No abstract

No abstract

Abstract. The main drawbacks of SMA actuators are a slow response and a waste of electric power. The power should be continuously supplied for SMA elements to remain austenite state until the actuator begins to take the other position. The problems are more serious when batteries and thick SMA elements are used. We propose a new SMA actuator which consumes little energy and responds very quickly. The actuator consists of a specially designed bias spring and two SMA elements which exert the force in opposite direction to each other. The bias spring, unlike a common spring which has one stable position, has two stable positions. A SMA1, for instance, contracts on heating by electricity, the actuator takes one stable configuration. No further power supply is necessary to maintain the stable position, providing enough time for the SMA1 to cool. When the other SMA2 is heated, it contracts with enough force to move the bias spring and to expand the already-cooled SMA1. Power supply stops immediately after the actuator takes the other stable configuration, causing power saving and quick response.

There has been no doubt that a closed coil can not be further compressed. We found out that compression of a closed coil is achieved by reversing coil orientation and subsequently extending the coil. The new technology makes many applications of coil springs feasible that have been regarded as impossibility. Control and generation of two way shape memory effect (twsme) of shape memory alloys are taken here as examples.