CN113532303A - Device and method for testing strain position of object by using external strain - Google Patents
Device and method for testing strain position of object by using external strain Download PDFInfo
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Abstract
The invention discloses a device and a method for testing the strain position of an object by using an external strain. The light source driving circuit is connected with the light source, the photoelectric detector and the sensing optical fiber are all connected to the 2X 2 optical coupler, and the sensing optical fiber is tightly wound on the surface of a measured object; the calibration between the position of the wound sensing optical fiber and the detection time is realized through the external stress applying device, and the conversion error which is only dependent on the measurement time, the optical fiber stress position and the object stress position is eliminated; the relation between the one-dimensional coordinates of the optical fibers and the two-dimensional coordinates of the surface of the measured object is established, and the measurement of the strain position of the object is more accurately realized. The invention is used for any complex surface including a variable-diameter object, and solves the problem of the traditional method of directly utilizing the accumulated error of the one-dimensional length of the optical fiber corresponding to the curved surface shape.
Description
Technical Field
The invention relates to a device and a method for testing the strain position of an object, in particular to a device and a method for testing the strain position of the object by using external strain.
Background
The optical time domain reflection technology has the advantages of wide monitoring range, continuous distribution, large response bandwidth, adaptability to severe environment and the like, and long-distance distributed measurement is carried out by utilizing back-scattered signals in optical fibers. The method is applied to ultra-long-distance environment monitoring and monitors the change of the external environment.
In the prior art, the actual position of the object strain is usually determined by the time difference of back scattering, and the distance L in the optical fiber and the detection time t of the back scattering light intensity signal at the point after the self-pulse light is emitted have the following relationship:
L＝t·c/n
where c is the speed of light in vacuum and n is the effective index of refraction of a mode when light is transmitted through the fiber in that mode. In the prior art, light is generally distributed in a straight long distance and is in a linear measurement state, and the generated time error in the above formula is reflected on the distance in a c/n ratio, so that the distance error can be effectively controlled by only controlling the time error.
In the daily practice process, the following disadvantages in the background art are found:
1) when the optical fiber is wound around an object and the on-surface stress measurement is performed, unlike the linear stress measurement in which the linear long distance distribution is performed, the position on the surface is calculated by using time, and the position estimation error of the on-surface position measurement due to the winding characteristics of the optical fiber is generated. Particularly, when the optical fiber is wound on an object with uneven surface, such as a variable-diameter and deformed object, and the surface coordinate of a two-dimensional object is solved by calculating the one-dimensional optical fiber coordinate by using time, the accumulated error caused by the calculation deviation of the length of a single optical fiber ring exists;
2) there is no real-time monitoring and calculation method for the location corresponding to the on-surface stress location calibration.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a method for calibrating and testing the strain position of an object by using an external strain.
The technical scheme adopted by the invention is as follows:
the invention comprises a light source driving circuit, a light source, a 2 multiplied by 2 optical coupler, a photoelectric detector and a sensing optical fiber; the light source driving circuit is connected with the light source, the light output end of the light source is connected with one end of one side of the 2 x 2 optical coupler, the other end of one side of the 2 x 2 optical coupler is connected with the photoelectric detector, one end of the other side of the 2 x 2 optical coupler is connected with one end of the sensing optical fiber, and the sensing optical fiber is tightly wound on the surface of a measured object.
The sensing optical fiber is tightly attached to and uniformly wound on the peripheral surface of the measured object in a spiral winding mode.
The surface of the object to be measured is a convex surface or a plane.
Preferably, the object to be measured is a cylinder-like body, and is generally a cylinder.
In a specific implementation, the object to be measured may be a part or a component of an aircraft, but is not limited thereto.
The light source driving circuit and the photoelectric detector are connected to the circuit detection module, and the circuit detection module is connected with the computer.
The strain applying device is arranged on the side of the measured object along the direction parallel to the length direction of the measured object and is used for applying pressure to the sensing optical fiber on the surface of the measured object.
