An evaluation device and method for the degree of attenuation of the high-temperature sealing performance of a seal

Abstract

The application discloses a kind of sealing high temperature sealing performance attenuation degree evaluation device and method, belong to composite material quality evaluation, high temperature sealing field, the device includes upper pressure head, lower fixture, force sensor, flame gun, baffle and thermocouple;The steps of the method include installing seal, using flame gun to make seal sample burn, establish the functional relationship between seal compression force and back fire side temperature, establish the correlation model between seal structure-compression force-high temperature sealing performance in the whole combustion process, to quantitatively evaluate the attenuation degree of sealing performance of seal.The application can more truly simulate the actual service condition of seal by in-situ experiment in actual high temperature, pressure head compression, pressure difference environment, accurately reflect the sealing performance attenuation condition of seal under high temperature condition, overcome the deficiency that actual service condition cannot be simulated in prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of composite material quality evaluation and high-temperature sealing, and particularly relates to a device and method for evaluating the attenuation degree of high-temperature sealing performance of a sealing element. BACKGROUND

[0002] Sealing elements are widely used in aerospace, energy, transportation and other fields. In the aerospace field, sealing elements are widely used in aircraft engine compartments, auxiliary power unit (APU) compartment doors, fuel systems, short-hull hangers and other high-temperature environments. These components are exposed to extreme high temperatures, pressure changes and flames, and fireproof sealing elements must ensure sealing performance at high temperatures to prevent the spread of fire and protect aircraft structures and passengers. In energy facilities, fireproof sealing elements are commonly used in oil and gas pipelines and power stations to seal high-temperature pipelines, valves and equipment joints. These devices are prone to exposure to high temperatures and fire risks, and fireproof sealing elements can effectively block the spread of flames and harmful gases to prevent catastrophic accidents. In the transportation field, fireproof sealing elements are used in engine compartments, exhaust systems, car body walls and other high-temperature or high-fire-risk areas. In particular, in high-speed and subway trains, fireproof sealing elements need to control the spread of flames when a fire occurs and provide necessary thermal insulation to ensure the safety of passengers and equipment. In these environments, sealing elements not only need to withstand vibration, pressure difference and other conventional working conditions, but also need to withstand the direct action of extreme temperatures, and the reliability of their performance is directly related to the safety of the device structure and personal safety.

[0003] After compression, sealing elements rely on contact forces to tightly contact other metal structures, filling gaps in the structure and blocking leakage channels. After burning, the material properties of the sealing element change significantly, such as thermal degradation of rubber and loss of strength of fiber reinforcement, leading to attenuation of high-temperature sealing performance. If the degree of this attenuation cannot be accurately evaluated, it is difficult to predict the service life and failure risk of the sealing element, which may lead to a failure to replace or maintain it in time and pose a safety hazard. Therefore, evaluating the degree of attenuation of fireproof sealing performance after burning is of great significance to ensure the reliable operation of aircrafts under extreme conditions, extend their service life, and develop reasonable maintenance strategies. In the fields of aerospace, energy, transportation and other high-reliability and high-safety requirements, the lack of quantitative analysis of the attenuation of sealing performance of sealing elements under high-temperature conditions not only limits the development of sealing element design, but also poses a hidden danger to the overall structural safety. Therefore, it is particularly important to propose a method and system that can quantitatively evaluate the attenuation of sealing performance of sealing elements under high-temperature conditions. SUMMARY

[0004] In view of the problems existing in the current evaluation method of high-temperature sealing performance of a sealing element, the application provides an evaluation device and method for the attenuation degree of high-temperature sealing performance of a sealing element, which extracts the compression force and backfire side temperature of a sealing element sample at different combustion degrees through in-situ experiment, establishes the connection between the mechanical properties and high-temperature sealing characteristics under actual service conditions by fitting the functional relationship between the compression force and the backfire side temperature, takes the compression force as the key parameter for evaluating the attenuation degree of sealing performance, and establishes the correlation model of the compression force and material and structure parameters of the sealing element in the whole combustion process, so as to realize the quantitative evaluation of the attenuation of high-temperature sealing performance of the sealing element.

