Aviation sealant external field life evaluation method based on marine environment acceleration test

Abstract

The invention provides an aviation sealant external field life evaluation method based on a marine environment acceleration test, and relates to the field of acceleration tests and aviation sealant life evaluation, and the method comprises the steps: obtaining a marine environment test acceleration rate; the movable static sealing structure is used for carrying out external field marine environment acceleration tests under different acceleration test periods on the aviation sealant in the stress state; the movable static sealing structure after the acceleration test is combined with a detection bottom box to form a sealing performance detection box; connecting the sealing performance detection box into a pressure leakage detection system, and obtaining the sealing leakage rate of the aviation sealant in different acceleration test periods; determining a corresponding marine environment acceleration test period when the sealing leakage rate reaches a leakage threshold value; according to the determined marine environment acceleration test period and the obtained marine environment test acceleration multiplying power, the effective life of the aviation sealant in the external field marine environment is evaluated and obtained. The method can effectively predict the effective life of the aviation sealant in an external marine environment.

Description

Technical Field

[0001] This invention relates to the field of accelerated testing and sealing performance testing technology, specifically to a method for evaluating the field life of aviation sealants based on accelerated testing in a marine environment. Background Technology

[0002] In modern aviation industry, long service life and high reliability of airframe structures are core design objectives. Sealant, as a key functional material in aircraft structures, is widely used in critical areas such as mating surfaces, frames, window frames, and fairings of components like fuselages, wings, and tail fins. Its main function is to prevent the intrusion of moisture and corrosive media (such as salt spray), maintain structural integrity, and participate in load transfer and vibration damping to some extent. Especially for aircraft operating in marine environments (such as coastal patrol aircraft, carrier-based aircraft, and commercial airliners flying between islands), structural sealants face challenges far more severe than in inland environments. The high salinity and high humidity of the marine atmosphere significantly accelerate the aging, degradation, and failure of sealants. Sealant failure not only leads to structural corrosion (such as bulkhead corrosion and delamination) but can also damage aerodynamic shape, affect flight safety, and result in high maintenance costs.

[0003] Therefore, there is an urgent need in this field to develop a new method for assessing the field life of aviation sealants based on accelerated testing in a marine environment, in order to overcome the shortcomings of existing technologies. This method is of vital importance for developing scientific maintenance plans, ensuring flight safety, and controlling the total life cycle cost. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the present invention aims to provide a method for assessing the field lifespan of aviation sealants based on accelerated marine environmental testing. This method involves moving a static sealing structure to bring the aviation sealant into the required stress state, followed by accelerated testing in a marine environment. The sealant is then combined with a testing base box to form a sealing performance testing box, which is connected to a pressure leakage detection system to detect the sealing leakage rate of the aviation sealant under different accelerated testing cycles. By considering the accelerated testing cycle and the accelerated ratio of the marine environment test, the effective lifespan of the aviation sealant in the marine environment is assessed. This invention effectively covers the combined effects of stress and environmental factors, enabling the prediction of the effective lifespan of aviation sealants in a marine environment.

[0005] Specifically, on the one hand, the present invention provides a method for evaluating the field life of aviation sealants based on accelerated testing in a marine environment, which includes the following steps: S1. Obtain the acceleration rate for marine environmental testing; S2. Accelerated field marine environment tests were conducted on aviation sealants under stress conditions using a mobile static sealing structure under different accelerated test cycles. S3. Combine the accelerated test-tested moving static sealing structure with the test base box to form a sealing performance test box; S4. Connect the sealing performance test box to the pressure leakage detection system to obtain the sealing leakage rate of the aviation sealant under different accelerated test cycles. : ; in, The initial pressure inside the test chamber was used to test the sealing performance. To terminate the test, the pressure inside the sealing performance test chamber was measured. The initial temperature inside the test chamber was used to test the sealing performance. The temperature inside the sealing performance test box at the end of the test is V, the internal volume of the sealing performance test box is M, the molar mass of the gas is R, the gas constant is t, and the test time is t. S5. Determine the marine environment accelerated test cycle corresponding to when the sealing leakage rate reaches the leakage threshold. S6. Based on the determined marine environment accelerated test cycle and the obtained marine environment test acceleration ratio, evaluate the effective life of the aviation sealant in the field marine environment.

[0006] Preferably, S1, obtaining the acceleration rate for marine environmental testing, specifically includes: S11. Based on the marine environment of the field where the aviation sealant is located, construct a laboratory cyclic combination accelerated test profile; S12. Conduct field measurements and laboratory cyclic combination accelerated test profile verification of the sealant structural components under stress to obtain the acceleration ratio of marine environmental testing.

[0007] Preferably, the laboratory cyclic combined accelerated test profile includes a first stage of acidic salt spray test for 48 hours, a second stage of high temperature test for 7 days, and a third stage of alternating damp heat test for 5 days.

