Creep behavior of carbon fiber/epoxy matrix composites

The creep behavior of a carbon fiber/epoxy matrix composite was studied through tensile and flexural creep testing. No creep rupture failures were observed in short-term (less than 1600 h) room temperature tensile creep tests at loads up to 77% ultimate tensile strength (UTS). For elevated temperature flexural creep compliance data taken at isotherms between 30 and 75 °C, the principle of time–temperature superposition held. Master curves were generated by shifting the data by hand and also using the constant activation energy of the glass transition relaxation to estimate the shift factors. It was shown that the constant activation energy assumption worked fairly well, but only for temperatures below the onset Tg of the material. Predictions were made concerning the creep levels at the end of a proposed 50-year design life.