Evaluation of the characteristics of a shape memory alloy spring actuator (original) (raw)
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On the design of a shape memory alloy spring actuator using thermal analysis
WSEAS TRANSACTIONS on SYSTEMS archive, 2008
Due to their unique properties and behavior, the Shape Memory Alloys (SMAs) play an increasingly important role in the intelligent systems performance. Recent applications in structural actuation and sensing demand increased material capabilities. This paper reviews the main advantages and the properties of SMAs and presents the design strategy for a typical shape memory actuator configuration of intelligent systems, using as active element Ni-Ti SMA spring working against a conventional steel spring. It also includes the thermal analysis experiments, in order to determine the transformation temperatures for the studied SMA spring. For design optimization a comprehensive graphical interface (based on the thermal analysis results), which runs under Visual Basic, has been developed for this application. It provides a user friendly environment allowing intelligent system parameters configuration as well as choosing the most adapted analysis methods and data displaying.
Evaluation of the characteristics of a shape memory alloy cantilever actuator using thermal analysis
Recent Advances in …
The article presents the thermal characteristics evaluation of a typical intelligent system actuator using as active element the Shape Memory Alloy (SMA) helical spring. In order to determine the transformation temperatures and other thermal parameters of the studied element, the attention was concentrated on thermal analysis experiments. For the actuator configuration, a comprehensive graphical interface has been developed, to run in Visual Basic, with respect to the results of performed thermal analyses.
Shape Memory Alloy Helical Springs Performance: Modeling and Experimental Analysis
Materials Science Forum, 2013
Shape memory alloys (SMAs) are metallic materials that have the capability to recover its original shape eliminating residual strains when subjected to adequate thermal process. This behavior is related to phase transformation induced either by stress or by. During the phase transformation process of an SMA component, large loads and/or displacements can be generated in a relatively short period of time making this component an interesting mechanical actuator. Because of such remarkable properties, SMAs have found a number of applications in different areas. The present contribution deals with the modeling, simulation and experimental analysis of SMA helical springs. Basically, it is assumed a one-dimensional constitutive model to describe its thermomechanical shear behavior and, afterwards, helical springs are modeled by considering classical approach. SMA helical spring thermomechanical behavior is investigated through experimental tests performed at different loads. Numerical results show that the model is in close agreement with experimental data. Since the thermal process has an essential importance in the performance of an SMA actuator, different cooling medium conditions are investigated, evaluating the actuators performance.
Defence Science Journal, 2016
The optimal design and analysis of hot water actuated shape memory alloy spring is presented. Smart materials exhibit special properties that make them a preferred choice for industrial applications in many branches of engineering. The serviceable properties of a Ni-Ti piece can be improved by altering the energy source. With hot water actuation, as the temperature reaches 70 °C - 90 °C, spring gets fully compressed for the first few cycles followed by loss in actuation. The actuation loss is then studied with different characterisation methods such as thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). With SEM results, it can be strongly recommended that the energy source is sufficient for actuation (not affecting too much the structure). Results observed from TGA shows high oxygen content at lower temperature, suggest the need of conducting experiments in inert atmosphere. For the validation of hot water actuation, comparative analysis between electrical and...
Experimental investigation of the influence of the heating rate in an SMA actuator performance
Sensors and Actuators A: Physical, 2013
The use of shape memory alloys (SMAs) as actuators has an increasing importance in several areas. In general, the shape memory effect and the two-way shape memory effect are employed in order to produce displacements and/or forces by heating the SMA actuator above the phase transformation temperature. This paper presents an experimental investigation on the heating rate influence on an SMA actuator. Basically, an experimental apparatus is built by considering NiTi wire connected to a steel spring and monitored by sensors. The heating rate varies from 2.9 • C/min to 385 • C/min by applying an electrical current in the SMA actuator. Several situations are investigated highlighting the general thermomechanical behavior associated with the influence of heating rate.