[0008] Preferably, the conditions for the acidic salt spray test include: chamber temperature 35±2℃, salt solution mass percentage 5±1%, pH adjusted to 3.0~4.0 with dilute sulfuric acid, and salt spray deposition rate 1.0~3.0 ml / 80cm. 2The test duration is 48 hours, consisting of 24 hours of spraying followed by 24 hours of drying. The high-temperature test conditions include: a temperature change rate of less than or equal to 3℃ / min, a chamber temperature of 70℃, and a test duration of 7 days. The alternating damp heat test includes 5 cycles, each lasting 24 hours. The test sequence and conditions for each cycle are as follows: a 2-hour heating phase, with the temperature rising from 30℃ to 60℃ and humidity at 95%RH; a 6-hour high-temperature and high-humidity phase, with a temperature of 60℃ and humidity at 95%RH; an 8-hour cooling phase, with the temperature decreasing from 60℃ to 30℃ and humidity at ≥85%RH; and an 8-hour low-temperature and high-humidity phase, with a temperature of 30℃ and humidity at 95%RH.

[0009] Preferably, when the tested aviation sealant is a sealing ring, the movable static sealing structure includes an upper pressure plate, a lower cover plate, and a height limiting ring. A first through hole is provided in the central area of ​​the lower cover plate, and the height limiting ring is disposed between the upper pressure plate and the lower cover plate, and the height limiting ring surrounds the first through hole.

[0010] Preferably, the detection box is a box with an internal cavity. A second through hole is opened in the central area of ​​the top wall of the detection box. An annular groove is provided around the second through hole. An annular ring is provided in the annular groove for sealing the lower cover plate of the moving static sealing structure during the test. An air inlet connected to the high pressure shut-off valve and an air outlet connected to the pressure and temperature transmitter are respectively provided on the side wall of the detection box.

[0011] Preferably, the pressure leakage detection system includes a high-pressure shut-off valve, a sealing performance testing box, and a pressure and temperature transmitter. The first end of the high-pressure shut-off valve is provided with a compressed air interface, and the second end of the high-pressure shut-off valve is airtightly connected to the sealing performance testing box and the pressure and temperature transmitter in sequence. The pressure and temperature transmitter is used to collect pressure and temperature data in the sealing performance testing box and transmit them to the host computer through a data acquisition card.

[0012] Preferably, S2, accelerating marine environmental tests under different accelerated test cycles are conducted on the aerospace sealant under stress using a movable static sealing structure, specifically including: S21. Obtain the compressibility of the aviation sealant under working conditions in a marine environment. S22. Set the height of the height-limiting ring according to the compression ratio; S23. The aviation sealant is placed between the upper pressure plate and the lower cover plate of the movable static sealing structure; when the detected aviation sealant is a sealing ring, the aviation sealant is placed around the first through hole. S24. The upper pressure plate is fixedly connected to the lower cover plate through the connecting structure, thereby pressing and restricting the aviation sealant and the height-limiting ring after the height setting together between the upper pressure plate and the lower cover plate. S25. Place the mobile static sealing structure carrying the stressed aviation sealant in the outdoor marine environment accelerated test environment and carry out accelerated tests with different accelerated test cycles.

[0013] Preferably, S4, the sealing performance test box is connected to the pressure leakage detection system to obtain the sealing leakage rate of the aviation sealant under different accelerated test cycles, including: S41. Connect the sealing performance test box under different accelerated test cycles to the pressure leakage detection system; S42. Connect the pressure leak detection system to the compressed air source and install a pressure gauge at the compressed air interface; S43. Open the high-pressure shut-off valve and input compressed air into the sealing performance test box through the air inlet on the side wall of the test box until the pressure gauge shows that the pressure has reached the required pressure. Then close the high-pressure shut-off valve and disconnect the compressed air source and pressure gauge. S44. Obtain the pressure data inside the sealing performance test box through the pressure and temperature transmitter, and transmit it to the host computer through the data acquisition card. S45. Set the acquisition frequency and time of the host computer to continuously record the pressure and temperature data inside the sealing performance test box; S46. Calculate the sealing leakage rate of the aviation sealant under different accelerated test cycles by combining the recorded pressure and temperature data with the volume of the sealing performance test chamber. ; ; in, The initial pressure inside the test chamber was used to test the sealing performance. To terminate the test, the pressure inside the sealing performance test chamber was measured. The initial temperature inside the test chamber was used to test the sealing performance. The temperature inside the sealing performance test chamber at the end of the test is V, the internal volume of the sealing performance test chamber is M, the molar mass of the gas is R, the gas constant is t, and the test time is t.

[0014] Preferably, before S3, the method further includes a step of fastening the test box to the non-porous cover plate, connecting it to the pressure leakage detection system, and testing the sealing performance of the test box structure itself and the pressure leakage detection system.

[0015] On the other hand, the present invention also provides an aviation sealant pressure leakage detection system based on accelerated testing in a marine environment. The system includes a high-pressure shut-off valve, a pressure and temperature transmitter, a data acquisition card, and a host computer. One end of the high-pressure shut-off valve is provided with a compressed air interface, and the other end of the high-pressure shut-off valve is airtightly connected to a sealing performance test box and a pressure and temperature transmitter. The pressure and temperature transmitter is used to collect pressure and temperature data in the sealing performance test box and transmit them to the host computer through the data acquisition card.

