Dynamic thermomechanical response of an SMA plate using an all-round shape memory effect and an application to an adaptive fluid-flow controller

This paper describes experimental and numerical results of the transient response of a Shape Memory Alloy (SMA) plate considering thermomechanical coupling and an application of the SMA plate to an adaptive fluid-flow controller. SMA wire has been used as a component of actuators to date. But SMA plates have some advantages over SMA wire, such as larger force generation, shape change and heat generation due to induced current. Therefore, since plates might be used in actuators, especially in microactuators, it is important to evaluate their dynamic response. In this study, the dynamic response caused by the transformation between the R-phase and the parent was evaluated by both numerical analysis and experiment. An SMA plate remembers an arc shape at high temperature and a flat shape at low temperature. Thus, this plate shows an all-round shape transformation, then the transformation kinetics was obtained and finally dynamic response was evaluated. The numerical results of these responses almost agreed with the measured ones. As an application of this SMA plate, we fabricated an adaptive fluid-flow controller. This controller can separate hot fluid and cold fluid, and direct them to their respective outlets by changing the shape of the SMA plate. It continued to operate even after one thousand heat cycles. This SMA actuator can move without sensors and bias springs.