Shape memory alloy helical springs: modeling, simulation and experimental analysis
2009
Shape memory alloys (SMAs) are metallic materials that have the capability to recover its original shape eliminating residual deformations when subjected to adequate thermal process. This behavior is related to phase transformation induced by stress or temperature and several alloys present this behavior. During the phase transformation process of a SMA component, large loads and/or displacements can be generated in a relatively short period of time making this component an interesting mechanical actuator. Because of such remarkable properties, SMAs have found a number of applications in different areas. The present contribution deals with the modeling, simulation and experimental analysis of SMA helical springs. Basically, it is assumed a one-dimensional constitutive model to describe its thermomechanical shear behavior and, afterwards, helical springs are modeled by considering classical approach. A numerical method based on the operator split technique is developed. SMA helical spring thermomechanical behavior is investigated through experimental tests performed at different loads. Numerical results show that the model is in close agreement with those obtained by experimental tests.
Thermomechanical Analysis on Ti-Ni Shape Memory Helical Springs Under Cyclic Tensile Loads
Materials Research, 2015
Shape memory alloys (SMAs) present some characteristics, which make it unique material to be use in applications that require strength and shape recovery. This alloys was been used to manufacture smart actuators for mechanical industry devices and several other applications in areas as medicine, robotics, aerospace, petroleum and gas industries. However it is important to know the actuators response to external stimulus (heat source, electrical current and/or external stress) in these technological applications. This work investigated the thermomechanical behaviors of helical actuators produced from Ti-Ni alloy commercial wires. Initially, the wire was subjected to some heat treatment and characterized by differential scanning calorimeter (DSC), scanning electron microscopy (SEM), optical microscopy (OM) and Energy dispersive spectroscopy. Then two heat treatments were selected to obtain the helical actuators. The actuators were tested in an apparatus developed to apply an external traction stress in helical actuators during thermal cycles. Two wires were tested in a dynamic mechanical analyzer (DMA). The results were analyzed in comparison with thermoplastic properties obtained in thermomechanical tests. The analysis took into consideration the wiring forming process, the precipitates formation, the stress fields generated by dislocations and reorientation of martensite variants during the actuators training process.
Experimental and numerical investigations of shape memory alloy helical springs
Smart Materials and Structures, 2010
Shape memory alloys (SMAs) belong to the class of smart materials and have been used in numerous applications. Solid phase transformations induced either by stress or temperature are behind the remarkable properties of SMAs that motivate the concept of innovative smart actuators for different purposes. The SMA element used in these actuators can assume different forms and a spring is an element usually employed for this aim. This contribution deals with the modeling, simulation and experimental analysis of SMA helical springs. Basically, a one-dimensional constitutive model is assumed to describe the SMA thermomechanical shear behavior and, afterwards, helical springs are modeled by considering a classical approach for linear-elastic springs. A numerical method based on the operator split technique is developed. SMA helical spring thermomechanical behavior is investigated through experimental tests performed with different thermomechanical loadings. Shape memory and pseudoelastic effects are treated. Numerical simulations show that the model results are in close agreement with those obtained by experimental tests, revealing that the proposed model captures the general thermomechanical behavior of SMA springs.
A computational and experimental study of shape memory alloy spring actuator
PRZEGLĄD ELEKTROTECHNICZNY
The paper presents the combined experimental and computational study of the shape memory alloy (SMA) spring actuator. The design strategy for a system composed of two springs: a SMA spring and a steel spring has been presented. The force versus stroke characteristics of designed system at high and low temperature condition have been calculated and measured. The electro-thermo-mechanical characterization of SMA spring has been carried out. The selected results of calculation and laboratory tests of the designed spring system have been given. Streszczenie. W pracy przedstawiono wyniki obliczeń i badań eksperymentalnych siłownika sprężynowego wykonanego ze stopu z pamięcią kształtu. Omówiono zaproponowaną strategię projektowania systemu składającego się z dwóch sprężyn: sprężyny SMA i sprężyny stalowej. Wyznaczono i zmierzono charakterystykę siły w funkcji przesunięcia dla stanu wysoko i niskotemperaturowego. Zaprojektowano specjalne stanowisko pomiarowe do badań elektro-cieplno-mechanicznych sprężyny SMA i układu złożonego ze sprężyny SMA i sprężyny stalowej. Przedstawiono wybrane wyniki obliczeń i badań laboratoryjnych zaprojektowanego układu sprężyn (Modelowanie i eksperymentalne badania siłownika sprężynowego wykonanego ze stopu z pamięcią kształtu).