A self-sensing flange gasket for structural health monitoring of pipeline systems.

Abstract

This invention discloses a self-sensing flange gasket for structural health monitoring of pipeline systems. The flange gasket consists of functional components and signal transmission circuit components. The functional components have a three-layer concentric ring contact structure, including a sealing inner ring layer, a leakage detection middle ring layer, and a sealing reinforcement outer ring layer, used to achieve the sealing and condition monitoring functions of the flange gasket. The signal transmission circuit components include an inner ring edge electrode layer and a middle ring planar interdigitated electrode layer, used to acquire and transmit electrical signals from the flange gasket. All components use flexible PDMS as the base material to ensure the elastic deformation sealing capability of the flange gasket, while the self-adhesive properties of PDMS are used to achieve seamless assembly between the layers. This invention, through a multi-functional layer modular design, utilizes multi-dimensional electrical signal changes caused by different physical parameters to achieve simultaneous detection of fastening pressure and leakage components, thus meeting the engineering requirements for condition monitoring of pipeline systems.

Description

Technical Field

[0001] This invention relates to the field of structural health monitoring of pipeline systems, and more specifically to a self-sensing flange gasket for structural health monitoring of pipeline systems. Background Technology

[0002] Pipeline systems play a vital role in oil and gas energy supply, water supply and drainage network deployment, and the construction of gas and heat systems. However, due to the long construction periods and wide coverage areas of pipelines, the immense operating pressures of these systems, the corrosive effects of the transported media, and external environmental disturbances, structural health problems frequently occur. Besides leading to leaks of the transported media, structural health issues in pipeline systems can also result in serious accidents such as fires, explosions, and poisoning.

[0003] Currently, there are various methods for inspecting pipeline structural health. One method is manual leak detection, but this relies heavily on the experience of the inspectors and is easily affected by environmental noise, often resulting in a significant leak by the time it is detected. Other methods include ground-penetrating radar, ultrasonic testing, vibration detection, and visual robots. However, these methods have three major limitations: 1) Some methods can only address significant structural problems such as leaks, blockages, or deformations in the pipeline, resulting in insufficient coverage and continued significant socio-economic losses; 2) Some methods require deep penetration into the pipeline, making it impossible to perform inspections while the pipeline is in operation, which disrupts normal pipeline system operation and increases inspection costs; 3) Some methods lack long-term online monitoring capabilities, making it difficult to monitor the pipeline's structural health in real time, and posing significant challenges in determining the extent and location of pipeline defects.

[0004] Self-sensing methods based on smart materials utilize the electrical properties of structural components in response to external environmental stimuli. They can detect parameters such as temperature, humidity, pressure, and deformation without the need for external sensing elements, and have attracted significant research attention in fields such as architecture, bridges, transportation, and aerospace. Therefore, applying this method to pipeline networks may provide a feasible solution for monitoring the structural health of large-scale pipeline systems in practical applications.

[0005] According to statistics on the locations of pipeline network system failures, the failure rate at pipeline interface locations (including valves, joints, tees, etc.) is as high as 80%. This is because stress distribution is concentrated at interface locations, making them weak points in the pipeline system's structure. However, currently, there is a lack of effective detection methods for the types and severity of interface failures. In interface failure detection schemes, pressure and leakage components are the two most critical physical variables. When the interface becomes loose or cracked, the pipe body deforms, or soil settlement occurs, the pressure distribution at the interface will change, causing the pressure distribution at the location of the anomaly to differ from other parts. Direct leakage detection of the transported medium is the most intuitive way to determine whether a leak has occurred in the pipeline. Therefore, if the pressure distribution at the interface and the leakage of the transported medium can be directly obtained, the type of failure at the current connection point can be effectively analyzed and its severity assessed. Combined with a large-scale distributed monitoring network, it is hoped that rapid structural health monitoring of the pipeline system can be achieved.

[0006] Currently, structural health monitoring of pipeline networks based on self-sensing methods is still in its early stages of development, with limited related research. Therefore, this invention aims to design a self-sensing flange gasket that can simultaneously monitor the distribution of fastening pressure and leakage components at flange connections, which are key pressure-bearing and prone to leakage. This will enable real-time and accurate condition monitoring and fault diagnosis of the pipeline system, providing a feasible solution for structural health monitoring of pipeline networks. Summary of the Invention

[0007] The purpose of this invention is to propose a self-sensing flange gasket with multimodal sensing function to realize real-time structural health monitoring of pipeline systems.

[0008] The present invention provides a self-sensing flange gasket for structural health monitoring of a pipeline system, comprising three concentrically arranged annular components, wherein the three components, from the inside out, are an inner ring layer, a middle ring layer, and a sealing and reinforcing outer ring layer;

[0009] The inner ring layer includes an inner ring edge electrode layer and a sealing inner ring layer. The sealing inner ring layer is used for sealing and protecting the conveying pipeline and detecting its own fastening pressure. The diameter of the inner ring edge electrode layer is equal to the diameter of the sealing inner ring layer (the inner diameter of the inner ring edge electrode layer is equal to the inner diameter of the sealing inner ring layer, and the outer diameter of the inner ring edge electrode layer is equal to the outer diameter of the sealing inner ring layer). Multiple contact electrodes for detecting the resistance change of the sealing inner ring layer are uniformly arranged circumferentially. The exposed side of the contact electrode of the inner ring edge electrode layer is in contact with the sealing inner ring layer. Each contact electrode is connected to a metal signal line for transmitting the resistance information detected by the contact electrode.

