Fiber grating deflection sensing system and manufacturing method thereof

Abstract

The invention discloses a fiber bragg grating deflection sensing system and a manufacturing method thereof, the fiber bragg grating deflection sensing system comprises a multi-layer carbon fiber belt reinforced matrix, the carbon fiber belt reinforced matrix is formed by superposing at least two layers of unidirectional carbon fiber prepreg belts or dry carbon fiber fabrics, and the at least two layers of carbon fiber belts are used for clamping a fiber bragg grating therebetween; a low-rigidity sensing window area is arranged on the carbon fiber belt reinforced matrix; the fiber bragg grating sensing unit comprises at least a plurality of fiber bragg gratings which are accurately and axially arranged between the at least two layers of carbon fiber prepreg tapes; the low-rigidity sensing window areas correspond to the fiber bragg gratings in number and position; the coating further comprises strong interface bonding glue; fiber leads at two ends of the fiber grating are led out from the end part of the sensing system; according to the system, the high rigidity of the cross-laid carbon fiber matrix in the measurement direction is matched with the strain concentration effect of the low-rigidity window area and the efficient strain transmission of the low-modulus glue to the FBG, so that high sensitivity and excellent linearity are realized through the combined action of the high rigidity, the strain concentration effect and the efficient strain transmission of the low-modulus glue to the FBG.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber devices and systems, in particular to a distributed deflection sensing system based on fiber Bragg grating, which is suitable for long-term deformation monitoring of flexible structures such as bridges, large-span roofs, wind turbine blades, etc. BACKGROUND

[0002] Optical fiber deflection sensing system is a sensing technology that uses the change of optical signal caused by the bending (deflection) of optical fiber to measure physical quantities (such as displacement, pressure, deformation, vibration, etc.). It is an important branch of optical fiber sensors. Due to its advantages such as anti-electromagnetic interference, corrosion resistance, high sensitivity, and distributed measurement, it is widely used in industrial monitoring, structural health diagnosis, medical equipment, etc.

[0003] The system includes a sensing optical fiber and an integrated FBG sensitive structure. When the optical fiber is bent, the light signal transmitted inside will change, mainly in the following aspects: light intensity loss (micro-bending loss), bending causes part of the light to leak from the core to the cladding (radiation loss), and the light intensity at the receiving end is weakened. The amount of loss is directly related to the bending radius and the number of bends. Wavelength shift (such as FBG bending sensitivity), the grating pitch of fiber Bragg grating (FBG) changes when it is bent, and the reflected wavelength shifts. Mode interference changes (such as Mach-Zehnder interference), bending changes the optical path difference of different modes in the optical fiber, affecting the interference fringes.

[0004] Problems of existing deflection sensors: 1. Resistance strain gauge: susceptible to electromagnetic interference, short service life, frequent calibration required, difficult to measure in a distributed manner. 2. Traditional fiber grating sensor: direct sticking or packaging method easily leads to low strain transmission efficiency, large hysteresis, and significant temperature cross-sensitivity; the stiffness and thermal expansion coefficient of the packaging material (such as metal, single polymer) do not match the base structure, affecting the measurement accuracy and long-term stability; weak in shear and torsion resistance. 3. Some carbon fiber-based sensors: mostly single-layer or simple composite, failing to fully utilize the anisotropy advantages of carbon fiber; stress concentration at the bonding interface easily leads to failure of fiber grating or non-linear measurement. There is an urgent need for a deflection sensing system with high sensitivity, good linearity, strong anti-interference, excellent long-term stability, easy installation, and good compatibility with composite material base. SUMMARY

[0005] The present application provides a fiber grating deflection sensing system and a manufacturing method thereof. The high stiffness of the cross-laminated carbon fiber base in the measurement direction, combined with the strain concentration effect of the low stiffness window area, and the high strain transmission of the low modulus glue to the FBG, work together to achieve high sensitivity and excellent linearity, thereby solving the problems raised in the background technology.

