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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

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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.

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Three-dimensional (3-D) finite element (FE) model: (a) one half of a meshed model of a metal-packaged RFBG strain sensor, and (b) boundary conditions and applied load.
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sensors-17-00431-f003: Three-dimensional (3-D) finite element (FE) model: (a) one half of a meshed model of a metal-packaged RFBG strain sensor, and (b) boundary conditions and applied load.

Mentions: The 3-D FE modeling approach, which has been proposed and detailed in our previous work [17], was applied to modeling of the metal-package RFBG strain sensor prototype in the present work in order to find the state of stress and strain in the embedded optical fiber. The mechanical properties of the materials used in the 3-D FE analysis are listed in Table 1. One half of the structural model of a specimen with a metal-packaged RFBG strain sensor attached was discretized with 134,952 hexahedral elements (SOLID185) due to the symmetry of both the geometry and loading. One half of the metal-packaged RFBG sensor was selected for mesh refinement and discretized with 125,952 hexahedral mesh elements, as shown in Figure 3a. As seen, finer mesh sizes were chosen at the location of the optical fiber and the sputtered and electroplated metallic layers. The surface to be connected on the specimen was defined as the target element (TARGE170), whilst the surface to be connected on the substrate was defined as the contact element (CONTA173). Structural loads are transferred from the surface of the specimen to the surface of the substrate via the spot-weld connection points. The boundary conditions and the load were applied to the one half of the structural model, as shown in Figure 3b.


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
Three-dimensional (3-D) finite element (FE) model: (a) one half of a meshed model of a metal-packaged RFBG strain sensor, and (b) boundary conditions and applied load.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

sensors-17-00431-f003: Three-dimensional (3-D) finite element (FE) model: (a) one half of a meshed model of a metal-packaged RFBG strain sensor, and (b) boundary conditions and applied load.
Mentions: The 3-D FE modeling approach, which has been proposed and detailed in our previous work [17], was applied to modeling of the metal-package RFBG strain sensor prototype in the present work in order to find the state of stress and strain in the embedded optical fiber. The mechanical properties of the materials used in the 3-D FE analysis are listed in Table 1. One half of the structural model of a specimen with a metal-packaged RFBG strain sensor attached was discretized with 134,952 hexahedral elements (SOLID185) due to the symmetry of both the geometry and loading. One half of the metal-packaged RFBG sensor was selected for mesh refinement and discretized with 125,952 hexahedral mesh elements, as shown in Figure 3a. As seen, finer mesh sizes were chosen at the location of the optical fiber and the sputtered and electroplated metallic layers. The surface to be connected on the specimen was defined as the target element (TARGE170), whilst the surface to be connected on the substrate was defined as the contact element (CONTA173). Structural loads are transferred from the surface of the specimen to the surface of the substrate via the spot-weld connection points. The boundary conditions and the load were applied to the one half of the structural model, as shown in Figure 3b.

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