[0010] The intermediate ring layer includes a leak detection intermediate ring layer and an intermediate ring planar interdigitated electrode layer. The leak detection intermediate ring layer is used to detect leaks. The diameter of the intermediate ring planar interdigitated electrode layer is equal to the diameter of the leak detection intermediate ring layer (the inner diameter of the intermediate ring planar interdigitated electrode layer is equal to the inner diameter of the leak detection intermediate ring layer, and the outer diameter of the intermediate ring planar interdigitated electrode layer is equal to the outer diameter of the leak detection intermediate ring layer). Multiple interdigitated electrodes are uniformly arranged circumferentially. When the pipeline leaks, the leaked material contacts the leak detection intermediate ring layer and causes a change in its capacitance. The exposed side of the interdigitated electrode of the intermediate ring planar interdigitated electrode layer contacts and connects to the leak detection intermediate ring layer. Each interdigitated electrode is connected to two metal signal lines for transmitting the capacitance information detected by the interdigitated electrode.

[0011] The sealing and reinforcing outer ring layer serves as a double seal for the conveying pipeline;

[0012] The inner ring edge electrode layer and the middle ring planar interdigitated electrode layer are respectively disposed on the left and right sides of the flange gasket, and the number of contact electrodes and interdigitated electrodes is greater than or equal to 8.

[0013] Furthermore, the height of the inner ring layer is equal to the height of the sealing and reinforcing outer ring layer to ensure dual sealing performance; the height of the middle ring layer is less than or equal to that of the sealing and reinforcing outer ring layer to ensure that it will not experience large electrical signal fluctuations under tightening pressure, thus affecting multimodal detection capabilities.

[0014] The present invention also provides a method for preparing the self-sensing flange gasket for structural health monitoring of a pipeline system, comprising the following steps:

[0015] Step 1): Design and obtain five different sizes of circular molds;

[0016] Step 2): Mix the silane prepolymer with toluene to obtain mixture I, and simultaneously mix the CB particles with toluene to obtain mixture II; mix mixture I and mixture II uniformly and heat until the toluene is completely evaporated, then add a crosslinking agent dropwise to obtain a viscous, stable conductive composite material CB / PDMS;

[0017] Step 3): Pour the viscous, stable conductive composite material CB / PDMS into the molds of the sealing inner ring layer and the sealing and reinforcing outer ring layer, respectively. Remove internal air bubbles, heat to cure, cool, and demold to obtain the sealing inner ring layer and the sealing and reinforcing outer ring layer with piezoresistive properties.

[0018] Step 4): Pour the uniformly mixed granulated sugar and erythritol powder into the mold of the leak detection intermediate ring layer, and heat to make the erythritol and granulated sugar particles adhere to form a sugar cake; then pour the PDMS / toluene solution into the mold of the leak detection intermediate ring layer to completely fill the gaps inside the sugar cake, remove internal air bubbles, and heat to solidify, obtaining a PDMS-filled sugar cake; then immerse the PDMS-filled sugar cake in deionized water and heat to obtain porous PDMS; demold the porous PDMS, wash and dry it, and coat the surface of the porous PDMS with a nano-film material sensitive to the pipeline transport medium, then rinse with deionized water and dry to obtain the leak detection intermediate ring layer; wherein, the mass ratio of silane prepolymer: crosslinking agent: toluene in the PDMS / toluene solution is 10:1:15~30;

[0019] Step 5): Pour the uniformly mixed liquid PDMS into the mold of the inner ring edge electrode layer, remove internal air bubbles, heat to solidify, cool, and demold to obtain a flexible substrate of the inner ring edge electrode layer; attach several circumferentially uniformly distributed contact electrodes to the upper surface of the flexible substrate; encapsulate several metal signal lines with the contact electrodes respectively through conductive silver paste, with the leads extending radially outward along the ring; then coat the surface of the flexible substrate with the attached contact electrodes with a layer of the viscous stable conductive composite material CB / PDMS, and use the self-adhesive properties between the liquid and solid phases of PDMS to achieve seamless and stable assembly between the inner ring edge electrode layer and the sealed inner ring layer;

[0020] Step 6): Design a photolithographic pattern for a planar interdigitated microchannel structure and process it into a film. After pre-baking, soft baking, exposure, post-baking, washing, and hard baking, a photolithographic mold with multiple planar interdigitated patterns is obtained. The planar interdigitated patterns on the photolithographic mold are divided to obtain multiple small photolithographic molds with the same planar interdigitated pattern. These small photolithographic molds are evenly distributed circumferentially at the bottom of the mold with the intermediate ring interdigitated electrode layer. Then, a uniformly mixed liquid PDMS is poured into the mold, internal air bubbles are removed, and the mixture is heated to solidify, cooled, and demolded to obtain a flexible substrate with an embedded intermediate ring planar interdigitated electrode layer within the microchannel structure. The substrate is coated with a viscous, stable conductive composite material CB / PDMS into the microchannel structure of the flexible substrate to form a planar interdigitated electrode layer with an intermediate ring. Two metal signal lines are penetrated through the flexible substrate and contacted with an interdigitated electrode in the microchannel structure. The liquid PDMS is used to encapsulate the penetration points on the flexible substrate, and the leads are radially outward along the ring to encapsulate the metal signal lines for each interdigitated electrode. A layer of the composite material CB / PDMS liquid phase film obtained in step 2) is uniformly spin-coated on one side with the planar interdigitated pattern, so that the intermediate ring interdigitated electrode layer and the leakage detection intermediate ring layer can achieve self-adhesive and stable assembly.

