Gas cylinder having structural health self-sensing monitoring function, manufacturing method therefor, and gas cylinder system

Abstract

A gas cylinder having a structural health self-sensing monitoring function, a manufacturing method therefor, and a gas cylinder system. The gas cylinder comprises a liner, a carbon fiber winding layer, a glass fiber insulating layer, an intelligent sensing layer and a glass fiber protective layer being successively stacked on the outer surface of the liner. The carbon fiber winding layer contains carbon fibers and cured resin I; the glass fiber insulating layer contains glass fibers I and cured resin II; the intelligent sensing layer contains glass fiber bundles, cured epoxy resin and few-layer graphene dispersed in the cured epoxy resin; the glass fiber protective layer contains glass fibers II and cured resin III. While the strength and airtightness of the winding layer of the gas cylinder can be improved, by means of the resistance / strain response effect of the winding layer and electrical resistance tomography, in-situ, online and full-lifetime structural health self-sensing monitoring of the gas cylinder can be implemented without disassembling the gas cylinder, thereby achieving real-time structural sensing and damage monitoring and location of the gas cylinder.

Description

Gas cylinder with structural health self-sensing monitoring function, preparation method thereof, and gas cylinder system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202311113250.1 filed on August 31, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of pressure vessels and health monitoring, and in particular to a gas cylinder with a structural health self-sensing monitoring function, a preparation method thereof, and a gas cylinder system. Background Art

[0004] In recent years, high-pressure gas cylinders, key components of hydrogen fuel cell vehicle hydrogen supply systems, have been evolving toward higher pressures and lighter weights. This has placed higher demands on the safety of pressure vessels. Traditional design and manufacturing techniques alone are no longer sufficient to meet these service safety requirements. Developing health monitoring technology for composite pressure vessels is crucial for preventing sudden structural failure and ensuring their safety throughout their lifecycle.

[0005] Some non-destructive testing technologies, such as X-ray detection and infrared imaging, can detect damage and defects that may occur in composite materials structures. However, most of the above non-destructive testing methods can only be used for offline testing and it is difficult to detect damage in hidden parts.

[0006] Huang Liang et al. (Huang Liang, Jin Mingzhe, He Qi, et al. Research on X-ray digital imaging detection method for large-volume fiber-wound gas cylinders [J]. Composite Materials Science and Engineering, 2020, (03): 84-89.) For large-volume steel liner fiber-wound gas cylinders, artificial defects such as fiber grooves, fiber holes, liner holes, and liner grooves were created on the cylinders, and an X-ray digital imaging detection method was used to conduct experimental research, as shown in Figure 1, to detect cylinder defects offline through X-ray imaging. The experimental results show that digital rays have a certain ability to detect various defects in large-volume fiber-wound gas cylinders. However, the use of traditional non-destructive testing technology can only perform offline, static, and passive testing, which makes it difficult to find problems during the use of pressure vessels and difficult to detect damage to hidden parts.

[0007] Xiao Biao et al. (Xiao Biao, Yang Bin, Hu Chaojie, et al. Health monitoring of fiber-wound pressure vessels based on embedded strain gauges [J]. Journal of High Pressure Physics, 2019, 33(04): 56-6) During the preparation of glass fiber wound metal liner composite pressure vessels, strain sensors were embedded between the metal liner and the glass fiber / epoxy resin composite layer to obtain a fiber-wound pressure vessel with in-situ monitoring function.

[0008] Qing X (Qing X, Beard S, Kumar A, et al. Advances in the development of a built-in diagnostic system for filament wound composite structures [J]. Composites Science and Technology, 2006, 66(11-12): 1694-1702) developed a comprehensive structural health monitoring system based on piezoelectric elements. The system includes a built-in sensor network, supporting diagnostic hardware, and data processing / analysis software, as shown in Figure 2. The system incorporates a piezoelectric smart interlayer embedded in a composite gas cylinder. Signal acquisition results demonstrate that the pressure-sensitive smart interlayer can effectively monitor and locate impact damage as small as half an inch in diameter.

[0009] CN113776587A discloses a vehicle-mounted hydrogen storage bottle service monitoring device and method based on optical fiber sensing. By winding an optical fiber Bragg grating with a strain sensor on the surface of the hydrogen storage bottle liner and the surface of the winding layer, a hydrogenation gun is connected to an optical fiber flange to sense, demodulate and analyze the dual deformation signals of the hydrogen storage bottle liner inflation deformation and the composite material structure deformation of the hydrogen storage bottle, and monitor the stress and strain of the hydrogen storage bottle in real time, as shown in Figure 3. In the figure: 1 is an optical fiber Bragg grating with a sensor; 2 is the inner liner of the hydrogen storage bottle; 3 is the composite material on the surface of the inner liner; 4 is the hydrogen storage bottle; 5 is the characteristic QR code of the hydrogen storage bottle body; 6 is the optical fiber Bragg grating with a sensor outlet at the bottle valve of the hydrogen storage bottle; 7 is the optical fiber flange interface of the hydrogenation gun; 8 is the hydrogenation gun; 9 is the bottle valve of the hydrogen storage bottle; 10 is the host computer cloud platform.

[0010] Although all of the above methods can achieve a certain online health monitoring effect by pre-embedding sensors inside the composite material, without exception, the implantation of sensors will cause large defects in the winding layer during the preparation of the gas cylinder, posing a challenge to the structural safety of the gas cylinder.

[0011] In addition, these built-in sensors are relatively independent of the structure itself. The large number of sensors increases the weight of the structure and the difficulty of installation. There are also problems such as low strain tolerance, sensitivity to the service environment, and difficulty in matching the mechanical properties of the structure with composite materials, resulting in loss of the original performance of composite structural parts.

[0012] Summary of the Invention

[0013] The present invention aims to overcome the poor safety performance of existing pressure vessels with online health monitoring capabilities. It provides a gas cylinder with self-sensing structural health monitoring, a method for manufacturing the same, and a gas cylinder system. This cylinder improves the strength and airtightness of the wrapping layer while leveraging its resistance / strain response to achieve in-situ self-sensing structural health monitoring.

