Effect of Prior Aging on Fatigue Behavior of IM7/BMI 5250-4 Composite at 191-C

IM7/BMI 5250-4 with carbon fiber orientations and [0/90] were aged in air at 191-C for up to 1000 hours. The weight loss was analyzed during the aging process. Tension to failure tests were performed on both the unaged and aged specimens to establish a baseline for the Ultimate Tensile Strengths and Young's Modulus. Tension-tension cyclic load fatigue testing was conducted on the specimen to determine the effect of prior aging on the fatigue response of the composite. Cyclic strain accumulation was not influenced by prior aging, but it was influenced by the stress levels applied. Specimens lost 0.2% more weight than the [0/90] specimens from aging in air.