Device and method for evaluating high-temperature sealing performance attenuation degree of sealing element

Abstract

The invention discloses a device and method for evaluating the high-temperature sealing performance attenuation degree of a sealing element, and belongs to the field of composite material quality evaluation and high-temperature sealing. The device comprises an upper pressure head, a lower clamp, a force sensor, a flame gun, a baffle and a thermocouple; the method comprises the following steps: installing the sealing element, combusting a sealing element sample by using a flame gun, establishing a function relationship between the compression force of the sealing element and the temperature of the back fire side, and establishing a correlation model among the structure, the compression force and the high-temperature sealing performance of the sealing element in the whole combustion process, so as to quantitatively evaluate the attenuation degree of the sealing performance of the sealing element. According to the invention, the in-situ experiment is carried out under the actual high-temperature, pressure head compression and pressure difference environments, so that the actual service condition of the sealing element can be simulated more truly, the sealing performance attenuation condition of the sealing element under the high-temperature condition is accurately reflected, and the defect that the actual service condition cannot be simulated in the prior art is overcome.

Description

Technical Field

[0001] The invention belongs to the field of composite material quality evaluation and high-temperature sealing, and specifically relates to a device and method for evaluating the attenuation degree of high-temperature sealing performance of a seal. Background Art

[0002] Seals are widely used in aerospace, energy, transportation and other fields. Especially in the aerospace field, seals are widely used in high temperature environments such as aircraft engine compartments, auxiliary power unit (APU) doors, fuel systems, nacelle suspensions, etc. These components are exposed to extreme high temperatures, pressure changes and flame exposure. Fireproof seals must ensure that the sealing performance is maintained at high temperatures to prevent the spread of fire and protect the aircraft structure and passenger safety. In energy facilities, fireproof seals are commonly found in oil and gas pipelines and power stations, and are used to seal high-temperature pipes, valves and equipment joints. These equipment are easily exposed to high temperatures and fire risks. Fireproof seals can effectively block the spread of flames and harmful gases to avoid catastrophic accidents. In the transportation field, fireproof seals are used in engine compartments, exhaust systems, car walls and other areas with high temperatures or high fire risks. Especially in high-speed railways and subways, fireproof seals need to ensure that the spread of flames is controlled when a fire occurs, provide the necessary insulation function, and ensure the safety of passengers and equipment. In these environments, seals not only need to withstand conventional working conditions such as vibration and pressure difference, but also need to withstand the direct effects of extreme temperatures. The reliability of their performance is directly related to the structural safety of the equipment and personal safety.

[0003] After compression, the seal relies on contact force to closely contact other metal structures, filling the structural gaps and blocking the leakage channel. After combustion, the material properties of the seal will change significantly, such as thermal degradation of rubber and strength loss of fiber reinforcement, resulting in the attenuation of high-temperature sealing performance. If the degree of attenuation cannot be accurately evaluated, it is difficult to predict the service life and failure risk of the seal, which may lead to the failure to replace or maintain it in time, burying safety hazards. Therefore, evaluating the attenuation degree of fireproof sealing performance after combustion is of great significance to ensure the reliable operation of aircraft under extreme conditions, extend its service life, and formulate reasonable maintenance strategies. In fields with high reliability and high safety requirements such as aerospace, energy, and transportation, the lack of quantitative analysis of the attenuation of sealing performance of seals under high temperature conditions not only limits the development of seal design, but also buries hidden dangers 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 seals under high temperature conditions. Summary of the invention

[0004] In response to the problems existing in the current evaluation method of the high-temperature sealing performance of seals, the present invention provides a device and method for evaluating the degree of attenuation of the high-temperature sealing performance of seals, which extracts the compression force and back-fire side temperature of the seal sample under different combustion degrees at different times through in-situ experiments, and establishes the relationship between mechanical properties and high-temperature sealing characteristics under actual service conditions by fitting the functional relationship between the compression force and the back-fire side temperature. The compression force is used as the key parameter for evaluating the degree of attenuation of the sealing performance, and a correlation model between the compression force and the material and structural parameters of the seal during the entire combustion process is established, thereby achieving rapid and accurate quantitative evaluation of the high-temperature sealing performance attenuation of the seal.

