An optical fiber detection clamp and a method and system for self-evaluation of installation quality thereof

Abstract

The present application relates to the technical field of optical fiber sensing, and especially relates to an optical fiber detection clamp and a mounting quality self-evaluation method and system thereof, which comprises a clamp base, a compression assembly, a guide limiting structure, a pre-tightening limiting structure and an elastic transmission layer; the compression assembly forms a stress closed loop with the clamp base, the guide limiting structure limits the position and posture of the optical fiber detector, the pre-tightening limiting structure limits the pre-tightening parameter, and the elastic transmission layer compensates for the micro-unevenness of the contact interface. After mounting, a standardized external excitation is applied and a response signal is synchronously collected, a mounting quality index is extracted, the mounting quality index is compared with a preset threshold or a qualified baseline, a mounting quality level and a correction suggestion are output, and mounting parameters and evaluation results are bound and stored. The present application can improve the consistency of repeated installation of the optical fiber detector, the mechanical coupling stability and the traceability of the mounting quality.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing technology, and in particular to a fiber optic detection fixture and its installation quality self-assessment method and system. Background Technology

[0002] Fiber optic detectors are widely used in structural health monitoring, equipment vibration diagnosis, bridge and rail transit condition assessment, and energy equipment safety inspection. Their measurement accuracy is highly dependent on the mechanical coupling quality between the detector's sensitive section and the structure being measured. The contact stiffness, friction state, and force path of the installation interface jointly determine the fidelity of the structural response transmitted to the detector's sensitive section. If the coupling quality is poor, even if the back-end demodulation system has excellent performance, it will still lead to signal amplitude attenuation, phase drift, frequency band distortion, and reduced repeatability.

[0003] Existing installation methods mainly include adhesive bonding and mechanical clamping. While adhesive bonding has a lower construction threshold, it suffers from drawbacks such as irreversible disassembly and assembly, long curing periods, difficulty in maintaining consistent adhesive layer thickness, and susceptibility to aging and creep after service. Furthermore, disassembly can easily damage the structural surface. Mechanical clamping, while offering the advantage of detachability, currently available solutions primarily focus on the clamping action, lacking guiding and limiting structures for the detector's position and attitude. Pre-tightening force relies on manual experience for control, lacking stroke limits, torque limits, or constant force constraint mechanisms. Moreover, localized stress concentrations, uneven contact pressure distribution, and micro-slippage often exist at the detector-structure interface, leading to poor reassembly consistency. In addition, existing installation processes lack rapid acceptance methods for coupling quality. After installation, it is impossible to determine whether the current installation has achieved the target coupling state through objective indicators. Installation parameters, interface material conditions, and evaluation results are not recorded, resulting in an invisible, untraceable, and unverifiable state of installation quality. Therefore, a fiber optic detection clamp and its installation quality self-assessment method and system are currently needed. Summary of the Invention

[0004] To address the technical problems of irreversible installation methods, poor reassembly consistency, and unquantifiable acceptance of installation quality in existing fiber optic detector installation methods, this invention provides a fiber optic detector fixture and its self-assessment method and system for installation quality.

[0005] In a first aspect, the present invention provides an optical fiber detection fixture, which adopts the following technical solution: A fiber optic detection fixture includes a fixture base, a clamping assembly, a guide and limiting structure, a pre-tightening and limiting structure, and an elastic transfer layer; The fixture base is provided with an installation area for placing the fiber optic detector, and the lower surface of the fixture base is provided with a mating surface that is adapted to the surface of the structure being measured. The clamping assembly is mounted on the fixture base, with the pressure-applying end of the clamping assembly facing the installation area, and forming a closed-loop force distribution with the fixture base through the installation area; The guide limiting structure is disposed on at least one of the clamp base and the clamping assembly, and is located on the side, end or in a position corresponding to the package of the fiber optic detector in the mounting area, so as to limit at least two degrees of freedom of the fiber optic detector in the lateral, axial and attitude directions. The pre-tightening limiting structure is disposed on the locking path between the clamp base and the clamping assembly to limit the pre-tightening displacement, pre-tightening torque or clamping load of the clamping assembly. The elastic transfer layer is disposed at at least one contact interface between the fiber optic detector and the structure under test and between the fiber optic detector and the clamping assembly.

[0006] Furthermore, the guide limiting structure includes at least one of the following: V-shaped guide groove, double-sided retaining edge, anti-rotation shoulder, end face positioning step, and pin hole type auxiliary positioning component; The V-shaped guide groove, double-sided retaining edge, anti-rotation shoulder, end face positioning step, and pin hole auxiliary positioning component are set on the clamp base and / or clamping assembly and located on the periphery of the installation area, for jointly constraining the lateral position, axial position, and attitude angle of the fiber optic detector.

[0007] Furthermore, the clamping assembly includes a pressure plate or a pressure cap, which is connected to the clamp base by fasteners, and the end of the pressure plate or pressure cap facing the installation area forms a pressure end; The pressure end is provided with a swinging pressure head or a floating pressure block. The swinging pressure head swings relative to the pressure plate or pressure cap within a preset angle range. The floating pressure block is used to move along the pressing direction within a limited range and to perform lateral displacement or posture adjustment. The pressure application position of the clamping component is set to correspond to the encapsulation or non-sensitive bearing area of ​​the fiber optic detector.

[0008] Furthermore, the pre-tightening limiting structure includes one or more of the following: a travel limiting element, a torque limiting element, and a constant force limiting element disposed on the locking path between the clamp base and the clamping assembly; The stroke limiting element includes a limiting sleeve, a stepped stop, and a set of position shims, used to limit the maximum compression displacement of the clamping assembly; the torque limiting element includes a torque limiting fastener, a torque wrench, or a fastening assembly with a slippage structure, used to limit the maximum locking torque of the clamping assembly; the constant force limiting element includes a disc spring assembly, a spring plate, a wave washer, and an elastic column, used to apply an elastic load to the clamping assembly within a preset working displacement range. The stroke limiting element, torque limiting element, and constant force limiting element are disposed on the locking path between the clamp base and the clamping assembly.

[0009] Furthermore, the elastic transfer layer is disposed on at least one side of the fiber optic detector. The elastic transfer layer is composed of a thin elastic pad, a high-friction micro-textured sheet, a fiber-reinforced elastic sheet, or a multilayer composite material. The elastic transfer layer is replaceable relative to the clamp base and the clamping assembly. The thickness of the elastic transfer layer is 0.1 mm to 2 mm.

[0010] Secondly, a self-assessment method for the installation quality of an optical fiber detection fixture includes: S1. Obtain the surface information of the neighborhood of the target measurement point of the structure under test, select the contact surface type of the fixture base and configure the elastic transfer layer according to the surface information; S2. Place the fiber optic detector into the fixture base, and constrain the position and attitude of the fiber optic detector through the guide and limiting structure so that the fiber optic detector falls into the preset position window. S3. The pre-tightening limit structure is used to perform parameterized pre-tightening control on the clamping assembly, so that the pre-tightening parameters fall into the preset range, and a stable mechanical coupling compensated by the elastic transfer layer is established between the fiber optic detector and the structure under test or between the clamping assemblies. S4. Apply a standardized external excitation near the fiber optic detector and simultaneously acquire the response signal of the fiber optic detector; S5. Preprocess the response signal, extract the installation quality index, and compare the installation quality index with the preset threshold or qualified baseline. S6. Based on the comparison results, determine the current installation status level, output correction suggestions, and bind and store the installation parameters, interface material status, index results and measurement point information to form an installation quality traceability record.

[0011] Furthermore, the configuration of the elastic transfer layer includes acquiring surface contour data, local curvature, installation reachable space size, and target measurement point position of the neighborhood of the target measurement point of the structure under test; A preset length installation window is selected with the target measurement point as the center. The contour data within the installation window is fitted and calculated to obtain the local radius of curvature and flatness deviation. The installation scenario type is determined by adaptability judgment based on flatness deviation, local radius of curvature and installation space size. The installation scenario type includes planar installation scenario, curved surface installation scenario and irregular or restricted installation scenario. Select the type of mating surface of the clamp base based on the determined installation scenario, and select the clamping components and elastic transfer layer in combination with the fiber optic detector package size, sensitive direction and target monitoring type.

[0012] Furthermore, the establishment of a stable mechanical coupling compensated by the elastic transmission layer includes pre-tightening control of the clamping assembly by at least one of a stroke limiting element, a torque limiting element, and a constant force elastic element. The preload displacement, preload torque, or clamping load is used as the preload parameter, and the preload parameter is controlled within the corresponding preset range. The clamping load satisfies the following within the working displacement range: , An elastic transfer layer is incorporated to compensate for microscopic surface irregularities at the contact interface, thereby obtaining the pressure distribution dispersion within the contact area. and the equivalent friction stability coefficient of the interface ,when and At that time, it is determined that a stable mechanical coupling has been established; in, To clamp the load, The target is clamped with a load. To determine the allowable fluctuation threshold of the clamping load, To preset the uniformity threshold, This is the preset anti-slip threshold.

