scholarly journals Theoretical and Experimental Study of a Thermo-Mechanical Model of a Shape Memory Alloy Actuator Considering Minor Hystereses

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1120
Author(s):  
Rosen Mitrev ◽  
Todor Todorov ◽  
Andrei Fursov ◽  
Borislav Ganev
Keyword(s):  
Mathematical Model ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Model ◽  
Pulse Width Modulation ◽  
Classical Model ◽  
Experimental Studies ◽  
Physical Factors ◽  
In Series ◽  
Displacement Force

The paper presents a theoretical and experimental investigation of a thermo-mechanical model of an actuator composed of a shape memory alloy wire arranged in series with a bias spring. The developed mathematical model considers the dynamics of the actuator in the thermal and mechanical domains. The modelling accuracy is increased through the developed algorithm for modelling the minor and sub minor hystereses, thus removing the disadvantages of the classical model. The algorithm improves the accuracy, especially when using pulse-width modulation control, for which minor and sub minor hystereses are likely to occur. Experimental studies show that the system is very sensitive, and there are physical factors whose presence cannot be considered in the mathematical model. The experimental research has shown that setting constant values of the duty cycle is impossible to obtain a stable value of displacement and force. The comparison between the developed mathematical model results and the experimental results shows that the differences are acceptable. The improved modelling serves as a basis for designing such actuators and creating an improved automatic feedback control system to maintain a given displacement (force) or trajectory tracking.

Feasibility of Shape Memory Alloy Wire Actuation for an Active Steerable Cannula

2015 ◽  
Vol 9 (2) ◽  
Author(s):  
Bardia Konh ◽  
Naresh V. Datla ◽  
Parsaoran Hutapea
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Breast Biopsy ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Needle Insertion ◽  
Design Parameters ◽  
Fe Model ◽  
In Series ◽  
Steerable Cannula

Needle insertion is used in many diagnostic and therapeutic percutaneous medical procedures such as brachytherapy, thermal ablations, and breast biopsy. Insufficient accuracy using conventional surgical cannulas motivated researchers to provide actuation forces to the cannula's body for compensating the possible errors of surgeons/physicians. In this study, we present the feasibility of using shape memory alloy (SMA) wires as actuators for an active steerable surgical cannula. A three-dimensional (3D) finite element (FE) model of the active steerable cannula was developed to demonstrate the feasibility of using SMA wires as actuators to bend the surgical cannula. The material characteristics of SMAs were simulated by defining multilinear elastic isothermal stress–strain curves that were generated through a matlab code based on the Brinson model. Rigorous experiments with SMA wires were done to determine the material properties as well as to show the capability of the code to predict a stabilized SMA transformation behavior with sufficient accuracy. In the FE simulation, birth and death method was used to achieve the prestrain condition on SMA wire prior to actuation. This numerical simulation was validated with cannula deflection experiments with developed prototypes of the active cannula. Several design parameters affecting the cannula's deflection such as the cannula's Young's modulus, the SMA's prestrain, and its offset from the neutral axis of the cannula were studied using the FE model. Real-time experiments with different prototypes showed that the quickest response and the maximum deflection were achieved by the cannula with two sections of actuation compared to a single section of actuation. The numerical and experimental studies showed that a highly maneuverable active cannulas can be achieved using the actuation of multiple SMA wires in series.

A thermo-mechanical model for shape memory alloy–based crank heat engines

2014 ◽  
Vol 26 (6) ◽  
pp. 652-662
Author(s):  
Fabrizio Niccoli ◽  
Carmine Maletta ◽  
Emanuele Sgambitterra ◽  
Franco Furgiuele
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Model ◽  
Heat Engines

Optimal H∞ Control of Structural Vibrations Using Shape Memory Alloy Actuators

1999 ◽  
Author(s):  
Jian Sun ◽  
Ali R. Shahin
Keyword(s):  
Mathematical Model ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Model Uncertainty ◽  
High Frequency ◽  
Structural Vibrations ◽  
Design Procedures ◽  
Sma Actuators ◽  
Temperature Dynamics ◽  
The Mathematical Model

Abstract This paper investigates robust control problem of structural vibrations using shape memory alloy (SMA) wires as actuators. The mathematical model for these SMA actuators is derived with emphasis in model uncertainty. The linearization of the relation between stress and temperature dynamics of SMA actuators is analyzed for active control. To handle the uncertainties caused by the linearization and the neglected high frequency dynamics, optimal H∞ control was employed to design a controller. An example is used to demonstrate the design procedures and the control system is tested in a nonlinear environment.

scholarly journals A Tetra-State Hopping Robot Driven by Shape Memory Alloy Spring

2011 ◽  
Vol 2-3 ◽  
pp. 402-407 ◽  
Author(s):  
Tian Qi Liu ◽  
Shu Ping Chen ◽  
Jiang Long Guo ◽  
Zhi Long Dou ◽  
Chun Liu ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Model ◽  
Lagrange Method ◽  
Hopping Robot ◽  
Jumping Robot

According to the characteristics of jumping locomotion, a solution of Tetra-state Hopping Robot (for short: THR) actuated by Shape Memory Alloy Spring (for short: SMAS) is presented in this paper. This article establishes a mechanical model of the jumping robot and analyzes the kinematics and the dynamics of the mechanical model. Lagrange method is applied to analyze the dynamics the mechanical model. Meanwhile, a preliminary explanation of the THR flipping phenomenon during the take-off and flight process is conducted from the perspective of momentum moment.