[0005] To this end, the technical solution adopted by the present invention is as follows: A device for evaluating the degree of attenuation of high-temperature sealing performance of a sealing component, comprising an upper pressure head, a lower clamp, a force sensor, a flamethrower, a baffle and a thermocouple; The upper pressure head and the lower clamp are respectively arranged on the upper side and the lower side of the seal to be tested, and the seal is compressed by the downward pressure of the upper pressure head. The force sensor is placed under 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.

[0006] A method for evaluating the degree of attenuation of high-temperature sealing performance of a seal comprises the following steps: Step S1, installing the seal, placing the seal on the above-mentioned evaluation device, pressing the upper pressure head downward by a certain compression amount d, and inflating the sealed cavity isolated after the seal is compressed until it reaches the actual service air pressure.

[0007] Step S2, using a flamethrower to burn the sealing member sample, and recording the compression force and the back-fire side temperature of the sealing member at different burning times.

[0008] Step S3, fitting the relationship between the compression force and the back-fire side temperature of the in-situ experiment, and establishing a functional relationship between the compression force of the seal and the back-fire side temperature.

[0009] Step S4, quantitative evaluation of the attenuation of the sealing performance of the seal, based on the compression force of the samples with different combustion degrees, establishes a correlation model between the seal structure-compression force-high temperature sealing performance during the entire combustion process, so as to quantitatively evaluate the attenuation degree of the sealing performance of the seal.

[0010] Compression force refers to the resistance force generated inside an object when it is subjected to an external compressive load. For seals, compression force usually refers to the reaction force generated by the seal when it is under pressure. This force determines whether the seal can effectively fill the sealing interface under compression to prevent gas or liquid leakage. Appropriate compression force can ensure that the seal fits tightly with its contact surface to form an effective seal. In a high temperature environment, the composite material will soften and decompose, resulting in a weakening of the compression force, causing the seal to be unable to fit tightly with the contact surface, causing gas leakage and an increase in the temperature on the back-fire side. Therefore, changes in compression force can be used to evaluate the performance degradation of seals in extreme environments.

[0011] By establishing an accurate quantitative model of the compression force-back-fire side temperature relationship through in-situ experiments, we can gain in-depth insights into the degradation mechanism of rubber seals in high-temperature environments and reveal the law of performance attenuation at different combustion stages. This method can break through the limitations of traditional evaluation methods and provide a scientific and practical performance prediction tool for the high-temperature performance evaluation of seals. It can not only quickly and accurately evaluate the durability of seals, but also provide data support for the design and material selection of seals, thereby improving the reliability and service life of seals under extreme working conditions.

[0012] When the seal encounters flame impact, the composite material softens and decomposes, causing the compression force to decrease over time until it reaches a plateau, indicating that the combustion process is complete. The compression force is closely related to the material and structure of the seal. Using the compression force as a bridge, the model can be used to evaluate the impact of different material structures on high-temperature sealing performance, and then quantify the degree of attenuation of the high-temperature sealing performance of the seal.

[0013] In the above technical solution, in step S1, when installing the seal, the shape of the pressure head of the compression test tooling is determined by the actual service conditions, and can be a flat plate or a T-shaped one. The value range of the pressure head's downward compression amount d is 10%-70% of the seal height. Inflation refers to vacuuming or pressurizing, which is determined by the pressure difference on both sides of the sealing surface of the seal under actual service conditions.

[0014] In the above technical solution, in step S2, during the combustion of the seal sample, the combustion test environment refers to a temperature box or direct flame impact. The compression force of the seal is zero when not compressed, and there is a certain initial compression force F0 after compression.

[0015] In the above technical solution, step S3 fits the relationship between the compression force and the back-fire side temperature of the in-situ experiment, and the fitting function adopted is a monotonically decreasing function. Monotonically decreasing means that the back-fire side temperature increases as the compression force decreases, reflecting the quantitative relationship between the attenuation of the compression force and the attenuation of high-temperature sealing.

[0016] In the above technical solution, step S4 is a quantitative evaluation of the attenuation of the sealing performance of the seal. The entire combustion process of the seal is a process in which the seal starts to attenuate from the initial high-temperature sealing performance until the seal completely loses its high-temperature sealing ability, or its compression force no longer decreases significantly, that is, reaches a plateau state. The seal structure refers to the geometric configuration of the seal, including π-shaped, Ω-shaped, P-shaped, etc., and the material refers to the elastic modulus of the seal.

