Structural Monitoring Via Embedded Magnetic Wires

Stress monitoring in composite materials is a difficult but necessary endeavor. It is required for testing to compare measurements with modeling predictions as well as to monitor flexing and vibration under load. Presently, there are only a limitednumber f methods to measure strains that are suitable for embedding in a composite material and all are either expensive or complex. This proposal is for development and application of a new and novel strain sensor consisting of a small diameter wirecoated with a magnetic film. The magnetic film dominated the impedance of the overall system cost is low with a potential cost advantage over fiber optic sensors or a factor of 100. The technology of the magnetic sensor make it suitable to obtain curinginformation of a composite. Additionally, it can be used to obtain information on external strain throughout the life of the material. Since the system can be used in a modified array structure, the stain at different points can be measured versus time,giving information on the vibration of the structure, including modal analysis. This proposal addresses one specific application of a new technology, a magnetic sensor for embedding in composites to monitor internal strain, booth during manufacture andthroughout the composite life cycle. Such sensors can be used to monitor the health of advanced composites used for airframes and space applications, as well as more conventional structures such as buildings, bridges, etc.