Irradiation-resistant sensor gelling-free assembling and packaging method based on tenon-and-mortise structure

Abstract

The invention relates to the technical field of optical fiber sensing, and discloses an irradiation-resistant sensor gelling-free assembling and packaging method based on a tenon-and-mortise structure, which comprises the following steps: step 1, wiping a to-be-packaged fiber bragg grating with anhydrous alcohol to remove floating dust and scraps, putting the fiber bragg grating into an ultrasonic cleaning instrument filled with deionized water for cleaning, and then putting the fiber bragg grating into the ultrasonic cleaning instrument; and 2, fixing the lower assembly of the packaging structure on a packaging fixing system, placing the fiber bragg grating on a fiber groove self-locking structure reserved between the lower assembly and the upper assembly, and enabling the fiber bragg grating to be located at the center of the lower assembly. By adopting an all-metal tantalum packaging structure and through mortise and tenon mechanical interlocking and gelling-free sealing design, monitoring failure caused by aging and creeping of colloid is thoroughly avoided, the service life of the sensor in a radiation environment is remarkably prolonged, meanwhile, monitoring failure caused by aging and creeping of the colloid is thoroughly avoided, and the service life of the sensor in a radiation environment is prolonged. And the service life of the sensor in a radiation environment is obviously prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic sensing, and specifically to a non-glue assembly and encapsulation method for radiation-resistant sensors based on the mortise and tenon structure. Background Art

[0002] In radiation environments such as space, nuclear reactors, and high-energy physics laboratories, it is difficult to observe the abnormal heating and deformation of high-precision instruments. As an advanced tool for structural health monitoring, fiber optic sensing technology shows significant application prospects. Especially FBG sensors have become a widely popular choice due to their convenience and efficiency. However, bare FBG sensors are extremely vulnerable to damage under external loads. Therefore, their encapsulation process is particularly crucial before engineering application deployment. Traditional FBG sensor encapsulation methods include substrate surface mounting, coating, and tube encapsulation. Substrate surface mounting encapsulation has single-sided exposure and simply cannot provide radiation protection for fiber optic sensors. Coating encapsulation is restricted by material properties and coating production, and has weak radiation resistance. Tube glue encapsulation has obvious encapsulation gaps, causing high-energy particles to enter through the tube openings, damaging the FBG sensors, and the service life will be greatly shortened due to the creep and aging of the glue.

[0003] However, bare fiber Bragg grating (FBG) sensors are extremely vulnerable to damage under external loads. Existing FBG sensor encapsulation methods have many defects. For example, substrate surface mounting encapsulation cannot provide radiation protection, tube glue encapsulation has encapsulation gaps and glue aging and creep problems, and coating encapsulation has weak radiation resistance and complex preparation, all of which cannot meet the radiation resistance requirements. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a non-glue assembly and encapsulation method for radiation-resistant sensors based on the mortise and tenon structure, which solves the problem of the short service life of sensors in a radiation environment.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A non-glue assembly and encapsulation method for radiation-resistant sensors based on the mortise and tenon structure, including the following steps:

[0006] Step 1: Wipe the fiber Bragg grating to be encapsulated with anhydrous alcohol to remove dust and debris. Place the fiber Bragg grating in an ultrasonic cleaner filled with deionized water for cleaning, and use nitrogen to dry it after cleaning.

[0007] Step 2: Fix the lower assembly of the encapsulation structure on the encapsulation fixing system. Place the fiber Bragg grating on the fiber groove self-locking structure reserved between the lower assembly and the upper assembly, and make the fiber Bragg grating located exactly in the center of the lower assembly. Mark the position of the fiber in contact with the bare fiber at the assembly position with a marker pen.

[0008] Step 3: Fix one end of the fiber optic cable of the fiber Bragg grating, apply prestress to the other end of the fiber optic cable and then fix it. Then, combine the upper assembly and the lower assembly on the encapsulation structure.

[0009] Step 4: Use a high-carbon steel hammer to drive four customized tenons into the pre-positioned mortise holes in the upper and lower assemblies in sequence until the tenons appear below the lower assembly.