[0016] Preferably, the detection box is a box with an internal cavity. A second through hole is opened in the central area of ​​the top wall of the detection box. An annular groove is provided around the second through hole. An annular sealing ring is provided in the annular groove for sealing the lower cover plate of the moving static sealing structure during the test. An air inlet connected to the high pressure shut-off valve and an air outlet connected to the pressure and temperature transmitter are respectively provided on the side wall of the detection box.

[0017] Preferably, the present invention also provides a movable static sealing structure.

[0018] When the tested aviation sealant is a sealing ring, the movable static sealing structure includes an upper pressure plate, a lower cover plate, and a height limiting ring. A first through hole is opened in the central area of ​​the lower cover plate, and the height limiting ring is set between the upper pressure plate and the lower cover plate, and the height limiting ring surrounds the first through hole.

[0019] When the tested aviation sealant is a sealing cap or a sealing plug, the movable static sealing structure includes a lower cover plate and a limiting ring. The lower cover plate has a through hole in the central area, and the periphery of the through hole extends downward and is fixedly connected to the limiting ring to form an integral structure.

[0020] Preferably, the movable static sealing structure and the test base box are combined to form a sealing performance test box. The combination method can be to fasten the test base box and the lower cover plate of the movable static sealing structure with threaded fasteners to form an airtight connection.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Based on the environmental characteristics of high salt spray, high humidity and heat, and acidic media in the ocean, this invention designs a laboratory cyclic combination accelerated test profile of "acidic salt spray test + high temperature test + humidity and heat test", which truly simulates the coupling effect of multiple environmental factors in the ocean. The aging and damage effect of aviation sealant is evaluated through laboratory cyclic combination test, and the laboratory accelerated test ratio is obtained. The evaluation cycle is greatly shortened, which effectively improves the efficiency of research and development and maintenance. 2. This invention addresses the technical problem that aviation sealants are subject to compressive forces and complex environmental conditions during use, resulting in complex failure mechanisms. Traditional sealant evaluation methods cannot simultaneously cover the combined effects of stress and environmental factors. The invention innovatively proposes a mobile static sealing structure carrying the stressed aviation sealant, which is placed in an accelerated marine environment for testing. After the test, it is directly combined with a test box to form a sealing performance test box for testing the performance of the aviation sealant. This effectively covers the combined effects of stress and environmental factors, making the evaluation results more accurate and highly correlated with actual field conditions. 3. This invention uses a pressure leakage detection system to continuously record pressure and temperature data within the sealing performance testing chamber; and, combined with the volume of the sealing performance testing chamber, calculates the sealing leakage rate of the aviation sealant under different accelerated testing cycles. By determining the marine environment accelerated testing cycle corresponding to when the sealing leakage rate reaches the leakage threshold, and based on the laboratory accelerated testing ratio, the effective lifespan of aviation sealants in the marine environment is evaluated. A quantifiable accelerated testing-field lifespan conversion model is established, enabling airlines to upgrade their maintenance plans from a rough "periodic replacement" model to a precise "condition-based maintenance" or "condition-based maintenance" (CBM) model. This avoids waste caused by premature replacement and prevents safety risks caused by delayed replacement, achieving the best balance between cost and safety. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method for assessing the field lifespan of aviation sealants based on accelerated marine environmental testing according to the present invention. Figure 2 A schematic cross-sectional view of a laboratory cyclic combination accelerated test constructed according to one embodiment of the present invention; Figure 3 This is a schematic diagram of an alternating damp heat cycle according to one embodiment of the present invention; Figure 4 This is a schematic diagram of a movable static sealing structure according to one embodiment of the present invention; Figure 5 This is a partial component disassembly diagram of a movable static sealing structure according to one embodiment of the present invention; Figure 6 This is a schematic diagram of the sealing performance testing box according to one embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a pressure leak detection system according to one embodiment of the present invention; Figure 8 This is a temperature change trend diagram inside the sealing performance testing box according to an embodiment of the present invention; Figure 9 This is a graph showing the pressure change trend inside the sealing performance testing box according to an embodiment of the present invention. Detailed Implementation

[0023] The following is with reference to the appendix. Figure 1-9 The embodiments of the present invention will be described.

[0024] In a specific embodiment of the present invention, the present invention specifically provides a method for evaluating the field life of three types of aviation sealants based on accelerated marine environmental testing. The three types of aviation sealants include ring-shaped aviation sealants, cap-shaped aviation sealants, and columnar aviation sealants, specifically: The first type is a ring-shaped aviation sealant (such as a sealing ring): When used in the aviation field for aircraft hatches, the ring-shaped sealant is placed between the aircraft hatch and the aircraft hatch frame to play a sealing role. When the aircraft hatch is closed, the sealant is subjected to pressure; when the aircraft hatch is open, the sealant is not subjected to pressure, such as MS28778 elastomer O-ring.

