Failure analysis of a fiberglass-reinforced plastic pressure vessel
- Sandia National Labs., Albuquerque, NM (United States); and others
A fiberglass-reinforced plastic (FRP) pressure vessel containing sulfuric acid failed catastrophically in service. Preliminary investigations ruled out failure due to sabotage and chemical or mechanical overpressure. Subsequent examination of the fiber fracture surfaces and measurements of mirror radii indicated that fibers failed at stresses significantly below their expected strength. Further examination by scanning electron microscopy and energy dispersive spectroscopy suggested that the glass fibers had been exposed to sulfuric acid, a reagent that corrodes this type of glass and degrades it strength. Finite element analysis predicted axial stresses in the vessel in an exposed region above a supporting steel cradle, that exceeded the fiber-matrix strength of the circular wrap layers of FRP material. Numerous cracks were detected in this region using a vicinal illumination technique. We concluded that vessel failure was due to cracking of the circular wraps under high axial stresses, followed by exposure of the fibers in the cross ply layers to trapped acid, which produced significant strength degradation of these fibers. Progressive rupture of the cross ply fibers, starting at the outer surface of the FRP and extending inwards and laterally, occurred until a crack of critical size was produced.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 535644
- Report Number(s):
- CONF-950739--
- Country of Publication:
- United States
- Language:
- English
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