[0010] Step 5: Remove the fixation, take out the encapsulated sensor, use a grinder to grind off most of the protruding parts of the tenons, and then use sandpapers of different thicknesses for fine grinding to form a fully metal encapsulation structure.

[0011] Preferably, the fiber Bragg grating is a pure silica fiber FBG written by femtosecond laser. The coating layer is retained during writing, and the contact position in the fiber groove is marked to ensure the centering and positioning of the FBG.

[0012] Preferably, the encapsulation structure includes tenons, an upper assembly and a lower assembly. The tenons play a role of mechanical locking in the assembly. The tenons are made of tantalum metal. The upper assembly and the lower assembly form a self-locking structure for the fiber groove, and self-locking structures for the fiber groove are provided on the opposite sides of the upper assembly and the lower assembly.

[0013] Preferably, the self-locking structure for the fiber groove includes a semi-circular hole groove. The self-locking structure for the fiber groove places and clamps the optical fiber. Optical fiber hole grooves are provided on both the upper and lower sides of the inner diameter of the semi-circular hole groove, and the semi-circular hole groove communicates with the optical fiber hole grooves.

[0014] Preferably, two dovetail tenons are fixedly connected to the opposite side of the lower assembly and the upper assembly. Two dovetail grooves are provided on the opposite side of the upper assembly and the lower assembly. The two dovetail tenons are engaged with the two dovetail grooves.

[0015] Preferably, the tenons are slightly deformed on the lower side of the lower assembly, filling the mortise holes and having a certain extension outward, even wrapping the lower surface of the lower assembly.

[0016] Preferably, when the radiation dose of the encapsulation structure is ≥10 6 Gy, the radiation-induced drift of the FBG wavelength is <20% of that of the traditional glue-sealed structure, and the temperature sensitivity is ≥12 pm / °C.

[0017] Preferably, both the upper assembly and the lower assembly are made of tantalum metal.

[0018] Preferably, the purity of the tantalum metal is >99.9%. After the surface of the encapsulation structure is polished, it forms a cylinder with a diameter error ≤0.1 mm and a surface roughness Ra <1.6 μm.

[0019] Preferably, the radiation resistance performance of the all-metal encapsulation structure is quantified through modeling and simulation, including the following steps:

[0020] Establish an encapsulation model based on the lattice stability parameters of tantalum metal;

[0021] Simulate the influence of radiation on the refractive index of FBG and the central wavelength of the reflection spectrum;

[0022] Combine the peak data of FBG after radiation-induced attenuation to correct the real-time drift error of the environmental monitoring value.

[0023] Working principle: (no serial number).

[0024] The present invention provides a glue-free assembly and encapsulation method for a radiation-resistant sensor based on a mortise and tenon structure. It has the following beneficial effects:

[0025] 1. By adopting an all-metal tantalum encapsulation structure, through mortise and tenon mechanical interlocking and glue-free sealing design, combined with the high density, lattice stability of tantalum metal and the deformation filling of tenons, the monitoring failure caused by colloid aging and creep is completely avoided, the service life of the sensor in a radiation environment is significantly extended, and at the same time, the monitoring failure caused by colloid aging and creep is completely avoided, and the service life of the sensor in a radiation environment is significantly extended.

[0026] 2. The all-metal encapsulation structure of the present invention effectively shortens the temperature response time, reduces the loss of thermal stress tensile transmission, significantly improves the temperature sensing sensitivity, and through modeling and simulation in a radiation environment, accurately obtains the radiation-induced drift amount, realizes real-time and accurate monitoring of external changes in a radiation environment, and ensures the accuracy of monitoring data.