[0021] Step 7): Apply a layer of liquid PDMS evenly to the inner sealing ring layer, the leak detection intermediate ring layer, and the sealing reinforcement outer ring layer, and assemble them together to form a concentric ring contact structure. Then heat and cure to form the final self-sensing flange gasket. At this time, the inner ring edge electrode layer and the intermediate ring planar interdigitated electrode layer are located on opposite sides of the self-sensing flange gasket.

[0022] Further, in step 2), the mass ratio of silane prepolymer to toluene is 1:1 to 2, the mass ratio of CB particles to toluene is 1:10 to 20, and the mass ratio of silane prepolymer: crosslinking agent: CB particles in the obtained stable conductive composite material is 10:1:1.94 to 3.66; in steps 5) and 6), the mass ratio of silane prepolymer to crosslinking agent in the uniformly mixed liquid phase PDMS is 10:1.

[0023] The present invention further provides a method for structural health monitoring of a pipeline system based on the flange gasket, comprising the following steps:

[0024] Step S1: Install the self-sensing flange gasket at one or more flange connection structures that need to be detected in the pipeline. Each self-sensing flange gasket is equipped with an electrical signal reading module, which is connected to all metal signal lines to read the sensing data of the self-sensing flange gasket. The sensing data includes the resistance information R of the sealing inner ring layer and the capacitance information C of the leakage detection intermediate ring layer. Several self-sensing flange gaskets are grouped into a unit group and a signal transmission station is configured. The sensing data of all self-sensing flange gaskets connected to it are uploaded to the terminal server through the signal transmission station.

[0025] Step S2: When an unknown fault occurs in the pipeline, the sensing data of the self-sensing flange gasket in the fault area will fluctuate significantly. When the abnormal value in the sensing data reaches a certain threshold, an alarm signal will be directly triggered, and the sensing data of the self-sensing flange gasket at the abnormal point corresponding to the abnormal value will be decoded and analyzed on the terminal server.

[0026] Step S3: The decoding analysis involves calculating the actual tightening pressure distribution and leakage component distribution information from the electrical signals in the sensor data of the self-sensing flange gasket. During signal processing, on one hand, the piezoresistive effect of the sealing inner ring layer and electrical impedance tomography are used to obtain the conductivity distribution map caused by the tightening pressure. A conductivity-pressure mapping model is then used to plot the current flange's tightening pressure distribution heat map. On the other hand, when a micro-leak occurs in the pipeline, the porous sensitive structure of the leak detection intermediate ring layer adsorbs the leaked pipeline transport medium. Based on the magnitude and radiation area of ​​the adsorbed leaked substance, the local dielectric distribution changes. The capacitance information detected by the planar interdigital capacitor directly reflects this dielectric constant change, and a dielectric constant-transport medium mapping model is used to plot the current flange's leakage component distribution heat map. Since pressure fluctuations and leakage conditions caused by different faults vary significantly, the current fault manifestation can be determined by combining the tightening pressure distribution heat map and the leakage component distribution heat map.

[0027] Step S4: Combining the heat map of tightening pressure distribution with the heat map of leakage component distribution can further determine the fault type and assess the severity of the fault, which helps to formulate targeted fault handling solutions. Furthermore, based on the time evolution of flange gasket sensor data, flange gasket lifecycle analysis and fault precursor prediction can be achieved. And by using spatial data from multiple sets of flange gaskets in the pipeline system, combined with information from each flange location, a series of potential problems in the pipeline system can be comprehensively assessed, enabling structural health monitoring of the pipeline system.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The materials used in the preparation of this invention are PDMS, CB, and copper wire, which are inexpensive and have stable properties. Furthermore, the preparation process of this invention is mature, the steps are clear, the structure is simple, it supports modular production, has the potential for large-scale production, and has strong engineering application capabilities.

[0030] 2. This invention uses CB / PDMS conductive composite material as the body material for flange gaskets. Its flexibility ensures sealing performance, while its conductivity and piezoresistive characteristics can directly detect the current applied pressure. By adjusting the mixing ratio of CB / PMDS, the pressure sensitivity range and pressure sensitivity can be freely set, which has extremely strong adaptability to pipeline operating conditions.

[0031] 3. This invention improves the adsorption and detection capabilities of leaked substances by coating a porous structure with a specific sensitive film for pipeline transport media, and simplifies the capacitance measurement circuit by using planar interdigitated electrodes; the appropriate sensitive film can be selected according to the material characteristics of the pipeline transport media, and it has extremely strong adaptability to pipeline transport media.

[0032] 4. This invention adopts a three-layer concentric ring contact structure, which significantly improves the sealing performance while physically decoupling the perception of tightening pressure and leakage. The inner and outer rings ensure sufficient response time between detecting flange failure caused by inner ring failure and serious pipe failure caused by outer ring failure. The middle ring is only sensitive to the leaked components under normal operating conditions, eliminating the cross-coupling effect of tightening pressure and leaked substances.

[0033] 5. This invention will present different distribution information in different fault scenarios. Among them, electrical impedance tomography technology can directly generate the current conductivity distribution image through edge electrodes and generate a real-time fastening pressure distribution thermal map through pressure-conductivity response model; by fitting the distribution of planar interdigitated electrode array, the current dielectric constant distribution image can also be generated based on multi-site capacitance information, and a real-time leakage component distribution thermal map can be generated through transport medium-dielectric constant correlation model.

