A method and apparatus for optical fiber implant monitoring of composite pressure vessels

Abstract

This invention relates to a method and device for monitoring fiber optic implantation in composite material pressure-bearing equipment, belonging to the field of composite material structure monitoring and intelligent sensing technology. The method integrates distributed or point-type fiber optic sensors synchronously with the composite material through a designed winding process, enabling real-time monitoring of state parameters such as strain, temperature, and pressure in key areas of the equipment. Embedded guide rails and intelligent cable laying devices are used to ensure the stability and accuracy of the fiber optic cable during installation. A multi-layered structure design, including flexible fiber optic coating and elastic coupling layers, improves the fiber optic cable's durability and coupling efficiency. A temperature-stress collaborative monitoring system integrates FBG, Brillouin, and Raman sensing to achieve high-precision multi-physics sensing. This invention features high integration, low modification costs, and excellent monitoring performance, and is suitable for online health monitoring and intelligent early warning of composite material pressure-bearing equipment such as cryogenic high-pressure hydrogen storage cylinders, carbon fiber type V cylinders, and composite material pressure pipelines.

Description

Technical Field

[0001] This invention relates to the field of composite material pressure-bearing equipment and sensor monitoring technology, and in particular to a fiber optic implantation monitoring method and device for composite material pressure-bearing equipment. Background Technology

[0002] Composite materials have been widely used in aerospace, energy, and chemical industries due to their advantages such as high strength, lightweight, flexible design, and environmental friendliness. Composite material pressure equipment typically needs to operate under complex conditions such as high pressure, high temperature, or low temperature. Although composite material structures have the advantages of being lightweight and high-strength, they are prone to localized damage, delamination, and leakage risks during long-term service. These problems seriously affect the safety and reliability of the equipment.

[0003] Traditional external sensing monitoring methods, such as strain gauges and ultrasonic testing, suffer from drawbacks such as unstable signals, numerous blind spots, and single-point monitoring, making it difficult to meet the needs of pressure equipment for overall status information and real-time online health monitoring. Furthermore, in low-temperature conditions, the reliability and measurement accuracy of ordinary sensors can be severely affected. Fiber optic sensing technology, with its resistance to harsh environments, electromagnetic interference, high sensitivity, and distributed monitoring capabilities, has become the ideal choice for intelligent monitoring of pressure equipment.

[0004] Embedding fiber optic sensors into the composite material winding process enables monitoring of the internal state of the equipment. This embedded monitoring method allows for real-time monitoring of parameters such as strain, temperature, and pressure of the composite material structure during manufacturing and service, enabling timely detection of potential damage and defects, and improving the safety and reliability of the equipment. However, existing technologies lack fiber optic implantation solutions suitable for various composite material pressure-bearing equipment, and the integration of fiber optic implantation with the winding process is poor. Specifically, there is a lack of independent fiber tension control mechanisms, leading to breakage or micro-bending during winding; a lack of guiding tracks and other limiting devices, resulting in path deviation and insufficient laying accuracy; the absence of flexible interface materials or elastic coupling layers between the fiber and the substrate, leading to unstable bonding and strain transfer; improper selection of embedding layer positions, often placing them in locations with high stress or environmental influence; and simple outlet packaging structures, making it difficult to adapt to complex working conditions over long periods. This application achieves dual control of path and tension by introducing embedded guiding tracks and high-precision intelligent wire release devices, adding flexible interface materials and elastic coupling layers between the fiber and the substrate, optimizing the embedding layer positions, and employing multi-layer sealing and buffer protection for the outlet packaging, effectively improving the integration of the fiber and the winding process and its long-term reliability. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the background art by proposing a fiber optic implantation monitoring method and device for composite material pressure-bearing equipment. By combining the winding process with fiber optic implantation technology, real-time and accurate monitoring of the equipment under complex operating conditions can be achieved, enabling timely detection of abnormal conditions such as low-temperature heat leakage and structural damage, thereby improving the safety and intelligence level of pressure-bearing equipment.

[0006] The technical solution of the present invention, a method for monitoring fiber optic implantation in composite material pressure-bearing equipment, includes the following specific steps:

[0007] S1. Determine the fiber optic implantation path based on the structural and stress distribution characteristics of composite material pressure-bearing equipment;

[0008] S2. During the composite material winding process, the optical fiber is synchronously embedded into the winding layer using a guiding device;

[0009] S3. An elastic coupling layer is formed between the flexible interface material and the composite matrix;

[0010] S4. After winding, a multi-layer sealing structure is set for optical fiber lead-out.

