Large-diameter resin-based composite material high-pressure container and design method thereof

Abstract

The invention relates to the technical field of high-pressure containers for storing liquid or gas, in particular to a large-diameter resin-based composite material high-pressure container and a design method thereof.A preliminary fiber winding composite material pressure container is designed according to the grid theory, and the pressure container is optimally designed through a water pressure bursting test and finite element verification; under the action of a PLC control system, a multi-dimensional winding machine is utilized, a steel inner container serves as a mold, the fiber soaked with the resin solution is wound to the outer wall of the mold, fiber winding tension in the fiber winding annular direction and the fiber winding spiral direction is calculated according to the fiber winding thickness and the fiber winding angle, curing treatment is carried out, and the fiber winding tension in the fiber winding annular direction and the fiber winding spiral direction is obtained. According to the large-diameter resin-based composite material high-pressure container and the manufacturing method thereof, optimization design is conducted on the large-diameter resin-based composite material high-pressure container, the high-quality fiber-reinforced epoxy resin composite material is selected as a base body, and double improvement of strength and light weight is achieved through accurate fiber laying angle and density control.

Description

Technical Field

[0001] The present invention relates to the technical field of high-pressure containers for storing liquids or gases, and particularly to a large-diameter resin-based composite high-pressure container and its design method. Background Art

[0002] The solid structure of a fiber-wound composite pressure vessel is composed of an inner liner layer, a fiber-wound reinforcement layer, and an outer protective layer. In the composite container, the reinforcement layer bears most of the pressure load, and the fiber is the main load-bearing part of the composite material. Currently, commonly used fiber reinforcement materials include glass fiber, carbon fiber, Kevlar fiber, etc., and the main product form is untwisted yarn.

[0003] A composite material winding and forming storage tank is a common form of large-pressure vessels. In the composite material fiber winding and forming process, the tension control during the fiber winding process is an important parameter, which directly affects the quality and performance of the winding products. In related technologies, the forming process of the storage tank is two-dimensional fixed-length winding of the cylinder body, and the fittings such as the head and flange are formed separately. During the winding process of the cylinder body, the yarn tension is not controlled, and the performance of the fiber cannot be fully exerted. Then, the cylinder body is connected to the head, flange, etc. to form a storage tank. This forming process is mainly prone to forming a cylindrical shape, and the tension of each layer cannot be controlled as required, with large process errors, poor pressure resistance, and defects such as dripping in the overall sealing performance. When the shape of the storage tank is complex, it needs to be formed and assembled separately multiple times. The existing technology makes it consume too much energy, which not only increases the manufacturing cost of high-pressure containers but also wastes natural resources excessively.

[0004] In the existing technology, the design of large-diameter high-pressure-resistant containers often faces problems such as insufficient pressure-bearing capacity, excessive weight, and poor fatigue resistance. Traditional design methods have limitations in material selection and winding processes, and it is difficult to meet the high-performance and lightweight requirements of modern industries for high-pressure containers. In recent years, with the development of composite material technology and intelligent manufacturing technology, new ideas have been provided for the design of high-pressure containers. However, there is still a lack of a design method in the current market that can comprehensively improve the performance of the container and control the cost. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned existing technology, the purpose of the present invention is to provide a large-diameter resin-based composite material and its design method. The present invention proposes a unique design method to optimize the design of a large-diameter resin-based composite high-pressure container. This design method selects a high-quality fiber-reinforced epoxy resin composite material as the matrix, and through precise control of the fiber laying angle and density, realizes the dual improvement of strength and lightweight.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A design method for a large-diameter resin-based composite material, comprising the following steps: According to the design conditions and specification requirements of steel-lined filament-wound composite pressure vessels, the structure design of the steel liner is completed. Based on the grid theory, the preliminary winding angle and preliminary fiber winding thickness of the fiber winding layer outside the steel liner are designed to obtain a preliminary fiber-wound composite pressure vessel.

[0007] The bursting pressure of the preliminary fiber-wound composite pressure vessel is obtained through a hydrostatic bursting test. The finite element analysis software is used to numerically simulate the bursting test on the finite element model of the composite pressure vessel. Compare whether the simulated bursting pressure and bursting position are consistent with the results of the hydrostatic bursting test. If they are not consistent, adjust the fiber winding angle and fiber winding thickness of the preliminary fiber-wound composite pressure vessel until the simulation results match the hydrostatic bursting test results. If they are consistent, optimize the structure of the verified preliminary fiber-wound composite pressure vessel.

[0008] The structure optimization method includes the following steps: Apply different internal pressures to the verified preliminary fiber-wound composite pressure vessel, and screen and optimize the pressure vessels prepared with different fiber winding angles and fiber winding thicknesses. Under the bursting mode at a safe position that meets the design requirements and specification requirements, obtain the optimized fiber winding angle and fiber winding thickness, and conduct finite element verification.