[0017] In order to accurately evaluate the attenuation of the sealing performance of the seal during the combustion process, the present invention obtains the compression force data of the seal at different combustion times through in-situ experiments. In order to establish a quantitative relationship between the compression force and the back-fire side temperature, these experimental data are fitted and analyzed. The selection of the fitting function is based on the characteristics of the experimental data and the performance change trend of the seal during the combustion process. In the present invention, a variety of mathematical models are selected, such as linear functions, exponential functions, polynomial functions, etc., to fit the experimental data respectively, and finally the model with the best fitting effect is selected as the relationship model between the compression force and the back-fire side temperature.

[0018] By comparing the goodness of fit (R² value) 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 changing trend of the experimental data. For example, the relationship between the compression force F and the back-fire side temperature T conforms to the quadratic polynomial fitting function, that is, , where y is the compression force F, x is the back-fire side temperature T, and a, b, and c are constants. This function shows that in the early stage of combustion, the compression force of the seal gradually decreases with the increase of combustion time, while in the later stage of combustion, the performance decay rate gradually slows down and finally reaches a stable state. 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 reflects the trend of the compression force of the seal gradually decaying with the increase of combustion time; parameter c represents the change of the compression force decay rate during the combustion process.

[0019] The compression force is related to the structure and material properties of the seal, so the quantitative model of the seal compression force is proposed as follows: , where F is the compression force of the in-situ experiment, 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 related to the flame coefficient, which is related to the shape of the flame during combustion and the temperature of the flame nozzle, and k is the seal shape coefficient, which is related to the design shape of the fireproof seal. The elastic modulus will decay with the different burning degrees of the seal. This quantitative formula can be used to evaluate the influence of materials and structures on the compression force, and to establish the relationship between materials, structural parameters, compression force, and high-temperature sealing performance, so as to evaluate the degree of attenuation of high-temperature sealing performance and the quality of high-temperature sealing performance of seals with different structures.

[0020] The beneficial effects of the present invention are as follows: (1) The present invention can more realistically simulate the actual service conditions of the seal by conducting in-situ experiments under actual high temperature, pressure head compression, and pressure difference environments, and accurately reflect the attenuation of the sealing performance of the seal under high temperature conditions, thereby overcoming the deficiency of the prior art that it cannot simulate the actual service conditions.

[0021] (2) By introducing the quantitative analysis between the compression force and the back-fire side temperature, the present invention can accurately evaluate the performance degradation degree and the remaining life of the seal, provide reliable quantitative indicators, and overcome the limitation of the prior art that only qualification judgment can be performed.

[0022] (3) The present invention significantly shortens the test cycle, reduces costs, and accelerates product development by optimizing the experimental process and data processing methods. The quantification method based on physical parameters reduces the subjectivity of human judgment, ensures the consistency and reliability of experimental results, and overcomes the problems of time-consuming, high-cost and subjective judgment in the prior art.

[0023] (4) The present invention not only focuses on the performance results of the seal at high temperature, but also builds the relationship between materials, structural parameters, compression force, and high-temperature sealing performance by real-time monitoring of the compression force changes, thereby evaluating the degree of attenuation of high-temperature sealing performance and the quality of high-temperature sealing performance of seals with different structures. The high-temperature degradation process and failure mode of the seal are revealed, providing a more in-depth analysis of the degradation mechanism, which is helpful for iterative optimization of the design and overcomes the deficiency of the lack of degradation mechanism analysis in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a method for evaluating the degree of attenuation of high-temperature sealing performance of a seal of the present invention; Figure 2 A schematic diagram of an experimental device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation of an Ω-shaped seal in an embodiment of the present invention; Figure 4 is a curve of compression force and back-fire side temperature in an embodiment of the present invention; Figure 5 is a curve of compression force and combustion time in an embodiment of the present invention; Among them, 1 is an upper pressure head, 2 is a seal, 3 is a thermocouple, 4 is a baffle, 5 is a force sensor, 6 is a flamethrower, and 7 is a lower fixture. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical methods in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work results are within the scope of protection of the present invention.

