A method for predicting leakage rate of rubber seal in complex space environment effect

Abstract

This invention proposes a method for predicting the leakage rate of rubber seals under complex spatial environmental effects. This method, for the first time, suggests that the total leakage rate of rubber seals consists of two leakage modes: leakage from the rubber sealing material itself and leakage at the microscopic interface. It analyzes the changes in the proportion of these two leakage modes and the leakage rate over time under single-factor and multi-factor spatial environmental effects, establishes the correlation between the leakage rate of rubber seals and time, and constructs a mathematical model for predicting the leakage rate of the rubber sealing material itself and the interface leakage rate under multi-factor spatial environmental effects. This invention can predict the leakage rate of the rubber sealing material itself and the interface leakage rate under multi-factor spatial environmental effects, and improves the calculation accuracy of the leakage rate of rubber seals under the influence of spatial environmental effects.

Description

Technical Field

[0001] This invention relates to a method for predicting the leakage rate of rubber seals under complex space environment effects, belonging to the research field of the evolution mechanism of sealing performance of rubber materials. Background Technology

[0002] Spacecraft extensively utilize rubber seals for sealing, from large components like space station hatches and propulsion subsystem valves to smaller aerospace component packages. These rubber seals provide a safe and stable working environment for astronauts, propulsion materials, and circuitry in these applications. Any leakage in the sealing structure will directly affect the normal operation of the spacecraft. Therefore, for spacecraft systems with long-term on-orbit service requirements, the rubber sealing devices are a weak point affecting their performance.

[0003] Current analyses of leakage rates in long-life rubber seals largely focus on leakage rates considering the effects of thermo-oxidative aging, lacking methods for predicting leakage rates under the combined effects of complex spatial environments (such as high-low temperature alternation, vacuum, atomic oxygen, and ultraviolet irradiation). However, high-low temperature alternation damages rubber materials, vacuum causes the precipitation of rubber components, and atomic oxygen and ultraviolet irradiation alter the composition and surface morphology of rubber materials. These factors inevitably lead to the degradation of rubber seal performance. Furthermore, current analyses of rubber seal leakage primarily focus on leakage at the sealing interface, lacking analysis of leakage within the rubber seal material itself.

[0004] Therefore, it is urgent to develop a method for predicting the leakage rate of rubber seals under the effects of complex space environment, to analyze the leakage of the rubber sealing material itself and the interface leakage under the effects of complex space environment, and to predict the performance of rubber seals of spacecraft in orbit at different service periods. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a method for predicting the leakage rate of rubber seals under the effects of complex space environment. This method is used to analyze the total leakage rate of rubber seals in spacecraft that are under the effects of complex space environment for a long time, and can predict the leakage rate of rubber seals in different service periods with relatively accurate results.

[0006] The technical solution of this invention:

[0007] A method for predicting the leakage rate of rubber seals under complex space environment effects, characterized by the following steps:

[0008] (1) The stress-strain constitutive relationship, thermal expansion coefficient and permeability coefficient of rubber sealing material under single-factor and multi-factor complex space environment effects were tested respectively, as well as the surface micromorphology of metal material in contact with rubber sealing material under single-factor and multi-factor complex space environment effects.

[0009] (2) Construct a leakage model of the rubber sealing material body, and include the permeability coefficient of the rubber sealing material under single-factor and multi-factor complex spatial environment effects into the model respectively, and calculate the leakage rate of the rubber sealing material body under single-factor and multi-factor complex spatial environment effects respectively.

[0010] (3) Establish a theoretical model for macroscopic contact performance analysis of rubber seals. Based on the stress-strain constitutive relationship of rubber seal materials under single-factor and multi-factor complex spatial environment effects, calculate the contact pressure and contact width of rubber seals under single-factor and multi-factor complex spatial environment effects respectively.

[0011] (4) Construct a micro-contact performance analysis model for rubber seals, and combine the micro-morphology of metal material surface, rubber seal contact pressure and contact width under single-factor and multi-factor complex spatial environment effects to calculate the leakage rate of rubber seal interface under single-factor and multi-factor complex spatial environment effects respectively.

[0012] (5) Determine the variation law of leakage rate of rubber sealing material body leakage and interface leakage under single factor spatial environment effect, obtain the influence weight of leakage rate of rubber sealing material under single factor spatial environment effect, and the variation law of proportion of the two leakage modes.

[0013] (6) Determine the variation law of leakage rate of two leakage modes, namely body leakage and interface leakage, under the multi-factor space environment effect, and obtain the variation law of the proportion of the two leakage modes under the multi-factor space environment effect.

[0014] (7) Establish mathematical models for predicting the leakage rate of the rubber sealing material body and the interface leakage rate under the multi-factor spatial environment effect, and predict the leakage rate of the rubber sealing material body and the interface leakage rate, as well as the total leakage rate under the multi-factor spatial environment effect; the total leakage rate is the sum of the leakage rates of the two leakage modes of the rubber seal.

[0015] Furthermore, the single-factor space environment effect refers to any one of the following: atmospheric pressure-thermal cycling space environment effect, vacuum-thermal cycling space environment effect, atomic oxygen space environment effect with different irradiation doses, and ultraviolet irradiation space environment effect with different irradiation doses; the multi-factor space environment effect refers to any one of the following: the combined space environment effect of atmospheric pressure-thermal cycling and vacuum-thermal cycling; the combined space environment effect of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen irradiation; and the combined space environment effect of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen irradiation, and ultraviolet irradiation.

