Survivability of Affordable Aircraft Composite Structures. Volume 3: Characterization of Affordable Woven Carbon/Epoxy Composites Under Low-Velocity Impact Loading

摘要

Experimental investigations carried out on affordable woven carbon/ epoxy laminates under low-velocity impact loading are reported in this volume. Stitched and unstitched carbon/epoxy laminates were fabricated using plain and satin weave fabric with SC-15 epoxy resin system. Two orthogonal stitch spacing: 12.7- and 15.4-mm were used. Four-inch square samples were subjected to low- velocity impact loading at energy ranging from 5-40 J. Results of the study indicated that the damage due to low-velocity impact loading reduced considerably due to stitching. Of the two weave types, satin weave laminates carried higher impact loads compared to plain weave laminates due to relatively straighter fiber architecture. In another study, effects of laminate thickness and samples size on the upper and lower-bound energy level were established. To establish damage tolerance of woven fabric composites, post impact studies were carried out which included static compression and fatigue tests. Post fatigue tension tests were carried out to determine the reduction in stiffness. Though most of the laminates sustained 100,000 fatigue cycles, there was a sharp decrease in the stiffness with increasing drop height.