A structural optimization method for composite hydrogen storage bottle

Abstract

The present invention discloses a method for optimizing the structure of a composite hydrogen storage bottle, comprising: obtaining mechanical performance parameters of the hydrogen storage bottle, wherein the mechanical performance parameters include elastic modulus and shear modulus; inputting the mechanical performance parameters into a pre-constructed progressive damage model, adjusting the mechanical performance parameters through an environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, and simulating the damage evolution of the hydrogen storage bottle under different use conditions to obtain the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle; based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, designing the structural parameters of the hydrogen storage bottle, wherein the structural parameters include wall thickness, number of layers n and fiber angle.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen storage container optimization design, and in particular to a composite material hydrogen storage bottle structure optimization method. Background Art

[0002] As the application of hydrogen as a clean energy source gradually increases, the structure and material properties of hydrogen storage bottles, as core components for hydrogen storage and transportation, directly affect the safety and service life of hydrogen storage systems. Traditional hydrogen storage bottles are usually made of materials such as steel or aluminum alloys. However, these materials are heavy and may suffer from fatigue damage and crack propagation during long-term use, limiting the safety and life of hydrogen storage bottles.

[0003] In recent years, composite materials have become ideal materials for hydrogen storage bottle manufacturing due to their excellent mechanical properties and lightweight characteristics. In particular, carbon fiber reinforced composite materials (CFRP) have been widely used in the design of high-pressure hydrogen storage bottles due to their high specific strength and specific stiffness. However, the mechanical behavior of composite materials is relatively complex, and they may suffer progressive damage and destruction under load, which poses a potential threat to the reliability of hydrogen storage bottles. Summary of the invention

[0004] The purpose of the present invention is to provide a method for optimizing the structure of a composite material hydrogen storage bottle to solve the problems of low safety and reliability and short service life of the hydrogen storage bottle during long-term use.

[0005] The present invention provides a method for optimizing the structure of a composite material hydrogen storage bottle, comprising:

[0006] Obtain the mechanical performance parameters of the hydrogen storage bottle, the mechanical performance parameters including elastic modulus , shear modulus ;

[0007] The mechanical performance parameters are input into a pre-built progressive damage model, and the mechanical performance parameters are adjusted by an environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions. By simulating the damage evolution of the hydrogen storage bottle under different use conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle are obtained;

[0008] Based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the structural parameters of the hydrogen storage bottle are designed. The structural parameters include wall thickness , number of layers n, fiber angle ;

[0009] The designed structural parameters are optimized by non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method to obtain the optimal structural parameters;

[0010] Numerical simulation, experimental verification and sensitivity analysis are performed on the optimal structural parameters to ensure the safety and robustness of the hydrogen storage bottle designed with the optimal structural parameters in an actual working environment.

[0011] Furthermore, the mechanical performance parameters are adjusted by an environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, including:

[0012] Effect of temperature T and humidity H on elastic modulus and shear modulus The correction functions are , , the mechanical property parameters are corrected by using the correction function to obtain the corrected mechanical property parameters: , , where T is temperature, H is humidity, is the temperature correction coefficient, is the standard ambient temperature, is the humidity correction coefficient, H is the current humidity, The standard ambient humidity.

[0013] Furthermore, by simulating the damage evolution of the hydrogen storage bottle under different use conditions, the change trend of the damage variable D and the service life and residual strength R of the hydrogen storage bottle are obtained, including:

[0014] Simulate the propagation and accumulation of damage in composite materials by tracking the effective strain of the composite material and failure strain The damage state of the composite material is updated by the ratio of , where D is the damage variable, and the damage variable D ranges from 0 to 1. D = 0 means no damage, and D = 1 means that the composite material has completely failed; the effective strain It is obtained by weighting the strain components of the composite material, and the formula is: ,in, is the weight factor of the composite material, is the strain component in each direction;

[0015] The damage evolution formula and the damage increment formula are used to capture the loss process and obtain the change trend of the damage variable D. The formula is:

[0016] , , ,

[0017] in, is the damage value after the n+1th loading, is the damage value after the nth loading, is the damage increment caused by the current loading cycle, C is the constant coefficient of the composite material, and p is the exponent of the damage increment;

[0018] The residual strength R of the hydrogen storage bottle is obtained by calculating the strength of the composite material after damage. The formula is: ,in, is the initial material strength, and D is the current damage state;

[0019] By calculating the number of cycles required for the composite material to reach a critical damage state The service life of the hydrogen storage bottle is obtained by the formula: ,in, is the damage value at failure, is the initial damage value.

