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[Research on the Phase-Shifted Fiber Bragg Grating Spectra under Dynamic Strain Fields]
Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu
|September 27, 2018
Summary
This study explores phase-shifted fiber Bragg gratings (PS-FBGs) for acoustic emission (AE) measurement. Simulations and experiments show PS-FBG spectra change predictably with AE signal characteristics, offering a new sensing approach.
Area of Science:
- Fiber optic sensing
- Acoustic emission measurement
- Materials science
Background:
- Fiber optic sensing is crucial for acoustic emission (AE) measurement in aerospace and geotechnical engineering.
- Traditional fiber Bragg gratings (FBGs) have limitations in AE analysis.
- Phase-shifted fiber Bragg gratings (PS-FBGs) offer potential for enhanced AE sensing.
Purpose of the Study:
- To investigate the spectral response of PS-FBGs under dynamic strain fields generated by AE signals.
- To develop a dynamic strain sensing model for PS-FBGs.
- To analyze the influence of AE signal parameters on PS-FBG spectra.
Main Methods:
- A dynamic strain sensing model for PS-FBGs was developed using transfer matrix theory.
- A cosine exponential attenuation function simulated the dynamic strain field.
- Numerical simulations analyzed the effects of AE signal amplitude, sampling time, attenuation coefficient, frequency, and wavelength.
- Experimental validation was performed using continuous vibration signals.
Main Results:
- PS-FBG spectra exhibit periodic changes with AE signal frequency and sampling time, notably in the transmission window's peak wavelength shift.
- Increased AE signal amplitude leads to more harmonic peaks in the reflected spectrum.
- The attenuation coefficient influences the PS-FBG spectrum within a specific range.
- AE wavelength impacts the PS-FBG spectrum significantly between 0.1 to 2 L.
Conclusions:
- The spectral variations of PS-FBGs under different AE-induced dynamic strain fields follow predictable patterns.
- Experimental results align with simulation findings, confirming the model's validity.
- This research provides theoretical support for developing AE measurement systems based on PS-FBGs.
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