[0011] S5. Based on the fiber optic demodulation system, temperature and strain monitoring is performed on composite material pressure-bearing equipment to achieve real-time perception, diagnosis and early warning of equipment health status.

[0012] Step S1 calculates the structural characteristics and stress distribution of the composite material pressure-bearing equipment through theoretical calculations and / or finite element simulations, and determines the principal stress concentration area and potential failure area; based on the principal stress concentration area and potential failure area, plans the optical fiber implantation path; wherein, the optical fiber implantation path is laid out along the principal stress direction to cover the monitoring area; the optical fiber path in step S1 selects the matching optical fiber type and layout method according to the physical field characteristics to be monitored by the equipment, and its layout strategy is determined based on characteristic parameters such as principal stress direction, high strain gradient area, shear failure risk area, and significant thermal-stress coupling area.

[0013] Specifically, based on the structural characteristics and load types of composite material pressure-bearing equipment, the stress distribution law of the equipment under typical service conditions is determined through a combination of theoretical modeling and finite element analysis. The theoretical analysis, based on pressure vessel mechanics and laminated plate theory, makes a preliminary judgment on the main load-bearing path and stress distribution characteristics. For example, for a cylindrical section with an axisymmetric structure, under uniform internal pressure p, its circumferential stress σ can be estimated. θ and axial stress σ z as follows:

[0014]

[0015] In the formula, r is the inner radius and t is the wall thickness of the cylinder. When the equipment is a composite laminate structure, the classical laminate theory (CLT) is further adopted to calculate the local principal stress, shear stress, and interlaminar interface stress distribution based on the interlaminar stiffness matrix [Q] and angle transformation matrix [T]. On this basis, a three-dimensional finite element model is established, and the layup parameters of the multilayer composite material (including fiber direction angle, layer thickness, and material anisotropic modulus) are input. Typical boundary conditions (such as internal pressure, end load, and thermal gradient) are applied to simulate and solve the stress-strain response of the structure under service conditions. Key physical quantities are extracted from the simulation output, including principal stress, principal strain, shear stress, thickness strain, thermal stress, and equivalent stress. The equivalent stress is calculated using the Von Mise formula to identify the comprehensive failure region.

[0016] Table 1 shows the fiber optic deployment strategy. Starting from the monitoring function, this invention proposes a fiber optic sensor deployment strategy system based on monitoring characteristics, taking into account the mechanical and thermal anomalies that are prone to occur in composite material pressure-bearing equipment during service. This method has wide adaptability, does not depend on a specific structural shape, and is suitable for health monitoring and fault early warning of various pressure-bearing equipment under complex operating conditions such as high pressure, low temperature, and alternating loads.

[0017] Table 1 Fiber Optic Deployment Strategy

[0018]

[0019]

[0020] Secondly, the fiber types in step S1 include, but are not limited to: distributed fiber optic sensors (OFDR, Brillouin), fiber Bragg grating (FBG) sensors, and temperature-sensitive fibers (Raman or decoupled FBG), suitable for real-time monitoring of strain, temperature, or pressure. Fiber Bragg grating (FBG) sensors measure strain or temperature based on changes in reflected wavelength, suitable for point-based high-precision monitoring; Rayleigh scattering OFDR fibers, based on the principle of frequency domain interference, possess sub-millimeter spatial resolution, enabling continuous distributed strain or temperature measurement; Brillouin fiber sensors achieve long-distance, dual-parameter (strain / temperature) synchronous monitoring by measuring the Brillouin frequency shift response; Raman fiber sensors, based on temperature-sensitive backscattering, can achieve independent, high-precision monitoring of temperature field distribution.

[0021] This invention selects fiber optic types with corresponding sensing capabilities based on the physical characteristics of different monitoring targets to achieve multi-dimensional state sensing of composite pressure-bearing structures. For continuous distribution of principal strain along the path, distributed optical fibers (such as OFDR and Brillouin) are preferably used to achieve continuous monitoring throughout the entire process. For areas sensitive to stress abrupt changes and local damage, a point-based FBG array is used, providing high sensitivity and positioning accuracy. For areas at risk of shear strain and interlaminar debonding, obliquely embedded optical fibers are used to enhance the response to shear slip. In temperature-stress coupling areas, a combination of FBG and temperature-sensitive optical fibers (such as Raman and Brillouin) is used to decouple multi-physics signals. The fiber optic types are not limited to FBG, Brillouin, and OFDR examples; other fiber optic sensors with strain or temperature sensing capabilities can also be selected, and the specific type can be flexibly replaced according to monitoring requirements.

