阅读说明：本技术 光纤力传感装置及监测螺栓或螺母松动的系统、方法 (Optical fiber force sensing device and system and method for monitoring bolt or nut loosening ) 是由 张建平 黄春华 于 2020-11-11 设计创作，主要内容包括：本发明公开了一种光纤力传感装置及监测螺栓或螺母松动的系统、方法,该光纤力传感装置包括光纤和两个光纤连接部；光纤上固定有两个光纤连接部,位于两个光纤连接部之间的光纤的长度被设置成大于两个光纤连接部之间的直线距离；两个光纤连接器之间的光纤上设有形变感应段,形变感应段在光纤连接部受到外部作用力时产生形变；该系统包括上述的光纤力传感装置。本发明的光纤力传感装置可用于监控风力发电机的固定螺栓或螺母的松动情况,螺栓或螺母松动时会将光纤拉伸,当光纤拉伸后通过其形变感应段的光信号的变化可以判断该螺栓或螺母已松动或螺栓发生断裂,需要进行维修,提高了风力发电机巡检维护的科学性与可靠性,降低了维护成本。(The invention discloses an optical fiber force sensing device and a system and a method for monitoring bolt or nut looseness, wherein the optical fiber force sensing device comprises an optical fiber and two optical fiber connecting parts; two optical fiber connecting parts are fixed on the optical fiber, and the length of the optical fiber between the two optical fiber connecting parts is set to be larger than the linear distance between the two optical fiber connecting parts; the optical fiber between the two optical fiber connectors is provided with a deformation induction section, and the deformation induction section generates deformation when the optical fiber connecting part is subjected to external acting force; the system comprises the optical fiber force sensing device. The optical fiber force sensing device can be used for monitoring the loosening condition of a fixed bolt or a nut of the wind driven generator, the optical fiber can be stretched when the bolt or the nut is loosened, and the bolt or the nut can be judged to be loosened or the bolt is broken through the change of an optical signal of the deformation induction section after the optical fiber is stretched, so that the maintenance is needed, the scientificity and the reliability of the inspection maintenance of the wind driven generator are improved, and the maintenance cost is reduced.)

1. The optical fiber force sensing device is characterized by comprising an optical fiber and two optical fiber connecting parts;

two optical fiber connecting parts are fixed on the optical fiber, and the length of the optical fiber between the two optical fiber connecting parts is set to be larger than the linear distance between the two optical fiber connecting parts;

and a deformation induction section is arranged on the optical fiber between the two optical fiber connectors, and the deformation induction section is deformed when the optical fiber connecting part receives external acting force.

2. The fiber optic force transducer of claim 1, wherein the strain sensitive section is provided with a fiber grating.

3. The fiber optic force sensing device of claim 1, wherein the deformation sensing segment is configured as a curved segment.

4. The fiber optic force sensing device of claim 3, wherein the strain sensitive segment is configured in a helical configuration, an arcuate configuration, or a wave configuration.

5. The optical fiber force sensing device according to any one of claims 1 to 4, wherein a protective sheath is provided outside the optical fiber between the two optical fiber connection portions, and a cavity is provided in a middle portion of the protective sheath for accommodating the optical fiber between the two optical fiber connection portions.

6. The fiber optic force sensing device of claim 5, wherein the protective sleeve is potted with glue and/or is made of an elastomeric material.

7. A monitoring system for monitoring bolt or nut loosening, comprising an optical fibre force sensing device according to any one of claims 1 to 6;

one optical fiber connecting part of the optical fiber force sensing device is fixed on a bolt or a nut, and the other optical fiber connecting part of the optical fiber force sensing device is fixed on a mounting part of the bolt or the nut;

one end of the optical fiber force sensing device is connected to a signal monitoring device, and the signal monitoring device is used for receiving and analyzing an optical signal returned from the optical fiber force sensing device and qualitatively and/or quantitatively judging the loosening condition of the bolt or the nut according to an analysis result.

8. A monitoring system for monitoring the loosening of a bolt or nut as claimed in claim 7, wherein said optical fiber in said fiber optic force sensing device tends to be in a taut state or a relaxed state when said bolt or nut is rotated in a loosening direction.

9. The monitoring system for monitoring loosening of the bolt or the nut as claimed in claim 7, wherein an alarm unit is provided on the signal monitoring device, and the alarm unit gives an alarm when the signal monitoring device cannot receive the corresponding optical signal after the optical fiber is broken; or the alarm unit gives an alarm when the change of the optical signal received by the signal monitoring device exceeds a threshold value.