[0020] Furthermore, based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the structural parameter design of the hydrogen storage bottle is performed, including:

[0021] The damage variable D is used to determine the wall thickness Design, the formula is: , where C is a constant coefficient, For the wall thickness The effective strain under the condition of p is the damage index, L is the length of the hydrogen storage bottle, is a small increment along the length of the hydrogen storage bottle;

[0022] The number of layers n is designed according to the damage variable D, temperature T and humidity H. The formula is: , ,

[0023] in, represents a constant related to material properties, p is the damage index, Indicates the residual strength of the bottle after the accumulated damage during use;

[0024] According to the damage variable D, temperature T and humidity H, the fiber angle Design, the formula is: , where C2 represents a constant related to material properties, Angle with fiber The relevant effective strain, represents a small change in the fiber angle, and p is the damage index.

[0025] Furthermore, the designed structural parameters are optimized by non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method to obtain the optimal structural parameters, including:

[0026] The structural parameters are iteratively optimized by a non-dominated sorting genetic algorithm NSGA-II to obtain a Pareto solution set, which includes multiple values ​​of the structural parameters, wherein the Pareto solution set satisfies: Solution is a nondominated solution if and only if there is no other solution So that:

[0027] , and there is at least one target ,

[0028] in, It is objective function, m is the number of objectives;

[0029] The Pareto solution set also satisfies the preset optimization goal, which is:

[0030] ,

[0031] ,

[0032] ,

[0033] in: , , ;

[0034] is the mass constraint, which means the mass of the bottle needs to be minimized, and Mass represents the mass;

[0035] It is a strength constraint to ensure that the remaining strength of the bottle meets the minimum requirement. ThresholdStrength represents the strength threshold.

[0036] It is a life constraint to ensure that the service life of the bottle meets the minimum requirement. ThresholdLifetime represents the life threshold.

[0037] The objective function is updated by the simulated annealing algorithm to expand the range of the Pareto solution set. The update formula is: ,

[0038] in, represents the change of the objective function, T represents the current temperature, the initial temperature is high and gradually decreases, and the cooling rate is , is the cooling factor, ranging from 0.8 to 0.99;

[0039] The objective function includes: quality minimization objective function: , intensity maximization objective function: , the objective function of maximizing service life is: , where Mass represents mass, Strength represents strength, and Lifetime represents lifespan;

[0040] The optimal structural parameters are obtained by locally optimizing the Pareto solution set after the expanded range through the gradient descent method. The formula is: ,

[0041] in, is the learning rate, is the gradient of the objective function.

[0042] The present invention has at least the following beneficial effects:

[0043] The mechanical performance parameters of the hydrogen storage bottle are obtained, and the mechanical performance parameters are adjusted through the environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, and the damage development trend of the bottle during its life cycle is predicted. Based on the damage analysis results, the residual strength R and service life of the bottle are further predicted. By introducing the environmental correction coefficient to adjust the performance parameters of the composite material, the performance parameters of the composite material under different working conditions can be accurately obtained, and then the influence of environmental factors such as temperature and humidity on the mechanical properties of the composite material can be accurately reflected, the accuracy and applicability of the progressive damage model and the prediction ability of the model under extreme environmental conditions can be improved, and it can ensure that the mechanical performance parameters of the composite material used in the structural parameter design of the hydrogen storage bottle are more in line with the actual application.

[0044] Based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the structural parameters of the hydrogen storage bottle are designed, including the wall thickness of the hydrogen storage bottle. , number of layers n, fiber angle The parameters are designed, and then the non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method are used to optimize the designed structural parameters to obtain the optimal structural parameters. Specifically, by generating the Pareto optimal solution set, the wall thickness of the hydrogen storage bottle is optimized at the same time. , number of layers n, fiber angle Multiple design goals such as the above are avoided, thereby avoiding the problem of generating local optimal solutions in single-goal optimization, ensuring that the optimization process is not limited by local extreme values, thereby obtaining more accurate and comprehensive structural parameters, and further ensuring the reliability and stability of the designed structural parameters in practical applications. A group of diversified design schemes can be provided, so that designers can choose the most appropriate scheme in different design trade-offs according to specific needs, thereby meeting the optimal design requirements in different application scenarios, and further improving the flexibility and adaptability of the present invention in practical use.