[0005] To this end, the technical solution of the application is as follows:

[0006] An evaluation device for the attenuation degree of high-temperature sealing performance of a sealing element, comprising an upper press head, a lower clamp, a force sensor, a flame gun, a baffle and a thermocouple.

[0007] The upper press head and the lower clamp are respectively arranged on the upper side and the lower side of the sealing element to be measured, the compression of the sealing element is realized by the downward pressing of the upper press head, the force sensor is arranged below the sealing element to be measured for measuring the compression force, the flame gun is used to make the sealing element to be measured burn, the baffle is arranged on the side of the sealing element to be measured away from the flame gun, and the thermocouple is arranged on the surface of the sealing element to be measured away from the flame gun for measuring the backfire side temperature.

[0008] An evaluation method for the attenuation degree of high-temperature sealing performance of a sealing element, comprising the following steps:

[0009] Step S1, installing a sealing element, placing the sealing element on the above-mentioned evaluation device, pressing the upper press head downward by a certain compression amount d, inflating the sealed cavity isolated after the compression of the sealing element, and stopping until the actual service pressure.

[0010] Step S2, burning the sealing element sample using the flame gun, and recording the compression force and the backfire side temperature of the sealing element at different combustion times.

[0011] Step S3, fitting the relationship between the compression force and the backfire side temperature of the in-situ experiment, and establishing the functional relationship between the compression force and the backfire side temperature of the sealing element.

[0012] Step S4, quantitative evaluation of the attenuation of sealing performance of the sealing element, establishing the correlation model between the structure of the sealing element, the compression force and the high-temperature sealing performance in the whole combustion process according to the compression force of the sample at different combustion degrees, so as to quantitatively evaluate the attenuation degree of the sealing performance of the sealing element.

[0013] Compression force refers to the force generated inside an object to resist external compression load. For a seal, compression force usually refers to the counterforce generated by the seal when it is compressed, which determines whether the seal can effectively fill the sealing interface and prevent gas or liquid leakage in a compressed state. Proper compression force can ensure that the seal closely fits the contact surface to form an effective seal. In a high-temperature environment, the composite material will soften and decompose, resulting in a decrease in compression force, which causes the seal to fail to closely fit the contact surface, resulting in gas leakage and an increase in backfire side temperature. Therefore, the change in compression force can be used to evaluate the performance degradation of the seal in extreme environments.

[0014] By establishing an accurate quantitative model of the correlation between compression force and backfire side temperature through in-situ experiments, the degradation mechanism of rubber seals in high-temperature environments can be deeply understood, and the performance degradation law of the seals in different combustion stages can be revealed. This method can break through the limitations of traditional evaluation methods and provide a scientific and practical performance prediction tool for high-temperature performance evaluation of seals. Not only can the durability of the seal be quickly and accurately evaluated, but data support can also be provided for the design and material selection of the seal, thereby improving the reliability and service life of the seal in extreme working conditions.

[0015] When the seal encounters flame impact, the composite material will soften and decompose, resulting in a decrease in compression force over time until it reaches a plateau, indicating that the combustion process is complete. Compression force is closely related to the material and structure of the seal, and through compression force as a bridge, this model can be used to evaluate the influence of different material structures on high-temperature sealing performance, and to quantify the degree of degradation of the high-temperature sealing performance of the seal.

[0016] In the above technical solution, in step S1, during installation of the seal, the shape of the compression head of the compression test tool is determined by the actual service conditions and can be flat or T-shaped. The compression amount d of the compression head is in the range of 10%-70% of the height of the seal. Inflation refers to pressure reduction by air extraction or pressure increase by air injection, which is determined by the pressure difference on both sides of the sealing surface of the seal in actual service conditions.

[0017] In the above technical solution, in step S2, during combustion of the seal sample, the combustion test environment refers to a temperature box or direct flame impact. The compression force of the seal before compression is zero, and there is a certain initial compression force F0 after compression.

[0018] In the above technical solution, in step S3, the relationship between the compression force and the backfire side temperature of the in-situ experiment is fitted, and the fitting function used is a monotonically decreasing function. Monotonic decrease refers to the increase of the backfire side temperature with the decrease of the compression force, which reflects the quantitative relationship between the compression force and the high-temperature sealing performance degradation.