[0014] To achieve the above objectives, the present invention provides, in a first aspect, a gas cylinder with a structural health self-sensing monitoring function, the gas cylinder comprising an inner liner, and a carbon fiber winding layer, a glass fiber insulation layer, an intelligent sensing layer, and a glass fiber protective layer sequentially stacked on the outer surface of the inner liner; wherein:

[0015] The carbon fiber winding layer contains carbon fibers and a cured resin I;

[0016] The glass fiber insulation layer contains glass fiber I and cured resin II;

[0017] The smart sensing layer comprises glass fiber bundles, cured epoxy resin, and few-layer graphene dispersed in the cured epoxy resin;

[0018] The glass fiber protective layer contains glass fiber II and curing resin III.

[0019] A second aspect of the present invention provides a method for preparing the gas cylinder with the structural health self-sensing monitoring function according to the first aspect, the method comprising the following steps:

[0020] (1) Preparation of carbon fiber winding layer: Winding carbon fiber impregnated with resin I and curing agent I on the outer surface of the inner liner to obtain a prefabricated gas cylinder I;

[0021] (2) Preparation of glass fiber insulation layer: Winding glass fiber I impregnated with resin II and curing agent II on the outer surface of the prefabricated gas cylinder I to obtain prefabricated gas cylinder II;

[0022] (3) Preparation of the intelligent sensing layer: coating the outer surface of the prefabricated gas cylinder II with a gel mixture containing a few-layer graphene, an epoxy resin, and a curing agent III to form a coating layer, and then winding a glass fiber bundle around the outer surface of the coating layer to form a glass fiber bundle layer, wherein the coating and winding are performed alternately to obtain a prefabricated gas cylinder III;

[0023] (4) Preparation of a glass fiber protective layer: Winding glass fiber II impregnated with resin III and curing agent IV on the outer surface of the prefabricated gas cylinder III to obtain a prefabricated gas cylinder IV;

[0024] (5) The prefabricated gas cylinder IV is subjected to a curing treatment.

[0025] A third aspect of the present invention provides a gas cylinder system with a structural health self-sensing monitoring function, the gas cylinder system comprising a gas cylinder, an electrode sensing unit, an excitation signal control unit, a data acquisition unit, and an image reconstruction unit; wherein, the gas cylinder is the gas cylinder with a structural health self-sensing monitoring function as described in the first aspect.

[0026] Through the above technical solution, the present invention has the following advantages:

[0027] 1. The gas cylinder provided by the present invention includes an inner liner, and the outer surface of the inner liner is sequentially laminated with a carbon fiber winding layer, a glass fiber insulation layer, an intelligent sensing layer, and a glass fiber protective layer. The intelligent sensing layer contains glass fiber bundles, a resin matrix, and few-layer graphene dispersed in the resin matrix. While improving the strength and airtightness of the winding layer, the intelligent sensing layer utilizes its resistance / strain response effect and, with the help of electrical resistance tomography technology, can achieve in-situ, online, and lifelong self-sensing structural health monitoring of the gas cylinder without disassembling the gas cylinder, thereby realizing real-time structural perception, damage monitoring, and location of the gas cylinder.

[0028] 2. The gas cylinder provided by the present invention has excellent mechanical properties. The two-dimensional few-layer graphene filler has a good aspect ratio, ultra-high specific surface area, rough surface, and wrinkles. The addition of an appropriate amount of few-layer graphene not only does not damage the original structural strength of the gas cylinder, but can also significantly improve the mechanical properties of the matrix polymer material and enhance the structural safety performance of the gas cylinder.

[0029] 3. The gas cylinder provided by the present invention has excellent gas barrier properties. The defect-free few-layer graphene has an excellent gas barrier effect. The few-layer graphene uniformly dispersed in the resin matrix can form a barrier network, increase the diffusion path length, limit the diffusion of molecules in the matrix, improve the barrier properties of the polymer, and further ensure the airtightness of the gas cylinder.

[0030] 4. Few-layer graphene / polymer composites have improved electrical conductivity by several orders of magnitude. Glass fiber and resin matrices are both insulators, but when the content of few-layer graphene in the polymer reaches its percolation threshold, a conductive network can be formed, causing a sudden change in the conductivity of the composite material. Using two-dimensional few-layer graphene as the conductive network carrier for electrical resistance tomography technology makes the conductive network more uniform and stable, which has greater advantages in practical applications.

[0031] 5. The preparation method provided by the present invention is simple and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of a double-wall single-shadow vertical transillumination test arrangement of the prior art;

[0033] FIG2 is a schematic diagram of the embedding position of a smart interlayer in a wrapped gas cylinder according to the prior art;

[0034] FIG3 is a connection diagram of a monitoring and diagnosis evaluation cloud platform of the prior art;

[0035] FIG4 is a schematic diagram of a gas cylinder with a structural health self-sensing monitoring function according to a specific embodiment of the present invention;

[0036] FIG5 is a schematic diagram of a gas cylinder with a structural health self-sensing monitoring function according to a specific embodiment of the present invention;

[0037] FIG6 is a schematic diagram of a gas cylinder system with a structural health self-sensing monitoring function according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0038] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0039] In the present invention, unless otherwise specified, the room temperature refers to 25±2°C.

[0040] In the present invention, the two ends of the gas cylinder refer to "the end where the bottle mouth of the gas cylinder is located and the end opposite to the bottle mouth".

[0041] A first aspect of the present invention provides a gas cylinder with a structural health self-sensing monitoring function, the gas cylinder comprising an inner liner, and a carbon fiber winding layer, a glass fiber insulation layer, an intelligent sensing layer, and a glass fiber protective layer are sequentially stacked on the outer surface of the inner liner; wherein:

[0042] The carbon fiber winding layer contains carbon fibers and a cured resin I;

[0043] The glass fiber insulation layer contains glass fiber I and cured resin II;

[0044] The smart sensing layer comprises glass fiber bundles, cured epoxy resin, and few-layer graphene dispersed in the cured epoxy resin;

[0045] The glass fiber protective layer contains glass fiber II and curing resin III.

