Fiber optic sensors system for high-temperature monitoring of aerospace structures

Latini, V.; Striano, V.; Coppola, Giuseppe; Rendina, Ivo

doi:10.1117/12.722269

Cited by 17 publications

(11 citation statements)

References 3 publications

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“…Being small, insensitive to electromagnetic radiation, resistant to corrosive environments, capable of multiplexing and relatively cheap to manufacture, FOSs are, at a first glance, ideally suited to perform sensing in harsh environments as those found in fossil fuel extraction and processing, nuclear power plants, combustion and gas turbine engines. Indeed, there are experiments described in the literature that involve simultaneous measurements by FOSs and thermocouples [ 3 , 4 , 5 ] and show similar temperature measurement results.…”

Section: Introductionmentioning

confidence: 81%

Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing

Grobnic

Hnatovsky

Dedyulin

et al. 2021

Sensors

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High-temperature-resistant fiber Bragg gratings (FBGs) are the main competitors to thermocouples as sensors in applications for high temperature environments defined as being in the 600–1200°C temperature range. Due to their small size, capacity to be multiplexed into high density distributed sensor arrays and survivability in extreme ambient temperatures, they could provide the essential sensing support that is needed in high temperature processes. While capable of providing reliable sensing information in the short term, their long-term functionality is affected by the drift of the characteristic Bragg wavelength or resonance that is used to derive the temperature. A number of physical processes have been proposed as the cause of the high temperature wavelength drift but there is yet no credible description of this process. In this paper we review the literature related to the long-term wavelength drift of FBGs at high temperature and provide our recent results of more than 4000 h of high temperature testing in the 900 –1000°C range. We identify the major components of the high temperature wavelength drift and we propose mechanisms that could be causing them.

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Section: Introductionmentioning

confidence: 81%

Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing

Grobnic

Hnatovsky

Dedyulin

et al. 2021

Sensors

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“…The diameter of the heating spot is 20 mm, and the distance from the heating lens to the specimen is 200 mm. To simulate a realistic heating condition existing of the outer surfaces of airframes or spaceframes, the specimen is heated vertically from the bottom. During the test, the laser heating lens is moved vertically and horizontally by adjusting a screw gear at the bottom of the laser heater.…”

Section: Methodsmentioning

confidence: 99%

Measurement of high‐temperature strains in superalloy and carbon/carbon composites using chemical composition gratings

Xie

Meng

Jin

et al. 2016

Strain

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This paper describes an experimental and signal processing technique to perform high temperature tests on superalloy (INCONEL) and carbon/carbon structures using silica‐based chemical composition gratings (CCGs). The results obtained from applying this technique at 940°C in superalloys and 950°C for carbon/carbon (C/C) composites are benchmarked against data obtained from four different methods. The results show that the wavelength responses of the CCGs bonded on the superalloy and on the C/C plate increase nonlinearly with increasing temperatures. The temperature‐dependent strain transfer coefficients recorded during the superalloy tests show quite stable results below 600 °C and tend to slightly decrease thereafter. The values of the strain transfer coefficients below 1000 °C are significantly affected by the thermal expansion coefficient of the substrate material and the interface. We demonstrate that the strain transfer coefficient calculation method used in this paper is not suitable for low and/or negative expansion material. The results of the relative errors show that the CCGs‐F method based on the quadratic dependence of the wavelength shift versus the temperature appears to be the best to estimate the mechanical strains within the interval of temperatures considered and the measurement accuracy. The relative errors measured between 200 °C and 1000 °C are less than 5%.

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“…The experimental setup used in this work (Figure 1) was designed to simulate a realistic service condition represented by a thermal protection shield (TPS) on a hot external structure, like in hypersonic vehicles [42,43]. The UHTC specimen [40] was heated vertically from the bottom through the hole on the workbench.…”

Section: Experimental Designmentioning

confidence: 99%

Application of CCG Sensors to a High-Temperature Structure Subjected to Thermo-Mechanical Load

Xie

Meng

Jin

et al. 2016

Sensors

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This paper presents a simple methodology to perform a high temperature coupled thermo-mechanical test using ultra-high temperature ceramic material specimens (UHTCs), which are equipped with chemical composition gratings sensors (CCGs). The methodology also considers the presence of coupled loading within the response provided by the CCG sensors. The theoretical strain of the UHTCs specimens calculated with this technique shows a maximum relative error of 2.15% between the analytical and experimental data. To further verify the validity of the results from the tests, a Finite Element (FE) model has been developed to simulate the temperature, stress and strain fields within the UHTC structure equipped with the CCG. The results show that the compressive stress exceeds the material strength at the bonding area, and this originates a failure by fracture of the supporting structure in the hot environment. The results related to the strain fields show that the relative error with the experimental data decrease with an increase of temperature. The relative error is less than 15% when the temperature is higher than 200 °C, and only 6.71% at 695 °C.

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Fiber optic sensors system for high-temperature monitoring of aerospace structures

Cited by 17 publications

References 3 publications

Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing

Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing

Measurement of high‐temperature strains in superalloy and carbon/carbon composites using chemical composition gratings

Application of CCG Sensors to a High-Temperature Structure Subjected to Thermo-Mechanical Load

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