In situ cure monitoring and In-service impact localization of FRPs using Pre-implanted nanocomposite sensors

Abstract

From manufacturing onset through service, cure progress and structural integrity of fibre-reinforced polymer (FRP) composites are monitored continuously using a single type of pre-implanted nanocomposite sensors. The sensors precisely respond to broadband dynamic strains up to half a megahertz, yet without imposing intrusion to host composites and downgrading the original structural integrity. In conjunction with differential scanning calorimetry and a Sesták–Berggren autocatalytic kinetic model, cure behaviors of FRPs during fabrication are evaluated accurately, in terms of the matrix polymerization degree that is correlated with subtle changes in propagation characteristics of guided ultrasonic waves captured by the pre-implanted sensors. Use of the sensors is subsequently extended to structural integrity monitoring of FRPs that are in service. Experimental validation demonstrates that a transient impact to composites can be localized and imaged with the pre-implanted sensors. This study illustrates an in situ life cycle monitoring approach for FRPs using a single type of permanently implanted sensors with neglectable intrusion to composites.