[0046] Preferably, based on the total weight of the carbon fiber winding layer, the content of the carbon fiber is 63-68 wt%.

[0047] Preferably, based on the total weight of the glass fiber insulation layer, the content of the glass fiber I is 60-70 wt%.

[0048] Preferably, based on the total weight of the smart sensing layer, the content of the glass fiber bundle is 54-70wt%, the content of the cured epoxy resin is 27-46wt%, and the content of the few-layer graphene is 0.07-2.5wt%.

[0049] Preferably, based on the total weight of the glass fiber protective layer, the content of the glass fiber II is 60-70 wt%.

[0050] Preferably, the weight content ratio of the carbon fiber winding layer, the glass fiber insulation layer, the intelligent sensing layer and the glass fiber protective layer is 1:0.4-0.85:0.65-0.98:0.2-0.45.

[0051] According to some embodiments of the present invention, preferably, the material of the liner is metal and / or plastic; wherein the metal is selected from at least one of aluminum alloy, magnesium alloy and titanium alloy, preferably aluminum alloy; the plastic is at least one of nylon, high-density polyethylene and modified polyethylene, preferably nylon.

[0052] According to some embodiments of the present invention, the thickness of the carbon fiber winding layer can be determined according to actual needs. Preferably, the thickness of the carbon fiber winding layer is 4-18 mm.

[0053] According to some embodiments of the present invention, preferably, in the carbon fiber winding layer, the carbon fibers are polyacrylonitrile-based carbon fibers; and the tow size of the polyacrylonitrile-based carbon fibers is 12K to 24K.

[0054] According to some embodiments of the present invention, preferably, in the carbon fiber winding layer, the cured resin I is obtained by curing a mixture containing resin I and curing agent I.

[0055] Preferably, the resin I is selected from epoxy resins and / or vinyl resins.

[0056] Preferably, the curing agent I is at least one selected from triethylenetetramine, tertiary amine titanate, modified polyetheramine and methyl ethyl ketone peroxide.

[0057] According to some embodiments of the present invention, preferably, the glass fiber insulation layer has a thickness of 4-10 mm.

[0058] According to some embodiments of the present invention, preferably, the glass fiber I is E-glass fiber.

[0059] According to some embodiments of the present invention, preferably, in the glass fiber insulation layer, the cured resin II is obtained by curing a mixture containing resin II and curing agent II.

[0060] Preferably, the resin II is selected from epoxy resins and / or vinyl resins.

[0061] Preferably, the curing agent II is at least one selected from triethylenetetramine, tertiary amine titanate, modified polyetheramine and methyl ethyl ketone peroxide.

[0062] According to some embodiments of the present invention, preferably, the thickness of the smart sensing layer is 6 mm to 12 mm.

[0063] According to some embodiments of the present invention, the few-layer graphene preferably has a thickness of 2-10 nm and a lateral dimension of 10-50 μm. Compared to spherical or tubular conductive nanomaterials such as carbon black and carbon nanotubes, sheet-like two-dimensional few-layer graphene is less prone to aggregation and entanglement, and is more conducive to forming a uniform and stable conductive network.

[0064] According to some embodiments of the present invention, preferably, in the smart sensing layer, the cured epoxy resin is obtained by curing a mixture containing an epoxy resin and a curing agent III.

[0065] Preferably, the curing agent III is at least one of triethylenetetramine, tertiary amine titanate and modified polyetheramine.

[0066] According to some embodiments of the present invention, the smart sensing layer preferably further comprises a dispersant selected from cetylpyridinium chloride and / or polyvinylpyrrolidone, preferably polyvinylpyrrolidone. This preferred embodiment further promotes the dispersion of the few-layer graphene in the cured epoxy resin, while also further improving the conductivity of the smart sensing layer and the strength and airtightness of the gas cylinder.

[0067] According to some embodiments of the present invention, preferably, in the smart sensing layer, the content of the dispersant is 2-6.5 wt % of the content of the few-layer graphene.

[0068] According to some embodiments of the present invention, preferably, the thickness of the glass fiber protective layer is 2-5 mm.

[0069] According to some embodiments of the present invention, preferably, the glass fiber II is selected from E-glass fiber and / or S-glass fiber.

[0070] According to some embodiments of the present invention, preferably, in the glass fiber protective layer, the cured resin III is obtained by curing a mixture containing resin III and curing agent IV.

[0071] Preferably, the resin III is selected from epoxy resins and / or vinyl resins.

[0072] Preferably, the curing agent IV is at least one selected from triethylenetetramine, tertiary amine titanate, modified polyetheramine and methyl ethyl ketone peroxide.

[0073] According to some embodiments of the present invention, the content of each component in the carbon fiber winding layer, the glass fiber insulation layer, the smart sensing layer and the glass fiber protective layer is calculated by the input amount (dosage) of the raw materials.

[0074] A second aspect of the present invention provides a method for preparing the gas cylinder with the structural health self-sensing monitoring function according to the first aspect, the method comprising the following steps:

[0075] (1) Preparation of carbon fiber winding layer: Winding carbon fiber impregnated with resin I and curing agent I on the outer surface of the inner liner to obtain a prefabricated gas cylinder I;

[0076] (2) Preparation of glass fiber insulation layer: Winding glass fiber I impregnated with resin II and curing agent II on the outer surface of the prefabricated gas cylinder I to obtain prefabricated gas cylinder II;

[0077] (3) Preparation of the intelligent sensing layer: coating the outer surface of the prefabricated gas cylinder II with a gel mixture containing a few-layer graphene, an epoxy resin, and a curing agent III to form a coating layer, and then winding a glass fiber bundle around the outer surface of the coating layer to form a glass fiber bundle layer, wherein the coating and winding are performed alternately to obtain a prefabricated gas cylinder III;

[0078] (4) Preparation of a glass fiber protective layer: Winding glass fiber II impregnated with resin III and curing agent IV on the outer surface of the prefabricated gas cylinder III to obtain a prefabricated gas cylinder IV;

[0079] (5) The prefabricated gas cylinder IV is subjected to a curing treatment.