[0009] Calculate the fiber winding tensions in the circumferential and helical directions of the fiber winding based on the fiber winding angle and fiber winding thickness obtained through structure optimization; According to the obtained fiber winding angle, fiber winding thickness, and fiber winding tension data in the circumferential and helical directions of the fiber winding, under the action of the PLC control system, use a multi-dimensional winding machine with the steel metal inner liner as the mold to wind the fiber filaments impregnated with the resin solution onto the outer wall of the mold. The winding layer is wound from the inside out in a way that the winding tension gradient decreases, and then through curing treatment, a large-diameter resin-based composite high-pressure vessel is obtained.

[0010] In a preferred embodiment of the present invention, the calculation formulas for the fiber winding tensions in the circumferential and helical directions of the fiber winding are: ; where T is the fiber winding layer tension in the circumferential and helical directions of the fiber winding; t f is the fiber winding thickness, with the unit of mm; A is the cross-sectional area of each fiber strand, with the unit of mm 2 ; E 0 is the elastic modulus of the inner liner, with the unit of MPa; t 0 is the thickness of the inner liner, with the unit of mm; E f is the elastic modulus of the fiber layer, with the unit of MPa; β is the balance factor, and α is the fiber winding angle, with the unit of °.

[0011] In a preferred embodiment of the present invention, the number of winding layers can be calculated as follows: N = V f ×P f ×δ×B / Y×10 5 ; Where N is the number of winding layers, V f is the fiber volume percentage, P f is the fiber density, in g / cm 3 , δ is the fiber winding thickness, in cm, B is the yarn sheet width, in cm, and Y is the linear density at the guide wire head, in g / km.

[0012] Calculation of fiber winding angle, spiral and annular fiber winding thickness: tanα=(r 1 +r 2 ) / D, Hα=(RP-2β 1 t) / (2β 1 cos 2 α), Hθ=[(2-tan 2 α)RP-2(1-tan2α)β 1 t] / 2β 1 , Hα is the helical fiber winding thickness, in mm, Hθ is the annular fiber winding thickness, in mm, r 1 and r 2 are the radii of the front and rear pole holes, in mm, D is the length of the barrel, in mm, R is the radius of the barrel, in mm, P is the blasting pressure, in MPa, β 1 is the ultimate strength, in MPa, and t is the lining wall thickness, in mm.

[0013] The fiber-wound composite pressure vessel structure designed by the present invention ingeniously integrates the inner liner, the fiber-wound reinforcement layer and the outer protective layer to form an efficient and stable pressure bearing system. The core of this structure is its reinforcement layer, which is constructed through precise fiber winding technology, which not only significantly improves the overall strength of the container, but also ensures that it can withstand and disperse most of the pressure load, thus achieving the ultimate pursuit of safety under extreme working conditions.

[0014] The steel liner was optimized, and the optimized design of the lining structure was completed through fine mechanical analysis and calculation. This process not only takes into account the physical and mechanical properties of the material itself, but also incorporates the stress distribution characteristics of the pressure vessel under different working conditions, ensuring that the lining structure can effectively bear the internal pressure, adapt to changes in the external environment, and maintain long-term stable operation.

[0015] In the design of the winding layer, grid theory is introduced as the core guiding principle. Through precise calculation and simulation of the winding angle, the preliminary optimal winding angle is determined, which can maximize the load-bearing efficiency of the fiber layer while reducing the potential risk of damage caused by stress concentration. In addition, based on the in-depth study of the impact of different winding layer thicknesses on the overall performance of the pressure vessel, this method further refines the design parameters of the winding layer thickness to ensure that each layer of fiber can perform at its best and together form a strong and efficient composite structure.

[0016] In a preferred embodiment of the present invention, the fiber winding method is spiral and annular alternating winding, the winding angle is 5°~90°, and the winding thickness is about ≥2 mm.

[0017] In a preferred embodiment of the present invention, the resin solution is a two-component epoxy resin solution, in which the mass ratio of the epoxy resin to the curing agent is 1:0.2-1.

[0018] In a preferred embodiment of the present invention, the fiber filaments include glass fiber, S high-strength fiber, carbon fiber or basalt fiber.

[0019] In a preferred embodiment of the present invention, the volume percentage of the fiber filaments in the resin solution is 60% to 65%.

[0020] In a preferred embodiment of the present invention, the curing temperature is between 60° C. and 150° C., and the curing time is between 60 min and 180 min.

[0021] The curing process is layered curing. First, a certain thickness of winding layer is formed on the lining, and then it is cured and cooled to room temperature. Then the surface is polished and sprayed with glue, and the second layer is wound, and so on, until the strength and number of winding layers required by the design are reached.

[0022] In a preferred embodiment of the present invention, the inner lining layer includes a flange, a pole hole, a head and a cylinder. The inner lining layer can be used as a mold used in the molding process of a large pressure vessel. A large pressure vessel refers to a pressure vessel with a metal liner and fully wrapped with fibers. Metal lining layers are the first choice for pressure vessel liners due to their own advantages such as high strength, not easy to deform, mature molding process, and the ability of the container to ensure airtightness. However, because they are denser than composite materials, they are heavier, difficult to transport, and have high costs. Their specific strength and specific modulus are inferior to those of composite materials. Therefore, the composite material container formed by winding the outer wall of the metal liner takes into account both performances. In order to improve the strength of the pressure vessel, the outer surface of the liner is spirally and circumferentially wound to improve the load-bearing capacity of the pressure vessel.