10. A method of monitoring with a monitoring system for monitoring loosening of bolts or nuts according to any of claims 7-9, characterized in that the method comprises the steps of:

s1, inputting laser into the optical fiber force sensing device and returning an optical signal, wherein the signal monitoring device monitors and receives the optical signal returned by the optical fiber force sensing device and determines the number of the optical fiber force sensing device according to the wavelength of the optical signal, and the signal monitoring device is preset with the corresponding relation between the wavelength of the returned optical signal and the number of the optical fiber force sensing device;

and S2, analyzing the optical signal returned by the optical fiber force sensing device by the signal monitoring device, and qualitatively and/or quantitatively judging the loosening condition of the bolt or the nut corresponding to the optical fiber force sensing device according to the analyzed result, wherein the signal monitoring device is preset with the corresponding relation between the serial number of the optical fiber force sensing device and the bolt or the nut.

Technical Field

The invention relates to an optical fiber force sensing device and a system and a method for monitoring bolt or nut looseness.

Background

At present, the wind power generation industry is widely popularized all over the world, and due to the fact that most of the wind power generation industry is arranged on the sea or in remote mountainous areas along the sea, daily maintenance is extremely inconvenient. Moreover, the number of bolts for fixing the large-scale wind driven generator is extremely large (more than 500 bolts are fixed on one large-scale wind driven generator), and the bolts or nuts on the wind driven generator are easy to loosen due to the extremely bad environment, so that the wind driven generator is damaged or even collapsed due to the loosening of the bolts or nuts. During the normal operation of the wind generating set, the polling period of the high-strength bolt is generally half a year to one year, the polling period interval is long, and the condition that the bolt or the nut is loosened or the bolt is broken cannot be found in time. Moreover, a large amount of time, manpower and material resources are consumed for each inspection, and particularly for offshore wind power generation units, the units are inconvenient to inspect and have higher inspection cost due to the fact that the units are deep into a coastline for several kilometers.

In the prior art, chinese patent publication No. CN110220682A discloses a monitoring device and a monitoring method for monitoring bolt loosening, which use a narrow bandwidth pulse laser as a light source, and connect a plurality of gratings in series on an optical fiber by time division multiplexing technology to realize the loosening detection of a plurality of bolts. In such a monitoring method, if the optical fiber is disconnected due to the use environment or the like, the monitoring device needs to be entirely replaced, which undoubtedly increases the labor cost and material cost.

Disclosure of Invention

The invention provides an optical fiber force sensing device, a system and a method for monitoring bolt or nut looseness, and aims to overcome the defect that whether a plurality of optical gratings are connected in series by using one optical fiber to detect bolt looseness or not and the defect that the whole bolt needs to be replaced due to the fact that the optical fiber is disconnected in the monitoring device in the prior art.

The invention solves the technical problems through the following technical scheme:

an optical fiber force sensing device comprises an optical fiber and two optical fiber connecting parts;

two optical fiber connecting parts are fixed on the optical fiber, and the length of the optical fiber between the two optical fiber connecting parts is set to be larger than the linear distance between the two optical fiber connecting parts;

and a deformation induction section is arranged on the optical fiber between the two optical fiber connectors, and the deformation induction section is deformed when the optical fiber connecting part receives external acting force.

In this scheme, through fixed and reserve length as the deformation induction section and carry out qualitative and quantitative through two fiber connection portion on optic fibre between two fiber connection portion, optic fibre is stretched or the compression back, and the deformation induction section produces corresponding deformation after receiving certain effort, and the light signal that can make inside pass through changes, can obtain corresponding power signal.

Preferably, the deformation sensing section is provided with a fiber grating.

In the scheme, the fiber grating is used as the deformation induction section of the optical fiber, because the fiber grating has the characteristics of small volume, good wavelength selectivity, no influence of nonlinear effect, insensitive polarization, large bandwidth range, small additional loss, miniaturized device, good coupling, capability of being integrated with other optical fiber devices and the like, and the fiber grating has mature manufacturing process, is easy to be connected with an optical fiber system, is convenient to use and maintain and has low cost, so the fiber grating has good practicability.

Preferably, the deformation sensing section is provided as a bent section.

In this scheme, the deformation response section is set to the bending section, reserves the surplus when making optic fibre stretched, avoids the small change of optic fibre to produce the deformation signal, influences the result of use.