[0080] According to some embodiments of the present invention, preferably, the winding method in step (1) is circumferential winding and / or spiral winding, and preferably circumferential winding and spiral winding are performed alternately, that is, first circumferential winding, then spiral winding, and then circumferential winding, and so on. The angle of the circumferential winding is 85°-90°, and the angle of the spiral winding is 9°-60°.

[0081] According to some embodiments of the present invention, preferably, the number of layers of winding in step (1) is 6-30 layers.

[0082] According to some embodiments of the present invention, preferably, in step (1), the weight ratio of the carbon fiber to the resin I is 1.81-2.47:1.

[0083] According to some embodiments of the present invention, preferably, in step (1), the weight ratio of the curing agent I to the resin I is 0.03-0.2:1.

[0084] According to some embodiments of the present invention, preferably, the winding method in step (2) is spiral winding, and the angle of the spiral winding is 12°-40°.

[0085] According to some embodiments of the present invention, preferably, the number of layers of winding in step (2) is 8-20 layers.

[0086] According to some embodiments of the present invention, preferably, in step (2), the weight ratio of the glass fiber I to the resin II is 1.81-2.36:1.

[0087] According to some embodiments of the present invention, preferably, in step (2), the weight ratio of the curing agent II to the resin II is 0.03-0.2:1.

[0088] According to some embodiments of the present invention, preferably, the winding method in step (3) is spiral winding, and the angle of the spiral winding is 25°-50°.

[0089] According to some embodiments of the present invention, preferably, the diameter of the spirally wound polar hole in step (3) is larger than the diameter of the bottle mouth of the gas cylinder.

[0090] According to some embodiments of the present invention, preferably, the number of glass fiber bundle layers in step (3) is 10-20 layers.

[0091] According to some embodiments of the present invention, preferably, the boundary of the coating in step (3) coincides with the position of the wound pole hole.

[0092] According to some embodiments of the present invention, preferably, in step (3), the amount of the few-layer graphene used is 0.2-6 wt % of the amount of the epoxy resin used. Adopting the above preferred embodiment is conducive to further improving the conductivity of the smart sensing layer, and further improving the strength and airtightness of the gas cylinder.

[0093] According to some embodiments of the present invention, preferably, in step (3), the amount of the curing agent III is 10-30 wt % of the amount of the epoxy resin.

[0094] According to some embodiments of the present invention, preferably, in step (3), the method for preparing the gel mixture comprises: dispersing the few-layer graphene in the epoxy resin, and then mixing the obtained resin mixture with the curing agent III.

[0095] According to some embodiments of the present invention, preferably, in step (3), the dispersing step includes: in the presence of an organic solvent, contacting the few-layer graphene with a dispersant and performing a primary ultrasonic treatment to obtain a mixture; drying the epoxy resin to remove moisture in the epoxy resin, then contacting the mixture with the epoxy resin and performing a secondary ultrasonic treatment, and then vacuum drying the obtained dispersion to remove the organic solvent.

[0096] Preferably, the organic solvent is ethanol and / or propanol.

[0097] Preferably, the amount of the dispersant used is 2-6.5 wt % of the amount of the few-layer graphene used.

[0098] Preferably, the time of the first-stage ultrasonic treatment is 10-100 min.

[0099] Preferably, the drying conditions include: a drying time of 20-60 minutes and a drying temperature of 80-125°C.

[0100] Preferably, the secondary ultrasonic treatment lasts for 30 min to 1.5 h.

[0101] Preferably, the vacuum drying conditions include: temperature of 60-80° C. and time of 10-120 min.

[0102] According to some embodiments of the present invention, preferably, after the coating and the winding of step (3) are completed, step (3) further includes the step of extracting the electrode, including:

[0103] The product obtained by alternately performing the coating and the winding is cured at room temperature for 8-36 hours. After the surface becomes sticky, the multiple electrodes in the electrode group and the opposite electrode group are respectively compounded on the boundaries of the smart sensing layer at both ends of the gas cylinder through conductive silver paste to collect the boundary voltage of the smart sensing layer; preferably, the electrode is copper foil.

[0104] According to some embodiments of the present invention, preferably, in step (4), the winding method is circumferential winding and / or spiral winding, and preferably circumferential winding and spiral winding are performed alternately, that is, first circumferential winding, then spiral winding, and then circumferential winding, and so on. The angle of the circumferential winding is 85-90°, and the angle of the spiral winding is 12°-40°.

[0105] According to some embodiments of the present invention, preferably, the number of layers of winding in step (4) is 4-10 layers.

[0106] According to some embodiments of the present invention, preferably, the diameter of the polar hole of the spiral winding in step (4) is smaller than the diameter of the polar hole of the spiral winding in step (3). The above preferred embodiment is conducive to achieving comprehensive protection of the smart sensing layer by the glass fiber protective layer.

[0107] According to some embodiments of the present invention, preferably, the angle of the spiral winding in step (4) is smaller than the angle of the spiral winding in step (3). The above preferred embodiment is conducive to ensuring that the pole hole diameter in step (4) meets the requirements.

[0108] According to some embodiments of the present invention, preferably, in step (4), the weight ratio of the glass fiber II to the resin III is 1.67-2.36:1.

[0109] According to some embodiments of the present invention, preferably, in step (4), the weight ratio of the curing agent IV to the resin III is 0.03-0.2:1.

[0110] According to some embodiments of the present invention, preferably, in step (5), the curing treatment conditions include: a curing temperature of 70-180° C., and a curing time of 2-10 h.

[0111] A third aspect of the present invention provides a gas cylinder system with a structural health self-sensing monitoring function, the gas cylinder system comprising a gas cylinder, an electrode sensing unit, an excitation signal control unit, a data acquisition unit, and an image reconstruction unit; wherein, the gas cylinder is the gas cylinder with a structural health self-sensing monitoring function as described in the first aspect.

