A three-dimensional monitoring substrate type fiber grating crack sensor and its dynamic analysis method

Abstract

The invention discloses a three-dimensional monitoring substrate type fiber Bragg grating crack sensor and a dynamic analysis method thereof. The three-dimensional monitoring substrate type fiber Bragg grating crack sensor can monitor the set X, Y, and Z three-dimensional displacements of a measured surface respectively, and the three-dimensional monitoring data are monitored independently without interfering with each other; the three-dimensional monitoring substrate type fiber Bragg grating crack sensor is fixed on a relatively fixed surface, and a monitoring auxiliary tooling is fixed on the monitored surface, and an initial data model is established by mapping the three-dimensional relative positions of the relatively fixed surface and the monitored surface; the XYZ displacement of the detected surface is dynamically monitored in real time, and the X, Y, and Z three-dimensional displacement dynamic curves are respectively drawn in real time, and the data is imported into the dynamic model, and the displacement change is displayed in real time, and the historical change can be recorded. Therefore, the dynamic analysis method is intuitive and efficient in observing the displacement change, and can effectively provide a basis for structural health diagnosis.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber grating sensors, and in particular relates to a three-dimensional monitoring substrate type fiber grating crack sensor and a dynamic analysis method thereof. Background Art

[0002] Displacement is one of the most important and basic physical quantities that needs to be monitored in various fields, and it plays a vital role in the completion of various projects. Traditional displacement monitoring devices can only monitor displacement in one direction. If the monitoring position has large, multi-directional staggered displacement changes, traditional displacement monitoring devices will not only fail to monitor effectively, but will also damage the sensor and distort the monitoring data.

[0003] Fiber Bragg grating sensor is a wavelength modulated fiber optic sensor. The basic working principle is that light enters the grating area through the optical fiber, and through the change of external quantity, it causes multiple parameters of light in the grating area to change, such as wavelength, intensity, amplitude, frequency, etc., so as to measure the external quantity and realize data transmission. Fiber Bragg grating sensor has the characteristics of strong anti-interference ability, no electromagnetic interference, high measurement accuracy, easy distributed networking, good environmental adaptability, etc. Fiber Bragg grating sensor is a safety product, widely used in remote, online, real-time, intelligent monitoring of mines, bridges, tunnels, deep foundation pits, high slopes, prefabricated buildings, etc.

[0004] At present, domestic and foreign manufacturers engaged in fiber grating sensing technology generally use epoxy resin, fiber grating and sensor matrix to encapsulate the substrate. The epoxy resin glue is only combined with the sensor matrix through physical bonding. The bonding method is not strong and the epoxy resin glue is easily damaged and falls off in high temperature, high humidity, strong ultraviolet rays and corrosive environments, which needs further improvement. Summary of the invention

[0005] The present invention provides a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor and a dynamic analysis method thereof, which can solve the problem that a traditional displacement monitoring device cannot realize the monitoring of multi-directional displacement. For example, if a monitoring position produces a large, multi-directional staggered displacement change, a traditional displacement monitoring device not only cannot effectively monitor it, but also damages the sensor and distorts the monitoring data. A single-axis displacement sensing detection device can only display a time-displacement change curve and cannot dynamically display a three-dimensional change. Conventional fiber Bragg grating sensors have poor durability and stability. The above problems largely limit the application and promotion of fiber Bragg grating displacement sensors.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] The embodiment of the present invention provides a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor, which comprises a housing (1), a connecting rod driving device (2), an external connecting rod (3), a fiber Bragg grating spring monitoring device (4), a fiber Bragg grating demodulation and analysis system (5), and a monitoring auxiliary tooling (6);

[0008] The housing (1) comprises a base (101) and a protective cover (102), wherein the protective cover (102) is connected to the base (101) via bolts; a plurality of mounting partitions (101-1) are arranged inside the base (101) for mounting a plurality of connecting rod driving devices (2), a plurality of external connecting rods (3) and a plurality of fiber grating shrapnel monitoring devices (4);