Preferably, the deformation sensing section is configured in a spiral structure, an arc structure or a wave structure.

Preferably, a protective sleeve is arranged outside the optical fiber between the two optical fiber connecting parts, a cavity is arranged in the middle of the protective sleeve, and the cavity is used for accommodating the optical fiber between the two optical fiber connecting parts.

In this scheme, set up the protective sheath and can protect the optic fibre deformation response section between two optic fibre connecting portion, avoid external environment to exert an influence to deformation response section, cause optic fibre force sensing device's output signal result inaccurate.

Preferably, glue is filled in the protective sleeve.

In this scheme, optic fibre in the protective sheath is by tensile back, because irritate glue in the protective sheath, even optic fibre is not straightened, also can make the deformation response section on the optic fibre produce corresponding deformation, can make the light signal that inside passes through change, can obtain corresponding power signal.

Preferably, the protective sleeve is made of an elastic material.

A monitoring system for monitoring bolt or nut loosening comprising an optical fibre force sensing device as described above;

one optical fiber connecting part of the optical fiber force sensing device is fixed on a bolt or a nut, and the other optical fiber connecting part of the optical fiber force sensing device is fixed on a mounting part of the bolt or the nut;

one end of the optical fiber force sensing device is connected to a signal monitoring device, and the signal monitoring device is used for receiving an optical signal returned from the optical fiber force sensing device and qualitatively and/or quantitatively judging the loosening condition of the bolt or the nut according to an analytic result.

In this scheme, be used for this optic fibre force sensing device in monitoring bolt or the not hard up monitoring system of nut, can be used to the not hard up condition of monitoring aerogenerator's fixing bolt or nut, can stretch or compress optic fibre when bolt or nut are not hard up, light through its deformation induction section after optic fibre is stretched or compressed can change after returning light signal, can judge that this bolt or nut has become flexible or the bolt breaks, need maintain, the scientificity and the reliability of maintaining are patrolled and examined to the aerogenerator has been improved, the maintenance cost is reduced.

Preferably, the optical fiber in the optical fiber force sensing device tends to be in a tensioned state or a relaxed state when the bolt or nut is rotated in a loosening direction.

In this scheme, in order to make the deformation sensing section on the optical fiber in the optical fiber force sensing device be stretched or compressed to generate a deformation signal, the optical fiber force sensing device is required to be installed, so that the optical fiber tends to be in a tensioned state or a relaxed state when the bolt or the nut rotates along the loosening direction.

Preferably, an alarm unit is arranged on the signal monitoring device, and the alarm unit gives an alarm when the signal monitoring device cannot receive the corresponding optical signal after the optical fiber is broken; or the alarm unit gives an alarm when the change of the optical signal received by the signal monitoring device exceeds a threshold value.

In this scheme, set up alarm unit for remind the control personnel, the not hard up of bolt or nut has reached alert state, needs carry out quick timely maintenance, avoids causing the loss.

A method of monitoring using the above monitoring system for monitoring bolt or nut loosening, the method comprising the steps of:

s1, inputting laser into the optical fiber force sensing device and returning an optical signal, wherein the signal monitoring device monitors and receives the optical signal returned by the optical fiber force sensing device and determines the number of the optical fiber force sensing device according to the wavelength of the optical signal, and the signal monitoring device is preset with the corresponding relation between the wavelength of the returned optical signal and the number of the optical fiber force sensing device;

and S2, analyzing the optical signal returned by the optical fiber force sensing device by the signal monitoring device, and qualitatively and/or quantitatively judging the loosening condition of the bolt or the nut corresponding to the optical fiber force sensing device according to the analyzed result, wherein the signal monitoring device is preset with the corresponding relation between the serial number of the optical fiber force sensing device and the bolt or the nut.

In the scheme, in the process of monitoring by using the monitoring system, as a plurality of bolts or nuts to be monitored are provided, and the optical fiber force sensing device is arranged at the corresponding position of each bolt or nut, a plurality of optical fiber force sensing devices are arranged, in order to conveniently and rapidly know which bolt or nut is loosened, each optical fiber force sensing device and the corresponding bolt or nut are correspondingly numbered, laser is input into the optical fiber force sensing device, the bolt or nut is loosened to deform the optical fiber in the optical fiber force sensing device, the optical fiber grating on the optical fiber can enable the central wavelength of light with specific wavelength identified by the optical fiber force sensing device to be deviated when the light returns, the change of the central wavelength deviation of optical signals with different wavelengths displayed on the signal monitoring device is observed, namely, which optical fiber in the optical fiber force sensing device is deformed can be rapidly obtained by adopting the wavelength division multiplexing technology, further, the bolt or the nut is loosened, so that the quick maintenance is facilitated.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The positive progress effects of the invention are as follows: the optical fiber force sensing device can be used for monitoring the loosening condition of a fixed bolt or a nut of the wind driven generator, the optical fiber can be stretched when the bolt or the nut is loosened, and the bolt or the nut can be judged to be loosened or the bolt is broken through the change of an optical signal of the deformation induction section after the optical fiber is stretched, so that the maintenance is needed, the scientificity and the reliability of the inspection maintenance of the wind driven generator are improved, and the maintenance cost is reduced.