[0016] Furthermore, during the test, the rubber sealing material was a prepared O-ring rubber seal.

[0017] Furthermore, the method for calculating the leakage rate of the rubber sealing material body is as follows:

[0018] Based on Darcy's porous media theory, a leakage rate analysis model for rubber sealing materials based on porous media structures is constructed. In modeling, the shape of the rubber sealing material is taken as its shape under compression at a given compression rate. The compressed rubber sealing material is divided into n sub-regions along the horizontal direction, and the shape of the rubber sealing material corresponding to each sub-region is considered as a rectangle. The leakage rate Q of the rubber sealing material is... k The calculation formula is:

[0019]

[0020] In the formula, r is the inner diameter of the rubber sealing material; D r v is the cross-sectional diameter of the rubber sealing material; i is the i-th region divided by the leakage rate analysis model of the rubber sealing material; i Let be the fluid velocity at the outlet of the i-th region in the analysis model of the leakage rate of the rubber sealing material body;

[0021] Where v i The calculation formula is:

[0022]

[0023] In the formula, ΔP is the pressure difference between the upstream and downstream sides of the rubber sealing material structure, L is the length of the rubber sealing material structure in the flow direction, μ is the fluid viscosity, and k is the viscosity of the fluid. i Let be the permeability of the i-th region of the rubber seal.

[0024] Furthermore, the macroscopic contact performance analysis theoretical model of rubber seals refers to the finite element model constructed using computer finite element software; the calculation method for the contact pressure and contact width of the rubber sealing material is as follows: in the macroscopic contact performance analysis theoretical model of rubber seals, pressure is applied to the rubber sealing material from top to bottom to deform it, and the stress-strain constitutive relationship and thermal expansion coefficient of the rubber sealing material under single-factor and multi-factor spatial environmental effects are applied to the finite element model, and the contact pressure and contact width of the rubber sealing material under single-factor and multi-factor spatial environmental effects are obtained through finite element calculation.

[0025] Furthermore, the calculation process for the leakage rate at the rubber sealing interface is as follows:

[0026] A computational domain is selected along the circumferential direction at the contact surface of the rubber sealing material. This computational domain is then divided into several sub-regions. The flow conductance calculation method for each sub-region is as follows:

[0027] Based on the microscopic morphology of the metal material surface in contact with the rubber sealing material under single-factor and multi-factor spatial environmental effects, the cross-sectional dimensions of the microscopic leakage channel of the rubber sealing material under single-factor and multi-factor spatial environmental effects are calculated by the rubber sealing microscopic contact performance analysis model.

[0028] The equivalent hydraulic diameter d of the equivalent circular cross-section pipe of the micro-leakage channel of the rubber sealing material is calculated by the formula: d = 4A / l, where A is the cross-sectional area of ​​the micro-leakage channel of the rubber sealing material and l is the perimeter of the cross-section of the micro-leakage channel of the rubber sealing material.

[0029] The flow regime in the leakage channel is determined based on the equivalent hydraulic diameter, and the determination criteria are as follows: It is a viscous flow; It is a molecular flow; It is a viscous-molecular flow; where, The mean free path of gas molecules;

[0030] In viscous flow, the flow conductance U of the equivalent circular cross-section pipe n The calculation formula is as follows:

[0031]

[0032] Where L′ is the pipe length and η is the gas viscosity coefficient. The average pressure in the pipeline. p1 and p2 are the gas pressures at both ends of the equivalent circular cross-section pipe, respectively;

[0033] During molecular flow, the conductance U of the equivalent circular cross-section pipe f The calculation formula is as follows:

[0034]

[0035] Where R is the molar gas constant, 8.3143; M is the molar mass of the gas; T is the temperature; and d is the pipe diameter.

[0036] In viscous-molecular flow, the conductance U of the equivalent circular cross-section pipe n.f The calculation formula is as follows:

[0037]

[0038] Where η is the gas viscosity coefficient. The average pressure in the pipeline. p1 and p2 are the gas pressures at both ends of the pipe, respectively;

[0039] The total conductance of a single radial leakage is obtained by connecting the conductances of each sub-region in series, and then the leakage rate caused by a single radial leakage channel is calculated. The leakage rate caused by a single radial leakage channel is multiplied by the number of radial micro-leakage channels of the rubber sealing material to obtain the leakage rate of the sealing ring interface.

[0040] Furthermore, the variation patterns of leakage rates under two modes—bulk leakage and interfacial leakage—of rubber sealing materials under single-factor spatial environmental effects were determined, including:

[0041] The leakage rate of rubber sealing materials under atmospheric pressure-thermal cycling environment was tested to obtain the variation law of the leakage of the rubber sealing material body and the interface leakage with the number of atmospheric pressure-thermal cycles and time, as well as the change of the ratio weight of the two leakage modes.

[0042] The leakage rate of rubber sealing materials under the vacuum-thermal cycling environment effect was tested to obtain the changes in the leakage of the rubber sealing material body and the interface leakage with the number of vacuum-thermal cycles and time, as well as the changes in the proportion and weight of the two leakage modes.

