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Proceedings Paper

Fiber Optic Strain Measurements In Filament-Wound Graphite-Epoxy Tubes Containing Embedded Fibers
Author(s): R. S. Rogowski; J. S. Heyman; M. S. Holben Jr.; C. Egalon; D. W. Dehart; T. Doederlein; J. Koury
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Paper Abstract

Several planned United States Air Force (USAF) and National Aeronautics and Space Administration (NASA) space systems such as Space Based Radar (SBR), Space Based Laser (SBL), and Space Station, pose serious vibration and control issues. Their low system mass combined with their large size, precision pointing/shape control and rapid retargetting requirements, will result in an unprecedented degree of interaction between the system controller and the modes of vibration of the structure. The resulting structural vibrations and/or those caused by foreign objects impacting the space structure could seriously degrade system performance, making it virtually impossible for passive structural systems to perform their missions. Therefore an active vibration control system which will sense these natural and spurious vibrations, evaluate them and dampen them out is required. This active vibration control system must be impervious to the space environment and electromagnetic interference, have very low weight, and in essence become part of the structure itself. The concept of smart structures meets these criteria. Smart structures is defined as the embedment of sensors, actuators, and possibly microprocessors in the material which forms the structure, a concept that is particularly applicable to advanced composites. These sensors, actuators, and microprocessors will work interactively to sense, evaluate, and dampen those vibrations which pose a threat to large flexible space systems (LSS). The sensors will also be capable of sensing any degradation to the structure. The Air Force Astronautics Laboratory (AFAL) has been working in the area of dynamics and control of LSS for the past five years. Several programs involving both contractual and in-house efforts to develop sensors and actuators for controlling LSS have been initiated. Presently the AFAL is developing a large scale laboratory which will have the capacity of performing large angle retargetting manuevers and vibration analysis on LSS. Advanced composite materials have been fabricated for the last seven years, consisting mostly of rocket components such as: nozzles, payload shrouds, exit cones, and nose cones. Recently, however, AFAL has been fabricating composite components such as trusses, tubes and flat panels for space applications. Research on fiber optic sensors at NASA Langley Research Center (NASA LaRC) dates back to 1979. Recently an optical phase locked loop (OPLL) has been developed that can be used to make strain and temperature measurements. Static and dynamic strain measurements have been demonstrated using this device.' To address future space requirements, AFAL and NASA have initiated a program to design, fabricate, and experimentally test composite struts and panels with embedded sensors, actuators, and microprocessors that can be used to control vibration and motion in space structures.

Paper Details

Date Published: 16 January 1989
PDF: 6 pages
Proc. SPIE 0986, Fiber Optic Smart Structures and Skins, (16 January 1989); doi: 10.1117/12.948904
Show Author Affiliations
R. S. Rogowski, NASA Langley Research Center (United States)
J. S. Heyman, NASA Langley Research Center (United States)
M. S. Holben Jr., NASA Langley Research Center (United States)
C. Egalon, NASA Langley Research Center (United States)
D. W. Dehart, Air Force Astronautics Laboratory (United States)
T. Doederlein, Air Force Astronautics Laboratory (United States)
J. Koury, Air Force Astronautics Laboratory (United States)

Published in SPIE Proceedings Vol. 0986:
Fiber Optic Smart Structures and Skins
Eric Udd, Editor(s)

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