[0045] By combining numerical simulation, experimental verification and sensitivity analysis, the performance of the optimized design of the composite hydrogen storage bottle under different working conditions and environmental conditions can be comprehensively evaluated. Numerical simulation provides a detailed prediction basis for the design, experimental verification ensures the practical feasibility of the design, and sensitivity analysis verifies the robustness of the optimization scheme in actual production and application. This process provides a solid guarantee for the safety, reliability and durability of the hydrogen storage bottle, thereby ensuring the successful implementation of the optimized design in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A flow chart of a composite material hydrogen storage bottle structure optimization method provided by the present invention;

[0047] Figure 2 A flow chart for obtaining and verifying material properties provided by the present invention;

[0048] Figure 3 This is a damage analysis and evaluation flow chart provided by the present invention. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0050] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0051] Example 1: Combination Figure 1-Figure 3 This embodiment is described.

[0052] This embodiment is a method for optimizing the structure of a composite material hydrogen storage bottle, comprising:

[0053] S01: Obtain the mechanical performance parameters of the hydrogen storage bottle, the mechanical performance parameters including elastic modulus , shear modulus ;

[0054] S02: inputting the mechanical performance parameters into a pre-built progressive damage model, adjusting the mechanical performance parameters through an environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, and simulating the damage evolution of the hydrogen storage bottle under different use conditions to obtain the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle;

[0055] S03: Based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the structural parameters of the hydrogen storage bottle are designed. The structural parameters include wall thickness Number of layers n, fiber angle ;

[0056] S04: optimizing the designed structural parameters by using a non-dominated sorting genetic algorithm NSGA-II, a simulated annealing algorithm and a gradient descent method to obtain the optimal structural parameters;

[0057] S05: Performing numerical simulation, experimental verification and sensitivity analysis on the optimal structural parameters to ensure the safety and robustness of the hydrogen storage bottle designed with the optimal structural parameters in an actual working environment.

[0058] The mechanical performance parameters of the hydrogen storage bottle are obtained through tensile testing, compression testing, and shear testing. The mechanical performance parameters are adjusted through the environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, and the damage development trend of the bottle during its life cycle is predicted. Based on the damage analysis results, the residual strength R and service life of the bottle are further predicted. By introducing the environmental correction coefficient to adjust the performance parameters of the composite material, the performance parameters of the composite material under different working conditions can be accurately obtained, and then the influence of environmental factors such as temperature and humidity on the mechanical properties of the composite material can be accurately reflected, the accuracy and applicability of the progressive damage model and the prediction ability of the model under extreme environmental conditions can be improved, and it can ensure that the mechanical performance parameters of the composite material used in the structural parameter design of the hydrogen storage bottle are more in line with the actual application.

[0059] Based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the structural parameters of the hydrogen storage bottle are designed, including the wall thickness of the hydrogen storage bottle. , number of layers n, fiber angle The parameters are designed, and then the non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method are used to optimize the designed structural parameters to obtain the optimal structural parameters. Specifically, by generating the Pareto optimal solution set, the wall thickness of the hydrogen storage bottle is optimized at the same time. , number of layers n, fiber angle Multiple design goals such as the above are avoided, thereby avoiding the problem of generating local optimal solutions in single-goal optimization, ensuring that the optimization process is not limited by local extreme values, thereby obtaining more accurate and comprehensive structural parameters, and further ensuring the reliability and stability of the designed structural parameters in practical applications. A group of diversified design schemes can be provided, so that designers can choose the most appropriate scheme in different design trade-offs according to specific needs, thereby meeting the optimal design requirements in different application scenarios, and further improving the flexibility and adaptability of the present invention in practical use.

[0060] Finally, numerical simulation, experimental verification and sensitivity analysis are carried out on the optimal structural parameters to ensure the safety and robustness of the hydrogen storage bottle designed with the optimal structural parameters in the actual working environment. First, the finite element analysis (FEA) technology is used for numerical simulation to simulate the stress state, damage evolution process and environmental factors of the hydrogen storage bottle under different working conditions. During the simulation process, the geometric model of the hydrogen storage bottle is established according to the structural parameters of the optimized design, and the mechanical properties of the material are defined. Through numerical simulation, the stress, strain and potential damage evolution of the bottle body under different working conditions such as high-pressure inflation and temperature changes can be predicted, thereby providing a theoretical basis for the optimal design.

[0061] The strength, pressure resistance and fatigue resistance of the new hydrogen storage bottle are comprehensively evaluated through static tests, dynamic tests and fatigue tests. The static test simulates the strength of the bottle under working pressure to verify whether the hydrogen storage bottle can withstand the maximum working pressure without yielding or breaking; the dynamic test simulates the impact of temperature changes and load fluctuations on the performance of the bottle, and tests the dynamic response and fatigue resistance of the bottle; the fatigue test evaluates the durability of the hydrogen storage bottle under repeated inflation and deflation cyclic loads, and verifies the fatigue resistance of the hydrogen storage bottle in long-term use. These experiments can verify the accuracy of the numerical simulation results and provide actual data support for the final design.