[0112] According to some embodiments of the present invention, preferably, the electrode sensing unit includes an electrode group and a contralateral electrode group respectively provided at both ends of the gas cylinder;

[0113] The electrodes in the electrode group and the opposite electrode group are connected to the boundary of the smart sensing layer in the gas cylinder through conductive silver paste to collect the boundary voltage of the smart sensing layer.

[0114] According to some embodiments of the present invention, preferably, the number of electrodes in the electrode group is ≥8, and the electrodes are equidistantly distributed.

[0115] According to some embodiments of the present invention, preferably, the number of electrodes in the contralateral electrode group is ≥8, and the electrodes are equidistantly distributed.

[0116] Figure 4 is a schematic diagram of a gas cylinder with structural health self-sensing monitoring function according to a specific embodiment of the present invention. As can be seen from the figure, the gas cylinder includes an inner liner, and a carbon fiber winding layer, a glass fiber insulation layer, an intelligent sensing layer and a glass fiber protective layer are sequentially stacked on the outer surface of the inner liner.

[0117] In addition, an electrode group and an opposite electrode group are provided at both ends of the gas cylinder. The electrodes in the electrode group and the opposite electrode group are connected to the boundary of the smart sensing layer in the gas cylinder through conductive silver paste to collect the boundary voltage of the smart sensing layer.

[0118] The present invention will be described in detail below through examples.

[0119] In the following examples and comparative examples, unless otherwise specified, the raw materials used are all commercially available.

[0120] Polyacrylonitrile-based carbon fibers were purchased from Zhongfu Shenying Carbon Fiber Co., Ltd., with the models / brands being TG800-24K and TG800-12K.

[0121] Triethylenetetramine was purchased from Tianjin Dingshengxin Chemical Co., Ltd.;

[0122] Polyvinylpyrrolidone was purchased from Chengdu Kelong Chemical Reagent Factory;

[0123] Hexadecylpyridine chloride was purchased from Tianjin Xingfu Fine Chemical Research Institute;

[0124] Bisphenol A epoxy resin E-51 was purchased from Shanghai Xinhua Resin Factory;

[0125] The vinyl resin was 430LV vinyl resin purchased from Nanjing Jinling DSM Resins Co., Ltd.

[0126] The methyl ethyl ketone peroxide was Aksu Butanox M50.

[0127] In the following examples and comparative examples, the relevant parameters were measured by the following methods, wherein:

[0128] The thickness of each layer was measured by optical metallographic microscope.

[0129] Example 1

[0130] (1) Preparation of carbon fiber winding layer: Carbon fibers impregnated with resin I and curing agent I are wound around the outer surface of the inner liner to obtain a prefabricated gas cylinder I; wherein:

[0131] The material of the liner is nylon; the wall thickness of the liner is 5mm;

[0132] The carbon fiber is polyacrylonitrile-based carbon fiber with a tow size of 24K;

[0133] Resin I is bisphenol A epoxy resin E-51; curing agent I is triethylenetetramine;

[0134] The weight ratio of carbon fiber to resin I is 1.93:1, wherein the amount of resin I is 21.5 kg;

[0135] The weight ratio of curing agent I to resin I is 0.12:1;

[0136] The winding method is to alternate between hoop winding and spiral winding. First, hoop winding is performed at an angle of 87° (7 layers); then spiral winding is performed at angles of 10° (4 layers), 18° (4 layers), 33° (6 layers), and 45° (6 layers). The total number of winding layers is 27.

[0137] (2) Preparation of glass fiber insulation layer: Winding glass fiber I impregnated with resin II and curing agent II around the outer surface of prefabricated gas cylinder I to obtain prefabricated gas cylinder II; wherein:

[0138] Glass fiber I is E-glass fiber; Resin II is bisphenol A epoxy resin E-51; Curing agent II is triethylenetetramine;

[0139] The weight ratio of glass fiber I to resin II is 1.9:1, wherein the amount of resin II is 11.1 kg;

[0140] The weight ratio of curing agent II to resin II is 0.13:1;

[0141] The winding method is spiral winding, and the spiral winding angles are 13° (3 layers), 20° (3 layers), and 35° (5 layers) in sequence; the total number of winding layers is 11;

[0142] (3) Preparation of the intelligent sensing layer: Few-layer graphene is dispersed in a resin matrix, and the obtained resin mixture is then mixed with a curing agent III to obtain a gel mixture, and the gel mixture is then coated on the outer surface of the prefabricated gas cylinder II to form a coating layer, and then a glass fiber bundle is wound around the outer surface of the coating layer to form a glass fiber bundle layer, and the coating and winding are alternately performed to obtain a prefabricated gas cylinder III; wherein:

[0143] The resin matrix is ​​bisphenol A epoxy resin E-51; the thickness of the few-layer graphene is 4nm and the lateral size is 35μm;

[0144] The amount of the few-layer graphene is 0.85 wt% of the amount of the resin matrix, wherein the amount of the resin matrix is ​​18.2 kg;

[0145] The amount of glass fiber bundle used is 60wt% of the amount of resin matrix used;

[0146] Curing agent III is triethylenetetramine; the amount of curing agent III is 11wt% of the amount of the resin matrix;

[0147] The dispersion step specifically comprises: in the presence of an organic solvent, contacting the few-layer graphene with a dispersant and performing a first-stage ultrasonic treatment to obtain a mixture; drying the resin matrix, contacting the mixture with the resin matrix again and performing a second-stage ultrasonic treatment, and then vacuum drying the obtained dispersion to remove the organic solvent; wherein: the organic solvent is ethanol; the dispersant is polyvinyl pyrrolidone; the amount of the dispersant is 2.3 wt% of the amount of the few-layer graphene; the first-stage ultrasonic treatment time is 30 minutes; the drying time is 30 minutes, and the drying temperature is 110° C.; the second-stage ultrasonic treatment time is 70 minutes; and the vacuum drying conditions are: temperature is 80° C., and time is 60 minutes.