[0034] 6. In practical engineering applications, this invention only requires replacing the original flange gasket accessories without introducing additional equipment, greatly reducing interference to the pipeline network system and lowering the difficulty of implementation. The remote data transmission module enables remote processing of abnormal situations, and combined with intelligent identification and classification algorithms, it can analyze fault types and assess fault severity in real time. Utilizing the spatiotemporal attributes of the flange gasket sensor network, it can also realize flange gasket lifecycle analysis and early warning prediction, as well as comprehensive performance evaluation and overall structural health status monitoring of the pipeline network system. Attached Figure Description

[0035] Figure 1 This is a three-dimensional view of the self-sensing flange gasket described in this invention patent;

[0036] Figure 2 This is an exploded view of a self-sensing flange gasket;

[0037] Figure 3 yes Figure 1 Top view and bottom view;

[0038] Figure 4 This is a flowchart of the data processing process;

[0039] Figure 5 This is a schematic diagram of a leakage test scenario for a delivery pipeline.

[0040] Figure 6 This is a cross-sectional schematic diagram of the flange connection of the conveying pipeline;

[0041] Figure 7 It is a diagram showing the tightening pressure of the flange gasket and the distribution of leakage components in the event of a pipeline leak.

[0042] Figure 8A top-view schematic diagram of a pipeline deformation test scenario;

[0043] Figure 9 It is a diagram showing the fastening pressure and leakage component distribution of the flange gasket sensing network under stress deformation of the pipeline.

[0044] Reference numerals: 1. Inner ring layer; 1-1. Sealing inner ring layer; 2. Middle ring layer; 2-1. Leak detection middle ring layer; 3. Sealing reinforcement outer ring layer; 1-2. Inner ring edge electrode layer; 2-2. Middle ring planar interdigitated electrode layer. Detailed Implementation

[0045] The present invention will be further described and illustrated below with reference to specific embodiments. The following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other.

[0046] This invention proposes a flange gasket with multimodal sensing capabilities. The invention will be further described below with reference to the accompanying drawings and embodiments. The flange gasket with multimodal sensing capabilities provided in this invention is suitable for detecting large-scale fastening pressure distribution and leakage at the interface of a pipeline system, enabling real-time structural health monitoring of the pipeline network system.

[0047] Example 1

[0048] The self-sensing flange gasket of this embodiment consists of three functional ring assemblies and two transmission circuit ring assemblies. It includes a sealing inner ring layer 1-1 (inner diameter 210mm, outer diameter 235mm, height 5mm) for sealing protection and pressure detection; a leak detection intermediate ring layer 2-1 (inner diameter 235mm, outer diameter 255mm, height 4.5mm) for adsorbing leaking substances and detecting leaks; a sealing reinforcement outer ring layer 3 (inner diameter 255mm, outer diameter 280mm, height 5.5mm) with double sealing function; an inner ring edge electrode layer 1-2 (inner diameter 210mm, outer diameter 235mm, height 0.5mm) for monitoring inner ring pressure distribution; and an intermediate ring planar interdigitated electrode layer 2-2 (inner diameter 235mm, outer diameter 255mm, height 1mm) for monitoring intermediate ring leaks. Figure 1As shown. Both the inner sealing ring and the outer sealing reinforcement ring are made of PDMS-based composite material (CB / PDMS) doped with conductive carbon black particles. The leak detection intermediate ring is composed of a porous PDMS foam structure, which utilizes the material's flexibility and elasticity to ensure sealing while using its piezoresistive properties to detect pressure distribution. The porous PDMS foam structure is coated with a nanofilm material sensitive to the transport medium of the pipeline. The inner ring edge electrode layer uses PDMS as a flexible substrate, with several copper foil tapes attached to its surface as contact electrodes. This allows for the detection of the inner ring's conductivity distribution using a multi-electrode arrangement and Electrical Impedance Tomography (EIT) technology, simultaneously reflecting the current pressure distribution. The intermediate ring planar interdigitated electrode layer uses PDMS as a flexible substrate, with a planar interdigitated microchannel structure on the flexible substrate. Interdigitated electrodes are formed by filling the planar interdigitated microchannel structure with CB / PDMS.

[0049] The inner sealing ring layer is flexible and conductive, and will change its conductivity distribution under external pressure.

[0050] The sealing and reinforcing outer ring layer is flexible and will undergo elastic deformation under external pressure to achieve a sealing effect.

[0051] The leak detection intermediate ring layer can adsorb the leaked pipeline transport medium and change its own dielectric constant distribution.

[0052] The inner ring edge electrode layer can obtain the fastening pressure distribution information of the sealing inner ring layer by acquiring the resistance distribution of the sealing inner ring layer.

[0053] The intermediate ring planar interdigitated electrode layer can obtain the leakage component distribution information of the leakage detection intermediate ring layer by acquiring the capacitance distribution of the leakage detection intermediate ring layer.

[0054] Each component is a concentric ring shape, achieving seamless and stable assembly by utilizing the self-adhesive properties between PDMS substrate materials. Its three-dimensional exploded view is shown below. Figure 2 As shown. Figure 3The top and bottom views of the self-sensing flange gasket are shown, intuitively demonstrating the specific form of its concentric ring contact structure. When axial pressure is applied to the self-sensing flange gasket, due to the flexibility of the PDMS substrate material, the entire flange gasket undergoes elastic deformation. Due to the piezoresistive characteristics of the material used in the inner sealing ring layer 1-1, the surface pressure-induced material strain effect directly affects its conductivity distribution and detection resistance. Eight copper tapes (copper foil tapes) are attached to the inner surface as contact electrodes to form an edge electrode array. Real-time conductivity distribution images can be generated under electrical impedance tomography (EIT) technology, and a pressure distribution thermogram is obtained through a pressure-conductivity mapping model. In leakage scenarios, the middle functional ring of the flange gasket will adsorb a large amount of leakage material due to the porous structure and sensitive material. While mitigating the leakage rate to some extent, the adsorbed leakage material will significantly change its dielectric constant distribution, thereby affecting the detection capacitance of the eight planar interdigitated capacitive sensing arrays embedded in the middle ring. The dielectric constant distribution information obtained by fitting eight capacitance values ​​can be used to effectively monitor the distribution of leakage components through a transport medium-dielectric constant correlation model. Therefore, by analyzing the inner loop resistance information, the current fastening pressure distribution can be determined, while by analyzing the middle loop capacitance information, the current leakage situation can be assessed.