[0025] The second type is cap-shaped aviation sealant (e.g., sealing cap): In the aviation field, it can be used for maintenance and observation caps of electronic equipment and sensors on aircraft, such as BACR15FS quick-release cap.

[0026] The third type is columnar aviation sealant (such as sealing plugs): In the aviation field, it can be used during aircraft assembly or maintenance to seal unused interfaces or test ports in hydraulic lines and fuel lines, such as BACB10AJ non-metallic solid plugs.

[0027] Example 1: To address the existing technical problems, when the tested aviation sealant is a ring-shaped aviation sealant, as shown in the attached... Figure 1 As shown, this invention provides a method for evaluating the field life of aviation sealants based on accelerated marine environmental testing, which includes the following steps: S1. Obtain the acceleration factor for marine environmental testing, specifically including: S11. Based on the marine environment of the field where the aviation sealant is located, construct a laboratory cyclic combination accelerated test profile; For the marine environment in which aviation sealants are used, taking the Wanning field as an example, Wanning has the characteristics of a marine environment with high salt spray, high humidity and heat, and acidic media. Considering the accelerated reaction of the sealant structure, this invention constructs a laboratory cyclic combination accelerated test profile of "acidic salt spray test + high temperature test + humidity and heat test", such as... Figure 2 As shown.

[0028] In each cycle of combined laboratory tests, preliminary tests were conducted to determine the following conditions: salt spray and damp heat test conditions were carried out in accordance with GJB150A, with the acidic salt spray test lasting for 2 days (24h spray + 24h drying); the high temperature test was set at 70 degrees Celsius, considering the maximum operating temperature of the sealant sample, and lasted for 7 days; the alternating damp heat test lasted for 5 days.

[0029] The specific conditions for the laboratory-simulated accelerated test are as follows.

[0030] Phase 1: Acidic Salt Spray Test Conditions: a) Test chamber temperature: 35±2℃; b) Salt solution: NaCl solution, with a mass percentage of 5±1%; c) pH value of the salt solution: Adjust the pH value to 3.0~4.0 by adding dilute sulfuric acid; d) Salt spray deposition rate: 1.0–3.0 ml / 80cm 2 ·h; e) Test duration: 24 hours of spraying followed by 24 hours of drying constitutes one cycle. The salt spray test duration in each cycle combination test is 2 days (24 hours of spraying + 24 hours of drying).

[0031] Phase Two: High Temperature Test Conditions a) Temperature change rate of the test chamber: not exceeding 3℃ / min; b) Chamber temperature: 70℃; c) Humidity control: Humidity will not be controlled during the experiment; d) Duration of the experiment: 24h*7, i.e., 7 days.

[0032] Phase Three: Alternating Damp Heat Test Conditions: a) Temperature range: 30℃~60℃; b) Humidity: 95%RH; c) Cyclic test conditions: see Table 1 below, and see schematic diagram below. Figure 3 ; d) Duration of the trial: 5 days.

[0033] Table 1: Alternating damp heat cycle test conditions (one cycle) S12. Conduct field measurements and laboratory cyclic combined accelerated test profile verification of the sealant structural components under stress conditions to obtain the acceleration ratio for marine environmental testing, including: S121. Select sealant structural components for comparative verification using different test methods; The samples used in this experiment were all from the same batch of sealant structural components to ensure a high degree of consistency in raw materials, manufacturing processes, and performance. To compare and verify different testing methods, this batch of samples was randomly divided into two groups: The first group of sealant structural components was used for field testing under stress conditions, and the seal leakage rate was tested. As an embodiment of the present invention, the sealant structural components under stress conditions underwent a three-year exposure test at the Wanning shed test station, and test data were collected periodically.

[0034] The second set of sealant structural components is used to conduct laboratory cyclic combined accelerated test profile verification test under the same stress conditions, and a seal leakage rate test is performed after each test cycle.

[0035] S122. Obtain different test times for two channels with the same sealing leakage rate; Obtain the seal leakage rate test results of two sets of sealant structural components, and find the different test times for the two methods under the same seal leakage rate.

[0036] S123. Calculate the acceleration rate of marine environmental testing using different test times in two channels; Acceleration rate for marine environmental testing = Test time of the first group of sealant structural components / Test time of the second group of sealant structural components.

[0037] As an example, this invention conducted field tests on a portion of the sealant structural components under the same stress state, and performed a laboratory cyclic combination accelerated test profile verification on another portion. The test verified that each cycle of the laboratory cyclic combination accelerated test can represent the aging damage effect of the sealant on the Wanning field exposure for 1 year, that is, the laboratory accelerated test ratio is 26.07 times.

[0038] S2. Accelerated field marine environment tests were conducted on aviation sealants under stress conditions using a mobile static sealing structure under different accelerated test cycles. To implement the method of the present invention, the present invention also provides a movable static sealing structure.

[0039] like Figure 4 , Figure 5 As shown, when the tested aviation sealant is a sealing ring, the movable static sealing structure includes an upper pressure plate, a lower cover plate, and a height limiting ring. A first through hole is opened in the central area of ​​the lower cover plate, and the height limiting ring is set between the upper pressure plate and the lower cover plate, and the height limiting ring surrounds the first through hole.