[0043] Under the same number of thermal cycles and the same high and low temperature environments, the differences in the effects of atmospheric pressure-thermal cycling and vacuum-thermal cycling on the leakage rate of rubber seals were compared to obtain the weights of the effects of the two operating conditions on the leakage rate of rubber seals.

[0044] The leakage rate of rubber seals under different irradiation doses was tested using helium mass spectrometry vacuum leak detection method. The variation law of rubber seal leakage rate with irradiation dose and time under the influence of atomic oxygen effect was obtained. The variation law of rubber seal material leakage and interface leakage with service time under the influence of atomic oxygen effect of different irradiation doses was analyzed, as well as the change of the ratio weight of the two leakage modes.

[0045] Determine the weights of the effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen on the bulk leakage rate and interfacial leakage rate of rubber sealing materials;

[0046] The leakage rate of rubber seals under different irradiation doses was tested using helium mass spectrometry vacuum leak detection method to obtain the variation law of rubber seal leakage rate with irradiation dose and time.

[0047] To determine the changes in leakage and interface leakage of rubber sealing materials with service time under the influence of ultraviolet irradiation effects of different irradiation doses, and the changes in the proportional weight of the two leakage modes;

[0048] Determine the weights of the effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen, and ultraviolet irradiation on the leakage rate and interface leakage rate of rubber sealing materials.

[0049] Furthermore, the variation patterns of leakage rates under the combined effects of the space environment were determined, including:

[0050] By comparing the differences in leakage rate and interface leakage rate of rubber sealing materials under the combined effects of atmospheric pressure-thermal cycling, atmospheric pressure-thermal cycling and vacuum-thermal cycling, the weight of the combined effect of the two space environments is determined compared with that of a single space environment factor.

[0051] By comparing the combined effects of atmospheric pressure-thermal cycling and vacuum-thermal cycling with the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling and atomic oxygen irradiation, the differences in leakage rate and interface leakage rate of rubber sealing materials are determined, and the weight of the influence of the combined effects of the three space environments is determined.

[0052] By comparing the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen irradiation, and the differences in leakage rate and interface leakage rate of rubber sealing materials under the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen irradiation, and ultraviolet irradiation, the weights of the combined effects of the four space environments are determined.

[0053] Furthermore, during the testing process, the constructed rubber sealing material body leakage and interface leakage models were modified to improve the accuracy of test results calculation under single-factor and multi-factor complex spatial environmental effects.

[0054] Furthermore, the leakage rate variation law of the rubber sealing material body leakage under the multi-factor spatial environment effect, and the variation law law of the proportion of the two leakage modes under the multi-factor spatial environment effect, are all discrete points. The least squares method is applied to the above discrete points to form a continuous variation curve, which is the mathematical model for predicting the leakage rate of the rubber sealing material body under the multi-factor spatial environment effect; the leakage rate variation law of the rubber sealing material interface leakage under the multi-factor spatial environment effect, and the variation law law of the proportion of the two leakage modes under the multi-factor spatial environment effect, are all discrete points. The least squares method is applied to the above discrete points to form a continuous variation curve, which is the mathematical model for predicting the interface leakage rate of the rubber sealing material under the multi-factor spatial environment effect.

[0055] Compared with the prior art, the present invention has the following advantages:

[0056] (1) This invention proposes for the first time the concept that the total leakage rate of rubber seals is composed of two leakage modes: leakage of the rubber sealing material body and leakage of the micro interface, thereby improving the calculation accuracy of the leakage rate of rubber seals under the effects of complex spatial environment.

[0057] (2) This invention analyzes the changes in the proportion of two leakage modes of rubber seals under complex space environment effects over time and the law of leakage rate change, establishes the correlation between rubber seal leakage rate and time, realizes the prediction of rubber seal leakage rate under multi-factor space environment effects, and is used to analyze the total leakage rate of rubber seals in spacecraft that are under complex space environment effects for a long time. It can accurately predict the leakage rate of rubber seals in different service periods. Attached Figure Description

[0058] Figure 1 A diagram illustrating the analysis of the evolution mechanism of rubber sealing performance;

[0059] Figure 2 A physical model for seepage analysis of porous media in rubber sealing materials;

[0060] Figure 3 Analysis of the microscopic contact properties of rubber materials;

[0061] Figure 4 The evolution law of rubber sealing performance under the single-factor effect of space environment;

[0062] Figure 5 The percentage of two leakage modes of rubber seals under the single-factor effect of the space environment;

[0063] Figure 6 The evolution law of rubber sealing performance under the comprehensive effect of multiple factors in the space environment;

[0064] Figure 7 The percentage of two leakage modes in rubber seals under the combined effects of multiple factors in the space environment. Detailed Implementation

[0065] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0066] Figure 1 The diagram illustrates the analysis scheme for the evolution mechanism of rubber sealing performance. The method includes the following steps:

[0067] (1) The stress-strain constitutive relationship, thermal expansion coefficient and permeability coefficient of the rubber sealing material under single-factor and multi-factor complex space environment effects were tested respectively, as well as the surface micromorphology of the metal material in contact with the rubber sealing material under single-factor and multi-factor complex space environment effects; during the test, the rubber sealing material was the prepared O-ring rubber seal.

