Temperature Dependence of Glue-Induced Birefringence in Surface-Attached FBG Strain Sensors

Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

doi:10.1109/jlt.2015.2507621

Cited by 15 publications

(11 citation statements)

References 25 publications

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“…Based on the research described in the literature, the phenomenon of glue crawling under the influence of temperature can be distinguished [1,2], however, the research in the scope of the presented topic was carried out at a constant laboratory temperature and therefore this phenomenon did not occur.…”

Section: Results Analysismentioning

confidence: 99%

Analisys of the Influence of Glue Joints on the Measurement of Physical Properties of Structural Elements Using Fiber Bragg Grating

Zieliński

Zychowicz

2020

IAPGOS

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The research presents the analysis of the influence of the glue connection on the measurement of elongation of stainless steel and aluminum samples by means of fiber Bragg grating (FBG) with uniform fibers used as a measuring transducer. Research indicates two possible factors affecting the deformation of the transmission spectrum obtained during elongation measurement. One of them is the type of adhesive that is used to make the connection between the fiber Bragg grating and the tested sample. The second possible factor is method of connection's execution. The need for research on glue connection resulted from the formation of defects mainly in the form of numerous side bands visible in the transmission spectrum during the measurement of elongations. The test results were presented in the form of graphs obtained on the basis of transmission characteristic.

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Section: Results Analysismentioning

confidence: 99%

Analisys of the Influence of Glue Joints on the Measurement of Physical Properties of Structural Elements Using Fiber Bragg Grating

Zieliński

Zychowicz

2020

IAPGOS

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“…Additionally, it was assumed that significant glue-induced forces occur only below 110 °C, which is the beginning of the glue’s glass transition range [13,28]. Therefore, all Bragg wavelength changes were calculated with respect to the reference temperature of 110 °C, at which the model was considered to be stress-free.…”

Section: Simulation: Determination Of Glue-independent Fbg Signalsmentioning

confidence: 99%

“…Gluing the FBG over its entire sensor length adds several challenges to the task, as the glue induces significant temperature-dependent transversal forces to the fiber, mostly because of a mismatch in the coefficients of thermal expansions (CTE) of the fiber, glue, and specimen [12,13]. These glue-induced forces alter the FBG’s sensor response, especially during temperature changes, and have to be considered in temperature measurements with surface-attached FBG elements [13,14]. This is aggravated by the fact that the used glue has to assure full strain transfer in a wide thermal range, e.g., between −40 °C and 150 °C, which requires the use of a glue with a high glass transition temperature.…”

Section: Introductionmentioning

confidence: 99%

“…This is aggravated by the fact that the used glue has to assure full strain transfer in a wide thermal range, e.g., between −40 °C and 150 °C, which requires the use of a glue with a high glass transition temperature. Thermally cured epoxy resins have been shown to fulfill this requirement, but tend to induce high values of glue-induced birefringence, especially at low temperatures [13]. Additionally, temperature-dependent creeping behavior and stress-relaxation have been observed in thermally cured epoxy resin [15,16].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, temperature-dependent creeping behavior and stress-relaxation have been observed in thermally cured epoxy resin [15,16]. Due to the relaxation characteristics of the adhesive, the amount of glue-induced stress and its influence on the FBG sensor signal varies not only with temperature but also with time, leading to a hysteresis behavior of surface-glued FBGs during temperature cycles [13]. Moreover, epoxy resins are prone to absorb humidity up to 6% of their mass, causing a swelling of the glue depending on their chemical composition, the exposure time, and the concentration [17,18].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Strain-Independent Temperature Measurements with Surface-Glued Polarization-Maintaining Fiber Bragg Grating Sensor Elements

Hopf

Fischer

Bosselmann

et al. 2019

Sensors

Self Cite

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A novel technique for strain and temperature decoupling with surface-glued fiber Bragg gratings (FBGs) is presented and applied for strain-independent temperature measurements in a temperature range between −30 °C and 110 °C with uncertainties below 4 °C over the entire measurement range. The influence of temperature-dependent glue-induced transversal forces on the fiber sensor could be eliminated with a sensor element consisting of two FBGs in identical polarization-maintaining fibers that were spliced perpendicular to each other. After aligning and gluing the sensor element with its optical axes parallel and perpendicular to the specimen, the averaged Bragg wavelength shifts of both FBGs were proven to be independent of the glue’s influence and therefore independent of any change in the material characteristics of the glue, such as aging or creeping behavior. For the first time, this methodology enables temperature measurements with surface-attached bare FBGs independently of arbitrary longitudinal and glue-induced strains. This is of great value for all applications that rely on a fully glued sensor design, e.g., in applications with high electromagnetic fields, on rotating parts, or in vacuum for space applications.

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Simultaneous strain and temperature measurement using a single fiber Bragg grating embedded in a composite laminate

Singh

Berggren

Zhu

et al. 2017

Smart Mater. Struct.

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This paper presents a fiber Bragg gating (FBG) sensor that can be surface mounted for simultaneous strain and temperature measurements. By embedding a conventional FBG sensor in a composite laminate, local birefringence is introduced, which causes the bandwidth of the FBG spectrum to vary with strain as well as temperature. As such, temperature and strain can be simultaneously determined from two FBG spectral parameters, i.e. the spectral bandwidth and the Bragg wavelength. Techniques for improving the spectrum of the FBG-composite sensor and for inversely determining the strain and temperature from the measured FBG spectral parameters are discussed. Thermal–mechanical testing of the FBG-composite sensor was carried out to validate the sensor performance. The measurement errors, within one standard deviation, for the strain and temperature measurements were found to be ±62 με and ±1.94 °C, respectively.

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Temperature Dependence of Glue-Induced Birefringence in Surface-Attached FBG Strain Sensors

Cited by 15 publications

References 25 publications

Analisys of the Influence of Glue Joints on the Measurement of Physical Properties of Structural Elements Using Fiber Bragg Grating

Analisys of the Influence of Glue Joints on the Measurement of Physical Properties of Structural Elements Using Fiber Bragg Grating

Strain-Independent Temperature Measurements with Surface-Glued Polarization-Maintaining Fiber Bragg Grating Sensor Elements

Simultaneous strain and temperature measurement using a single fiber Bragg grating embedded in a composite laminate

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