Monitoring bending fatigue in carbon-fibre/epoxy composite strands: a comparison between mechanical and resistance techniques

The bending fatigue behaviour of unidirectional carbon-fibre/epoxy composite strands was monitored by the changes in resistivity and in bending modulus. The fibres were PAN-based carbon fibres and the matrix was a bisphenol-A-based epoxy resin. A load cell connected to one jaw of the test assembly was used to monitor the resulting bending moment. Simultaneously the voltage, at constant current, along the longitudinal axis of the strand was measured, and a correlation between the increase in resistivity and the decrease in bending modulus was seen.