High-sensitivity dynamic strain sensor based on phase shift grating

Abstract

The utility model discloses a high-sensitivity dynamic strain sensor based on a phase shift grating. The high-sensitivity dynamic strain sensor comprises a base. The base is fixedly connected with a fixed seat; a sliding seat is slidably connected to the base; wherein an optical cable is arranged above the fixed seat and the sliding seat, and a fiber bragg grating is arranged on the optical cable; the sliding seat is in sliding connection with the sliding groove of the base through the sliding block with the ball, so that sliding friction is reduced, and deformation of the base caused by dynamic strain of a tested structure can be sensitively responded; the relative displacement of the fixed seat and the sliding seat enables the fiber bragg grating on the optical cable to deform, the central wavelength of the reflection or transmission spectrum of the fiber bragg grating shifts, and an external demodulation system can accurately calculate the dynamic strain according to the central wavelength; meanwhile, the pressing plate and the bottom groove stably press the optical cable, so that relative slippage of the optical cable is avoided, accuracy and sensitivity of strain transmission are ensured, and high-precision measurement of dynamic strain of a measured structure can be realized.

Description

Technical Field

[0001] This utility model relates to a high-sensitivity dynamic strain sensor based on a phase-shifting grating, belonging to the field of strain sensor technology. Background Technology

[0002] Dynamic strain monitoring is of great significance in fields such as bridges, machinery, and building structures, as it can reflect the stress state and health status of structures in real time. Fiber Bragg grating (FBG) sensors are widely used in strain monitoring due to their advantages such as resistance to electromagnetic interference, corrosion resistance, and high sensitivity. However, existing FBG dynamic strain sensors often suffer from problems such as low strain transfer efficiency, inconvenient installation and adjustment, and insufficient stability under high vibration environments, affecting monitoring accuracy and reliability.

[0003] The present invention aims to provide a high-sensitivity dynamic strain sensor based on a phase-shifting grating. Utility Model Content

[0004] To address the aforementioned technical shortcomings, the purpose of this invention is to provide a high-sensitivity dynamic strain sensor based on a phase-shifting grating, which improves strain transmission efficiency and monitoring stability, and adapts to the needs of different application scenarios.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a high-sensitivity dynamic strain sensor based on a phase-shifting grating, comprising:

[0006] Base;

[0007] The fixing seat is fixedly connected to the base;

[0008] A sliding seat, which is slidably connected to the base;

[0009] An optical cable is provided above the fixed base and the sliding base, and a fiber optic grating is provided on the optical cable.

[0010] Preferably, both the fixed seat and the sliding seat are provided with bottom grooves for accommodating optical cables, and both the fixed seat and the sliding seat are provided with pressure plates above them for pressing the optical cables into the corresponding bottom grooves.

[0011] Preferably, gaskets are fixed inside the bottom groove and below the pressure plate.

[0012] Preferably, the surface of the gasket is provided with anti-slip texture.

[0013] Preferably, the pressure plate is fixed to the fixed seat or the sliding seat by locking bolts.

[0014] Preferably, the base has circular mounting holes on both sides of the end near the fixed seat, and waist-shaped mounting holes on both sides of the end away from the fixed seat, and fixing bolts are provided in both the circular mounting holes and the waist-shaped mounting holes.

[0015] Structural adhesive is fixedly adhered to the bottom wall of the sliding seat.

[0016] Preferably, the base has grooves on both sides, and sliders are fixed on both sides of the sliding seat, with the sliders slidably connected in the grooves on the same side.

[0017] Preferably, the slider is provided with balls on both the upper and lower sides to reduce friction.

[0018] Preferably, an adjusting screw is engaged with the base, one end of the adjusting screw is fixed with a hexagonal drive head, and the end of the adjusting screw away from the hexagonal drive head is provided with a smooth rod;

[0019] The sliding seat has a through hole, and the optical rod passes through the through hole and is fixed with a stop block.

