Effects of Moisture and Temperature on High Strain Rate Behavior of S2-Glass–Vinyl Ester Woven Composites

Abstract

The effects of moisture and temperature on high strain rate responses of S2-glass–vinyl ester woven composites have been studied in this work. Compressive properties and micro-structural damage progression under high strain rate loading have been investigated using the Split Hopkinson Pressure Bar technique. The compressive stress pulse is applied through the thickness direction (TD) as well as through the filler direction. The stress strain responses at strain rates ranging 490–1470s−1 under various environmental conditions have been investigated and the relevant failure modes have also been identified by optical and scanning electron microscopic examinations. The results indicate that moisture and temperature degrade the compressive failure strength under high strain rate loading. The level of such degradation is seen to vary with strain rates and loading direction. In general, the failure strength and failure strain of both dry and wet samples are seen to be increased under high strain rate loading. The strain rate sensitivity of the woven composites is more significant if the failure is dominated by the resin materials. High temperature tests were conducted at temperatures ranging 23–204°C. The maximum rate effect is observed below the glass transition temperature, Tg (121°C) specifically for TD specimens. Microbuckling of the fiber, kinking and fiber splitting are the major failure modes for the specimens loaded in filler direction. The specimens loaded in the thickness direction mostly failed under matrix cracking.