[0023] In a preferred embodiment of the present invention, the cylinder body utilizes helical winding and annular winding fibers, and the end cap utilizes helical winding fibers.

[0024] Another object of the present invention is to provide a large-diameter resin matrix composite high-pressure vessel obtained by the design method described in any one of the above. The high-pressure vessel is composed of three parts: a liner layer, a fiber-wound reinforcement layer, and an outer protective layer. The liner layer is a steel metal inner liner, and the outer protective layer is a UV coating.

[0025] In a preferred embodiment of the present invention, the diameter of the high-pressure vessel is ≥2000 mm, the design pressure is 6.9 Mpa to 20 Mpa, the hydrostatic test strength is 10 Mpa to 30 Mpa, and the pressure-resistant burst strength is 17 Mpa to 50 Mpa.

[0026] The composite fiber-wound high-pressure vessel of the present invention is a specific type of pressure vessel, namely, a type I composite pressure vessel, which is designed by combining the manufacture of a metal inner liner and a fiber-wound layer. The metal inner liner is an ideal choice for the inner liner of such vessels due to its advantages in strength, anti-deformation ability, mature forming process, and good sealing performance. However, the inherent high-density characteristic of the metal material also leads to problems such as large weight, inconvenient transportation, and relatively high cost, and it cannot be compared with composites in terms of specific strength and specific modulus.

[0027] Compared with the prior art, the beneficial effects of the present invention are: 11. The design method of a large-diameter resin-based composite high-pressure vessel provided by the present invention adopts a method combining theory, experiment and finite element simulation to perform structural optimization design on the bursting pressure and stress performance of the fiber-wound composite pressure vessel, calculates the fiber winding layer tension in the circumferential and spiral directions of the fiber winding through the fiber winding angle and fiber winding thickness after structural optimization, adopts optimized tension control and a tension control system with regular layer-by-layer decrease between layers, thus changing the previous situation of fiber-wound large-diameter pressure vessels without tension control. This tension control system can increase the compressive strength of large-diameter pressure vessels by 15% to 35%, and the bursting pressure of pressure vessels by 25% to 50%. Finally, under the action of a PLC control system, a multi-dimensional winding machine is used with a steel inner liner as a mold to wind the fiber filaments soaked in the resin solution onto the outer wall of the mold, and then undergoes a curing treatment to obtain a large-diameter resin-based composite high-pressure vessel. The present invention adopts a ply structure of spiral and circumferential "alternating" fiber winding, which changes the previous ply structure of "centralized" fiber winding, improves the compressive strength of the pressure vessel by 25% to 45%, and improves the bursting pressure of the pressure vessel by 35% to 50%. The multifunctional glue dipping machine controlled by PLC strictly controls the glue content of the fiber, which changes the previous situation of unstable, uneven and irregular glue mixing ratio. By using the multifunctional glue dipping machine, the glue mixing process can be achieved without bubble generation, the porosity of the structural layer is reduced, and the compressive strength of the large-diameter pressure vessel is increased by 5% to 10%, and the bursting pressure of the pressure vessel is increased by 15% to 25%. The curing treatment process adopted by the present invention always maintains the initial stress of the pressure vessel and combines it with regular tension control, solves the phenomenon of bubbles, floating glue, glue nodules and the like on the surface of the pressure vessel in the past, and improves the compressive strength of the large-diameter pressure vessel by 15% to 25%, and the bursting pressure of the pressure vessel is increased by 25% to 35%.

[0028] 2. The fiber-wound composite pressure vessel structure designed by the present invention ingeniously integrates the inner liner, the fiber-wound reinforcement layer and the outer protective layer, together forming an efficient and stable pressure bearing system. The core of this structure lies in its reinforcement layer, which is constructed through precise fiber winding technology, which not only significantly improves the overall strength of the container, but also ensures that it can withstand and disperse most of the pressure load, thereby achieving the ultimate pursuit of safety under extreme working conditions.

[0029] 3. The present invention proposes a unique design method for optimizing the design of large-diameter resin-based composite high-pressure vessels. This method uses high-quality fiber-reinforced epoxy resin composite materials as the matrix, and achieves a dual improvement in strength and lightness through precise fiber laying angle and density control. At the same time, the selection of the resin matrix is ​​also strictly screened to ensure that it has excellent heat resistance, chemical corrosion resistance and good processability to adapt to high pressure, high temperature and complex chemical environments.