[0013] Furthermore, the comparison of the installation quality indicators with preset thresholds or qualified baselines includes performing DC removal, detrending, bandpass filtering, outlier removal, time window truncation, and windowing on the response signal to obtain a preprocessed response signal; The peak amplitude, noise floor, signal-to-noise ratio, repetitive excitation correlation coefficient, and frequency response consistency are extracted from the preprocessed response signal and used as installation quality indicators. Multiple parameters of the installation quality indicators are compared with their corresponding preset thresholds, and the degree of matching between the current response spectrum and the qualified baseline spectrum is determined based on the frequency response consistency. The expression for the frequency response consistency is: , in, For frequency response consistency, For the number of frequency points, The current response spectrum is at the 1st Spectral amplitude at each frequency point For the qualified baseline spectrum in the first Spectral amplitude at each frequency point.

[0014] Thirdly, a self-assessment system for the installation quality of an optical fiber detection fixture includes: The module includes a standard incentive module, a data acquisition module, an evaluation and judgment module, and a storage and traceability module. The standard excitation module is used to apply controlled, standardized external excitation at predetermined excitation locations on the structure under test and to record the excitation parameters. The data acquisition module is connected to the fiber optic demodulation equipment or signal acquisition circuit to synchronously acquire the response signal output by the fiber optic detector under standardized external excitation, and to sample, synchronize, buffer and preprocess the response signal. The evaluation and judgment module is connected to the data acquisition module and is used to extract installation quality indicators based on the preprocessed response signal, compare the installation quality indicators with preset thresholds or qualified baselines, and output installation quality level and correction suggestions based on the comparison results. The storage traceability module is connected to the evaluation and judgment module and is used to bind and store installation parameters, interface material status, excitation parameters, installation quality indicators, installation quality level, correction suggestions and measurement point information to form a traceable installation quality record.

[0015] In summary, the present invention has the following beneficial technical effects: 1. This invention forms a closed-loop force distribution through the installation area by using a clamp base and a clamping assembly, and uses a guide and limiting structure to constrain the lateral position, axial position and orientation of the fiber optic detector, thereby achieving positional and orientational consistency of the fiber optic detector during repeated assembly and disassembly, and avoiding the problems of difficult disassembly and reuse of adhesive installation methods.

[0016] 2. This invention uses a pre-tightening limiting structure to parametrically control the pre-tightening displacement, pre-tightening torque, or clamping load of the clamping assembly. In conjunction with an elastic transmission layer to compensate for the microscopic surface unevenness of the contact interface, it achieves uniformity of contact pressure and stabilization of interface friction state. This can suppress interface micro-slippage and local relaxation, and improve the stability of the transmission of strain or vibration information of the measured structure to the fiber optic detector.

[0017] 3. This invention selects the type of bonding surface based on the surface contour, local curvature, and installation space conditions of the neighborhood of the target measurement point of the structure under test, and adapts to different installation scenarios through planar bonding surfaces, curved bonding surfaces, or replaceable bonding pads. This enables stable installation of the fiber optic detection fixture in planar structures, curved structures, and irregular or restricted installation scenarios, thereby improving the fixture's scenario adaptability and reusability.

[0018] 4. This invention achieves rapid quantitative assessment of installation quality through standardized external stimuli, synchronous acquisition of response signals, extraction of installation quality indicators, comparison of thresholds or qualified baselines, and grade determination. At the same time, it binds and stores installation parameters, interface material status, indicator results, correction suggestions, and measurement point information to form a verifiable and traceable installation quality record, reducing the reliance on human experience for installation quality. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an optical fiber detection fixture provided in an embodiment of the present invention; Figure 2 This is a structural diagram of the guide and limiting structure provided in an embodiment of the present invention; Figure 3 This is a diagram of the pre-tightening limiting structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the installation cross-section and force closed loop of the optical fiber detection fixture provided in an embodiment of the present invention; wherein, Figure 4 (a) is a structural diagram under planar structure. Figure 4 (b) is a structural diagram of the curved surface structure.

[0020] Figure 5 These are structural diagrams of the pre-tightening limiting structure provided in embodiments of the present invention under different configurations; wherein, Figure 5 (a) is a structural diagram of the gear limit mode. Figure 5 (b) is a structural diagram under constant force limiting mode.

[0021] Figure 6 This is a schematic diagram of the adaptive swing structure according to an embodiment of the present invention; Figure 7 A flowchart illustrating the self-assessment method for the installation quality of the optical fiber detection fixture provided in this embodiment of the invention; Figure 8 This is a schematic diagram illustrating the implementation effect of an embodiment of the present invention; wherein, Figure 8 (a) is a schematic diagram of standardized external incentives. Figure 8 (b) is the time-domain response diagram. Figure 8 (c) is the frequency domain response diagram.

[0022] 1. Fixture base; 2. Clamping assembly; 3. Guide and limiting structure; 4. Pre-tightening and limiting structure; 5. Elastic transmission layer; 6. Fiber optic detector; 7. Structure under test; 8. Center bolt; 9. Nut; 10. Gear shim assembly; 11. Disc spring assembly; 12. Swinging pressure head; 13. Ball joint connector; 14. Flexible pad layer. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings.

[0024] Example 1 Reference Figure 1 This embodiment provides an optical fiber detection fixture, including a fixture base 1, a clamping assembly 2, a guide limiting structure 3, a pre-tightening limiting structure 4, and an elastic transmission layer 5, for mounting an optical fiber detector 6 onto the surface of the structure 7 to be tested without adhesive and repeatably.

[0025] The fixture base 1 is provided with an installation area for placing the fiber optic detector 6. The lower surface of the fixture base 1 forms a mating surface that is adapted to the surface of the structure 7 being measured. The clamping component 2 is disposed on the fixture base 1. The pressure end of the clamping component 2 is set towards the installation area and forms a force closed loop with the fixture base 1 through the installation area.

[0026] The mating surface of the clamp base 1 can be set as a flat mating surface, a curved mating surface, or a composite mating surface with replaceable mating pads according to the installation requirements. To improve the adaptability of the clamp to different installation scenarios, the clamp base 1 can also be equipped with modular mating pads or quick-replacement mounting base plates. For pipes, beam edges, or irregular support components with different radii of curvature, a variety of mating pad modules with different surface morphologies can be prefabricated and detachably connected to the clamp base 1 through threaded connectors, snap-fit ​​connectors, or magnetic accessories. This ensures that the overall structure of the clamp base 1 is universal while enabling the clamp to adapt to the installation requirements of flat, curved, and irregular surfaces.

[0027] like Figure 1 , Figure 2 As shown, the guide limiting structure 3 is used to limit at least two degrees of freedom of the fiber optic detector 6 in the lateral, axial and attitude directions. The guide limiting structure 3 is disposed on at least one of the clamp base 1 and the clamping assembly 2, and is located on the side, end or corresponding position of the fiber optic detector 6 package in the installation area. The guide limiting structure 3 can be integrally formed with the clamp base 1 or the clamping assembly 2, or it can be installed on the clamp base 1 or the clamping assembly 2 by means of threaded connection, snap-fit, plug-in or detachable fastening, so that the corresponding guide limiting structure 3 can be replaced according to the different package shape and positioning requirements of the fiber optic detector 6.

[0028] The guide and limiting structure 3 includes at least one of the following: a V-shaped guide groove, double-sided retaining edges, an anti-rotation shoulder, an end-face positioning step, and a pin-hole type auxiliary positioning component. When the packaging shape of the fiber optic detector 6 can achieve the required degree of freedom constraint through a single guide and limiting structure, one type of guide and limiting structure is used. When it is necessary to simultaneously limit the lateral position, axial position, and attitude direction of the fiber optic detector 6, a combination of two or more guide and limiting structures is used, specifically: The two side baffles are respectively set on opposite sides of the installation area, and a guide channel is formed between the two baffles for the fiber optic detector 6 to be inserted. After the fiber optic detector 6 is inserted into the guide channel, the two opposite sides of its package contact the corresponding baffles respectively to restrict the fiber optic detector 6 from moving in the lateral direction of the installation area. The two side baffles are suitable for long strip, rectangular or packaged components with relatively parallel sides.

[0029] A V-shaped guide groove is provided within the mounting area of ​​the clamp base 1, and the V-shaped guide groove has two opposing inclined guide surfaces. After the fiber optic detector 6 is placed into the V-shaped guide groove, the outer peripheral surface of its package contacts the two inclined guide surfaces respectively. When the clamping assembly 2 applies a pre-tightening force, the package automatically centers along the two inclined guide surfaces, thereby limiting the radial offset and attitude deflection of the fiber optic detector 6. The V-shaped guide groove is suitable for cylindrical, near-cylindrical, or arc-shaped fiber optic detectors 6.