[0009] The monitoring auxiliary tooling (6) is in the form of three-sided coordinate axes, namely, an XY horizontal plane structure, a ZX horizontal front structure, and a YZ vertical side structure, wherein the XY horizontal plane structure is used to detect the displacement change in the Z-axis direction, the ZX horizontal front structure is used to detect the displacement change in the Y-axis direction, and the YZ vertical side structure is used to detect the displacement change in the X-axis direction;

[0010] Each of the external connecting rods (3) comprises a connecting rod (301), an extension rod (302), an elbow (303) and a universal ball bearing contact rod (304) which are connected in sequence; the universal ball bearing contact rods 304 of the plurality of external connecting rods (3) respectively contact the XY horizontal plane structure, the ZX transverse front structure and the YZ vertical side structure, and slide flexibly on the surfaces thereof to ensure that they are only affected by single-axis displacement; during the monitoring process, the plurality of external connecting rods (3) do not affect each other, and the plurality of external connecting rods (3) are connected to the drive accessory mounting seat (201) of the connecting rod driving device (2);

[0011] The optical fiber (406) of the optical fiber Bragg grating shrapnel monitoring device (4) is led to the optical fiber Bragg grating demodulation and analysis system (5). After the optical fiber Bragg grating demodulation and analysis system (5) demodulates the wavelength of the optical fiber (406), the analyzed data is sent to a remote cloud platform via a wireless communication module, thereby realizing local and remote real-time online monitoring.

[0012] According to an optional embodiment of the present invention, the connecting rod driving device (2) comprises a driving accessory mounting seat (201), a driving slider (202), a driving guide rod (203), a spring guide column (204) and a spring (205);

[0013] The drive accessory mounting seat (201) is fixed on the drive slider (202), and the drive slider (202) drives the drive accessory mounting seat (201) to flexibly move linearly on the drive guide rod (203), and the drive guide rod (203) is fixed on the housing (1); a spring baffle (201-1) is provided on the drive accessory mounting seat (201), and a first through hole (201-2) is provided on the spring baffle (201-1), and the spring guide column (204) passes through the first through hole (201-2), and the spring guide column (204) is fixed on the housing (1), and the spring guide column (204) is wound with the spring (205); one end of the spring (205) presses the housing (1), and the other end presses on the drive accessory mounting seat (201), so as to transmit the elastic force to the external connecting rod (3), so as to ensure that the external connecting rod (3) is always pressed against the monitoring auxiliary tooling (6).

[0014] According to an optional embodiment of the present invention, the connecting rod driving device (2) comprises a vertical rod guide sleeve (207), a transmission connecting rod (208) and a fixed shaft seat (209);

[0015] The side surface of the driving accessory mounting seat (201) is connected to a first driving vertical rod (206-1) at an axially vertical position of the driving guide rod (203); one end of the driving guide rod (203) is vertically connected to a second driving vertical rod (206-2); the first driving vertical rod (206-1) is sleeved with a first vertical rod guide sleeve (207-1); the second driving vertical rod (206-2) is sleeved with a second vertical rod guide sleeve (207-2); the side surface of the second vertical rod guide sleeve (207-2) is connected to a first circular shaft (207-3);

[0016] The first circular shaft (207-3) is embedded in the driving hole (208-1) of the transmission connecting rod (208); the transmission connecting rod (208) is a long plate-shaped structure; a fixed shaft hole (208-2) is opened in the middle of the transmission connecting rod (208); the fixed shaft seat (209) is fixed on the housing (1); the fixed shaft seat (209) is provided with the fixed shaft (209-1); the fixed shaft (209-1) passes through the fixed shaft hole ( The transmission connecting rod (208) is provided with a transmission hole (208-3) at the other end of the transmission connecting rod (208), and the distance from the transmission hole (208-3) to the fixed shaft hole (208-2) and the distance from the driving hole (208-1) to the fixed shaft hole (208-2) are in a preset ratio.

[0017] According to an optional embodiment of the present invention, the connecting rod driving device (2) further comprises a driven vertical rod (210), a driven accessory mounting seat (211), a driven slider (212) and a driven guide rod (213); wherein the driven guide rod (213) is fixed on the base (101), the driven slider (212) is movably mounted on the driven guide rod (213), the driven accessory mounting seat (211) is mounted on the driven slider (212), the driven accessory mounting seat 211 is mounted on the driven vertical rod (210), a third vertical rod guide sleeve (207-4) is sleeved on the driven vertical rod (210), and the driven slider (212) drives the driven accessory mounting seat (211) to flexibly move linearly on the driven guide rod (213).