[0006] To achieve the above purpose, the present application provides the following technical scheme: a fiber grating deflection sensing system, The system comprises: a multi-layer carbon fiber tape reinforced base, the carbon fiber tape reinforced base is formed by stacking at least two layers of unidirectional carbon fiber prepreg tape or dry carbon fiber fabric, and at least two layers of carbon fiber tape are arranged to clamp an optical fiber Bragg grating therebetween; The carbon fiber tape reinforced base is provided with a low-rigidity sensing window area; The system further comprises an optical fiber grating sensing unit: comprising at least a plurality of optical fiber Bragg gratings, which are arranged axially between the at least two layers of carbon fiber prepreg tapes; The low-rigidity sensing window area corresponds to the number and position of the optical fiber Bragg gratings; The system further comprises a strong interfacial bonding glue; Optical fiber leads at both ends of the optical fiber grating are led out from the ends of the sensing system.

[0007] Preferably, the fiber directions of adjacent carbon fiber layers are cross-laid, so as to improve the axial rigidity of the sensor base in the measurement direction, and to enhance the rigidity perpendicular to the measurement direction and the resistance to torsion and lateral shear.

[0008] Preferably, the low-rigidity sensing window area is realized by reducing the corresponding fiber density, specifically, the carbon fiber tape for adhering to the measured object has a two-layer structure, and the fiber tapes are combined by fibers of different angles, that is, the two layers of carbon fiber tapes form the low-rigidity sensing window area at the positions corresponding to the optical fiber Bragg gratings by using fibers of lower density, and then are bonded by resin.

[0009] Preferably, the carbon fiber tapes not adhering to the measured structure also comprise two layers of cross-laid fiber tapes, and the two layers of cross-laid fibers have a fiber spacing greater than that of the carbon fiber tapes adhering to the measured structure.

[0010] Preferably, the system further comprises a gradient modulus polyurethane adhesive bonding system: a polyurethane adhesive is used to firmly bond the multi-layer carbon fiber tapes and the embedded optical fiber gratings into one.

[0011] In the core bonding area close to the optical fiber grating, a low-modulus polyurethane adhesive with low modulus and high elongation is used, and in the area far from the FBG, a high-modulus polyurethane adhesive is used.

[0012] Preferably, nano-silica particles treated by a silane coupling agent are added to the polyurethane adhesive, and the nano-silica particles are uniformly distributed.

[0013] Preferably, the system further comprises an encapsulation and protection layer, and a flexible polyurethane protection layer is coated or molded on the outside of the cured sensor body.

[0014] Preferably, the system further comprises a mounting structure, and fixed clamping plates are designed at both ends of the sensor, which fix the four corners and both ends of the carbon fiber tapes.

[0015] Preferably, a thin low-modulus polyurethane pressure-sensitive adhesive layer is pre-coated on the surface of the sensor to be attached to the surface of the structure to be measured, and is covered with release paper.

[0016] A dynamic monitoring method based on the fiber grating deflection sensing system of any one of the above, comprising the following steps: S1, layer preparation: laying multiple layers of carbon fiber tape according to the designed intersection angle; S2, fiber positioning: precisely tensioning and fixing the FBG-equipped fiber to the center line of the window area; S3, gradient glue application: precisely point coating / spraying low-modulus polyurethane glue around the FBG and in the vicinity of the carbon fiber interface area, and coating medium-high modulus polyurethane glue in the remaining carbon fiber layer area; S4, hot pressing and curing: placing the layer into a mold and applying controllable pressure, with slightly lower pressure in the window area; S5, using a stepwise temperature rising curing process: first, heat preservation at a low temperature to make the low-modulus glue fully flow and infiltrate the fiber and carbon fiber; then, rising to the complete curing temperature of the polyurethane glue for final crosslinking; S6, post-processing: demolding, applying a protective layer, installing a fixed clamping plate, coating a pressure-sensitive adhesive layer, and performing optical performance calibration.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1. The high stiffness of the cross-laid carbon fiber substrate in the measurement direction, the strain concentration effect of the low stiffness window area, and the high strain transmission of the low-modulus glue to the FBG work together to achieve high sensitivity and excellent linearity.

[0018] 2. The excellent anti-creep property of carbon fiber, the optimized stress distribution of the gradient modulus polyurethane glue, and the enhanced interface bonding of the nano filler work together to ensure the long-term reliable operation of the sensor in harsh environments.

[0019] 3. The cross-laid layer greatly improves the anti-torsion and anti-shear ability, and suppresses interference in the non-measurement direction.

