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Name of Experiment: application of power amplifier in Fiber grating sensing composite detection

Research Direction：grating sensing composite detection

Experiment Contents: the influence of frequency, phase, amplitude, position and other factors of two excitation sources on FBG response characteristics is mainly studied to provide a parameter basis for subsequent damage localization.

Experiment Equipment: signal generator, ATA-2041 power amplifier, tunable laser source, oscilloscope, photodetector

Experiment Process: build multi-source excitation detection system: The detection system scheme of multi-source excitation and fiber grating sensing based on isotropic plate structure is shown in the figure, which mainly includes excitation part and FBG demodulation part. Excitation part includes signal generator, high voltage amplifier (ATA-2041), FBG demodulation part mainly includes broadband coupler, adjustable laser light source, photodetector, oscilloscope.Channel 1 of signal generator is directly applied on the piezoelectric patches, using high voltage amplifier to amplify, channel 2 is imposed on piezoelectric film after amplification, using the inverse piezoelectric effect, strain waves in the plate structure, the response is received by FBG sensor, and after demodulation, it is converted from photodetector to electrical signal, which is displayed on oscilloscope.

Experiment Result：

(1)Excitation size parameter   

In the case of the same parameters of component thickness and excitation amplitude, the larger the diameter, the larger the response amplitude, so to get a larger response amplitude, the size with a larger diameter can be appropriately selected.

The excitation effect under different size

（2）Under the same excitation condition, the FBG sensing response effect at different positions is compared, as shown in the figure. Since excitation A is along the axis of #1FBG, the black curve under excitation A in Figure A has a larger response. Similarly, since excitation C is along the axis of #2FBG, the red curve in Figure B, which represents the response of excitation C, is relatively large. It can be seen that no matter #1FBG or #2FBG, the response effect is better if it is directly against the detection position of the excitation element.

FBG response curves at different locations

The performance of the amplifier in the experiment: amplify the voltage, excite the piezoelectric plate