[0148] The winding method is spiral winding with a spiral winding angle of 30 degrees; there are 15 layers of glass fiber bundles, and each layer has the same thickness; the diameter of the spirally wound pole hole is larger than the diameter of the bottle mouth of the gas cylinder; the coating boundary coincides with the position of the wound pole hole;

[0149] (4) Preparation of glass fiber protective layer: Winding glass fiber II impregnated with resin III and curing agent IV around the outer surface of prefabricated gas cylinder III to obtain prefabricated gas cylinder IV; wherein:

[0150] Glass fiber II is S-glass fiber; resin III is bisphenol A epoxy resin E-51; curing agent IV is triethylenetetramine;

[0151] The weight ratio of glass fiber II to resin III is 1.82:1, wherein the amount of resin III is 5.1 kg;

[0152] The weight ratio of curing agent IV to resin III is 0.13:1;

[0153] The winding method is to alternate between hoop winding and spiral winding, first hoop winding with an angle of 87° (2 layers), then spiral winding with angles of 12° (2 layers) and 18° (1 layer). The total number of winding layers is 5.

[0154] The diameter of the polar hole of the spiral winding is smaller than the diameter of the polar hole of the spiral winding in step (3);

[0155] (5) curing the prefabricated gas cylinder IV to obtain a gas cylinder; wherein:

[0156] The curing conditions are as follows: curing temperature is 80°C and curing time is 8 hours.

[0157] In this gas cylinder, the thickness of the carbon fiber winding layer is 16.2mm; the thickness of the glass fiber insulation layer is 5.5mm; the thickness of the intelligent sensing layer is 9mm; and the thickness of the glass fiber protective layer is 2.5mm.

[0158] Example 2

[0159] The method of Example 1 is followed, except that:

[0160] In step (1), the material of the inner liner is high-density polyethylene; the wall thickness of the inner liner is 7 mm and the volume is 350 L;

[0161] The carbon fiber is polyacrylonitrile-based carbon fiber with a tow size of 12K;

[0162] Resin I is vinyl resin; curing agent I is methyl ethyl ketone peroxide;

[0163] The weight ratio of carbon fiber to resin I is 1.81:1, wherein the amount of resin I is 24.6 kg;

[0164] The weight ratio of curing agent I to resin I is 0.04:1;

[0165] The winding method is to alternate between hoop winding and spiral winding. First, hoop winding is performed at an angle of 87° (5 layers); then spiral winding is performed at angles of 10° (5 layers), 16° (5 layers), 28° (5 layers), 41° (5 layers), and 60° (5 layers). The total number of winding layers is 30.

[0166] In step (2): glass fiber I is E-glass fiber;

[0167] Resin II is vinyl resin; curing agent II is methyl ethyl ketone peroxide;

[0168] The weight ratio of glass fiber I to resin II is 1.9:1, wherein the amount of resin II is 14.9 kg;

[0169] The weight ratio of curing agent II to resin II is 0.05:1;

[0170] The winding method is spiral winding, and the spiral winding angles are 12° (5 layers), 20° (5 layers), and 40° (5 layers) in sequence; the total number of winding layers is 15;

[0171] In step (3), the resin matrix is ​​bisphenol A epoxy resin E-51; the thickness of the few-layer graphene is 6 nm and the lateral size is 50 μm; the amount of the few-layer graphene is 3 wt % of the amount of the resin matrix, wherein the amount of the resin matrix is ​​21.9 kg, and the amount of the glass fiber bundle is 60 wt % of the amount of the resin matrix;

[0172] Curing agent III is triethylenetetramine; the amount of curing agent III is 15wt% of the amount of the resin matrix;

[0173] The dispersion step specifically comprises: in the presence of an organic solvent, contacting the few-layer graphene with a dispersant and performing a first-stage ultrasonic treatment to obtain a mixture; drying the resin matrix, contacting the mixture with the resin matrix again and performing a second-stage ultrasonic treatment, and then vacuum drying the obtained dispersion to remove the organic solvent; wherein: the organic solvent is ethanol; the dispersant is polyvinyl pyrrolidone; the amount of the dispersant is 3wt% of the amount of the few-layer graphene; the first-stage ultrasonic treatment time is 60 minutes; the drying time is 60 minutes, and the drying temperature is 80°C; the second-stage ultrasonic treatment time is 90 minutes; and the vacuum drying conditions are: temperature is 60°C, and time is 120 minutes.

[0174] The winding method is spiral winding with a spiral winding angle of 40 degrees; there are 17 layers of glass fiber bundles, and each layer has the same thickness; the diameter of the spirally wound pole hole is larger than the diameter of the bottle mouth of the gas cylinder; the coating boundary coincides with the position of the wound pole hole;

[0175] In step (4): the glass fiber II is an S-glass fiber;

[0176] Resin III is vinyl resin; curing agent IV is methyl ethyl ketone peroxide;

[0177] The weight ratio of glass fiber II to resin III is 2.3:1, wherein the amount of resin III is 5.22 kg;

[0178] The weight ratio of curing agent IV to resin III is 0.05:1;

[0179] The winding method is to alternate between hoop winding and spiral winding, first hoop winding with an angle of 88° (2 layers), then spiral winding with angles of 17° (2 layers) and 30° (2 layers) in sequence; the total number of winding layers is 6;

[0180] The diameter of the polar hole of the spiral winding is smaller than the diameter of the polar hole of the spiral winding in step (3);

[0181] In step (5), the curing conditions are: curing temperature is 150°C, and curing time is 5h;

[0182] The obtained gas cylinder has the same structure as in Example 1, with the carbon fiber winding layer having a thickness of 18 mm, the glass fiber insulation layer having a thickness of 7.5 mm, the intelligent sensing layer having a thickness of 11 mm, and the glass fiber protective layer having a thickness of 3 mm.

[0183] Example 3

[0184] The method of Example 1 is followed, except that in step (3), the amount of the few-layer graphene used is 7 wt % of the amount of the resin matrix used; the rest are the same, to obtain a gas cylinder.

[0185] Example 4

[0186] The method of Example 1 is followed, except that in step (3), hexadecylpyridinium chloride is used as the dispersant; the rest of the steps are the same, to obtain a gas cylinder.

[0187] Table 1

[0188] Table 1 shows the content relationship of the carbon fiber winding layer, glass fiber insulation layer, intelligent sensing layer and glass fiber protective layer of the gas cylinders prepared in Examples 1 to 4.

