ABSTRACT
Sensor arrays o f this type have been suggested as candidate systems for detection o f impact damage in composite aircraft structures [5]. Carbon fibre composites are susceptible to impact events and barely visible impact damage is a cause of concern as the compression after impact strength can be greatly reduced [6]. Smart structures offer the possibility o f monitoring potentially damaging events and indicating if the performance o f the composite has been reduced [7]. In performance o f this function, the sensing capability needs to be o f adequate sensitivity and bandwidth, and both sensor and fibre need to be of sufficient strength to resist both service loading and external mechanical damage. Previous experiments on optical fibres embedded in composites have demonstrated that they can resist imposed strains at least up to the failure strains o f the carbon fibre [5]. Fatigue strength o f composites containing optic fibre has similarly been demonstrated to be equivalent to samples without the optical fibre. However, where the optical fibre is orientated perpendicular to the surrounding fibres a large resin area is formed and the surrounding area is crimped. This artefact could degrade the compression strength [8].