[0062] In addition to numerical simulation and experimental verification, sensitivity analysis is also required to ensure the robustness of hydrogen storage bottles designed with optimal structural parameters in actual applications. Sensitivity analysis tests the adaptability of the optimization scheme to these factors by evaluating the performance of the design under production processes, environmental changes, and operational errors. For example, geometric errors or material differences that occur during the production process affect the strength and service life of the bottle body; the impact of environmental factors such as high temperature and corrosion on the bottle body also needs to be evaluated. Through sensitivity analysis, it can be verified whether the design is sufficiently adaptable to cope with uncertainties and changes in actual applications.

[0063] By combining numerical simulation, experimental verification and sensitivity analysis, the performance of the optimized design of the composite hydrogen storage bottle under different working conditions and environmental conditions can be comprehensively evaluated. Numerical simulation provides a detailed prediction basis for the design, experimental verification ensures the practical feasibility of the design, and sensitivity analysis verifies the robustness of the optimization scheme in actual production and application. This process provides a solid guarantee for the safety, reliability and durability of the hydrogen storage bottle, thereby ensuring the successful implementation of the optimized design in practical applications.

[0064] Furthermore, the mechanical performance parameters are adjusted by an environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, including:

[0065] Effect of temperature T and humidity H on elastic modulus and shear modulus The correction functions are , , the mechanical property parameters are corrected by using the correction function to obtain the corrected mechanical property parameters: , , where T is temperature, H is humidity, is the temperature correction coefficient, is the standard ambient temperature, is the humidity correction coefficient, H is the current humidity, The standard ambient humidity.

[0066] In order to improve the safety and reliability of hydrogen storage bottles during long-term use and the service life of hydrogen storage bottles, the influence of environmental factors on the mechanical properties of composite materials must be considered. and shear modulus The properties of composite materials will change with changes in environmental factors such as temperature and humidity. and shear modulus The mechanical properties of composite materials will be significantly reduced under high temperature or high humidity. Therefore, a correction function based on environmental conditions is introduced to take into account the influence of the environment on the mechanical properties of composite materials. The corrected mechanical properties parameters are expressed as:

[0067] , ,

[0068] Where T is temperature, H is humidity, and are the correction functions of temperature and humidity on elastic modulus and shear modulus respectively. The correction functions are obtained through experiments based on the actual performance of the material. For example, suppose that for a certain composite material, the elastic modulus is As the temperature T increases, it decreases, and the correction function shows a similar linear relationship: ,

[0069] in, is the temperature correction coefficient, is the standard ambient temperature. Similarly, the effect of humidity H on the mechanical properties of composite materials is also fitted through experimental data, and the corresponding humidity correction function is obtained.

[0070] Under the change of humidity H, the elastic modulus of the composite material and shear modulus Mechanical properties such as thermal conductivity and humidity will be reduced, especially when the composite material has a high hydrophilicity, the absorption of moisture will cause the composite material to swell, soften or debond between layers.

[0071] The humidity correction function can be obtained by fitting the experimental data, and its general form can be expressed as:

[0072] ,

[0073] in, is the humidity correction coefficient, H is the current humidity, is the standard ambient humidity. Humidity correction factor It can be obtained by regression analysis of the mechanical properties test data of composite materials under different humidity conditions.

[0074] If the effect of humidity H on the composite material is an exponential decay characteristic, the humidity correction function is: ,

[0075] in, is the attenuation coefficient affected by humidity, is the standard humidity, and H is the current humidity.

[0076] Assume that for a composite material, the elastic modulus at standard ambient temperature is , under the conditions of temperature T = 80 ° C and humidity H = 70%, the correction coefficient is obtained through experiments and , according to the above correction formula, the corrected elastic modulus of the material is:

[0077] .

[0078] By introducing environmental correction coefficients to adjust the performance parameters of composite materials, the influence of environmental factors such as temperature and humidity on the mechanical properties of composite materials can be accurately reflected, thereby improving the accuracy and applicability of the progressive damage model and the predictive ability of the model under extreme environmental conditions, thereby ensuring that the mechanical performance parameters of composite materials used in the structural parameter design of hydrogen storage bottles are more in line with actual application conditions.