[0030] An anti-rotation shoulder is mounted on the clamping base 1 or the clamping assembly 2, and is located on the side or circumferential positioning part of the fiber optic detector 6 package. The anti-rotation shoulder has an anti-rotation surface that mates with the positioning plane, boss, or notch on the package. After the fiber optic detector 6 is installed in place, the corresponding positioning part on the package abuts against the anti-rotation surface to restrict the fiber optic detector 6 from rotating around its own axis. The anti-rotation shoulder is suitable for fiber optic detectors 6 with a clear directional requirement for the sensitive direction, and also for scenarios where cylindrical or near-cylindrical packages may rotate circumferentially within a V-shaped guide groove.

[0031] An end-face positioning step is located at the axial end of the installation area, forming an axial positioning surface on the side facing the fiber optic detector 6. After the fiber optic detector 6 moves along the installation area to a preset position, the axial end face of its encapsulation abuts against the axial positioning surface to restrict the fiber optic detector 6 from continuing to move axially or moving in the opposite direction. The end-face positioning step is suitable for scenarios with a clearly defined encapsulation end face, where it is necessary to maintain a fixed axial position of the sensitive segment of the fiber optic detector 6 relative to the target measuring point.

[0032] The pin-hole type auxiliary positioning component includes a cooperating positioning pin and a positioning hole. The positioning pin can be located on the fixture base 1 or the clamping assembly 2, with the positioning hole correspondingly located on the package of the fiber optic detector 6; alternatively, the positioning pin can be located on the package of the fiber optic detector 6, with the positioning hole correspondingly located on the fixture base 1 or the clamping assembly 2. During installation of the fiber optic detector 6, the positioning pin is inserted into the positioning hole, and the lateral offset, axial offset, and rotation of the fiber optic detector 6 are limited by the insertion and engagement of the positioning pin and the positioning hole. The pin-hole type auxiliary positioning component is suitable for scenarios requiring high accuracy in repeated installations, where the package size is small, or where stable and repeatable positioning is difficult to achieve using only edge guards, guide grooves, and positioning steps.

[0033] The sensitive direction of the fiber optic detector 6 has a preset positional relationship with the positioning reference on its package, and the guide limiting structure 3 remains fixed relative to the clamp base 1. Therefore, when the fiber optic detector 6 completes the positioning engagement with the guide limiting structure 3 and is locked by the clamping assembly 2, the sensitive direction of the fiber optic detector 6 can remain within a preset attitude range relative to the clamp base 1 and the measured structure 7. During disassembly and reassembly, the fiber optic detector 6 returns to the preset position and attitude under the constraint of the same guide limiting structure 3, thus falling into the preset position window, and ensuring that its sensitive direction is consistent with or forms a preset angular relationship with the preset monitoring direction of the measured structure 7.

[0034] like Figure 1 , Figure 3 and Figure 4 As shown, the clamping assembly 2 is disposed on the fixture base 1 and is used to apply a stable preload to the fiber optic detector 6 located within the installation area. The clamping assembly 2 includes one or more of the following: a pressure plate, a fastener, a pressure cap, a swinging pressure head, and a floating pressure block. Depending on the packaging shape of the fiber optic detector 6, the installation space, the pressure-bearing area, and the surface morphology of the structure under test 7, the clamping assembly 2 can be a pressure plate or a pressure cap alone, or a swinging pressure head or a floating pressure block can be provided at the pressure-applying end of the pressure plate or pressure cap to form a combined clamping structure.

[0035] When a pressure plate is used for clamping, the pressure plate is positioned above the installation area. At least one end of the pressure plate is connected to the clamp base 1 via fasteners, and the side of the pressure plate facing the installation area forms a pressure surface. When the fasteners are tightened, the pressure plate moves towards the clamp base 1, causing the pressure surface to press against the fiber optic detector 6. The pressure plate is suitable for long, rectangular, or fiber optic detectors 6 with a large pressure-bearing surface, so as to distribute the clamping load over a large contact area. In this embodiment, the clamping assembly 2 includes a pressure plate, a central bolt 8, and a nut 9. The central bolt 8 passes through the pressure plate, and the nut 9 is connected to the central bolt 8. When the nut 9 is tightened, the pressure plate moves along the central bolt 8 towards the clamp base 1 and presses against the fiber optic detector 6. After the nut 9 is released from its locking state, the pressure plate moves away from the installation area to allow the fiber optic detector 6 to be removed or reinstalled.

[0036] When using a pressure cap for clamping, the pressure cap is positioned above the mounting area and engages with the connecting part on the clamp base 1 via a threaded connection. The end of the pressure cap facing the fiber optic detector 6 forms the pressure end. Rotating the pressure cap moves it closer to or further away from the mounting area along its thread axis to apply or release preload to the fiber optic detector 6. The pressure cap is suitable for cylindrical, near-cylindrical, or small-sized fiber optic detectors 6, and is also suitable for scenarios where installation space is limited and it is difficult to arrange horizontal pressure plates.

[0037] like Figure 4As shown, when the pressure-bearing surface of the fiber optic detector 6 is tilted, the structure under test 7 is a curved surface, or there may be angular deviations during installation, a swing pressure head is provided at the pressure end of the pressure plate or pressure cap. The swing pressure head is located between the pressure plate or pressure cap and the fiber optic detector 6, and can swing relative to the pressure plate or pressure cap within a preset angle range, so that its working surface can be adaptively adjusted according to the surface angle of the fiber optic detector 6 package.

[0038] When the pressure center of the pressure plate or pressure cap may deviate from the pressure-bearing area of ​​the fiber optic detector 6, or when there is local unevenness on the upper surface of the fiber optic detector 6 package, a floating pressure block is provided at the pressure end of the pressure plate or pressure cap. The floating pressure block is held on the clamping assembly 2 by a limiting groove, guide hole, or limiting connector, and can move along the clamping direction within a limited range, while generating lateral displacement or attitude adjustment to compensate for the positional deviation between the pressure center and the pressure-bearing area and reduce local off-center load.

[0039] The side of the pressure plate, pressure cap, swing pressure head or floating pressure block that contacts the fiber optic detector 6 can be set as a micro-arc surface, or a flexible pad 14 can be set to increase the actual contact area and reduce local stress concentration. Regardless of which of the above-mentioned clamping structures is used, the pressure application position of the clamping component 2 corresponds to the encapsulation or non-sensitive load-bearing area of ​​the fiber optic detector 6, and does not use the exposed fiber sensitive section as the direct clamping force-bearing part, so as to avoid the clamping load directly damaging the fiber sensitive section, or introducing unexpected local strain into the fiber optic detector 6.

[0040] like Figure 6 As shown, in one specific embodiment, the pressure plate is configured as an adaptive swing structure, including a pressure plate body, a swing head 12, a hinge shaft or ball joint connector 13, and a flexible pad layer 14. The pressure plate body is connected to the fixture base 1 by a central bolt 8, and the pressure plate body and the swing head are connected by a hinge shaft or ball joint connector 13, so that the swing head can swing around the hinge portion within a preset angle range; the working surface of the swing head 12 that contacts the fiber optic detector 6 is configured as a micro-arc surface or is attached with a flexible pad layer 14.

[0041] The technical principle of the adaptive swing structure is as follows: When the clamping component 2 applies a pre-tightening force to the fiber optic detector 6, if there is a slight curvature on the surface of the structure under test 7 or a slight angular deviation occurs during installation, the swinging pressure head 12 automatically swings around the hinge axis or ball joint connector 13 under the action of the pre-tightening force after contacting the package of the fiber optic detector 6, until its working surface is in contact with the surface of the package. The micro-arc surface or flexible pad 14 undergoes elastic deformation under the action of the pre-tightening force, filling the micro-contact gap and making the contact pressure distribution tend to be uniform. Thus, the adaptive swing structure transforms the point contact or line contact caused by the angular deviation into surface contact, reducing local off-center load and stress concentration. At the same time, it enables the pre-tightening force to be stably transmitted to the fiber optic detector 6 and the structure under test 7 along the designed force path, thereby improving the installation repeatability and mechanical coupling stability of the fiber optic detection fixture.

[0042] like Figure 3 , Figure 5 As shown, the pre-tightening limiting structure 4 is disposed on the locking path between the clamp base 1 and the clamping assembly 2, and is used to limit the pre-tightening displacement, pre-tightening torque or clamping load of the clamping assembly 2 within a preset range. Based on the packaging size of the fiber optic detector 6, the compression characteristics of the elastic transmission layer 5, the installation space, and the control requirements of the pre-tightening parameters, the pre-tightening limiting structure 4 adopts one of the following methods: stroke limiting, torque limiting, and constant force limiting, or a combination of two or more of these limiting methods.

