ABSTRACT

Actuation materials are an essential component of mechanisms that can operate in extreme environments. Because they are embedded in the mechanism, there are a variety of mechanical and electrical interfaces that need to be considered when designing mechanisms that can withstand and operate at extreme temperatures to ensure that the system operates as intended. It is not enough to prove that the actuator material at the component level will operate effectively at elevated temperatures. There could also be combined effects that need to be addressed such as high-pressure and high-radiation environments. Also, an environment that is benign at room temperature may become highly reactive to materials in the actuator or mechanism at high temperature. Electrical properties, such as conductivity for conductors and the resistivity for insulators, need to be evaluated over the whole range of operational temperatures. In many applications the temperature might be cycled so one needs to thermally cycle the actuator to ensure that the increase and decrease in temperatures does not produce a critical stress causing a fracture, rupture, de-poling, de-lamination or a critical change of friction within the device. All of the same issues that can affect the life of the actuator must also be considered when designing the mechanism. Although we have concentrated our investigation in the actuation, one needs to also invest in appropriate gearing and rotary and linear bearings in order to produce efficient actuators.