SMA Wire Actuator in a Feed Axis

2012 ◽  
Author(s):  
Horst Meier ◽  
Jan Pollmann ◽  
Alexander Czechowicz
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Cooling System ◽  
Flow Characteristics ◽  
Electrical Current ◽  
Specific Rate ◽  
Air Cooling ◽  
Intrinsic Resistance ◽  
Feed Axis

Shape memory alloys (SMA) are smart materials which can be activated thermally. They are suitable for the use as actuators due to their ability to remember an imprinted shape through thermal activation. In addition, actuators based on shape memory alloys offer a higher work output in relation to their volume compared to other actuator concepts. Other advantages of using SMA in actuation applications include the ability to design lightweight systems and the comparatively low material costs. On the other hand, designing an SMA actuator poses a challenge in case a specific rate of feed has to be achieved. These difficulties become especially apparent if the actuator is used to create a defined displacement not only in its activation direction, but in the returning (deactivation) direction as well. This might occur, for example, while devising an SMA-driven feed axis. During the activation of the SMA, the speed of the actuator and therefore the speed of the axis can be influenced by choosing a specific thermal energy transfer method. For instance, when using the intrinsic resistance for heating purposes, the speed can be controlled by changing the electrical current running through the SMA. However, after the deactivation (end of the heating phase) of the shape memory alloy, the transformation needs a considerably longer time. For an exemplary SMA wire actuator, the transformation time in room temperature can be five times higher than the activation time. For usage in a feed axis, the actuator should produce similar speeds in both the activation and deactivation direction. To achieve this, different strategies for cooling the SMA after cutting off the current are investigated. These strategies include an active air cooling system with different flow characteristics and the operation of the actuator in a cooling fluid. In a nutshell, the paper compares different ways of cooling an SMA wire actuator to increase the transformation speed after deactivation. The aim is to make the deactivation speed as manageable as the activation speed.

Effects of Annealing on Microstructure and Martensitic Transition of Ni-Mn-Co-In Ferromagnetic Shape Memory Alloys

2011 ◽  
Vol 674 ◽  
pp. 171-175
Author(s):  
Katarzyna Bałdys ◽  
Grzegorz Dercz ◽  
Łukasz Madej
Keyword(s):  
Electron Microscopy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Martensitic Transition ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Initial State ◽  
X Ray ◽  
Ferromagnetic Shape Memory

The ferromagnetic shape memory alloys (FSMA) are relatively the brand new smart materials group. The most interesting issue connected with FSMA is magnetic shape memory, which gives a possibility to achieve relatively high strain (over 8%) caused by magnetic field. In this paper the effect of annealing on the microstructure and martensitic transition on Ni-Mn-Co-In ferromagnetic shape memory alloy has been studied. The alloy was prepared by melting of 99,98% pure Ni, 99,98% pure Mn, 99,98% pure Co, 99,99% pure In. The chemical composition, its homogeneity and the alloy microstructure were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phase composition was also studied by X-ray analysis. The transformation course and characteristic temperatures were determined by the use of differential scanning calorimetry (DSC) and magnetic balance techniques. The results show that Tc of the annealed sample was found to decrease with increasing the annealing temperature. The Ms and Af increases with increasing annealing temperatures and showed best results in 1173K. The studied alloy exhibits a martensitic transformation from a L21 austenite to a martensite phase with a 7-layer (14M) and 5-layer (10M) modulated structure. The lattice constants of the L21 (a0) structure determined by TEM and X-ray analysis in this alloy were a0=0,4866. The TEM observation exhibit that the studied alloy in initial state has bigger accumulations of 10M and 14M structures as opposed from the annealed state.

