Strain performance testing device of distributed strain optical cable and testing method thereof

Abstract

The invention relates to a strain performance testing device of a distributed strain optical cable and a testing method thereof, and belongs to the technical field of optical fiber monitoring technologies. Comprising a test bench, the test bench is provided with a fixed adjusting rack and a movable adjusting rack, the fixed adjusting rack and the movable adjusting rack are respectively provided with a clamp, a to-be-tested optical cable is fixed between the two clamps, and two ends of the to-be-tested optical cable are electrically connected with a tester through a connection jumper wire; the movable adjusting frame moves on the test bed through the movable driving mechanism, so that the movable adjusting frame is close to or far away from the fixed adjusting frame to load or unload the to-be-tested optical cable; a displacement digital display meter is arranged on the movable adjusting frame and is used for displaying the displacement amount of the to-be-measured optical cable on the movable adjusting frame; the fixed adjusting frame is provided with a displacement dial indicator, and the displacement dial indicator is used for displaying the offset of the to-be-measured optical cable on the fixed adjusting frame. The test precision can reach the sensor level, the operation is simple and convenient, and the test efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to a strain performance testing device and a testing method for a distributed strain optical cable, and belongs to the technical field of optical fiber monitoring. Background Art

[0002] In recent years, with the rapid development of my country's national economy, the construction of a series of large-scale engineering projects, represented by the South-to-North Water Diversion Project, has been booming. For these large-scale projects, which impact national economy and people's livelihoods, structural safety has received increasing attention from all sectors of society. From a structural safety perspective, the demand for structural health and safety monitoring in projects such as pipelines, tunnels, and bridges is becoming increasingly prominent. Due to its suitability for continuous monitoring over long lengths, fiber-optic distributed strain monitoring technology has been widely used in structural health monitoring. This technology, based on Brillouin optical time-domain reflectometry, injects short pulses of light and continuous probe light into the ends of an optical fiber. By measuring the frequency changes of the stimulated Brillouin scattered light in the fiber, strain information at each point along the fiber's axis can be obtained. Distributed strain monitoring technology utilizes the Brillouin scattering effect of light in the fiber, allowing monitoring points along the entire length of the fiber to monitor structural strain at corresponding locations. The structural stress is calculated based on relevant information such as the elastic modulus. For long-distance structural safety monitoring, distributed strain monitoring based on fiber-optic sensing technology is more economical and cost-effective for the same density of monitoring points across the cross-section.

[0003] Distributed strain monitoring technology data is divided into three dimensions (time, test distance, and strain value). Compared with traditional point-based two-dimensional data analysis and processing (time and strain value), data processing is more difficult. However, because the data is detailed and has a higher data density, it is conducive to the correlation data analysis of the entire line structure of continuous long-length projects, and can more intuitively reflect the overall structural safety and health status of the project.

[0004] As a special type of strain monitoring sensor, strain cables, a key component in distributed strain monitoring, currently have no relevant national or industry standards. For testing and calibration of their strain performance, the current general practice is to use optical cable tensile testing equipment to conduct quantitative tensile tests. However, since optical cable tensile testing equipment is mainly used to test the maximum tensile force or breaking force of communication optical cables, its loading and unloading forces are large and the speed is fast. In addition, it generally uses a guide wheel winding method to clamp both ends, and the optical cable is fixed by the lateral friction force on the wheel. This makes the entire device too large and there are many interference factors along the line. It is impossible to meet sensor-level testing and analysis requirements, and test results cannot be obtained economically and quickly. In order to more accurately test and calibrate the various strain performance parameters of strain cables, it is urgent to develop a set of scientific and reasonable optical cable strain testing methods to ensure that the results of strain tests in laboratory environments are accurate and reliable. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a strain performance testing device and a testing method for a distributed strain optical cable in response to the above-mentioned prior art. The device is easy to operate, improves testing efficiency, and achieves sensor-level testing accuracy. The cable clamping section is limited to a relatively short distance, so that the stress zones of the optical cable to be tested are clearly defined. The test curve can more accurately reflect the stress state of each part of the optical cable, facilitating subsequent in-depth analysis.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problem is: a strain performance testing device for a distributed strain optical cable, comprising a test bench, wherein a fixed adjustment frame and a movable adjustment frame are provided on the test bench, wherein the fixed adjustment frame and the movable adjustment frame are respectively provided with a clamp, the optical cable to be tested is fixed between the clamps, and the two ends of the optical cable to be tested are electrically connected to the tester via connecting jumpers; the movable adjustment frame is moved on the test bench by a mobile drive mechanism, so that the movable adjustment frame approaches or moves away from the fixed adjustment frame to load or unload the optical cable to be tested; the movable adjustment frame is provided with a displacement digital display, which is used to display the displacement of the optical cable to be tested on the movable adjustment frame; the fixed adjustment frame is provided with a displacement micrometer, which is used to display the offset of the optical cable to be tested on the fixed adjustment frame.

