&lt;title&gt;Fiber optic interferometric strain sensing on composites using an active homodyne sawtooth fringe counting technique&lt;/title&gt;

Schiffer, F.; Fuerstenau, N.; Schmidt, W.

doi:10.1117/12.221116

Cited by 2 publications

(2 citation statements)

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“…Various types of demodulation methods exist to extract strain information from these waveforms. 4,18,[35][36][37][38] An important case in strain measurement using Fabry-Pérot sensors occurs for sinusoidal strain, as occurs in modal testing. 23,24,39,40 The EFPI sensor modulation function is periodic.…”

Section: Efpi Sensor-based Hmssmentioning

confidence: 99%

Demodulation of extrinsic Fabry-Pe´rot interferometric sensors for vibration testing using neural networks

2004

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Strain level measurement on a periodically actuated and instrumented structure can provide information about the health of that structure. A simple demodulation system employing artificial neural networks (ANNs) is analyzed for an extrinsic Fabry-Pé rot interferometric (EFPI) strain sensor. The harmonic content of the nonlinear sensor output for the sinusoidal strain case is used to predict the maximum strain level. Implementations of the demodulation system are demonstrated for both simulated and experimental data using back-propagation neural networks. The simulation uses the theoretical response of the EFPI sensor and the experiment uses an EFPI-instrumented smart composite beam to obtain training and testing data. Excitation is provided by a piezoelectric actuator operating from 50 Hz to 1 kHz. System performance is compared for two-stage and single-stage networks and for differing types of data preprocessing. The ANN systems successfully extract the signal harmonics and predict the peak strain levels. Data preprocessing using principal component analysis produces the best accuracy. The architecture of an EFPI-based health monitoring system is proposed.

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Section: Efpi Sensor-based Hmssmentioning

confidence: 99%

Demodulation of extrinsic Fabry-Pe´rot interferometric sensors for vibration testing using neural networks

2004

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“…At low strain levels, the Fabry-Perot strain sensors have a linear strain to output intensity ratio. However, at high strain levels, they are very non-linear, requiring special demodulation schemes such as fringe counting, phase counting, and white-light interferometery [9,10,11,12]. In this work, a method employing the harmonics of an Extrinsic Fabry-Perot Interferometric (EFPI) signal as calibration points will be described.…”

Section: Introductionmentioning

confidence: 99%

Four-point calibration of PVDF sensor using extrinsic Fabry-Perot interferometric sensors

Abdi

Watkins

2003

SPIE Proceedings

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The performance of sensor systems in smart structures is subject to orientation, installation, and environmental effects. The capability for initial and maintenance calibrations can provide added confidence in sensor information and facilitate investigations of long-term sensor behavior. The use of Extrinsic Fabry-Perot Interferometric (EFPI) fiber-optic sensors was examined for calibration of companion strain sensors. The output of the EFPI sensor is periodic with strain and the signal behavior with periodic strain displays well-defined harmonic content. In particular, the strains giving maximums and minimums in the harmonics can be calculated from the excitation wavelength and the EFPI gage length. A Polyvinylidene Fluoride (PVDF) piezoelectric strain sensor was surface mounted on a cantilever beam and its voltageto-strain ratio was precisely calibrated using the accuracy of a co-located EFPI sensor. The experimental responses of both sensors were obtained for a periodic actuation. The PVDF output was calibrated using a linear-fit of the strains obtained from four points in the harmonic response of the reference EFPI sensor. The selected maximum and minimum points of the EFPI harmonics were directly observed with a spectrum analyzer. This fast, efficient approach was performed under resonant conditions with relatively inexpensive demodulation requirements. The results of the calibration compared well with the expected PVDF response.

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<title>Fiber optic interferometric strain sensing on composites using an active homodyne sawtooth fringe counting technique</title>

Cited by 2 publications

References 3 publications

Demodulation of extrinsic Fabry-Pe´rot interferometric sensors for vibration testing using neural networks

Demodulation of extrinsic Fabry-Pe´rot interferometric sensors for vibration testing using neural networks

Four-point calibration of PVDF sensor using extrinsic Fabry-Perot interferometric sensors

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