[0018] According to an optional embodiment of the present invention, the fiber Bragg grating spring monitoring device (4) comprises a substrate guide column (401), a fiber Bragg grating spring (402), a substrate pressing plate (403), a substrate fixing seat (404) and a fiber Bragg grating temperature compensation substrate (405);

[0019] The transmission connecting rod 208 transmits the displacement to the driven accessory mounting seat (211) according to a preset ratio; the inclined surface 211-1 at the top of the driven accessory mounting seat (211) contacts the substrate guide post (401), and the substrate guide post (401) passes through the outside of the fiber grating spring piece (402) to ensure that it moves in an axial straight line and limits its radial displacement and rotation; the inclined surface (211-1) transmits the displacement movement to the fiber grating spring piece (402) through the substrate guide post (401) according to a preset ratio;

[0020] The fiber grating spring piece (402) is fixed on the substrate fixing seat (404) through a substrate pressing plate (403); the substrate fixing seat (404) is fixedly connected to the base (101); the fiber grating temperature compensation substrate (405) is respectively fixed between the fiber grating spring piece (402) and the substrate pressing plate (403); the fiber grating spring piece (402) and the fiber grating temperature compensation substrate (405) are connected in series in the base (101).

[0021] According to an optional embodiment of the present invention, the driving guide rod (203), the spring guide column (204), the first driving vertical rod (206-1), the second driving vertical rod (206-2), the driven vertical rod (210) and the driven guide rod (213) are all rod-shaped structures with the same cross-section.

[0022] According to an optional embodiment of the present invention, the cross-section of the external connecting rod (3) is a square structure, which is used to reduce its elastic deformation, and the universal ball bearing is installed at the end of the universal ball bearing contact rod (304).

[0023] The embodiment of the present invention further provides a dynamic analysis method for a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor, wherein the dynamic analysis method is implemented by a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor in the above embodiment, wherein the dynamic analysis method comprises the following steps:

[0024] Step S1, fix the three-dimensional monitoring substrate-type fiber Bragg grating crack sensor on a relatively fixed surface, and fix the monitoring auxiliary tooling on the monitored surface; compress the external connecting rods for X, Y, and Z axis monitoring to the middle position of the stroke to ensure that the measurable positive and negative displacement range is maximized;

[0025] Step S2, the optical fiber (406) of the fiber Bragg grating shrapnel monitoring device (4) is led to the fiber Bragg grating demodulation and analysis system (5), the relative fixed surface and the monitored surface are mapped, and an initial plane data model Ax+By+Cz+D=0 is established with a point on the relative fixed surface as the origin;

[0026] Step S3, the three-dimensional monitoring substrate-type fiber Bragg grating crack sensor performs real-time dynamic monitoring of the X, Y, and Z displacements of the monitored surface, demodulates and analyzes the wavelength data, obtains the displacement change (a, b, c), saves the monitoring data, and draws the X, Y, and Z three-dimensional displacement dynamic curves in real time;

[0027] Step S4, obtaining a normal vector n: (x, y, z) based on the displacement change in the rated time period, and obtaining different-stage plane data models A1x+B1y+C1z+D=0, A2x+B2y+C2z+D=0, ...;

[0028] Step S5, the fiber Bragg grating demodulation and analysis system (5) sets the over-limit angle and displacement limit thresholds, establishes a dynamic model to display the displacement change in real time, and sends the data to the remote cloud platform through the wireless communication module, so as to realize local and remote real-time online monitoring.

[0029] Compared with the prior art, the embodiment of the present invention provides a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor and a dynamic analysis method thereof, which has the following beneficial effects:

[0030] (1) Chinese patent CN112230327A discloses "an all-glass packaging device and packaging method for fiber Bragg gratings". The present invention is based on the patent technology and innovatively develops a new fiber Bragg grating sensor substrate, which solves the problems of poor durability and stability of current fiber optic sensors. The three-dimensional monitoring substrate fiber Bragg grating crack sensor can monitor the set X, Y, and Z three-dimensional displacements of the measured surface respectively, and the three-dimensional monitoring data are independently monitored without interfering with each other. It can establish a dynamic model based on the initial surveying and mapping mathematical model to display its displacement changes in real time.

