# US 2019/0170697 A1 · Distributed sensing fiber acoustic emission apparatus and method for monitoring hydraulic engineering safety behavior

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- Number: US 2019/0170697 A1
- Document ID: US20190170697A1
- Status: Published application
- Kind: A1
- Application number: 15/831,469
- Filed: 2017-12-05
- Published: 2019-06-06
- Earliest claimed: 2017-12-05
- Assignees: Hohai University
- Applicants: Hohai University
- Inventors: Huaizhi Su; Meng Yang
- Web page: https://patentgrep.com/patent/US20190170697A1

## CPC

- G01N 29/14: using acoustic emission techniques {(echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00)}
- G01N 29/221: {Arrangements for directing or focusing the acoustical waves (electronic orientation or focusing G01N29/262; sound directing or focusing G10K11/26; mechanical steering of sound transducers or their beams G10K11/35)}
- G01N 29/225: {Supports, positioning or alignment in moving situation}
- G01N 29/2418: {using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics (photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046)}
- G01H 9/004: {using fibre optic sensors (light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125)}
- G01N 2291/0232: Glass, ceramics, concrete or stone
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES

## Abstract

A distributed sensing fiber acoustic emission apparatus and method for monitoring a hydraulic engineering safety behavior includes a fiber-carrying laying module and a fiber acoustic emission module. The fiber-carrying laying module includes an inner supporter, mesh modules and fiber-carrying modules, the inner supporter, the mesh modules and the fiber-carrying modules form a cylindrical shape. The cross section of the inner supporter is in a quadrangle inner-concave shape with the four edges concaved, the four surfaces of the inner supporter are concaved, the mesh modules having a plurality of meshes are respectively disposed in the four concave surfaces of the inner supporter, and the fiber-carrying module is arranged between every two adjacent mesh modules.

## Claims

### Claim 1

A distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior, comprising a fiber-carrying laying module and a fiber acoustic emission module, wherein the fiber-carrying laying module comprises an inner supporter, mesh modules and fiber-carrying modules, the inner supporter, the mesh modules and the fiber-carrying modules form a cylindrical shape, the cross section of the inner supporter is in a quadrangle inner-concave shape with the four edges concaved, the four surfaces of the inner supporter are concaved, the mesh modules having a plurality of meshes are respectively disposed in the four concave surfaces of the inner supporter, and the fiber-carrying module is arranged between every two adjacent mesh modules; and
the fiber acoustic emission module comprises a driving power source, a mode-locked laser, a femtosecond laser optical frequency comb, a pulse modulator, a wavelength division multiplexer, an optical path coupler, an amplifier, a receiver, a detector, a controller, a concrete structure safety behavior evaluation system, an acoustic emission signal, a Rayleigh optical receiver, a Brillouin optical receiver, and an optical splitter, the output end of the driving power source is connected with the input end of the mode-locked laser, the input end of the driving power source is connected with the output end of the controller, the mode-locked laser is connected with the femtosecond laser optical frequency comb, the pulse modulator and the wavelength division multiplexer in sequence, the output end of the wavelength division multiplexer is respectively connected with the input end of the optical splitter and the input end of the optical path coupler, the output end of the optical splitter is respectively connected with the input end of the Rayleigh optical receiver and the input end of the Brillouin optical receiver, the output end of the Rayleigh optical receiver and the output end of the Brillouin optical receiver are connected with the input end of the controller, the output end of the optical path coupler is connected with the input end of the amplifier and the input end of the receiver, and output end of the receiver is connected with the input end of the detector, the output end of the detector is connected with the input end of the controller, the output end of the amplifier is connected with a sensing fiber in the fiber-carrying laying module, and the output end of the controller is connected with the concrete structure safety behavior evaluation system.

### Claim 2 (depends on 1)

The distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior according to claim 1, wherein the mesh module comprises a carrier, the carrier is provided with meshes along an axis of the sensing fiber, each carrier is provided with one of a triangle common cavity mesh, a circular common cavity mesh, a quadrangle common cavity mesh and a pentagon common cavity mesh, the shapes of the meshes the carriers are different, and the triangle common cavity mesh, the circular common cavity mesh, the quadrangle common cavity mesh and the pentagon common cavity mesh are arranged in an anticlockwise order.

