INVESTIGATION OF THE TRANSVERSE PROPERTIES OF A UNIDIRECTIONAL CARBON-EPOXY LAMINATE .1. MATRIX PROPERTIES

The bulk properties of a commercially available high-performance epoxy resin used for continuous-fibre composites have been studied. Fracture toughness and stress/strain properties in tension and compression have been measured. The distribution, of tensile strengths within the resin has been studied by fabricating novel sandwich laminates consisting of a bulk resin core with two outer (0 degrees) glass-fibre-reinforced plastic (GRP) laminates. Sandwich laminates with core thicknesses in the range of 0.6 to 2.4 mm were tested in tension and the individual cracking events in the core were used to construct Weibull strength distribution plots. Weak-link scaling has been applied to correlate the laminate data with the results from the conventional coupon tensile test of the resin. Statistical extrapolation of the data indicates a significant size-effect. Effects of filtration of solid body impurities and inclusions from the resin have also been studied in terms of the resulting modification to the strength distribution.