[0055] The method for preparing the self-sensing flange gasket for structural health monitoring of a pipeline system includes the following steps:

[0056] Step 1): Design a ring-shaped complementary mold with different functional layers and transmission circuit substrates using SolidWorks (outer ring functional layer (sealing and strengthening outer ring layer 3) with inner and outer diameters of 255mm and 280mm, and a height of 5.5mm; middle ring functional layer (leak detection middle ring layer 2-1) with inner and outer diameters of 235mm and 255mm, and a height of 4.5mm; inner ring functional layer (sealing inner ring layer 1-1) with inner and outer diameters of 210mm and 235mm, and a height of 5mm; inner ring circuit substrate (inner ring edge electrode layer 1-2) with inner and outer diameters of 210mm and 235mm, and a height of 0.5mm; middle ring circuit substrate (middle ring planar interdigitated electrode layer 2-2) with inner and outer diameters of 235mm and 255mm, and a height of 1mm), and obtain the corresponding aluminum alloy metal mold using CNC machine tool precision machining technology.

[0057] Step 2): First, mix the silane prepolymer and toluene at a 1:1 mass ratio and stir magnetically for 2 hours to obtain mixture I. Simultaneously, mix an appropriate amount of CB particles (carbon black particles) and toluene at a 1:15 mass ratio and ultrasonically disperse until the CB particles are completely dissolved in the toluene to obtain mixture II. Mixtures I and II are then uniformly mixed, magnetically stirred for 30 minutes, and slowly heated until the toluene completely evaporates. Subsequently, a crosslinking agent is added dropwise to obtain a viscous, stable, conductive composite material.

[0058] Step 3): Slowly pour the uniformly mixed conductive composite material CB / PDMS into the inner ring functional layer (sealing inner ring layer) mold and the outer ring functional layer (sealing and reinforcing outer ring layer) mold. After removing the internal air bubbles with a vacuum machine, place it on a hot plate and heat until it solidifies. After cooling, demold to obtain a conductive sealing ring with piezoresistive characteristics.

[0059] Step 4): Mix granulated sugar granules (500μm) and erythritol powder at a ratio of 20:1, pour the mixture into the intermediate ring functional layer mold, and heat in an oven at 135℃ for 2 hours until the erythritol melts and binds the granulated sugar granules to form a whole. After cooling to room temperature in a vacuum chamber, pour in a uniformly mixed liquid PDMS / toluene solution (silane prepolymer: crosslinking agent: toluene = 10:1:20), remove internal air bubbles using a vacuum machine, and heat on a hot plate until solidified to obtain a PDMS-filled sugar template. Immerse the entire mold in deionized water for water bath heating. After the granulated sugar granules and erythritol powder are completely dissolved, demold the porous PDMS functional layer, wash it, and dry it at room temperature. Coat the surface of the porous PDMS functional layer with a specific nanofilm sensitive to the pipeline transport medium using electrochemical deposition technology. After removal, rinse with deionized water and dry at room temperature to obtain a porous sensitive layer with a sensitive specific film coated on the surface, i.e., the leak detection intermediate ring layer.

[0060] Step 5): Pour the uniformly mixed PDMS (silane prepolymer: crosslinking agent = 10:1) into the inner ring circuit mold, remove internal air bubbles using a vacuum machine, place it on a hot plate and heat until solidified, and demold after cooling to obtain the inner ring edge electrode array substrate; attach a certain number of uniformly distributed circular copper electrodes and corresponding copper wire leads to its upper surface; spin coat a CB / PDMS composite liquid phase film (100μm) on the upper surface using a spin coater, and use the self-adhesion property between the liquid and solid phases of the PDMS substrate material to achieve seamless and stable assembly of the inner ring edge electrode layer and the sealed inner ring functional layer.

[0061] Step 6): Design the photolithographic pattern of the planar interdigitated electrodes using SolidWorks (line width 0.5mm, line spacing 0.5mm, finger length 8.5mm, 4 pairs of interdigitates, overall size 10*8mm), and process it into a film. Use photoresist (SU-8 3050) to fabricate the corresponding photolithographic mold array on a 4-inch silicon wafer, including pre-baking, soft baking, exposure, post-baking, washing, and hard baking steps, ultimately obtaining multiple sets of planar interdigitated patterns with a thickness of 500μm. The planar interdigitated patterns on the silicon wafers were divided using a laser dicing machine, so that the area of ​​each silicon wafer with an interdigitated pattern was 9*12mm. These wafers were then uniformly arranged in a circle at the bottom of the intermediate ring circuit mold. A uniformly mixed liquid PDMS (silane prepolymer: crosslinking agent = 10:1) was poured into the inner ring circuit mold. After removing internal air bubbles using a vacuum machine, the mold was placed on a hot plate and heated until solidified. After cooling, the wafer was demolded to obtain the intermediate ring embedded planar interdigitated electrode array substrate. The CB / PDMS conductive composite material was scraped into the microchannel interdigitated patterns of the substrate. After heating and curing, a stable electrode connection could be achieved. Two metal signal lines were penetrated through the flexible substrate and contacted with one interdigitated electrode in the microchannel structure. The liquid PDMS was used to encapsulate the penetration points on the flexible substrate. For each interdigitated electrode, a layer of CB / PDMS composite liquid phase film (100μm) was uniformly spin-coated on the side with the interdigitated pattern using a spin coater. Similarly, the self-adhesive properties between the liquid and solid phases of the PDMS substrate material were used to achieve a seamless and stable assembly between the intermediate ring interdigitated electrode layer and the leakage detection intermediate ring functional layer.