[0040] S21. Obtain the compressibility of the aviation sealant under working conditions in a marine environment. The compressibility of a sealing structure under operating conditions is one of the key parameters determining its sealing performance and lifespan. Simply put, it describes how much the seal is "flattened" after installation. This degree of "flattening" must be precisely controlled within a reasonable range; too little will cause leakage, and too much will damage it.

[0041] Compression ratio is a percentage used to measure the degree of compression deformation of a sealing ring after installation. Its calculation formula is: Compression ratio (%) = [(Original cross-sectional height of the seal ring d - Groove clearance height H after installation) / Original cross-sectional height of the seal ring] × 100%; In other words, the compression of the sealed structure is d - H, and the compression ratio is (d - H) / d × 100%.

[0042] Obtain the compression ratio of the aviation sealant under working conditions in a marine environment, which is equivalent to obtaining the groove clearance height H after the aviation sealant is installed.

[0043] S22. Set the height of the height-limiting ring according to the compression ratio; The height of the height-limiting ring is set according to the compression ratio. In other words, the height of the height-limiting ring limits the gap height between the two mating surfaces (i.e., between the upper pressure plate and the lower cover plate) after being subjected to force to H, so as to simulate the working state of aviation sealant under stress.

[0044] S23. An aviation sealant is placed between the upper pressure plate and the lower cover plate of the movable static sealing structure, and the aviation sealant is arranged around the first through hole; S24. The upper pressure plate is fixedly connected to the lower cover plate through the connecting structure, thereby pressing and restricting the aviation sealant and the height-limiting ring after the height setting together between the upper pressure plate and the lower cover plate. The upper pressure plate is pressed and fixedly connected to the lower cover plate via a connecting structure. Aviation sealant and height-limiting rings (with height settings) are then pressed and confined between the upper pressure plate and the lower cover plate. The connecting structure can be secured using a nut and bolt assembly. One height-limiting ring is fitted onto each bolt.

[0045] S25. Place the mobile static sealing structure carrying the stressed aviation sealant in the outdoor marine environment accelerated test environment and carry out accelerated tests with different accelerated test cycles.

[0046] A mobile static sealing structure carrying aerospace sealant under stress was placed in an accelerated marine environment for laboratory cyclic combined accelerated test profile verification under different accelerated test cycles.

[0047] Furthermore, prior to S3, the process includes steps such as securing the test box to the non-porous cover plate, connecting it to the pressure leak detection system, and testing the sealing performance of both the test box structure itself and the pressure leak detection system. This includes: After securing the test box to the non-perforated cover plate, connect it to the pressure leakage detection system. Connect the pressure leakage detection system to the compressed air source and install a pressure gauge at the compressed air interface. Open the high-pressure shut-off valve and input compressed air into the test box (after connecting the non-perforated cover plate) through the air inlet on the side wall of the test box until the pressure gauge shows the required pressure. Then, close the high-pressure shut-off valve and disconnect the compressed air source and pressure gauge. Connect the sealing performance testing device to the host computer, open the host computer software, and set the acquisition frequency and time according to the requirements (recommended 1 min / time, 24 h). Continuously record the pressure and temperature changes inside the test box. After reaching the pre-set measurement time, perform data analysis to determine the sealing performance of the test box. If the sealing performance does not meet the requirements, adjust the airtightness of each component of the pressure leakage detection system and the test box, and repeat the above test steps until the sealing performance is normal and good. Then proceed to step S3.

[0048] S3. Combine the accelerated test-tested moving static sealing structure with the test base box to form a sealing performance test box; To implement the method of the present invention, the present invention also provides a detection base box, which is a box body with an internal cavity. A second through hole is opened in the central area of ​​the top wall of the detection base box, and an annular groove is provided around the second through hole. An annular sealing ring is provided in the annular groove for sealing the lower cover plate of the moving static sealing structure during the test. An air inlet connected to a high-pressure shut-off valve and an air outlet connected to a pressure and temperature transmitter are respectively provided on the side wall of the detection base box.

[0049] The accelerated-tested mobile static sealing structure is combined with the test base box to form a sealing performance test box. The combination can be achieved by using threaded fasteners to secure the test base box to the lower cover plate of the mobile static sealing structure, ensuring an airtight seal. For example... Figure 6 As shown, one method involves drilling threaded holes at the four corners of the test box. These threaded holes are not connected to the internal cavity of the test box. Threaded holes are also provided at corresponding positions on the lower cover plate of the movable static sealing structure. During the fastening process, four screws are screwed into the threaded holes of the lower cover plate and then into the threaded holes at the four corners of the test box for tightening. During the tightening process, the annular sealing ring in the annular groove on the top wall of the test box is in a compressed and sealed state, thereby achieving a tight and airtight connection between the test box and the lower cover plate of the movable static sealing structure through threaded fasteners.

