Volume 7, Issue 4 (April 2010)
Creep-Fatigue Relationships in Electroactive Polymer Systems and Predicted Effects in an Actuator Design
The paper concerns the time-dependent behavior of electroactive polymers (EAPs) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of EAPs is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under cyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the National Aeronautics and Space Administration Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.