[0007] The mobile drive mechanism includes a horizontally arranged screw rod, which is passed through a movable adjustment frame and is threadedly connected to each other. Pulleys are respectively provided on one end of the screw rod and an output end of the gear reducer. A transmission belt is provided between the two pulleys. The input end of the gear reducer is connected to the motor through a coupling.

[0008] The clamp includes a lower piece and an upper piece of a Huff screw that are relatively combined to form a Huff screw. The center of the Huff screw has a storage cavity. The optical cable to be tested passes through the storage cavity. Two clamps are respectively provided on the optical cable to be tested, and the clamps are respectively arranged at both ends of the storage cavity. Fastening nuts are respectively screwed on both ends of the Huff screw, and the fastening nuts are respectively against the clamps. When the fastening nuts are rotated, the fastening nuts are against the clamps and push the clamps to move toward the storage cavity; two adjusting nuts are also provided on the Huff screw, and the two adjusting nuts are threadedly connected to the Huff screw. When the adjusting nuts are rotated in the same direction, the Huff screw moves, thereby driving the optical cable to be tested to stretch.

[0009] The clip is a cone-shaped structural member, and the clip comprises an upper clip and a lower clip that are relatively combined.

[0010] The fixed adjustment frame is provided with a stretching unit, which includes two stretching blocks arranged at intervals, the two stretching blocks are movably provided on the fixed adjustment frame, and the two stretching blocks are fixedly connected by a horizontally arranged connecting rod; a clamp is provided on one of the stretching blocks; the fixed adjustment frame is provided with a handle, the screw rod of the handle is horizontally rotated on the fixed adjustment frame, and the end of the screw rod is fixedly connected to the other stretching block; the handle is rotated to drive the screw rod to move in the fixed adjustment frame, and the stretching unit is pushed to move horizontally along the fixed adjustment frame, so as to achieve quantitative stretching of the optical cable arranged in the fixed adjustment frame.

[0011] A method for testing the strain performance of a distributed strain optical cable, the method comprising the following steps: Step 1: Before the test, the optical cable to be tested should be placed in an environment with a room temperature of 25±3℃ and a humidity of ≤85% for more than 24 hours; Step 2: Cut a section of the optical cable to be tested and place it on the test bench. The surface of the optical cable to be tested should be smooth and straight. Step 3: After aligning the positions of the fixed adjustment frame and the movable adjustment frame, the optical cable to be tested is fixed to the fixed adjustment frame and the movable adjustment frame respectively using two clamps; the linear distance between the centers of the two clamps is 5000±100mm; Step 4: Mark the surface of the optical cable to be tested close to the edge of the fixture at the exit of the two fixtures to determine whether the optical cable to be tested slips during the test; Step 5: Strip the optical fibers at both ends of the optical cable to be tested, and connect the two optical fibers to the optical fiber input interface of the tester through a jumper. Step 6: Start the strain test software and scan and detect the length and reference strain data of the optical cable to be tested; Step 7: The mobile drive mechanism controls the lead screw to rotate slowly and evenly, so that the mobile adjustment frame moves away from the fixed adjustment frame, so that the optical cable to be tested between the mobile adjustment frame and the fixed adjustment frame is straightened and tightened, and the strain test software is started to scan the strain data of the optical cable to be tested again; Step 8: Determine the test zero position according to the strain test zero position determination method, move the center point of the optical cable to be tested between the two fixtures to the test zero position, and clear the data on the displacement digital display and displacement micrometer; Step 9: Slowly and evenly rotate the handle to stretch the optical cable to the maximum strain limit position according to the tensile test requirements. After standing for a while, observe the changes in the displacement micrometer. After it stabilizes, observe whether the fixture mark slips. Step 10: Slowly and evenly rotate the handle in the opposite direction, loosen the unloading and unload to the test zero position; Step 11: Repeat steps 9 and 10 several times. When the data on the displacement micrometer is stable and the fixture mark does not slip, the optical cable to be tested is officially tested. Step 12: Starting from the test zero position, load or unload step by step according to the set step length. When each step length is reached, use the strain monitoring software to scan and save the strain data, and record the readings of the displacement digital display and displacement micrometer; Step 13: Perform multiple stretching cycles for each standard test, with the interval between each stretching cycle not exceeding 1 hour. The room temperature should be kept constant during the test. Step 14: After the test is completed, save the test data.

