MODELING THE VISCOPLASTIC BEHAVIOR OF FIBER-REINFORCED THERMOPLASTIC MATRIX COMPOSITES AT ELEVATED-TEMPERATURES

An investigation was performed to study the mechanical response of fiber-reinforced thermoplastic matrix composites at elevated temperatures. The primary concern of the study was the effect of temperature on the viscoplastic behavior of the composites. During the investigation, an analytical model was developed for analyzing the response of both unidirectional and multidirectional composities at elevated temperatures. The model considers that the fibers have a linearly elastic behavior but the matrix responds viscoplastically with temperature. Micromechanics theories were adopted and developed to integrate fibers and matrix properties for predicting the response of unidirectional composities. Numerical algorithms were developed based on the lamination theory for evaluating the response of the laminated composities. Based on the model, a computer code was also developed for calculating the mechanical response of thermoplastic matrix composites subjected to both thermal and mechanical loading. In order to verify the model, experiments were also conducted for multidirectional APC-2 carbon/PEEK fiber composites and fairly good agreements were found between the predictions and the data.