Discrete Preisach Model of a Shape Memory Alloy Actuator

2016 ◽  
Vol 248 ◽  
pp. 227-234
Author(s):  
Waldemar Rączka ◽  
Jarosław Konieczny ◽  
Marek Sibielak ◽  
Janusz Kowal
Keyword(s):  
Mathematical Model ◽  
Shape Memory Alloy ◽  
Parameter Identification ◽  
Shape Memory ◽  
Preisach Model ◽  
Discrete Form ◽  
Nonlinear Characteristics ◽  
Shape Memory Alloy Actuator ◽  
Sma Actuator ◽  
Identification Model

Shape Memory Alloy is a material used to designing actuators. These actuators have many advantages. They are light, strong and silent. They are building in laboratory and tested because beside advantages they have disadvantages too. SMA actuators have nonlinear characteristics with hysteresis loop.In the first part of the paper Shape Memory Alloys are shortly described. Next mathematical model was formulated. In the paper the Preisach model was developed. Discrete form of the model was considered and implemented. After parameter identification model was implemented in LabView. Tests of the model were conducted and results were worked. Obtained characteristics of the SMA actuator are shown in the paper. At the end of the paper the conclusions were formulated.

scholarly journals Flexible Fingers Based on Shape Memory Alloy Actuated Modules

Machines ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 40 ◽  
Author(s):  
Daniela Maffiodo ◽  
Terenziano Raparelli
Keyword(s):  
Mathematical Model ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Basic Concept ◽  
Experimental Tests ◽  
Simple Mathematical Model ◽  
Joule Effect ◽  
Antagonistic Action ◽  
Preliminary Results

To meet the needs of present-day robotics, a family of gripping flexible fingers has been designed. Each of them consists of a number of independent and flexible modules that can be assembled in different configurations. Each module consists of a body with a flexible central rod and three longitudinally positioned shape memory alloy (SMA) wires. When heated by the Joule effect, one to two SMA wires shorten, allowing the module to bend. The return to undeformed conditions is achieved in calm air and is guaranteed by the elastic bias force exerted by the central rod. This article presents the basic concept of the module and a simple mathematical model for the design of the device. Experimental tests were carried out on three prototypes with bodies made of different materials. The results of these tests confirm the need to reduce the antagonistic action of the inactive SMA wires and led to the realization of a fourth prototype equipped with an additional SMA wire-driven locking/unlocking device for these wires. The preliminary results of this last prototype are encouraging.

Design Framework for Multi-Section Shape Memory Alloy Axial Actuators Considering Material and Geometric Uncertainties

2020 ◽  
Author(s):  
Weilin Guan ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Energy ◽  
High Energy Density ◽  
Design Framework ◽  
Efficient Design ◽  
Cross Sectional ◽  
Geometric Uncertainties ◽  
In Series ◽  
The Wire

Abstract Shape memory alloys are metallic materials with the capability of performing as high energy density actuators driven by temperature control. This paper presents a design framework for shape memory alloy (SMA) axial actuators composed of multiple wire sections connected in series. The various wire sections forming the actuators can have distinct cross-sectional areas and lengths, which can be modulated to adjust the overall thermomechanical response of the actuator. The design framework aims to find the optimal cross-sectional areas and lengths of the wire sections forming the axial actuator such that its displacement vs. temperature actuation path approximates a target path. Constraints on the length-to-diameter aspect ratio and stress of the wire sections are incorporated. A reduced-order numerical model for the multi-section SMA actuators that allows for efficient design evaluations is derived and implemented. An approach to incorporate uncertainty in the geometry and material parameters of the actuators within the design framework is implemented to allow for the determination of robust actuator designs. A representative application example of the design framework is provided illustrating the benefits of using multiple wire sections in axial actuators to modulate their overall response and approximate a target displacement vs. temperature actuation path.

A Novel Design of a Large-Stroke Shape Memory Alloy Linear Actuator

2019 ◽  
Author(s):  
Fei Yang ◽  
Jian Wang ◽  
Miaoling Han ◽  
Yifan Lu ◽  
Honghao Yue ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Linear Actuator ◽  
Confined Space ◽  
Output Displacement ◽  
Tandem Structure ◽  
In Series ◽  
Sma Actuator ◽  
Application Fields ◽  
Actuation Systems

Abstract The traditional actuation systems such as combustion engines, electro motors, hydraulic and pneumatic machines, have several drawbacks: large volume and weight, huge energy consumption and high cost. To overcome these problems, this paper presents a novel large-stroke linear actuator actuated by shape memory alloy (SMA) wires. Multiple SMA wires are distributed in the space three-dimensionally and connected in series to achieve a larger stroke of the actuator. The tandem structure makes the SMA actuator easy to integrate into a narrow available space with dimension constraints. A theoretical model for bias element selection is developed through analysis of the driving paths. A prototype of the proposed SMA actuator is fabricated and corresponding experiments are conducted to verify the functions and performances. The critical working performances of the SMA actuator such as the output displacement, heating electric current, actuation time and reset time are obtained and investigated. The results prove that the proposed SMA actuator can output an ideal driving stroke and enough actuation force in confined space. This research provides design ideas for the large-stroke SMA actuator in more application fields.

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