[0020] Preferably, the diameter of the through hole is larger than the diameter of the guide rod.

[0021] Compared with existing technologies:

[0022] 1. The sliding seat of this utility model is slidably connected to the base groove by a ball-bearing slider, which reduces sliding friction and can sensitively respond to the deformation of the base caused by the dynamic strain of the measured structure; the relative displacement between the fixed seat and the sliding seat causes the fiber grating on the optical cable to deform, resulting in a shift in the center wavelength of its reflection or transmission spectrum, which the external demodulation system can use to accurately calculate the magnitude of dynamic strain; at the same time, the pressure plate and the bottom groove smoothly press the optical cable, avoiding relative slippage of the optical cable, ensuring the accuracy and sensitivity of strain transmission, and enabling high-precision measurement of the dynamic strain of the measured structure.

[0023] 2. This utility model adjusts the initial position of the sliding seat by adjusting the lead screw, and applies appropriate preload to the optical cable to make the fiber grating work in the optimal linear range of sensitivity, thus avoiding failure of small strain monitoring; the structural adhesive enhances the stability of the sliding seat, and the adjustment of the lead screw does not affect the dynamic displacement of the sliding seat, making the fiber grating sensitive to small strain changes, and further improving the accuracy of dynamic strain measurement. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of this utility model;

[0025] Figure 2 This is an exploded view of the optical cable, bottom groove, and pressure plate of this utility model;

[0026] Figure 3This is an exploded view of the bottom groove, pressure plate, and gasket of this utility model;

[0027] Figure 4 This is a schematic diagram of the structure of this utility model from another perspective;

[0028] Figure 5 This is an exploded cross-sectional view of the base and sliding seat of this utility model;

[0029] Figure 6 This is a cross-sectional view of the base, sliding seat, adjusting screw, and guide rod of this utility model.

[0030] In the picture:

[0031] 1. Base; 101. Circular mounting hole; 102. Waist-shaped mounting hole; 103. Slide groove;

[0032] 2. Fixed base; 3. Sliding base; 301. Slider;

[0033] 4. Optical fiber cable; 5. Fiber Bragg grating;

[0034] 6. Bottom groove; 7. Pressure plate; 8. Gasket; 9. Locking bolt;

[0035] 10. Fixing bolts; 11. Structural adhesive;

[0036] 12. Ball bearings;

[0037] 13. Adjusting screw; 1301. Hexagonal drive head; 1302. Smooth rod; 1303. Stop block. Detailed Implementation

[0038] The present invention is illustrated below with specific embodiments, but these are not intended to limit the scope of the invention.

[0039] Example 1

[0040] like Figures 1-6 As shown in the figure, this embodiment provides a high-sensitivity dynamic strain sensor based on a phase-shifting grating, including a base 1, a fixed base 2, a sliding base 3, an optical cable 4, and a fiber optic grating 5. The fixed base 2 is fixedly connected to the base 1, and the sliding base 3 is connected to the base 1 through a sliding structure; the optical cable 4 is disposed above the fixed base 2 and the sliding base 3, and the phase-shifting fiber optic grating 5 is integrated on the optical cable 4.

[0041] Both the fixed base 2 and the sliding base 3 have bottom grooves 6 for accommodating the optical cable 4, and pressure plates 7 are provided on top of each. The pressure plates 7 are fixed by locking bolts 9, pressing the optical cable 4 into the bottom groove 6. Gaskets 8 are fixed in the bottom groove 6 and under the pressure plates 7 to prevent the optical cable 4 from being damaged by direct contact with hard metal. The base 1 has sliding grooves 103 on both sides, and sliders 301 are fixed on both sides of the sliding base 3. The sliders 301 are slidably connected in the sliding grooves 103, and ball bearings 12 are provided on both the upper and lower sides of the sliders 301 to reduce sliding friction.