Adaptive Elastic SMA Elements for Damping Applications

2013 ◽  
Author(s):  
Alexander Czechowicz ◽  
Peter Dültgen ◽  
Sven Langbein
Keyword(s):  
Boundary Conditions ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Electrical Resistance ◽  
Thermal Activation ◽  
Hysteretic Behavior ◽  
Damping Function ◽  
Actual Shape ◽  
Elastic Elements

Shape memory alloys (SMA) are smart materials, which have two technical usable effects: While pseudoplastic SMA have the ability to change into a previously imprinted actual shape through the means of thermal activation, pseudoelastic SMA show a reversible mechanical elongation up to 8% at constant temperature. The transformation between the two possible material phases (austenite and martensite) shows a hysteretic behavior. As a result of these properties, SMA can be used as elastic elements with intrinsic damping function. Additionally the electrical resistance changes remarkably during the material deformation. These effects are presented in the publication in combination with potential for applications in different branches at varying boundary conditions. The focus of the presented research is concentrated on the application of elastic elements with adaptive damping function. As a proof for the potential considerations, an application example sums up this presentation.

Modeling Smart Materials Using Hysteretic Recurrent Neural Networks

2009 ◽  
Author(s):  
Arun Veeramani ◽  
John Crews ◽  
Gregory D. Buckner
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Real Time Control ◽  
Ferromagnetic Shape Memory Alloys ◽  
Two Phase ◽  
Time Control ◽  
Novel Approach ◽  
Three Phase ◽  
Ferromagnetic Shape Memory

This paper describes a novel approach to modeling hysteresis using a Hysteretic Recurrent Neural Network (HRNN). The HRNN utilizes weighted recurrent neurons, each composed of conjoined sigmoid activation functions to capture the directional dependencies typical of hysteretic smart materials (piezoelectrics, ferromagnetic, shape memory alloys, etc.) Network weights are included on the output layer to facilitate training and provide statistical model information such as phase fraction probabilities. This paper demonstrates HRNN-based modeling of two- and three-phase transformations in hysteretic materials (shape memory alloys) with experimental validation. A two-phase network is constructed to model the displacement characteristics of a shape memory alloy (SMA) wire under constant stress. To capture the more general thermo-mechanical behavior of SMAs, a three-phase HRNN model (which accounts for detwinned Martensite, twinned Martensite, and Austensite phases) is developed and experimentally validated. The HRNN modeling approach described in this paper readily lends itself to other hysteretic materials and may be used for developing real-time control algorithms.

Shape memory alloy–actuated prestressed composites with application to morphing automotive fender skirts

2018 ◽  
Vol 30 (3) ◽  
pp. 479-494 ◽  
Author(s):  
Venkata Siva C Chillara ◽  
Leon M Headings ◽  
Ryohei Tsuruta ◽  
Eiji Itakura ◽  
Umesh Gandhi ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Design Procedure ◽  
Building Blocks ◽  
Smart Composite ◽  
Thermally Induced ◽  
One Dimensional ◽  
Flat Shape

This work presents smart laminated composites that enable morphing vehicle structures. Morphing panels can be effective for drag reduction, for example, adaptive fender skirts. Mechanical prestress provides tailored curvature in composites without the drawbacks of thermally induced residual stress. When driven by smart materials such as shape memory alloys, mechanically-prestressed composites can serve as building blocks for morphing structures. An analytical energy-based model is presented to calculate the curved shape of a composite as a function of force applied by an embedded actuator. Shape transition is modeled by providing the actuation force as an input to a one-dimensional thermomechanical constitutive model of a shape memory alloy wire. A design procedure, based on the analytical model, is presented for morphing fender skirts comprising radially configured smart composite elements. A half-scale fender skirt for a compact passenger car is designed, fabricated, and tested. The demonstrator has a domed unactuated shape and morphs to a flat shape when actuated using shape memory alloys. Rapid actuation is demonstrated by coupling shape memory alloys with integrated quick-release latches; the latches reduce actuation time by 95%. The demonstrator is 62% lighter than an equivalent dome-shaped steel fender skirt.