[0022] In step S2, during the composite material winding process, an embedded guide rail or a wire feeder is used to synchronously embed the optical fiber into the predetermined winding layer, maintaining stable optical fiber tension and co-laying the composite material filament bundle to form a stable layout.

[0023] In step S2, the guide rail is a detachable flexible guide rail or a magnetically attached channel structure, possessing high positioning accuracy and suitable for auxiliary deployment in oblique laying paths. The embedded guide rail is made of high-temperature resistant, low-friction coefficient material and is pre-integrated into the mold or winding core surface of the laminating equipment to form a high-precision fiber optic laying channel. The cross-sectional shape of the rail is specially designed to ensure that the fiber maintains a stable position during laying while avoiding damage to the fiber due to excessive compression.

[0024] Secondly, the device in step S2 has a tension control function, and the optical fiber and the fiber bundle are laid together to avoid breakage and micro-bending. During the composite material lamination process, as the fiber and resin are laid layer by layer, the tooling structure such as the intelligent wire feeder simultaneously embeds the optical fiber into the material along the guide track, achieving seamless integration with the process; in the winding process, the wire feeder automatically adjusts the wire feed speed and direction of the optical fiber according to the changes in the winding path to ensure a tight fit between the optical fiber and the composite material.

[0025] In step (3), the flexible interface material is selected from polyimide coating, silicone rubber, or aerogel buffer layer, and the coupling layer material is selected from modified epoxy resin or acrylate elastomer, with the thickness controlled between 50μm and 200μm. A low-temperature flexible coating adhesive or buffer layer is used to protect the optical fiber, preventing damage caused by winding tension and temperature changes. An elastic coupling layer is set between the optical fiber and the substrate to improve sensing coupling efficiency and bonding stability. The elastic coupling layer can efficiently transfer the stress of the composite matrix to the optical fiber. During manufacturing, the optimal bonding effect can be achieved by controlling the thickness of the elastic coupling layer and the curing process parameters.

[0026] The multi-layer sealing structure in step (4) includes: a metal sealing ring, an elastic sealing gasket, a flexible corrugated tube protective structure, and a corrosion-resistant epoxy protective coating. First, a metal sealing ring is set at the fiber outlet to fit tightly with the fiber interface, forming a preliminary airtight barrier using a threaded or crimped structure; a polytetrafluoroethylene or nitrile rubber sealing ring is added in the middle to compensate for micro-gaps and absorb dimensional changes caused by thermal expansion and contraction; a flexible corrugated tube or soft connector is used to cover the fiber outlet section externally, allowing it to undergo micro-displacement under temperature difference and vibration conditions without affecting the stability of fiber transmission; finally, an epoxy protective coating is applied externally to form an overall protective coating, preventing environmental moisture and corrosive gases from entering the sealed cavity and extending the system life.

[0027] The demodulation system in step (5) supports fiber Bragg grating (FBG) wavelength demodulation, Rayleigh scattering-based OFDR demodulation, Brillouin frequency shift demodulation, and Raman scattering demodulation. It features multi-channel input and temperature-strain decoupling processing capabilities, making it suitable for composite demodulation and data fusion of various types of fiber optic sensors. The system uses a main control module to normalize, extract features, and perform fusion algorithm calculations on different types of sensor signals to generate a two-dimensional temperature-strain distribution map.

