Investigation of non-contact bearing systems based on ultrasonic levitation

Su ZhaoPaderborn, Univ., Diss., 201

Defense Technical Information Center thesaurus

This DTIC Thesaurus provides a basic multidisciplinary subject term vocabulary used by DTIC to index and retrieve scientific and technical information from its various data bases and to aid DTIC`s users in their information storage and retrieval operations. It includes an alphabetical posting term display, a hierarchy display, and a Keywork Out of Context (KWOC) display

Aeronautical Engineering: A continuing bibliography with indexes (supplement 182)

This bibliography lists 475 reports, articles and other documents introduced into the NASA scientific and technical information system in December 1984

Miniaturized Thin-Film Piezoelectric Traveling Wave Ultrasonic Motor

For many small-scale systems, compact rotary actuators are highly attractive. Many current millimeter-scale motor technologies, such as electrostatic motors and electromagnetic motors, operate at high speeds (on the order of 105 RPM) but low torque, usually pico- or nano-newton-meters. In order to drive large loads at speeds closer to 100 to 1000 RPM, gearing would be required, which drastically increases system complexity and size. Electromagnetic motors, which are effective at the macro-scale, become less practical at the millimeter-scale due to unfavorable scaling of energy density and complex fabrication. Electrostatic micro-motors require approximately 100 V for operation and produce limited torque. Traveling wave ultrasonic motors (TWUM) can provide micro- to milli-newton-meters of torque at low speeds and fill a necessary place within the millimeter-scale rotary motor landscape. Using recent developments in high quality piezoelectric film deposition and microfabrication techniques, TWUM can be made an order of magnitude smaller than currently possible. The fabrication process for the TWUM is described within, with a focus on stator fabrication and the enabling fabrication methods developed for the manufacture of TWUM, including backside vapor-HF release, deep reactive ion etch footing release, and photoresist deep-trench refill. Design and characterization of the traveling wave stator component, both disc and ring are described. Disc stators, 1 to 3 mm in diameter, exhibited traveling waves up to 1 μm in out-of-plane amplitude with quality factors in air of 95. The design process for ring stators with mechanical impedance transformer tethers is presented. The tethers are designed to allow large motion at the stator perimeter, while tethering the stator to the anchored substrate. This mechanical impedance transformer tether allowed for an in increase in standing wave amplitude by over 100% compared to straight tethers. TWUM were demonstrated and characterized, and represent the smallest TWUM currently reported, at 2 to 3 mm in diameter and less than 1 mm thick. Motor performance characteristics are presented, with speeds exceeding 2000 RPM while consuming 4 mW of power at 10 V. These millimeter-scale motors have potential applications in fields such as fuzing, medical imaging, micro-robotics, and sensor steering and calibration

Cumulative index to NASA Tech Briefs, 1963-1967

Cumulative index to NASA survey on technology utilization of aerospace research outpu

Advances in Vibration Analysis Research

Vibrations are extremely important in all areas of human activities, for all sciences, technologies and industrial applications. Sometimes these Vibrations are useful but other times they are undesirable. In any case, understanding and analysis of vibrations are crucial. This book reports on the state of the art research and development findings on this very broad matter through 22 original and innovative research studies exhibiting various investigation directions. The present book is a result of contributions of experts from international scientific community working in different aspects of vibration analysis. The text is addressed not only to researchers, but also to professional engineers, students and other experts in a variety of disciplines, both academic and industrial seeking to gain a better understanding of what has been done in the field recently, and what kind of open problems are in this area