[0019] In the above technical solution, in step S4, the quantitative evaluation of the sealing performance attenuation of the sealing element, the entire combustion process of the sealing element is the process of the sealing element starting from the initial state of high-temperature sealing performance and gradually attenuating until the sealing element completely loses the high-temperature sealing ability, or the compression force of the sealing element no longer significantly decreases, that is, reaches the plateau state. The sealing element structure refers to the geometric configuration of the sealing element, including π-shaped, Ω-shaped, P-shaped, etc., and the material refers to the elastic modulus of the sealing element.

[0020] To accurately evaluate the sealing performance attenuation of the sealing element in the combustion process, the sealing element compression force data at different combustion times is obtained through in-situ experiments in the present application. In order to establish the quantitative relationship between the compression force and the backfire side temperature, the experimental data is analyzed by fitting. The selection of the fitting function is based on the characteristics of the experimental data and the performance change trend of the sealing element in the combustion process. In the present application, a plurality of mathematical models such as linear function, exponential function, polynomial function, etc. are selected to fit the experimental data respectively, and finally the model with the best fitting effect is selected as the relationship model of the compression force and the backfire side temperature.

[0021] By comparing the fitting degrees (R² values) of different fitting functions, the most suitable fitting model is determined. The closer the R² value is to 1, the better the fitting function can describe the change trend of the experimental data. For example, the relationship between the compression force F and the backfire side temperature T conforms to the quadratic polynomial fitting function, that is, where y is the compression force F, x is the backfire side temperature T, and a, b, c are constants. The function shows that in the early stage of combustion, the compression force of the sealing element gradually decreases with the increase of the combustion time, and in the later stage of combustion, the performance attenuation rate gradually slows down, and finally reaches a stable state. In the fitting process, the experimental data is analyzed by regression analysis through the least square method to solve the parameters a, b, c in the fitting function. The parameter a represents the initial compression force F0 of the sealing element at the beginning of combustion; the parameter b reflects the trend that the compression force of the sealing element gradually attenuates with the increase of the combustion time; and the parameter c represents the change of the compression force attenuation rate in the combustion process.

[0022] The compression force is related to the structure and material performance of the sealing element, so the quantitative model of the compression force of the sealing element is proposed as: where F is the compression force of the in-situ experiment, t is the combustion time, E is the elastic modulus of the material, L is the length of the sealing element, d is the compression amount of the pressure head, C is related to the flame coefficient, the shape of the flame during combustion, and the temperature of the flame nozzle, k is the shape coefficient of the sealing element, which is related to the design shape of the fireproof sealing element, and the elastic modulus will attenuate with the different combustion degrees of the sealing element. Through this quantitative formula, the influence of the material and structure on the compression force can be evaluated, and the relationship between the material and structure parameters, the compression force, and the high-temperature sealing performance is established, so as to evaluate the attenuation degree of the high-temperature sealing performance and the good or bad of the high-temperature sealing performance of the sealing element with different structures.

[0023] The present application has the following beneficial effects:

[0024] (1) The present application can more realistically simulate the actual service condition of the sealing element, accurately reflect the sealing performance decay condition of the sealing element under high temperature condition, and overcome the deficiency of the prior art that cannot simulate the actual service condition by conducting in-situ experiment under actual high temperature, head compression, and pressure difference environment.

[0025] (2) By introducing quantitative analysis between the compression force and the backfire side temperature, the present application can accurately evaluate the performance decay degree and the remaining life of the sealing element, provide reliable quantitative index, and overcome the limitation of the prior art that can only make pass / fail judgment.

[0026] (3) The present application greatly shortens the test cycle, reduces the cost, and speeds up the product development progress by optimizing the experimental process and data processing method. The quantitative method based on physical parameters reduces the subjectivity of human judgment, ensures the consistency and reliability of the experimental results, and overcomes the problems of time-consuming test, high cost, and dependence on subjective judgment in the prior art.