[0068] (2) Construct a leakage model of the rubber sealing material body, and include the permeability coefficient of the rubber sealing material under single-factor and multi-factor complex spatial environment effects into the model respectively, and calculate the leakage rate of the rubber sealing material body under single-factor and multi-factor complex spatial environment effects respectively.

[0069] (3) Establish a theoretical model for macroscopic contact performance analysis of rubber seals. Based on the stress-strain constitutive relationship and thermal expansion coefficient of rubber seal materials under single-factor and multi-factor complex spatial environment effects, calculate the contact pressure and contact width of rubber seals under single-factor and multi-factor complex spatial environment effects respectively.

[0070] (4) Construct a micro-contact performance analysis model for rubber seals, and combine the micro-morphology of metal material surface, rubber seal contact pressure and contact width under single-factor and multi-factor complex spatial environment effects to calculate the leakage rate of rubber seal interface under single-factor and multi-factor complex spatial environment effects respectively.

[0071] (5) Determine the variation law of leakage rate of rubber sealing material body leakage and interface leakage under single factor spatial environment effect, obtain the influence weight of leakage rate of rubber sealing material under single factor spatial environment effect, and the variation law of proportion of the two leakage modes.

[0072] (6) Determine the variation law of leakage rate of two leakage modes, namely body leakage and interface leakage, under the multi-factor space environment effect, and obtain the variation law of the proportion of the two leakage modes under the multi-factor space environment effect.

[0073] (7) Establish mathematical models for predicting the leakage rate of the rubber sealing material body and the interface leakage rate under the multi-factor spatial environment effect, and predict the leakage rate of the rubber sealing material body and the interface leakage rate, as well as the total leakage rate under the multi-factor spatial environment effect; the total leakage rate is the sum of the leakage rates of the two leakage modes of the rubber seal.

[0074] Furthermore, leakage within the rubber sealing material itself and leakage at the interface are two types of leakage.

[0075] Furthermore, the single-factor space environment effect refers to any one of the following: atmospheric pressure-thermal cycling space environment effect, vacuum-thermal cycling space environment effect, atomic oxygen space environment effect with different irradiation doses, and ultraviolet irradiation space environment effect with different irradiation doses; the multi-factor space environment effect refers to any one of the following: the combined space environment effect of atmospheric pressure-thermal cycling and vacuum-thermal cycling; the combined space environment effect of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen irradiation; the combined space environment effect of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen irradiation, and ultraviolet irradiation; the test is conducted in accordance with the product acceptance-level test requirements recommended in aerospace standards.

[0076] Furthermore, the method for calculating the leakage rate of the rubber sealing material body is as follows:

[0077] Based on Darcy's porous media theory, a model for analyzing the bulk leakage rate of rubber sealing materials based on porous media structures is constructed. When modeling, the shape of the rubber sealing material is taken as the shape under compression at a given compression rate. Figure 2 A physical model for seepage analysis of porous media in rubber sealing materials is provided. The compressed rubber sealing material is divided into n sub-regions along the horizontal direction, and the shape of the rubber sealing material corresponding to each sub-region is considered as rectangular. The leakage rate Q of the rubber sealing material body is given. k The calculation formula is:

[0078]

[0079] In the formula, r is the inner diameter of the rubber sealing material; D r v is the cross-sectional diameter of the rubber sealing material; i is the i-th region divided by the leakage rate analysis model of the rubber sealing material; i Let be the fluid velocity at the outlet of the i-th region in the analysis model of the leakage rate of the rubber sealing material body;

[0080] Where v i The calculation formula is:

[0081]

[0082] In the formula, ΔP is the pressure difference between the upstream and downstream sides of the rubber sealing material structure, L is the length of the rubber sealing material structure in the flow direction, μ is the fluid viscosity, and k is the viscosity of the fluid. i Let be the permeability of the i-th region of the rubber seal.

[0083] Furthermore, the macroscopic contact performance analysis theoretical model of rubber seals refers to the finite element model constructed using computer finite element software; the calculation method for the contact pressure and contact width of the rubber sealing material is as follows: in the macroscopic contact performance analysis theoretical model of rubber seals, pressure is applied to the rubber sealing material from top to bottom to deform it, and the stress-strain constitutive relationship and thermal expansion coefficient of the rubber sealing material under single-factor and multi-factor spatial environmental effects are applied to the finite element model, and the contact pressure and contact width of the rubber sealing material under single-factor and multi-factor spatial environmental effects are obtained through finite element calculation.

[0084] Furthermore, the calculation process for the leakage rate at the rubber sealing interface is as follows:

[0085] A computational domain is selected along the circumferential direction at the contact surface of the rubber sealing material. This computational domain is then divided into several sub-regions. The flow conductance calculation method for each sub-region is as follows:

[0086] Based on the microscopic morphology of the metal material surface in contact with the rubber sealing material under single-factor and multi-factor spatial environmental effects, the cross-sectional dimensions of the microscopic leakage channel of the rubber sealing material under single-factor and multi-factor spatial environmental effects are calculated by the rubber sealing microscopic contact performance analysis model.

[0087] The equivalent hydraulic diameter d of the equivalent circular cross-section pipe of the micro-leakage channel of the rubber sealing material is calculated by the formula: d = 4A / l, where A is the cross-sectional area of ​​the micro-leakage channel of the rubber sealing material and l is the perimeter of the cross-section of the micro-leakage channel of the rubber sealing material.