Drawings

FIG. 1 is a schematic structural diagram of an optical fiber force sensing device according to a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram of the internal structure of the optical fiber force sensing device according to the preferred embodiment of the present invention.

Description of reference numerals:

optical fiber 1

Deformation sensing section 101

Optical fiber connecting part 2

Protective sleeve 3

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

As shown in fig. 1-2, an optical fiber force sensing device of the present invention includes an optical fiber 1 and two optical fiber connecting parts 2; two optical fiber connection parts 2 are fixed on the optical fiber 1, and the length of the optical fiber 1 between the two optical fiber connection parts 2 is set to be larger than the linear distance between the two optical fiber connection parts 2; be equipped with deformation induction section 101 on the optic fibre 1 between two fiber connection portion 2, deformation induction section 101 produces deformation when fiber connection portion 2 receives external force.

Through fixed and reserve length as deformation response section 101 and carry out qualitative and/or ration between two fiber connection portion 2 through two fiber connection portion 2 on optic fibre 1, after optic fibre 1 is stretched, deformation response section 101 produces corresponding deformation after receiving certain pulling force, the light signal that can make inside pass through changes, can obtain corresponding pulling force signal, after optic fibre 1 is compressed, deformation response section 101 produces corresponding deformation after receiving certain pressure, the light signal that can make inside pass through changes, can obtain corresponding pressure signal.

In this embodiment, the deformation sensing section 101 is provided with a fiber grating. The fiber grating is used as the deformation sensing section 101 of the optical fiber 1, because the fiber grating has the characteristics of small volume, good wavelength selectivity, no influence of nonlinear effect, insensitive polarization, large bandwidth range, small additional loss, miniaturized device, good coupling, capability of being integrated with other optical fiber devices and the like, and the fiber grating has mature manufacturing process, is easy to be connected with an optical fiber system, is convenient to use and maintain and has low cost, so the fiber grating has good practicability.

In order to reserve a margin when the optical fiber 1 is stretched and avoid that a small change of the optical fiber 1 generates a deformation signal to affect the use effect, the deformation sensing section 101 is configured as a bending section. Wherein, the deformation sensing section 101 may be configured in a spiral structure, an arc structure, or a wave structure.

In this embodiment, a protective sheath 3 is arranged outside the optical fiber 1 between the two optical fiber connecting parts 2, and a cavity is arranged in the middle of the protective sheath 3 and is used for accommodating the optical fiber 1 between the two optical fiber connecting parts 2. Set up protective sheath 3 and can protect the deformation response section 101 of optic fibre 1 between two optic fibre connecting portion 2, avoid external environment to exert an influence to deformation response section 101, cause optic fibre force sensing device's output signal result inaccurate. Wherein the protective sleeve 3 is made of an elastic material. In other embodiments, the protective sheath 3 may be made of plastic, metal, etc. as long as the deformation sensing section 101 of the optical fiber 1 can be protected. In an example of specific implementation, glue is filled into the protective sheath 3, and the glue needs to fill the protective sheath 3, so that the deformation sensing section 101 can also generate corresponding deformation under the condition that the optical fiber 1 is stretched but not straightened, thereby generating a monitoring signal. The glue adopts flexible soft glue, such as silica gel, etc., to ensure that the protective sleeve has certain stretching length together.

The invention discloses a monitoring system for monitoring the loosening of a bolt or a nut, which comprises the optical fiber force sensing device; one optical fiber connecting part 2 of the optical fiber force sensing device is fixed on a bolt or a nut, and the other optical fiber connecting part 2 of the optical fiber force sensing device is fixed on a mounting part of the bolt or the nut; one end of an optical fiber 1 of the optical fiber force sensing device is connected to a signal monitoring device, and the signal monitoring device is used for receiving optical signals returned in the optical fiber force sensing device and qualitatively and/or quantitatively judging the loosening condition of the bolt or the nut according to an analytic result.