[0030] 4. In the past, composite pressure vessels had the problems of heavy weight, low strength, poor corrosion resistance, and poor safety. The composite pressure vessels processed by using the design method of the present invention not only take into account the good processability, high strength, and high toughness of the metal liner, but also integrate the advantages of the composite material such as light weight, good safety, and good designability, making it have excellent properties such as good strength and light weight. The weight of the composite pressure vessel can be reduced by 1 / 3 - 2 / 3 compared with that of the steel pressure vessel; at the same time, when the composite material is damaged by impact or high-speed impact, no dangerous fragments will be generated, thereby reducing or avoiding the harm to personnel, and the composite container has better use safety than the metal container.

[0031] 5. The present invention proposes an innovative design method for large-diameter resin-based composite material wound high-pressure vessels, which integrates the essence of advanced material science and precision manufacturing technology, aiming to meet the urgent needs of core industries such as aerospace, medicine, chemical engineering, and energy storage for high-performance and lightweight pressure vessels. Brief Description of the Drawings

[0032] Figure 1 It is the external shape structure of the composite material fiber wound high-pressure vessel.

[0033] Figure 2 It is the schematic diagram of the head of the high-pressure vessel. Detailed Embodiment

[0034] The following combines the embodiments of the present invention, and uses the preferred embodiments and the accompanying drawings to cooperate with a detailed description to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that all the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the following embodiments of the present invention can be obtained through the market or prepared by existing methods.

[0036] The present invention uses a method combining theory, experiment, and finite element simulation to optimize the design of the burst pressure and mechanical properties of the fiber wound composite pressure vessel, and the "theoretical design - experiment combined with finite element verification - structural optimization" closed-loop design method for the fiber wound composite pressure vessel. The external shape structure of the composite material fiber wound high-pressure vessel is as Figure 1As shown in the figure, the specific design method is as follows: According to the design conditions and specification requirements of the steel inner liner fiber-wound composite pressure vessel, the steel inner liner is designed. Based on the grid theory, the preliminary winding angle and the thickness of the preliminary fiber winding layer required for the steel inner liner are designed to obtain a preliminary fiber-wound composite pressure vessel. The bursting pressure of the preliminary fiber-wound composite pressure vessel is obtained through a hydrostatic bursting test. The finite element analysis software is used to numerically simulate the bursting test on the finite element model of the symmetric composite pressure vessel, and compare whether the simulated bursting pressure and bursting position are consistent with the results of the hydrostatic bursting test. If they are not consistent, the structure of the composite pressure vessel designed according to the grid theory is adjusted until the simulation results are consistent with the hydrostatic bursting test results. If they are consistent, the structure of the preliminary fiber-wound composite pressure vessel designed theoretically is optimized. The structure optimization method is to apply different internal pressures to the preliminary fiber-wound composite pressure vessel designed theoretically. To achieve the bursting mode at a safe position that meets the design requirements and specification requirements, the fiber winding layer angle and the fiber winding thickness are optimized structurally, and finite element verification is carried out. The fiber winding tensions in the circumferential and helical directions of the fiber winding are calculated through the fiber winding thickness and fiber winding angle after structure optimization, and the strength of the composite pressure vessel is improved through tension control. Finally, under the action of the PLC control system, using the steel inner liner as a mold, the fiber filaments impregnated with the resin solution are wound around the outer wall of the mold, and then through curing treatment, a large-diameter resin-based composite high-pressure vessel is obtained.

[0037] First, based on the rigorous pressure vessel film theory, this method completes the design of the steel liner structure according to the design conditions and specification requirements of the steel liner fiber-wound composite pressure vessel. This process not only takes into account the physical and mechanical properties of the material itself, but also incorporates the stress distribution characteristics of the pressure vessel under different working conditions, ensuring that the lining structure can effectively bear the internal pressure and adapt to changes in the external environment to maintain long-term stable operation. In the design of the fiber winding layer, this method innovatively introduces the grid theory as the core guiding principle. Through the precise calculation and simulation of the winding angle, the preliminary winding angle is determined, which can maximize the load-bearing efficiency of the fiber layer while reducing the potential damage risk caused by stress concentration. In addition, based on the in-depth study of the influence of different winding layer thicknesses on the overall performance of the pressure vessel, this method further refines the design parameters of the winding layer thickness to ensure that each layer of fiber can play its best performance and together form a strong and efficient composite structure. The core of this design method is to select high-quality resin-based composite materials, such as carbon fiber reinforced epoxy resin composite materials. This material can effectively reduce the weight of the container while ensuring strength through precise fiber laying angle and density control. In addition, the selection of the resin matrix is ​​also crucial. It must have good heat resistance, chemical corrosion resistance and good processability to ensure stable performance under high pressure, high temperature and complex chemical environments. Fiber, as a key load-bearing element in composite materials, plays an irreplaceable role in the reinforcement layer with its excellent mechanical properties and designability. Through carefully selected fiber types, optimized winding angles and density distribution, this structure can adapt to different pressure environments, ensure effective transmission and dispersion of pressure, and minimize the occurrence of stress concentration.