[0012] In step 7, if the difference between the midpoint height of the optical cable to be tested and the top surface height of the fixture is less than 5 mm, it is considered to be taut.

[0013] Method for determining the zero position of the strain test in step eight: a. After the two ends of the optical cable to be tested are clamped and fixed, clear the displacement digital display and the micrometer display value to zero, and use the strain gauge to scan the strain data of the optical cable in the relaxed state and the tensioned state respectively: Relaxed state: When the optical cable to be tested is relaxed to the point where the midpoint just touches the table, it is recorded as position A; Tightened state: the clamp does not slip and the optical cable does not slack, which is marked as position B; b: When in position B, the length of the optical cable to be tested between the two end fixtures should be measured and recorded as L, and the stretch value displayed as C. Display = XY, Among them, X is the displacement digital display value, and Y is the displacement micrometer value; c: Import the strain data txt files of position A and position B into an Excel spreadsheet for calculation. Select the 1~2m position of the fixture center as the effective section, and calculate the average strain value of each data point in the effective section, which are recorded as S0 and S1 respectively. d: Substitute the total stretched length L and the average strain values ​​S1 and S0 into the following formula to calculate the actual stretching amount Cactual of the optical cable: Creal=(S1-S0)*10-6*L Among them: S1, S0 units are µɛ, L, C units are mm; e: Calculate C0, C0 = (Cdisplay - Creal) + k, Where k is the correction constant and C0 is the test zero position for the subsequent tensile cycle test.

[0014] The resting time in step nine is more than 10 minutes. If slipping occurs, re-marking is required and the test plan is adjusted to lower the limit until there is no slipping.

[0015] The process of stretching step by step from the test zero position to the maximum limit position in step thirteen is the loading process, and the process from the maximum limit position to the test zero position is the unloading process. A complete loading and unloading process is called a stretching cycle; each time the maximum limit position or the test zero position is reached and reverse loading or unloading is required, the handle should be slightly exceeded before the maximum limit position or the test zero position is rotated in the opposite direction to proceed to the next loading or unloading process.

[0016] In step 13, the distance from the test zero position to the maximum limit position should be evenly divided into 6 to 8 steps.