[0043] When the travel limiting method is adopted, the pre-tightening limiting structure 4 includes at least one of the following: a limiting sleeve, a stepped stop, a replaceable shim, and a set of position shims. The limiting sleeve is sleeved on the outside of the central bolt 8 and located between the pressure plate and the clamp base 1. After the pressure plate moves to the clamp base 1 to the preset position, both ends of the limiting sleeve abut against the pressure plate and the clamp base 1 respectively to limit the pressure plate from moving further. The stepped stop is provided on at least one of the clamp base 1 and the pressure plate. When the pressure plate moves to the preset position, the corresponding stepped stop surfaces abut against each other to limit the maximum compression displacement of the pressure plate. The replaceable shim or set of position shims 10 is provided between the pressure plate, the clamp base 1, the nut 9, or the limiting sleeve. By changing the number of shims or the total thickness of the shims, the maximum moving distance of the pressure plate is adjusted, thereby forming different pre-tightening displacement positions.

[0044] The travel limit method is suitable for scenarios where the package size of the fiber optic detector 6 and the initial thickness of the elastic transfer layer 5 are relatively stable, and there is a definite correspondence between the clamping load and the compression displacement. During installation, locking the pressure plate to the limit sleeve, step stop, or stop shim group to form a mechanical stop state ensures a consistent compression displacement for each installation.

[0045] When using a torque limiting method, the pre-tightening limiting structure 4 includes a torque-limiting fastener or a fastening assembly with a slippage structure. The torque-limiting fastener is located at the threaded locking position formed by the central bolt 8 and the nut 9, or it can replace the ordinary nut 9. The fastening assembly with a slippage structure includes a cooperating drive part and a locking part; when the applied locking torque does not reach the set value, the drive part drives the locking part to rotate, causing the pressure plate to move towards the clamp base 1; when the locking torque reaches the set value, slippage or free rotation occurs between the drive part and the locking part to limit the locking torque from continuing to increase.

[0046] like Figure 5 As shown, when using the constant force limiting method, the pre-tightening limiting structure 4 includes at least one of the following: disc spring assembly 11, spring plate, wave washer, and elastic column. The aforementioned constant force elastic element is disposed on the locking path formed by the central bolt 8 and nut 9, or between the pressure plate and the clamp base 1. When locking the clamping assembly 2, the constant force elastic element undergoes compressive deformation as the pressure plate moves, and applies a relatively stable elastic load to the pressure plate within a preset working displacement range. The disc spring assembly 11 is sleeved on the outside of the central bolt 8 and located between the nut 9 and the pressure plate, or between the pressure plate and the clamp base 1; the wave washer is sleeved on the outside of the central bolt 8 and disposed between adjacent bearing surfaces; the spring plate or elastic column is disposed in the corresponding mounting groove between the pressure plate and the clamp base 1.

[0047] Stroke limit, torque limit, and constant force limit can also be used in combination. When it is necessary to simultaneously limit the maximum compression displacement and reduce clamping load fluctuation, a combination of stroke limit and constant force limit can be used. The maximum compression displacement is limited by the limit sleeve, stepped stop, or stop shim assembly, and the elastic load is provided by the disc spring assembly 11, spring sheet, wave washer, or elastic column within the compression displacement range. When it is necessary to limit the maximum torque applied during installation and compensate for assembly dimensional deviations, a combination of torque limit and constant force limit can be used.

[0048] In one specific embodiment, the pre-tightening limiting structure 4 includes a set of position shims 10 and a set of disc springs 11. Both the set of position shims 10 and the set of disc springs 11 are sleeved on the outside of the central bolt 8 and are positioned on the locking path formed by the central bolt 8 and the nut 9. By increasing or decreasing the number of shims in the set of position shims 10 or adjusting the total thickness of the shims, the maximum compression displacement of the clamping assembly 2 is limited in stages. The set of disc springs 11 is deformed under pressure during the locking process of the clamping assembly 2 and provides a relatively stable clamping load to the pressure plate within a preset compression stroke range. The set of position shims 10 and the set of disc springs 11 work together to enable the clamping assembly 2 to simultaneously have the functions of limiting compression displacement and stabilizing clamping load.

[0049] The elastic transfer layer 5 is disposed between the fiber optic detector 6 and the structure under test 7 and / or between the fiber optic detector 6 and the clamping assembly 2. Its placement is determined based on the surface condition of the contact interface, the encapsulation structure of the fiber optic detector 6, the pressure application method of the clamping assembly 2, and the frequency range of the target monitoring quantity. The elastic transfer layer 5 is composed of a thin elastic pad, a high-friction micro-textured sheet, a fiber-reinforced elastic sheet, or a multi-layer composite material, with a thickness of 0.1 mm to 2 mm and a hardness of Shore A20 to 80. It is replaceable relative to the clamp base 1 and the clamping assembly 2.

[0050] When the contact surfaces between the fiber optic detector 6 and the measured structure 7 have microscopic irregularities, local curvature, surface roughness differences, or are prone to relative micro-slippage, an elastic transfer layer 5 is disposed between the fiber optic detector 6 and the measured structure 7. After the clamping assembly 2 applies a preload, the elastic transfer layer 5 undergoes compressive deformation at the contact interface, filling the tiny contact gap between the fiber optic detector 6 and the measured structure 7, increasing the effective contact area, homogenizing the interface contact pressure, and improving the interface friction stability, thereby suppressing micro-slippage of the fiber optic detector 6 relative to the measured structure 7. This arrangement is mainly used to improve the mechanical coupling state between the fiber optic detector 6 and the measured structure 7, enabling the strain or vibration response of the measured structure 7 to be stably transmitted to the fiber optic detector 6.

[0051] When a stable fit has been achieved between the fiber optic detector 6 and the structure under test 7, but the pressure surface of the pressure plate, pressure cap, swing pressure head 12, or floating pressure block is a rigid surface, or the pressure-bearing surface of the fiber optic detector 6's encapsulation has local unevenness, a small bearing area, or weak compressive strength, an elastic transfer layer 5 is disposed between the fiber optic detector 6 and the clamping assembly 2. Under the action of pre-tightening force, the elastic transfer layer 5 at this location buffers and disperses the load applied by the clamping assembly 2, allowing the concentrated load to be evenly transferred to the non-sensitive bearing area of ​​the fiber optic detector 6's encapsulation, thereby reducing local off-center loading, stress concentration, and local deformation of the encapsulation, and preventing the clamping assembly 2 from directly contacting or damaging the sensitive section of the optical fiber.

[0052] When improved mechanical coupling is required between the fiber optic detector 6 and the structure under test 7, and pressure equalization protection is also needed between the clamping assembly 2 and the fiber optic detector 6, elastic transfer layers 5 can be provided on both sides of the fiber optic detector 6. The elastic transfer layer 5 between the fiber optic detector 6 and the structure under test 7 compensates for the lower contact interface, improves frictional stability, and suppresses micro-slippage; the elastic transfer layer 5 between the fiber optic detector 6 and the clamping assembly 2 disperses the upper clamping load and protects the encapsulation of the fiber optic detector 6. The elastic transfer layers 5 on both sides can be made of the same material, or different thicknesses, hardnesses, or surface morphologies can be used depending on the different functions of the contact interfaces on both sides.

[0053] The specific location and parameters of the elastic transfer layer 5 are determined based on the surface roughness and local curvature of the structure under test 7, the packaging size and pressure-bearing capacity of the fiber optic detector 6, the pressure application area of ​​the clamping component 2, the preload, and the target monitoring frequency band. For high-frequency vibration monitoring scenarios, to reduce the impact of the added flexibility of the elastic transfer layer 5 on the transmission of high-frequency response, it is preferable to select an elastic transfer layer 5 with a smaller thickness, higher hardness, and a larger coefficient of friction, provided that the interface adhesion and anti-slip requirements are met. For installation scenarios with rough surfaces, curved structures, or large local flatness deviations, it is preferable to select an elastic transfer layer 5 with a larger thickness and higher flexibility to improve the compensation capability for contact gaps and surface morphology. For scenarios where the pressure-bearing capacity of the fiber optic detector 6 packaging is weak or the pressure application area of ​​the clamping component 2 is small, it is preferable to set a highly flexible elastic transfer layer 5 between the fiber optic detector 6 and the clamping component 2 to reduce local stress concentration.

[0054] Example 2 This embodiment provides a method for using an optical fiber detection fixture, including: In use, based on the surface morphology and installation space conditions at the target measurement point of the structure under test 7, select the corresponding flat bonding surface, curved bonding pad, or modular adapter base plate, and attach the bonding surface of the clamp base 1 to the corresponding surface of the structure under test 7. Based on the contact state between the fiber optic detector 6 and the structure under test 7, and between the fiber optic detector 6 and the clamping assembly 2, place the elastic transfer layer 5 at the corresponding contact interface.

