Torsional Deformation and Fatigue Properties of TiNi SMA Thin Strip For Rotary Driving Element

Abstract

In order to develop the rotary driving element with SMA thin strip, the torsional deformation and fatigue properties of a TiNi SMA thin strip were investigated. The results obtained are summarized as follows. (1) In the SMA thin strip subjected to torsion, the MT appears along the edge of the strip due to elongation of the edge of the strip and grows to the central part. (2) The number of cycles to failure decreases with an increase in the maximum angle of twist in torsion fatigue. The fatigue life in pulsating torsion is longer than that in alternating torsion by five times. The fatigue limit exists in a certain value of disspated work of the strip in each cycle. (3) Based on the two-way motion of a lifting model by using two kinds of SMA thin strip, it is confirmed that the two-way driving element with a small and simple mechanism can be developed by using the SMA thin strips.