Influence of Environmental Cycling on the Mechanical Properties of Composite Materials

Abstract

Static and fatigue tests were carried out on CFRP specimens exposed to environmental conditions with the purpose of simulating the real environ mental conditions for today's aircraft. The investigation has comprised ± 45° reinforced test specimens, 24 mm wide and 1 mm thick, built up from carbon-fiber prepreg THORNELL 300/NARMCO 5208. In the investigation polyurethane-covered specimens were also tested, in order to investigate the protecting ability of that mate rial. The results show clear deteriorations in both static and fatigue proper ties due to environmental exposure. The material becomes more ductile under the influence of moisture, and after prolonged exposure one can notice a debonding effect between the fibers and the matrix. Environ mental degradation becomes more pronounced if the specimens are pre loaded prior to exposure.