[0088] The flow regime in the leakage channel is determined based on the equivalent hydraulic diameter, and the determination criteria are as follows: It is a viscous flow; It is a molecular flow; It is a viscous-molecular flow; where, The mean free path of gas molecules;

[0089] In viscous flow, the flow conductance U of the equivalent circular cross-section pipe n The calculation formula is as follows:

[0090]

[0091] Where L′ is the pipe length and η is the gas viscosity coefficient. The average pressure in the pipeline. p1 and p2 are the gas pressures at both ends of the equivalent circular cross-section pipe, respectively;

[0092] During molecular flow, the conductance U of the equivalent circular cross-section pipe f The calculation formula is as follows:

[0093]

[0094] Where R is the molar gas constant, 8.3143; M is the molar mass of the gas; T is the temperature; and d is the pipe diameter.

[0095] In viscous-molecular flow, the conductance U of the equivalent circular cross-section pipe n.f The calculation formula is as follows:

[0096]

[0097] Where η is the gas viscosity coefficient. The average pressure in the pipeline. p1 and p2 are the gas pressures at both ends of the pipe, respectively;

[0098] The total conductance of a single radial leakage is obtained by connecting the conductances of each sub-region in series, and then the leakage rate caused by a single radial leakage channel is calculated. The leakage rate caused by a single radial leakage channel is multiplied by the number of radial micro-leakage channels of the rubber sealing material to obtain the leakage rate of the sealing ring interface.

[0099] Furthermore, the variation patterns of leakage rates under two modes—bulk leakage and interfacial leakage—of rubber sealing materials under single-factor spatial environmental effects were determined, including:

[0100] The leakage rate of rubber sealing materials under atmospheric pressure-thermal cycling environment was tested to obtain the variation law of the leakage of the rubber sealing material body and the interface leakage with the number of atmospheric pressure-thermal cycles and time, as well as the change of the ratio weight of the two leakage modes.

[0101] The leakage rate of rubber sealing materials under the vacuum-thermal cycling environment effect was tested to obtain the changes in the leakage of the rubber sealing material body and the interface leakage with the number of vacuum-thermal cycles and time, as well as the changes in the proportion and weight of the two leakage modes.

[0102] Under the same number of thermal cycles and the same high and low temperature environments, the differences in the effects of atmospheric pressure-thermal cycling and vacuum-thermal cycling on the leakage rate of rubber seals were compared to obtain the weights of the effects of the two operating conditions on the leakage rate of rubber seals.

[0103] The leakage rate of rubber seals under different irradiation doses was tested using helium mass spectrometry vacuum leak detection method. The variation law of rubber seal leakage rate with irradiation dose and time under the influence of atomic oxygen effect was obtained. The variation law of rubber seal material leakage and interface leakage with service time under the influence of atomic oxygen effect of different irradiation doses was analyzed, as well as the change of the ratio weight of the two leakage modes.

[0104] Determine the weights of the effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen on the bulk leakage rate and interfacial leakage rate of rubber sealing materials;

[0105] The leakage rate of rubber seals under different irradiation doses was tested using helium mass spectrometry vacuum leak detection method to obtain the variation law of rubber seal leakage rate with irradiation dose and time.

[0106] To determine the changes in leakage and interface leakage of rubber sealing materials with service time under the influence of ultraviolet irradiation effects of different irradiation doses, and the changes in the proportional weight of the two leakage modes;

[0107] Determine the weights of the effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen, and ultraviolet irradiation on the leakage rate and interface leakage rate of rubber sealing materials.

[0108] Furthermore, the variation patterns of leakage rates under the combined effects of the space environment were determined, including:

[0109] By comparing the differences in leakage rate and interface leakage rate of rubber sealing materials under the combined effects of atmospheric pressure-thermal cycling, atmospheric pressure-thermal cycling and vacuum-thermal cycling, the weight of the combined effect of the two space environments is determined compared with that of a single space environment factor.

[0110] By comparing the combined effects of atmospheric pressure-thermal cycling and vacuum-thermal cycling with the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling and atomic oxygen irradiation, the differences in leakage rate and interface leakage rate of rubber sealing materials are determined, and the weight of the influence of the combined effects of the three space environments is determined.

[0111] By comparing the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen irradiation, and the differences in leakage rate and interface leakage rate of rubber sealing materials under the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen irradiation, and ultraviolet irradiation, the weights of the combined effects of the four space environments are determined.

[0112] Furthermore, during the testing process, the constructed rubber sealing material body leakage and interface leakage models were modified to improve the accuracy of test results calculation under single-factor and multi-factor complex spatial environmental effects.

[0113] Furthermore, the leakage rate variation law of the rubber sealing material body leakage under the multi-factor spatial environment effect, and the variation law law of the proportion of the two leakage modes under the multi-factor spatial environment effect, are all discrete points. The least squares method is applied to the above discrete points to form a continuous variation curve, which is the mathematical model for predicting the leakage rate of the rubber sealing material body under the multi-factor spatial environment effect; the leakage rate variation law of the rubber sealing material interface leakage under the multi-factor spatial environment effect, and the variation law law of the proportion of the two leakage modes under the multi-factor spatial environment effect, are all discrete points. The least squares method is applied to the above discrete points to form a continuous variation curve, which is the mathematical model for predicting the interface leakage rate of the rubber sealing material under the multi-factor spatial environment effect.

