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Guided wave and damage detection in composite laminates using different fiber optic sensors.

Li F, Murayama H, Kageyama K, Shirai T - Sensors (Basel) (2009)

Bottom Line: Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared.The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection.Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

ABSTRACT
Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

No MeSH data available.


Related in: MedlinePlus

FBG-based results. Guided wave signals of the intact (a) and the single-delaminated (b) CFRP laminates. Waveforms (c) of filtered guided wave signals of the intact and the damaged CFRP laminates and their envelopes (d).
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f6-sensors-09-04005: FBG-based results. Guided wave signals of the intact (a) and the single-delaminated (b) CFRP laminates. Waveforms (c) of filtered guided wave signals of the intact and the damaged CFRP laminates and their envelopes (d).

Mentions: In the present study, a Hanning-windowed 5-cycle sinusoidal toneburst [23-25] at a central frequency of 300 kHz was used as incident signal and guided waves were acquired at sampling rate of 4 MHz. Figures 6(a) and (b) depict the FBG-based guided wave signals captured from the intact CFRP laminate and single-delaminated laminate with the delamination length 50 mm, denoted as ‘FBG-Intact’ and ‘FBG-D50-1’, respectively. Compared with the guided wave signal of intact CFRP laminate, noise dominates the signal of the delaminated laminate, because the delamination depresses the energy of the transmitted guided wave. Moreover, it is evident that it is impossible to identify the locus of each wave package in both Figures 6(a) and (b) because of the strong background noise and superposition of neighboring wave packages. Signal processing techniques are therefore required to offer concise features of the guided wave signals. Since the incident signal was a sinusoidal toneburst at a central frequency of 300 kHz, a bandpass filter was selected to depress the influence of noise and Hilbert transform [30-32] was applied to obtain the envelope of each guided wave signal.


Guided wave and damage detection in composite laminates using different fiber optic sensors.

Li F, Murayama H, Kageyama K, Shirai T - Sensors (Basel) (2009)

FBG-based results. Guided wave signals of the intact (a) and the single-delaminated (b) CFRP laminates. Waveforms (c) of filtered guided wave signals of the intact and the damaged CFRP laminates and their envelopes (d).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3297139&req=5

f6-sensors-09-04005: FBG-based results. Guided wave signals of the intact (a) and the single-delaminated (b) CFRP laminates. Waveforms (c) of filtered guided wave signals of the intact and the damaged CFRP laminates and their envelopes (d).
Mentions: In the present study, a Hanning-windowed 5-cycle sinusoidal toneburst [23-25] at a central frequency of 300 kHz was used as incident signal and guided waves were acquired at sampling rate of 4 MHz. Figures 6(a) and (b) depict the FBG-based guided wave signals captured from the intact CFRP laminate and single-delaminated laminate with the delamination length 50 mm, denoted as ‘FBG-Intact’ and ‘FBG-D50-1’, respectively. Compared with the guided wave signal of intact CFRP laminate, noise dominates the signal of the delaminated laminate, because the delamination depresses the energy of the transmitted guided wave. Moreover, it is evident that it is impossible to identify the locus of each wave package in both Figures 6(a) and (b) because of the strong background noise and superposition of neighboring wave packages. Signal processing techniques are therefore required to offer concise features of the guided wave signals. Since the incident signal was a sinusoidal toneburst at a central frequency of 300 kHz, a bandpass filter was selected to depress the influence of noise and Hilbert transform [30-32] was applied to obtain the envelope of each guided wave signal.

Bottom Line: Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared.The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection.Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

ABSTRACT
Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

No MeSH data available.


Related in: MedlinePlus