[0055] The fiber optic detector 6 is placed into the mounting area of ​​the fixture base 1, and moved to the preset position along the guide limiting structure 3. The lateral position, axial position and attitude direction are constrained by the double-sided baffles, end face positioning steps, V-shaped guide grooves or pin hole auxiliary positioning parts, so that the fiber optic detector 6 falls into the preset position window.

[0056] The pressure plate is moved towards the fixture base 1 by the central bolt 8 and nut 9, so that the pressure end of the pressure plate acts on the encapsulation or non-sensitive load area of ​​the fiber optic detector 6; the clamping assembly 2 is continued to be tightened until the pre-tightening limit structure 4 reaches the preset limit stroke, pre-tightening torque or clamping load. At this time, a force closed loop is formed between the fixture base 1, the clamping assembly 2, the fiber optic detector 6 and the structure under test 7. The elastic transmission layer 5 compensates for the micro-unevenness of the contact interface under the action of the controlled pre-tightening force, so that a stable and repeatable mechanical coupling is established between the fiber optic detector 6 and the structure under test 7.

[0057] During disassembly, release the locking state of the clamping assembly 2 and remove the fiber optic detector 6; during reinstallation, place the fiber optic detector 6 according to the same guiding and limiting method, and use the same pre-tightening parameters to lock the clamping assembly 2, so that the fiber optic detector 6 returns to the preset position, attitude and pre-tightening state, realizing glue-free disassembly and repeated installation of the fiber optic detection fixture.

[0058] Example 3 The difference between this embodiment and Embodiment 1 is that this embodiment provides a self-assessment method for the installation quality of an optical fiber detection fixture, including: The method takes the mechanical installation state established by the clamp base 1, the clamping assembly 2, the guide limiting structure 3, the pre-tightening limiting structure 4 and the elastic transmission layer 5 as the evaluation object. Through surface adaptation, guide positioning, parameterized pre-tightening, standardized excitation, response signal acquisition, installation quality index calculation, grade determination and result traceability, the mechanical coupling quality between the fiber optic detector 6 and the structure under test 7 is quantitatively evaluated.

[0059] like Figure 7 As shown, S1, obtain the surface information of the neighborhood of the target measurement point of the structure under test, select the contact surface type of the fixture base 1 according to the surface information and configure the elastic transfer layer 5.

[0060] First, the surface information of the neighborhood of the target measurement point on the structure under test is acquired. This surface information includes at least surface contour data, local curvature, accessible installation space dimensions, and the location of the target measurement point. Surface contour data can be obtained through one or more methods, such as manual measurement, contour gauge fitting, image acquisition and recognition, or 3D scanning. Preferably, an installation window of a preset length is selected centered on the target measurement point, and the contour data within this window is fitted and calculated to obtain the local radius of curvature. and flatness deviation The flatness deviation can be defined as the maximum absolute value of the normal distance from the fitting reference surface to each sampling point, expressed as: , in, For flatness deviation, For the first The normal distance from each sampling point to the fitting reference surface. To represent the corresponding sampling points on all surfaces The maximum value is selected from the values; the local radius of curvature can be obtained by circular arc fitting or surface fitting, preferably, ,in For local curvature, Let be the local radius of curvature.

[0061] Based on the flatness deviation of the installation window Local radius of curvature and achievable space dimensions Perform adaptation judgment: when and When the installation is determined to be on a flat surface, a flat mating surface is selected; when... Falling into the preset surface adaptation range When the installation is determined to be on a curved surface, a matching curved surface mat should be selected; when and It does not meet the requirements for fitting a single surface, or the achievable spatial size Less than the standard base installation threshold When the installation scenario is determined to be irregular or restricted, a modular adapter base plate is selected. Among these, This is the flatness deviation threshold. For planar installation, a radius of curvature threshold is determined. , These are the lower and upper limits of the surface adaptation range, respectively. To accommodate the available space dimensions for installation, This is the installation space threshold for the standard fixture base.

[0062] The aforementioned thresholds are pre-calibrated based on the specifications of the fixture base 1, the length of the installation window, the thickness and compression compensation capability of the elastic transfer layer 5, the packaging size of the fiber optic detector 6, and the allowable mechanical coupling error. Different specifications of the fixture base 1 and elastic transfer layer 5 correspond to a set of threshold parameters. During calibration, under the same guiding and positioning method and pre-tightening parameters, standard samples with different flatness deviations and radii of curvature are repeatedly installed. The installation quality under different surface conditions is evaluated based on the fixture fit and the response signal under standardized external excitation. The parameter boundaries that still meet the contact stability requirements and the qualified installation quality indicators are determined as the judgment thresholds for the corresponding installation scenarios.

[0063] Specifically, flatness deviation threshold The flatness deviation is determined based on the maximum surface undulation that the elastic transfer layer 5 can compensate for under a preset pre-tightened state. During calibration, the flatness deviation of the standard specimens is increased step by step, and fixture installation and standardized external excitation tests are performed separately. When the contact state or installation quality index fails to meet the qualification conditions for the first time, the maximum flatness deviation that still meets the qualification conditions at the previous level is determined as the flatness deviation threshold. .

[0064] Planar installation determines the radius of curvature threshold The length of the installation window is determined based on the length of the mounting window and the maximum allowable arc sagitta of the flat mating surface. Let the length of the mounting window along the curvature direction be... The local radius of curvature of the surface is The maximum sagitta of the curved surface relative to the chord surface within the mounting window is Its expression is: , when This indicates that the elastic transfer layer 5 can compensate for the shape deviation between the curved surface and the flat mating surface under a preset pre-tightened state, and the surface can be treated as a flat installation scenario. The radius of curvature corresponding to the time is determined as the radius of curvature threshold for planar installation. .

[0065] Surface adaptation range The curvature radius of the curved surface bonding pad is determined based on its design radius of curvature, allowable deformation range, and the compensation capability of the elastic transfer layer 5. During calibration, standard curved surface specimens with different radii of curvature are selected, and the curved surface bonding pad is installed on each specimen. Tests are conducted under the same preload parameters and standardized external excitation conditions. The minimum and maximum radii of curvature corresponding to when both the bonding state and installation quality indicators meet the preset requirements are determined as follows: and .

[0066] Installation space threshold The installation space threshold is determined based on the outer envelope dimensions of the standard fixture base 1, the insertion space of the fiber optic detector 6, the locking stroke of the clamping assembly 2, and the operating margin required for the installation tools. During calibration, the minimum space required to complete the placement of the fixture base 1, insertion of the fiber optic detector 6, locking of the clamping assembly 2, and disassembly operations is measured, and this minimum space size is determined as the installation space threshold. .when If the standard fixture base 1 is unable to complete the normal installation operation, the scenario is identified as an irregular or restricted installation scenario.

[0067] After determining the installation scenario type, and considering the package size, sensitive direction, and target monitoring type of the fiber optic detector 6, select the corresponding clamping base 1, clamping assembly 2, and elastic transmission layer 5. For high-frequency vibration monitoring scenarios, select an elastic transmission layer 5 with a smaller thickness and higher coefficient of friction; for rough surfaces or curved structures, select an elastic transmission layer 5 with a larger thickness and higher flexibility. After configuration, clean the contact surface of the structure under test 7 to eliminate the influence of oil, particles, and local protrusions on the contact state.

[0068] S2. Guiding Positioning and Repeated Installation. The operator places the fiber optic detector into the fixture base and uses one or more combinations of V-shaped guide grooves, double-sided baffles, end-face positioning steps, anti-rotation shoulders, or pin-hole auxiliary positioning components to constrain the lateral position, axial position, and angular attitude of the fiber optic detector, ensuring it falls into the preset position window.

[0069] Preferably, the lateral offset can be defined separately. Axial offset and attitude deviation angle and with , , This serves as a criterion for successful repositioning. The key to this step is not simply pressing down the detector, but rather using repositioning technology to ensure that the force path and sensitive direction of the detector relative to the measured structure remain within a preset error range after each disassembly and reassembly, thereby reducing response dispersion caused by reassembly deviations.

[0070] in, This is the lateral offset. This is the axial offset. The attitude deviation angle is... This is the horizontal offset threshold. This is the axial offset threshold. The attitude deviation angle threshold is defined as follows. The lateral position, axial position, and attitude angle of the fiber optic detector 6 when it is in standard positioning state are used as positioning references, and are denoted as follows: , and The lateral position, axial position, and attitude angle of the fiber optic detector 6 in its current installation state are denoted as follows: , and Then the lateral offset, axial offset, and attitude deviation angle satisfy the following: , , , when , and At that time, it is determined that the position and orientation of the fiber optic detector 6 meet the repeatability requirements.

