MODELING CREEP IN THERMOPLASTIC COMPOSITES

A creep model for unidirectionally reinforced fiber composites was developed based on a one-parameter potential function. The same potential function was used to describe plastic flow and time-dependent creep deformation. The material constants in the model were determined by using the uniaxial tension test of off-axis coupon specimens. In terms of effective stress and effective creep strain, the anisotropic creep behavior can be given by a stress-dependent master creep curve irrespective of loading direction relative to fiber orientation. DuPont's AS4/PEKK thermoplastic composites were used in the creep experiment. Results for both unidirectional and laminated composites were presented.