MODELING NONLINEAR RATE-DEPENDENT BEHAVIOR IN FIBER-REINFORCED COMPOSITES

The rate-dependent behavior of AS4/PEEK (APC-2) thermoplastic composit e has been characterized over a wide strain rate range (10x10(-6) to 1 000s(-1)). The low to moderate strain rate experiments were conducted with a servo-hydraulic testing machine, while the high strain rate exp eriments were conducted with a Split Hopkinson Pressure Bar. Two rate- dependent models are introduced to model the material response. Both m odels are developed by using a one-parameter plastic potential functio n to describe the non-linear behavior. Off-axis composite specimens ar e tested in simple tension at different strain rates, and the results are used to determine parameters of these models. Predictions of these models are shown to agree fairly well with the experimental results o ver a wide range of strain rates. (C) 1998 Elsevier Science Ltd. All r ights reserved.