[0042] Work process:

[0043] When the structure under test generates dynamic strain, the strain is transmitted to the base 1 through the connecting structure, causing the base 1 to undergo slight deformation along with the structure under test. Since the fixed seat 2 is rigidly connected to the base 1, the position of the fixed seat 2 remains stable; while the sliding seat 3 can slide relative to the deformation of the base 1 within the sliding groove 103. The ball bearings 12 on the slider 301 significantly reduce the sliding friction resistance, ensuring that the sliding seat 3 can respond sensitively to strain changes.

[0044] The relative displacement between the fixed seat 2 and the sliding seat 3 causes tensile or compressive deformation in the optical cable 4 between them, which is directly transmitted to the fiber optic grating 5 on the optical cable 4. The grating pitch of the fiber optic grating 5 changes with the deformation, causing a shift in the center wavelength of its reflected or transmitted spectrum. The external demodulation system acquires the spectral signal of the fiber optic grating 5 in real time, and the dynamic strain of the measured structure can be accurately calculated by analyzing the wavelength shift. Throughout the process, the smooth pressing of the pressure plate 7 and the bottom groove 6 ensures that there is no relative slippage of the optical cable 4, guaranteeing the accuracy and sensitivity of strain transmission.

[0045] Example 2

[0046] This embodiment, based on Embodiment 1, focuses on optimizing the installation and adjustment structure, including the design of the mounting holes in the base 1 and the structure of the adjusting screw 13. Circular mounting holes 101 are provided on both sides of the end of the base 1 closest to the fixed seat 2, and oblong mounting holes 102 are provided on both sides of the end furthest from the fixed seat 2. Fixing bolts 10 are installed in both the circular mounting holes 101 and the oblong mounting holes 102; structural adhesive 11 is fixedly adhered to the bottom wall of the sliding seat 3.

[0047] An adjusting screw 13 is engaged with the base 1. One end of the adjusting screw 13 is fixed with a hexagonal drive head 1301, and the other end is provided with a smooth rod 1302. A through hole 302 is opened on the sliding seat 3. The smooth rod 1302 passes through the through hole 302 and is fixed with a stop block 1303. The diameter of the through hole 302 is larger than the diameter of the smooth rod 1302.

[0048] Assembly steps:

[0049] After completing the basic structure assembly in Example 1, one end of the base 1 is initially fixed to the structure under test by the fixing bolt 10 in the circular assembly hole 101.

[0050] According to the installation location requirements, adjust the position of the other end of the base 1 through the waist-shaped mounting hole 102, and tighten the corresponding fixing bolt 10 after alignment to achieve stable installation of the base 1.

[0051] By rotating the adjusting screw 13 through the hexagonal drive head 1301, the sliding seat 3 is pushed to make a fine adjustment of its position through the meshing transmission between the adjusting screw 13 and the base 1, so as to adjust the pre-tightening force of the optical cable 4. After the adjustment is completed, the gap between the optical rod 1302 and the through hole 302 ensures that the sliding seat 3 can freely respond to dynamic strain.

[0052] Remove the protective paper from the structural adhesive 11 on the bottom wall of the slide block 3, and gently push the slide block 3 to make its bottom fit against the structure being tested. After the structural adhesive 11 cures, it will enhance the stability of the slide block 3.

[0053] Work process:

[0054] During installation, the circular mounting hole 101 ensures the precise positioning of the mounting base 2, while the oblong mounting hole 102 allows the base 1 to adjust its installation position within a certain range to adapt to the installation requirements of different tested structures. The adjusting screw 13 precisely adjusts the initial position of the sliding seat 3. By applying appropriate preload to the optical cable 4, the fiber optic grating 5 operates within its optimal linear range of sensitivity, preventing small strain monitoring failure due to insufficient initial tension.

