Structural Health Monitoring Using Fiber Optic Sensing

Systems Planning and Analysis, Inc. (SPA) proposes to develop an open architecture structural health monitoring system for naval ships based on fiber optic Bragg grating and digital telecommunications technologies. This dual-purpose system will allow for simultaneous sensing and transmission of existing analog data streams afloat (i.e., communications, fire control, resistance strain data, etc.) and digital strain data from fiber strain sensors distributed along multiple sensing fibers. Using wavelength division multiplexed sensors along each fiber path, structural strains of the primary hull and other substructures will be measured to provide real-time, on-line health monitoring of the vessel during operations. During the proposed effort, a prototype system will be built with a 2-sensor array of 4 sensors each, 2 transmission nodes, and a 100m data bus consisting of Mil-Spec 85049 digital cable. SPA will test this system on a dynamically-scaled ship hull structure at a bandwidth of 20 Hz, while simultaneously transmitting an analog single frequency TTL current modulation function (to simulate analog data transmission). SPA will develop a software package to record and process the sensor data for real-time assessment of the hull to provide predictions of the remaining life. SPA will interface the prototype system with the naval structural assessment code, ULTSTR, in the Phase I option, to facilitate acceptance of the system in the fleet.