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Mechanical properties of glasses impacted by debris or micrometeoritesMechanical strength measurements on five glasses and one glass ceramic exposed on the Long Duration Exposure Facility (LDEF) have revealed no damage exceeding experimental limits of error after exposure. The measurement technique subjected less than 5 percent of the sample surface area to stresses above 90 percent of the failure strength. Seven micrometeorite or space debris impacts occurred at locations which were not in that portion of the sample subjected to greater than 90 percent of the applied stress. In consequence of this, the impact events on the sample were not detected in mechanical strength measurements. The physical form and structure of the impact sites was carefully examined to determine the influence of those events upon stress concentration associated with the impact and the resulting mechanical strength influence. The size of the impact site insofar as it determines flaw size for fracture purposes was examined. Surface topography of the impacts reveals that six of the seven sites display impact melting. The classical melt crater structure is surrounded by a zone of fractured glass. Residual stresses arising from shock compression and from cooling of the impact fused zone cannot be included in fracture mechanics analyses based on simple flaw size analyses. Strategies for refining estimates of mechanical strength degradation by impact events are presented.
Document ID
19920018004
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Kinser, Donald L.
(Vanderbilt Univ. Nashville, TN, United States)
Wiedlocher, David E.
(Vanderbilt Univ. Nashville, TN, United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1992
Publication Information
Publication: NASA. Langley Research Center, Second LDEF Post-Retrieval Symposium Abstracts
Subject Category
Nonmetallic Materials
Accession Number
92N27247
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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