[0017] Compared with the existing technology, the advantages of the present invention include: a strain performance testing device and testing method for distributed strain optical cables; this testing device is modified from a sensor calibration platform, achieving sensor-level test accuracy, simple operation, and significantly improved testing efficiency. The clamping section of the optical cable to be tested is limited to a relatively short distance, which clearly defines the stress distribution of the optical cable to be tested. The test curve can more accurately reflect the stress state of each part of the optical cable, facilitating subsequent in-depth analysis. By precisely determining the test zero position and the ultimate tensile position, the test process is limited to the linear variation range of the optical cable strain curve, allowing for more accurate acquisition of valid data. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a strain performance testing device for a distributed strain optical cable according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical cable strain / length test curve; Figure 3 for Figure 1 Exploded diagram of the middle fixture; Figure 4 for Figure 1 Schematic diagram of the assembly of the middle fixture; In the figure, 1 test bench, 2 fixed adjustment frame, 3 mobile adjustment frame, 4 fixture, 5 optical cable to be tested, 6 tester, 7 pulley, 8 screw, 9 displacement digital display, 10 displacement micrometer, 11 transmission belt, 12 gear reducer, 13 coupling, 14 motor, 15 left fixture influence section, 16 right fixture influence section, 17 middle effective section, 18 fastening nut, 19 upper clamp, 20 lower clamp, 21 adjusting nut, 22 Haver screw upper piece, 23 Haver screw lower piece, 24 upper bushing, 25 lower bushing, 26 connecting jumper, 27 handle, 28 stretching block, 29 connecting rod. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0020] like Figure 1As shown, a strain performance testing device for a distributed strain optical cable in this embodiment includes a test bench 1. The test bench 1 is provided with a fixed adjustment frame 2 and a movable adjustment frame 3. The fixed adjustment frame 2 is fixed to the test bench 1 by positioning bolts. The movable adjustment frame 3 is driven by a mobile drive mechanism to move along the test bench 1 so that the movable adjustment frame 2 moves closer to or away from the fixed adjustment frame 2. A clamp 4 is provided on the fixed adjustment frame 2 and the movable adjustment frame 3, respectively, and an optical cable 5 to be tested is fixed in the clamp 4. Both ends of the optical cable to be tested are electrically connected to a tester 6 via connecting jumpers 26. A displacement digital display 9 is provided on the movable adjustment frame 3. The displacement digital display 10 is used to display the displacement of the optical cable to be tested, which is located on the movable adjustment frame. A displacement micrometer 10 is provided on the fixed adjustment frame 2. The displacement micrometer 10 is used to display the offset of the optical cable to be tested, which is located on the fixed adjustment frame 2. Due to the pulling force of the movable adjustment frame 3, the clamp 4 on the fixed adjustment frame 2 has a slight directional offset. To ensure the accuracy of the test, the actual displacement of the optical cable to be tested should be based on the difference between the displacement digital display 9 and the displacement micrometer 10. The fixed adjustment frame 2 is provided with a stretching unit, which includes two spaced apart stretching blocks 28. The two stretching blocks 28 are arranged on the fixed adjustment frame 2 and are fixedly connected by a horizontally arranged connecting rod 29. A clamp is set on a stretching block 28; the fixed adjustment frame is provided with a handle 27, the screw of the handle 27 is horizontally rotated on the fixed adjustment frame 2, and the screw is fixedly connected to the other stretching block. Turning the handle drives the screw to move in the fixed adjustment frame, pushing the stretching unit to move horizontally along the fixed adjustment frame to achieve quantitative stretching of the optical cable arranged in the fixed adjustment frame.

[0021] The aforementioned mobile drive mechanism includes a horizontally arranged screw 8, which passes through the mobile adjustment frame 3 and is threadedly connected to the screw 8. Pulleys 7 are respectively provided at one end of the screw 8 and at the output end of a gear reducer 12. A drive belt 11 is interposed between the two pulleys 7. The input end of the gear reducer 12 is connected to a motor 14 via a coupling 13. The motor 14 drives the gear reducer 12, which in turn rotates the pulley 7 and the drive belt 11, causing the screw 8 to rotate, thereby driving the mobile adjustment frame 3 to move, thereby loading and unloading the optical cable 5 to be tested on the mobile adjustment frame 3.

[0022] like Figure 3 、 4As shown, the clamp 4 includes two upper and lower half screw plates 23 and a lower half screw plate 22 that are aligned with each other to form a half screw. The center of the half screw has a storage cavity, and the optical cable to be tested passes through the storage cavity. Two clamps are respectively mounted on the optical cable 5 to be tested, and the clamps are respectively arranged at both ends of the storage cavity. A fastening nut 18 is screwed on each end of the half screw, and the fastening nut 18 abuts against the clamps. When the fastening nut 18 is rotated, the fastening nut 18 abuts against the clamps and pushes the clamps toward the storage cavity, thereby fixing the optical cable 5 to be tested in the half screw. Two adjusting nuts 21 are also provided on the half screw. The two adjusting nuts 21 are threadedly connected to the half screw. When the two adjusting nuts 21 are rotated in the same direction, the half screw moves, thereby driving the optical cable to be tested to move synchronously, that is, the optical cable to be tested is stretched. The half screw is fixed to the fixed adjustment frame 2 or the movable adjustment frame 3 through a bushing.