[0027] (4) The present application not only focuses on the performance result of the sealing element under high temperature, but also builds the relationship between the material, structure parameter, compression force, and high temperature sealing performance by monitoring the compression force change in real time, thereby evaluating the decay degree of the high temperature sealing performance and the good or bad of the high temperature sealing performance of different structure sealing elements. The present application reveals the high temperature degradation process and failure mode of the sealing element, provides more in-depth degradation mechanism analysis, helps the iterative optimization of design, and overcomes the deficiency of the prior art that lacks degradation mechanism analysis. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flow chart of the sealing element high temperature sealing performance decay degree evaluation method of the present application is shown in FIG. 1.

[0029] Figure 2 The schematic diagram of the experimental device in the embodiment of the present application is shown in FIG. 2.

[0030] Figure 3 The installation schematic diagram of the Ω-shaped sealing element in the embodiment of the present application is shown in FIG. 3.

[0031] Figure 4 The curve of the compression force and the backfire side temperature in the embodiment of the present application is shown in FIG. 4.

[0032] Figure 5 The curve of the compression force and the combustion time in the embodiment of the present application is shown in FIG. 5.

[0033] In the figure, 1 is an upper head, 2 is a sealing element, 3 is a thermocouple, 4 is a baffle, 5 is a force sensor, 6 is a flame gun, and 7 is a lower clamp. DETAILED DESCRIPTION

[0034] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical methods in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0035] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship between the components, the movement, etc. in a certain posture, and if the certain posture changes, the directional indications will also change accordingly.

[0036] Embodiments

[0037] As shown in Figure 2 and Figure 3 , an aviation silicone rubber seal is selected. First, the Ω-shaped aviation silicone rubber seal to be tested is cut into a sample with a length of 100 mm. The seal is installed on a compression testing machine, which includes an upper compression head 1, a lower clamp 7, a force sensor 5, a flame gun 6, a baffle 4 and a thermocouple 3. The upper compression head 1 and the lower clamp 7 are respectively arranged on the upper side and the lower side of the seal 2 to be tested. The compression of the seal 2 is realized by the downward compression of the upper compression head 1. The force sensor 5 is arranged below the seal 2 to be tested for measuring the compression force. The flame gun 6 is used to cause the seal 2 to be tested to burn. The baffle 4 is arranged on the side of the seal 2 to be tested away from the flame gun 6. The thermocouple 3 is arranged on the surface of the seal 2 to be tested away from the flame gun 6 for measuring the temperature on the backfire side. The compression head is a flat plate. The compression amount of the downward compression of the compression head is 60% of the inner diameter of the seal. The initial compression force F0 of the seal after compression is recorded. Three thermocouples are attached to the backfire side of the seal for detecting the temperature. The seal cavity is pumped to the service pressure.

[0038] As shown in Figure 1 , according to the test procedure, the sample is placed in a combustion test device simulating the actual working condition. The combustion of the aircraft in the high-temperature fire environment is simulated. The butane flame gun is ignited and kept stationary 50 mm in front of the seal tool. The in-situ high-temperature combustion experiment is carried out for 15 minutes. The changing compression force and backfire side temperature during the combustion process are recorded. The results are shown in Figure 4 .

[0039] The relationship between the compression force and the backfire side temperature of the in-situ experiment is fitted, and the compression force data corresponding to the backfire side temperature under the actual service condition are used to establish a correlation model between the high-temperature sealing performance and the compression force of the rubber seal during the entire combustion process. According to the experimental data, linear function, exponential function, polynomial function, etc. are selected to fit the experimental data respectively. By comparing the goodness of fit R² values of different fitting functions, it is found that the R² value of the polynomial function is closest to 1, and the polynomial function model is selected as the relationship model of the compression force and the backfire side temperature, that is, , y is the compression force F, x is the backfire side temperature T, the constant a is positive, and b is negative. The parameter a represents the initial compression force F0 of the seal at the beginning of combustion; the parameter b is negative, which reflects the trend that the compression force of the seal gradually decays with the increase of the backfire side temperature; and the parameter c represents the change of the compression force decay rate during the combustion process. Through this function model, the relationship between the high-temperature sealing performance and the mechanical properties of the seal can be quantified.