[0071] The standard positioning state can be predetermined based on the design dimensions of the clamp base 1, the guide limiting structure 3, and the fiber optic detector 6, or it can be the initial installation state that has been judged as qualified by the self-assessment of installation quality as the positioning reference. For the same model of fiber optic detector 6, the same specification of clamp base 1, and the same guide limiting structure 3, the same positioning reference and threshold parameters are used.

[0072] Horizontal offset threshold The axial offset threshold is determined based on the lateral fit clearance between the double-sided flanges, V-shaped guide grooves, or pin-hole type auxiliary positioning components and the fiber optic detector 6 package, the manufacturing and assembly errors of related components, and the allowable lateral position deviation of the sensitive section of the fiber optic detector 6. The attitude deviation angle threshold is determined based on the fit clearance between the end-face positioning step and the axial end face of the fiber optic detector 6 package, the allowable axial position deviation of the sensitive segment of the fiber optic detector 6 relative to the target measuring point, and the manufacturing and assembly errors of the end-face positioning structure. The determination is based on the allowable rotational clearance of the anti-rotation shoulder, pin-hole auxiliary positioning component or V-shaped guide groove, the allowable angle between the sensitive direction of the fiber optic detector 6 and the preset monitoring direction, and the manufacturing and assembly errors of the relevant positioning structure.

[0073] In a preferred threshold calibration method, the permissible lateral geometric deviation is first determined based on the design dimensions of the guide limiting structure 3 and the actual fit clearance. Axial geometric tolerance and attitude geometry tolerance Then, under the same preload parameters and standardized external excitation conditions, progressively increasing lateral offset, axial offset, and attitude deflection were applied to the fiber optic detector 6, and the response signals under each deviation state were collected. When at least one of the peak amplitude, signal-to-noise ratio, repetitive excitation correlation coefficient, or frequency response consistency fails to meet the corresponding qualification condition for the first time, the maximum deviation in the previous deviation level that still meets the installation quality requirements is determined as the permissible lateral response deviation. Axial response allowable deviation and attitude response allowable deviation .

[0074] Horizontal offset threshold Take the allowable deviation of the lateral geometry With respect to allowable deviation of lateral response The smaller value in the range; axial offset threshold Take the axial geometric tolerance With axial response allowable deviation The smaller value in the range; attitude deviation angle threshold Take attitude geometry tolerance With attitude response allowable deviation The smaller values ​​in the range are expressed as follows: , , , Therefore, the set threshold does not exceed the geometric positioning range that the guide limiting structure 3 itself can guarantee, nor does it exceed the deviation range allowed for the fiber optic detector 6 to maintain qualified response characteristics. Threshold calibration is performed for different fiber optic detector models, fixture specifications, sensitive section lengths, and target monitoring types, and the corresponding lateral offset threshold, axial offset threshold, and attitude deviation angle threshold are used as repeatability judgment parameters for that model and installation scenario.

[0075] S3. Establishment of preload control and stability coupling. After the guiding and positioning are completed, the clamping process is parametrically controlled by the limit sleeve, stop shim group, step stop, torque limiting fastener, disc spring group, wave washer or other constant force elastic element, so that the preload displacement, preload torque or clamping load falls into the repeatable set range.

[0076] Preferably, when a travel limit method is used, the preload displacement... Defined as reference height before clamping Stable height after compression The difference is expressed as: , in, For pre-tightening displacement, when When the position is within the preset displacement range, it is determined that the clamping component 2 has reached the set clamping displacement.

[0077] When torque control is used, the preload torque is denoted as: Clamping load Estimates can be made based on empirical relationships: , in The torque coefficient, The nominal diameter of the fastener. For preload torque, when When the load is within the preset load range, it is determined that the clamping component 2 has reached the preset pre-tightening state.

[0078] When a constant force element is used, the clamping load fluctuation within the working displacement range satisfies: , in The target is clamped with a load. To allow for fluctuation thresholds, an elastic transmission layer is used between the detector and the measured structure and / or between the detector and the clamping assembly to compensate for local contact pressure unevenness, thereby improving frictional stability and suppressing micro-slippage. Preferably, the pressure distribution dispersion within the contact area is... As an indicator of contact uniformity, the pressure distribution dispersion Standard deviation of contact pressure within the contact area With average contact pressure The ratio, its expression is: , when When the contact pressure distribution is deemed to meet the homogenization requirement, then... The preset uniformity threshold is used.

[0079] Preset uniformity threshold Calibration was performed based on the permissible local pressure range of the fiber optic detector 6 package, the pressure equalization compensation capability of the elastic transmission layer 5, and the influence of contact pressure distribution on the stability of the detection response. During calibration, under the same fixture specifications, elastic transmission layer 5, and preload parameters, installation samples with different pressure distribution dispersions were formed by changing the surface flatness of the tested structure 7 and the installation posture or preload state of the fiber optic detector 6. The pressure distribution and response signal under standardized external excitation were recorded for each installation sample.

[0080] Based on the maximum permissible local contact pressure of the fiber optic detector's 6-package and the effective pressure-bearing ratio of the contact area, the upper limit of the permissible geometric contact uniformity is determined. The upper limit of the allowable pressure distribution dispersion is determined based on the peak amplitude, signal-to-noise ratio, repetitive excitation correlation coefficient, and frequency response uniformity while still meeting the corresponding qualification conditions. Preset uniformity threshold Pick and The smaller value in the range is expressed as: , Therefore, a preset uniformity threshold is needed. It does not exceed the unevenness of contact pressure that the fiber optic detector's 6-package can withstand, nor does it exceed the allowable range of pressure distribution dispersion to maintain a stable response signal.

[0081] Simultaneously obtain the interface equivalent friction stability coefficient. The equivalent frictional stability coefficient of the interface. This is used to represent the ability of the fiber optic detector 6 and the structure under test 7 to resist tangential relative slippage. In one calibration method, tangential loads are applied stepwise to the fiber optic detector 6 after pre-tightening installation, and the critical tangential load at which identifiable relative slippage begins to occur at the interface is denoted as... The corresponding normal clamping load is denoted as Interface equivalent friction stability coefficient The expression is: , when At that time, it is determined that the contact interface has the ability to suppress micro-slippage, among which, This is the preset anti-slip threshold.

[0082] Preset anti-slip threshold The maximum tangential disturbance force, minimum normal clamping load, and preset safety factor that the structure under test 7 may withstand in the installed state are determined. The maximum tangential disturbance force that the structure under test 7 may transmit to the installation interface of the fiber optic detector 6 under target monitoring conditions or standardized external excitation is denoted as... The minimum normal clamping load within the allowable range of preload parameters is denoted as... The anti-slip safety factor is denoted as Then the minimum friction stability coefficient required to meet the target working condition. for: , Meanwhile, by conducting tangential loading tests on multiple assembled samples, the lower limit of the interface equivalent friction stability coefficient was obtained when no identifiable micro-slippage occurred and the installation quality indicators remained qualified. Preset anti-slip threshold Pick and The larger value in the expression is: , When the pressure distribution dispersion satisfies And the interface equivalent friction stability coefficient satisfies At that time, it is determined that a stable mechanical coupling has been established between the fiber optic detector 6 and the structure under test 7. Threshold calibration is performed for different fiber optic detector models, elastic transfer layer materials, fixture specifications, and target monitoring conditions, and the corresponding preset uniformity threshold and preset anti-slip threshold are invoked.

[0083] S4. Standard Excitation and Signal Acquisition. After installation, a standardized external excitation is applied at a preset location near the detector. The excitation can be achieved through methods such as constant-force tapping, spring impact, step loading, micro-excitation, or frequency-sweeping micro-excitation; to improve repeatability, a constant-force exciter with a simple structure and stable triggering is preferred.

[0084] Preferably, the excitation intensity is denoted as The incentive effect is recorded at all times. The number of incentives is recorded as When multiple incentives are applied, a consistency constraint can be imposed on the intensity of each incentive to ensure that... ,in For the first Secondary incentive intensity, for The average intensity of the secondary stimulus This is the excitation consistency threshold. Correspondingly, the data acquisition unit or fiber optic demodulation equipment synchronously acquires the detector output signal. The system records information such as the excitation timestamp, excitation intensity, and number of excitations for subsequent normalization and cross-sectional comparison. The core technologies used in this step are repeatable excitation technology and synchronous sampling technology.

[0085] S5. Signal Processing and Installation Quality Assessment. This involves assessing the acquired response signals. Perform DC removal, trend removal, bandpass filtering, outlier removal, time window truncation, and windowing; then extract installation quality indicators.

[0086] Preferably, the peak amplitude is extracted within the excitation response window. Defined as the maximum absolute value of the signal within the response window, i.e.: , in, This represents the peak amplitude. This is the incentive response window.