[0027] 3. The mortise and tenon structure of the present invention simplifies the processing and assembly process. At the same time, the tantalum metal encapsulation takes into account high temperature resistance and corrosion resistance, with high-precision surface grinding, reduces the operation difficulty and cost, improves the production efficiency, is convenient for integrated installation, enables the fiber optic sensor to be distributed in various strong radiation environments such as space, nuclear industry, and high-energy physics laboratories, and thus has a wider scope of application. Description of the Drawings

[0028] Figure 1 It is a schematic flow chart of the glue-free assembly and encapsulation method for a radiation-resistant sensor based on a mortise and tenon structure of the present invention;

[0029] Figure 2 It is a schematic diagram of the all-metal encapsulation structure of the glue-free assembly and encapsulation method for a radiation-resistant sensor based on a mortise and tenon structure of the present invention;

[0030] Figure 3 It is an exploded view of the all-metal encapsulation structure of the present invention;

[0031] Figure 4Schematic diagram of the lower assembly of the all-metal encapsulation structure of the present invention;

[0032] Figure 5 Schematic diagram of the upper assembly of the all-metal encapsulation structure of the present invention;

[0033] Figure 6 Schematic diagram of the tenon nail of the all-metal encapsulation structure of the present invention;

[0034] Figure 7 For the present invention Figure 4 Schematic diagram at position A in

[0035] Wherein, 1. Lower assembly; 2. Upper assembly; 3. Mortise hole; 4. Dovetail groove; 5. Dovetail tenon; 6. Semi-circular hole groove; 7. Tenon nail; 8. Optical fiber hole groove. Specific embodiments

[0036] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Embodiment:

[0038] Please refer to the attached Figure 1 - attached Figure 7 , the embodiment of the present invention provides a glue-free assembly and encapsulation method for a radiation-resistant sensor based on a tenon-mortise structure, including the following steps:

[0039] Step 1, at the moment when the encapsulation operation is started, first select the fiber grating to be encapsulated, carefully wipe it with anhydrous alcohol to thoroughly remove the floating dust and debris on the surface. After completing this preliminary cleaning, place the fiber grating in an ultrasonic cleaner filled with deionized water, and use the high-frequency vibration of ultrasonic waves to conduct a more in-depth and comprehensive cleaning of the fiber grating. After the cleaning work is completed, use nitrogen to blow-dry it to ensure that there is no water stain residue on the surface of the fiber grating and it is in an ideal state of cleanliness and dryness;

[0040] Step 2, next, fix the lower assembly 1 of the encapsulation structure on the encapsulation fixing system. Then, place the fiber grating on the fiber groove self-locking structure reserved between the lower assembly 1 and the upper assembly 2, and make the fiber grating located at the exact center position of the lower assembly 1. To further ensure the accuracy of positioning, clearly mark the optical fiber at the contact position between the assembly and the bare fiber with a marker pen;

[0041] Step 3: First, fix one side of the pigtail of the fiber grating, then apply prestress to the other side of the pigtail. After the prestress application is completed, combine the upper assembly 2 and the lower assembly 1 of the encapsulation structure to ensure that the fiber grating is in an appropriate stress state within the encapsulation structure, thereby ensuring its stability and reliability;

[0042] Step 4: On the basis of the successful completion of the above operations, pick up a high-carbon steel hammer and knock four customized tantalum metal tenons 7 into the mortise holes 3 reserved in the upper and lower assemblies 1 in sequence and orderly. During the knocking process, continue the operation until the tenon 7 is clearly visible below the lower assembly 1;

[0043] Step 5: When the tenon 7 reaches the expected position, remove the fixing device and take off the encapsulated sensor. Subsequently, use a grinder to grind off most of the protruding part of the tenon 7. After this preliminary treatment, then use sandpapers of different thicknesses for fine grinding to finally shape the all-metal encapsulation structure.

[0044] The fiber grating used in the encapsulation process is a pure silica fiber FBG written by femtosecond laser. During the writing process, the coating layer is retained to enhance the mechanical strength and anti-external damage ability of the fiber grating. Moreover, during the process of putting the fiber into the fiber groove, by making mark signs at the contact positions, it can accurately ensure that the FBG is in a centered position.

[0045] The encapsulation structure includes tenons 7, an upper assembly 2 and a lower assembly 1. Among them, the tenons 7 play a role of mechanical locking in the assembly. The tenons 7 are made of tantalum metal. The upper assembly 2 and the lower assembly 1 form a self-locking structure for the fiber groove, and self-locking structures for the fiber groove are provided on both opposite sides of the upper assembly 2 and the lower assembly 1.