The following describes the process of qualitative or quantitative determination by drawing the deformation sensing segment 101 caused by the tensile force generated by the optical fiber force sensing device when the bolt or the nut is loosened: for example, a qualitative judgment is performed based on whether a signal exists in the analysis result, when the analysis result shows that no returned signal exists, the optical fiber force sensing device is pulled off, namely, the bolt is loosened, and a qualitative judgment can be performed based on whether the analysis result shows that the returned optical signal changes, when the analysis result shows that the optical fiber force sensing device is subjected to an external force, namely, the bolt is loosened; for example, the specific loosening angle of the bolt can be known by analyzing the offset of the returned optical signal, and the optical fiber force sensing device can be indicated to be broken when no returned signal is displayed by the analysis result.

The following describes the qualitative or quantitative determination process by compressing the deformation sensing segment 101 caused by the pressure generated by the optical fiber force sensing device when the bolt or the nut is loosened: for example, qualitative judgment is carried out based on whether the analysis result shows that the returned optical signal changes, and when the analysis result shows that the returned optical signal changes, the optical fiber force sensing device is subjected to an external force acting force, namely, the bolt is loosened; for example, quantitative determination is performed based on the analysis result, and the specific loosening angle of the bolt can be known by analyzing the offset of the returned optical signal.

The optical fiber force sensing device is used in a monitoring system for monitoring the looseness of bolts or nuts, and can be used for monitoring the looseness of fixing bolts or nuts of a wind driven generator, preferably, when the optical fiber 1 tension sensing device is required to be installed, the optical fiber 1 tends to a tensioning state when the bolts or the nuts rotate along the loosening direction, so that the optical fiber 1 can be stretched when the bolts or the nuts are loosened, optical signals can change after the optical fiber 1 is stretched and light passing through the deformation sensing section 101 returns, the bolt or the nut can be judged to be loosened or the bolt is broken, maintenance is required, the scientificity and reliability of inspection and maintenance of the wind driven generator are improved, and the maintenance cost is reduced.

In order to enable the deformation sensing section 101 on the optical fiber 1 in the optical fiber force sensing device to be stretched to generate a deformation signal, the optical fiber 1 tension sensing device is required to be installed, so that the optical fiber 1 tends to be in a tensioned state when the bolt or the nut rotates in the loosening direction. When the bolt or the nut is loosened, so that the deformation sensing section 101 in the optical fiber force sensor is compressed to generate a deformation signal, the optical fiber 1 tension sensing device is required to be installed, so that the optical fiber 1 tends to be in a loosened state when the bolt or the nut rotates in the loosening direction.

An alarm unit is arranged on a signal monitoring device of the monitoring system, and the alarm unit gives an alarm when the signal monitoring device cannot receive the corresponding optical signal after the optical fiber 1 is broken; or the alarm unit gives an alarm when the change of the optical signal received by the signal monitoring device exceeds a threshold value. The alarm unit is arranged to remind monitoring personnel that the loosening of the bolt or the nut reaches a warning state, so that the bolt or the nut needs to be maintained quickly and timely, and loss is avoided.

The invention also discloses a method for monitoring by using the monitoring system for monitoring the loosening of the bolt or the nut, which comprises the following steps:

s1, inputting laser into the optical fiber force sensing device and returning an optical signal, monitoring and receiving the optical signal returned by the optical fiber force sensing device by the signal monitoring device, and determining the number of the optical fiber force sensing device according to the wavelength of the optical signal, wherein the corresponding relation between the wavelength of the returned optical signal and the number of the optical fiber force sensing device is preset in the signal monitoring device;

and S2, analyzing the optical signal returned by the optical fiber force sensing device by the signal monitoring device, and qualitatively and/or quantitatively judging the loosening condition of the bolt or the nut corresponding to the optical fiber force sensing device according to the analyzed result, wherein the corresponding relation between the serial number of the optical fiber force sensing device and the bolt or the nut is preset in the signal monitoring device.

