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Bidirectional, Bimodal Ultrasonic Lamb Wave Sensing in a Composite Plate Using a Polarization-Maintaining Fiber Bragg
Chunfang Rao1,2, Lingze Duan3
1Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899, USA. rcf0322@jxnu.edu.cn.
Sensors (Basel, Switzerland)
|March 22, 2019
Summary
This study demonstrates a novel polarization-maintaining fiber Bragg grating (PM-FBG) sensor for bidirectional Lamb wave (LW) detection in composites. The sensor effectively distinguishes wave modes and propagation directions for advanced structural health monitoring (SHM).
Area of Science:
- Materials Science and Engineering
- Structural Health Monitoring (SHM)
- Wave Propagation in Anisotropic Media
Background:
- Lamb waves (LWs) are suitable for SHM in advanced composites, but mode (symmetric/anti-symmetric) and material anisotropy complicate detection.
- Direction-sensitive sensing is crucial for composite materials due to their inherent anisotropy.
- Existing SHM methods face challenges in differentiating LW modes and propagation directions.
Purpose of the Study:
- To experimentally demonstrate bidirectional, bimodal (S0 and A0) LW measurement using a polarization-maintaining fiber Bragg grating (PM-FBG) sensor.
- To show the capability of a PM-FBG sensor to differentiate LW propagation directions (0° and 90°).
- To explore the potential of PM-FBGs as versatile multi-parameter SHM detectors for composite structures.
Main Methods:
- Utilized a polarization-maintaining fiber Bragg grating (PM-FBG) sensor attached to a composite laminated plate.
- Conducted bidirectional (0° and 90°) and bimodal (S0 and A0) LW measurements in the 20–140 kHz frequency range.
- Selectively interrogated the fast and slow axes of the PM-FBG to analyze sensor responses.
Main Results:
- The PM-FBG sensor successfully detected LWs propagating in both 0° and 90° directions.
- Selective interrogation of PM-FBG axes allowed differentiation of LW propagation directions.
- The fast axis responded to both S0 and A0 modes when aligned with propagation, while the slow axis showed single S0 mode response perpendicular to propagation.
Conclusions:
- PM-FBG sensors offer a versatile solution for multi-parameter SHM in advanced composites.
- The sensor effectively addresses challenges posed by material anisotropicity and LW mode diversity.
- This technology holds significant potential for enhancing the reliability and capability of SHM systems.
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