[0020] 4. The gradient modulus glue layer and the nano filler enhanced interface significantly improve the anti-delamination, anti-aging and anti-fatigue performance.

[0021] 5. The design of the low-modulus polyurethane pressure-sensitive adhesive layer greatly simplifies the on-site installation.

[0022] 6. The carbon fiber substrate is light and strong, and the polyurethane glue is flexible, which is easy to co-cure or post-paste with composite structures, and has strong compatibility.

[0023] 7. Distributed / quasi-distributed measurement can be realized: a single fiber can be connected with multiple sensors to realize long-distance deflection distribution monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic view of the front structure of the present application; Figure 2 is a schematic view of the top structure of the present application; Figure 3 is a schematic view of the top structure of the low stiffness sensing window area of the present application; Figure 4 is a schematic view of the top structure of the upper layer of the double-layer carbon fiber tape of the present application; Figure 5 is a schematic view of the top structure of the lower layer of the double-layer carbon fiber tape of the present application; Figure 6 is a schematic view of the structure of the external carbon fiber tape of the present application; Figure 7 is a schematic view of the structure of the polyurethane adhesive bonding of the present application; Figure 8 is a schematic view of the structure of the gradient modulus polyurethane adhesive bonding system of the present application; Figure 9 is a schematic view of the structure of the nano-silica particles of the present application; Figure 10 is a schematic view of the structure of the flexible polyurethane protective layer of the present application; Figure 11 is a schematic view of the structure of the fixed clamping plate of the present application; Figure 12 is a schematic view of the structure of the low modulus polyurethane pressure-sensitive adhesive layer of the present application.

[0025] In the figure: 1, carbon fiber tape reinforced matrix; 2, low stiffness sensing window area; 3, fiber Bragg grating; 4, optical fiber lead; 5, gradient modulus polyurethane adhesive bonding system; 5a, low modulus polyurethane adhesive; 5b, high modulus polyurethane adhesive; 6, nano-silica particles; 7, flexible polyurethane protective layer; 8, fixed clamping plate; 9, low modulus polyurethane pressure-sensitive adhesive layer. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Example 1, please refer to Figures 1-3 The present application provides a fiber grating deflection sensing system, The carbon fiber tape reinforced matrix 1 is composed of at least two (preferably 3-5) layers of unidirectional carbon fiber prepreg tape or dry carbon fiber fabric, at least two layers of carbon fiber tape are arranged to sandwich the fiber Bragg grating 3 therebetween, and the fiber grating is sandwiched between the two layers of carbon fiber tape, which has the following advantages: Excellent mechanical protection: resistance to impact and extrusion: carbon fiber has extremely high strength and stiffness, providing a strong physical barrier for the fragile fiber grating inside, effectively preventing damage such as crushing, excessive bending, scratching, etc. caused by installation, use or accidental impact.

[0028] Resistance to wear and tear: the carbon fiber layer protects the optical fiber from external environmental friction, wear and tear.

[0029] Keep the optical fiber straight: the sandwich structure helps to keep the optical fiber straight and straight during the curing process and subsequent use, which is essential to ensure the accuracy and consistency of strain measurement.

[0030] Moisture and chemical corrosion resistance: the carbon fiber tape and the cured resin matrix form a sealed or semi-sealed environment, isolating the fiber grating from moisture, salt spray, grease, fuel, solvents and other environmental factors that may erode the optical fiber coating or affect the performance of the adhesive, greatly improving the long-term stability and durability of the sensor in harsh environments.

[0031] A low-stiffness sensing window area 2 is provided in the carbon fiber tape reinforced matrix 1, which can be achieved by locally reducing the number of carbon fiber layers, using more sparse carbon fiber fabric, or locally reducing the curing pressure, and the low-stiffness sensing window area 2 is the main bending deformation sensitive area.

[0032] It also includes a fiber grating sensing unit FBG: including at least a plurality of fiber Bragg gratings 3, arranged axially between at least two layers of carbon fiber prepreg tape.

[0033] Further, the low-stiffness sensing window area 2 corresponds to the number and position of the fiber Bragg gratings 3, and the fiber Bragg gratings 3 are arranged at the center position of the low-stiffness sensing window area 2.