[0038] In addition, the inner liner, as the internal barrier of the container, not only provides the necessary sealing, but also protects the internal medium from the influence of the external environment; while the outer protective layer further enhances the corrosion resistance and wear resistance of the container, extending the service life of the container. The inner liner, the fiber winding reinforcement layer and the outer protective layer complement each other and together constitute this efficient and reliable fiber winding composite pressure vessel entity structure, bringing a new solution to the application of pressure vessels in the industrial field.

[0039] Winding is one of the key technologies for manufacturing large-diameter resin-based composite high-pressure vessels. This technology uses computer-controlled automated winding equipment to wind pre-impregnated composite tows on the liner according to a preset path and tension, and then undergoes a curing process to form an integral structure with continuous fiber reinforcement. This structure can give full play to the load-bearing capacity of the fiber and significantly improve the bursting pressure and fatigue resistance of the container.

[0040] Example 1 A design method for a large-diameter resin matrix composite high-pressure vessel, comprising the following steps: Step 1: Design a steel inner liner according to the design conditions and specification requirements of a fiber-wound composite pressure vessel with a steel inner liner. According to the grid theory, design the preliminary winding angle and preliminary winding thickness of the fiber winding layer on the outer side of the steel inner liner to obtain a preliminary fiber-wound composite pressure vessel.

[0041] The design of the fiber thickness of the helical winding plus circumferential winding on the cylinder can be calculated by the following formula: The fiber thickness t of the helical winding on the cylinder fα , with the unit of mm; ; where: R 1 is the inner radius of the cylinder, with the unit of mm; P b is the designed burst pressure, with the unit of MPa. Generally, P b =n·P w , n is the safety factor, n is between 2.5 and 3, and P w is the working pressure, with the unit of MPa; K is the volume fraction of the helical fiber. Among them, for a low helix angle ≤ 25°, for a large diameter, large tension, and high resin viscosity, it is 0.65; for a large helix angle > 25°, for high tension, small diameter, and low resin viscosity, it is 0.45; is the tensile strength of the longitudinal or circumferential winding fiber during the burst of the shell, that is, the ultimate stress of the fiber; α is the helical winding angle, α is between 5° and 80°, and α is given by the design.

[0042] The fiber thickness t of the circumferential winding on the cylinder fθ , with the unit of mm; the calculation formula is: .

[0043] The required thickness t of the winding fiber f1 , with the unit of mm; the calculation formula is: t f1 =t fα +t fθ ; The actual thickness t of the fiber layer 1 : t 1 ≥t f1 .

[0044] The fiber thickness t of the helical winding on the head f2 , with the unit of mm; ; where: R 2 is the inner radius at the equatorial circle of the head or spherical shell, with the unit of mm; r 0 is the inner radius of the upper polar hole on the head, with the unit of mm; r is the radius of the latitude circle at any position on the head, with the unit of mm.

[0045] The actual thickness t of the winding fiber on the head 2 , with the unit of mm; t2 ≥t f2 。

[0046] Discussion: (1)t fα The thickness at the junction of the helically wound head and the shell is equal to the helically wound thickness of the shell. From the above formula for the helically wound fiber thickness t of the head f2 it can be seen that: at the equatorial circle r = R, the fiber thickness on the head is equal to the helically wound fiber thickness t of the shell fα ; as the radius r of the parallel circle of the latitude decreases, the fiber thickness t f2 increases. At the edge of the polar hole r = r 0 , the fiber thickness t f2 is theoretically infinite, that is, t f2 →∞, which indicates that fiber accumulation occurs at the edge of the polar hole.

[0047] (2)The fibers on the head are helically wound. The helical winding angle α of the fibers wound on the head is variable and can be expressed by a certain function α = α(r) of the radius r on the parallel circle of the latitude. The winding angle at the equatorial circle is α 0 , α 0 is equal to the helical winding angle α. At the edge of the polar hole, the fiber is tangent to the polar hole, so the winding angle α = 90°.

[0048] (3)The total amount of fibers passing through each parallel circle on the latitude is equal to the total amount of fibers passing through the equatorial circle and is equal to the total amount of helically wound fibers passing through the circumferential line on the shell. Since the radius of the parallel circle on the latitude is variable, the fiber thickness of the head is also variable and can be expressed by t f2 = t f2 (r).

[0049] (4)The schematic diagram of the vessel head is as Figure 2 shown.

[0050] Reinforcement of vessel openings Calculation of the reinforcement area of the reinforcing ring: The reinforcement area A of the internally pressurized vessel opening t , with the unit of mm 2 ; A t = d 0 t f2 ; In the formula: d 0 is the opening diameter, with the unit of mm; t f2 is the calculated thickness of the helically wound fibers of the head, with the unit of mm.

