Abstract: A system for monitoring strain in structural joints has one or more optical ibers embedded in the joint between the structural members. The joint may be fastened using fasteners such as rivets or bonded using an adhesive. Strain on the joined members is transmitted to the fiber, deforming it. An optical reflectometer connected to one end of the fiber injects an optical signal into the fiber and detects the reflection of the signal. The time period between injection of the signal and detection of the reflection is used to localize the area of stress along the fiber.

Abstract: A method and apparatus for detecting changes in the structural strength of bonded joint. Changes in one or more dielectric properties of the bonding adhesive, such as resistance and capacitance, are monitored by a microdielectrometer. A change in a bond dielectric measurement is indicative of a moisture intrusion in the bond and a corresponding weakening of the structural integrity of the bond. A warning or indication of the bond degradation is provided in response to such changes.

Abstract: A corrosion monitoring system having one or more anode elements made of a suitable anodic material that corrodes preferentially with respect to the structure being protected. The resistance of each anode wire is continuously or periodically monitored. The presence of moisture between an anode and the structure being monitored creates a current path and causes galvanic corrosion. The anode wire will begin to corrode, but the structural members will remain uncorroded until the anode has been completely consumed. The monitoring system uses the rate of change in anode resistance to extrapolate a prediction of the time remaining before the structure being protected begins to corrode.