Strength Degradation of Aramid-Fiber/Epoxy Composites

摘要

The moisture absorption kinetics for Kevlar 49 epoxy have been measured for four environmental conditions. The strength degradation for the composite has been systematically measured by six experiments for each of the four states. The tensor polynomial strength coefficients are generalized to represent the strength degradation for the moisture absorbed states. Due to the big difference between tensile and compressive strength for Kevlar 49 composites, analytical representation of the failure surface requires a third-order tensor polynomial. Four additional biaxial experiments are needed to provide the necessary data. The degree of fiber-controlled strength degradation is different from the degradation of matrix-controlled strength, which causes the failure surface to shift and deform. This shift should also be characterized by a third-order tensor polynomial. (Author)