Showing papers by "James E. Hubbard published in 2007"

Description and characterization of an electroactive polymer synthetic jet actuator

Abstract: The objective of this research was to describe and characterize the performance of an innovative new method of actuating a synthetic jet. This particular method utilizes a pre-strained dielectric elastomer membrane excited to operate at resonance. The paper describes the mechanism by which the actuator operates, the experimental techniques used to characterize it and discusses the results of the characterization. A series of experiments were devised to capture the influence of specific device parameters on the actuator system performance. The device parameters considered were: chamber volume, orifice diameter, orifice length, electrode area, excitation frequency, and excitation amplitude. Six metrics were collected for each of the tests: membrane displacement, chamber pressure, exit velocity, auditory signal, supply voltage, and supply current. Based on the cases tested, peak attainable orifice velocity was experimentally determined to be approximately 17 m/s, though the authors believe this can be significantly increased. Basic system design guidelines were also determined, and directions for future work have been identified.

A computational method for materials selection in a hybrid actuation system

Abstract: Researchers at NASA-LaRC have developed a hybrid actuation system (HYBAS) that cooperatively employs an electroactive polymer and an electrostrictive single crystal. Experimental measurements and theoretical model predictions have been in good agreement thus far. To date, current research has only explored the usage of one electroactive polymer and one electrostrictive single crystal. A computational model was created based on this theoretical model. It implements the equations necessary to predict the actuator displacement profile and maximum displacement. Among the model variables are the actuator material properties. Changing the actuator materials has notable effects on actuator performance. As many viable materials as could be found were compiled into a database which can serve as a building block upon which a larger database can be built. Using these materials, a trade study was performed to determine which combination of materials demonstrates the best performance. As more electroactive materials are compiled, more extensive trade studies can be performed. Thus, the work in this paper will serve as a guideline for future HYBAS designs.