[0046] The tenons 7 play a role of mechanical locking. Tantalum metal has excellent radiation resistance and mechanical strength, can effectively resist the erosion of radiation, and provides a strong locking force for the encapsulation structure. The self-locking structure of the fiber groove is to further enhance the fixing effect on the fiber grating, prevent it from moving accidentally during use. At the same time, the self-locking structure of the fiber groove forms a barb structure that is easy to enter but difficult to exit, making it difficult for the fiber to displace inside it, so as to achieve the effect of fixing the grating position.

[0047] The self-locking structure of the fiber groove includes a semi-circular hole groove 6. The self-locking structure of the fiber groove places and clamps the fiber. Fiber hole grooves 8 are opened on both the upper and lower sides of the inner diameter of the semi-circular hole groove 6, and the semi-circular hole groove 6 and the fiber hole grooves 8 communicate with each other.

[0048] Two dovetail tenons 5 are fixedly connected to the opposite side of the lower assembly 1 and the upper assembly 2. Two dovetail grooves 4 are opened on the opposite side of the upper assembly 2 and the lower assembly 1. Both of the two dovetail tenons 5 are engaged with the two dovetail grooves 4.

[0049] It can greatly enhance the tightness and stability of the connection between the upper assembly 2 and the lower assembly 1, prevent relative sliding or separation between the assemblies, ensure the integrity of the encapsulation structure, and the special shapes of the dovetail tenons 5 and dovetail grooves 4 can provide good guiding and locking functions, making the assembly process more accurate and convenient.

[0050] The tenon nail 7 made of tantalum metal will produce slight deformation under the lower assembly 1. This deformation enables the tenon nail 7 to not only fully fill the mortise hole 3, but also extend outward to a certain extent, and even tightly wrap the lower surface of the lower assembly 1, thus greatly improving the sealing performance and mechanical strength of the encapsulation structure.

[0051] When the radiation dose of the encapsulation structure is ≥ 10 6 Gy in the environment, the radiation-induced drift of the FBG wavelength is < 20% of that of the traditional glue-sealed structure, and the temperature sensitivity is ≥ 12 pm / ℃.

[0052] It can maintain a stable working state in a high-radiation environment and provide accurate temperature monitoring data, meeting the application requirements in an extreme radiation environment, providing technical support for the monitoring and control of related equipment. Through optimized encapsulation structure design, material selection, and glue-free assembly, the influence of radiation on the fiber Bragg grating is reduced, and the sensitivity of temperature response is improved.

[0053] Both the upper assembly 2 and the lower assembly 1 are made of tantalum metal.

[0054] Both the upper assembly 2 and the lower assembly 1 are made of tantalum metal with a purity greater than 99.9%. After the encapsulation structure is fabricated, its surface is finely polished to form a cylindrical shape. And strictly control the diameter error within 0.1 mm to ensure that the surface roughness Ra is less than 1.6 μm to meet the requirements of high precision and high performance.

[0055] The purity of tantalum metal > 99.9%. The surface of the encapsulation structure forms a cylinder after grinding, the diameter error ≤ 0.1 mm, and the surface roughness Ra < 1.6 μm.

[0056] The high-purity tantalum metal ensures the performance consistency and reliability of the material, while the fine polishing treatment makes the encapsulation structure have good appearance and dimensional accuracy, improves the radiation resistance and optical performance of the encapsulation structure, reduces signal loss and interference caused by surface unevenness, meets the requirements of high-precision measurement and application, improves the overall quality of the encapsulation structure. The high purity reduces the influence of impurities on the material performance, while the precise dimensions and smooth surface contribute to the transmission of light and the protection against radiation.

[0057] The radiation resistance of the all-metal encapsulation structure is quantified by modeling and simulation, including the following steps:

[0058] Establish a packaging model based on the lattice stability parameters of tantalum metal;

[0059] Simulate the influence of radiation on the refractive index of FBG and the central wavelength of the reflection spectrum;

[0060] Combine the FBG peak data after radiation-induced attenuation to correct the real-time drift error of the environmental monitoring value.

[0061] Through modeling and simulation, it is possible to predict and evaluate the performance of the packaging structure before actual application, provide a scientific basis for the design and optimization of the packaging structure, improve the R & D efficiency and product quality. It lies in accurately quantifying the radiation resistance performance, providing data support for performance evaluation and error correction in actual application, and simulating and analyzing the process of interaction between radiation and materials based on physical principles and mathematical models.