[0114] Example:

[0115] The following detailed description uses specific embodiments.

[0116] (1) Calculate the leakage rate of the rubber sealing material body and the interface leakage rate.

[0117] 1) Calculate the leakage rate of the rubber sealing material.

[0118] The permeability coefficient of the rubber material calculated by the test is 0.78 (m). 2 / Pa.s(×10 -16 Incorporating this into the porous media model of the constructed rubber sealing material, the calculated leakage rate of the rubber sealing material is 3.2 × 10⁻⁶. -7(Pa.m 3 / s).

[0119] 2) Calculate the leakage rate at the rubber seal interface

[0120] Based on the constructed theoretical model for macroscopic contact performance analysis of rubber seals, the contact pressure and contact width of the rubber seals were calculated. On this basis, surface morphology data of 0.5mm*0.5mm dimensions were extracted from three different locations on the machined end face of the metal material. Rubber material with the same side length and a thickness of 0.1mm was then used to contact these materials. A 2-micrometer-level microscopic finite element contact model of the rubber-metal material was established in Abaqus. This model primarily obtained the state of the rubber embedded in the rough metal surface and the microscopic contact state. The relationship between the applied pressure load and the macroscopic contact stress was then established. Figure 3 As shown.

[0121] Based on the performance analysis results of the macroscopic and microscopic contact of the rubber seal, and the surface microstructure of the tested metal material, the equivalent hydraulic diameter of the microscopic leakage channel was calculated. The flow regime of the fluid in the leakage channel was determined, and the conductance in the microscopic leakage channel under the corresponding flow regime was calculated. The conductances of different leakage channels were calculated in series and parallel, and the leakage rate of the rubber seal was calculated to be 3.2 × 10⁻⁶. -5 (Pa.m 3 / s).

[0122] (2) Calculate the leakage rate of rubber seals under single-factor spatial environmental effects

[0123] This analysis examines the influence and weighting of space environmental factors on rubber sealing performance under two single-factor space environmental effects: atomic oxygen and ultraviolet irradiation. Figure 4 As shown in the figure, with the increase of atomic oxygen accumulation and ultraviolet irradiation, both the bulk leakage rate and interface leakage rate of the rubber sealing material exhibit an evolution trend of initially increasing rapidly and then increasing slowly. This indicates that both of the above-mentioned single-factor spatial environmental effects will increase the mechanical properties and damage degree of the rubber material. In addition, comparing the leakage rate and interface leakage rate of the rubber sealing material under the influence of atomic oxygen and ultraviolet irradiation, it shows that atomic oxygen has a greater impact on both leakage modes of the rubber seal, indicating that the weight of the influence of atomic oxygen on the performance of the rubber seal is greater than that of ultraviolet irradiation.

[0124] The changes in the ratio of bulk leakage to interfacial leakage rate of rubber sealing materials under the single-factor effects of atomic oxygen and ultraviolet irradiation are shown in [reference needed]. Figure 5 The results show that as the amount of atomic oxygen accumulated and the amount of ultraviolet radiation increase, the proportion of leakage and interface leakage in rubber materials also increases.

[0125] (3) Calculate the leakage rate of rubber seals under multi-factor spatial environmental effects.

[0126] To facilitate the comparative analysis of the calculation results, the ultraviolet irradiation, total atomic oxygen irradiation dose, and the number of cycles between atmospheric pressure and high / low temperature and vacuum and high / low temperature were all divided into 9 parts, and classified according to the serial number 0, 1, 2..., 8. The serial number "0" represents the performance of the rubber seal without experiencing the effects of the space environment.

[0127] The evolution law of rubber sealing performance under the influence of multiple factors in space environment is as follows: Figure 6 As shown, the experimental results indicate that compared with the single-factor space environment effect of atomic oxygen or ultraviolet irradiation, the combined effect of ultraviolet irradiation, atomic oxygen, vacuum, and thermal cycling significantly increases the leakage rate of the rubber sealing material and the interface leakage rate. This suggests that the combined effect of multiple factors in the space environment exacerbates the damage to the rubber material and degrades its mechanical properties. Figure 6 The study also showed that as the cumulative effect of multiple spatial environmental factors increased, the leakage rate of both leakage modes of rubber seals exhibited a nonlinear trend of first increasing rapidly and then increasing slowly.

[0128] Figure 7 The figure presents the ratio of the bulk leakage rate to the interfacial leakage rate of the rubber sealing material under the combined effects of multiple factors in the space environment. As can be seen from the figure, the ratio of the two leakage modes increases with the increase of the cumulative effect of the multiple factors. Furthermore, compared with the influence of single-factor space environment effects, the ratio of both leakage modes of the rubber seal increases significantly under the combined effect of multiple factors in the space environment, indicating that complex space environmental factors cause more significant damage to the rubber material itself.

[0129] The error between the leakage rate estimated by the prediction method proposed in this invention and the leakage rate of the rubber seal after experiencing complex spatial environmental effects, as tested by the leak detection test method, is less than 10%, which meets the accuracy requirements.

