Characterisation of intrinsically healing fibre-reinforced polymer composites: an acousto-ultrasonic approach

The poor interlaminar properties of the fibre-reinforced polymer (FRP) composites limit their structural applications. One of the novel ways to mitigate this problem is the incorporation of intrinsic healing capability into the FRPs. In this research work, the intrinsic healing capability of two configurations of carbon FRPs (CFRPs) is characterised under 3-point bending tests. The mechanical test results show that one of the CFRP configurations, the unidirectional (UD200) CFRP, is able to significantly recover the flexural properties. The other configuration, twill-weave (TW415) did not recover the flexural properties as efficiently as the UD200. Nevertheless, it is still able to mitigate severe failure modes after healing. To monitor the healing process non-destructively, a stress wave-based analysis, the acousto-ultrasonic (AU) approach is used. A novel risetime parameter RT_f is developed to analyse the stress wave signals. The results show that RT_f is able to monitor the healing process efficiently. The final results demonstrated the capability of the novel destructive and non-destructive methods for characterising these innovative composite materials.