Because the sensing optical fiber is tightly attached and wound outside the measured object, the strain on the surface of the measured object can be transmitted to the sensing optical fiber, so that light passing through the sensing optical fiber generates different influences and changes, and then the signals detected and received by the photoelectric detector are judged and analyzed to obtain the strain condition and the result on the surface of the measured object.
Secondly, a method for testing the strain position of an object by using applied strain comprises the following steps:
step 1: calibrating the strain position of an object;
step 2: and testing the strain position of the object.
6. The method for testing the strain position of an object by using applied strain as claimed in claim 5, wherein:
the step 1: the object strain position calibration specifically comprises the following steps:
the sensing optical fiber is wound on the outer wall of the surface of the known cylinder object, so that the establishment of a system for calibrating the surface stress position of the object is realized;
then, applying pressure to each position of the surface of the known cylindrical object by using a stress applying device, and accurately determining the spatial position of the surface of the object applying the pressure as a spatial calibration value of the surface of the object;
and measuring the time value of the backscattered light intensity signal generated at each position of the surface of the object and reaching the photoelectric detector as a time calibration value of the surface of the object, thereby establishing the corresponding relation between the spatial position and the measurement time.
The step 1: the object strain position calibration specifically comprises the following steps:
step 1.1: the sensing optical fiber is tightly attached to and uniformly wound on the peripheral surface of a known cylinder object, and the stress applying device applies stress to a plurality of positions of the sensing optical fiber outside the sensing optical fiber, so that the sensing optical fiber is stressed and maintained by the stress applying device at one position at intervals of a section of length;
the positions of the plurality of positions where the sensing optical fiber is stressed in the axial direction of the object are denoted by x1、x2、。。。、 xn、xn+1As a spatial calibration of the object surface;
step 1.2: the light source driving circuit sends a pulse signal to the light source, the driving light source sends a beam of pulse light, the back scattering light intensity signals of all positions of the sensing optical fiber received by the photoelectric detector are recorded in real time, and the recording starting time is set to be zero moment;
step 1.3: when the back scattering light intensity signal recorded in real time is the same as the back scattering light intensity signal detected and received by the photoelectric detector when the light source does not emit pulsed light, stopping recording the signal detected and received by the photoelectric detector, and analyzing and storing the time of each peak value of the back scattering light intensity signal in the time domain;
step 1.4: repeating the step 1.2-1.3, performing multiple tests, and taking a time average value in the multiple tests of each peak value of the signal on the time domain as a time calibration value of the surface of the object;
step 1.5: and corresponding each time calibration value to the respective space calibration value, and establishing the relation between the time calibration value and the space calibration value.
The step 2: and (3) testing the strain position of the object, specifically comprising the following steps:
step 2.1: the sensing optical fiber is tightly attached and uniformly wound on the peripheral surface of the measured object;
step 2.2: the light source driving circuit sends a pulse signal to the light source, the driving light source sends a beam of pulse light, the back scattering light intensity signals of all positions of the sensing optical fiber received by the photoelectric detector are recorded in real time, and the recording starting time is set to be zero moment;
step 2.3: when the back scattering light intensity signal recorded in real time is the same as the back scattering light intensity signal detected and received by the photoelectric detector when the light source does not emit pulsed light, stopping recording the signal detected and received by the photoelectric detector, analyzing whether the back scattering light intensity signal in a time domain has a stress response signal or not, and obtaining the time of the stress response signal;
step 2.4: in the relation between the time calibration value and the space calibration value obtained in the step 1, searching a previous time calibration value and a next time calibration value of the stress response signal time and space calibration values corresponding to the two time calibration values, and calculating an actual space calibration value by using an interpolation method to serve as a position on the sensing optical fiber which actually generates strain;
step 2.5: and then the position of the surface of the measured object which actually generates strain is obtained through conversion according to the geometric corresponding relation between the position on the sensing optical fiber and the surface position of the measured object.
