Fiber-optic sensors embedded within advanced composite materials represent a new branch of engineering with the potential to greatly enhance the confidence and use of these materials. An overview of our developments toward fiber-optic-based Smart Composite Structures is presented. This includes a review of our development of a full-scale fiber-optic damage assessment system for an aircraft composite leading edge and the confirmation of the feasibility of such a resident fiber-optic structural integrity monitoring system. We report on the development and characterization of fiber-optic strain gauges that have been embedded within composite materials and used to measure the internal strain field or detect load-induced acoustic emission from within composite specimens, and explore the feasibility of undertaking optoacoustic cure monitoring. A discussion is also provided of two issues: fiber-optic strain sensitivity in light of the recent theoretical work of Sirkis and Haslach and thermally induced apparent strain. Lastly, mention is made of our passive, fast response, wavelength demodulation system for the Bragg grating sensor as this holds promise for the eventual development of a multiplexed, multisensing optoelectronic chip that could overcome the interconnect barrier to the practical implementation of Smart Structure technology.
