Nonlinear constitutive equation for temperature degraded unidirectional carbon fiber reinforced epoxy

In this study, unidirectional carbon fiber reinforced epoxy was made by vacuum-assisted resin transfer molding (VARTM). Accelerated tests have been conducted on resulting composites at different temperature and different time. Flexural tests results show that modulus and strength decreased with increasing of time and temperature. Based on the experimental result, a linear damage model has been combined with the Weibull distribution function to establish a constitutive equation for carbon/epoxy composite. The parameters in this model are the modulus E, the Weibull shape parameter and Weibull scale parameter. The simulated stress-strain curves from the model are in good agreement with the test data. All three parameters were found to be temperature and time dependent.