Smart materials: Properties, design and mechatronic applications

2016 ◽  
Vol 233 (4) ◽  
pp. 734-762 ◽  
Author(s):  
A Spaggiari ◽  
D Castagnetti ◽  
N Golinelli ◽  
E Dragoni ◽  
G Scirè Mammano
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Piezoelectric Materials ◽  
Magnetorheological Fluids ◽  
Research Perspective ◽  
Active Devices ◽  
Complete Survey ◽  
Basic Equations ◽  
Commercial Applications

This paper describes the properties and the engineering applications of the smart materials, especially in the mechatronics field. Even though there are several smart materials which all are very interesting from the research perspective, we decide to focus the work on just three of them. The adopted criterion privileges the most promising technologies in terms of commercial applications available on the market, namely: magnetorheological fluids, shape memory alloys and piezoelectric materials. Many semi-active devices such as dampers or brakes or clutches, based on magnetorheological fluids are commercially available; in addition, we can trace several applications of piezo actuators and shape memory-based devices, especially in the field of micro actuations. The work describes the physics behind these three materials and it gives some basic equations to dimension a system based on one of these technologies. The work helps the designer in a first feasibility study for the applications of one of these smart materials inside an industrial context. Moreover, the paper shows a complete survey of the applications of magnetorheological fluids, piezoelectric devices and shape memory alloys that have hit the market, considering industrial, biomedical, civil and automotive field.

Phenomenological Models of Solid State Actuators for Network Based System Modelling

2014 ◽  
Author(s):  
Johannes Ziske ◽  
Fabian Ehle ◽  
Holger Neubert
Keyword(s):  
Solid State ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Magnetic Flux Density ◽  
System Modelling ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Design And Optimization ◽  
Highly Nonlinear

Smart materials, such as thermal or magnetic shape memory alloys, provide interesting characteristics for new solid state actuators. However, their behavior is highly nonlinear and determined by strong hysteresis effects. This complex behavior must be adequately considered in simulation models which can be applied for efficient actuator design and optimization. We present a new phenomenological lumped element model for magnetic shape memory alloys (MSM). The model takes into account the two-dimensional hysteresis of the magnetic field induced strain as a function of both the compressive stress and the magnetic flux density. It is implemented in Modelica. The model bases on measured limiting hysteresis surfaces which are material specific. An extended Tellinen hysteresis modeling approach is used to calculate inner hysteresis trajectories in between the limiting surfaces. The developed model provides sufficient accuracy with low computational effort compared to finite element models. Thus, it is well suited for system design and optimization based on network models. This is demonstrated with exemplary models of MSM based actuators. System models and simulation results are shown and evaluated for different topologies.

scholarly journals Development of Smart Textile Materials with Shape Memory Alloys for Application in Protective Clothing

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 689 ◽  
Author(s):  
Grażyna Bartkowiak ◽  
Anna Dąbrowska ◽  
Agnieszka Greszta
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Protective Clothing ◽  
Radiant Heat ◽  
Textile Material ◽  
Material System ◽  
Molten Metals ◽  
Textile Materials ◽  
Smart Textile

The latest directions of research on the design of protective clothing concern the implementation of smart materials, in order to increase its protective performance. This paper presents results on the resistance to thermal factors such as flames, radiant heat, and molten metals, which were obtained for the developed smart textile material with shape memory alloys (SMAs). The laboratory tests performed indicated that the application of the designed SMA elements in the selected textile material system caused more than a twofold increase in the resistance to radiant heat (RHTI24 = 224 s) with an increase of thickness of 13 mm (sample located vertically with a load), while in the case of tests on the resistance to flames, it was equal to 41 mm (sample located vertically without a load) and in the case of tests on the resistance to molten metal, it was 17 mm (sample located horizontally).