[0023] The clip is a cone-shaped structural member, and includes an upper clip 19 and a lower clip 20 that are relatively close together. The bushing includes an upper bushing 24 and a lower bushing 25 that are relatively close together.

[0024] The optical cable under test is fixed by the movable adjustment frame 3 and the fixed adjustment frame 2. The actual displacement is accurately measured based on the displacement digital display and displacement micrometer readings. The clamp clamps the optical cable under test and applies longitudinal friction to achieve maximum tensile force transmission. This test method refers to the sensor test calibration method. Based on this, the test method fully considers the differences in structural rigidity between strain gauge cables and point sensors. The linearity and repeatability issues are fully considered in the development of the test method. Methods for determining the test zero position and the limit position are proposed to ensure the accuracy of the test data.

[0025] The method for determining the zero position of strain measurement includes the following operations: a. After the two ends of the optical cable to be tested are clamped and fixed, clear the displacement digital display and the micrometer display value to zero, and use the strain gauge to scan the strain data of the optical cable in the relaxed state and the tensioned state respectively: Relaxed state (when the optical cable to be tested is relaxed to the point where the midpoint just touches the table, this is recorded as position A); Tightened state (no slipping at the clamp and no slack in the cable, marked as position B); b: When in position B, the length of the optical cable to be tested between the two end clamps should be measured and recorded as L, and the stretch value displayed as C 显 (The displacement digital display value is X, the displacement micrometer value is Y, C 显 =XY).

[0026] c: Import the strain data txt files scanned at positions A and B into an Excel spreadsheet for calculation. Select the 1~2m position of the fixture center as the effective segment (according to the graph, try not to select the stress-bearing segment data near the fixture). Calculate the average strain value of each data point in the effective segment (respectively calculated as S0 and S1).

[0027] d: Substitute the total length L and the average strain values ​​S1 and S0 into the following formula to calculate the actual stretching amount C of the optical cable 实 : C 实 = (S1-S0)*10 -6 *L Among them: S1, S0 units are µɛ, L, C units are mm; e: Calculate C0, C 0= (C 显 - C 实 )+k, Wherein, k is the correction constant, which is taken as 1.5 mm according to the empirical value of multiple tests, and C0 is the test zero position of the subsequent tensile cycle test.

[0028] A method for testing the strain performance of a distributed strain optical cable comprises the following steps: Step 1: Before the test, the optical cable to be tested should be placed in an environment with a room temperature of 25±3℃ and a humidity of ≤85% for more than 24 hours.

[0029] Step 2: Cut a 20m length of the optical cable to be tested and place it on the test bench. The surface of the optical cable to be tested should be smooth and straight, and there should be no defects such as damage, cracks, uneven thickness, and distortion on the surface.

[0030] Step 3: After aligning the positions of the fixed and movable adjustment frames, the optical cable to be tested is secured to the fixed and movable adjustment frames using two clamps, respectively. The linear distance between the midpoints of the two clamps is 5000±100mm. Because the lateral clamping force of the clamps has a certain effect on the strain of the optical cable to be tested, experience indicates that the affected area extends approximately 1.5m from the clamp. Based on the spatial positioning accuracy requirements of the equipment, the minimum unaffected section length should be 2m. Due to the length limitation of the test bench, the length of the optical cable to be tested is preferably set at 5m. This allows the 1.5m data at each end of the optical cable to be discarded when calculating the data, and only the valid data in the middle section is used, ensuring the accuracy of the test data.

[0031] Step 4: Mark the surface of the cable under test at the exit of the two clamps and close to the edge of the clamps with self-adhesive paper to determine whether the cable under test is slipping during the test. If a gap is found between the self-adhesive paper and the edge of the clamp during the test, it indicates that the cable has slipped.

[0032] Step 5: Strip appropriate lengths of optical fiber from both ends of the optical cable to be tested, and connect the two optical fibers to the optical fiber input interface of the tester through connecting jumpers.

[0033] Step 6: Start the strain test software and scan and detect the length and reference strain data of the optical cable to be tested.

[0034] Step 7: Set the motor speed and direction. The motor drives the gear reducer, causing the pulley and drive belt to rotate. This in turn causes the lead screw to rotate slowly and evenly, with a rotation speed of less than 10 seconds per revolution. This moves the movable adjustment frame away from the fixed adjustment frame, straightening and tightening the optical cable between the two fixtures. Start the strain gauge software and scan the strain gauge data of the optical cable again. Using the test bench as a reference, the cable is considered taut if the difference between its midpoint height and the fixture top surface is less than 5mm.

