137. EVALUATION OF FIBER OPTIC STRAIN SENSORS FOR APPLICATIONS IN STRUCTURAL HEALTH MONITORING

Department: Mechanical & Aerospace Engineering
Faculty Advisor(s): John B. Kosmatka

Primary Student
Name: Benjamin Levi Martins
Email: blmartin@ucsd.edu
Phone: 858-901-4050
Grad Year: 2017

Abstract
In-situ structural health monitoring has gained increased research attention in recent years as a way to increase the utility of aging metallic and unproven composites as primary structural components in aerospace structures. Successful implementation of a structural health monitoring system would usher in the transition from time-based to condition-based maintenance in aircraft structures, with associated advantages, like advanced certification methods, improved operational efficiency and increased safety. The current study focuses on utilizing a network of strain based fiber optic sensors which can provide both global behavior as well as localized impending damage of metallic and composite structures. The lightweight, easily multiplexed fiber-optic strain sensors make it possible to establish an in-situ, large scale, distributed network of thousands of sensors with negligible weight penalty. In the current study the noise levels present on the time history measurements for two types of fiber optic strain sensing systems were compared to that of conventional accelerometers and laser vibrometer. Experimental studies were conducted in which the modal models developed by the optical fiber and conventional sensor types were compared. It was found that the wavelength division multiplexed optical fibers performed as well or better than the accelerometer and laser vibrometer in measuring the plate?s dynamic response. As a result, the wavelength division multiplexed fiber was used to develop modal models of the baseline plate, in addition to the plate with added localized mass (simulated damage condition). Previously developed damage indicator functions were employed to show the ability of the fiber optic sensors to detect and locate damage on the plate. These damage indicator functions were shown to yield more definitive evidence of damage than looking at frequency shifts or mode shapes alone.

Industry Application Area(s)
Aerospace, Defense, Security | Civil/Structural Engineering | Energy/Clean technology

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