The Role of Shape Memory Alloys in Smart/Adaptive Structures

1991 ◽  
Vol 246 ◽  
Author(s):  
L. McD. Schetky
Keyword(s):  
Composite Materials ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Dynamic Characteristics ◽  
Smart Materials ◽  
Acoustic Radiation ◽  
Sensors And Actuators ◽  
Adaptive Structures ◽  
Distributed Sensors ◽  
Shape Memory Actuators

AbstractAdaptive structures, also called Intelligent or smart materials, refers to the various materials systems which automatically or remotely alter their dynamic characteristics or their geometry to meet their Intended performance. By integrating the sensors and actuators Into the structural system, typically a composite materials, control of shape, vibration and acoustic behavior an be effected. In addition to active control, passive control of system damping can be achieved in these structures. The sensors employed include piezoelectric ceramics, piezoelectric polymer films, ferroelectrics, and fiber optics. For producing the stress induced changes in dynamic characteristics of a composite the actuators are either embedded within the composite or are surface mounted. In general, the piezoelectric type actuator Is used where small strains at high frequencies are appropriate, while shape memory actuators are used when high forces and strains at lower frequencies are required. Static damping, modulus shift effect on acoustic radiation, and strain energy shift of modal response and acoustic radiation of composite materials with embedded shape memory actuators will be discussed. The constitutive equations for shape memory alloys will be described and how these are used in the design of adaptive composite structuresThe term smart materials seems to have become a part of the engineering vocabulary with variants such as Intelligent materials, and their application in adaptive structures. Smart materials consist of a structural component such as a composite such as fiber reenforced resin, with distributed sensors and actuators and a microprocessor. In response to changing external or Internal conditions these materials can change their properties to more effectively perform their function. The external conditions may be environment such as light or heat, loads, vibration or the need to change the geometry or shape of the structure to cope with changing service conditions. Internal conditions may be delamination in a composite, fatigue cracks in a metallic or nonmetallic structure, or other forms of Incipient failure.In reviewing papers presented in the past several years at conferences on smart/adaptive structures one would see a dominant number on various aspects of space structures such as mirrors. antennas, robotics booms and satellite docking. In these areas the control of vibration or the precise control of motion are most often the specific subject addressed. Much of the ongoing research is on control theory and the design of algorithms to define the sensor-actuator-microprocessor Integration. Of concern in this paper Is the actuator itself which, in response to commands from the microprocessor, produces strains and forces in the structure to modify Its acoustic or vibratory response or alter Its shape. These actuators are broadly of two types: low to medium force, low strain, high frequency systems, typically a piezoceramic such as PZT, or a high force, high strain, low frequency actuator which is most likely to be a shape memory alloy element.

Experimental investigation of vibration reduction using shape memory alloys

2012 ◽  
Vol 24 (2) ◽  
pp. 247-261 ◽  
Author(s):  
Ricardo AA Aguiar ◽  
Marcelo A Savi ◽  
Pedro MCL Pacheco
Keyword(s):  
Dynamical Systems ◽  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Experimental Analysis ◽  
Vibration Reduction ◽  
Dynamical Response ◽  
Temperature Variations ◽  
Experimental Apparatus

Smart materials have a growing technological importance due to their unique thermomechanical characteristics. Shape memory alloys belong to this class of materials being easy to manufacture, relatively lightweight, and able to produce high forces or displacements with low power consumption. These aspects could be exploited in different applications including vibration control. Nevertheless, literature presents only a few references concerning the experimental analysis of shape memory alloy dynamical systems. This contribution deals with the experimental analysis of shape memory alloy dynamical systems by considering an experimental apparatus consisted of low-friction cars free to move in a rail. A shaker that provides harmonic forcing excites the system. The vibration analysis reveals that shape memory alloy elements introduce complex behaviors to the system and that different thermomechanical loadings are of concern showing the main aspects of the shape memory alloy dynamical response. Special attention is dedicated to the analysis of vibration reduction that can be achieved by considering different approaches exploiting either temperature variations promoted by electric current changes or vibration absorber techniques. The results establish that adaptability due to temperature variations is defined by a competition between stiffness and hysteretic behavior changes.

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