[0028] Secondly, in step (5), the monitoring system constructs a two-dimensional temperature-strain distribution map and tracks and predicts local anomaly trends through a data model, outputting remote alarm signals and emergency handling suggestions. The fusion algorithm includes wavelet transform, principal component analysis (PCA), and support vector machine (SVM) methods to identify abrupt change features, trend features, and stress state patterns in the signal; the demodulation module can perform temperature-stress decoupling, anomaly point tracking, and trend evolution analysis to realize multi-dimensional state perception and early warning prompts for composite material pressure vessels during service.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] This invention is applicable to the monitoring of complex operating conditions of various composite material pressure-bearing equipment, such as cryogenic high-pressure hydrogen storage cylinders, carbon fiber Type V cylinders, and composite material pressure pipelines. By simultaneously deploying sensing optical fibers during the winding process, problems such as weak bonding, signal attenuation, and sensor detachment are effectively avoided. A multi-layered composite interface structure of bonding, flexible protection, and elastic coupling is formed between the optical fiber sensor and the composite material layer, improving the stability and lifespan of the optical fiber under stress and temperature shocks. The overall process only requires adding a few additional devices and control programs to the original winding yarn, resulting in low modification costs and high integration for existing equipment. In addition, it has distributed, long-cycle, and online monitoring capabilities, enabling the identification of localized equipment damage, leakage risks, and abnormal loads, thereby improving equipment safety. Attached Figure Description

[0031] Figure 1 Flowchart of fiber optic implantation in composite material pressure-bearing equipment;

[0032] Figure 260L Type III hydrogen storage cylinder cross-sectional view;

[0033] Figure 3 Stress-strain analysis of the gas cylinder body;

[0034] Figure 4 Schematic diagram of fiber optic cable deployment;

[0035] Figure 5 Schematic diagram of embedded guide rail structure;

[0036] Figure 6 Block diagram of tension control principle of intelligent wire feeder;

[0037] Figure 7 Flowchart of synchronous fiber optic and fiber bundle laying;

[0038] Figure 8 Schematic diagram of fiber optic cable lead-out and encapsulation;

[0039] Figure 9 Block diagram of the working principle of the hydrogen storage cylinder detection system. Detailed Implementation

[0040] Example 1

[0041] like Figure 1 , Figure 2 and Figure 4 As shown, this embodiment discloses a fiber optic implantation monitoring method and device for composite material pressure-bearing equipment. Taking a type III hydrogen storage cylinder as an example, the method includes the following steps:

[0042] S1. Through theoretical calculations, the structural characteristics and stress distribution of a 60L type III hydrogen storage cylinder are calculated to determine the principal stress concentration area and potential failure area, so as to plan the optical fiber implantation path. The path is laid out along the principal stress direction to cover the key monitoring area.

[0043] like Figure 2 As shown, the gas cylinder uses a 6061 aluminum alloy inner liner, and the composite material is T700 carbon fiber and epoxy resin with added polyethylene glycol. The layered structure is [90°7 / ±5°]. 16 / 90° 11 This forms a typical three-segment structure of "ring-longitudinal-ring", which effectively resists circumferential stress and axial stress, and 2-3 layers of circumferential glass fiber are superimposed on the outermost layer.

[0044] like Figure 3 As shown, stress-strain analysis indicates that the circumferential stress σ in the cylindrical section... θThe main load-bearing direction is concentrated in the 90° section; the thickness compressive strain ε3 shows a sudden gradient change at the interface between the middle and outer layers; τ6 is the interlayer shear stress on the 2nd and 3rd planes, which fluctuates locally in the ±5° composite zone and is a potential debonding zone; the main tensile strain ε1 increases gradually overall but fluctuates between layers. The connection between the end cap and the cylinder forms an axial disturbance concentration area due to the geometric change, while the transition area at the bottle neck is a high-risk area for heat leakage and end stress superposition.

[0045] Based on the above structural characteristics and stress distribution patterns, this invention plans targeted fiber optic deployment paths, as detailed in Table 2. The table clearly defines the fiber optic types and deployment methods matched to different monitoring targets to cover key structural areas and achieve multi-physics state monitoring.

[0046] Table 260L Type III Hydrogen Storage Cylinder Fiber Optic Deployment Strategy

[0047]

[0048] like Figure 4 As shown, to match the different functional areas of the composite material hydrogen storage cylinder structure, this invention selects different types of fiber optic sensors based on the stress characteristics and sensing requirements of each area:

[0049] Because the cylindrical section is under low temperature and high pressure conditions for a long time, its radial thermal gradient and circumferential principal stress are coupled. The present invention deploys distributed optical fibers in this area, which can be used for principal strain monitoring and is also suitable for temperature compensation and thermal coupling characteristic analysis. The distributed optical fiber sensor (such as OFDR) has high spatial resolution and can realize continuous monitoring of the principal stress path along the axial direction.

[0050] In regions with high strain gradients, such as abrupt changes in structural thickness, boundary disturbances, or load redistribution, this invention employs a fiber Bragg grating (FBG) array for point-based deployment. FBGs offer fast response and strong anti-interference capabilities, making them suitable for monitoring localized anomalous changes such as abrupt strain changes and crack initiation.

