Compression Fatigue Behavior of Graphite/Epoxy in the Presence of Stress Raisers

摘要: Graphite/epoxy composites are being applied to aircraft structures because of their demonstrated capability reduce weight and increase life. Although have better fatigue properties than metals, behavior differs significantly. Unlike exhibit excellent tensile behavior-the constant amplitude strength at 10 7 cycles close static ultimate. Compression reversed loading in the presence stress raisers, however, has not been well characterized. This program was therefore undertaken determine characteristics under these conditions. Two raisers were considered; first an open hole second damage resulting from low velocity, hard object impact. For specimen, variable tests performed significance compression investigate failure mechanism. These indicated that life is less for tension-tension will be important design consideration future composite applications. The mechanism appeared local progressive matrix near raiser delamination, final by fiber buckling. variable-amplitude results also unconservativeness Miner's rule making analytical predictions. In order nature impact generic structural elements, velocity residual conducted on solid laminate specimens 42 48 plies thick honeycomb sandwich with 12-ply face sheets. Results post indicate subvisual can degrade strength, although propagate moderate (0.003) cyclic strain.