Finite element analysis method for vibration characteristics of vertical low-temperature heat-insulation gas cylinder system

Abstract

The invention provides a vibration characteristic finite element analysis method for a vertical low-temperature heat-insulation gas cylinder system. The vibration characteristic finite element analysis method comprises the following steps: constructing a three-dimensional model of the vertical low-temperature heat-insulation gas cylinder system with different liner wall thicknesses by using Solidworks; the method comprises the following steps: respectively importing three-dimensional models of vertical low-temperature heat-insulation gas cylinder systems with different liner wall thicknesses into ANSYS finite element analysis software, setting material attributes according to reality, and performing contact and grid division; the method comprises the following steps: setting loads and constraints according to actual vibration test working conditions, and calculating first six-order inherent frequencies of vertical low-temperature heat-insulation gas cylinder systems with different liner wall thicknesses in an ANSYS modal analysis module; the resonant frequency of the vertical low-temperature heat-insulation gas cylinder system with different wall thicknesses of the inner container in a standard frequency range is calculated by using the harmonic response analysis module, and a theoretical basis is provided for research on vibration characteristics of the vertical low-temperature heat-insulation gas cylinder system.

Description

Technical Field

[0001] The invention relates to the field of industrial gas cylinder vibration characteristic analysis, and in particular to a vibration characteristic finite element analysis method for a vertical cryogenic insulated gas cylinder system. Background Art

[0002] Cryogenic insulated gas cylinders have the ability to store and transport cryogenic liquids such as liquid oxygen, liquid nitrogen, and liquid argon under pressure. Compared with ordinary gas cylinders, their structural design is more complex and their production costs are also higher. During vehicle transportation, cryogenic insulated gas cylinders are subjected to continuous vibration, which may cause vibration failure, and then lead to failure of the structural strength or stiffness of the gas cylinder. In extreme cases, it may also lead to safety accidents. In order to effectively prevent the risk of vibration failure, vibration testing must be performed to comprehensively evaluate the overall vibration resistance of the gas cylinder during the product development and design stage. However, it is worth noting that once the vibration test shows failure, it will mean that additional time and money will be required to redesign and retest the gas cylinder.

[0003] At present, the development of vehicle-mounted cryogenic insulated gas cylinders is still in its early stages, and there are few studies on their vibration characteristics. Hao Chaoyang et al. (Hao Chaoyang, Ding Hua, Li Muze, et al. Structural strength and vibration fatigue analysis of vehicle-mounted cryogenic insulated gas cylinders [J]. Cryogenics and Superconductivity, 2024, 52(06): 58-64+102.) studied the strength and fatigue of vehicle-mounted cryogenic insulated gas cylinders filled with liquid hydrogen under braking conditions based on ANSYS; Liu Rui et al. (Liu Rui, Chen Zuzhi, Huang Qianghua, et al. Numerical simulation analysis of the influence of filling volume and cylinder length on the resonance frequency of vehicle-mounted LNG gas cylinders [J]. Journal of Chemical Industry, 2019, 70(11): 4486-4496.) calculated the natural frequency of vehicle-mounted LNG gas cylinders under different filling rates and different cylinder lengths based on ANSYS simulation. Mir et al. (MIR O, SHAKOURIM, Ashory M R. Gas pressure and density effects on vibration of cylindrical pressure vessels: analytical, numerical and experimental analysis[J]. SN Applied Sciences, 2020, 2(1)) studied the natural frequency and vibration mode of gas cylinders under different gases and different internal pressures through modal tests and finite element software respectively.

