Stress corrosion of aligned glass fibre-polyester composite material

Abstract

The main features of the stress-corrosion failure of glass-reinforced plastic tanks and vessels are described. Model experiments using a modified double cantilever beam test have been made on aligned composite materials tested in 0·6M HCI. The rate of crack growth normal to the fibre direction depends on stress intensity. The crack-tip fracture processes for cracks growing in the velocity range 10⁻⁹ to 2 × 10⁻⁸ m S^−l have been determined using fractographic techniques. The stresses in the fibres before fracture at the crack tip have been estimated from the size of the mirror zones. A major feature of stress corrosion is the planar nature of the crack surface and, at low stress intensities, fracture occurs without interface cracking or debonding. An estimate of the strain energy release rate has been made from an analysis of the stress fields at the crack tip and the mechanisms of crack growth. The results are in reasonably good agreement with experimentally determined values.

MST/64