In step S2, the judgment may be qualitative or quantitative, and the following process of qualitative or quantitative judgment is specifically described by generating pressure on the optical fiber force sensing device to stretch the deformation sensing segment 101 when the bolt or the nut is loosened: for example, a qualitative judgment is performed based on whether a signal exists in the analysis result, when the analysis result shows that no returned signal exists, the optical fiber force sensing device is pulled off, namely, the bolt is loosened, and a qualitative judgment can be performed based on whether the analysis result shows that the returned optical signal changes, when the analysis result shows that the optical fiber force sensing device is subjected to an external force, namely, the bolt is loosened; for example, the specific loosening angle of the bolt can be known by analyzing the offset of the returned optical signal, and the optical fiber force sensing device can be indicated to be broken when no returned signal is displayed by the analysis result.

The following describes the qualitative or quantitative determination process by compressing the deformation sensing segment 101 caused by the pressure generated by the optical fiber force sensing device when the bolt or the nut is loosened: for example, qualitative judgment is carried out based on whether the analysis result shows that the returned optical signal changes, and when the analysis result shows that the returned optical signal changes, the optical fiber force sensing device is subjected to an external force acting force, namely, the bolt is loosened; for example, quantitative determination is performed based on the analysis result, and the specific loosening angle of the bolt can be known by analyzing the offset of the returned optical signal. In the process of monitoring by using a monitoring system, because a plurality of bolts need to be monitored, usually, a corresponding bolt is provided with an optical fiber force sensing device, and in order to conveniently and quickly know which bolt is loosened, each optical fiber force sensing device and bolt need to be numbered, for example, the bolt numbers are L1, L2 to Ln, and the corresponding optical fiber force sensing devices are T1, T2 to Tn.

When the laser is emitted into the optical fiber force sensing devices, the laser with the wavelength changing along with the time can be simultaneously sent to all the optical fiber force sensing devices, each optical fiber force sensing device can receive the light with the same wavelength at the same time, but because the sensitive wavelength of the optical fiber grating of each optical fiber force sensing device is different, each optical fiber force sensing device only reflects the light with one wavelength, for example, one optical fiber force sensing device is only sensitive to the light with the wavelength of 332nm, and if the light with the wavelength of 343nm is received, the optical fiber force sensing device can not react. It is assumed here that the optical fiber deformation sensor numbered T1 can reflect light with a central wavelength of 332nm, the optical fiber deformation sensor numbered T2 can reflect light with a central wavelength of 352nm, and when the central wavelength of the light received by the signal monitoring device is 332nm, the light reflected by the optical fiber force sensing device numbered T1 can be determined.

In this embodiment, in order to save the equipment cost, a swept-frequency laser is used to simultaneously transmit laser light with a wavelength that changes with time to all the optical fiber force sensing devices.

The bolt is loosened, so that the optical fiber 1 in the corresponding optical fiber force sensing device is deformed, the optical fiber grating on the optical fiber 1 can enable the central wavelength of the optical signal with the wavelength to shift when the optical signal returns, and the bolt can be quickly loosened by observing the change of the central wavelength shift of the optical signal with different wavelengths displayed on the signal monitoring device by adopting a wavelength division multiplexing technology, so that the quick maintenance is facilitated.

Specifically, when a certain optical fiber force sensing device is deformed by a tensile force, the center wavelength of the optical signal reflected by the certain optical fiber force sensing device is shifted, but the shift amount of the center wavelength of the optical signal reflected by each optical fiber force sensing device is limited, and in this embodiment, it is ensured that the center wavelengths of the optical signals reflected by each optical fiber force sensing device are not overlapped when the center wavelength of the optical signal is shifted to the maximum. Therefore, when the center wavelength of the returned optical signal received by the signal monitoring device is deviated, the serial number of the optical fiber force sensing device reflecting the wavelength light can be determined; for example, the central wavelength of light received by the signal monitoring device is 334nm, and the wavelength 334nm is within the maximum shift range of the central wavelength of light reflected by the optical fiber force sensing device with the number of T2, so that the optical fiber force sensing device with the number of T2 is confirmed to be deformed. The maintenance personnel can only check the bolt with the serial number L2 corresponding to the T2 and maintain the bolt without confirming the bolts one by one, so that the maintenance efficiency is greatly improved.

In this embodiment, a laser transmitter and a demodulator are integrated in the signal monitoring device, the laser transmitter is used for transmitting laser, and the demodulator is used for demodulating the optical signal returned from the optical fiber 1 and judging the change of the external quantity acting on the fiber grating according to the change of the reflection spectrum. The signal monitoring device is used for prestoring the corresponding serial numbers of the optical fiber force sensing device and the bolt and the corresponding relation between the serial number of the optical fiber force sensing device and the sensitive wavelength of the optical fiber force sensing device.

While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.