[0051] Reinforcement range B of the reinforcing ring t , with the unit of mm; Range of the increased thickness: Measured parallel to the vessel wall and having the same length from the outer edge of the structural opening, B = the length of the outer edge of the opening, that is, B t=d 0 。

[0052] Effective reinforcement area A of the cylinder wall reinforcement ring 1 , in mm 2 ; A 1 = (t - t r ) d 0 ; In the formula: t is the actual thickness of the container wall of the reinforcing material. Among them, for the cylinder, t = t 1 , for the head, t = t 2 , in mm; t r is the fiber thickness required for the cylinder wall. Among them, for the cylinder, t r = t f1 , for the head, t r = t f2 ; d 0 is the opening diameter, in mm;

[0053] Note: If the strength of the reinforcing material is lower than that of the container wall material, the reinforcement area should be increased, and it should be increased in inverse proportion to the strength ratio of the two materials. ; In the formula: is the increased reinforcement area, in mm 2 ; A 1 is the reinforcement area, in mm 2 ; is the tensile strength of the head winding fiber material, in MPa; is the tensile strength of the reinforcing material, in MPa.

[0054] Open hole reinforcement check: A 1 ≥ A t 。

[0055] Open hole reinforcement on the polar hole of the head Reinforcement area calculation of the reinforcement ring: The reinforcement area A of the open hole in the head under internal pressure f , in mm 2 ; A f = d 0 t f3 ; In the formula: d 0 is the opening diameter, in mm; t f3 is the calculated thickness of the head winding fiber, in mm. Since the calculated thickness of the head winding fiber is variable, at the polar hole, r = r 0 , the fiber calculated thickness is infinite ∞. Therefore, the winding fiber thickness on the polar hole of the elliptical head can be estimated by the following formula: ; In the formula: P is the design pressure, in MPa; R is the inner radius of the connection between the head and the cylinder, in mm; S is the design stress, S = 1 / 6 。

[0056] Reinforcement range B of the reinforcement ring f , in mm; Reinforcement thickness range: Measured parallel to the vessel wall, with equal lengths from the outer edge of the structural opening, i.e., B f = d 0 .

[0057] Effective reinforcement area A of the reinforcement ring on the head 2 , and the calculation formula is A 2 = (t - t r )d 0 ; where: A 2 is the effective reinforcement area of the vessel, in mm 2 ; t is the actual thickness of the reinforcement material of the head, in mm; t r is the required reinforcement thickness of the head (t r = t f3 ), in mm; d 0 is the opening diameter, in mm.

[0058] Reinforcement check for the opening: A 2 ≥ A f ; Note: Since the strength of the reinforcement material on the head is low, the reinforcement area should be increased, and it is increased in inverse proportion to the strength ratio of the two materials, ; where: is the increased reinforcement area, in mm 2 ; is the reinforcement area, in mm 2 ; is the tensile strength of the winding fiber material of the head, in MPa; is the tensile strength of the reinforcement material, in MPa.

[0059] Step 2: Obtain the bursting pressure of the preliminary fiber-wound composite pressure vessel through a hydrostatic bursting test, and numerically simulate the bursting test using the finite element analysis software ABAQUS for the finite element model of the symmetric composite pressure vessel. The Hashin failure criterion was introduced to simulate the progressive damage characteristics of the composite material during the pressurization process. The bursting pressure value and bursting location were predicted through progressive damage analysis, and it was found that the bursting pressure and bursting location obtained from the finite element simulation were in good agreement with the test results. Then, structural optimization was carried out on the verified preliminary fiber-wound composite pressure vessel.

[0060] Step 3: The structure optimization method includes the following steps: Apply different internal pressures to the verified preliminary fiber-wound composite pressure vessel, screen and optimize the pressure vessels prepared under different fiber winding angles and fiber winding thicknesses, and obtain the optimized fiber winding angle and fiber winding thickness under the blasting mode at a safe position that meets the design requirements and specification requirements, and conduct finite element verification.

[0061] Calculate the fiber winding tensions in the circumferential and helical directions of the fiber winding based on the fiber winding angle and fiber winding thickness obtained through structure optimization.

[0062] The design of the winding layer number can be calculated by the following formula: N = V f × P f × δ × B / Y × 10 5 ; where, N is the winding layer number; V f is the fiber volume percentage; P f is the fiber density, with the unit of g / cm 3 ; δ is the winding layer thickness, with the unit of cm; B is the width of the yarn sheet, with the unit of cm; Y is the linear density at the wire guide head, with the unit of g / km.

[0063] Calculation of the fiber winding angle, helical and circumferential fiber winding thickness: tanα = (r 1 + r 2 ) / D, Hα = (RP - 2β 1 t) / (2β 1 cos 2 α), Hθ = [(2 - tan 2 α)RP - 2(1 - tan2α)β 1 t] / 2β 1 , Hα is the helical fiber thickness, with the unit of mm, Hθ is the circumferential fiber thickness, with the unit of mm, r 1 and r 2 are the radii of the front and rear polar holes respectively, with the unit of mm, D is the cylinder body length, with the unit of mm, R is the radius of the cylinder body, with the unit of mm, P is the bursting pressure, with the unit of MPa, β 1 is the ultimate strength, with the unit of MPa, t is the inner liner wall thickness, with the unit of mm.

[0064] Calculation of the fiber winding stress balance coefficient: where, Ks = 1 / cos 2 α - β 2 ; Ks is the stress balance coefficient; α is the fiber winding angle; β 2 is the balance factor.