[0004] Current research mainly focuses on horizontal gas cylinders with strap constraints, while research on the vibration characteristics of vertical cryogenic insulated gas cylinders, especially under special vertical external frame constraints, is relatively insufficient. However, vertical cryogenic insulated gas cylinders are widely used in transportation. For example, live fish transport vehicles need to be equipped with vertical liquid oxygen cylinders to supply oxygen to fish. In order to ensure the transportation safety of vertical cryogenic insulated gas cylinder systems in such vehicles, the present invention proposes a finite element analysis method for the vibration characteristics of vertical cryogenic insulated gas cylinder systems, which can provide a theoretical basis for the study of the vibration characteristics of vertical cryogenic insulated gas cylinder systems. Summary of the invention

[0005] The purpose of the present invention is to construct a vertical cryogenic insulated gas cylinder system structure taking into account an external frame, analyze the vibration characteristics of the vertical cryogenic insulated gas cylinder system by a finite element analysis method, and propose a finite element analysis method for the vibration characteristics of a vertical cryogenic insulated gas cylinder system to solve the resonance problem that may occur during transportation.

[0006] The present invention is achieved by at least one of the following technical solutions.

[0007] A finite element analysis method for vibration characteristics of a vertical cryogenic insulated gas cylinder system comprises the following steps:

[0008] S1. Construct a three-dimensional model of a vertical cryogenic insulated gas cylinder system with different liner wall thicknesses using three-dimensional modeling software;

[0009] S2. Construct a finite element model of a vertical cryogenic insulated gas cylinder system, import the three-dimensional model of the vertical cryogenic insulated gas cylinder system into a finite element analysis software, set material properties and contacts according to actual conditions, and perform meshing to obtain a finite element model of the vertical cryogenic insulated gas cylinder system;

[0010] S3. Modal analysis under the influence of different liner wall thicknesses. Set loads and constraints according to actual vibration test conditions, and calculate the first six natural frequencies of the vertical cryogenic insulated gas cylinder system with different liner wall thicknesses in the modal analysis module of the finite element analysis software;

[0011] S4. Harmonic response analysis within the standard frequency range. The modal superposition method is used to perform harmonic response analysis on vertical cryogenic insulated gas cylinder systems with different liner wall thicknesses to analyze the resonant frequency within the standard frequency range.

[0012] S5. Compare the resonance frequencies of the vertical cryogenic insulated gas cylinder systems with different liner wall thicknesses obtained in step S4 to obtain the influence of the liner wall thickness on the vibration characteristics of the vertical cryogenic insulated gas cylinder system.

[0013] Furthermore, the vertical cryogenic insulated gas cylinder system of step S1 includes a cryogenic insulated gas cylinder and a gas cylinder frame.

[0014] Furthermore, the three-dimensional model of the cryogenic insulated gas cylinder includes the upper and lower heads of the outer shell, the outer shell cylinder, the upper and lower heads of the liner, the liner cylinder, the upper and lower supports, the seismic isolation plate, the positioning cylinder and the positioning sleeve.

[0015] Furthermore, the three-dimensional model of the gas cylinder frame includes a top component and a bottom component, the top component includes an axial support, and the bottom component includes a radial support and a mounting hole.

[0016] Furthermore, the material properties of step S2 include density, elastic modulus, and Poisson's ratio.

[0017] Furthermore, the virtual mass method is used to make 50% of the liquid nitrogen filled in the gas cylinder equivalent to the lower head of the inner liner and the lower half of the cylinder.

[0018] Furthermore, the calculation formula of the virtual mass method is as follows:

[0019]

[0020] Among them, ρ e represents the equivalent density, ρ l Indicates the density of the filling medium, ρ in Indicates the density of the gas cylinder liner, V indicates the effective volume of the gas cylinder, m in Indicates the quality of the gas cylinder liner. Indicates the filling rate.

[0021] Furthermore, the meshing in step S2 utilizes the ANSYS Mesh module of the ANSYS finite element analysis software, and adopts the Hex Dominant method to mesh the inner liner and the outer shell of the gas cylinder, and the remaining parts are automatically meshed, and the mesh unit type is Solid186 entity unit.

[0022] Furthermore, the loads and constraints in step S3 are set through the Static Structural module, the nominal working pressure is evenly distributed on the inner liner of the gas cylinder, the gravity acceleration is added in the negative direction of the Y axis, and fixed supports are set at the mounting holes at the bottom of the gas cylinder frame according to the actual vibration test conditions.

