SBIR-STTR Award

Stress monitoring in composite materials is difficult but useful for testing to compare measurements with modeling and to monitor flexing and vibration under load. There are only a limited number of methods to measure strain that are suitable to be embedded in a composite material and all either expensive or complex. This proposal is for a new and novel strain sensor. It uses a small diameter wire coated with a magnetic film. The magnetic film dominates the impedance of the wire and is strain sensitive. The wire is very cheap to manufacture and the readout electronics simple so that overall system cost is low with a potential cost advantage over fiber optic sensors of a factor of 100. This proposal introduces a new technology with potentially wide applications. The ability to plate controlled magnetic films on small diameter wires opens multiple applications. The wire can be used to obtain curing information of a composite in addition to information on external strain. Since the system can be used in a modified array structure, the strain at different points can be measured versus time, giving information on the vibration of the structure, including modal analysis.Anticipated Benefits/Commercial Applications: This proposal addresses one specific application of a new technology, a wire sensor for embedding in composites to monitor internal strain, both initially and as the composite ages. 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. Additional applications, including shielding and power filtering, are possible with a slightly different configuration of the wire.

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 limited number 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 wire coated 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 curing information 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 and throughout 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.

Keywords:
sensors, magnetic, strain, magnetostrictive