The Influence of Environmental Conditions on the Vibration Characteristics of Chopped- Fiber-Reinforced Composite Materials

The effects of exposure to elevated temperatures and common auto motive fluids on the dynamic stiffness and internal damping of several E-glass/polyester automotive composite materials have been measured. A previously developed forced flexural vibration technique was modified to suit the requirements of the environmental conditions. Stiffness and damping of three chopped-fiber-reinforced composites and of two hybrid chopped/continuous-fiber-reinforced composites were measured over the temperature range 20° - 120°C and during 1000 hour soaking tests in distilled water, salt water, motor oil, gasoline, and anti-freeze solutions. Correlations between types (and amounts) of environmental exposure and corresponding changes in dynamic properties are discussed.