[0051] In the head transition zone and areas prone to interlaminar shear, an obliquely embedded fiber optic deployment method is used to achieve early warning monitoring of shear slip trends and interlaminar failure. The fiber optics traverse the interlaminar interface at an angle of ±θ° to improve the response sensitivity to shear strain.

[0052] The connection area between the head and the cylinder forms a stress and deformation coupling concentration area due to abrupt changes in curvature and thickness, which is prone to axial disturbance and local failure. This invention uses an FBG array deployed in the transition layer to capture complex coupled strain changes.

[0053] The transition zone at the bottle neck is a critical monitoring location due to factors such as the presence of metal joints, abrupt changes in the material's elastic modulus, and sensitivity to thermal leakage. This invention employs a combined deployment of FBG sensors and Brillouin or Raman temperature optical fibers to achieve joint monitoring of local thermal expansion, mechanical stress, and leakage risk.

[0054] S2. During the composite material winding process, the optical fiber is synchronously embedded into the predetermined winding layer by using tooling structures such as embedded guide rails or high-precision intelligent wire release devices to maintain stable optical fiber tension, avoid micro-bending or breakage, and form a stable layout in conjunction with the composite material filament bundle.

[0055] Figure 5 The diagram shows the structure of the embedded guide rail. The embedded guide rail mainly consists of a fixing block 1, a fixing block 2, a movable block, a channel, and an adhesive layer. Fixing block 1 is located at one end of the rail and is used to anchor the guide rail. Its fixing method can be a mechanical clamp, magnetic block, or vacuum suction cup to ensure the rail is stably positioned on the surface of the winding mold. Fixing block 2 is located in the middle of the rail, providing auxiliary support and preventing the rail from tilting. It works in conjunction with the adhesive layer to fix the rail, thereby improving overall stability. The adhesive layer is placed between the guide rail and the surface of the composite material mold. It can be made of high-temperature double-sided adhesive, hot melt adhesive tape, or a thin layer of self-adhesive resin. It can also be used in combination with magnetic or vacuum adsorption methods to temporarily fix the uncured winding layer surface. The channel is the fiber optic guiding path. Its central turning section is designed with a minimum bending radius limit to ensure that the fiber optic cable will not break or suffer micro-bending loss due to sharp bends when changing direction, thus ensuring signal transmission quality. Fiber optic paths 1 and 2 illustrate different guiding directions of the fiber optic cable within the guide rail. The movable block is located at the track entrance end and can be finely adjusted at the angle according to the requirements of the winding process to ensure that the optical fiber enters the track smoothly and remains stable. The optical fiber enters from the movable block at the right end, is guided along the channel, and after passing through the turning section, is embedded into the uncured composite material layer from the exit end, and finally achieves synchronous laying with the fiber bundle.

[0056] Figure 6 The diagram shows the block diagram of the tension control principle of the intelligent wire feeding device. The optical fiber is fed from the wire feeding reel and enters the winding system after being detected by a tension sensor. A swing arm with an elastic mechanism is positioned in the fiber path to absorb speed fluctuations, stabilize tension, and use position changes as one of the feedback signals. The controller receives the displacement signals from the tension sensor and the swing arm, calculates the deviation between the current tension and the set value in real time, and drives the motor to adjust the reel speed and torque, thereby achieving closed-loop tension control. This system can ensure that the fiber tension is stable within the set range (e.g., 0.1-0.3N), avoiding fiber breakage due to excessive tension or micro-bending due to insufficient tension.

[0057] When laying optical fibers, avoid placing them at the bottom or outermost layer. The bottom layer experiences the highest stress and is tightly wound, making it prone to fiber breakage. The outermost layer is greatly affected by the environment and can easily interfere with signals. In oblique laying, to avoid being cut, the fiber angle should be consistent with the winding angle, away from the extreme region of principal shear stress, and laid in the shallow to middle layer for the safest approach.

