A study on disc spring actuator made from Ti-Ni shape memory alloy

Abstract

With recent developments in the technology of intelligent materials, including shape memory alloys that deform autonomously depending on changes in the environment, such as temperature, it is expected that next-generation actuators that are simple, lightweight, and compact will also be developed. Consequently, in this paper, we investigated the disc spring type actuator made of Ti-Ni shape memory alloy (SMA), which is more compact than the conventional SMA coil spring type actuator. Firstly, prototype SMA disc springs were made from a thin SMA plate by metal stamping and shape-memory treatment. Secondly, we measured load-displacement curve of this prototype at both high and low temperatures. Thirdly, from the experimental results, the difference between displacements at low and high temperatures was used to estimate the performance (output displacement) of the SMA disc spring. The observations revealed that output displacement rate of the SMA disc spring was greater than 50% when the load was 30N. Compared to the coil spring, a similar effect would be obtained in approximately 37% of the space by the SMA disc spring. Finally, we conducted a finite element analysis of the SMA disc spring using a non-linear finite element analysis program, LS-DYNA. The validity of the analysis procedure was confirmed by comparing the analysis results with the experimental results.