[0023] Furthermore, the natural frequency in step S3 is performed through the Modal module of ANSYS, wherein the frequency extraction order is set to the first six orders, and the Block Lanczos method is used to solve the mode.

[0024] Furthermore, the resonant frequency in step S4 is calculated through the Harmonic Response module of ANSYS, and the modal superposition method is adopted. The excitation acceleration is set to 0.5g, and the acceleration directions are perpendicular to the axis of the cryogenic insulated gas cylinder and along the axis of the cryogenic insulated gas cylinder, respectively. The sweep frequency range is set according to the standard GB / T 24159-2022, and the damping coefficient is set. After calculation, the amplitude-frequency response curve is obtained to analyze the resonant frequency.

[0025] The finite element analysis method for vibration characteristics of a vertical cryogenic insulated gas cylinder system proposed in the present invention has the following beneficial effects compared with the existing technology:

[0026] The present invention proposes a vertical gas cylinder outer frame, and considers vertical cryogenic insulated gas cylinders with different inner wall thicknesses and the outer frame as an integral system. This approach not only breaks through the limitations of previous studies that only focus on a single gas cylinder without considering external constraint components or simplified models, but also is closer to actual working conditions, making the analysis results more accurate and comprehensive, and being able to conduct a comprehensive analysis of the system consisting of cryogenic insulated gas cylinders and outer frames.

[0027] The present invention uses a finite element analysis method, which can efficiently and accurately solve the natural frequency and resonant frequency of the vertical cryogenic insulated gas cylinder system. The natural frequency and resonant frequency are important parameters for evaluating the vibration characteristics of the structure. They are directly related to the stability and safety of the system under external excitations. Especially in dynamic environments such as vehicle transportation, the vertical cryogenic insulated gas cylinder system may be affected by various complex excitations. Through precise calculations, potential vibration risk points can be accurately identified, providing strong support for structural optimization.

[0028] The invention has a wide range of applications and is not only suitable for the structural optimization design of a vertical cryogenic insulated gas cylinder system, but can also provide a reference for the revision of relevant standards.

[0029] In summary, the finite element analysis method for the vibration characteristics of a vertical cryogenic insulated gas cylinder system proposed in the present invention can improve the accuracy and comprehensiveness of the analysis, and can provide a reference for the structural optimization design of the vertical cryogenic insulated gas cylinder system and the revision of relevant standards to prevent structural resonance damage and ensure the safe transportation of gas cylinders. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1It is a flow chart of the finite element analysis method of vibration characteristics of a vertical cryogenic insulated gas cylinder system of an embodiment;

[0032] Figure 2 It is a schematic diagram of a three-dimensional model of a vertical cryogenic insulated gas cylinder system of an embodiment;

[0033] Figure 3 It is a schematic diagram of mesh division of a finite element model of a vertical cryogenic insulated gas cylinder system of an embodiment;

[0034] Figure 4 It is a schematic diagram of the natural frequency of a vertical cryogenic insulated gas cylinder system of an embodiment;

[0035] Figure 5 It is a schematic diagram of the amplitude-frequency response curve of the vertical cryogenic insulated gas cylinder system of the embodiment. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention, but the described embodiments are only part of the embodiments of the present invention, and the implementation of the present invention is not limited thereto. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, this embodiment provides a finite element analysis method for vibration characteristics of a vertical cryogenic insulated gas cylinder system, comprising the following steps:

[0038] S1, such as Figure 2 As shown, the three-dimensional model of the vertical cryogenic insulated gas cylinder system is constructed using Solidworks software, including the cryogenic insulated gas cylinder and the gas cylinder frame, wherein the three-dimensional model of the cryogenic insulated gas cylinder includes the upper and lower heads of the outer shell, the outer shell cylinder, the upper and lower heads of the liner, the liner cylinder, the upper and lower supports, the seismic isolation plate, the positioning cylinder and the positioning sleeve, and the three-dimensional model of the gas cylinder frame includes the top component and the bottom component, the top component includes an axial support, and the bottom component includes radial supports and mounting holes. The three-dimensional model of the vertical cryogenic insulated gas cylinder system ignores non-pressure-bearing components such as valve pipeline systems, and ignores welds and chamfers;

