Comparison between different fiber coatings and adhesives on steel surfaces for distributed optical strain measurements based on Rayleigh backscattering

Weisbrich, Martin; Holschemacher, Klaus

doi:10.5194/jsss-7-601-2018

Cited by 34 publications

(49 citation statements)

References 16 publications

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“…The FBGs are femtosecond-written in a bend insensitive optical fibre with polyimide coating (SM1250BI, Fibercore, Southampton, UK). Polyimide coating was chosen as such coating will not exhibit any strain loss due to slippage between the coating and cladding [ 28 ]. All the FBGs have a length of 3 mm and the reflectivity above 40%.…”

Section: Methodsmentioning

confidence: 99%

Fetal Movement Counting Using Optical Fibre Sensors

Abeywardena

Vanheusden

Walker

et al. 2020

Sensors

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Daily fetal movement counting based on maternal perception is widely deployed to monitor fetal wellbeing. However, the counting performed by the mother is prone to errors for various reasons. There are limited devices on the market that can provide reliable and automatic counting. This paper presents a prototype of a novel fetal movement monitoring device based on fibre Bragg grating sensors. Deformation of the skin caused by a fetal movement can lead to a change of the strain and stress on the optical fibre sensors, therefore can induce distortions to the breathing pattern of the mother. In the study data was gathered by the sensors through strain measurement and was post-processed using independent component analysis (ICA) and high-pass filtering to show the instances of the fetal movements. Information gathered during user trials with the prototype suggests that the system detects significantly higher numbers of fetus movements than that observed based on the mother’s perception. Among the various techniques available for fetal movement monitoring, fibre optic sensing provides many advantages including multiplex capability, flexibility and minimal size, making the concept an attractive solution for reliable monitoring of antenatal fetal movements.

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Section: Methodsmentioning

confidence: 99%

Fetal Movement Counting Using Optical Fibre Sensors

Abeywardena

Vanheusden

Walker

et al. 2020

Sensors

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“…With two conventional coatings acrylate and polyimide, the results from the literature should be verified and form a baseline for comparison [10,16,22,27]. The third coating material Ormocer R was developed especially for FBG sensors and showed good strain transfer properties in previous investigations with bonded sensors [9,31]. Table 1 summarizes the fiber types and their most important characteristics.…”

Section: Experimental Program 21 Coating Materials and Concrete Mixturementioning

confidence: 99%

“…The fiber optic measurement method with its distributed measurement generates a considerable amount of data [31]: The method records a strain value for every 2.56 mm of the measuring fiber. To minimize the effect of the measurement noise, the strain values were recorded at a measuring rate of 1 Hz for 30 s at each measurement time t i (Tab.…”

Section: Evaluation Processmentioning

confidence: 99%

“…The bond between coating material and concrete is critical for the strain transfer. For the slip between the fiber coating and the fiber cladding, the stiffness of the coating material is decisive for adequate transfer [3,30,31]. Various research groups have analyzed the effect of the fiber coating on the strain transfer during measurements in the matrix.…”

Section: Introductionmentioning

confidence: 99%

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Comparison among Different Fiber Coatings on the Concrete Shrinkage Test for Distributed Optical Strain Measurements based on Rayleigh Backscattering

Weisbrich¹,

Holschemacher²,

Bier³

2019

Preprint

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The fiber optic strain measurement based on Rayleigh scattering has recently become increasingly popular in automotive or mechanical engineering for strain monitoring and in the construction industry in general, especially structural health monitoring. This technology enables the monitoring of strain along the entire fiber length. Several publications have been published, particularly on the applications to the structural component. This article addresses integrating optical fibers of different coatings into the concrete matrix to measure the shrinkage deformations. In this context, three different coating types were investigated regarding their strain transfer. The fibers were integrated into fine-grained concrete prisms, and the shrinkage strain was compared with a precise dial gauge. The analysis shows a high correlation between the reference method and the fiber measurement, especially with the Ormocer coating. The used acrylate coating is also consistent in the middle area of the specimen but requires a certain strain introduction length to indicate the actual strain. The main result of this study is a recommendation for fiber coatings for shrinkage measurement in fine grain concretes using the distributed fiber optic strain measurement. In addition, the advantages and disadvantages of the measurement method are presented.

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“…This requirement applies both to the protective coating material of the fiber, as well as to the modified part of the MCF, in which the FBG array is inscribed. In particular, when the MCF is embedded in a composite material, a high degree of adhesion of the protective coating with the glass cladding of the optical fiber and with the external material is required [7,8]. During the curing of composite materials, such as carbon fiber prepregs, the temperature can reach 180°C for epoxy/carbon fiber composites [9], and 350°C…”

Section: Introductionmentioning

confidence: 99%

Durable shape sensor based on FBG array inscribed in polyimide-coated multicore optical fiber

et al. 2019

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The paper presents a novel three-dimensional quasi-continuous shape sensor based on an FBG array inscribed by femtosecond laser pulses into a 7-core optical fiber with a polyimide protective coating. The measured bending sensitivity of individual FBGs ranges from 0.046 nm/m −1 to 0.049 nm/m −1. It is shown that the sensor allows for reconstructing 2and 3-dimensional shapes with high accuracy. Due to the high value of the core aperture and individual calibration of each FBG we were able to measure the smallest reported bending radii down to 2.6 mm with a record accuracy of ∼1%. Moreover, we investigate the magnitude of the errors of curves reconstruction and errors associated with measurement of curvature radii in the range from 2.6 to 500 mm. The main factors affecting the accuracy of measurements are also discussed. The temperature resistance of both the inscribed FBG structures and of the protective coating, along with the high mechanical strength of the polyimide, makes it possible to use the sensor in harsh environments or in medical and composite material applications.

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Comparison between different fiber coatings and adhesives on steel surfaces for distributed optical strain measurements based on Rayleigh backscattering

Cited by 34 publications

References 16 publications

Fetal Movement Counting Using Optical Fibre Sensors

Fetal Movement Counting Using Optical Fibre Sensors

Comparison among Different Fiber Coatings on the Concrete Shrinkage Test for Distributed Optical Strain Measurements based on Rayleigh Backscattering

Durable shape sensor based on FBG array inscribed in polyimide-coated multicore optical fiber

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