[0130] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for predicting the leakage rate of rubber seals under complex space environment effects, characterized in that, The steps are as follows: (1) The stress-strain constitutive relationship, thermal expansion coefficient and permeability coefficient of rubber sealing material under single-factor and multi-factor complex space environment effects were tested respectively, as well as the surface micromorphology of metal material in contact with rubber sealing material under single-factor and multi-factor complex space environment effects; The single-factor space environment effect refers to any one of the following: atmospheric pressure-thermal cycling space environment effect, vacuum-thermal cycling space environment effect, atomic oxygen space environment effect with different irradiation doses, and ultraviolet irradiation space environment effect with different irradiation doses; the multi-factor space environment effect refers to any one of the following: the combined space environment effect of atmospheric pressure-thermal cycling and vacuum-thermal cycling; the combined space environment effect of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen irradiation; the combined space environment effect of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen irradiation, and ultraviolet irradiation. (2) Construct a leakage model of the rubber sealing material body, and include the permeability coefficient of the rubber sealing material under single-factor and multi-factor complex spatial environment effects into the model respectively, and calculate the leakage rate of the rubber sealing material body under single-factor and multi-factor complex spatial environment effects respectively. (3) Establish a theoretical model for macroscopic contact performance analysis of rubber seals. Based on the stress-strain constitutive relationship of rubber seal materials under single-factor and multi-factor complex spatial environment effects, calculate the contact pressure and contact width of rubber seals under single-factor and multi-factor complex spatial environment effects respectively. (4) Construct a microscopic contact performance analysis model for rubber seals, and combine the microscopic morphology of metal material surface, rubber seal contact pressure and contact width under single-factor and multi-factor complex spatial environment effects to calculate the leakage rate of rubber seal interface under single-factor and multi-factor complex spatial environment effects respectively. (5) Determine the variation law of leakage rate of rubber sealing material body leakage and interface leakage under single factor spatial environment effect, obtain the influence weight of leakage rate of rubber sealing material under single factor spatial environment effect, and the variation law of proportion of the two leakage modes. (6) Determine the variation law of leakage rate of two leakage modes, namely body leakage and interface leakage, under the multi-factor space environment effect, and obtain the variation law of the proportion of the two leakage modes under the multi-factor space environment effect; (7) Establish mathematical models for predicting the leakage rate of the rubber sealing material body and the interface leakage rate under the multi-factor spatial environment effect, and predict the leakage rate of the rubber sealing material body and the interface leakage rate, as well as the total leakage rate under the multi-factor spatial environment effect; the total leakage rate is the sum of the leakage rates of the two leakage modes of the rubber seal. The specific steps for establishing a mathematical model to predict the leakage rate of rubber sealing materials under multi-factor spatial environmental effects are as follows: the leakage rate variation law of rubber sealing materials under multi-factor spatial environmental effects, and the variation law of the proportion of the two leakage modes under multi-factor spatial environmental effects are both discrete points. The least squares method is applied to fit the above discrete points to form a continuous variation curve. The variation curve is the mathematical model for predicting the leakage rate of rubber sealing materials under multi-factor spatial environmental effects. The specific steps for establishing a mathematical model to predict the leakage rate of rubber sealing material interfaces under multi-factor spatial environmental effects are as follows: the leakage rate variation law of rubber sealing material interface leakage under multi-factor spatial environmental effects, and the variation law law of the proportion of the two leakage modes under multi-factor spatial environmental effects are both discrete points. The least squares method is applied to fit the above discrete points to form a continuous variation curve. The variation curve is the mathematical model for predicting the leakage rate of rubber sealing material interfaces under multi-factor spatial environmental effects.

2. The method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 1, characterized in that: During the test, the rubber sealing material was a prepared O-ring rubber seal.

3. The method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 2, characterized in that: The method for calculating the leakage rate of the rubber sealing material body is as follows: Based on Darcy's porous media theory, a leakage rate analysis model for rubber sealing materials based on porous media structures is constructed. In modeling, the shape of the rubber sealing material is taken as its shape under compression at a given compression rate. The compressed rubber sealing material is divided into n sub-regions along the horizontal direction, and the shape of the rubber sealing material corresponding to each sub-region is considered as a rectangle. The leakage rate of the rubber sealing material is... Q k The calculation formula is: In the formula, r The inner diameter of the rubber sealing material; D r The diameter of the rubber sealing material cross-section; i The i-th region is defined in the analysis model of the leakage rate of the rubber sealing material. v i The first model for analyzing the leakage rate of rubber sealing materials. i The flow rate of the fluid at the outlet of each region; in v i The calculation formula is: In the formula, For the pressure difference between upstream and downstream of the rubber sealing material structure, L The length of the rubber sealing material structure in the flow direction, For fluid viscosity, k i For the rubber sealing ring i The penetration rate of the regional structure.

4. The method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 1, characterized in that: The aforementioned theoretical model for analyzing the macroscopic contact performance of rubber seals refers to a finite element model constructed using computer finite element software. The calculation method for the contact pressure and contact width of the rubber sealing material is as follows: In the theoretical model for analyzing the macroscopic contact performance of rubber seals, pressure is applied to the rubber sealing material from top to bottom to deform it. The stress-strain constitutive relationship and thermal expansion coefficient of the rubber sealing material under single-factor and multi-factor spatial environmental effects are applied to the finite element model. The contact pressure and contact width of the rubber sealing material under single-factor and multi-factor spatial environmental effects are obtained through finite element calculation.