[0189] Comparative Example 1

[0190] The method of Example 1 is followed, except that step (3) is omitted, and in step (4), glass fiber II impregnated with resin III and curing agent IV is wrapped around the outer surface of prefabricated gas cylinder II. All other aspects remain the same, and the resulting gas cylinder lacks the intelligent sensing layer. Because this gas cylinder lacks the intelligent sensing layer, it is impossible to use electrical resistance tomography technology to achieve real-time structural sensing, damage monitoring, and location of the gas cylinder.

[0191] Comparative Example 2

[0192] The method of Example 1 is followed, except that in step (3), the few-layer graphene is replaced by carbon nanotubes; the rest are the same, to obtain a gas cylinder.

[0193] Test Example 1

[0194] The gas cylinders were prepared according to the methods of the embodiment and the comparative example. After the coating and winding of step (3) were completed, step (3) also included the step of leading out the electrodes, specifically:

[0195] The product obtained by alternately performing the coating and the winding is cured at room temperature for 16 hours. After the surface becomes sticky, the multiple copper foil electrodes in the electrode group and the opposite electrode group are respectively compounded on the boundaries of the smart sensing layer at both ends of the gas cylinder through conductive silver paste to collect the boundary voltage of the smart sensing layer; wherein, the multiple copper foil electrodes in the electrode group and the opposite electrode group are equidistantly distributed, as shown in Figures 5 and 6; the number of electrodes in the electrode group is 8; the number of electrodes in the opposite electrode group is 8.

[0196] The electrode sensing unit, excitation signal control unit, data acquisition unit and image reconstruction unit of the gas cylinder are connected through a computer for data acquisition, as shown in Figure 6. A set of copper foil electrodes at opposite ends of the gas cylinder are used as the injection point and output point of the excitation current signal, and a DC power supply is injected. At the same time, a precision current and voltage signal acquisition instrument is used to measure the voltage difference of each group of remaining adjacent electrode pairs, as shown in Figure 5. This process is repeated when each group of relative electrode pairs is excited in turn. The excitation current is a small current that does not damage the material itself. The voltage value change between the electrodes caused by the structural change of the gas cylinder's intelligent sensing layer is measured. The collected boundary voltage value is combined with a suitable image reconstruction algorithm to reconstruct the conductivity distribution inside the gas cylinder, thereby realizing visual monitoring of the internal structure of the gas cylinder. The specific calculation method refers to the calculation method proposed by Qu Shuxuan et al. (Qu Shuxuan, Gong Wenbin, Sun Xiaozhu, et al. Online damage monitoring of composite materials based on carbon nanotube films [J]. Acta Aeronautica Sinica, 2022, 43(01): 586-598.);

[0197] The test results of the average resistivity and average conductivity of adjacent electrode pairs (i.e., the smart sensing layer) are shown in Table 2:

[0198] Table 2

[0199] Test Example 2

[0200] The mechanical properties and air tightness tests of the gas cylinders prepared in the embodiment and the comparative example were respectively carried out, and the results are shown in Table 3.

[0201] The test method for hydraulic bursting pressure is to conduct hydraulic bursting test at room temperature (25±2℃) in accordance with the test method specified in GB / T 15385;

[0202] The test method for hydrogen leakage rate is as follows: perform an airtightness test at 15±5℃ according to the vacuum chamber method specified in Appendix F of T / CATSI 02 007-2020.

[0203] Table 3

[0204] The above results show that the intelligent sensing layer in the gas cylinder provided by the present invention has a high electrical conductivity. While improving the strength and airtightness of the winding layer, it utilizes its resistance / strain response effect and, with the help of electrical resistance tomography technology, can achieve in-situ, online, and full-life self-sensing structural health monitoring of the gas cylinder without disassembling the gas cylinder, realizing real-time structural perception, damage monitoring, and positioning of the gas cylinder. In combination with the settings of other layers in the gas cylinder, the gas cylinder has excellent mechanical properties and good gas barrier properties.

[0205] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A gas cylinder with structural health self-sensing monitoring function, characterized in that: The gas cylinder comprises an inner liner, and a carbon fiber winding layer, a glass fiber insulation layer, an intelligent sensing layer and a glass fiber protective layer are sequentially stacked on the outer surface of the inner liner; wherein: The carbon fiber winding layer contains carbon fibers and a cured resin I; The glass fiber insulation layer contains glass fiber I and cured resin II; The smart sensing layer contains glass fiber bundles, cured epoxy resin, and few-layer graphene dispersed in the cured epoxy resin; The glass fiber protective layer contains glass fiber II and curing resin III.

2. The gas cylinder according to claim 1, wherein: The material of the liner is metal and / or plastic; the metal is selected from at least one of aluminum alloy, magnesium alloy and titanium alloy; the plastic is at least one of nylon, high-density polyethylene and modified polyethylene; And / or, the wall thickness of the inner liner is 1 mm to 10 mm, and the volume of the inner liner is 3 L to 680 L.

3. The gas cylinder according to claim 1, wherein: The thickness of the carbon fiber winding layer is 4-18 mm; And / or, in the carbon fiber winding layer, the carbon fiber is polyacrylonitrile-based carbon fiber; and the tow size of the polyacrylonitrile-based carbon fiber is 12K to 24K.

4. The gas cylinder according to any one of claims 1 to 3, wherein: In the carbon fiber winding layer, the cured resin I is obtained by curing a mixture containing resin I and curing agent I; the resin I is selected from epoxy resin and / or vinyl resin; the curing agent I is selected from at least one of triethylenetetramine, tertiary amine titanate, modified polyether amine and methyl ethyl ketone peroxide.

5. The gas cylinder according to any one of claims 1 to 3, wherein: The thickness of the glass fiber insulation layer is 4-10 mm; and / or, the glass fiber I is E-glass fiber; In the glass fiber insulation layer, the cured resin II is obtained by curing a mixture containing resin II and curing agent II; the resin II is selected from epoxy resin and / or vinyl resin; the curing agent II is selected from at least one of triethylenetetramine, tertiary amine titanate, modified polyether amine and methyl ethyl ketone peroxide.

