Discerning Localized Thermal Heating from Mechanical Strain Using an Embedded Distributed Optical Fiber Sensor Network

Abstract

Prior research has demonstrated that distributed optical fiber sensors (DOFS) based on Rayleigh scattering can be embedded in carbon fiber/epoxy composite structures to rapidly detect temperature changes approaching 1000 °C, such as would be experienced during a high energy laser strike. However, composite structures often experience mechanical strains that are also detected during DOFS interrogation. Hence, the combined temperature and strain response in the composite can interfere with rapid detection and measurement of a localized thermal impulse. In this research, initial testing has demonstrated the simultaneous response of the DOFS to both temperature and strain. An embedded DOFS network was designed and used to isolate and measure a localized thermal response of a carbon fiber/epoxy composite to a low energy laser strike under cyclic bending strain. The sensor interrogation scheme uses a simple signal processing technique to enhance the thermal response, while mitigating the strain response due to bending. While our ultimate goal is rapid detection of directed energy on the surface of the composite, the technique could be generalized to structural health monitoring of temperature sensitive components or smart structures.

Multiparameter measurement depending on the cavity-length differentiation characteristics of a microfiber Fabry–Perot interferometer

“…Usually, FBG sensors use only wavelength as the means of detection for a measured parameter, which limits their ability to directly distinguish between different parameters and can easily lead to cross-interference [21,22]. To overcome this problem, researchers have been exploring new approaches and structures, such as the use of multi-grating structures [23][24][25], special fiber structures [26][27][28][29] fiber Fabry-Perot interference [30][31][32][33] structures, polymer coatings [34][35][36][37], and multi-sensor networks [38][39][40] to improve the multiparameter measurement capability and cross-interference resistance of FBG sensors. For example, Fu et al [25] proposed a fiber sensor based on a cascaded long-period fiber grating with a double-clad fiber composite tapered structure.…”

The Characterization Pattern of Overburden Deformation with Distributed Optical Fiber Sensing: An Analogue Model Test and Extensional Analysis

“…Since the widespread application of distributed optical fiber sensing (DOFS) technology into geotechnical and geology engineering [ 12 , 13 ], its abilities for distribution, high accuracy and anti-interference measurement have widely and deeply improved the engineering monitoring efficiency [ 14 , 15 , 16 ]. By virtue of these unique advantages of realizing real-time online monitoring and intelligent remote control [ 17 , 18 ], it becomes an optional solution to the intelligent mining construction and has tremendous potential for application in mining engineering [ 19 , 20 ].…”

High-energy laser detection through thermoelectric generators

“…[5][6][7] Fiber optic sensors are limited by brittleness if manufactured using glass 8 or material degradation at temperatures exceeding 70°C if manufactured using polymethyl methacrylate (PMMA), 9 which would not survive a high laser intensity environment. Additionally, distributed fiber optic sensors require active interrogation and are sensitive to strain in addition to temperature, 10 requiring significant processing effort to isolate the two effects.…”