Use of optical fibre sensors to detect and monitor damage in bonded composite repairs of cracked metallic components

摘要

The application of bonded composite patches to repair or reinforce defective metallic structures is becoming recognised as a very effective versatile procedure for many types of problems. Immediate applications of bonded patch applications are inthe fields of repair of cracking, localized reinforcement after removal of corrosion damage and for reduction of fatigue strain. The goal for very demanding repair applications is to incorporate sensors, actuators and electronics in repair systems - smart repair systems - to monitor and report on the health of the repair and the repaired structure, as well as to actuate in order to prevent damage or failure of the repaired structure. The current research is mainly focusing on the assessment of new sensorswhich may be incorporated in bonded repair systems in order to achieve in-situ real-time measurement of patch integrity and effectiveness. This application would allow the operator to move away from current costly time-based maintenance procedures towardreal-time health condition monitoring of the bonded repair and the repaired structure. These systems would allow timely decisions on preventative and schedule maintenance before failure of the repair or repaired structure.A study was conducted in evaluating the use of embedded and surface mounted optical fibre sensors in detecting and monitoring crack growth of cracked metallic structures repaired with bonded patches. Techniques for embedding optical fibres in boronfibre/epoxy resin patches were developed in this work. The experimental work on a crack patched specimen has shown that optical fibre sensors embedded in composite patches have the potential to detect and monitor crack growth in the metallic sub-structure.