[0062] Step 7): Apply a layer of liquid PDMS evenly to the inner sealing ring layer, the leak detection intermediate ring layer, and the sealing reinforcement outer ring layer. Arrange the three functional layers into a concentric ring contact structure. Utilizing the self-adhesive properties of PDMS, the final self-sensing flange gasket can be formed after heat curing. At this point, the inner ring edge electrode layer and the intermediate ring planar interdigitated electrode layer are located on opposite sides of the self-sensing flange gasket, ensuring that the signal transmission channels do not interfere with each other and facilitating the design of subsequent signal processing circuits.

[0063] Example 2

[0064] like Figure 4 As shown, the pipeline structure health monitoring method based on self-sensing flange gaskets is as follows:

[0065] This invention achieves physical decoupling of multimodal signals through the structural division of two functional components. The sealing inner ring can sense the surface pressure distribution through its own piezoresistive effect. Using an inner ring edge electrode array and electrical impedance tomography (EIT), the current conductivity distribution of the sealing inner ring can be acquired in real time. Utilizing the pressure-conductivity mapping model determined in material characterization experiments, the conductivity distribution map can be converted into a pressure distribution thermogram, thus monitoring the pressure information of the self-sensing flange gasket. Simultaneously, the porous structure of the leak detection intermediate ring and the sensitive film coated on it significantly enhance the adsorption capacity for leaking substances. The adsorbed leaking substances change the dielectric constant of the overall intermediate ring. The multi-point real-time capacitance obtained through the interdigitated electrode array of the intermediate ring reflects this change and fits to obtain the dielectric constant distribution map of the current leak detection intermediate ring. Using the transport medium-dielectric constant correlation model determined in material characterization experiments, the dielectric constant distribution map can be converted into a leak component distribution thermogram, enabling the monitoring of leaks in the self-sensing flange gasket. For a single flange structure, by combining pressure information and media leakage status, intelligent identification algorithms can be used to achieve functions such as fault classification, severity determination, and early warning at a specific flange structure. If the temporal evolution law of a single flange structure is combined, the temporal iteration characteristics of its distribution information can be used to achieve more forward-looking functions such as precursor prediction and life estimation. If the spatial array distribution information of multi-point self-sensing flange gaskets in the pipeline network system is combined, more engineering-significant structural health monitoring functions such as fault source analysis and operation and maintenance plan formulation can be achieved.

[0066] Example 3

[0067] This embodiment establishes a test scenario for leakage in a transportation pipeline network to verify the effectiveness of the flange gasket in monitoring the specific flange structural condition. For example... Figure 5 As shown, a standard DN200 pipeline system was constructed, transporting water as the medium, with flange connections between the pipes. The specific flange connection structure is as follows. Figure 6 As shown, the inner and outer double-ring design improves sealing performance and provides emergency response time for leaks. The middle ring can directly respond to the leak by absorbing leaking components and slow down the leakage rate. Loosening the lower bolts of the middle flange structure simulates a loose interface. At this time, the pressure distribution output by the self-sensing flange gasket will change significantly, specifically, the lower tightening pressure will decrease. After a period of time, leakage begins to appear at the middle ring, and the amount of medium leakage detectable below the flange gasket will gradually increase. The tightening pressure distribution heatmap and leakage component distribution heatmap generated based on the flange gasket's electrical signal are shown below. Figure 7 As shown in the figure, the above phenomena can be directly observed, and the type and severity of the current flange structure failure can be easily determined. Therefore, this test effectively demonstrates the application value of this invention in flange structure failure detection.

[0068] Example 4

[0069] This embodiment verifies the effectiveness of flange gasket sensor networks in monitoring the structural health of pipeline systems by constructing a deformation test scenario for a transportation pipeline network. Figure 8 As shown, applying the same parallel thrust to two adjacent pipe sections will cause varying degrees of deformation in the three connected flange structures. Specifically, the flange structures on both sides will experience smaller deformations, while the flange structure directly connecting the two pipe sections will exhibit the largest deformations, with the deformation directions being opposite. Figure 9 As shown in the pressure distribution diagram, the strain change of the middle flange gasket is the largest, while the changes of the two side flange gaskets are roughly the same. The actual deformation state of the pipeline can be roughly inferred from the location of the openings. Furthermore, the heat map of leakage component distribution shows that a minor leak occurs in the middle structure, while the two side flanges maintain a tight seal despite this minor deformation. Therefore, by integrating and analyzing the pressure distribution of multiple flange gaskets and their spatial positions, more comprehensive information about the current pipeline system can be obtained, thereby enabling structural health monitoring of the entire pipeline network.

[0070] In summary, the self-sensing flange gasket designed in this invention, through a three-layer concentric ring contact structure, effectively achieves simultaneous measurement of fastening pressure distribution and leakage component distribution using multi-dimensional electrical information. It has a simple structure, mature manufacturing process, and good monitoring effect. It can realize fault state detection for specific flange structures and overall structural health monitoring for pipeline systems, meeting the engineering needs of pipeline system operation and maintenance.

