Use of an In-Situ Electrochemical Sensor for Predictive Assessment of Bonded Repairs

DACCO SCI, INC., (DSI), together with DynCorp, proposes a Phase I SBIR program to use an electrochemical impedance spectroscopy (EIS)-based corrosion sensor to monitor the integrity of an adhesive bondline between a repair patch and the damaged structureof an aircraft. Using this sensor approach to detect moisture intrusion into a repair bondline will give advance warning of potential environmentally induced bondline deterioration and enable predictive assessment. Corrective action can then be takenprior to permanent disruption of the bondline. This monitoring technology could eventually be used as a standard tool in the suite of nondestructive evaluation (NDE) methods for evaluating the integrity of bonded repairs. Increased confidence andreliability of repair patches will facilitate repair of aircraft, rotorcraft, and other systems. The sensored patch will allow larger cracks (closer to the critical crack length) to be repaired with reasonable inspection intervals. The cost avoidanceachieved by both reactive and proactive patching and the resulting extension of service lifetimes will make system life-cycle costs more affordable.Reliability of bonded repairs will increase as a result of this health monitoring. Military and commercialair fleet readiness and safety will correspondingly increase with a potential decrease in costs as service lifetimes are extended. Other applications would include storage tanks, pipelines, weapon systems and components, and vehicles.