[0035] Step 8: Determine the test zero position according to the strain test zero position determination method, move the center point of the optical cable to be tested between the two fixtures to the test zero position, and clear the data on the displacement digital display and displacement micrometer.

[0036] Step 9: Slowly and evenly rotate the handle to stretch the optical cable to its maximum strain limit according to the tensile test requirements. Let it rest for at least 10 minutes, observing the displacement dial indicator. Once it stabilizes, observe the fixture markings for slippage. If slippage occurs, remark the fixture and adjust the test plan to lower the limit until slippage is eliminated. The maximum strain limit is determined based on the structural properties of the optical cable; it varies from cable to cable.

[0037] Step 10: Slowly and evenly rotate the handle in the reverse direction to release and unload to the test zero position.

[0038] Step 11: Repeat steps 9 and 10 for more than 3 times. When the data on the displacement micrometer is basically stable and does not change, and the fixture mark does not slip, the formal test of the optical cable can be started.

[0039] Step 12: Starting from the test zero position, load or unload step by step according to the set step length. When each step length is reached, use the strain monitoring software in the tester to scan and save the strain data, and record the readings of the displacement digital display and displacement micrometer.

[0040] The process of gradually stretching from the test zero position to the maximum limit position is called the loading process. The distance from the test zero position to the maximum limit position should be divided into 6 to 8 steps. The process from the maximum limit position to the test zero position is called the unloading process. A complete loading and unloading process is called a stretching cycle.

[0041] Step 13: Each standard test should be performed for at least 3 stretching cycles. Each stretching cycle test should be performed as continuously as possible, with the interval between each stretching cycle not exceeding 1 hour. The room temperature should be kept constant during the test.

[0042] Step 14: After the test is completed, save the test data. Figure 2As shown, the test data can be subsequently exported to the data analysis and processing software. In order to eliminate the influence of the fixture pressure on the strain test results, the sections affected by the fixture at both ends of the optical cable to be tested should be excluded: the left fixture influence section 15 and the right fixture influence section 16. The left fixture influence section and the right fixture influence section are not less than 1.5m away from the corresponding side fixture. Only the data of the middle effective section 17 between the left fixture influence section 15 and the right fixture influence section 16 are selected for corresponding analysis and calculation. The calculation formula refers to the sensor standard provisions, see Table 2.

[0043] In the above step 12, each time the maximum limit position or the test zero position is reached and reverse loading or unloading is required, the handle should be slightly exceeded before rotating in the opposite direction to proceed to the next loading or unloading process.

[0044] A test plan is developed based on the structural performance of the optical cable to be tested, determining key requirements such as the maximum test displacement, the number of loading and unloading cycles, and the displacement per loading and unloading step. The relevant tests are then conducted accordingly. When the displacement reaches each step position, a Brillouin strain temperature analyzer (BOFDA) is used to perform full-line scanning tests, and the relevant data is recorded and saved.

[0045] After the test, various strain performance indicators were calculated and analyzed based on the relevant data and the calculation formulas specified in the sensor standard (see Table 2). The calculation formulas were implemented in accordance with the "DL / T 1736-2017 Basic Technical Requirements for Fiber Bragg Grating Instruments" (hereinafter referred to as "Standard 1") and the "JJF 1305-2011 Calibration Specifications for Linear Displacement Sensors" (hereinafter referred to as "Standard 2").

[0046] Table 2

[0047] The test device in this application is a modified version of a sensor calibration platform. Its test accuracy reaches sensor-level accuracy, and it is easy to operate, significantly improving test efficiency. The clamping section of the optical cable to be tested is limited to a relatively short distance, which clearly defines the stress zones of the optical cable to be tested. The test curve can more accurately reflect the stress state of each part of the optical cable, facilitating subsequent in-depth analysis. By precisely determining the test zero position and the ultimate tensile position, the test process is limited to the linear variation range of the optical cable strain curve, allowing for more accurate acquisition of valid data.