[0058] Figure 7 This is a flowchart illustrating the synchronous laying process of optical fibers and fiber bundles using a guide rail. An independent, controllable tension optical fiber laying module is added to the existing winding equipment, equipped with a tension control and deviation correction system, enabling precise fiber laying. When embedding fibers at an angle, a guide rail is best used to prevent fiber breakage and maintain the stability and accuracy of the laying path. This method is suitable for situations requiring high precision in fiber positioning during wet winding, where the fiber needs to be embedded in a specific layer. First, a section of the bottom composite material layer is wound, and the winding machine is moved to the predetermined fiber embedding position. Fiber winding is stopped, and the winding head is retracted or positioned and fixed, ensuring that the surface adhesive layer has not cured during this process. The guide rail (flexible groove or forming groove) is manually attached or clamped using a mechanical clamping device. A layer of flexible interface material is evenly laid in the guide rail groove to form an elastic coupling layer with the composite matrix. Temporary magnetic suction or vacuum chucks can be used to fix it to the winding surface. The intelligent fiber laying device and other tooling structures are activated to embed the fiber along the guide rail path, with the fiber tension controlled at 0.1-0.3N. After the fiber is placed, local adhesive is applied for reinforcement. After removing the temporary guide rail, start the winding machine and continue winding the upper layer material to place the optical fiber in a stable intermediate layer.

[0059] S3. A flexible interface material and an elastic coupling layer are provided between the optical fiber and the composite material. The coupling layer includes a low-modulus elastomer, a buffer pad, or a modified resin, etc., to improve the bonding strength between the optical fiber and the substrate, the sensing coupling efficiency, and the temperature difference adaptability.

[0060] This invention employs high-strength silica optical fiber as the sensor, whose coefficient of thermal expansion is much smaller than that of the composite matrix. During the low-temperature (20K) cooling process, the interfacial thermal strain difference is approximately 1.67%. The selection of a flexible cladding material (polyimide coating) allows the optical fiber to withstand a thermal strain greater than 2% without thermal shearing. Calculations using the Shear-Lag model show that under high pressure (35MPa) loading, the transmitted shear stress is much smaller than the interfacial strength, preventing peeling or shear failure. Simultaneously, the estimated tensile strain of the optical fiber is 1.4%, significantly higher than the actual structural strain. Theoretically, the optical fiber exhibits good survivability and operational adaptability. In addition to the flexible cladding layer, an elastic coupling layer is placed between the optical fiber and the matrix. The coupling layer material is modified epoxy resin, and the thickness of both is controlled between 50μm and 200μm.

[0061] S4. After winding, a multi-layer sealing structure is set at the bottle mouth, end or optical fiber outlet of the equipment. The structure includes a metal sealing ring, a flexible sealing gasket, a bellows protection structure and a low-temperature resistant outer protective layer, which is used to achieve sealed lead-out of the optical fiber and long-term reliable encapsulation.

[0062] like Figure 8 The diagram shows the fiber optic cable exit and encapsulation. The fiber itself is embedded in a composite material winding layer and laid synchronously with the winding, providing real-time sensing of the principal stress path. The fiber exits through a small orifice at the bottle neck, with the orifice chamfered to prevent sharp edges from damaging the fiber. The exiting fiber undergoes multiple sealing structures, including a metal sealing ring, an elastic sealing gasket, and an O-ring seal (commonly made of materials such as PTFE or NBR), to achieve good initial airtightness and accommodate dimensional changes caused by thermal expansion and contraction. To reduce the impact of environmental disturbances, the exiting section is encased in a flexible corrugated tube or a soft connection structure to effectively buffer the transmission of mechanical stress. A standard fiber optic interface (such as an FC / APC or LC / APC plug) is installed on the outermost side to achieve a reliable connection with the demodulation system. Simultaneously, the entire exit and connection area is coated with a low-temperature resistant epoxy protective coating to prevent the intrusion of moisture and corrosive gases, improving the overall reliability and lifespan of the system.

[0063] S5. Based on the fiber optic demodulation system, the signal acquired by the embedded fiber optic cable is analyzed in real time to obtain the temperature field and strain field distribution of the equipment under complex load or temperature environment, identify potential damage and heat leakage risks, form a health status assessment result, and combine with the alarm mechanism to realize intelligent early warning of structural anomalies.

