scholarly journals Strain Measurement on Cracks Using Fiber Bragg Gratings for Use in Aircraft Composite Skin Repairs

Aerospace ◽  
2020 ◽  
Vol 7 (9) ◽  
pp. 138
Author(s):  
Aris A. Ikiades
Keyword(s):  
Spectral Characteristics ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Stress Fields ◽  
Composite Repair ◽  
Local Stresses ◽  
Fbg Sensors ◽  
Critical Components ◽  
Co Doped

Fiber Bragg grating (FBG) sensors have been widely used for measurements of strain and temperature in a host of different applications, including aerospace in composite wings, fuselage structures, and other critical components. Here, we report on a method to measure highly localized intense stress fields, generated at the initialization point of a crack, or crack-tip, using Fiber Bragg Gratings (FBG) inscribed in highly photosensitive hydrogenated germanium and boron co-doped fiber. From the spectral characteristics of short and long FBGs, bonded on a test aluminum coupon with a crack, which simulated damaged skins of an aircraft, the local stresses near the cracks were measured and assessed. As a case study, bespoke composite repair patches were designed and bonded on a coupon, incorporating a number of gratings to monitor the stress distribution with applied force in the composite patch, near the crack.

Micro-structured fiber Bragg gratings. Part I: Spectral characteristics

2007 ◽  
Vol 13 (4) ◽  
pp. 281-290 ◽  
Author(s):  
A. Cusano ◽  
A. Iadicicco ◽  
D. Paladino ◽  
S. Campopiano ◽  
A. Cutolo ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings

scholarly journals Sapphire-Derived Fiber Bragg Gratings for High Temperature Sensing

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 946
Author(s):  
Qi Guo ◽  
Zhixu Jia ◽  
Xuepeng Pan ◽  
Shanren Liu ◽  
Zhennan Tian ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Temperature ◽  
Spectral Characteristics ◽  
Fiber Bragg Gratings ◽  
Single Mode ◽  
Bragg Gratings ◽  
Temperature Sensing ◽  
Direct Writing ◽  
Core Diameter ◽  
Application Range

In this paper, a sapphire-derived fiber (SDF) with a core diameter of 10 μm and a cladding diameter of 125 μm is fabricated by the melt-in-tube method, and fiber Bragg gratings (FBGs) with reflectivity over 80% are prepared by the femtosecond laser point-by-point direct writing method. By analyzing the refractive index distribution and reflection spectral characteristics of the SDF, it can be seen that the SDF is a graded refractive index few-mode fiber. In order to study the element composition of the SDF core, the end-face element distribution of the SDF is analyzed, which indicates that element diffusion occurred between the core and the cladding materials. The temperature and stress of the SDF gratings are measured and the highest temperature is tested to 1000 °C. The temperature and strain sensitivities are 15.64 pm/°C and 1.33 pm/με, respectively, which are higher than the temperature sensitivity of the quartz single-mode fiber. As a kind of special fiber, the SDF expands the application range of sapphire fiber, and has important applications in the fields of high-temperature sensing and high-power lasers.

scholarly journals Highly Reflective Fiber Bragg Gratings Inscribed in Ce/Tm Co-Doped ZBLAN Fibers

2013 ◽  
Vol 25 (11) ◽  
pp. 1066-1068 ◽  
Author(s):  
Mohammed Saad ◽  
Lawrence R. Chen ◽  
Xijia Gu
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Co Doped

Features of Femtosecond Micromachining of Solid Transparent Materials

2021 ◽  
Vol 316 ◽  
pp. 993-998
Author(s):  
Anton S. Chernikov ◽  
Ruslan V. Chkalov
Keyword(s):  
Laser Radiation ◽  
Femtosecond Laser ◽  
Optical Fiber ◽  
Spectral Characteristics ◽  
Fiber Bragg Gratings ◽  
Single Mode ◽  
Bragg Gratings ◽  
Femtosecond Laser Radiation ◽  
Third Order ◽  
Correction System

The paper reports the inscription of second- and third-order fiber Bragg gratings (FBGs) in single-mode optical fiber (SMF-28e+) via the line-by-line (LbL) and the point-by-point (PbP) methods using femtosecond laser radiation. The use of these methods jointly with based on an automatic spatial deviation correction system is considered. The approach allows to significantly improve spectral characteristics of FBG without the loss of fabrication performance.

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