[0048] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A strain performance testing device for a distributed strain optical cable, characterized by: The test bench comprises a test bench, wherein a fixed adjustment frame and a movable adjustment frame are provided on the test bench, and clamps are provided on the fixed adjustment frame and the movable adjustment frame respectively. The optical cable to be tested is fixed between the clamps, and both ends of the optical cable to be tested are electrically connected to the tester through connecting jumpers; the movable adjustment frame is moved on the test bench by a mobile driving mechanism, so that the movable adjustment frame approaches or moves away from the fixed adjustment frame to load or unload the optical cable to be tested; the movable adjustment frame is provided with a displacement digital display, which is used to display the displacement of the optical cable to be tested on the movable adjustment frame; the fixed adjustment frame is provided with a displacement micrometer, which is used to display the offset of the optical cable to be tested on the fixed adjustment frame.

2. The strain performance testing device for a distributed strain optical cable according to claim 1, characterized in that: The fixed adjustment frame is provided with a stretching unit, and the clamp is fixed to the stretching unit; a handle is rotatably provided on the fixed adjustment frame, and the handle screw is fixedly connected to the stretching unit. Rotating the handle drives the stretching unit to move along the fixed adjustment frame to perform quantitative stretching on the optical cable to be tested.

3. The strain performance testing device for a distributed strain optical cable according to claim 1, characterized in that: The mobile drive mechanism includes a horizontally arranged screw rod, which is passed through a movable adjustment frame and is threadedly connected to each other. Pulleys are respectively provided on one end of the screw rod and an output end of the gear reducer. A transmission belt is provided between the two pulleys. The input end of the gear reducer is connected to the motor through a coupling.

4. The strain performance testing device for a distributed strain optical cable according to claim 1, characterized in that: The clamp includes a lower piece and an upper piece of a Huff screw that are relatively combined to form a Huff screw. The center of the Huff screw has a storage cavity. The optical cable to be tested passes through the storage cavity. Two clamps are respectively provided on the optical cable to be tested, and the clamps are respectively arranged at both ends of the storage cavity. Fastening nuts are respectively screwed on both ends of the Huff screw, and the fastening nuts are respectively against the clamps. When the fastening nuts are rotated, the fastening nuts are against the clamps and push the clamps to move toward the storage cavity; two adjusting nuts are also provided on the Huff screw, and the two adjusting nuts are threadedly connected to the Huff screw. When the adjusting nuts are rotated in the same direction, the Huff screw moves, thereby driving the optical cable to be tested to stretch.

5. The strain performance testing device for a distributed strain optical cable according to claim 4, characterized in that: The clip is a cone-shaped structural member, and the clip comprises an upper clip and a lower clip that are relatively combined.

6. The strain performance testing device for a distributed strain optical cable according to claim 1, characterized in that: The fixed adjustment frame is provided with a stretching unit, which includes two stretching blocks arranged at intervals, the two stretching blocks are movably provided on the fixed adjustment frame, and the two stretching blocks are fixedly connected by a horizontally arranged connecting rod; a clamp is provided on one of the stretching blocks; the fixed adjustment frame is provided with a handle, the screw rod of the handle is horizontally rotated on the fixed adjustment frame, and the end of the screw rod is fixedly connected to the other stretching block; the handle is rotated to drive the screw rod to move in the fixed adjustment frame, and the stretching unit is pushed to move horizontally along the fixed adjustment frame, so as to achieve quantitative stretching of the optical cable arranged in the fixed adjustment frame.