[0040] The compression force changes with time in the high-temperature in-situ experiment, and the compression force is related to the material and structural performance of the seal, as shown in Figure 5 The quantitative model of the compression force of the seal and the material and structure proposed in the embodiment is:

[0041] ;

[0042] Wherein, F is the compression force of the in-situ experiment, t is the combustion time, E is the elastic modulus of the material, L is the length of the seal, d is the compression amount of the pressure head, C is related to the flame coefficient, the shape of the flame during combustion, and the temperature of the flame nozzle, k is the shape coefficient related to the design shape of the fireproof seal.

[0043] Up to now, the relationship between the material structure parameters, the compression force and the high-temperature sealing performance has been built through the compression force of the seal, so that the decay degree of the high-temperature sealing performance of the seal and the good or bad of the high-temperature sealing performance of the different structure seals can be quantitatively evaluated.

[0044] The specific embodiments of the application are described in detail above, but as an example, the application is not limited to the specific embodiments described above. Any equivalent modification or alternative to the application made by those skilled in the art is also within the scope of the application, therefore, equivalent transformations, modifications, improvements, etc. made without departing from the spirit and principle range of the application should be covered within the scope of the application.

Claims

1. A device for evaluating the degree of attenuation of high-temperature sealing performance of a seal, characterized by: Includes upper pressure head, lower fixture, force sensor, flame gun, baffle and thermocouple; The upper pressure head and the lower clamp are respectively arranged on the upper and lower sides of the seal to be tested. The seal is compressed by the downward pressure of the upper pressure head. The force sensor is arranged below the test seal to measure the compression force. The flamethrower is used to burn the test seal. The baffle is arranged on the side of the test seal away from the flamethrower. The thermocouple is arranged on the surface of the test seal away from the flamethrower to measure the back-fire side temperature.

2. A method for evaluating the degree of attenuation of high-temperature sealing performance of a seal, characterized in that: The steps include: Step S1, installing the seal, placing the seal on the evaluation device as claimed in claim 1, pressing the upper pressure head downward by a compression amount d, and inflating the sealed cavity isolated by the compression of the seal until it reaches the actual service pressure; Step S2, using a flamethrower to burn the seal sample, and recording the compression force and the back-fire side temperature of the seal at different burning times; Step S3, fitting the relationship between the compression force and the back-fire side temperature of the in-situ experiment to establish a functional relationship between the compression force of the seal and the back-fire side temperature; Step S4, quantitative evaluation of the sealing performance attenuation of the seal, based on the compression force of samples with different combustion degrees, establishes a correlation model between the seal structure-compression force-high temperature sealing performance during the entire combustion process, and quantitatively evaluates the degree of attenuation of the sealing performance of the seal.

3. The method for evaluating the degree of attenuation of high-temperature sealing performance of a seal according to claim 2, characterized in that: In step S1, the range of the compression amount d of the upper pressure head is 10%-70% of the height of the sealing member.

4. The method for evaluating the degree of attenuation of high-temperature sealing performance of a seal according to claim 2, characterized in that: In step S3, the relationship between the compression force and the back-fire side temperature of the in-situ experiment is fitted, and the fitting function adopted is a monotonically decreasing function, in which the back-fire side temperature increases as the compression force decreases.

5. The method for evaluating the degree of attenuation of high-temperature sealing performance of a seal according to claim 2, characterized in that: In step S3, the functional relationship between the sealing member compression force and the back-fire side temperature is: ， Among them, y is the compression force F, x is the back-fire side temperature T, and a, b, and c are constants. During the fitting process, the experimental data were regressed and analyzed by the least squares method to solve the parameters a, b, and c in the fitting function. Parameter a represents the initial compression force F0 of the seal at the beginning of combustion; parameter b represents the trend of the seal compression force gradually decaying with increasing combustion time; and parameter c represents the change in the compression force decay rate during the combustion process.

6. The method for evaluating the degree of attenuation of high-temperature sealing performance of a seal according to claim 2, characterized in that: In step S4 , the seal structure is a geometric configuration of the seal, including a π shape, an Ω shape, or a P shape.

7. The method for evaluating the degree of attenuation of high-temperature sealing performance of a seal according to claim 2, characterized in that: In step S4, the association model is , where F is the compression force of the in-situ test, t is the burning time, E is the elastic modulus of the material, L is the length of the seal, d is the compression of the pressure head, C is the flame coefficient, and k is the shape coefficient of the seal.

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