[0031] (2) Three-dimensional monitoring substrate-type fiber Bragg grating crack sensor The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor is fixed on a relatively fixed surface, and the monitoring auxiliary tooling is fixed on the monitored surface. The three-dimensional relative position of the relatively fixed surface and the monitored surface is mapped to establish an initial data model. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor performs real-time dynamic monitoring of the XYZ displacement of the detected surface, and draws the X, Y, and Z three-dimensional displacement dynamic curves in real time. The data is imported into the dynamic model control to display the displacement changes in real time and record the historical changes. Observing the displacement changes is intuitive and efficient, and can effectively provide a basis for structural health diagnosis.

[0032] (3) The driving guide rod 203, spring guide column 204, driving vertical rod, driven vertical rod 210, driven guide rod 213, and substrate guide column 401 in the present invention have a matching accuracy of no less than H6h5, which ensures the sliding flexibility while ensuring the synchronization and consistency of the drive, and avoids the precision error caused by the gap to the greatest extent.

[0033] (4) The driving hole 208-1, the fixed shaft hole 208-2 and the transmission hole 208-3 of the transmission connecting rod in the present invention are all equipped with high-precision bearings to limit its axial displacement while ensuring its flexible rotation and controllable clearance; and the transmission is carried out in proportion to effectively reduce the size of the sensor and make full use of the internal space of the base 101.

[0034] (5) The inclined surface 211-1 is ground using a substrate spring to press the substrate guide post 401 to contact the inclined surface 211-1, thereby reducing the impact of the starting gap and processing tolerance on the accuracy; and the center plane of the inclined surface 211-1 can be fixed at a certain angle to the center plane of the driven accessory mounting seat 211, providing a larger turning radius for optical fiber layout and reducing optical loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic structural diagram of a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor provided in an embodiment of the present application.

[0037] Figure 2 A schematic diagram of the internal structure of a shell of a three-dimensional monitoring substrate-type fiber grating crack sensor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0039] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a structural schematic diagram of a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor includes a housing 1, a connecting rod driving device 2, an external connecting rod 3, a fiber Bragg grating spring monitoring device 4, a fiber Bragg grating demodulation and analysis system 5, and a monitoring auxiliary tooling 6.

[0040] The housing 1 includes a base 101 and a protective cover 102, and the protective cover 102 is connected to the base 101 by bolts; the base 101 is provided with a plurality of mounting partitions 101-1 for mounting a plurality of connecting rod driving devices 2, a plurality of external connecting rods 3 and a plurality of fiber grating shrapnel monitoring devices 4.

[0041] The monitoring auxiliary tooling 6 is a three-sided coordinate axis style, namely an XY horizontal plane structure, a ZX horizontal front structure and a YZ vertical side structure. The XY horizontal plane structure is used to detect the displacement change in the Z-axis direction, the ZX horizontal front structure is used to detect the displacement change in the Y-axis direction, and the YZ vertical side structure is used to detect the displacement change in the X-axis direction.

[0042] Each external connecting rod 3 includes a connecting rod 301, an extension rod 302, an elbow 303 and a universal ball bearing contact rod 304 connected in sequence, wherein the above accessories are fixed in double layers by bolt slots. The universal ball bearing contact rods 304 of multiple external connecting rods 3 contact the XY horizontal plane structure, the ZX horizontal front structure and the YZ vertical side structure respectively, and slide flexibly on their surfaces to ensure that they are only affected by single-axis displacement; during the monitoring process, multiple external connecting rods 3 do not affect each other, and multiple external connecting rods 3 are connected to the drive accessory mounting seat 201 of the connecting rod driving device 2. The cross-section of the external connecting rod 3 in this embodiment is a square structure, which is used to reduce its elastic deformation, and a universal ball bearing is installed at the end of the universal ball bearing contact rod 304.