7. A method for testing strain performance of a distributed strain optical cable according to any one of claims 1 to 6, characterized in that: The testing method comprises the following steps: Step 1: Before the test, the optical cable to be tested should be placed in an environment with a room temperature of 25±3℃ and a humidity of ≤85% for more than 24 hours; Step 2: Cut a section of the optical cable to be tested and place it on the test bench. The surface of the optical cable to be tested should be smooth and straight. Step 3: After aligning the positions of the fixed adjustment frame and the movable adjustment frame, the optical cable to be tested is fixed to the fixed adjustment frame and the movable adjustment frame respectively using two clamps; the linear distance between the centers of the two clamps is 5000±100mm; Step 4: Mark the surface of the optical cable to be tested close to the edge of the fixture at the exit of the two fixtures to determine whether the optical cable to be tested slips during the test; Step 5: Strip the optical fibers at both ends of the optical cable to be tested, and connect the two optical fibers to the optical fiber input interface of the tester through a jumper. Step 6: Start the strain test software and scan and detect the length and reference strain data of the optical cable to be tested; Step 7: The mobile drive mechanism controls the lead screw to rotate slowly and evenly, so that the mobile adjustment frame moves away from the fixed adjustment frame, so that the optical cable to be tested between the mobile adjustment frame and the fixed adjustment frame is straightened and tightened, and the strain test software is started to scan the strain data of the optical cable to be tested again; Step 8: Determine the test zero position according to the strain test zero position determination method, move the center point of the optical cable to be tested between the two fixtures to the test zero position, and clear the data on the displacement digital display and displacement micrometer; Step 9: Slowly and evenly rotate the handle to stretch the optical cable to the maximum strain limit position according to the tensile test requirements. After standing for a while, observe the changes in the displacement micrometer. After it stabilizes, observe whether the fixture mark slips. Step 10: Slowly and evenly rotate the handle in the opposite direction, loosen the unloading and unload to the test zero position; Step 11: Repeat steps 9 and 10 several times. When the data on the displacement micrometer is stable and the fixture mark does not slip, the optical cable to be tested is officially tested. Step 12: Starting from the test zero position, load or unload step by step according to the set step length. When each step length is reached, use the strain monitoring software to scan and save the strain data, and record the readings of the displacement digital display and displacement micrometer; Step 13: Perform multiple stretching cycles for each standard test, with the interval between each stretching cycle not exceeding 1 hour. The room temperature should be kept constant during the test. Step 14: After the test is completed, save the test data.

8. The method for testing the strain performance of a distributed strain optical cable according to claim 7, wherein: In step 7, if the difference between the midpoint height of the optical cable to be tested and the top surface height of the fixture is less than 5 mm, it is considered to be taut.

9. The method for testing the strain performance of a distributed strain optical cable according to claim 7, wherein: Method for determining the zero position of the strain test in step eight: a. After the two ends of the optical cable to be tested are clamped and fixed, clear the displacement digital display and the micrometer display value to zero, and use the strain gauge to scan the strain data of the optical cable in the relaxed state and the tensioned state respectively: Relaxed state: When the optical cable to be tested is relaxed to the point where the midpoint just touches the table, it is recorded as position A; Tightened state: the clamp does not slip and the optical cable does not slack, which is marked as position B; b: When in position B, the length of the optical cable to be tested between the two end clamps should be measured and recorded as L, and the stretch value displayed as C 显 =XY, Among them, X is the displacement digital display value, and Y is the displacement micrometer value; c: Import the strain data txt files of position A and position B into an Excel spreadsheet for calculation. Select the 1~2m position of the fixture center as the effective section, and calculate the average strain value of each data point in the effective section, which are recorded as S0 and S1 respectively. d: Substitute the total length L and the average strain values ​​S1 and S0 into the following formula to calculate the actual stretching amount C of the optical cable 实 : C 实 =(S1-S0)*10 -6 *L Among them: S1, S0 units are µɛ, L, C units are mm; e: Calculate C0, C 0= (C 显 - C 实 )+k, Where k is the correction constant and C0 is the test zero position for the subsequent tensile cycle test.

10. The method for testing the strain performance of a distributed strain optical cable according to claim 7, wherein: The resting time in step nine is more than 10 minutes. If slipping occurs, re-marking is required and the test plan is adjusted to lower the limit until there is no slipping.

11. The method for testing the strain performance of a distributed strain optical cable according to claim 7, wherein: The process of stretching step by step from the test zero position to the maximum limit position in step thirteen is the loading process, and the process from the maximum limit position to the test zero position is the unloading process. A complete loading and unloading process is called a stretching cycle; each time the maximum limit position or the test zero position is reached and reverse loading or unloading is required, the handle should be slightly exceeded before the maximum limit position or the test zero position is rotated in the opposite direction to proceed to the next loading or unloading process.

12. The method for testing the strain performance of a distributed strain optical cable according to claim 11, wherein: In step 13, the distance from the test zero position to the maximum limit position should be evenly divided into 6 to 8 steps.

Images