Strength degradation of lightguide fibres in roomtemperature water

Kurkjian, Charles R.; Matthewson, M. John

doi:10.1049/el:19960492

Cited by 14 publications

(6 citation statements)

References 9 publications

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“…Evaporation deposition cannot be used for metals with a high melting point, such as nickel and titanium. The electroless plating method exposes fibers to corrosives such as water and hydrochloric acid, that can cause substantial degradation of strength [25].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of a metal-packaged regenerated fiber Bragg grating strain sensor for structural integrity monitoring of high-temperature components

Tu¹,

Tu²

2014

Smart Mater. Struct.

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Assessment of the structural integrity of components operating at high temperatures requires the development of novel sensors to measure strain. A metal-packaged regenerated fiber Bragg grating (RFBG) sensor is developed for measurement of strain using titanium–silver magnetron sputtering and nickel electroplating. The strain response of the sensor mounted onto a flat tensile specimen by spot welding is evaluated by uniaxial tensile tests at constant temperatures ranging from room temperature to 400 °C. Similar tests are performed on a bare RFBG sensor for comparison. The metal-packaged RFBG strain sensor exhibits higher strain sensitivity than that of the bare RFBG sensor, as well as good linearity, stability and repeatability of strain measurements. A three-dimensional finite element model of the sensor is established to predict the strain sensitivity based on the sensing principle of the fiber Bragg grating. Comparisons of the experimental results with the numerical predictions for the strain sensitivity show a satisfactory agreement. These results demonstrate that the metal-packaged RFBG strain sensors can be successfully fabricated by combining magnetron sputtering with electroplating, and provide great promise for structural integrity monitoring of high-temperature components.

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Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of a metal-packaged regenerated fiber Bragg grating strain sensor for structural integrity monitoring of high-temperature components

Tu¹,

Tu²

2014

Smart Mater. Struct.

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“…However, the presence of a knee in the graph marking a sudden decrease in time to failure has been reported [3][4][5]. The intrinsic strength of optical fibre is the strength measured in the absence of the corrosion.…”

Section: Static Fatigue Of Optical Fibrementioning

confidence: 98%

Mechanical reliability of optical fibre for strain sensors

Shazly

Kukureka

2005

SPIE Proceedings

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The reliability of optical fibre for sensor applications is an important issue since they are embedded in structures. The production of these sensors sometimes requires that the coating is stripped from the optical fibres with hot sulphuric acid. Tests conducted on the static fatigue of optical fibres under water, where the time to failure is measured at different stresses showed a deviation from the power-law equation. This indicates an increase in the stress corrosion parameter, n, at lower stress. Tests done using a two-point bend machine to measure the fracture strength of fibre at different time intervals after previous loading to a fixed stress showed a slight increase with time before the strength starts decreasing. This can be explained by the suggestion that the silica bonds deform by twisting to decrease the stretch in the bonds themselves before cracking. However, this might be a problem for optical fibres strain sensors used at high stress.

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“…Unfortunately, the provision of suitable packaging and attachment methods to ensure long-term sensor reliability remains a challenge [5]. Designing sensors for the surfaces of wind turbine foundations is particularly challenging as the structure is buried and exposed to the damaging effects of soil shear and water [6]. Furthermore, strong adhesion and good strain transfer are difficult to achieve with conventional sensor-bonding methods such as epoxy, as excavated concrete surfaces may be wet, uneven from cracking and highly unstable due to spalling [7].…”

Section: Introductionmentioning

confidence: 99%

Metal-packaged fibre Bragg grating strain sensors for surface-mounting onto spalled concrete wind turbine foundations

et al. 2015

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In this work, we demonstrate preliminary results for a hermetically sealed, metal-packaged fibre Bragg grating strain sensor for monitoring existing concrete wind turbine foundations. As the sensor is bolted to the sub-surface of the concrete, it is suitable for mounting onto uneven, wet and degraded surfaces, which may be found in buried foundations. The sensor was able to provide reliable measurements of concrete beam strain during cyclic three-and four-point bend tests. The strain sensitivity of the prototype sensor is currently 10 % of that of commercial, epoxied fibre strain sensors.

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Strength degradation of lightguide fibres in roomtemperature water

Cited by 14 publications

References 9 publications

Fabrication and characterization of a metal-packaged regenerated fiber Bragg grating strain sensor for structural integrity monitoring of high-temperature components

Fabrication and characterization of a metal-packaged regenerated fiber Bragg grating strain sensor for structural integrity monitoring of high-temperature components

Mechanical reliability of optical fibre for strain sensors

Metal-packaged fibre Bragg grating strain sensors for surface-mounting onto spalled concrete wind turbine foundations

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