[0087] Extract the noise floor within the unexcited noise window. Defined as the root mean square value of the signal within the unexcited window, i.e.: , in, For the first noise window Each sample value, The number of sampling points in the noise window is used as the basis for calculating the signal-to-noise ratio (SNR) based on the peak amplitude and noise floor. Defined as For the equal-length response sequence corresponding to two repeated excitations and Calculate the correlation coefficient of repeated excitation: , in, The correlation coefficient is the result of repeated excitation. and These are the first two repeated excitations corresponding to the first two excitations. Each response sample value, This represents the number of sampling points included in each stimulus-response sequence. and Let be the average values ​​of two repeated excitation response sequences, and their expressions are as follows: , , The response sequences corresponding to two repeated excitations use the same sampling frequency, response time window, and number of sampling points, and are time-aligned according to the excitation timing. When The closer the value is to 1, the more consistent the response waveforms generated by the two repeated excitations are, and the better the mechanical coupling repeatability in the current installation state; when... A decrease indicates a decline in the consistency between the two response waveforms, which may indicate fluctuations in the pre-tightening state, slight slippage of the contact interface, or deviation in the installation position.

[0088] Perform spectral analysis on the preprocessed response signal to obtain the current response spectrum, and calculate the frequency response consistency between the current response spectrum and the qualified baseline spectrum: , in, For the current response at the Spectral amplitude at each frequency point For a qualified baseline in the The spectral amplitude at each frequency point. If necessary, the main peak frequency shift can be further calculated. Preferably, ,in This represents the current peak frequency of the response. This represents the baseline peak frequency. By comparing the current metric with a threshold or acceptable baseline, previously invisible installation coupling quality can be transformed into a calculable and comparable quantitative result.

[0089] like Figure 8 As shown, the excitation diagram on the left illustrates the application location and method of the standard excitation. It is preferable to apply a constant force excitation at a preset distance from the fiber optic detector to obtain a repeatable structural response. Figure 8 The time-domain response plot in the middle is used to illustrate the peak amplitude. Noise floor and signal-to-noise ratio The method of obtaining the peak amplitude The noise floor corresponds to the maximum response amplitude within the excitation-response window. Corresponding to the background fluctuation level within the unexcited interval, It reflects the ratio of the effective response to the background noise. Figure 8 The two time-domain response curves in the middle can also be used to characterize the consistency between the responses to repeated excitations, corresponding to the correlation coefficient of repeated excitations. .like Figure 8 As shown, Figure 8 The frequency response plot on the right is used to illustrate frequency response uniformity. and main peak frequency shift The method of acquisition, in which the degree of overlap between the current response spectrum and the qualified baseline spectrum corresponds to The offset between the main peak positions corresponds to .thus, Figure 8 The excitation diagram, time-domain response, and frequency-domain response are respectively mapped to the excitation parameters, time-domain indicators, and frequency-domain indicators to form a textual correspondence.

[0090] S6. Grade Determination, Corrective Suggestions, and Result Traceability. Based on the comparison results of the above indicators, the current installation status is graded. Preferably, three levels can be set: "Qualified," "Suspicious," and "Unqualified," or expanded to four levels including "Early Warning" according to long-term operation and maintenance needs. If determined to be qualified, the measuring point is allowed to be put into use; if determined to be suspicious or unqualified, corrective suggestions corresponding to the anomaly type are output, such as reviewing the pre-tightening settings, re-cleaning the contact surface, replacing the elastic transmission layer, checking the wear of the guide components, or reinstalling. At the same time, the system binds and stores the installation parameters, interface material status, excitation method, indicator results, suggested actions, operators, and timestamps to form an auditable, verifiable, and traceable installation quality record. The judgment logic of the installation quality self-assessment is shown in Table 1.

[0091] In a preferred embodiment, this example may also introduce a "repeated disassembly and reassembly consistency assessment" mechanism. That is, after the first installation, assessment, and disassembly are completed at the same location, the installation is re-executed using the same guiding method, the same pre-tightening parameters, and the same excitation conditions, and the aforementioned assessment process is repeated to obtain the peak amplitude difference between the two installations. Correlation coefficient difference Frequency response consistency difference These are indicators. If such differences remain consistently large, it can be determined that the guide and limiting structure is worn, the pre-tightening control has excessive dispersion, the elastic transmission layer performance is degraded, or the on-site installation is unstable. Therefore, this embodiment can not only answer "whether it was installed successfully this time," but also further answer "whether this fixture can still be installed successfully after long-term use."

[0092] Example 4 This embodiment provides a self-assessment system for the installation quality of fiber optic detection fixtures. It works in conjunction with the fiber optic detection fixture in Embodiment 1 and the self-assessment method in Embodiment 2 to rapidly evaluate the mechanical coupling quality between the fiber optic detector and the structure under test in the field. The system includes a standard excitation module, a data acquisition module, an evaluation and judgment module, and a storage and traceability module. The standard excitation module and the data acquisition module are time-coordinated; the data acquisition module is connected to the evaluation and judgment module; and the evaluation and judgment module is connected to the storage and traceability module. These modules can be integrated into a single portable device, or they can be formed by combining independent standard exciters, fiber optic demodulation equipment, edge computing terminals, and host computer software.

[0093] The standard excitation module is used to apply controlled, standardized external excitation at predetermined excitation locations on the structure under test and to record the excitation parameters. The standard excitation module can be configured as a mechanical impact type, a spring-energy storage type, or an electric micro-excitation type to generate constant-force impacts, spring impacts, step loading, micro-excitation, or frequency-sweeping micro-excitation. The standard excitation module records the excitation timestamp and excitation intensity for each excitation. And the number of incentives, and control the intensity of each incentive to be within the range of the average incentive intensity. The deviation should not exceed the excitation consistency threshold to ensure consistency between multiple excitations.

[0094] The data acquisition module connects to the fiber optic demodulation equipment or signal acquisition circuit to simultaneously acquire the response signal output by the fiber optic detector while a standardized external excitation is applied by the standard excitation module. The data acquisition module samples, synchronizes, buffers, and performs preliminary preprocessing on the response signal, and associates the response signal with the corresponding excitation timestamp, excitation intensity, and excitation count. By synchronously associating the excitation information with the response signal, the correspondence between subsequent installation quality indicators and specific excitation events can be guaranteed.

[0095] The evaluation and judgment module performs DC removal, detrending, bandpass filtering, outlier removal, time window truncation, and windowing on the response signal output by the data acquisition module. It then extracts at least one of the following as installation quality indicators from the preprocessed response signal: peak amplitude, noise floor, signal-to-noise ratio, repetitive excitation correlation coefficient, frequency response consistency, and main peak frequency offset. The evaluation and judgment module compares each installation quality indicator with its corresponding preset threshold, or compares the current response spectrum with the qualified baseline spectrum for similarity, and outputs an installation quality level of "qualified," "questionable," or "unqualified" based on the comparison results. When the installation quality level is "questionable" or "unqualified," the evaluation and judgment module outputs corresponding corrective suggestions based on the type of out-of-bounds indicator, including reviewing pre-tightening parameters, cleaning contact surfaces, replacing the elastic transmission layer, checking the wear of the guide limit structure, or reinstallation.

[0096] The evaluation and judgment module also includes a baseline management submodule and a rule update submodule. The baseline management submodule stores and maintains qualified sample templates for different fiber optic detector models, fixture specifications, and tested structure scenarios. Qualified sample templates include qualified baseline spectra and installation quality index thresholds corresponding to that scenario. The rule update submodule updates the thresholds and judgment rules for different scenarios based on historical installation evaluation results, enabling the evaluation and judgment module to call the corresponding evaluation rules based on the fiber optic detector model, fixture specifications, and tested structure type. For batch deployment scenarios, the evaluation and judgment module can also generate a point list and quality status information based on the installation quality level of each measurement point to identify measurement points with installation risks.

[0097] The storage and traceability module is used to bind and store installation parameters, interface material status, excitation parameters, installation quality indicators, installation quality level, correction suggestions, and measurement point information to form a traceable installation quality record. Installation parameters include the type of mating surface, guide positioning results, preload displacement, preload torque, or clamping load; interface material status includes the material type, number of uses, and replacement records of the elastic transfer layer; excitation parameters include the excitation method, excitation timestamp, excitation intensity, and number of excitations. The storage and traceability module can also output installation quality evaluation results to a host computer or mobile terminal for on-site personnel to review and manage.

[0098] In one specific implementation, each fiber optic probe fixture or fiber optic detector is equipped with a QR code, RFID tag, or electronic identification code. After the installer scans the identification code, the storage and traceability module retrieves the historical installation records, the number of times the flexible transfer layer has been replaced, and the most recent installation quality evaluation result for the corresponding fixture or fiber optic detector. The evaluation data generated during this installation is then written into the historical record under the corresponding identification code, thereby establishing a link between the fixture, fiber optic detector, measurement point information, and installation quality records.

