Evaluation of the Fiber/Matrix Interfacial Properties under Static and Fatigue Loading using Model Composites

Abstract

Single fiber pull-out tests under static and fatigue loading were carried out to investigate the influence of wet environment on the interfacial strength and on the propagation properties of interfacial debonding of an aramid/epoxy system using the specially designed model composites. The fiber/matrix interfacial strength was decreased by 26% after 7 week immersion in deionized water at 80℃. In dry air, interfacial debonding under fatigue loading propagated faster than in laboratory air, whereas it hardly propagated in wet air. When the length of interfacial debonding became longer, the fatigue propagation rate of interfacial debonding slowed down and retarded irrespective of the environment although a constant fatigue load was applied to the sample. This behavior was considered to be owing to the friction stress on the debonded wakes.