[0079] Furthermore, by simulating the damage evolution of the hydrogen storage bottle under different use conditions, the change trend of the damage variable D and the service life and residual strength R of the hydrogen storage bottle are obtained, including:

[0080] Simulate the propagation and accumulation of damage in composite materials by tracking the effective strain of the composite material and failure strain The damage state of the composite material is updated by the ratio of , where D is the damage variable, and the damage variable D ranges from 0 to 1. D = 0 means no damage, and D = 1 means that the composite material has completely failed; the effective strain It is obtained by weighting the strain components of the composite material, and the formula is: ,in, is the weight factor of the composite material, is the strain component in each direction;

[0081] The damage evolution formula and the damage increment formula are used to capture the loss process and obtain the change trend of the damage variable D. The formula is: , , ,

[0082] in, is the damage value after the n+1th loading, is the damage value after the nth loading, is the damage increment caused by the current loading cycle, C is the constant coefficient of the composite material, and p is the exponent of the damage increment;

[0083] The residual strength R of the hydrogen storage bottle is obtained by calculating the strength of the composite material after damage. The formula is: ,in, is the initial material strength, and D is the current damage state;

[0084] By calculating the number of cycles required for the composite material to reach a critical damage state The service life of the hydrogen storage bottle is obtained by the formula: ,in, is the damage value at failure, is the initial damage value.

[0085] The progressive damage model is used to track the damage evolution of the composite material in each working cycle during the structural parameter design of the hydrogen storage bottle, and to predict the damage accumulation of the bottle body during long-term use with dynamic working conditions such as gas compression and release. Under the action of multiple loading and temperature changes, the service life and residual strength R of the hydrogen storage bottle are predicted.

[0086] By tracking the ratio of effective strain to failure strain, the damage state of the material is updated in real time, and the performance degradation of the structure is predicted. The formula is: , where D is the damage variable, is the effective strain of the anisotropic material, is the failure strain of anisotropic materials. This formula is used to describe the damage accumulation process of composite materials under different loading conditions. It is expressed by the microstructural changes of the composite material and the cracks and fiber breakage inside the composite material, while the failure strain It indicates the failure point of the composite material under extreme conditions.

[0087] Effective Response It is obtained by weighting the strain components of the composite material, and the formula is: ,

[0088] in, is the weight factor of the composite material, is the strain component in each direction. This formula can effectively capture the influence of strains in different directions on the overall damage behavior.

[0089] By tracking the damage evolution of the hydrogen storage bottle under multiple loadings, calculating the damage variable D in each cycle, and updating the damage status of the bottle in real time throughout its life cycle, the damage progression under different working conditions can be predicted.

[0090] For example, in the high-pressure filling and low-temperature environment of a hydrogen storage bottle, as the number of loading times increases, the material will gradually undergo plastic deformation and microcrack expansion, resulting in gradual accumulation of damage. In order to capture this damage process, the following damage evolution formula is used: ,

[0091] in is the damage value after the n+1th loading, is the damage value after the nth loading, is the damage increment caused by the current loading cycle. It is calculated from factors such as material strain, stress or strain energy density.

[0092] Specifically, the damage increment and effective strain The relationship is expressed in the formula express,

[0093] Where C is the constant coefficient of the material, p is the exponent of the damage increment, is the effective strain after each loading. Through this formula, the damage variable D can be updated after each loading, so as to track the evolution of the damage variable D over time, that is, the change trend of the damage variable D.

[0094] Under different environments, the mechanical parameters of composite materials will change. In order to accurately simulate the damage evolution process, it is necessary to introduce an environmental correction factor into the above formula to reflect the strain response of the material under different working conditions. After introducing the environmental correction factor, the damage increment is expressed as: , the corrected damage increment can accurately reflect the changing trend of the damage variable D under different environmental conditions.

[0095] During the damage evolution process, the residual strength R and service life of the bottle can be predicted according to the damage state. The residual strength R is obtained by calculating the strength of the composite material after damage. The formula is: ,in, is the initial material strength, and D is the current damage state. As the damage accumulates, the strength of the material will gradually decay, eventually affecting the overall bearing capacity of the bottle.

[0096] The service life is calculated by predicting the number of cycles required for the material to reach a critical damage state. To estimate, if the bottle is in a certain number of cycles When the failure state is reached, the damage value is Corresponding to the failure criterion of the material, the service life can be calculated by tracking the evolution of the damage: ,in, is the damage value at failure, is the initial damage value.

[0097] If the initial strength of the hydrogen storage bottle is The initial damage is After 10 inflation cycles, the effective strain measured is , then according to the above damage increment formula, assuming C=0.1 and p=2, the damage increment is: , therefore, the total damage after the 10th cycle is: , the residual strength R of the hydrogen storage bottle at this time is: ;

[0098] If the failure criterion is set as: when the damage reaches If the hydrogen storage bottle fails, the service life of the hydrogen storage bottle can be calculated as:

[0099] ,

[0100] Therefore, the expected life of the hydrogen storage bottle under this condition is 500,000 filling cycles.

