Deformation and Rotary Driving Characteristics of a Shape-Memory Alloy Thin Strip Element

Abstract

If a shape-memory alloy (SMA) thin strip is applied to elements subjected to torsion, a rotary driving element with a simple mechanism can be developed. With this purpose in view, torsion, recovery torque and torsion fatigue tests were carried out for a TiNi SMA thin strip, and the basic torsion characteristics of the strip were obtained. It was found that torque and recovery torque both increase in proportion to the angle of twist and temperature, and that the recoverable strain energy increases in proportion to temperature, while dissipated work decreases slightly with an increase in temperature. Fatigue life decreases in proportion to the angle of twist, and the fatigue life of a heat-treated material is longer than that of an as-received material. The angle of twist at the fatigue limit for the heat-treated material is almost the same as for the as-received material. As a practical application for a rotary driving element of this type, a means of opening and closing a door with an element driven by an SMA thin strip is demonstrated.

A Review of SMA-Based Actuators for Bidirectional Rotational Motion: Application to Origami Robots

“…Consequently, the fabrication and assembly process can be simplified. Different designs of elementary torsional actuators can be found in literature, rotary actuation capability are experimentally proven using torsional strips (Tobushi et al, 2008;Tobushi et al, 2010;Tobushi et al, 2013), torsional bands (Shim et al, 2015), torsional wires (Kim J. et al, 2015) and torsional tubes (Benafan et al, 2019). Besides the shear-strain-drivenactuators, investigations on torsional coil spring (Salerno et al, 2013;Sheng and Desai, 2015;Sheng et al, 2017) that convert the local normal strain to global shear strain are carried out and results show an improvement of motion range and reduction of output torque compared to the wire form torsional actuator.…”

An experimentally-driven approach to model bending in a thermally activated SMA-based beam

“…The active element usually works in the so-called controlled recovery condition since the SMA material is partially restrained from recovering its original shape [3,4]. Depending upon the actuation mode required for the intended application, SMA active elements can be in the form of helical springs [5][6][7][8], wires [9][10][11], rods [12][13][14], strips [15][16][17][18], sheets or ribbons [19]. Due to the large amount of force and displacement produced on heating, SMAs are used for sensing, actuation or self-healing purposes [3,20] in different branches of engineering including aerospace devices [21][22][23], civil structures [24,25] and biomedical applications [26][27][28].…”

A smart soft actuator using a single shape memory alloy for twisting actuation

“…Gabriel et al (1988) made a twisting actuator using a thin SMA rod which is fixed at both ends after applying a torsional prestrain. Tobushi et al (2009) made a door hinge that can open and close using a thin SMA strip with anapplied torsional prestrain. Jardine et al (1996) proposed a twisting wing using anSMA TiNi torque tube with anapplied torsional strain.…”