Effects of Prior Aging at 288 C in Argon Environment on Creep Response of Carbon Fiber Reinforced Pmr-15 Composite with 45 Fiber Orientation at 288 C

The creep and recovery response of carbon fiber reinforced PMR-15 composite with a 45 fiber orientation was examined in an argon environment at 288 C. Mechanical testing was executed for unaged specimens as well as specimens aged up to 1000 hours. Tensile tests were performed to determine Young's modulus of elasticity and ultimate tensile strength. The creep tests were carried out at stress levels of 30 and 60 MPa. Creep periods of 25 hours were followed by recovery periods of 50 hours at zero stress. Weight loss measurements as a function of aging time were taken as well. The accumulated creep strain of the unaged specimen was ~.72% at 30 Mpa and ~1.86% at 60 MPa. The accumulated creep strain of the 1000 h aged test specimen was ~.15% at 30 MPa and ~.72% at 60 MPa. Prior aging time reduced the amount of creep strain accumulation, but it did not significantly affect recovery. The carbon fiber reinforced PMR-15 composite had a weight loss of ~1.37% after 500 hours of aging, compared to a weight loss of ~.91% at 250 hours. The specimens experienced an initially rapid weight loss followed by a period of steady increase in weight loss rate.