Mohammad K. Hossain

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

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, T g (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.

Environment-Assisted Cracking of Structural Materials under Different Loading Conditions

Abstract Significant efforts are ongoing, nationally and internationally, to reduce the radioactivity of spent nuclear fuel (SNF) and high-level waste (HLW) for their disposal in a potential reposi...

Cracking of martensitic alloy EP-823 under controlled potential

The susceptibility of martensitic Alloy EP-823 to stress corrosion cracking was evaluated with and without an applied cathodic potential using the slow-strain-rate (SSR) testing technique. The magnitude of the applied potential was based on the corrosion potential determined by cyclic polarization. The cracking susceptibility in an acidic environment at different temperatures was expressed in terms of the true failure stress (σf), time to failure (TTF), and ductility parameters, including percent elongation (%El) and percent reduction in area (%RA). The data indicate that the magnitudes of σf, TTF, %El, and %RA were reduced due to cathodic charging. The scanning electron microscopic evaluations of the primary fracture surface of the specimens used in SSR testing revealed a combination of ductile and brittle failures. Further, the secondary cracks at the gauge section of these specimens were characterized by branching.