AbstractThe results of an experimental effort to both characterize material damping and enhance structural damping are presented. In order to determine material damping in metallic and fibrous composite materials, a unique facility has been constructed in which transient decay measurements were made in free fall in a vacuum. Specimens were simultaneously excited and lofted with a tuned spring-cocked launcher. Damping data on the free-free mode was obtained by bonding strain gauges to the specimen and connecting them by fine wires to a terminal also in free fall. Graphite/epoxy laminates tested were unidirectional 0°, and ±45° symmetric, under environmental conditions of room temperature and near zero moisture content. Aluminum damping data agrees exactly with previous studies, as to stress and frequency dependence. The material damping in graphite/epoxy was found to be largely independent of frequency and stress level. In order to increase the passive damping level, it is possible to deliberately introduce dry frictional damping into a flexible structure. Experimental measurements of dry friction damping were carried out to investigate the effects of wear, and to correlate with an analytic model of the relative micro-slipping of two surfaces under differential strain and in frictional contact. The friction damping system investigated was a thin-walled aluminum outer tube with a split aluminum or steel inner tube. Dry Coulomb damping occurred at the interface of the inner and outer tube. The outer tube was cycled in compression-compression loading. The friction damping showed considerable correlation with the theoretical model. In order to investigate the effects of wear, the damping systems were cycled one million times. While wear was noticeable, the friction damping was not appreciably affected by the wear after the first few hundred cycles.


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    Titel :

    Experimental measurement of passive material and structural damping for flexible space structures


    Beteiligte:

    Erschienen in:

    Acta Astronautica ; 10 , 5-6 ; 381-393


    Erscheinungsdatum :

    1983-01-06


    Format / Umfang :

    13 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch