212. COMPOSITE STRUCTURES WITH EMBEDDED FIBER OPTIC SENSORS
Name: Anthony Joseph Whitaker
Grad Year: 2016
Structural health monitoring is the process of detecting damage to a structure, where damage can be characterized as changes to material/mechanical properties of the structure including plastically deforming the material or loosening bolted connections. Fiber optic cables with fiber Bragg gratings have emerged as a reliable method of locally measuring strain within structures. During the manufacturing of composite structures, the fiber optic cables can be embedded between lamina plies, allowing the ability to measure the strain at any point in the structure. In addition, to the fiber optic sensors being used to see if the local strain at the sensor location is beyond desired limits, an array of sensors can be embedded and used within a structure to determine information about the loading applied to the structure. The work presented in this thesis is to present novel and potential applications of FBG sensors being used to assess the health of the structure. The first application is the dual application of the FBG sensor as a method to determine the strain around a bolt connection as well as the preload of the fastener using a single fiber optic sensor. The composite material around the bolted connections experience stress concentrations and are often the location of damage to the structure, and further damage can be formed if the bolt is loose over the structure's lifetime. The second application is the ability to locate an impact location of a single projectile and to quantify the energy of the projectile. By locating and quantifying the damage, the structural health monitoring system would have the potential to determine if the damage is extensive enough to replace, or if the part can be salvaged and retrofitted, with the system being able to locate the impact in order to replace.