The measured object is a cylinder, the sensing optical fibers are uniformly wound in a spiral winding mode, and the surface position of the measured object which actually generates strain is obtained through the following formula:
xm＝[(tm-tn)xn+(tn+1-tm)xn+1]/(tn+1-tn)
ym＝(tm-tn)lm/(tn+1-tn)
wherein x isnMeans for applying pressure to the sensing optical fiber at the nth position along the axial direction of the known cylindrical object by the strain applying device when the sensing optical fiber is wound around the known cylindrical objectm、tn、tn+1Respectively representing the time of the stress response signal, a time-calibrated value preceding the time of the stress response signal, a time-calibrated value following the time of the stress response signal, xm、ymRespectively representing the object to be measuredThe strain position is the coordinate position along the axial direction and the circumferential direction on the outer circumferential surface of the cylinder, n represents the n-th circle wound by the sensing optical fiber, rmIs the radius of the object to be measured,/mThe circumference of the sensing fiber in the circumferential direction when the sensing fiber is wound around the object to be measured is represented, and the angle mark m represents that the physical quantity is a measured quantity.
The measured object is a cylinder, the sensing optical fiber is uniformly wound in a spiral winding mode, and the number of the sensing optical fiber is 10 (x)n+1-xn)＜2πrnAnd 2.5, processing according to the following formula to obtain the surface position of the measured object which actually generates strain:
xm＝xn
ym＝(tm-tn)yn/(tn+1-tn)
wherein x isnMeans for applying pressure to the sensing optical fiber at the nth position along the axial direction of the known cylindrical object by the strain applying device when the sensing optical fiber is wound around the known cylindrical objectm、tn、tn+1Respectively representing the time of the stress response signal, a time-calibrated value preceding the time of the stress response signal, a time-calibrated value following the time of the stress response signal, xm、ymRespectively representing the coordinate positions of the strained position of the measured object on the outer peripheral surface of the cylinder along the axial direction and the circumferential direction, n represents the n-th circle wound by the sensing optical fiber, m represents the physical quantity as the measured quantity, y representsnShowing the circumference of the nth turn of the fiber optic coil.
The stress response signal is at least 2 times enhanced when the photoelectric detector corresponds to the stress applying point before stress application and after stress application.
The invention realizes the real-time monitoring of the stress on the surface of the measured object by winding the sensing optical fiber on the surface of the measured object. The calibration between the position of the wound sensing optical fiber and the detection time is realized through the external stress applying device, and the conversion error which is only dependent on the measurement time, the optical fiber stress position and the object stress position is eliminated. By establishing the relation between the one-dimensional coordinates of the optical fibers and the two-dimensional coordinates of the surface of the measured object, the strain position of the object is measured more accurately.
The invention has the beneficial effects that:
the invention effectively solves the problem that no position test method corresponding to the on-surface stress position calibration exists in the background technology, thereby realizing the real-time monitoring and calculation of the object surface stress position.
The invention is used for any complex convex surface including a variable-diameter object, and solves the problem of the traditional method of directly utilizing the accumulated error of the one-dimensional length of the optical fiber corresponding to the curved surface shape.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only one embodiment of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1: calibrating and calculating a system diagram of the strain position of the measured object;
FIG. 2: the light intensity of the light source changes with time in a oscillogram;
FIG. 3: outputting a waveform schematic diagram when a calibration strain is applied;
FIG. 4: outputting a waveform schematic diagram when no external strain exists;
FIG. 5: resolving a schematic diagram when a certain point is subjected to an external force;
FIG. 6: and (4) calculating a schematic diagram of the strain position of the object.
FIG. 7: and (4) calculating an actual strain position of the object.
In the figure: the device comprises a light source driving circuit (1), a light source (2), a 2 x 2 optical coupler (3), a photoelectric detector (4), a circuit detection module (5), a computer (6), a sensing optical fiber (7), a strain applying device (8) and a measured object (9).
Detailed Description
The invention is further illustrated by the following figures and examples.
