An Experimental Study to Determine the Reduction in Ultimate Bending Moment of a Composite Plate due to an Internal Delamination.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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The purpose of this study was to determine experimentally the effects of internal delaminations in a graphite-epoxy composite plate on the plates ultimate bending moment. The experiments were conducted using 4-inch by 7-inch specimens with a balanced 0, or - 45, 90, 8-ply layup. The delaminations were created by inserting a thin teflon disc between two lamina during layup preparation. The location of the disc, i.e. delamination, was varied in each test, and two disc sizes were considered. The test results revealed that delaminations located near an outer surface resulted in a greater reduction in the ultimate moment than those located near the center of the layup. Furthermore, the reduction in ultimate bending moment was found to be independent of the disc size. The tendency for the internal delaminations to propagate at relatively low load levels was observed and recorded. Author