[0050] S4. Connect the sealing performance test box to the pressure leakage detection system to obtain the sealing leakage rate of the aviation sealant under different accelerated test cycles. : To implement the method of the present invention, such as Figure 7 As shown, the present invention also provides a pressure leakage detection system, which includes a high-pressure shut-off valve, a pressure and temperature transmitter, a data acquisition card and a host computer. The first end of the high-pressure shut-off valve is provided with a compressed air interface, and the second end of the high-pressure shut-off valve is connected in an airtight manner to a sealing performance test box and a pressure and temperature transmitter. The pressure and temperature transmitter is used to collect pressure and temperature data in the sealing performance test box and transmit them to the host computer through the data acquisition card.

[0051] Furthermore, a multi-channel data acquisition card and multiple sealing performance testing devices can be integrated and installed on the same device to form a multi-channel sealing performance testing device that can simultaneously test the sealing performance of multiple sealing structure samples (which can be parallel or non-parallel samples).

[0052] This invention connects a sealing performance testing box to a pressure leakage detection system to obtain the sealing leakage rate of aviation sealants under different accelerated testing cycles, including: S41. Connect the sealing performance test box under different accelerated test cycles to the pressure leakage detection system; S42. Connect the pressure leak detection system to the compressed air source and install a pressure gauge at the compressed air interface; S43. Open the high-pressure shut-off valve and input compressed air into the sealing performance test box through the air inlet on the side wall of the test box until the pressure gauge shows that the pressure has reached the required pressure. Then close the high-pressure shut-off valve and disconnect the compressed air source and pressure gauge. The compressed air source and high-pressure shut-off valve work together to control the air pressure input into the sealing performance test box. This air pressure can be adjusted as needed. Two openings on the side wall of the sealing performance test box are connected to the high-pressure shut-off valve and the pressure-temperature transmitter, respectively. The upper part of the test base box is connected to the moving static sealing structure being tested. The top opening of the test base box connects to the moving static sealing structure. A groove in the upper part of the test base box holds an annular ring, which is used for an airtight seal with the lower cover plate of the moving static sealing structure. Alternatively, an annular ring and sealing grease can be used for an airtight connection.

[0053] The method involves using an upper pressure plate and a height-limiting ring to press the tested ring-shaped aviation sealant onto the lower cover plate. The lower cover plate has a central opening, while the upper pressure plate does not. This ensures that the compressed air in the sealing performance test box can only leak at the leak point (if any) between the upper pressure plate, the ring-shaped aviation sealant, and the lower cover plate.

[0054] S44. Obtain the pressure data inside the sealing performance test box through the pressure and temperature transmitter, and transmit it to the host computer through the data acquisition card. S45. Set the acquisition frequency and time of the host computer to continuously record the pressure and temperature data inside the sealing performance test box; S46. Calculate the sealing leakage rate of the aviation sealant under different accelerated test cycles by combining the recorded pressure and temperature data with the volume of the sealing performance test chamber. ; ; in, The initial pressure inside the test chamber was used to test the sealing performance. To terminate the test, the pressure inside the sealing performance test chamber was measured. The initial temperature inside the test chamber was used to test the sealing performance. The temperature inside the sealing performance test chamber at the end of the test is V, the internal volume of the sealing performance test chamber is M, the molar mass of the gas is R, the gas constant is t, and the test time is t.

[0055] When the gas pressure inside the sealed test box is below 10 atmospheres at room temperature, the leakage of gas before and after the test in this detection method can be calculated based on the ideal gas law, as follows: Let the volume of the sealed test box (including the parts connected to the high-pressure shut-off valve, pressure and temperature transmitters, upper and lower cover plates, etc.) be V, the initial pressure inside the box be p0, the initial gas temperature be T0, the mass of compressed air be m0, the test time be t, and the pressure, gas temperature, and compressed air mass at the end of the test be p1, T1, and m1.

[0056] The ideal gas law is: Where P represents the gas pressure, V represents the gas volume, n represents the amount of substance of the gas, T represents the thermodynamic temperature of the gas, R is a constant called the ideal gas constant or molar gas constant, m is the gas mass, and M is the molar mass of the gas.

[0057] Under the initial test conditions, the equation of state for the compressed air inside the sealed box can be expressed as: ; At the end of the test, the equation of state for the compressed air inside the sealed box can be expressed as: ; The mass of a gas leak can be expressed as: ; The leakage rate, expressed as gas mass loss, is: ; in: --Average leakage rate expressed as gas mass loss, in g / h; --Initial pressure inside the box, in Pa; --Pressure inside the chamber at the end of the test, in Pa; --Initial temperature inside the box, in K; --Temperature inside the chamber at the end of the test, in K; V--Internal volume of the sealed test chamber, in K; V-- M -- gas molar mass, in g / mol; R -- gas constant, with a value of 8.31 J / (mol·K); t -- test time, in h.

[0058] S5. Determine the marine environment accelerated test cycle corresponding to when the sealing leakage rate reaches the leakage threshold. S6. Based on the determined marine environment accelerated test cycle and the obtained marine environment test acceleration ratio, evaluate the effective life of the aviation sealant in the field marine environment.