5. The method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 1, characterized in that: The leakage rate calculation process for the rubber sealing interface is as follows: A computational domain is selected along the circumferential direction at the contact surface of the rubber sealing material. This computational domain is then divided into several sub-regions. The flow conductance calculation method for each sub-region is as follows: Based on the microscopic morphology of the metal material surface in contact with the rubber sealing material under single-factor and multi-factor spatial environmental effects, the cross-sectional dimensions of the microscopic leakage channel of the rubber sealing material under single-factor and multi-factor spatial environmental effects are calculated by the rubber sealing microscopic contact performance analysis model. Calculate the equivalent hydraulic diameter of the pipe with the equivalent circular cross-section for the microscopic leakage channels of the rubber sealing material. d The calculation formula is: d =4 A / l ,in A This represents the cross-sectional area of ​​the microscopic leakage channel in the rubber sealing material. l The perimeter of the cross-section of the microscopic leakage channel in the rubber sealing material; The flow regime in the leakage channel is determined based on the equivalent hydraulic diameter, and the determination criteria are as follows: It is a viscous flow; It is a molecular flow; It is a viscous-molecular flow; where, The mean free path of gas molecules; In viscous flow, the flow conductance of an equivalent circular cross-section pipe The calculation formula is as follows: in, For the length of the pipe, The viscosity coefficient of the gas. The average pressure in the pipeline. , p 1, p 2 represents the gas pressure at both ends of the equivalent circular cross-section pipe; In molecular flow, the conductance of an equivalent circular cross-section pipe The calculation formula is as follows: in, R is the molar gas constant, 8.3143; M The molar mass of the gas; T For temperature; d The diameter of the pipe; Conductivity of an equivalent circular cross-section pipe during viscous molecular flow The calculation formula is as follows: in, The viscosity coefficient of the gas. The average pressure in the pipeline. , p 1, p 2 represents the gas pressure at both ends of the pipeline; The total conductance of a single radial leakage is obtained by connecting the conductances of each sub-region in series, and then the leakage rate caused by a single radial leakage channel is calculated. The leakage rate caused by a single radial leakage channel is multiplied by the number of radial micro-leakage channels of the rubber sealing material to obtain the leakage rate of the rubber sealing interface.

6. The method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 1, characterized in that: The determination of the variation law of leakage rate of rubber sealing material under two modes of leakage, namely bulk leakage and interface leakage, under single-factor spatial environmental effects includes: The leakage rate of rubber sealing materials under atmospheric pressure-thermal cycling environment was tested to obtain the variation law of the leakage of the rubber sealing material body and the interface leakage with the number of atmospheric pressure-thermal cycles and time, as well as the change of the ratio weight of the two leakage modes. The leakage rate of rubber sealing materials under the vacuum-thermal cycling environment effect was tested to obtain the changes in the leakage of the rubber sealing material body and the interface leakage with the number of vacuum-thermal cycles and time, as well as the changes in the proportion and weight of the two leakage modes. The leakage rate of rubber seals under different irradiation doses was tested using helium mass spectrometry vacuum leak detection method. The variation law of rubber seal leakage rate with irradiation dose and time under the influence of atomic oxygen effect was obtained. The variation law of rubber seal material leakage and interface leakage with service time under the influence of atomic oxygen effect of different irradiation doses was analyzed, as well as the change of the ratio weight of the two leakage modes. The leakage rate of rubber seals under different irradiation doses was tested using helium mass spectrometry vacuum leak detection method to obtain the variation law of rubber seal leakage rate with irradiation dose and time. To determine the changes in leakage and interface leakage of rubber sealing materials with increasing service time under the influence of ultraviolet irradiation effects of different irradiation doses, as well as the changes in the proportional weights of the two leakage modes.

7. The method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 1, characterized in that: The determination of the variation law of leakage rate under the two modes of body leakage and interface leakage of rubber sealing material under the comprehensive space environment effect includes: By comparing the differences in leakage rate and interface leakage rate of rubber sealing materials under the combined effects of atmospheric pressure-thermal cycling, atmospheric pressure-thermal cycling and vacuum-thermal cycling, the weight of the combined effect of the two space environments is determined compared with that of a single space environment factor. By comparing the combined effects of atmospheric pressure-thermal cycling and vacuum-thermal cycling with the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling and atomic oxygen irradiation, the differences in leakage rate and interface leakage rate of rubber sealing materials are determined, and the weight of the influence of the combined effects of the three space environments is determined. By comparing the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, and atomic oxygen irradiation, and the differences in leakage rate and interface leakage rate of rubber sealing materials under the combined effects of atmospheric pressure-thermal cycling, vacuum-thermal cycling, atomic oxygen irradiation, and ultraviolet irradiation, the weights of the combined effects of the four space environments are determined.

8. A method for predicting the leakage rate of rubber seals under complex space environment effects according to claim 6 or 7, characterized in that: During the testing process, the calculation accuracy of test results under single-factor and multi-factor complex spatial environmental effects was improved, and the constructed rubber sealing material body leakage and interface leakage models were corrected.

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