6. The gas cylinder according to any one of claims 1 to 3, wherein: The thickness of the intelligent sensing layer is 6 mm to 12 mm; And / or, the few-layer graphene has a thickness of 2-10 nm and a lateral size of 10-50 μm; And / or, based on the total weight of the smart sensing layer, the content of the glass fiber bundle is 54-70wt%, the content of the cured epoxy resin is 27-46wt%, and the content of the few-layer graphene is 0.07-2.5wt%.

7. The gas cylinder according to any one of claims 1 to 3, wherein: In the smart sensing layer, the cured epoxy resin is obtained by curing a mixture containing epoxy resin and curing agent III; the curing agent III is at least one of triethylenetetramine, tertiary amine titanate and modified polyether amine.

8. The gas cylinder according to any one of claims 1 to 3, wherein: The smart sensing layer further contains a dispersant; the dispersant is selected from cetylpyridinium chloride and / or polyvinylpyrrolidone; the content of the dispersant is 2-6.5wt% of the content of the few-layer graphene.

9. The gas cylinder according to any one of claims 1 to 3, wherein: The thickness of the glass fiber protective layer is 2-5 mm; and / or, the glass fiber II is selected from E-glass fiber and / or S-glass fiber; In the glass fiber protective layer, the cured resin III is obtained by curing a mixture containing resin III and curing agent IV; the resin III is selected from epoxy resin and / or vinyl resin; the curing agent IV is selected from at least one of triethylenetetramine, tertiary amine titanate, modified polyether amine and methyl ethyl ketone peroxide.

10. A method for preparing a gas cylinder with a structural health self-sensing monitoring function as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) Preparation of carbon fiber winding layer: Winding carbon fiber impregnated with resin I and curing agent I on the outer surface of the inner liner to obtain a prefabricated gas cylinder I; (2) Preparation of glass fiber insulation layer: Winding glass fiber I impregnated with resin II and curing agent II around the outer surface of the prefabricated gas cylinder I to obtain a prefabricated gas cylinder II; (3) Preparation of the smart sensing layer: coating the outer surface of the prefabricated gas cylinder II with a gel mixture containing a few-layer graphene, epoxy resin and curing agent III to form a coating layer, and then winding a glass fiber bundle on the outer surface of the coating layer to form a glass fiber bundle layer, wherein the coating and the winding are performed alternately to obtain a prefabricated gas cylinder III; (4) Preparation of glass fiber protective layer: Winding glass fiber II impregnated with resin III and curing agent IV on the outer surface of the prefabricated gas cylinder III to obtain a prefabricated gas cylinder IV; (5) The prefabricated gas cylinder IV is subjected to a curing treatment.

11. The method according to claim 10, wherein: The winding method in step (1) is circumferential winding and / or spiral winding, wherein the circumferential winding angle is 85°-90°, and the spiral winding angle is 9°-60°; And / or, the number of layers of winding in step (1) is 6-30 layers; The weight ratio of the carbon fiber to the resin I is 1.81-2.47:1; The weight ratio of the curing agent I to the resin I is 0.03-0.2:

1.

12. The method according to claim 10, wherein: The winding method in step (2) is spiral winding, and the angle of the spiral winding is 12°-40°; And / or, the number of layers of winding in step (2) is 8-20 layers; The weight ratio of the glass fiber I to the resin II is 1.81-2.36:1; The weight ratio of the curing agent II to the resin II is 0.03-0.2:

1.

13. The method according to any one of claims 10 to 12, wherein: The winding method in step (3) is spiral winding, and the angle of the spiral winding is 25°-50°; the diameter of the polar hole of the spiral winding is larger than the diameter of the bottle mouth of the gas cylinder; And / or, the glass fiber bundle layer in step (3) is 10-20 layers; And / or, the coating boundary in step (3) coincides with the position of the wound pole hole.

14. The method according to any one of claims 10 to 12, wherein: In step (3), the amount of the few-layer graphene is 0.2-6wt% of the amount of the epoxy resin; The amount of the curing agent III is 10-30wt% of the amount of the epoxy resin; The preparation method of the gel mixture comprises: dispersing the few-layer graphene in the epoxy resin, and then mixing the obtained resin mixture with the curing agent III.

15. The method according to any one of claims 10 to 12, wherein: In step (4), the winding method is circumferential winding and / or spiral winding, wherein the circumferential winding angle is 85-90°, and the spiral winding angle is 12°-40°; And / or, the number of layers of winding in step (4) is 4-10 layers; The polar hole diameter of the spiral winding in step (4) is smaller than the polar hole diameter of the spiral winding in step (3); the angle of the spiral winding in step (4) is smaller than the angle of the spiral winding in step (3).

16. The method according to any one of claims 10 to 12, wherein: In step (4), the weight ratio of the glass fiber II to the resin III is 1.67-2.36:1; The weight ratio of the curing agent IV to the resin III is 0.03-0.2:1; In step (5), the curing conditions include: curing temperature of 70-180° C. and curing time of 2-10 h.

17. A gas cylinder system with structural health self-sensing monitoring function, characterized in that: The gas cylinder system includes a gas cylinder, an electrode sensing unit, an excitation signal control unit, a data acquisition unit and an image reconstruction unit; wherein the gas cylinder is a gas cylinder with a structural health self-sensing monitoring function as described in any one of claims 1-9.

18. The gas cylinder system according to claim 17, wherein: The electrode sensing unit comprises an electrode group and an opposite electrode group respectively arranged at two ends of the gas cylinder; The electrodes in the electrode group and the opposite electrode group are connected to the boundary of the smart sensing layer in the gas cylinder through conductive silver paste to collect the boundary voltage of the smart sensing layer.

19. The gas cylinder system according to claim 18, wherein: The number of electrodes in the electrode group is ≥ 8, and the electrodes are equidistantly distributed; The number of electrodes in the contralateral electrode group is ≥8, and the electrodes are equidistantly distributed.

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