[0034] This can achieve good strain transfer efficiency: when the structure to be measured deforms, the carbon fiber tape in the low-stiffness sensing window area 2 can effectively transfer the strain to the fiber grating sandwiched therebetween.

[0035] Also included is strong interface bonding, usually co-cured or secondary bonding during manufacturing process, the resin can infiltrate the carbon fiber tape and fiber Bragg grating, forming a solid interface, which makes the fiber Bragg grating can be very sensitive and accurate to perceive the strain on the carbon fiber tape imposed by the host structure. Physical clamping plus resin bonding, greatly reduces the possibility of fiber slipping relative to the matrix under strain load, improves measurement reliability.

[0036] The optical fiber leads 4 at both ends of the fiber Bragg grating are drawn out from the sensor end.

[0037] The fiber Bragg grating sensing system is connected with an external conventional demodulator and data analysis software, wherein the fiber sensor is used for collecting deflection information and converting the deflection information into optical information; the demodulator is used for interpreting the fiber sensor information and transmitting the information to the upper computer software; and the software is used for deflection conversion and boundary condition correction. In operation, the fiber Bragg grating 3 provides stable light signal input through the optical fiber leads 4, and common light sources include a broadband light source such as a superluminescent diode (SLD) and a tunable light source. When the monitored substrate changes, the refractive index and length of the underlying fiber Bragg grating 3 change, causing the wavelength of the reflected light to shift. This wavelength shift has a one-to-one correspondence with the change in physical quantity, so the displacement change of the substrate can be sensed by measuring the wavelength shift. The light signal emitted by the light source is transmitted to the fiber Bragg grating 3, and the reflected light signal of the sensor is transmitted back to the demodulation unit. The demodulation unit is responsible for converting the reflected light signal of the sensor into an electrical signal and demodulating the wavelength shift. Demodulation techniques include filtering method, interference method, and tunable narrow-band light source method. The electrical signal output by the demodulation unit is further processed and analyzed, including signal amplification, filtering, analog-to-digital conversion, and subsequent data processing and analysis, so as to monitor the shift caused by the deformation of the substrate.

[0038] Please refer to Figure 3 As an embodiment of the present application, the fiber directions of adjacent carbon fiber layers are cross-laid at a specific angle (such as 0° / 90°, 0° / 45° / 90°). This not only greatly improves the axial stiffness of the sensor substrate in the measurement direction, usually the 0° direction, ensuring high sensitivity and linearity; but also significantly enhances the stiffness perpendicular to the measurement direction, the 90° direction, and the anti-twisting and anti-lateral shear capacity, effectively suppressing the interference of non-measurement direction deformation on the FBG signal, improving the measurement purity and accuracy.

[0039] Please refer to Figures 4-5As an embodiment of the present application, the low stiffness sensing window area 2 is achieved by reducing the corresponding fiber density, specifically, the fiber bragg grating 3 used for the carbon fiber tape attached to the measured object is a two-layer structure; and the fiber tape is a combination of fibers of different angles, that is, the two-layer carbon fiber tape forms a low stiffness sensing window area 2 at the position corresponding to the fiber bragg grating 3 by using fibers with low density, and then is bonded by resin.

[0040] In this way, on the one hand, the stiffness and the anti-torsion and anti-lateral shear ability are improved, and on the other hand, the fibers are arranged in the same direction, and the low stiffness sensing window area 2 formed by the carbon fiber tape is effective in transmitting the strain to the attached fiber grating.

[0041] Please refer to Figure 6 As an embodiment of the present application, the carbon fiber tape of the non-attached measurement structure of the fiber bragg grating 3 also includes two layers of intersecting fiber tapes, and the fiber spacing of the two layers of intersecting fibers is greater than that of the carbon fiber tape of the attached measurement structure. In this way, the outer fiber tape of the non-attached measurement structure is more likely to deform than the inner fiber tape, because when deformation occurs, the outer layer tends to deform more, and the deformation is conducted from the attached structure surface to the non-attached surface, so that the non-attached surface can deform more while reducing the extrusion on the inner fiber bragg grating 3, avoiding damaging the fiber bragg grating 3, and thus achieving efficient measurement.

[0042] Please refer to Figures 7-8 As an embodiment of the present application, the system further includes a gradient modulus polyurethane adhesive bonding system 5: a polyurethane adhesive is used to firmly bond the multi-layer carbon fiber tape and the embedded fiber grating into one.

