The effect of fibre volume fraction on damage initiation and propagation of woven carbon-epoxy multi-layer composites

In the current study, the mechanical behaviour, damage initiation and propagation properties of 2 x 2-twill woven carbon composites with various fibre volume fractions, under uni-axial tension in the warp direction, were investigated. Observations of damage were made using acoustic emission (AE), x-ray and microscopy techniques. The mechanical properties and strain values of the composite damage thresholds were determined. The strain levels at which AE events were recorded for the first time (i.e. the epsilon(min) values) were affected by variations in fibre volume fraction; however, characteristic strain values indicating damage initiation (i.e. epsilon(1) and epsilon(2)) were not affected by variations in fibre volume fraction.