[0062] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A non-glue assembly and packaging method for radiation-resistant sensors based on a mortise and tenon structure, characterized in that: The following steps are involved: Step 1: wipe the packaged fiber Bragg grating with anhydrous alcohol to remove dust and debris, put the fiber Bragg grating into an ultrasonic cleaner filled with deionized water for cleaning, and blow dry it with nitrogen after cleaning; Step 2: fix the lower assembly (1) of the packaging structure on the packaging fixing system, place the fiber grating on the fiber groove self-locking structure reserved between the lower assembly (1) and the upper assembly (2), and make the fiber grating be located in the center of the lower assembly (1), and mark the position of the optical fiber at the contact position between the assembly and the bare fiber with a marker pen; Step 3, fix the pigtail on one side of the fiber grating, apply prestress to the pigtail on the other side and fix it, and then combine the upper assembly (2) and the lower assembly (1) of the packaging structure; Step 4: Use a high carbon steel hammer to knock four customized dowels (7) into the reserved mortise holes (3) of the upper and lower assemblies (1) in sequence according to the pre-positions, until the dowels (7) appear below the lower assembly (1); Step 5: Remove the fixation, take down the packaged sensor, use a grinder to grind off most of the protruding parts of the dowel (7), and then use sandpaper of different coarseness and fineness to finely grind it to form a full metal packaging structure.

2. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1 is characterized in that: The fiber grating is a pure quartz fiber FBG inscribed by a femtosecond laser, the coating layer is retained during inscription, and the contact position in the fiber groove is marked to ensure the centering of the FBG.

3. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1 is characterized in that: The packaging structure comprises a dowel (7), an upper assembly (2) and a lower assembly (1), wherein the dowel (7) plays a role of mechanical locking in the assembly, the dowel (7) is made of metal tantalum material, the upper assembly (2) and the lower assembly (1) are combined to form a fiber optic groove self-locking structure, and the upper assembly (2) and the lower assembly (1) are both provided with a fiber optic groove self-locking structure on opposite sides.

4. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1, characterized in that: The optical fiber groove self-locking structure comprises a semicircular hole groove (6), the optical fiber groove self-locking structure places the optical fiber and clamps the optical fiber, the inner diameter of the semicircular hole groove (6) is provided with optical fiber hole grooves (8) on both upper and lower sides, and the semicircular hole groove (6) and the optical fiber hole groove (8) are interconnected.

5. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1, characterized in that: Two dovetail tenons (5) are fixedly connected to one side of the lower assembly (1) and the upper assembly (2), and two dovetail grooves (4) are provided on one side of the upper assembly (2) and the lower assembly (1), and the two dovetail tenons (5) are mutually engaged with the two dovetail grooves (4).

6. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1, characterized in that: The dowel (7) is slightly deformed on the lower side of the lower assembly (1), filling the mortise hole (3) while extending outward to a certain extent, and even wrapping the lower side surface of the lower assembly (1).

7. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1, characterized in that: The packaging structure has a radiation dose of ≥10 6 In the Gy environment, the FBG wavelength radiation drift is less than 20% of the traditional glue sealing structure, and the temperature sensitivity is ≥12pm / ℃.

8. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 7, characterized in that: The upper assembly (2) and the lower assembly (1) are both made of metal tantalum.

9. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1, characterized in that: The purity of the metal tantalum is greater than 99.9%, and the surface of the packaging structure is polished to form a cylinder with a diameter error of ≤0.1 mm and a surface roughness Ra of <1.6 μm.

10. The method for assembling and packaging a radiation-resistant sensor based on a mortise and tenon structure without adhesive according to claim 1, characterized in that: The radiation resistance performance of the all-metal packaging structure is quantified by modeling and simulation, including the following steps: A packaging model is established based on the lattice stability parameters of metal tantalum; Simulate the effect of radiation on the FBG refractive index and the central wavelength of the reflection spectrum; Combined with the FBG peak data after radiation attenuation, the real-time drift error of the environmental monitoring value is corrected.

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