[0043] The optical fiber 406 of the fiber grating shrapnel monitoring device 4 is exported to the fiber grating demodulation and analysis system 5. After the fiber grating demodulation and analysis system 5 demodulates the wavelength of the optical fiber 406, the analyzed data is sent to the remote cloud platform through the wireless communication module, so as to realize local and remote real-time online monitoring.

[0044] The connecting rod driving device 2 includes a driving accessory mounting seat 201, a driving slider 202, a driving guide rod 203, a spring guide column 204 and a spring 205. The driving accessory mounting seat 201 is fixed on the driving slider 202, and the driving slider 202 drives the driving accessory mounting seat 201 to flexibly move linearly on the driving guide rod 203, and the driving guide rod 203 is fixed on the housing 1; a spring baffle 201-1 is provided on the driving accessory mounting seat 201, and a first through hole 201-2 is provided on the spring baffle 201-1, and a spring guide column 204 is arranged through the first through hole 201-2, and the spring guide column 204 is fixed on the housing 1, and the spring guide column 204 is wound with a spring 205; one end of the spring 205 presses the housing 1, and the other end presses on the driving accessory mounting seat 201, and transmits the elastic force to the external connecting rod 3, ensuring that the external connecting rod 3 is always pressed against the monitoring auxiliary tooling 6.

[0045] The connecting rod driving device 2 includes a transmission connecting rod 208 and a fixed shaft seat 209; wherein, the side of the driving accessory mounting seat 201 is connected to a first driving vertical rod 206-1 at an axially vertical position of the driving guide rod 203, and one end of the driving guide rod 203 is vertically connected to a second driving vertical rod 206-2, and the first driving vertical rod 206-1 is sleeved with a first vertical rod guide sleeve 207-1, and the second driving vertical rod 206-2 is sleeved with a second vertical rod guide sleeve 207-2. The vertical rod guide sleeve can flexibly move linearly on the driving vertical rod; the second vertical rod guide sleeve 207-2 is connected to a first round shaft 207-3 on the side. The first round shaft 207-3 is embedded in the driving hole 208-1 of the transmission connecting rod 208. The transmission connecting rod 208 is a long plate-like structure; a fixed shaft hole 208-2 is opened in the middle of the transmission connecting rod 208; the fixed shaft seat 209 is fixed on the outer shell 1, and the fixed shaft seat 209 is provided with a fixed shaft 209-1; the fixed shaft 209-1 is set through the fixed shaft hole 208-2, connecting the transmission connecting rod 208 to the base 101, and the transmission connecting rod 208 can be flexibly rotated radially around the fixed shaft 209-1; a transmission hole 208-3 is set at the other end of the transmission connecting rod 208, and the distance from the transmission hole 208-3 to the fixed shaft hole 208-2 is in a preset ratio with the distance from the drive hole 208-1 to the fixed shaft hole 208-2.

[0046] The connecting rod driving device 2 also includes a driven vertical rod 210, a driven accessory mounting seat 211, a driven slider 212 and a driven guide rod 213; wherein the driven guide rod 213 is fixed on the base 101, the driven slider 212 is movably mounted on the driven guide rod 213, the driven accessory mounting seat 211 is mounted on the driven slider 212, the driven accessory mounting seat 211 is mounted on the driven vertical rod 210, the driven vertical rod 210 is sleeved with a third vertical rod guide sleeve 207-4, and the driven slider 212 drives the driven accessory mounting seat 211 to flexibly move linearly on the driven guide rod 213.

[0047] The driving guide rod 203, the spring guide column 204, the first driving upright rod 206-1, the second driving upright rod 206-2, the driven upright rod 210, and the driven guide rod 213 are all rod-shaped structures with the same cross-section.

[0048] The fiber grating shrapnel monitoring device 4 includes a substrate guide column 401, a fiber grating shrapnel 402, a substrate pressure plate 403, a substrate fixing seat 404 and a fiber grating temperature compensation substrate 405; wherein, the transmission connecting rod 208 transmits the displacement amount to the driven accessory mounting seat 211 according to a preset ratio; the inclined surface 211-1 at the top of the driven accessory mounting seat 211 contacts the substrate guide column 401, and the substrate guide column 401 passes through the outside of the fiber grating shrapnel 402 to ensure its axial linear motion and limit its radial displacement and rotation; the inclined surface 211-1 transmits the displacement motion amount to the fiber grating shrapnel 402 through the substrate guide column 401 according to a preset ratio.

