Characterization and design of antagonistic shape memory alloy actuators

Abstract

Antagonistic shape memory actuators use opposing shape memory alloy (SMA) elements to create devices capable of producing differential motion paths and two-way mechanical work in a very efficient manner. There is no requirement for additional bias elements to ‘re-arm’ the actuators and allow repetitive actuation. The work generation potential of antagonistic shape memory actuators is determined by specific SMA element characteristics and their assembly conditions. In this study, the selected SMA wires are assembled in antagonistic configuration and characterized using a dedicated test bench to evaluate their stress–strain characteristics as a function of the number of cycles. Using these functional characteristics, a so-called ‘working envelope’ is built to assist in the design of such an actuator. Finally, the test bench is used to simulate a real application of an antagonistic actuator (case study).

Explorative study on adaptive facades with superelastic antagonistic actuation

“…Most of the actuated structures using SMA elements are based in thermally driven one‐way shape‐memory based actuators, which have to rely on bias force‐creating components in order to restore their initial shape, since they do not recover their original configuration upon cooling. One of the methods to provide the bias force, obtaining reversible‐actuation systems, is to use an antagonistic type of actuation, inspired by muscles that work in pairs . An antagonistic actuation requires the assembly of two opposing SMA active elements in which the contraction (upon heating) of one prestressed actuator causes the opposing actuator to stretch, arming it to a subsequent heating.…”

“…One of the methods to provide the bias force, obtaining reversible-actuation systems, is to use an antagonistic type of actuation, inspired by muscles that work in pairs. [7][8][9][10][11][12][13] An antagonistic actuation requires the assembly of two opposing SMA active elements in which the contraction (upon heating) of one prestressed actuator causes the opposing actuator to stretch, arming it to a subsequent heating. One of the main advantages of these antagonistic devices is the fact that they not need continuous power, but just an electric pulse, to switch permanently to a new configuration.…”

Development of a new mechanism to change velocity in helical swimmer robot at low Reynolds Number

“…A type of Ti-Ni SMA has been selected for the helical tail of this swimmer, which is an important type of SMA with many advantages including noiseless actuation, large deformation, large recovery strain (< 6%), high biocompatibility, and low actuation voltage [28]. Table 3 indicates the main properties of the SMA spring [29]. In order to obtain an extreme forward velocity, the minimum and maximum values of desired helical length are chosen based on the veri ed results in Section 3.…”

Model of Torque in Disc-Type Magnetorheological Brake Driven by Shape Memory Alloy

“…SMAs may undergo mechanical shape changes at relatively low temperatures and retain them until heated, then coming back to the initial shape [9]. This makes SMAs unique compared to other smart materials that can be used for actuator applications [10].…”