Effect of Temperature on Fatigue Response of Surface-Notched [(0/ ± 45/0) ] Graphite/Epoxy Laminate
SourceThe fatigue behavior of surface-notched [(0/± 45/0)s]3 T300/5208 graphite-epoxy specimens was studied over the temperature range from room temperature to 421 °F (216 °C). The specimens, after being subjected to two lifetimes of a 135 000-cycle tension-dominated flight-by-flight spectrum, were nondestructively inspected (using tetrabromoethane-enhanced X-ray radiography and C-scanning) and then tested at room temperature to determine their residual strengths. The test results show that both the extent of matrix damage and residual strengths increase with fatigue test temperature. If the fatigue-induced matrix damage region (FIMDR) is the same size or smaller than the delamination region observed prior to static failure, then the residual and static strengths are equal. If the FIMDR is larger than the delamination prior to static failure, then the residual strength is higher than the static strength. Finally, the residual strength is less than the net section strength.