[0043] Gradient modulus design: in the core bonding area close to the fiber grating, a low modulus polyurethane adhesive 5a with low modulus and high elongation is used, and the modulus is close to or slightly higher than the fiber coating, which ensures that the micro-strain of the substrate can be efficiently and low-loss transmitted to the FBG, reduces the hysteresis, improves the sensitivity, and protects the fragile FBG from stress concentration damage.

[0044] In the interlayer area of the carbon fiber away from the FBG, a high modulus polyurethane adhesive 5b is used, and the modulus is close to the carbon fiber epoxy resin matrix, which ensures the strong interfacial bonding strength between the multi-layer carbon fiber tape and the overall structure and the overall structure stiffness between the sensor and the measured structure, and ensures the long-term stability of strain transmission.

[0045] Please refer to Figure 9As an embodiment of the present application, the nano-silica particles 6 treated by silane coupling agent are added to the polyurethane adhesive, and the nano-silica particles 6 are uniformly distributed. The filler not only improves the thermal conductivity of the adhesive layer, accelerates the curing and improves the temperature uniformity, reduces the thermal residual stress; more importantly, the surface treatment significantly enhances the chemical bonding and mechanical interlocking between the polyurethane adhesive and the surface of the carbon fiber and the optical fiber coating, greatly improving the interface durability and fatigue resistance.

[0046] Please refer to Figure 7 As an embodiment of the present application, it further includes a packaging and protective layer. A flexible polyurethane protective layer 7 or a thin weather-resistant polymer film / metal foil is coated or molded on the outside of the cured sensor body, providing physical protection, insulation and anti-humidity, chemical medium environmental corrosion resistance. The protective layer material needs to be compatible with the polyurethane adhesive.

[0047] Please refer to Figure 8 As an embodiment of the present application, a fixed clamping plate 8 is designed at both ends of the sensor to fix the four corners and both ends of the carbon fiber tape, which is convenient for cooperation with the bolt fixed by high-strength adhesive with the structure to be measured.

[0048] Please refer to Figure 9 As an embodiment of the present application, a thin low-modulus polyurethane pressure-sensitive adhesive layer 9 is pre-coated on the surface of the structure to be measured on the bottom surface of the sensor, and is covered with release paper. When installed on site, the release paper is torn off to quickly bond and position, and then mechanical fixation or secondary pouring is assisted, which greatly simplifies the installation process, improves the efficiency and ensures the initial bonding quality.

[0049] The present application provides a manufacturing method of the fiber grating deflection sensing system as described in any one of the above, comprising the following steps: S1, layer preparation: laying multiple layers of carbon fiber tape according to the designed cross angle, and forming a low-stiffness sensing window area at a predetermined position; S2, fiber positioning: accurately tensioning and fixing the FBG-equipped fiber on the center line of the window area, and leaving a loose space at the lead-out end of the fiber, so that the fiber is not torn when the structure to be measured deforms; S3, gradient glue application: accurately point coating / spraying low-modulus polyurethane adhesive 5a around the FBG and in the adjacent carbon fiber interface area, and coating medium-high modulus polyurethane adhesive 5b in the remaining carbon fiber layer area; ensure that the adhesive layer is evenly covered without bubbles; S4, hot pressing and curing: placing the laid layer into a mold and applying a controllable pressure, and the pressure in the window area is slightly lower; S5, using a stepwise temperature curing process: first, at a lower temperature (e.g. 60-80°C), to allow the low modulus glue to flow and infiltrate the optical fiber and carbon fiber; then, to the complete curing temperature of the polyurethane glue (e.g. 100-120°C) for final cross-linking, which optimizes the interface infiltration and reduces internal stress; S6, post-processing: demolding, applying a protective layer 7, installing a fixed clamping plate 8 or coating a pressure-sensitive adhesive layer 9, and performing optical performance calibration.