[0055] During dynamic strain monitoring, after the strain of the measured structure is transferred to the base 1, the sliding seat 3, with the assistance of structural adhesive 11, responds to the deformation of the measured structure and can slide flexibly under strain. Since the diameter of the through hole 302 is larger than the diameter of the optical rod 1302, the adjusting screw 13 does not restrict the dynamic displacement of the sliding seat 3, but only serves as an initial pre-tightening adjustment. The fiber optic grating 5, in the pre-tightened state, is more sensitive to minute strain changes, and the spectral wavelength shift is more significant, allowing the demodulation system to achieve higher precision dynamic strain measurement.

[0056] Example 3

[0057] This embodiment is designed for applications involving high vibration and strong impact, and enhances the stability of the optical cable fixing and the reliability of the sliding structure based on Embodiment 1. The core structure includes the basic components of Embodiment 1, wherein the surface of the gaskets 8 is provided with anti-slip textures.

[0058] Assembly steps:

[0059] Referring to the assembly process of Example 1, focus on checking whether the anti-slip texture of the gasket 8 is clear and complete, and ensure that the gasket 8 is in close contact with the optical cable 4;

[0060] When installing the pressure plate 7, use a torque wrench to tighten the locking bolt 9 to the preset torque, so that the optical cable 4 is firmly clamped by the anti-slip texture, avoiding the optical cable slippage caused by vibration.

[0061] Work process:

[0062] In a high-vibration environment, the vibration of the measured structure is transmitted to the various components of the sensor through the base 1. Because the anti-slip texture on the surface of the pad 8 increases the friction with the optical cable 4, even under strong vibration, the optical cable 4 can remain stable between the bottom groove 6 and the pressure plate 7 without relative slippage, ensuring that the strain energy is completely transmitted to the fiber optic grating 5.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate and not limit the technical solutions of this utility model. Although this utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to this utility model without departing from the spirit and scope of this utility model. Any modifications or partial substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A high-sensitivity dynamic strain sensor based on a phase-shifting grating, characterized in that, include: Base (1); A fixed base (2) is fixedly connected to a base (1); A sliding seat (3) is slidably connected to a base (1); An optical cable (4) is provided above the fixed seat (2) and the sliding seat (3), and a fiber optic grating (5) is provided on the optical cable (4).

2. The high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 1, characterized in that, Both the fixed seat (2) and the sliding seat (3) are provided with bottom grooves (6) for accommodating optical cables (4), and pressure plates (7) for pressing optical cables (4) into the corresponding bottom grooves (6) are provided above the fixed seat (2) and the sliding seat (3).

3. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 2, characterized in that, Gaskets (8) are fixed inside the bottom groove (6) and below the pressure plate (7).

4. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 3, characterized in that, The surface of each pad (8) is provided with anti-slip texture.

5. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 3, characterized in that, The pressure plate (7) is fixed to the fixed seat (2) or the sliding seat (3) by locking bolts (9).

6. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 1, characterized in that, The base (1) has circular mounting holes (101) on both sides of the end near the fixed seat (2), and waist-shaped mounting holes (102) on both sides of the end away from the fixed seat (2). Fixing bolts (10) are provided in both the circular mounting holes (101) and the waist-shaped mounting holes (102). Structural adhesive (11) is fixedly adhered to the bottom wall of the sliding seat (3).

7. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 1, characterized in that, The base (1) has grooves (103) on both sides, and sliders (301) are fixed on both sides of the sliding seat (3). The sliders (301) are slidably connected in the grooves (103) on the same side.

8. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 7, characterized in that, The slider (301) is provided with balls (12) on both the upper and lower sides to reduce friction.

9. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 7, characterized in that, An adjusting screw (13) is engaged with the base (1). A hexagonal drive head (1301) is fixed at one end of the adjusting screw (13), and a light rod (1302) is provided at the end of the adjusting screw (13) away from the hexagonal drive head (1301). The sliding seat (3) has a through hole (302), and the light rod (1302) passes through the through hole (302) and is fixed with a stop block (1303).

10. A high-sensitivity dynamic strain sensor based on a phase-shifting grating according to claim 9, characterized in that, The diameter of the through hole (302) is larger than the diameter of the smooth rod (1302).

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