[0101] Through the above damage analysis and evaluation process, the change trend of the damage variable D, the residual strength R and the service life of the hydrogen storage bottle under different operating conditions can be accurately predicted during the design stage of the hydrogen storage bottle. These data not only provide an important basis for the optimization design of structural parameters, but also can identify potential failure modes in advance to ensure the safety and reliability of hydrogen storage bottles in practical applications. This analysis process is closely integrated with the entire method framework, providing a comprehensive evaluation of material properties and design structures.

[0102] Furthermore, based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the hydrogen storage bottle is designed, including:

[0103] The damage variable D is used to determine the wall thickness Design, the formula is: , , where C is a constant coefficient, For the wall thickness The effective strain under the condition of p is the damage index, L is the length of the hydrogen storage bottle, is a small increment along the length of the hydrogen storage bottle;

[0104] The number of layers n is designed according to the damage variable D, temperature T and humidity H. The formula is: , , ,

[0105] in, represents a constant related to material properties, p is the damage index, Indicates the residual strength of the bottle after the accumulated damage during use;

[0106] According to the damage variable D, temperature T and humidity H, the fiber angle Design, the formula is: , ,

[0107] Where C2 represents a constant related to material properties, Angle with fiber The relevant effective strain, represents a small change in the fiber angle, and p is the damage index.

[0108] h(x) represents the wall thickness at different positions of the hydrogen storage bottle. The wall thickness h(x) of the hydrogen storage bottle directly affects the residual strength R, stiffness and durability of the bottle body, especially under different operating conditions, such as high-pressure inflation, low-temperature environment, etc. The change in the thickness of the hydrogen storage bottle directly affects the damage accumulation process of the bottle body under different environmental conditions. Therefore, in the design process, the wall thickness h(x) is combined with the progressive damage model so that the wall thickness h(x) can be dynamically adjusted.

[0109] The damage variable D will change with the change of wall thickness h(x). The thinner the wall thickness h(x), the higher the stress on the material and the faster the damage accumulates. Therefore, the design goal of the wall thickness h(x) should be to minimize the mass while ensuring that the damage to the bottle is minimized under maximum pressure.

[0110] Combining the progressive damage model and the wall thickness h(x), it can be expressed as: ,

[0111] Where C is a constant coefficient, is the effective strain at the wall thickness h(x), p is the damage index, L is the bottle length, Represents small increments along the length of the hydrogen storage tank.

[0112] The number of layers n of a composite material directly affects the mechanical properties of the material. The material properties of each layer determine the mechanical behavior of the composite material. The more layers there are, the greater the strength and durability of the composite material.

[0113] The damage characteristics of the material and environmental factors will affect the material strength, especially the temperature T and humidity H will affect the elastic modulus of the material and shear modulus , the deformation capacity of the material, which in turn affects its residual strength R, so the number of layers n is designed as: , ,

[0114] in, is the effective strain, is a constant related to material properties, It indicates the residual strength of the bottle after the accumulated damage during use.

[0115] The fiber arrangement direction directly affects the strength and damage resistance of the bottle. The fiber angle is adjusted according to the damage variable D, temperature T and humidity H. Design, the formula is: ,

[0116] in, Angle with fiber The associated effective strain reflects the strain in different fiber directions and the damage evolution of the material. Represents small changes in fiber angle and is used to accumulate the contribution of different fiber angles to the total damage. Fiber Angle The design goal is to select the fiber orientation that maximizes the bottle's strength and durability.

[0117] Assume that the fiber angle of a composite material is Can vary from 30° to 60° depending on fiber angle required by specific design Minimize the damage to accumulate the contribution of the damage variable at each angle and finally obtain the total damage within the angle range. That is, select a specific angle or angle range to minimize D. The formula can be expressed as .

[0118] Furthermore, the designed structural parameters are optimized by non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method to obtain the optimal structural parameters, including:

[0119] The structural parameters are iteratively optimized by a non-dominated sorting genetic algorithm NSGA-II to obtain a Pareto solution set, which includes multiple values ​​of the structural parameters, wherein the Pareto solution set satisfies: Solution is a nondominated solution if and only if there is no other solution So that:

[0120] ,

[0121] and there is at least one target ,

[0122] in, It is objective function, m is the number of objectives;

[0123] The Pareto solution set also satisfies the preset optimization goal, which is:

[0124] ,

[0125] ,

[0126] ,

[0127] in: , , ;

[0128] is the mass constraint, which means the mass of the bottle needs to be minimized, and Mass represents the mass;

[0129] It is a strength constraint to ensure that the remaining strength of the bottle meets the minimum requirement. ThresholdStrength represents the strength threshold.