[0039] As an embodiment, the main dimensions of the cryogenic insulated gas cylinder of this embodiment include: the nominal diameter of the inner liner is 450mm, the inner tube length is 1188mm, the nominal diameter of the outer shell is 504mm, and the outer tube length is 1348mm; the specifications of the gas cylinder frame are 600mm×600mm×1500mm.

[0040] S2. Construct a finite element model of a vertical cryogenic insulated gas cylinder system, import the three-dimensional model of the vertical cryogenic insulated gas cylinder system into ANSYS finite element analysis software, set material properties and contacts according to actual conditions, and perform meshing to obtain a finite element model of the vertical cryogenic insulated gas cylinder system;

[0041] As an embodiment, the material properties include density, elastic modulus, and Poisson's ratio. As shown in Table 1, the inner and outer shells of the cryogenic insulated gas cylinder are made of austenitic stainless steel 06Cr19Ni10 (S30408), the gas cylinder frame body is made of carbon structural steel (Q235-B), and the seismic isolation plate is made of rubber material.

[0042] Table 1 Material properties of vertical cryogenic insulated gas cylinder system

[0043] structure Material <![CDATA[Density / kg·m -3 > Elastic modulus / GPa Poisson's ratio Cryogenic insulated gas cylinder (excluding the seismic isolation plate) S30408 7930 193 0.29 Isolation board rubber 1500 0.08 0.48 Gas cylinder frame Q235-B 7850 210 0.274

[0044] The virtual mass method is used to make 50% of the liquid nitrogen filled in the gas cylinder equivalent to the lower head of the inner liner and the lower half of the cylinder. This method ignores the influence of liquid sloshing and degenerates the solid-liquid coupling problem into a simple solid dynamics problem, which greatly simplifies the solution process of the solid-liquid coupling problem. In this embodiment, the density of liquid nitrogen is 810 kg·m -3 , the calculation formula of virtual mass method is as follows:

[0045]

[0046] Among them, ρ e represents the equivalent density, ρ l Indicates the density of the filling medium, ρ in Indicates the density of the gas cylinder liner, V indicates the effective volume of the gas cylinder, m in Indicates the quality of the gas cylinder liner. Indicates the filling rate (the value is 50%).

[0047] The contact settings are as follows: "No Separation" contact is used between the positioning cylinder and the positioning sleeve of the lower support, "Frictional" contact is used between the isolation plate and the lower head of the shell, and "Bonded" contact is used for the connection of other components.

[0048] The mesh division uses ANSYS Mesh module and Hex Dominant method to mesh the inner liner and outer shell of the gas cylinder, and the rest of the parts are automatically meshed. The mesh unit type is Solid186 entity unit. Figure 3 The figure shows the schematic diagram of mesh division.

[0049] S3. Modal analysis under the influence of different liner wall thicknesses. Set loads and constraints according to actual vibration test conditions, and calculate the first six natural frequencies of the vertical cryogenic insulated gas cylinder system with different liner wall thicknesses in the ANSYS modal analysis module;

[0050] The loads and constraints are set through the Static Structural module. The nominal working pressure is evenly distributed on the inner liner of the gas cylinder, that is, "Pressure" is added to the surface of the inner liner of the gas cylinder, and the value is 2.3MPa. The gravity acceleration is added in the negative direction of the Y axis, that is, the acceleration in the Y axis direction is set to -9.81m / s 2 Then, the Static Structural module results are loaded into the Modal module in a prestressed form for modal analysis. According to the actual vibration test conditions, fixed supports are set at the mounting holes at the bottom of the gas cylinder frame, that is, "Fixed Support" constraints are added to the two mounting holes at the bottom, front, back, left, and right.