[0099] The working process of this embodiment is as follows: the standard excitation module applies standardized external excitation at a predetermined excitation position on the structure under test and records the excitation parameters simultaneously; the data acquisition module acquires the response signal of the fiber optic detector under the standardized external excitation and associates the response signal with the excitation parameters; the evaluation and judgment module preprocesses the response signal, extracts installation quality indicators, and outputs the installation quality level and correction suggestions based on a preset threshold or qualified baseline; the storage and traceability module binds and stores the installation parameters, interface material status, excitation parameters, evaluation results, and measurement point information. Through the collaborative work of the above modules, the system can quantitatively evaluate the installation quality of the fiber optic detection fixture and form a verifiable, auditable, and traceable installation quality record.

[0100] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A fiber optic detection fixture, characterized in that, Includes a clamping base, clamping assembly, guide and limiting structure, pre-tightening and limiting structure, and elastic transmission layer; The fixture base is provided with an installation area for placing the fiber optic detector, and the lower surface of the fixture base is provided with a mating surface that is adapted to the surface of the structure being measured. The clamping assembly is mounted on the fixture base, with the pressure-applying end of the clamping assembly facing the installation area, and forming a closed-loop force distribution with the fixture base through the installation area; The guide limiting structure is disposed on at least one of the clamp base and the clamping assembly, and is located on the side, end or in a position corresponding to the package of the fiber optic detector in the mounting area, so as to limit at least two degrees of freedom of the fiber optic detector in the lateral, axial and attitude directions. The pre-tightening limiting structure is disposed on the locking path between the clamp base and the clamping assembly to limit the pre-tightening displacement, pre-tightening torque or clamping load of the clamping assembly. The elastic transfer layer is disposed at at least one contact interface between the fiber optic detector and the structure under test and between the fiber optic detector and the clamping assembly.

2. The fiber optic detection fixture according to claim 1, characterized in that, The guide and limiting structure includes at least one of the following: V-shaped guide groove, double-sided retaining edge, anti-rotation shoulder, end face positioning step, and pin hole type auxiliary positioning component; The V-shaped guide groove, double-sided retaining edge, anti-rotation shoulder, end face positioning step, and pin hole auxiliary positioning component are set on the clamp base and / or clamping assembly and located on the periphery of the installation area, for jointly constraining the lateral position, axial position, and attitude angle of the fiber optic detector.

3. The optical fiber detection fixture according to claim 1, characterized in that, The clamping assembly includes a pressure plate or a pressure cap, which is connected to the clamp base by fasteners, and the end of the pressure plate or pressure cap facing the installation area forms a pressure end; The pressure end is provided with a swinging pressure head or a floating pressure block. The swinging pressure head swings relative to the pressure plate or pressure cap within a preset angle range. The floating pressure block is used to move along the pressing direction within a limited range and to perform lateral displacement or posture adjustment. The pressure application position of the clamping component is set to correspond to the encapsulation or non-sensitive bearing area of ​​the fiber optic detector.

4. The optical fiber detection fixture according to claim 1, characterized in that, The pre-tightening limiting structure includes one or more of the following: a travel limiting element, a torque limiting element, and a constant force limiting element disposed on the locking path between the clamp base and the clamping assembly; The stroke limiting element includes a limiting sleeve, a stepped stop, and a set of position shims, used to limit the maximum compression displacement of the clamping assembly; the torque limiting element includes a torque limiting fastener, a torque wrench, or a fastening assembly with a slippage structure, used to limit the maximum locking torque of the clamping assembly; the constant force limiting element includes a disc spring assembly, a spring plate, a wave washer, and an elastic column, used to apply an elastic load to the clamping assembly within a preset working displacement range. The stroke limiting element, torque limiting element, and constant force limiting element are disposed on the locking path between the clamp base and the clamping assembly.

5. The fiber optic detection fixture according to claim 4, characterized in that, The elastic transfer layer is disposed on at least one side of the fiber optic detector. The elastic transfer layer is composed of a thin elastic pad, a high-friction micro-textured sheet, a fiber-reinforced elastic sheet, or a multilayer composite material. The elastic transfer layer is replaceable relative to the clamp base and the clamping assembly. The thickness of the elastic transfer layer is 0.1 mm to 2 mm.

6. A self-assessment method for the installation quality of an optical fiber detection fixture, based on the optical fiber detection fixture of claim 1, characterized in that, include: S1. Obtain the surface information of the neighborhood of the target measurement point of the structure under test, select the contact surface type of the fixture base and configure the elastic transfer layer according to the surface information; S2. Place the fiber optic detector into the fixture base, and constrain the position and attitude of the fiber optic detector through the guide and limiting structure so that the fiber optic detector falls into the preset position window. S3. The pre-tightening limit structure is used to perform parameterized pre-tightening control on the clamping assembly, so that the pre-tightening parameters fall into the preset range, and a stable mechanical coupling compensated by the elastic transfer layer is established between the fiber optic detector and the structure under test or between the clamping assemblies. S4. Apply a standardized external excitation near the fiber optic detector and simultaneously acquire the response signal of the fiber optic detector; S5. Preprocess the response signal, extract the installation quality index, and compare the installation quality index with the preset threshold or qualified baseline. S6. Based on the comparison results, determine the current installation status level, output correction suggestions, and bind and store the installation parameters, interface material status, index results and measurement point information to form an installation quality traceability record.

7. The self-assessment method for the installation quality of an optical fiber detection fixture according to claim 6, characterized in that, The configuration of the elastic transfer layer includes acquiring surface contour data, local curvature, installation reachable space size, and target measurement point position of the neighborhood of the target measurement point of the structure under test. A preset length installation window is selected with the target measurement point as the center. The contour data within the installation window is fitted and calculated to obtain the local radius of curvature and flatness deviation. The installation scenario type is determined by adaptability judgment based on flatness deviation, local radius of curvature and installation space size. The installation scenario type includes planar installation scenario, curved surface installation scenario and irregular or restricted installation scenario. Select the type of mating surface of the clamp base based on the determined installation scenario, and select the clamping components and elastic transfer layer in combination with the fiber optic detector package size, sensitive direction and target monitoring type.

8. The self-assessment method for the installation quality of an optical fiber detection fixture according to claim 6, characterized in that, The establishment of a stable mechanical coupling compensated by the elastic transmission layer includes pre-tightening control of the clamping assembly by at least one of a stroke limiting element, a torque limiting element, and a constant force elastic element. The preload displacement, preload torque, or clamping load is used as the preload parameter, and the preload parameter is controlled within the corresponding preset range. The clamping load satisfies the following within the working displacement range: ， An elastic transfer layer is incorporated to compensate for microscopic surface irregularities at the contact interface, thereby obtaining the pressure distribution dispersion within the contact area. and the equivalent friction stability coefficient of the interface ,when and At that time, it is determined that a stable mechanical coupling has been established; in, To clamp the load, The target is clamped with a load. To determine the allowable fluctuation threshold of the clamping load, To preset the uniformity threshold, This is the preset anti-slip threshold.

9. The self-assessment method for the installation quality of an optical fiber detection fixture according to claim 6, characterized in that, The comparison of installation quality indicators with preset thresholds or qualified baselines includes performing DC removal, trend removal, bandpass filtering, outlier removal, time window truncation, and windowing on the response signal to obtain a preprocessed response signal. The peak amplitude, noise floor, signal-to-noise ratio, repetitive excitation correlation coefficient, and frequency response consistency are extracted from the preprocessed response signal and used as installation quality indicators. Multiple parameters of the installation quality indicators are compared with their corresponding preset thresholds, and the degree of matching between the current response spectrum and the qualified baseline spectrum is determined based on the frequency response consistency. The expression for the frequency response consistency is: ， in, For frequency response consistency, For the number of frequency points, The current response spectrum is at the 1st Spectral amplitude at each frequency point For the qualified baseline spectrum in the first Spectral amplitude at each frequency point.

10. A self-assessment system for the installation quality of an optical fiber detection fixture, comprising the method described in claim 6, characterized in that, include: The module includes a standard incentive module, a data acquisition module, an evaluation and judgment module, and a storage and traceability module. The standard excitation module is used to apply controlled, standardized external excitation at predetermined excitation locations on the structure under test and to record the excitation parameters. The data acquisition module is connected to the fiber optic demodulation equipment or signal acquisition circuit to synchronously acquire the response signal output by the fiber optic detector under standardized external excitation, and to sample, synchronize, buffer and preprocess the response signal. The evaluation and judgment module is connected to the data acquisition module and is used to extract installation quality indicators based on the preprocessed response signal, compare the installation quality indicators with preset thresholds or qualified baselines, and output installation quality level and correction suggestions based on the comparison results. The storage traceability module is connected to the evaluation and judgment module and is used to bind and store installation parameters, interface material status, excitation parameters, installation quality indicators, installation quality level, correction suggestions and measurement point information to form a traceable installation quality record.

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