[0130] It is a life constraint to ensure that the service life of the bottle meets the minimum requirement. ThresholdLifetime represents the life threshold.

[0131] The objective function is updated by the simulated annealing algorithm to expand the range of the Pareto solution set. The update formula is: ,

[0132] in, represents the change of the objective function, T represents the current temperature, the initial temperature is high and gradually decreases, and the cooling rate is , is the cooling factor, ranging from 0.8 to 0.99;

[0133] The objective function includes: quality minimization objective function: , intensity maximization objective function: , the objective function of maximizing service life is: , where Mass represents mass, Strength represents strength, and Lifetime represents lifespan;

[0134] The optimal structural parameters are obtained by locally optimizing the Pareto solution set after the expanded range through the gradient descent method. The formula is: ,

[0135] in, is the learning rate, is the gradient of the objective function.

[0136] The wall thickness of hydrogen storage bottle was calculated by non-dominated sorting genetic algorithm NSGA-II. , number of layers n, fiber angle The three structural parameters are iteratively optimized to generate a Pareto solution set that satisfies the following conditions:

[0137] untie is a nondominated solution if and only if there is no other solution So that:

[0138] ,

[0139] and there is at least one target ,

[0140] in, It is objective function, m is the number of objectives;

[0141] Optimal wall thickness selected by design , number of layers n and fiber angle , thereby maximizing the structural strength and durability of the hydrogen storage bottle, that is, maximizing the residual strength R and maximizing the service life, so the Pareto solution set also meets the preset optimization goal, which is:

[0142] ,

[0143] ,

[0144] ,

[0145] in: , , ;

[0146] is the mass constraint, which means the mass of the bottle needs to be minimized, and Mass represents the mass;

[0147] It is a strength constraint to ensure that the remaining strength of the bottle meets the minimum requirement. ThresholdStrength represents the strength threshold.

[0148] It is a life constraint to ensure that the service life of the bottle meets the minimum requirement. ThresholdLifetime represents the life threshold.

[0149] The Pareto solution set is generated by fast non-dominated sorting, and after multiple generations of evolution, a set of solutions that meet multi-objective optimization is finally obtained.

[0150] In order to improve the global search capability of the optimization algorithm and prevent falling into the local optimal solution, the simulated annealing algorithm is combined to expand the range of the Pareto solution set. The simulated annealing algorithm allows a certain probability of accepting suboptimal solutions during the search process to jump out of the local optimal solution. The objective function update rule in the optimization process is:

[0151] ,

[0152] in, represents the change of the objective function, T is the current temperature, the initial temperature is high and gradually decreases, and the cooling rate is , is the cooling factor, and its value range is 0.8-0.99.

[0153] Then, the expanded Pareto solution set is fine-tuned by the gradient descent method to improve the accuracy of the solution. The formula is: ,in, is the learning rate, is the gradient of the objective function.

[0154] The present invention optimizes the designed structural parameters through genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method, which can effectively overcome the problem of local optimal solution of intelligent optimization algorithm. In the structural parameter optimization of hydrogen storage bottles, this method realizes the combination of global search and local optimization, generates a set of Pareto optimal solutions that balance quality, strength and durability, and ensures the accuracy and stability of structural parameter design.

[0155] It should also be noted that the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of further restrictions, the elements defined by the sentence "comprises one..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements. The words "first", "second" and the like are used to indicate names, but do not indicate any specific order. The above schematically describes the invention and its implementation methods, which is not restrictive. The invention can be implemented in other specific forms without departing from the spirit or basic features of the invention. What is shown in the drawings is only one of the implementation methods of the invention, and the actual structure is not limited thereto. Any figure mark in the claims should not limit the claims involved. Therefore, if a person of ordinary skill in the art is inspired by it, and does not deviate from the purpose of the invention, and designs a structural mode and an embodiment similar to the technical solution without creativity, they should all belong to the scope of protection of this patent.