[0049] The fiber grating shrapnel 402 is fixed on the substrate fixing seat 404 through the substrate pressing plate 403; the substrate fixing seat 404 is fixed to the base 101; the fiber grating temperature compensation substrate 405 can be fixed between any fiber grating shrapnel 402 and the substrate pressing plate 403 respectively, and the three axes share one fiber grating temperature compensation substrate 405; the XYZ three-axis monitoring all adopts the same structure cross distribution; the fiber grating shrapnel 402 and the fiber grating temperature compensation substrate 405 are connected in series in the base 101, and are exported to the fiber grating demodulation and analysis system 5 through the optical fiber 406. After the fiber grating demodulation and analysis system 5 demodulates the wavelength, the analyzed data is sent to the remote cloud platform through the wireless communication module, so that local and remote real-time online monitoring can be realized.

[0050] The truncated cone 401-1 of the substrate guide post 401 passes through the substrate spring and contacts the inclined surface 211-1 to ensure that it is in close contact with the inclined surface 211-1; the straight tip 401-2 at the top of the substrate guide post 401 contacts the fiber grating spring 402. The fiber grating temperature compensation substrate 405 and the fiber grating spring 402 are both sheet structures, fixed to the substrate pressing plate 403 and the substrate fixing seat 404 by threads, and the substrate fixing seat 404 is preferably an L-shaped structure.

[0051] The embodiment of the present invention further provides a dynamic analysis method for a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor, wherein the dynamic analysis method is implemented by a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor in the above embodiment, wherein the dynamic analysis method comprises the following steps:

[0052] Step S1, fix the three-dimensional monitoring substrate-type fiber Bragg grating crack sensor on a relatively fixed surface, and fix the monitoring auxiliary tooling on the monitored surface; compress the external connecting rods for X, Y, and Z axis monitoring to the middle position of the stroke to ensure that the measurable positive and negative displacement range is maximized;

[0053] Step S2, the optical fiber 406 of the fiber Bragg grating shrapnel monitoring device 4 is led to the fiber Bragg grating demodulation and analysis system 5, the relative fixed surface and the monitored surface are mapped, and an initial plane data model Ax+By+Cz+D=0 is established with a point on the relative fixed surface as the origin;

[0054] Step S3, the three-dimensional monitoring substrate-type fiber Bragg grating crack sensor performs real-time dynamic monitoring of the X, Y, and Z displacements of the monitored surface, demodulates and analyzes the wavelength data to obtain the displacement changes a, b, and c, saves the monitoring data, and draws the X, Y, and Z three-dimensional displacement dynamic curves in real time;

[0055] Step S4, obtaining the normal vector n: x, y, z according to the displacement change in the rated time period, and obtaining the plane data models of different stages A1x+B1y+C1z+D=0, A2x+B2y+C2z+D=0, ... respectively;

[0056] Step S5, the fiber Bragg grating demodulation and analysis system 5 sets the over-limit angle and displacement limit thresholds, establishes a dynamic model to display the displacement change in real time, and sends the data to the remote cloud platform through the wireless communication module, so as to realize local and remote real-time online monitoring.

[0057] In one embodiment, the driving guide rod 203, the driving vertical rod, the driven vertical rod 210, the driven guide rod 213 and their supporting sliding mechanisms can be replaced with sliding modes such as guide rail sliders, linear bearing optical axes, etc. In another embodiment, the XYZ axis layout can be set by itself to facilitate flexible adjustment of the monitoring direction, not limited to the example process.

[0058] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to them. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered within the protection scope of the present invention. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be based on the scope defined by the claims.