[0051] The natural frequency is calculated by the Modal module of ANSYS. As an embodiment, the input value of "Max Modes to Find" in "Analysis Settings" is 6, that is, the frequency extraction order is the first six orders, and the "Direct" method is selected in "Solver Type", which is equivalent to the classic Block Lanczos method for solving the mode. Right-click "Solution" and then click "Solve" to calculate. The calculation results, that is, the first six natural frequencies, are displayed in the "Tabular Data" window, which are organized as follows: Figure 4 As shown. Figure 4 It can be found that the first six natural frequencies of the vertical cryogenic insulated gas cylinder system under this wall thickness are 26.52Hz, 26.75Hz, 35.11Hz, 42.87Hz, 48.50Hz, and 58.37Hz, respectively. The first three natural frequencies are in the range of 8-40Hz. According to the standard, it is necessary to be vigilant about the resonant frequencies in this frequency range. During the vehicle-mounted process, if resonance occurs, large-amplitude vibration will occur. Therefore, further harmonic response analysis is required to determine the resonant frequency.

[0052] S4. Harmonic response analysis within the standard frequency range. The modal superposition method is used to perform harmonic response analysis on vertical cryogenic insulated gas cylinder systems with different liner wall thicknesses to analyze the resonant frequency within the standard frequency range.

[0053] The resonant frequency is analyzed through the Harmonic Response module (harmonic response analysis module) of ANSYS, and the modal superposition method is adopted. The connection can be established by directly dragging the Harmonic Response module to the Solution of the Modal module to perform the modal superposition method.

[0054] The excitation acceleration is introduced into Acceleration through Harmonic Response. When the vibration is perpendicular to the axis of the cryogenic insulation cylinder, 4900 mm / s is input in the X-axis direction. 2 , i.e. 0.5g; when vibrating along the axis of the cryogenic insulated gas bottle, the input speed in the Y-axis direction is 4900mm / s 2 , i.e. 0.5g;

[0055] The frequency sweep range is 8-40 Hz according to the standard GB / T 24159-2022. In the Analysis Settings under Harmonic Response, the minimum value of the range is set to 8 Hz, and the maximum value of the range is set to 40 Hz.

[0056] The damping setting is set to 0.04 in Damping Ratio through Analysis Settings under Harmonic Response;

[0057] Click Solve to perform the calculation. By adding Frequency Responce in Solution, select a point on the shell head for amplitude-frequency analysis, and display the amplitude-frequency response curve in the range of 8-40Hz, as shown in the figure. Figure 5 As shown in the figure, the amplitude-frequency response curve is analyzed to obtain the resonant frequency of the vertical cryogenic insulated gas bottle system in the range of 8-40Hz. It is found that when the frequency is 26.8Hz, the amplitude increases to the maximum, reaching 77185mm / s 2 , indicating that when the vertical cryogenic insulated gas cylinder system vibrates at an acceleration of 0.5g in a direction perpendicular to the axis of the cryogenic insulated gas cylinder, resonance occurs, that is, the resonance frequency is 26.8Hz, which is within the range of 8-40Hz. Therefore, further structural optimization is required to prevent resonance from occurring during vehicle operation, thereby damaging the gas cylinder system structure and causing safety accidents.

[0058] S5, comparing the resonant frequencies of the vertical cryogenic insulated gas cylinder systems with different liner wall thicknesses obtained in step S4;

[0059] According to the design requirements, change the wall thickness of the gas cylinder liner in the Solidworks software, repeat steps S1 to S4, obtain the resonant frequency of the vertical cryogenic insulated gas cylinder system with different liner wall thicknesses, and compare and analyze to obtain the influence of the liner wall thickness on the vibration characteristics of the vertical cryogenic insulated gas cylinder system. The present invention has certain versatility in the calculation of the resonant frequency of the vertical cryogenic insulated gas cylinder system, and can obtain more natural frequencies and resonant frequencies under working conditions by changing the filling medium, filling amount, gas cylinder aspect ratio, liner wall thickness, external frame constraint mode, etc., providing a certain reference basis for the design of vertical cryogenic insulated gas cylinders, the prevention of structural resonance damage during use, and the evaluation of vibration characteristics and the formulation of standards.

