Prediction of creep and creep rupture of uni-directional carbon fiber reinforced polymer composite and its epoxy matrix. Part 1: Creep

A model, incorporating ``Thermal Activation Theory,`` is presented to model and predict reliably, the creep and creep rupture of uni-directionally reinforced [62% volume fraction] continuous carbon fiber composite [AS4/3501-6] and its epoxy matrix. In part 1 of this series, simulated creep results are compared with the experimental results at various stress levels in the temperature range 295--433 K [T{sub g}, of the matrix is 512 K], for AS4/3501-6 [90]{sub 16} composite as well as pure epoxy matrix. The activation energy derived, by analyzing creep and constant strain rate test results, agrees with the experimental value measured by DMTA tests and corresponds to the {alpha} transition in the epoxy matrix. However, the T{sub g} of the matrix is found to be increased by 6 K to 518 K by the reinforcing fibers while the rubbery modulus is increased by a factor of 28. It is concluded that the effect of reinforcing fibers is not to alter the creep mechanism but the creep behavior of the matrix by increasing the resistance to cooperative segmental mobility.