[0065] Calculation of the fiber winding tangent point: θ n-k = (K / n + M) × 360° ± △θ / n; where, θ n-kis the central angle through which the mandrel rotates when winding from the tangent point at the polar hole circumference to the adjacent tangent point n - k in time sequence; K is the k initial tangent points adjacent in time sequence in the winding law of the n - tangent line type; n represents the number of tangent points of the line type; M represents an integer multiple of 360° through which the mandrel rotates when winding from the initial tangent point n to n + 1.

[0066] Calculation of the fiber winding tension in the circumferential and helical directions of fiber winding: ; where T is the fiber winding tension in the circumferential and helical directions of fiber winding; t f is the fiber winding thickness, with the unit of mm; A is the cross - sectional area of each fiber strand, with the unit of mm 2 ; E 0 is the elastic modulus of the inner liner, with the unit of MPa; t 0 is the thickness of the inner liner, with the unit of mm; E f is the elastic modulus of the fiber layer, with the unit of MPa; α is the fiber winding angle, with the unit of °.

[0067] Step 4: According to the obtained data of the fiber winding angle, fiber winding thickness, and fiber winding tension in the circumferential and helical directions of fiber winding, under the action of the PLC control system, using a multi - dimensional winding machine with a steel inner liner as the basis, wind the fiber filaments infiltrated with the resin solution onto the outer wall of the steel inner liner. The winding layer is wound from the inside out in a way that the winding tension decreases in a gradient. Then, through the curing process, a monolithic structure with continuous fiber reinforcement is formed. The curing temperature is 100 °C and the curing time is 60 min. Among them, the volume ratio of the fiber filaments in the resin solution is 65%. The curing process is hierarchical curing. First, wind a winding layer with a certain thickness on the inner liner and then cure it. After cooling to room temperature, sand the surface and spray glue, then wind the second layer, and so on, until the required strength and number of winding layers in the design are reached, obtaining a large - diameter resin - based composite high - pressure vessel.

[0068] The present invention adopts a ply structure of "alternating" helical and circumferential fiber winding, which changes the previous ply structure of "concentrated" fiber winding, and improves the compressive strength of the pressure vessel by 25% - 45%. The burst pressure of the pressure vessel is increased by 35% - 50%.

[0069] Adopting an optimized tension control system and a tension control system with a regular layer - by - layer decreasing tension between layers, it changes the previous situation of no tension control in the fiber winding of large - diameter pressure vessels. Through this tension control system, the compressive strength of large - diameter pressure vessels can be increased by 15% - 35%, and the burst pressure of the pressure vessel is increased by 25% - 50%.

[0070] The PLC is used to control the multi-functional dipping machine to strictly control the gum content of the fiber, changing the previous situation of inconsistent, uneven and non-standard mixing ratios. By using the multi-functional dipping machine, no bubbles are generated during the mixing process, the porosity of the structural layer is reduced, the compressive strength of large-diameter pressure vessels is increased by 5% - 10%, and the burst pressure of the pressure vessels is increased by 15% - 25%.

[0071] The multi-curing process is adopted to always combine the initial stress of the pressure vessel with regular tension control, solving the previous problems such as bubbles, floating gum, and gum tumors on the surface of the pressure vessel. The compressive strength of large-diameter pressure vessels is increased by 15% - 25%, and the burst pressure of the pressure vessels is increased by 25% - 35%.

[0072] Application Areas In the aerospace field, this large-diameter resin matrix composite material wound high-pressure vessel can be used to manufacture key components such as liquid oxygen / liquid hydrogen storage tanks and high-pressure gas cylinders, significantly improving the load capacity and endurance of aircraft. Its lightweight characteristics help reduce fuel consumption and lower launch costs, which is of great significance for promoting the development of frontier fields such as space tourism and deep space exploration.

[0073] In the medical field, this type of container can be used to store medical gases such as high-pressure oxygen and nitrogen, providing a stable and reliable gas supply for medical processes such as intensive care and surgical anesthesia. In the chemical industry, it can be applied to the manufacture of equipment such as high-pressure reaction kettles and gas separation devices, improving production efficiency and reducing safety risks.

[0074] With the rapid development of the new energy industry, energy storage technology has become the key to solving the contradiction between energy supply and demand. This high-pressure vessel can be used to construct new energy storage systems such as compressed air energy storage and flow batteries, providing strong support for power grid peak shaving and distributed energy access.

[0075] It should be noted that when the present invention involves numerical ranges, it should be understood that any value between the two endpoints of each numerical range and the two endpoints can be selected. Since the adopted step methods are the same as the implementation examples, in order to prevent repetition, the present invention describes the preferred implementation examples. Although the preferred implementation examples of the present invention have been described, those skilled in the art can make additional changes and modifications to these examples once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred implementation examples and all changes and modifications falling within the scope of the present invention.