[0071] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A self-sensing flange gasket for structural health monitoring of a pipeline system, characterized in that, It includes three concentrically arranged annular components, which, from the inside out, are an inner ring layer (1), a middle ring layer (2), and a sealing and reinforcing outer ring layer (3). The inner ring layer includes an inner ring edge electrode layer (1-2) and a sealing inner ring layer (1-1). The sealing inner ring layer (1-1) is used for sealing and protecting the conveying pipeline and detecting its own fastening pressure. The diameter of the inner ring edge electrode layer (1-2) is equal to the diameter of the sealing inner ring layer (1-1), and multiple contact electrodes for detecting the resistance change of the sealing inner ring layer (1-1) are uniformly arranged circumferentially. The exposed side of the contact electrode of the inner ring edge electrode layer (1-2) is in contact with the sealing inner ring layer (1-1). Each contact electrode is connected to a metal signal line for transmitting the resistance information detected by the contact electrode. The intermediate ring layer includes a leak detection intermediate ring layer (2-1) and an intermediate ring planar interdigitated electrode layer (2-2). The leak detection intermediate ring layer (2-1) is used to detect leaks. The diameter of the intermediate ring planar interdigitated electrode layer (2-2) is equal to the diameter of the leak detection intermediate ring layer (2-1), and multiple interdigitated electrodes are uniformly arranged circumferentially. When a leak occurs in the pipeline, the leaked substance contacts the leak detection intermediate ring layer (2-1) and causes a change in its capacitance. The exposed side of the interdigitated electrode of the intermediate ring planar interdigitated electrode layer (2-2) is in contact with the leak detection intermediate ring layer (2-1). Each interdigitated electrode is connected to two metal signal lines for transmitting the capacitance information detected by the interdigitated electrode. The sealing and reinforcing outer ring layer (3) is used for the double sealing of the conveying pipeline; The inner ring edge electrode layer (1-2) and the middle ring planar interdigitated electrode layer (2-2) are respectively disposed on the left and right sides of the flange gasket, and the number of the contact electrode and the interdigitated electrode is greater than or equal to 8. The inner sealing ring layer (1-1) and the outer sealing reinforcement ring layer (3) are made of conductive composite material CB / PDMS; the leak detection intermediate ring layer (2-1) is composed of a PDMS porous foam structure, and the PDMS porous foam structure is coated with a nano-thin film material sensitive to the transport medium of the delivery pipeline; the inner ring edge electrode layer (1-2) uses PDMS as a flexible substrate and attaches several copper foil tapes as contact electrodes to the surface; the intermediate ring planar interdigitated electrode layer (2-2) uses PDMS as a flexible substrate, and the flexible substrate has a planar interdigitated microchannel structure, and interdigitated electrodes are formed by filling CB / PDMS into the planar interdigitated microchannel structure; The inner sealing ring layer (1-1) is flexible and conductive, and will change its conductivity distribution under external pressure; The sealing and reinforcing outer ring layer (3) is flexible and will undergo elastic deformation under external pressure to achieve sealing; The leak detection intermediate ring layer (2-1) can adsorb the leaked pipeline transport medium and change its own dielectric constant distribution; The inner ring edge electrode layer (1-2) can obtain the fastening pressure distribution information of the sealing inner ring layer (1-1) by acquiring the resistance distribution of the sealing inner ring layer; The intermediate ring planar interdigitated electrode layer (2-2) can obtain the leakage component distribution information of the leakage detection intermediate ring layer (2-1) by acquiring the capacitance distribution of the leakage detection intermediate ring layer (2-1).

2. The self-sensing flange gasket for structural health monitoring of a pipeline system according to claim 1, characterized in that, The height of the inner ring layer (1) is equal to the height of the sealing and reinforcing outer ring layer (3); the height of the middle ring layer (2) is less than or equal to the height of the sealing and reinforcing outer ring layer (3).