### Claim 3 (depends on 2)

The distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior according to claim 2, wherein the fiber-carrying module comprises a barrier block, sealing plugs, a double-fiber channel and a semicircular fiber bearing platform, the semicircular fiber bearing platform is connected with the carrier and is internally provided with the double-fiber channel, the double-fiber channel is internally provided with two sensing fibers, the two sides of the top of the semicircular fiber bearing platform are respectively hinged with the sealing plug, and the two sealing plugs are locked through the barrier block.

### Claim 4 (depends on 3)

The distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior according to claim 3, wherein the semicircular fiber bearing platform is internally provided with a fiber separation wall for separating the two sensing fibers.

### Claim 5 (depends on 4)

The distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior according to claim 4, wherein the fiber separation wall is a vacuum insulation panel.

### Claim 6 (depends on 5)

The distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior according to claim 5, further comprising a converter connection module, wherein the converter connection module comprises a first base and a second base, the first base is connected with a fold shaft epitaxial column through a first lantern ring, the second base is connected with the fold shaft epitaxial column through a second lantern ring, both the first lantern ring and the second lantern ring are provided with a locking apparatus, the upper end of the first base is provided with a first fiber-carrying bending hole, the upper end of the second base is provided with a second fiber-carrying bending hole, the fold shaft epitaxial column is provided with an inner through hole, the inner through hole is internally provided with a bending folded shaft, and the upper end surface of the bending folded shaft is provided with a fixing plug.

### Claim 7 (depends on 6)

A running method of the distributed sensing fiber acoustic emission apparatus for monitoring hydraulic engineering safety behavior according to claim 6, comprising:
first step: establishing the distributed sensing fiber acoustic emission apparatus for monitoring a hydraulic engineering safety behavior composed of the fiber acoustic emission module, the converter connection module and the fiber-carrying laying module, removing the barrier block, rotating the sealing plugs at the two sides around the bending folded shaft, arranging eight sensing fibers in four double-fiber channel in pairs, closing the sealing plugs at the two sides around the bending folded shaft, pressing a joint of the sealing plugs, passing the barrier block through the upper end of the fiber separation wall, and fixing the closing parts of the sealing plugs at the two sides;
second step: placing a component formed by the mesh modules and the fiber-carrying modules in the first fiber-carrying bending hole and the second fiber-carrying bending hole at the possibly bent position of the fiber-carrying laying module, rotating the bending folded shaft according to engineering demands, so as to drive the rotation of the first base and the second base, thus forming a certain included angle between the first fiber-carrying bending hole and the second fiber-carrying bending hole, and then inserting the fixing plug into the bending folded shaft, and fixing the bending folded shaft, thus fixing the angle between the first fiber-carrying bending hole and the second fiber-carrying bending hole;
third step: opening each component in the fiber acoustic emission module, and starting the driving power source through controlling the controller, thus stimulating the mode-locked laser to generate the femtosecond laser optical frequency comb, and modulating the femtosecond laser optical frequency comb through the pulse modulator, the wavelength division multiplexer and the optical splitter; and
fourth step: generating the acoustic emission signal when some part of the structure to be monitored is damaged, the acoustic emission signal transmitted through the pentagon common cavity mesh, the triangle common cavity mesh, the circular common cavity mesh and the quadrangle common cavity mesh being transduced into the sensing fiber of the fiber-carrying laying module according to different time and frequencies, and Rayleigh scattering light information and Brillouin scattering light information in the sensing fiber being affected, receiving and detecting the femtosecond laser optical frequency comb of the changed Rayleigh scattering light information and the changed Brillouin scattering light information through the Rayleigh optical receiver and the Brillouin optical receiver, then collecting the information into the concrete structure safety behavior evaluation system through the controller for analysis and research, and evaluating and analyzing the information like the damaged position and degree of the structure.