Claims

1. A three-dimensional monitoring substrate-type fiber Bragg grating crack sensor, characterized in that: It comprises a housing (1), a connecting rod driving device (2), an external connecting rod (3), a fiber optic Bragg grating shrapnel monitoring device (4), a fiber optic Bragg grating demodulation and analysis system (5), and a monitoring auxiliary tooling (6); The housing (1) comprises a base (101) and a protective cover (102), wherein the protective cover (102) is connected to the base (101) via bolts; a plurality of mounting partitions (101-1) are arranged inside the base (101) for mounting a connecting rod driving device (2), an external connecting rod (3) and a fiber optic grating shrapnel monitoring device (4); The monitoring auxiliary tooling (6) is in the form of a three-sided coordinate axis, namely an XY horizontal plane structure, a ZX horizontal front structure and a YZ vertical side structure, wherein the XY horizontal plane structure is used to detect the displacement change in the Z-axis direction, the ZX horizontal front structure is used to detect the displacement change in the Y-axis direction, and the YZ vertical side structure is used to detect the displacement change in the X-axis direction; Each of the external connecting rods (3) comprises a connecting rod (301), an extension rod (302), an elbow (303) and a universal ball bearing contact rod (304) which are connected in sequence; the universal ball bearing contact rod 304 of the external connecting rod (3) contacts the XY horizontal plane structure, the ZX transverse front structure and the YZ vertical side structure respectively, and slides flexibly on the surfaces thereof to ensure that it is only affected by single-axis displacement; during the monitoring process, the external connecting rods (3) do not affect each other, and the external connecting rods (3) are connected to the drive accessory mounting seat (201) of the connecting rod driving device (2); The fiber grating shrapnel monitoring device (4) comprises a substrate guide column (401), a fiber grating shrapnel (402), a substrate pressing plate (403), a substrate fixing seat (404) and a fiber grating temperature compensation substrate (405); wherein the transmission connecting rod (208) of the connecting rod driving device (2) transmits the displacement amount to the driven accessory mounting seat (211) according to a preset ratio; the inclined surface (211-1) at the top of the driven accessory mounting seat (211) contacts the substrate guide column (401), and the substrate guide column (401) passes through the outside of the fiber grating shrapnel (402) to ensure that it moves in an axial straight line and restricts its radial displacement and rotation; the inclined surface (211-1) transmits the displacement amount to the fiber grating shrapnel (402) through the substrate guide column (401) according to a preset ratio; The fiber grating spring piece (402) is fixed on the substrate fixing seat (404) via a substrate pressing plate (403); the substrate fixing seat (404) is fixedly connected to the base (101); the fiber grating temperature compensation substrate (405) is respectively fixed between the fiber grating spring piece (402) and the substrate pressing plate (403); the fiber grating spring piece (402) and the fiber grating temperature compensation substrate (405) are connected in series in the base (101); The optical fiber (406) of the optical fiber Bragg grating shrapnel monitoring device (4) is led to the optical fiber Bragg grating demodulation and analysis system (5); after the optical fiber Bragg grating demodulation and analysis system (5) demodulates the wavelength of the optical fiber (406), the analyzed data is sent to a remote cloud platform via a wireless communication module, thereby realizing local and remote real-time online monitoring.

2. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor according to claim 1, characterized in that: The connecting rod driving device (2) comprises a driving accessory mounting seat (201), a driving slider (202), a driving guide rod (203), a spring guide column (204) and a spring (205); The drive accessory mounting seat (201) is fixed on the drive slider (202); the drive slider (202) drives the drive accessory mounting seat (201) to flexibly move linearly on the drive guide rod (203); the drive guide rod (203) is fixed on the housing (1); a spring baffle (201-1) is provided on the drive accessory mounting seat (201); a first through hole (201-2) is provided on the spring baffle (201-1); the spring guide column (204) passes through the first through hole (201-2); the spring guide column (204) is fixed on the housing (1); the spring guide column (204) is wound with the spring (205); one end of the spring (205) presses the housing (1) and the other end presses on the drive accessory mounting seat (201), so as to transmit the elastic force to the external connecting rod (3), thereby ensuring that the external connecting rod (3) is always pressed against the monitoring auxiliary tooling (6).

3. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor according to claim 2, characterized in that: The connecting rod driving device (2) comprises a vertical rod guide sleeve (207), a transmission connecting rod (208) and a fixed shaft seat (209); The side surface of the drive accessory mounting seat (201) is connected to a first drive vertical rod (206-1) at an axially vertical position with respect to the drive guide rod (203); one end of the drive guide rod (203) is vertically connected to a second drive vertical rod (206-2); a first vertical rod guide sleeve (207-1) is sleeved on the first drive vertical rod (206-1); a second vertical rod guide sleeve (207-2) is sleeved on the second drive vertical rod (206-2); and a side surface of the second vertical rod guide sleeve (207-2) is connected to a first circular shaft (207-3); The first circular shaft (207-3) is embedded in the driving hole (208-1) of the transmission connecting rod (208); the transmission connecting rod (208) is a long plate-shaped structure; a fixed shaft hole (208-2) is provided in the middle of the transmission connecting rod (208); the fixed shaft seat (209) is fixed on the housing (1); the fixed shaft seat (209) is provided with a fixed shaft (209-1); the fixed shaft (209-1) passes through the fixed shaft hole (208-2); 08-2) is provided, the transmission connecting rod (208) is connected to the base (101), and the transmission connecting rod (208) can be flexibly rotated radially around the fixed axis (209-1); the other end of the transmission connecting rod (208) is provided with a transmission hole (208-3), and the distance from the transmission hole (208-3) to the fixed axis hole (208-2) and the distance from the driving hole (208-1) to the fixed axis hole (208-2) are in a preset ratio.

4. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor according to claim 3, characterized in that: The connecting rod driving device (2) further comprises a driven vertical rod (210), a driven accessory mounting seat (211), a driven slider (212) and a driven guide rod (213); wherein the driven guide rod (213) is fixed to the base (101), the driven slider (212) is movably mounted on the driven guide rod (213), the driven accessory mounting seat (211) is mounted on the driven slider (212), the driven accessory mounting seat 211 is mounted on the driven vertical rod (210), a third vertical rod guide sleeve (207-4) is sleeved on the driven vertical rod (210), and the driven slider (212) drives the driven accessory mounting seat (211) to flexibly move linearly on the driven guide rod (213).

5. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor according to claim 4, characterized in that: The driving guide rod (203), the spring guide column (204), the first driving upright rod (206-1), the second driving upright rod (206-2), the driven upright rod (210) and the driven guide rod (213) are all rod-shaped structures with the same cross-section.

6. The three-dimensional monitoring substrate-type fiber Bragg grating crack sensor according to claim 1, characterized in that: The cross section of the external connecting rod (3) is a square structure, which is used to reduce its elastic deformation, and the universal ball bearing is installed at the end of the universal ball bearing contact rod (304).

7. A dynamic analysis method for a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor, the dynamic analysis method being implemented by a three-dimensional monitoring substrate-type fiber Bragg grating crack sensor as claimed in any one of claims 1 to 6, characterized in that: The dynamic analysis method comprises the following steps: Step S1, fix the three-dimensional monitoring substrate-type fiber Bragg grating crack sensor on a relatively fixed surface, and fix the monitoring auxiliary tooling on the monitored surface; compress the external connecting rods for X, Y, and Z axis monitoring to the middle position of the stroke to ensure that the measurable positive and negative displacement range is maximized; Step S2, the optical fiber (406) of the fiber Bragg grating shrapnel monitoring device (4) is led to the fiber Bragg grating demodulation and analysis system (5), the relative fixed surface and the monitored surface are mapped, and an initial plane data model Ax+By+Cz+D=0 is established with a point on the relative fixed surface as the origin; Step S3, the three-dimensional monitoring substrate fiber Bragg grating crack sensor performs real-time dynamic monitoring of the X, Y, and Z displacements of the monitored surface, demodulates and analyzes the wavelength data, obtains the displacement change (a, b, c), saves the monitoring data, and draws the X, Y, and Z three-dimensional displacement dynamic curves in real time; Step S4, obtaining a normal vector n: (x, y, z) based on the displacement change in the rated time period, and obtaining different-stage plane data models A1x+B1y+C1z+D=0, A2x+B2y+C2z+D=0, ...; Step S5, the fiber Bragg grating demodulation and analysis system (5) sets the over-limit angle and displacement limit threshold, establishes a dynamic model to display the displacement change in real time, and sends the data to the remote cloud platform through the wireless communication module, so as to realize local and remote real-time online monitoring.

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