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An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron – Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications

View Article: PubMed Central - PubMed

ABSTRACT

Local strain measurements are considered as an effective method for structural health monitoring of high-temperature components, which require accurate, reliable and durable sensors. To develop strain sensors that can be used in higher temperature environments, an improved metal-packaged strain sensor based on a regenerated fiber Bragg grating (RFBG) fabricated in hydrogen (H2)-loaded boron–germanium (B–Ge) co-doped photosensitive fiber is developed using the process of combining magnetron sputtering and electroplating, addressing the limitation of mechanical strength degradation of silica optical fibers after annealing at a high temperature for regeneration. The regeneration characteristics of the RFBGs and the strain characteristics of the sensor are evaluated. Numerical simulation of the sensor is conducted using a three-dimensional finite element model. Anomalous decay behavior of two regeneration regimes is observed for the FBGs written in H2-loaded B–Ge co-doped fiber. The strain sensor exhibits good linearity, stability and repeatability when exposed to constant high temperatures of up to 540 °C. A satisfactory agreement is obtained between the experimental and numerical results in strain sensitivity. The results demonstrate that the improved metal-packaged strain sensors based on RFBGs in H2-loaded B–Ge co-doped fiber provide great potential for high-temperature applications by addressing the issues of mechanical integrity and packaging.

No MeSH data available.


Related in: MedlinePlus

Von Mises stress distribution in the metal-packaged RFBG strain sensor at a strain of 0.26% applied to the test specimen at room temperature.
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sensors-17-00431-f012: Von Mises stress distribution in the metal-packaged RFBG strain sensor at a strain of 0.26% applied to the test specimen at room temperature.

Mentions: To avoid undesirable plastic deformation of the P91 steel specimen, the specimen was only tested up to ~0.08% strain, corresponding to ~0.12% strain in the RFBG obtained from the FE simulation. For further loading, the verified linear trend may be maintained up to the strain limit of the bare RFBG (i.e., ~0.4% at 4 N as discussed in previous sections, corresponding to ~0.26% strain in the specimen) which restricts the strain measurement range of the sensor. However, this is also largely dependent on the behavior of the substrate. At a strain of 0.26%, the von Mises stresses occurring in the substrate are determined from the FE modeling at the room temperature, as shown in Figure 12. Assuming the spot welds with sufficient strength to transfer the structural loads from the specimen to the sensor, the maximum von Mises stress occurring in the nickel layer far exceeds the yield strength of 59.0 MPa [32] in addition to yielding occurring in the region of the spot welds, which confirms that the strain measurement range of the sensor is limited not only by the strain range of the RFBG, but also by the strength of the metallic packaging materials and the spot welds.


An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron – Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications
Von Mises stress distribution in the metal-packaged RFBG strain sensor at a strain of 0.26% applied to the test specimen at room temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5375717&req=5

sensors-17-00431-f012: Von Mises stress distribution in the metal-packaged RFBG strain sensor at a strain of 0.26% applied to the test specimen at room temperature.
Mentions: To avoid undesirable plastic deformation of the P91 steel specimen, the specimen was only tested up to ~0.08% strain, corresponding to ~0.12% strain in the RFBG obtained from the FE simulation. For further loading, the verified linear trend may be maintained up to the strain limit of the bare RFBG (i.e., ~0.4% at 4 N as discussed in previous sections, corresponding to ~0.26% strain in the specimen) which restricts the strain measurement range of the sensor. However, this is also largely dependent on the behavior of the substrate. At a strain of 0.26%, the von Mises stresses occurring in the substrate are determined from the FE modeling at the room temperature, as shown in Figure 12. Assuming the spot welds with sufficient strength to transfer the structural loads from the specimen to the sensor, the maximum von Mises stress occurring in the nickel layer far exceeds the yield strength of 59.0 MPa [32] in addition to yielding occurring in the region of the spot welds, which confirms that the strain measurement range of the sensor is limited not only by the strain range of the RFBG, but also by the strength of the metallic packaging materials and the spot welds.

View Article: PubMed Central - PubMed

ABSTRACT

Local strain measurements are considered as an effective method for structural health monitoring of high-temperature components, which require accurate, reliable and durable sensors. To develop strain sensors that can be used in higher temperature environments, an improved metal-packaged strain sensor based on a regenerated fiber Bragg grating (RFBG) fabricated in hydrogen (H2)-loaded boron–germanium (B–Ge) co-doped photosensitive fiber is developed using the process of combining magnetron sputtering and electroplating, addressing the limitation of mechanical strength degradation of silica optical fibers after annealing at a high temperature for regeneration. The regeneration characteristics of the RFBGs and the strain characteristics of the sensor are evaluated. Numerical simulation of the sensor is conducted using a three-dimensional finite element model. Anomalous decay behavior of two regeneration regimes is observed for the FBGs written in H2-loaded B–Ge co-doped fiber. The strain sensor exhibits good linearity, stability and repeatability when exposed to constant high temperatures of up to 540 °C. A satisfactory agreement is obtained between the experimental and numerical results in strain sensitivity. The results demonstrate that the improved metal-packaged strain sensors based on RFBGs in H2-loaded B–Ge co-doped fiber provide great potential for high-temperature applications by addressing the issues of mechanical integrity and packaging.

No MeSH data available.


Related in: MedlinePlus