Resistance Characteristics of SMA Actuator Based on the Variable Speed Phase Transformation Constitutive Model

Thermal Investigation and Optimized Design of a Novel Solar Self-Driven Thermomechanical Actuator

As the world moves toward cleaner and greener sources of energy, the use of solar energy appeals the most for countries in the Middle East and North Africa (MENA) region, since they have an abundant amount of solar radiation throughout the year. This paper offers a novel design for a shape memory alloy (SMA) actuator that uses solar energy to trigger thermomechanical behavior. Additionally, the proposed design of the thermomechanical actuator aims to be a piston-based linear actuator covered by a solar heat collector (SHC). Furthermore, the thermal behavior of the actuator has been studied in detail using a simulation-based study under the real-time weather conditions of Dammam city, Kingdom of Saudi Arabia (KSA). The thermal study proves that the optimized design of the thermomechanical actuator has achieved a minimum daily temperature variation of 10 °C, which enables the SMA-based thermomechanical actuator to operate in a daily manner throughout the year. Moreover, the presented numerical results show that the proposed thermomechanical actuator requires a twice-maintenance routine yearly. Additionally, it has been observed that the SHC, which is the central part of the designed thermomechanical actuator, can increase the temperature inside the actuator by about 15 °C more than ambient temperature. The proposed study adds to the body of knowledge a design for a passive, solar-driven, and self-actuating smart thermomechanical SMA actuator that is capable of integration with various solar applications, such as the cleaning and tracking of photovoltaic systems.

Development of a Combined Micro-Macro Mechanics Analytical Approach to Design Shape Memory Alloy Spring-Based Actuators and Its Experimental Validation

In this work, an analytical procedure for the preliminary design of shape memory alloy spring-based actuators is investigated. Two static analytical models are considered and interconnected in the frame of the proposed procedure. The first model, based on the works from An, is able to determine the material properties of the SMA components by means of experimental test data and is able to size the SMA component based on the requirements of the system. The second model, based on a work from Spaggiari, helps to design and size an antagonist spring system that allows one to obtain the geometric characteristics of springs (SMA and bias) and the mechanical characteristics of the entire actuator. The combined use of these models allows one to define and size a complex SMA actuator based on the actuation load requirements. To validate the design procedure, static experimental tests have been performed with the entire SMA actuator.

Development of Hybrid Prandtl–Ishlinskii and Constitutive Models for Hysteresis of Shape-Memory-Alloy-Driven Actuators

Prandtl–Ishlinskii (PI) model has an excellent compromise to characterize an asymmetric saturated hysteresis behavior of shape-memory-alloy (SMA)-driven systems, but it cannot consider thermomechanical relations between components of SMA-driven systems. On the other hand, constitutive models are composed of these relations, but their precision needs to be improved. In this paper, PI model is proposed to boost constitutive models in two cases. In the first case, PI model is used to characterize martensite volume fraction (MVF) called hybrid model. In the second case, the model is applied as a regulator in the output of a constitutive model called PI-based output (PIO) regulator. Due to simplicity and ability of Liang–Rogers (LR) model in transformation phases, it is considered as an MVF in the original constitutive model. The performance of both proposed models is compared with the original LR-based constitutive model. Unknown parameters of all three models are identified using genetic algorithm in MATLAB Toolbox. The performance of the three models is investigated at three different frequencies of \[\frac{{2\pi }}{8}\] , \[\frac{{2\pi }}{{15}}\] , and \[\frac{{2\pi }}{{30}}\] Hz because the excitation frequency changes the hysteresis behavior. Results show that the proposed hybrid model keeps the precision of the original constitutive model at different frequencies. In addition, the proposed PIO model shows the best performance to predict hysteresis behavior at different frequencies.