As shown in fig. 1, the apparatus includes a light source driving circuit 1, a light source 2, a 2 × 2 optical coupler 3, a photodetector 4, a sensing fiber 7, and a strain applying device 8; the light source driving circuit 1 is connected with the light source 2, the light output end of the light source 2 is connected with one end of one side of the 2 x 2 optical coupler 3, the other end of one side of the 2 x 2 optical coupler 3 is connected with the photoelectric detector 4, one end of the other side of the 2 x 2 optical coupler 3 is connected with one end of the sensing optical fiber 7, and the other end of the other side of the 2 x 2 optical coupler 3 and the other end of the sensing optical fiber 7 are used as empty ports and are connected with tail optical fibers. The strain applying device 8 is a strip-shaped object which can be made of any material and is attached to a certain circumferential position of the axial direction of the object to be measured 9, and the strain applying device 8 is arranged on the side of the object to be measured 9 along the length direction parallel to the object to be measured 9 and is used for applying pressure to the sensing optical fiber 7 on the surface of the object to be measured 9. The optical time domain reflectometer module is mainly composed of a light source driving circuit 1, a light source 2, a 2 multiplied by 2 optical coupler 3, a photoelectric detector 4 and a circuit detection module 5.
In a specific implementation, as shown in fig. 1, the sensing fiber 7 is tightly and uniformly wound around the outer peripheral surface of the object to be measured 9 in a spiral winding manner. In specific implementation, the sensing optical fiber 7 is wound on the outer wall of the surface of the object to be measured 9 in a single layer, so that the sensing optical fiber 7 completely covers the surface of the position to be measured of the strain of the object to be measured 9.
The LED illumination device further comprises a circuit detection module 5 and a computer 6, wherein the light source driving circuit 1 and the photoelectric detector 4 are connected to the circuit detection module 5, and the circuit detection module 5 is connected with the computer 6.
Because sensing optical fiber 7 hugs closely and twines outside testee 9, the meeting of emergency on testee 9 surface can transmit sensing optical fiber 7 on, leads to the increase of the back scattering light intensity through sensing optical fiber 7, and then judges the analysis with the signal that photoelectric detector 4 detected and received and obtain, the strain condition and the result on testee 9 surface.
Specifically, the light source driving circuit 1 drives the light source 2 to emit light to enter the 2 × 2 optical coupler 3, and the light is transmitted to the sensing optical fiber 7 through the 2 × 2 optical coupler 3, the light generates a backscattered light intensity signal at each position of the sensing optical fiber 7 in the transmission process along the sensing optical fiber 7, and the backscattered light intensity signal returns to the 2 × 2 optical coupler 3, and is transmitted to the photodetector 4 through the 2 × 2 optical coupler 3 to be detected and received.
Each position of the sensing optical fiber 7 where light is transmitted generates a back scattering light intensity signal, the time for generating the back scattering light intensity signal at the position of the sensing optical fiber 7 closer to the 2 x 2 optical coupler 3 is earlier, the shorter the optical path through which the back scattering light intensity signal passes, and the earlier the time for detecting and receiving the back scattering light intensity signal is.
The back scattering light intensity signals generated by the sensing optical fiber 7 are different at the strain position of the object to be measured 9, a larger amplitude value is generated, the photoelectric detector 4 detects and receives signals at different moments, the change of the back scattering light intensity signals is judged, the source and the condition of the back scattering light intensity signals are further determined, and the strain position and the condition of the surface of the object to be measured 9 are further judged.