Claims

1. A method for optimizing the structure of a composite material hydrogen storage bottle, characterized in that: include: Obtain the mechanical performance parameters of the hydrogen storage bottle, the mechanical performance parameters including elastic modulus , shear modulus ; The mechanical performance parameters are input into a pre-built progressive damage model, and the mechanical performance parameters are adjusted by an environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions. By simulating the damage evolution of the hydrogen storage bottle under different use conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle are obtained; Based on the mechanical performance parameters of the hydrogen storage bottle under different working conditions, the change trend of the damage variable D, the service life and the residual strength R of the hydrogen storage bottle, the structural parameters of the hydrogen storage bottle are designed. The structural parameters include wall thickness , number of layers n, fiber angle ,include: Wall thickness Design, the formula is: , where C is a constant coefficient, For the wall thickness The effective strain under the condition of p is the damage index, L is the length of the hydrogen storage bottle, is a small increment along the length of the hydrogen storage bottle; Design the number of layers n, the formula is: , , in, represents a constant related to material properties, p is the damage index, It indicates the residual strength of the bottle after the accumulated damage during use, T indicates the temperature, and H indicates the humidity; Fiber Angle Design, the formula is: , Where C2 represents a constant related to material properties, Angle with fiber The relevant effective strain, represents a small change in the fiber angle, p is the damage index, T represents temperature, and H represents humidity; The designed structural parameters are optimized by non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method to obtain the optimal structural parameters; Numerical simulation, experimental verification and sensitivity analysis are performed on the optimal structural parameters to ensure the safety and robustness of the hydrogen storage bottle designed with the optimal structural parameters in an actual working environment.

2. A composite material hydrogen storage bottle structure optimization method according to claim 1, characterized in that: The mechanical performance parameters are adjusted by the environmental correction function to obtain the mechanical performance parameters of the hydrogen storage bottle under different working conditions, including: Effect of temperature T and humidity H on elastic modulus and shear modulus The correction functions are , , the mechanical property parameters are corrected by using the correction function to obtain the corrected mechanical property parameters: , , where T is temperature, H is humidity, is the temperature correction coefficient, is the standard ambient temperature, is the humidity correction coefficient, H is the current humidity, The standard ambient humidity.

3. A composite material hydrogen storage bottle structure optimization method according to claim 2, characterized in that: By simulating the damage evolution of the hydrogen storage bottle under different use conditions, the change trend of the damage variable D and the service life and residual strength R of the hydrogen storage bottle are obtained, including: Simulate the propagation and accumulation of damage in composite materials by tracking the effective strain of the composite material and failure strain The damage state of the composite material is updated by the ratio of , where D is the damage variable, and the damage variable D ranges from 0 to 1. D = 0 means no damage, and D = 1 means that the composite material has completely failed; the effective strain It is obtained by weighting the strain components of the composite material, and the formula is: ,in, is the weight factor of the composite material, is the strain component in each direction; The damage evolution formula and the damage increment formula are used to capture the loss process and obtain the change trend of the damage variable D. The formula is: ， ， ， in, is the damage value after the n+1th loading, is the damage value after the nth loading, is the damage increment caused by the current loading cycle, C is the constant coefficient of the composite material, and p is the exponent of the damage increment; The residual strength R of the hydrogen storage bottle is obtained by calculating the strength of the composite material after damage. The formula is: ,in, is the initial material strength, and D is the current damage state; By calculating the number of cycles required for the composite material to reach a critical damage state The service life of the hydrogen storage bottle is obtained by the formula: ,in, is the damage value at failure, is the initial damage value.

4. A composite material hydrogen storage bottle structure optimization method according to claim 3, characterized in that: The designed structural parameters are optimized by non-dominated sorting genetic algorithm NSGA-II, simulated annealing algorithm and gradient descent method to obtain the optimal structural parameters, including: The structural parameters are iteratively optimized by a non-dominated sorting genetic algorithm NSGA-II to obtain a Pareto solution set, wherein the Pareto solution set includes multiple values ​​of the structural parameters, wherein the Pareto solution set satisfies: is a nondominated solution if and only if there is no other solution So that: , and there is at least one target , in, It is objective function, m is the number of objectives; The Pareto solution set also satisfies the preset optimization goal, which is: ， ， ， in: , , ; is the mass constraint, which means the mass of the bottle needs to be minimized, and Mass represents the mass; It is a strength constraint to ensure that the remaining strength of the bottle meets the minimum requirement. Threshold Strength represents the strength threshold. It is the life constraint, which is used to ensure that the service life of the bottle meets the minimum requirement. Threshold Lifetime represents the life threshold. The objective function is updated by the simulated annealing algorithm to expand the range of the Pareto solution set. The update formula is: ， in, represents the change of the objective function, T represents the current temperature, the initial temperature is high and gradually decreases, and the cooling rate is , is the cooling factor, ranging from 0.8 to 0.99; The objective function includes: quality minimization objective function: , intensity maximization objective function: , the objective function of maximizing service life is: , where Mass represents mass, Strength represents strength, and Lifetime represents lifespan; The optimal structural parameters are obtained by locally optimizing the Pareto solution set after the expanded range through the gradient descent method. The formula is: , in, is the learning rate, is the gradient of the objective function.

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