[0059] The following example uses the test results of a sample that has undergone three accelerated marine environmental testing cycles to calculate the average leakage rate of the sample within the calibration period. The recorded temperature change trend inside the sealing performance test chamber during the test is shown below. Figure 8 As shown, the pressure change trend Figure 9 As shown, the corresponding data (one set per hour) is shown in Table 2 below: Table 2 Record of Sealing Performance Test Results for a Certain Sample Taking a calibration time of 24 hours as an example, the values ​​of each parameter in the formula can be obtained from the table above: =3.38×10 5 Pa; =2.96×10 5 Pa; =22.62℃=295.77K; =22.49℃=295.64K; t=24h. Additionally, the molar mass of air is M=29g / mol; the gas constant is R=8.314 J / (mol·K); the calculated volume of the sealed detection box is approximately: V= The 24-hour leakage rate of a certain sample can be calculated as follows: =2.06× g / h.

[0060] Because of 2.06× g / h < Leakage threshold 4× The concentration of g / h indicates that the leakage threshold has not been reached and the leakage rate remains within the effective lifespan.

[0061] Using this method, if the leakage rate of the sample reaches the leakage threshold after n accelerated marine environmental testing cycles, then the corresponding accelerated marine environmental testing cycle is n. Based on the obtained accelerated marine environmental testing rate, the effective lifespan of the aviation sealant in the marine environment can be assessed as n-1 years.

[0062] By establishing a model of the relationship between leakage rate and time, it is possible to predict when the seal will reach its failure threshold. This allows users to shift from "repairing after it breaks" (passive maintenance) to "replacing before it breaks" (predictive maintenance), greatly reducing the risk and cost of unplanned downtime.

[0063] Example 2: To address the problems of existing technologies, when the tested aviation sealant is a sealing cap or a sealing plug, this invention provides a method for evaluating the field life of aviation sealants based on accelerated marine environmental testing, which includes the following steps: P1. Obtain the acceleration ratio for marine environmental testing; (This step is the same as S1 above) P2. Accelerated field marine environment tests were conducted on aviation sealants under stress conditions using a mobile static sealing structure under different accelerated test cycles. To achieve the method of the present invention, the present invention also provides a movable static sealing structure. When the detected aviation sealant is a sealing cap or a sealing plug, the movable static sealing structure includes a lower cover plate and a limiting ring. A through hole is provided in the central area of ​​the lower cover plate, and the periphery of the through hole extends downward and is fixedly connected to the limiting ring to form an integral structure.

[0064] For sealing caps, taking the BACR15FS quick-release cap as an example, it is a standard part from Boeing, specifically used to seal openings in aircraft piping systems. Its structure can be divided into three parts: Bottom disc: This is its sealing surface. An O-ring is usually installed at the bottom of this disc. When the plug is installed in place, the O-ring is compressed to achieve a seal on the pipe end face.

[0065] Sealing lip (guide ring): On the BACR15FS, the sealing lip is a flexible claw ring. It consists of several elastic flaps with barbs. It performs two core functions: Positioning and Guiding: Similar to the sealing lip, this claw ring is inserted into the pipe hole during installation to ensure that the center of the plug is aligned with the center of the pipe. This ensures that the bottom O-ring is pressed flat and evenly onto the sealing surface, which is the first step in achieving a reliable seal.

[0066] Quick locking: When you forcefully push the plug into the pipeline, the elastic flap of the claw ring will retract inward, allowing it to pass smoothly through the pipeline hole.

[0067] Once the O-ring has fully extended out of the pipe, it will instantly spring back to its original position. The barbs on the O-ring will firmly "bite" the back of the pipe end face, producing a clear "click" sound, indicating that it has been locked in place. This locking force provides sufficient axial preload to press the bottom O-ring tightly against the sealing surface, thus completing the seal.

[0068] In this invention, a through hole is provided in the central area of ​​the lower cover plate, and the periphery of the through hole extends downward and is fixedly connected to the limiting ring to form an integral structure. That is to say, by setting the diameter of the limiting ring, the sealing lip of the sealing cover can be provided with the same axial preload as in the working state.

[0069] P21. Obtain the compression ratio of the sealing cap under working conditions in an outdoor marine environment. P22. Set the diameter of the limiting ring according to the compression ratio; The diameter of the upper limit ring of the lower cover plate can be set by using a one-piece molding manufacturing method.

[0070] P23. Insert the sealing lip of the sealing cap into the limiting ring so that the O-ring at the bottom of the sealing cap finally contacts the end face of the lower cover plate and is compressed, thus achieving a reliable end face seal. P24. Place the mobile static sealing structure carrying the stressed aviation sealant in the outdoor marine environment accelerated test environment and carry out accelerated tests with different accelerated test cycles.

[0071] P3. Combine the accelerated test-tested moving static sealing structure with the test base box to form a sealing performance test box; P4. Connect the sealing performance test box to the pressure leakage detection system to obtain the sealing leakage rate of the aviation sealant under different accelerated test cycles. : P5. Determine the marine environment accelerated test cycle corresponding to when the sealing leakage rate reaches the leakage threshold. P6. Based on the determined marine environment accelerated test cycle and the obtained marine environment test acceleration ratio, the effective life of the aviation sealant in the field marine environment is evaluated.