The embodiment of the invention and the implementation condition are as follows:
step 1: calibrating the strain position of an object;
step 1.1: the sensing optical fiber 7 is tightly and uniformly wound on the peripheral surface of a known cylindrical object in a spiral winding mode, and the stress applying device 8 applies stress to a plurality of positions of the sensing optical fiber 7 outside the sensing optical fiber 7, so that one position of the sensing optical fiber 7 at intervals of a certain length is applied with stress by the stress applying device 8 and is kept;
in the specific implementation, the stress applying device 8 arranged parallel to the axial direction of the object is used for applying pressure to the sensing optical fiber 7 outside the surface of the object in the radial direction, so that the sensing optical fiber 7 is applied with pressure everywhere along the spiral winding of the same axial direction. The positions of the plurality of positions where the sensing fiber 7 is stressed in the axial direction of the object are denoted by x1、x2、。。。、xNAs a spatial calibration of the object surface;
step 1.2: the light source driving circuit 1 sends a pulse signal to the light source 2, the light source 2 is driven to send a beam of pulse light, the back scattering light intensity signal of each position of the sensing optical fiber 7 received by the photoelectric detector 4 is recorded in real time, and the recording starting time is set to be zero moment;
the light source driving circuit 1 is controlled by the circuit detection module 5, so that the light source 2 outputs pulsed light with a light intensity waveform as shown in fig. 2.
The backscattered light intensity signals are collected through the photoelectric detector 4, and data acquisition is carried out by the circuit detection module 5, the waveform diagram of the collected light intensity is shown in figure 3, and the light intensity peak is the same as the number of turns of the sensing optical fiber 7 under the strain applying device 8; the peak values are recorded into the circuit detection module 5 and finally transmitted to the computer 6 for display.
Step 1.3: after the pulse light is propagated and passes through all positions of the sensing fiber 7, the back scattering light intensity signal can not be generated, namely the last back scattering light intensity signal is generated when the pulse light reaches the tail end of the sensing fiber 7. Therefore, when the back scattering light intensity signal recorded in real time is the same as the back scattering light intensity signal detected and received by the photoelectric detector 4 when the light source 2 does not emit pulsed light, namely when the detector data signal is stable as the bottom noise, the recording of the signal detected and received by the photoelectric detector 4 is stopped, and the time of each peak value of the back scattering light intensity signal in the time domain is analyzed and stored;
step 1.4: repeating the step 1.2-1.3, performing multiple tests, taking a time average value in the multiple tests of each peak value of the signal on the time domain as a time calibration value of the surface of the object, and transmitting the time calibration value to a computer; and taking an average value after multiple experiments and recording the average value as calibration data.
Step 1.5: and corresponding each time calibration value to the respective space calibration value, and establishing the relation between the time calibration value and the space calibration value. The number of peaks is the same as the number of locations to which the sensing fiber 7 is stressed, and a time calibration corresponds to a spatial calibration.
In the embodiment, the calibration data is set as follows, the circuit detection module 5 drives the light source 2 at the time 0, and the time when the circuit detection module 5 receives the signal peak is t respectively at the calibration time1，…，tNAnd as a time calibration value of the surface of the object, wherein N is the number of coil turns.
The strain applying means 8 is removed after calibration is completed. After removing the strain applying means 8, the output waveform diagram of the object without external strain is shown schematically in fig. 4.
Therefore, the method effectively solves the problem of accumulated error of calculating the surface stress position of the object by independently utilizing time in the background technology, and further realizes the accurate calibration of the surface stress position of the object.
Step 2: and testing the strain position of the object.
Step 2.1: the sensing optical fiber 7 is tightly attached to the peripheral surface of the measured object 9 in a spiral winding mode and is uniformly wound on the peripheral surface; the construction of the object surface stress position testing system is realized.
Step 2.2: the light source driving circuit 1 sends a pulse signal to the light source 2, the light source 2 is driven to send a beam of pulse light, the back scattering light intensity signal of each position of the sensing optical fiber 7 received by the photoelectric detector 4 is recorded in real time, and the recording starting time is set to be zero moment;
step 2.3: when the back scattering light intensity signal recorded in real time is the same as the back scattering light intensity signal detected and received by the photoelectric detector 4 when the light source 2 does not emit pulsed light, stopping recording the signal detected and received by the photoelectric detector 4, analyzing whether the back scattering light intensity signal in a time domain has a stress response signal, and if so, reading the time of the stress response signal;
the data generated by the measurement of the embodiment is as follows, the circuit detection module 5 is set at the time 0 to drive the light source 2, the graph of the output waveform of the extreme value with the backscattered light intensity signal is shown in fig. 5, it can be seen that the strain change occurs, and the time when the circuit detection module 5 receives the stress response signal is tmWherein t isn≤tm<tn+1， tn、tn+1A previous time calibration value representing the stress response signal time, a subsequent time calibration value representing the stress response signal time, respectively
Step 2.4: in the relation between the time calibration value and the space calibration value obtained in the step 1, searching a previous time calibration value and a next time calibration value of the time recorded by the extremum value and the space calibration values corresponding to the two time calibration values, and calculating an actual space calibration value as a position on the sensing optical fiber 7 which actually generates strain by using an interpolation method;
step 2.5: and then the position of the surface of the measured object 9 which actually generates strain is obtained through conversion according to the geometric corresponding relation between the position on the sensing optical fiber 7 and the surface position of the measured object 9. Real-time calculation and measurement of the object surface stress position testing system are realized.