[0064] like Figure 9 The diagram shows the working principle block diagram of the hydrogen storage cylinder detection system. The demodulator converts the optical signal transmitted from the optical fiber into an electrical signal and performs preliminary processing. Distributed fiber optic sensing (OFDR) obtains a continuously distributed principal strain field based on the Rayleigh scattering characteristics in the optical fiber. FBG (Fiber Optic Gauge) forms periodic refractive index modulation in the optical fiber, reflecting specific wavelengths. Several FBG sensing points are embedded in high strain gradient regions and areas with drastic thickness changes. The demodulation system reads the wavelength changes in real time and converts them into strain values. After demodulation, the temperature-strain composite FBG fiber is mathematically decoupled to obtain independent values ​​for temperature drift and strain drift. The system uses a main control module to normalize, extract features, and perform fusion algorithm calculations on different types of sensor signals to generate a two-dimensional temperature-strain distribution map. The fusion algorithm includes wavelet transform, principal component analysis (PCA), and support vector machine (SVM) methods to identify abrupt changes, trend characteristics, and stress state patterns in the signal. The demodulation module can perform temperature-stress decoupling, anomaly tracking, and trend evolution analysis to achieve multi-dimensional state perception and early warning of composite pressure vessels during service.

[0065] Example 2

[0066] This embodiment provides a fiber optic implantation monitoring device for composite material pressure-bearing equipment, and uses the method in Embodiment 1 for monitoring, specifically including:

[0067] Data acquisition module: used to acquire the three-dimensional structural features, material performance parameters and operating condition data of composite material pressure equipment, and input the data into the data processing module;

[0068] Data processing module: Analyzes the stress distribution of composite material pressure-bearing equipment through theoretical calculations and / or finite element simulations, determines the principal stress concentration area and potential failure area, and generates fiber optic implantation paths;

[0069] Fiber optic implantation assembly: used to synchronously embed optical fibers into the winding layers during the composite material winding process using a guiding device; an elastic coupling layer is formed between the fiber and the composite matrix through a flexible interface material; after winding, a multi-layer sealing structure is set for fiber extraction and protection;

[0070] Signal acquisition module: used to acquire strain and temperature signals from fiber optic sensors embedded in composite materials;

[0071] Fiber optic demodulation system: used to demodulate the acquired fiber optic signals;

[0072] Status assessment module: Used to perform real-time equipment health status assessment based on multi-dimensional data from fiber optic sensors, and trigger alarm feedback when thresholds are exceeded.

[0073] In this embodiment, the method in Example 1 is used to implant optical fibers into the three types of hydrogen storage cylinders and to collect signals from the embedded optical fibers. Based on the optical fiber demodulation system, the signals collected by the embedded optical fibers are analyzed in real time to obtain the temperature field and strain field distribution of the equipment under complex load or temperature environment, identify potential damage and heat leakage risks, form a health status assessment result, and combine with the alarm mechanism to realize intelligent early warning of structural anomalies.

[0074] Specifically, the potential damage that the fiber optic monitoring system can identify includes: interlayer debonding, fiber breakage, matrix cracking, and interface fatigue and fiber slippage. Under the above damage conditions, the monitoring signal exhibits characteristics such as sudden changes in local strain, discontinuous shifts, signal steps, or unstable time-series responses.

[0075] The thermal environment-related risks that the fiber optic monitoring system can identify mainly include: low-temperature thermal stress damage, heat leakage risk in the bottle or valve opening area, and insulation layer damage or thermal management failure. Under the above risk conditions, the monitoring signal will show characteristics such as abnormal shift of strain with temperature change, abnormal increase of local temperature accompanied by strain drift, or cold spots and overheated areas in the temperature field distribution.

[0076] Comprehensive analysis results show that this system can output a two-dimensional temperature-strain distribution map and locate abnormal areas. It generates health status assessment results based on damage type and risk level, including "normal operation", "early warning status" and "alarm status". When the system detects risks such as local debonding, fiber breakage, matrix cracking or heat leakage exceeding the set threshold, it will automatically trigger an alarm and indicate the abnormal location, thereby realizing intelligent health monitoring and structural anomaly early warning for three types of hydrogen storage cylinders.