3. A method for preparing a self-sensing flange gasket for structural health monitoring of a pipeline system as described in claim 1, characterized in that, Includes the following steps: Step 1): Design and obtain five different sizes of circular ring molds; Step 2): Mix the silane prepolymer with toluene to obtain mixture I, and simultaneously mix the CB particles with toluene to obtain mixture II; mix mixture I and mixture II uniformly and heat until the toluene is completely evaporated, then add a crosslinking agent dropwise to obtain a viscous, stable conductive composite material CB / PDMS; Step 3): Pour the viscous, stable conductive composite material CB / PDMS into the molds of the sealing inner ring layer and the sealing and reinforcing outer ring layer, respectively. Remove internal air bubbles, heat to cure, cool, and demold to obtain the sealing inner ring layer and the sealing and reinforcing outer ring layer with piezoresistive properties. Step 4): Pour the uniformly mixed granulated sugar and erythritol powder into the mold of the leak detection intermediate ring layer, and heat to make the erythritol and granulated sugar particles adhere to form a sugar cake; then pour the PDMS / toluene solution into the mold of the leak detection intermediate ring layer to completely fill the gaps inside the sugar cake, remove internal air bubbles, and heat to solidify, obtaining a PDMS-filled sugar cake; then immerse the PDMS-filled sugar cake in deionized water and heat to obtain porous PDMS; demold the porous PDMS, wash and dry it, and coat the surface of the porous PDMS with a nanofilm material sensitive to the pipeline transport medium, then rinse with deionized water and dry to obtain the leak detection intermediate ring layer; wherein, the mass ratio of silane prepolymer: crosslinking agent: toluene in the PDMS / toluene solution is 10:1:15~30; Step 5): Pour the uniformly mixed liquid PDMS into the mold of the inner ring edge electrode layer, remove internal air bubbles, heat to cure, cool, and demold to obtain a flexible substrate of the inner ring edge electrode layer; attach several circumferentially uniformly distributed contact electrodes to the upper surface of the flexible substrate; encapsulate several metal signal lines with the contact electrodes respectively; then coat the surface of the flexible substrate with the attached contact electrodes with a layer of the viscous stable conductive composite material CB / PDMS, and use the self-adhesive property between the liquid and solid phases of PDMS to achieve seamless and stable assembly of the inner ring edge electrode layer and the sealed inner ring layer. Step 6): Design a photolithographic pattern for a planar interdigitated microchannel structure and process it into a film. After pre-baking, soft baking, exposure, post-baking, washing, and hard baking, a photolithographic mold with multiple sets of planar interdigitated patterns is obtained. The planar interdigitated patterns on the photolithographic mold are divided to obtain multiple small photolithographic molds with the same planar interdigitated pattern. These small photolithographic molds are evenly distributed circumferentially at the bottom of the mold with the intermediate ring interdigitated electrode layer. Then, a uniformly mixed liquid PDMS is poured into the mold, internal air bubbles are removed, and the mixture is heated to solidify, cooled, and demolded to obtain an intermediate ring planar interdigitated electrode with an embedded microchannel structure. A flexible substrate is formed by coating a viscous, stable conductive composite material CB / PDMS into the microchannel structure of the flexible substrate to form a central ring planar interdigitated electrode layer. Two metal signal lines are penetrated through the flexible substrate and contacted with an interdigitated electrode in the microchannel structure. The liquid PDMS is used to encapsulate the penetration points on the flexible substrate, and each interdigitated electrode is encapsulated with metal signal lines. A layer of the composite material CB / PDMS liquid phase film obtained in step 2) is uniformly spin-coated on one side with a planar interdigitated pattern, so that the central ring interdigitated electrode layer and the leakage detection central ring layer can achieve self-adhesive and stable assembly. Step 7): Apply a layer of liquid PDMS evenly to the inner sealing ring layer, the leak detection intermediate ring layer, and the sealing reinforcement outer ring layer, and assemble them all together to form a concentric ring contact structure. Then heat and cure to form the final self-sensing flange gasket. At this time, the inner ring edge electrode layer and the intermediate ring planar interdigitated electrode layer are located on opposite sides of the self-sensing flange gasket.

4. The method for preparing a self-sensing flange gasket for structural health monitoring of a pipeline system according to claim 3, characterized in that, In step 2), the mass ratio of silane prepolymer to toluene is 1:1~2, the mass ratio of CB particles to toluene is 1:10~20, and the mass ratio of silane prepolymer: crosslinking agent: CB particles in the obtained stable conductive composite material is 10:1:1.94~3.66; in steps 5) and 6), the mass ratio of silane prepolymer to crosslinking agent in the uniformly mixed liquid phase PDMS is 10:

1.

5. A method for structural health monitoring of a pipeline system based on the self-sensing flange gasket described in claim 1, characterized in that, Includes the following steps: Step S1: Install the self-sensing flange gasket at one or more flange connection structures that need to be detected in the pipeline. Each self-sensing flange gasket is equipped with an electrical signal reading module, which is connected to all metal signal lines to read the sensing data of the self-sensing flange gasket. The sensing data includes the resistance information R of the sealing inner ring layer and the capacitance information C of the leakage detection intermediate ring layer. Several self-sensing flange gaskets are grouped into a unit group and a signal transmission station is configured. The sensing data of all self-sensing flange gaskets connected to it are uploaded to the terminal server through the signal transmission station. Step S2: When an unknown fault occurs in the pipeline, the sensing data of the self-sensing flange gasket in the fault area will fluctuate significantly. When the abnormal value in the sensing data reaches a certain threshold, an alarm signal will be directly triggered, and the sensing data of the self-sensing flange gasket at the abnormal point corresponding to the abnormal value will be decoded and analyzed on the terminal server. Step S3: The decoding analysis involves calculating the actual tightening pressure distribution and leakage component distribution information from the electrical signals in the sensor data of the self-sensing flange gasket; using the piezoresistive effect of the sealing inner ring layer and electrical impedance tomography, the conductivity distribution map caused by the tightening pressure is obtained; then, a thermal map of the tightening pressure distribution of the self-sensing flange gasket is drawn using a conductivity-pressure mapping model; when a micro-leak occurs in the pipeline, the PDMS porous foam structure of the leak detection intermediate ring layer adsorbs the leaked pipeline transport medium, and changes the local dielectric distribution of the leak detection intermediate ring layer according to the magnitude and radiation area of ​​the adsorbed leaked substance; the capacitance information detected by the interdigitated electrodes directly reflects the change in the dielectric constant of the leak detection intermediate ring layer, and a thermal map of the leakage component distribution of the self-sensing flange gasket is drawn using a dielectric constant-transport medium mapping model; by combining the thermal map of the tightening pressure distribution and the thermal map of the leakage component distribution, the current fault manifestation is determined; Step S4: Combining the heat map of fastening pressure distribution and the heat map of leakage component distribution can further determine the fault type and assess the severity of the fault, which helps to formulate targeted fault handling solutions; based on the time evolution law of the sensing data of a single self-sensing flange gasket, the life cycle analysis and fault precursor prediction of a single self-sensing flange gasket can be realized; by using the spatial data of multiple sets of self-sensing flange gaskets in the pipeline system, combined with the spatial location information of each self-sensing flange gasket, a series of problems existing in the pipeline system can be comprehensively evaluated, thereby realizing the structural health monitoring of the pipeline system.

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