[0026] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0027] Example like Figure 2 and Figure 3 As shown, a silicone rubber seal for aviation is selected. First, the Ω-shaped aviation silicone rubber seal to be tested is cut into a sample with a length of 100 mm, and the seal is installed on a compression testing machine, which includes an upper pressure head 1, a lower clamp 7, a force sensor 5, a flamethrower 6, a baffle 4 and a thermocouple 3; the upper pressure 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, and the seal 2 is compressed by the downward pressure of the upper pressure head 1. The force sensor 5 is arranged below the test seal 2 to measure the compression force, and the flamethrower 6 is used to burn the test seal 2. The baffle 4 is arranged on the side of the test seal 2 away from the flamethrower 6, and the thermocouple 3 is arranged on the surface of the test seal 2 away from the flamethrower 6 to measure the back-fire side temperature. The pressure head is flat-plate shaped. The compression amount of the pressure 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 back-fire side of the seal to detect the temperature. The sealing cavity is evacuated to the service pressure.

[0028] like Figure 1 As shown in the figure, according to the test process, the samples are placed in the combustion test device simulating the actual working conditions, simulating the combustion of the aircraft in the high temperature fire environment. The butane flame spray gun is ignited, and the position 50mm in front of the seal tooling is kept still. The in-situ high temperature combustion test is carried out for 15 minutes, and the changing compression force and back-fire side temperature during the combustion process are recorded. The results are shown in Figure 4 shown.

[0029] Fit the relationship between the compression force and the backfire side temperature in the in-situ experiment, and establish the correlation model between the high-temperature sealing performance and compression force of the rubber seal during the entire combustion process through the compression force data corresponding to the backfire side temperature under actual service conditions. According to the experimental data, linear functions, exponential functions, polynomial functions, 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. The polynomial function model is selected as the relationship model between the compression force and the backfire side temperature, that is, where, , y is the compression force F, x is the back-fire side temperature T, constant a is a positive number, and b is a negative number. Parameter a represents the initial compression force F0 of the seal at the beginning of combustion; parameter b is a negative number, reflecting the trend that the compression force of the seal gradually decays with the increase of the back-fire side temperature; 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 mechanical properties of the seal can be quantified.

[0030] In the high-temperature in-situ experiment, the compression force changes continuously with time, and the compression force is related to the material and structural properties of the seal, such as Figure 5 As shown, the quantitative model of the compression force, material and structure of the seal proposed in this embodiment is: ; Among them, F is the compression force of the in-situ test in the experiment, 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 related to the flame coefficient, which is related to the shape of the flame during combustion and the temperature of the flame nozzle, and k is the shape coefficient, which is related to the design shape of the fireproof seal.

[0031] At this point, using the compression force of the seal as a bridge, the relationship between material structure parameters-compression force-high temperature sealing performance is established, so that the attenuation degree of the high temperature sealing performance of the seal and the quality of the high temperature sealing performance of seals with different structures can be quantitatively evaluated.

[0032] The specific implementation methods of the invention are described in detail above, but as examples, the present invention is not limited to the specific implementation methods described above. For those skilled in the art, any equivalent modification or substitution of the invention is also within the scope of the present invention. Therefore, the equivalent transformation, modification, improvement, etc. made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A device for evaluating the degree of attenuation of high-temperature sealing performance of a seal, characterized in that: Includes upper pressure head, lower fixture, force sensor, flamethrower, baffle and thermocouple; The upper pressure head and the lower clamp are respectively arranged on the upper side and the lower side of the seal to be tested, and 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, pressing the upper pressure head downward by a compression amount d, and inflating the sealed cavity isolated after the seal is compressed until the actual service pressure is reached; Step S2, using a flamethrower to burn the seal sample, and recording the compression force and 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, and establishing a functional relationship between the compression force of the seal and the back-fire side temperature; Step S4, quantitative evaluation of the attenuation of the sealing performance of the seal, based on the compression force of the samples with different combustion degrees, establish a correlation model between the seal structure-compression force-high temperature sealing performance during the entire combustion process, and quantitatively evaluate the attenuation degree 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 value 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 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 are 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 that the compression force of the seal gradually decays with the increase of combustion time; parameter c represents the change of 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 in the experiment, 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 seal shape coefficient.

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