The measured object 9 is a cylinder, and the sensing optical fiber 7 is uniformly wound in a spiral winding manner, as shown in fig. 6, the surface position of the measured object 9 which is actually strained is obtained by the following formula:
xm＝[(tm-tn)xn+(tn+1-tm)xn+1]/(tn+1-tn)
ym＝(tm-tn)lm/(tn+1-tn)
wherein x isnMeans that the sensing optical fiber 7 is pressed at the nth position along the axial direction of the known cylindrical object by the strain applying device 8 when being wound around the known cylindrical objectm、tn、tn+1Respectively representing the time of the stress response signal, a time-calibrated value preceding the time of the stress response signal, a time-calibrated value following the time of the stress response signal, xm、ymRespectively representing the coordinate positions of the strained position of the measured object 9 along the axial direction and the circumferential direction on the outer circumferential surface of the cylinder, n represents the n-th circle wound by the sensing optical fiber 7, rmIs the maximum radius of the object 9 to be measured,/mThe circumference of the sensing fiber 7 in the circumferential direction when it is wound around the object to be measured 9 is indicated, and the index m indicates that the physical quantity is a measured quantity.
The measured object 9 is a cylinder, and the sensing optical fiber 7 is uniformly wound in a spiral winding mode. For a measured object with an uneven surface, as shown in FIG. 7, for any n satisfying the condition, there is the following relation, xn+1-xn＜＜2πrnIf true, the surface position of the object to be measured 9 that actually undergoes strain is obtained in step 2.5 by processing according to the following formula:
xm＝xn
ym＝(tm-tn)yn/(tn+1-tn)
wherein x isnIndicating that the sensing fiber 7 is wound around a known cylindrical bodyThe strain applying means 8 apply a pressure at the nth position, t, along the axial direction of the body of the known cylinderm、tn、tn+1Respectively representing the time of the stress response signal, a time-calibrated value preceding the time of the stress response signal, a time-calibrated value following the time of the stress response signal, xm、ymRespectively representing the coordinate positions of the strained position of the measured object 9 along the axial direction and the circumferential direction on the outer circumferential surface of the cylinder, n represents the n-th circle wound by the sensing optical fiber 7, rnIs the maximum radius of the object 9 to be measured,/mRepresenting the circumference of the sensing fiber 7 in the circumferential direction when it is wound around the object 9 to be measured, m representing the physical quantity as a measured quantity, ynShowing the circumference of the nth turn of the fiber optic coil.
The invention can be further expanded on the basis of the above-mentioned embodiments, including
1. Calibrating and resolving a single object in the form of a plurality of sensing optical fibers and a plurality of detector groups;
2. the object is calibrated and the position is calculated by adopting a double winding method combining transverse winding and longitudinal winding;
3. the method is a calibration-free mechanical strain position calculation method through temperature measurement under the environment of multi-temperature calibration for realizing acquisition of rapid temperature change while utilizing Brillouin scattering;
4. and the Raman scattering is utilized, and meanwhile, the position calibration and calculation for measuring the temperature change of each point on the distributed surface are carried out.
The above disclosure is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or modifications within the technical scope of the present invention, and shall be covered by the scope of the present invention.