[0077] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method of optical fiber implant monitoring for composite pressure equipment, characterized by, The specific steps include the following: S1. Determine the fiber optic implantation path based on the structural and stress distribution characteristics of composite material pressure-bearing equipment; Step S1 calculates the structural characteristics and stress distribution of composite material pressure-bearing equipment through theoretical calculation and / or finite element simulation, and determines the principal stress concentration area and potential failure area. Fiber optic implantation paths are planned based on principal stress concentration areas and potential failure areas. The fiber optic implantation path is laid along the principal stress direction, covering the monitoring area; Fiber optic types include one or more of distributed fiber optic sensors, fiber Bragg grating sensors, and temperature-sensitive fibers; S2. During the composite material winding process, the optical fiber is synchronously embedded into the winding layer using a guiding device; In step S2, during the composite material winding process, an embedded guide rail or a wire feeder is used to synchronously embed the optical fiber into the predetermined winding layer, maintaining stable optical fiber tension and co-laying with the composite material filament bundle to form a stable layout. The guide rail is a detachable flexible guide rail or a magnetic channel structure, which is suitable for auxiliary layout of inclined laying paths; The cable laying device has a tension control function, which is used for the coordinated laying of optical fibers and fiber bundles to avoid breakage and micro-bending; S3. An elastic coupling layer is formed between the flexible interface material and the composite matrix; S4. After winding, a multi-layer sealing structure is set for optical fiber lead-out. S5. Based on the fiber optic demodulation system, temperature and strain monitoring is performed on composite material pressure-bearing equipment to achieve real-time perception, diagnosis and early warning of equipment health status.

2. A method for optical fiber implant monitoring of composite pressure equipment according to claim 1, characterized in that, In step S1, the fiber optic path selects the matching fiber type and layout method according to the physical field characteristics that the equipment needs to monitor. Its layout strategy is determined based on characteristic parameters such as principal stress direction, high strain gradient region, shear failure risk region, and significant thermal-stress coupling region.

3. A method for optical fiber implant monitoring of composite pressure equipment according to claim 1, characterized in that, Step S3 involves setting a flexible interface material and an elastic coupling layer between the optical fiber and the composite material. The coupling layer includes a low-modulus elastomer, a buffer pad, or a modified resin, which is used to improve the bonding strength between the optical fiber and the substrate, the sensing coupling efficiency, and the temperature difference adaptability. In step S3, the flexible interface material is selected from polyimide coating, silicone rubber or aerogel buffer layer, and the coupling layer material is selected from modified epoxy resin or acrylate elastomer, with the thickness controlled between 50μm and 200μm.

4. The method of claim 1, wherein, Step S4: After winding is completed, a multi-layer sealing structure is set at the bottle opening, end, or fiber optic outlet of the equipment. The sealing structure includes a metal sealing ring, a flexible sealing gasket, a corrugated tube protection structure, a low-temperature resistant outer protective layer, and a corrosion-resistant epoxy protective coating, which are used to achieve sealed lead-out of the optical fiber and long-term reliable encapsulation.

5. The fiber optic implantation monitoring method for composite material pressure-bearing equipment according to claim 1, characterized in that, Step S5 involves real-time analysis of the signals acquired by the embedded optical fiber based on the optical fiber demodulation system, obtaining the temperature and strain field distribution of the equipment under complex loads or temperature environments, identifying potential damage and heat leakage risks, forming a health status assessment result, and combining it with an alarm mechanism to achieve intelligent early warning of structural anomalies.

6. A method for optical fiber embedded monitoring of composite pressure equipment according to claim 1 or 5, characterized in that, The demodulation system in step S5 supports fiber Bragg grating wavelength demodulation, OFDR demodulation based on Rayleigh scattering, Brillouin frequency shift demodulation, and Raman scattering demodulation. It is used for multi-channel input and temperature-strain decoupling processing, as well as composite demodulation and data fusion of various types of fiber optic sensors.

7. An optical fiber implant monitoring device for composite pressure equipment, monitored using the method according to any one of claims 1-6, characterized in that, include: Data acquisition module: used to acquire the three-dimensional structural features, material performance parameters and operating condition data of composite material pressure equipment, and input the data into the data processing module; Data processing module: Analyzes the stress distribution of composite material pressure-bearing equipment through theoretical calculations and / or finite element simulations, determines the principal stress concentration area and potential failure area, and generates fiber optic implantation paths; Fiber optic implantation assembly: used to synchronously embed optical fibers into the winding layers during the composite material winding process using a guiding device; An elastic coupling layer is formed between a flexible interface material and the composite matrix; After winding, a multi-layer sealing structure is set for fiber optic lead-out and protection; Signal acquisition module: used to acquire strain and temperature signals from fiber optic sensors embedded in composite materials; Fiber optic demodulation system: used to demodulate the acquired fiber optic signals; Status assessment module: Used to perform real-time equipment health status assessment based on multi-dimensional data from fiber optic sensors, and trigger alarm feedback when thresholds are exceeded.

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