[0060] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A finite element analysis method for vibration characteristics of a vertical cryogenic insulated gas cylinder system, characterized in that: The following steps are involved: S1. Construct a three-dimensional model of a vertical cryogenic insulated gas cylinder system with different liner wall thicknesses using three-dimensional modeling software; S2. Construct a finite element model of a vertical cryogenic insulated gas cylinder system, import the three-dimensional model of the vertical cryogenic insulated gas cylinder system into a finite element analysis software, set material properties and contacts according to actual conditions, and perform meshing to obtain a finite element model of the vertical cryogenic insulated gas cylinder system; S3. Modal analysis under the influence of different liner wall thicknesses. Set loads and constraints according to actual vibration test conditions, and calculate the first six natural frequencies of the vertical cryogenic insulated gas cylinder system with different liner wall thicknesses in the modal analysis module of the finite element analysis software; S4. Harmonic response analysis within the standard frequency range. The modal superposition method is used to perform harmonic response analysis on vertical cryogenic insulated gas cylinder systems with different liner wall thicknesses to analyze the resonant frequency within the standard frequency range. S5. Compare the resonance frequencies of the vertical cryogenic insulated gas cylinder systems with different liner wall thicknesses obtained in step S4 to obtain the influence of the liner wall thickness on the vibration characteristics of the vertical cryogenic insulated gas cylinder system.

2. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 1 is characterized in that: The vertical cryogenic insulated gas cylinder system of step S1 includes a cryogenic insulated gas cylinder and a gas cylinder frame.

3. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 2 is characterized in that: The three-dimensional model of the cryogenic insulated gas cylinder includes the upper and lower heads of the outer shell, the outer shell cylinder, the upper and lower heads of the liner, the liner cylinder, the upper and lower supports, the seismic isolation plate, the positioning cylinder and the positioning sleeve.

4. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 3 is characterized in that: The three-dimensional model of the gas cylinder frame includes a top component and a bottom component. The top component includes an axial support, and the bottom component includes a radial support and mounting holes.

5. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 1 is characterized in that: The material properties in step S2 include density, elastic modulus, and Poisson's ratio.

6. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 4 is characterized in that: The virtual mass method is used to make 50% of the liquid nitrogen filled in the gas cylinder equivalent to the lower head of the inner liner and the lower half of the cylinder.

7. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 6 is characterized in that: The calculation formula of the virtual mass method is as follows: Among them, ρ e represents the equivalent density, ρ l Indicates the density of the filling medium, ρ in Indicates the density of the gas cylinder liner, V indicates the effective volume of the gas cylinder, m in Indicates the quality of the gas cylinder liner. Indicates the filling rate.

8. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 1 is characterized in that: The meshing in step S2 is performed using the ANSYS Mesh module of the ANSYS finite element analysis software, and the HexDominant method is used to mesh the inner liner and the outer shell of the gas cylinder, and the remaining parts are automatically meshed, and the mesh unit type is Solid186 entity unit.

9. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 1 is characterized in that: The loads and constraints in step S3 are set through the Static Structural module. The nominal working pressure is evenly distributed on the inner liner of the gas cylinder, and the gravity acceleration is added in the negative direction of the Y axis. Fixed supports are set at the mounting holes at the bottom of the gas cylinder frame according to the actual vibration test conditions.

10. The vibration characteristics finite element analysis method of a vertical cryogenic insulated gas cylinder system according to claim 1, characterized in that: The natural frequency in step S3 is performed through the Modal module of ANSYS, in which the frequency extraction order is set to the first six orders, and the Block Lanczos method is used to solve the mode.

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