Claims (10)
1. The utility model provides an utilize plus strain to object strain position testing arrangement which characterized in that: the optical fiber sensor comprises a light source driving circuit (1), a light source (2), a 2 multiplied by 2 optical coupler (3), a photoelectric detector (4) and a sensing optical fiber (7); the light source driving circuit (1) is connected with the light source (2), the light output end of the light source (2) is connected with one end of one side of the 2 x 2 optical coupler (3), the other end of one side of the 2 x 2 optical coupler (3) is connected with the photoelectric detector (4), one end of the other side of the 2 x 2 optical coupler (3) is connected with one end of the sensing optical fiber (7), and the sensing optical fiber (7) is tightly wound on the surface of a measured object (9).
2. The apparatus for testing the strain position of an object by applying a strain according to claim 1, wherein: the sensing optical fiber (7) is tightly and uniformly wound on the peripheral surface of the measured object (9) in a spiral winding mode.
3. The apparatus for testing the strain position of an object by applying a strain according to claim 1, wherein: the LED illumination system is characterized by further comprising a circuit detection module (5) and a computer (6), wherein the light source driving circuit (1) and the photoelectric detector (4) are connected to the circuit detection module (5), and the circuit detection module (5) is connected with the computer (6).
4. The apparatus for testing the strain position of an object by applying a strain according to claim 1, wherein: the device also comprises a strain applying device (8), wherein the strain applying device (8) is arranged on the side of the measured object (9) along the direction parallel to the length direction of the measured object (9) and is used for applying pressure to the sensing optical fiber (7) on the surface of the measured object (9).
5. A method for testing the strain position of an object by using an applied strain, which is applied to the device of any one of claims 1 to 4, and is characterized in that: the method comprises the following steps:
step 1: calibrating the strain position of an object;
step 2: and testing the strain position of the object.
6. The method for testing the strain position of an object by using applied strain as claimed in claim 5, wherein: the step 1: the object strain position calibration specifically comprises the following steps:
the sensing optical fiber (7) is wound on the outer wall of the surface of the known cylinder object, so that the establishment of a surface stress position calibration system of the object is realized;
then, applying pressure to each position of the surface of the known cylinder object by using a stress applying device, and determining the spatial position of the surface of the object applying the pressure as a spatial calibration value of the surface of the object;
and measuring the time value of the backscattered light intensity signal generated at each position of the surface of the object and reaching the photoelectric detector (4) as a time calibration value of the surface of the object, thereby establishing the corresponding relation between the spatial position and the measurement time.
7. A method for testing the strain position of an object by using applied strain according to claim 5 or 6, wherein: the step 1: the object strain position calibration specifically comprises the following steps:
step 1.1: the sensing optical fiber (7) is tightly and uniformly wound on the peripheral surface of a known cylinder object, and the stress applying device (8) applies stress to a plurality of positions of the sensing optical fiber (7) outside the sensing optical fiber (7), so that one position of the sensing optical fiber (7) at intervals of a certain length is applied with stress by the stress applying device (8) and is kept;
the positions of the plurality of positions of the sensing optical fiber (7) on which stress is applied along the axial direction of the object are expressed as x1、x2、。。。、xn、xn+1As a spatial calibration of the object surface;
step 1.2: the light source driving circuit (1) sends a pulse signal to the light source (2), the light source (2) is driven to send a beam of pulse light, the real-time recording photoelectric detector (4) receives back scattering light intensity signals at each position of the sensing optical fiber (7), and the recording starting time is set to be zero moment;
step 1.3: when the back scattering light intensity signal recorded in real time is the same as the back scattering light intensity signal detected and received by the photoelectric detector (4) when the light source (2) does not emit pulsed light, stopping recording the signal detected and received by the photoelectric detector (4), and analyzing and storing the time of each peak value of the back scattering light intensity signal in a time domain;
step 1.4: repeating the step 1.2-1.3, performing multiple tests, and taking a time average value in the multiple tests of each peak value of the signal on the time domain as a time calibration value of the surface of the object;
step 1.5: and corresponding each time calibration value to the respective space calibration value, and establishing the relation between the time calibration value and the space calibration value.
