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

Mitrev, Rosen; Todorov, T.; Fursov, A. S.; Ganev, Borislav

doi:10.3390/cryst11091120

Cited by 8 publications

(10 citation statements)

References 38 publications

(41 reference statements)

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“…The relative martensitic fraction m R of NiTi is calculated according to [32,37], and to investigate the major and minor hysteresis similarly to [18] it is modified in the form…”

Section: Building a Dynamic Model And Determining The Input Data For ...mentioning

confidence: 99%

“…This behavior is used to create relatively low-cost actuators that possess several advantages such as generating large forces and displacements at high energy density and noiselessness. Thermal activation of SMAs creates conditions for cyclic control [18][19][20] and in many cases for self-excitation of thermomechanical oscillations [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Study of Self-Excited Thermomechanical Oscillator with Shape Memory Alloys

Yotov,

Todorov,

Todorov

2024

Preprint

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In this paper, a new type of self-excited thermomechanical oscillator containing an oscillating shape memory alloy (SMA) filament with two symmetrically arranged spheres is investigated. The self-excitation of the oscillations is due to a heater of constant temperature, which causes periodic contractions of the filament when it approaches it. The contracted filament moves away from the heater a distance sufficient to cool it. Under the action of the weight of the spheres, the cooled filament re-approaches the heater, causing the above processes to repeat periodically. On the basis of experimental studies, approximating functions of the heater's heat field distribution are derived. A dynamic model of the oscillator has been created, in which the minor and major hysteresis in the SMA alloy and the distribution of the heat field around the heater have been taken into account. By numerical solutions of the differential equations, the laws of motion of the spheres are obtained. The displacements of the spheres in two perpendicular directions were measured using an experimental system. The obtained experimental results validate the proposed dynamic model and its assumptions with a high degree of confidence. Conclusions are drawn about the stochastic nature of the oscillations due to the hysteresis properties of the SMA and the temperature variation of the natural frequency of the oscillating system.

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“…The relative martensitic fraction m R of NiTi is calculated according to [32,37], and to investigate the major and minor hysteresis similarly to [18] it is modified in the form…”

Section: Building a Dynamic Model And Determining The Input Data For ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of Self-Excited Thermomechanical Oscillator with Shape Memory Alloys

Yotov,

Todorov,

Todorov

2024

Preprint

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“…SMA's composition helps provide several mechanical properties like ductility, corrosion resistance, and memory [38]. It is a unique material that varies its shape, frequency, and stiffness with the variation of thermal load, which leads to the wide application of shape memory alloys [39,40]. SMAs are extensively considered as force and linear displacement actuators because of their unique mechanical properties, silent actuation, high energy density, and shape memory effect (SME).…”

Section: Design Of Shape Memory Alloy (Sma) Linear Actuator and Perfo...mentioning

confidence: 99%

“…The maximum recoverable strain is constant for a specific SMA. In addition, SMA actuators are getting more popular due to their compactness with low-voltage activation and the larger power-to-mass ratio [40]. The difference between forward and backward transition paths causes hysteresis.…”

Section: Design Of Shape Memory Alloy (Sma) Linear Actuator and Perfo...mentioning

confidence: 99%

Design development and control of a shape memory alloy linear actuation based XYθ motion stage

Choudhury

Singh

2023

Eng. Res. Express

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This article addresses the development and trajectory tracking analysis of the three degrees of freedom Shape memory alloy (SMA) actuation-based 4-PPR XYθ motion stage. The developed motion stage is of four legs of the PPR (Prismatic-Prismatic-Revolute) configuration, having the first prismatic joint as the active joint. SMA spring is incorporated as the linear actuator of the motion stage. The three degrees of freedom motion of the end-effector is achieved based on a new type of SMA-driven PPR joint configuration to provide two translations and one rotational motion. The advantages of the SMA as an actuator is such as lightweight, higher accuracy, and micron-level movement to establish linear motion and silent actuation. The kinematic and jacobian relations are derived for the developed motion stage. The actuation of the SMA (Nitinol) spring actuator is accomplished by the use of a programmable power supply. In addition, the close loop PID control scheme to the SMA linear actuator is investigated. The mechanism has some inherent errors, as geometric errors (kinematic error), friction between the elements of the mechanism, etc., are significant issues in tracking the trajectory of the motion stage. Thus, to address the above issues, this study incorporates the dual-loop control scheme for better trajectory tracking and error compensation of the proposed motion stage. The control method employs a redundant feedback approach, in which discrete joint space displacements and mobile platform coordinates, and task space coordinates are determined as feedback signal using suitable sensors. In this control scheme, the actual joint displacement errors are computed using the redundant feedback data and corrected the desired joint displacement trajectory to obtain the desired task space trajectory. To measure the effectiveness of the used control scheme, a real-time prototype of the proposed motion stage (4-PPR) is developed and investigated the performance of the control method using some simple geometric trajectories. It is observed from the experiments that the motion stage using SMA linear actuation technique has good tracking performance using the control scheme. The developed motion stage can be implemented in the micro-stereolithography process and micron-level positioning application.

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“…The One-Way Shape Memory Effect requires pre-deformation of the SMA driving element through the application of a biasing force, which can be achieved by employing a constant force (such as weight), a linear force (such as elasticity), or by utilizing an opposing SMA element with temperature control [12][13][14][15][16]. The pre-deformation corresponds to the displacement of the actuator's executive unit in a specific direction.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of a Bistable Recuperative Pump Powered by Shape Memory Alloys and a Two-Section Involute Cam

Kostov,

Todorov,

Mitrev

et al. 2023

Actuators

Self Cite

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The paper discusses the synthesis problem of a bistable piston pump, employing a driving mechanism that comprises shape memory alloy wires, a two-section involute cam, and an energy-recuperating spring. The transition from one stable end position to another in the pump is achieved by heating and subsequently shortening one of the shape memory alloy wires, initiating the motion of the mechanism. This is then followed by the engagement of the recuperative spring to traverse the intermediate unstable equilibrium position and complete the entire stroke. The reversal of motion follows a similar approach, where the second SMA wire shortens while the first wire remains in a cold state. Importantly, the mechanism necessitates a low force within the shape memory alloy wire to initiate motion towards the opposite stable position. This research encompasses the examination of type, geometric, and force synthesis considerations for the pump, leading to the development of fundamental kinematic and force relationships. Moreover, a novel mechanism is proposed and synthesized, incorporating a two-section involute cam with a cusp point, to generate the desired discontinuous moment function produced by the recuperative spring. Further analysis reveals that the thermal time constant, which regulates the dynamic response of the mechanism, is directly proportional to the diameter of the driving SMA and inversely proportional to the square root of the number of SMA branches.

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

Cited by 8 publications

References 38 publications

Study of Self-Excited Thermomechanical Oscillator with Shape Memory Alloys

Study of Self-Excited Thermomechanical Oscillator with Shape Memory Alloys

Design development and control of a shape memory alloy linear actuation based XYθ motion stage

Synthesis of a Bistable Recuperative Pump Powered by Shape Memory Alloys and a Two-Section Involute Cam

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