[0050] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A fiber Bragg grating deflection sensing system, characterized in that: include: A multi-layer carbon fiber tape reinforced matrix (1), wherein the carbon fiber tape reinforced matrix (1) is formed by stacking at least two layers of unidirectional carbon fiber prepreg tapes or dry carbon fiber fabrics, and at least two layers of carbon fiber tapes are provided for sandwiching the fiber Bragg grating (3) therebetween; A low-rigidity sensing window area (2) is provided on a carbon fiber tape reinforced matrix (1); Also included is a fiber Bragg grating sensing unit comprising at least a plurality of fiber Bragg gratings (3) precisely and axially arranged between at least two layers of carbon fiber prepreg tapes; The low-rigidity sensing window region (2) corresponds to the number and position of the fiber Bragg gratings (3); Also includes strong interface bonding adhesive; The optical fiber leads (4) at both ends of the optical fiber Bragg grating are led out from the end of the sensing system.

2. The fiber Bragg grating deflection sensing system according to claim 1, characterized in that: The fiber directions of adjacent carbon fiber layers are cross-laid to improve the axial stiffness of the sensor matrix in the measuring direction, while also enhancing the stiffness perpendicular to the measuring direction and the ability to resist torsional and lateral shearing.

3. The fiber Bragg grating deflection sensing system according to claim 2, characterized in that: The low-rigidity sensing window area (2) is achieved by reducing the corresponding fiber density. Specifically, the carbon fiber tape used for the fiber Bragg grating (3) to fit the measured object has a two-layer structure; and the fiber tape is a combination of fibers crossed at different angles, that is, the two layers of carbon fiber tape form the low-rigidity sensing window area (2) at the position corresponding to the fiber Bragg grating (3) through the fibers with lower density, and then are bonded by resin.

4. The fiber Bragg grating deflection sensing system according to claim 3, characterized in that: The carbon fiber tape of the non-bonded measurement structure of the fiber Bragg grating (3) also includes two layers of crossed fiber tapes, and the fiber spacing formed by the two layers of crossed fibers is larger than the fiber spacing of the carbon fiber tape of the bonded measurement structure.

5. The fiber Bragg grating deflection sensing system according to claim 1, characterized in that: The system also includes a gradient modulus polyurethane adhesive bonding system (5): using polyurethane adhesive to firmly bond the multi-layer carbon fiber tape and the optical fiber Bragg grating embedded therein into one; In the core bonding area close to the fiber Bragg grating, a low modulus polyurethane glue (5a) with low modulus and high elongation is used, and in the carbon fiber interlayer area away from the FBG, a high modulus polyurethane glue (5b) is used.

6. The fiber Bragg grating deflection sensing system according to claim 1, characterized in that: Nano-silica particles (6) treated with a silane coupling agent are added to the polyurethane adhesive, and the nano-silica particles (6) are evenly distributed.

7. The fiber Bragg grating deflection sensing system according to claim 1, characterized in that: The system also includes a packaging and protective layer, wherein a flexible polyurethane protective layer (7) is coated or molded on the outside of the cured sensor body.

8. The fiber Bragg grating deflection sensing system according to claim 1, characterized in that: The system also includes a mounting structure, wherein fixed clamps (8) are designed at both ends of the sensor, and the fixed clamps fix the four corners and both ends of the carbon fiber strip.

9. The fiber Bragg grating deflection sensing system according to claim 1, characterized in that: A thin layer of low modulus polyurethane pressure-sensitive adhesive (9) is pre-coated on the bottom surface of the sensor in contact with the surface of the structure to be measured, and is covered with release paper.

10. A method for manufacturing a fiber Bragg grating deflection sensing system according to any one of claims 1 to 9, characterized in that: The steps include: S1, layup preparation: laying multiple layers of carbon fiber tapes at designed cross angles; S2, fiber positioning: precisely tighten and fix the fiber with FBG to the center line of the window area; S3, gradient sizing: accurately spot-coat / spray low-modulus polyurethane glue around the FBG and near the carbon fiber interface area, and apply medium- and high-modulus polyurethane glue to the remaining carbon fiber interlayer areas; S4, hot press curing: the laminate is placed into the mold and controlled pressure is applied, with slightly lower pressure in the window area; S5, using a step-by-step temperature-raising curing process: first, keep the temperature low to allow the low-modulus adhesive to fully flow and soak the optical fiber and carbon fiber; then raise the temperature to the full curing temperature of the polyurethane adhesive for final cross-linking; S6, post-processing: demoulding, applying a protective layer, installing a fixed splint, applying a pressure-sensitive adhesive layer, and calibrating the optical properties.

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