8. The method for testing the strain position of an object by using applied strain as claimed in claim 5, wherein: the step 2: and (3) testing the strain position of the object, specifically comprising the following steps:
step 2.1: the sensing optical fiber (7) is tightly attached and uniformly wound on the peripheral surface of a measured object (9);
step 2.2: the light source driving circuit (1) sends a pulse signal to the light source (2), the light source (2) is driven to send a beam of pulse light, the real-time recording photoelectric detector (4) receives back scattering light intensity signals at each position of the sensing optical fiber (7), and the recording starting time is set to be zero moment;
step 2.3: when the back scattering light intensity signal recorded in real time is the same as the back scattering light intensity signal detected and received by the photoelectric detector (4) when the light source (2) does not emit pulsed light, stopping recording the signal detected and received by the photoelectric detector (4), analyzing whether the back scattering light intensity signal in a time domain has a stress response signal or not, and obtaining the time of the stress response signal;
step 2.4: in the relation between the time calibration value and the space calibration value obtained in the step 1, searching a previous time calibration value and a next time calibration value of the stress response signal time and space calibration values corresponding to the two time calibration values, and calculating an actual space calibration value by using an interpolation method to serve as a position on a sensing optical fiber (7) which actually generates strain;
step 2.5: and then the position of the surface of the measured object (9) which actually generates strain is obtained through conversion according to the geometric corresponding relation between the position on the sensing optical fiber (7) and the surface position of the measured object (9).
9. The method for testing the strain position of an object by using applied strain as claimed in claim 8, wherein: the measured object (9) is a cylinder, the sensing optical fiber (7) is uniformly wound in a spiral winding mode, and the surface position of the measured object (9) which actually generates strain is obtained through the following formula:
xm＝[(tm-tn)xn+(tn+1-tm)xn+1]/(tn+1-tn)
ym＝(tm-tn)lm/(tn+1-tn)
wherein x isnMeans for applying a pressure to the sensing fiber (7) at the nth position, t, along the axial direction of the known cylindrical object by the strain applying means (8) when the sensing fiber is wound around the known cylindrical objectm、tn、tn+1Respectively representing the time of the stress response signal, a time-calibrated value preceding the time of the stress response signal, a time-calibrated value following the time of the stress response signal, xm、ymRespectively representing the coordinate positions of the strained position of the measured object (9) on the outer peripheral surface of the cylinder along the axial direction and the circumferential direction, n represents the n-th circle wound by the sensing optical fiber (7), and rmIs the radius of the object (9) to be measured,/mThe circumference of the sensing optical fiber (7) along the circumferential direction when being wound on a measured object (9) is shown, and the angle mark m shows that the physical quantity is a measured quantity.
10. The method for testing the strain position of an object by using applied strain as claimed in claim 8, wherein: the measured object (9) is a cylinder, the sensing optical fiber (7) is uniformly wound in a spiral winding mode, and 10 (x)n+1-xn)＜2πrnAnd 2.5, processing according to the following formula to obtain the surface position of the measured object (9) which is actually strained:
xm＝xn
ym＝(tm-tn)yn/(tn+1-tn)
wherein x isnIndicating that the sensing fiber (7) is applied by the strain applying means (8) when it is wound around the known cylindrical objectThe pressure being at the nth position, t, along the axial direction of the body of the known cylinderm、tn、tn+1Respectively representing the time of the stress response signal, a time-calibrated value preceding the time of the stress response signal, a time-calibrated value following the time of the stress response signal, xm、ymRespectively representing the coordinate positions of the strained position of the measured object (9) on the outer peripheral surface of the cylinder along the axial direction and the circumferential direction, n represents the n-th circle wound by the sensing optical fiber (7), m represents the physical quantity as a measured quantity, y represents the measured quantitynShowing the circumference of the nth turn of the fiber optic coil.
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