[0076] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A design method for a large-diameter resin-based composite high-pressure vessel, characterized in that: The following steps are involved: According to the design conditions and specification requirements of the steel liner fiber-wound composite pressure vessel, the steel liner is designed, and according to the grid theory, the preliminary fiber winding angle and preliminary fiber winding thickness of the fiber winding layer outside the steel liner are designed to obtain a preliminary fiber-wound composite pressure vessel; The bursting pressure of the preliminary fiber-wound composite pressure vessel is obtained through a water pressure bursting test, and the bursting test is numerically simulated using a finite element model of a symmetrical composite pressure vessel using finite element analysis software, and the simulated bursting pressure and bursting position are compared with the results of the water pressure bursting test to see if they are consistent. If not, the fiber winding angle and fiber winding thickness of the preliminary fiber-wound composite pressure vessel are adjusted until the simulation results match the results of the water pressure bursting test. If they are consistent, the structure of the verified preliminary fiber-wound composite pressure vessel is optimized; The structural optimization method comprises the following steps: applying different internal pressures to the verified preliminary fiber-wound composite pressure vessel, and screening and optimizing the pressure vessels prepared under different fiber winding angles and fiber winding thicknesses, obtaining the optimized fiber winding angle and fiber winding thickness under a safe position blasting mode that meets the design requirements and specification requirements, and performing finite element verification; The fiber winding tension in the circumferential and helical directions of the fiber winding is calculated by using the fiber winding angle and fiber winding thickness obtained by structural optimization; According to the obtained fiber winding angle, fiber winding thickness, fiber winding tension data in the circumferential direction and spiral direction, under the action of the PLC control system, a multi-dimensional winding machine is used with a steel inner liner as a mold to wind the fiber filaments soaked in resin solution onto the outer wall of the mold, and then after curing treatment, a large-diameter resin-based composite high-pressure container is obtained.

2. The design method of a large-diameter resin-based composite high-pressure container according to claim 1, characterized in that: The calculation formula for the fiber winding tension in the hoop and spiral directions is: ； Where T is the fiber winding tension in the hoop and spiral directions; t f is the fiber winding thickness, in mm; A is the cross-sectional area of ​​each fiber, in mm 2 ; E0 is the elastic modulus of the lining, in MPa; t0 is the thickness of the lining, in mm; E f is the elastic modulus of the fiber layer, in MPa; β is the balance factor, and α is the fiber winding angle, in degrees.

3. The design method of a large-diameter resin-based composite high-pressure container according to claim 2, characterized in that: The number of winding layers can be calculated as follows: N=V f ×P f ×δ×B / Y×10 5 ; Where N is the number of winding layers, V f is the fiber volume percentage, P f is the fiber density, in g / cm 3 , δ is the fiber winding thickness, in cm, B is the yarn sheet width, in cm, and Y is the linear density at the guide wire head, in g / km; Calculation of fiber winding angle, spiral and annular fiber winding thickness: tanα=(r1+r2) / D, Hα=(RP-2β1t) / (2β1cos 2 α), Hθ=[(2-tan 2 α)RP-2(1-tan2α)β1t] / 2β1, Hα is the spiral fiber winding thickness, in mm, Hθ is the annular fiber winding thickness, in mm, r1 and r2 are the radii of the front and rear pole holes, respectively, in mm, D is the length of the cylinder, in mm, R is the radius of the cylinder, in mm, P is the blasting pressure, in MPa, β1 is the ultimate strength, in MPa, and t is the lining wall thickness, in mm.

4. The design method of a large-diameter resin-based composite high-pressure container according to claim 1, characterized in that: The fiber winding method is spiral and annular alternating winding, the winding angle is 5°~90°, and the winding layer thickness is ≥2 mm.

5. The design method of a large-diameter resin-based composite high-pressure container according to claim 1, characterized in that: The resin solution is a two-component epoxy resin solution, in which the mass ratio of the epoxy resin to the curing agent is 1:0.2-1.

6. The design method of a large-diameter resin-based composite high-pressure container according to claim 1, characterized in that: The volume percentage of the fiber filaments in the resin solution is 60% to 65%.

7. The design method of a large-diameter resin-based composite high-pressure container according to claim 1, characterized in that: The fiber filaments include glass fiber, S high-strength fiber, carbon fiber or basalt fiber.

8. The design method of a large-diameter resin-based composite high-pressure container according to claim 1, characterized in that: The curing process is layered curing, the curing temperature is 60℃~150℃, and the curing time is 60 min~180 min.

9. A large-diameter resin-based composite high-pressure vessel designed by the design method according to any one of claims 1 to 8, characterized in that: The high-pressure container consists of three parts: an inner lining layer, a fiber-wound reinforcement layer and an outer protective layer.

10. The large-diameter resin-based composite high-pressure container according to claim 9, characterized in that: The diameter of the high-pressure vessel is ≥2000 mm, the design pressure is 6.9 Mpa~20 Mpa, the water pressure test strength is 10 Mpa~30 Mpa, and the pressure bursting strength is 17 Mpa~50 Mpa.

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