[0072] The implementation of the other steps above is similar to that in Example 1, and will not be repeated here.

[0073] For sealing plugs, taking the BACB10AJ non-metallic solid plug as an example, its structure is typically a solid, integral conical or cylindrical part, similar to a "bottle stopper." Sealing principle: radial interference and compression sealing. It generates strong radial pressure, tightly "hugging" the pipe wall, thus preventing any fluid from leaking along the pipe wall.

[0074] In its field life assessment of aerospace sealants based on accelerated marine environment testing, only in the step "P23, insert the sealing lip of the sealing cap into the limiting ring so that the O-ring at the bottom of the sealing cap finally contacts the end face of the lower cover plate and is compressed to achieve a reliable end face seal", the sealing plug is directly inserted into the limiting ring to form the required radial pressure and compression ratio. The implementation of other steps is similar to the steps in Example 2, and will not be repeated here.

[0075] For other types of samples (different compression ratios, different sizes, or other sealing materials with the same main components), the method described in this article can be used to conduct laboratory accelerated tests, test the sealing leakage rate of the samples under different test cycles, find the leakage rate threshold, determine the test cycle corresponding to the threshold, and calculate its effective life in a humid and hot marine atmospheric environment based on the acceleration ratio.

[0076] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An aviation sealant field life evaluation method based on marine environment accelerated test, characterized in that, It comprises steps of: S1, obtaining a marine environment test acceleration ratio; S2, using a mobile static sealing structure to carry out an external field marine environment accelerated test on the stressed state of the aviation sealant under different accelerated test periods; S3, combining the mobile static sealing structure after the accelerated test with a detection bottom box to form a sealing performance detection box; S4, connect the sealing performance detection box to the pressure leakage detection system to obtain the sealing leakage rate of the aviation sealant under different accelerated test periods : ； wherein, P0 is the initial pressure in the leak detection chamber, Pf is the final pressure in the leak detection chamber at the end of the test, T0 is the initial temperature in the leak detection chamber, Tf is the temperature in the leak detection chamber at the end of the test, V is the volume of the leak detection chamber, M is the molar mass of the gas, R is the gas constant, and t is the test time. S5, determining the marine environment accelerated test period corresponding to the sealing leakage rate reaching the leakage threshold; S6, evaluating the effective life of the aviation sealant in the external field marine environment according to the determined marine environment accelerated test period and the obtained marine environment test acceleration ratio.

2. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, characterized in that, S1, obtaining a marine environment test acceleration ratio, specifically comprising: S11, constructing a laboratory cyclic combined accelerated test profile according to the marine environment of the external field where the aviation sealant is located; S12, measuring the stressed state of the sealant structure in the field and verifying the laboratory cyclic combined accelerated test profile to obtain the marine environment test acceleration ratio.

3. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 2, characterized in that, The laboratory cyclic combined accelerated test profile comprises a first stage of acid salt spray test for 48 hours, a second stage of high temperature test for 7 days, and a third stage of alternating damp heat test for 5 days.

4. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, wherein The conditions of the acid salt spray test include: test box temperature 35±2℃, salt solution mass percentage content 5±1%, salt solution added with dilute sulfuric acid to adjust pH value 3.0~4.0, salt spray deposition rate 1.0~3.0 ml / 80cm 2 ·h, the test duration is 24h after spraying and 24h after drying, and the total time is 48h; the conditions of the high temperature test include: test box temperature change rate less than or equal to 3℃ / min, test box temperature 70℃, and test duration 7 days; the alternating damp heat test includes 5 cycles, and each cycle lasts for 24h; the test sequence and conditions of each cycle include: temperature rising stage lasting for 2h, temperature rising from 30℃ to 60℃, and humidity 95%RH; high temperature and high humidity stage lasting for 6h, temperature 60℃, and humidity 95%RH; temperature falling stage lasting for 8h, temperature falling from 60℃ to 30℃, and humidity≥85RH; low temperature and high humidity stage lasting for 8h, temperature 30℃, and humidity 95RH.

5. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, wherein When the detected aviation sealant is a sealing ring, the mobile static sealing structure comprises an upper pressing plate, a lower cover plate, and a height limiting ring, a first through hole is formed in the central region of the lower cover plate, and the height limiting ring is arranged between the upper pressing plate and the lower cover plate and surrounds the first through hole.

6. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, wherein The detection bottom box is a box body with an internal chamber, a second through hole is formed in the central region of the top wall of the detection bottom box, an annular groove is arranged around the second through hole, and a ring-shaped ring is arranged in the annular groove for air-tight sealing with the lower cover plate of the mobile static sealing structure during sealing detection; an air inlet connected with a high-pressure stop valve and an air outlet connected with a pressure and temperature transmitter are arranged on the side wall of the detection bottom box.

7. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, wherein The pressure leakage detection system comprises a high-pressure stop valve, a sealing performance detection box, and a pressure and temperature transmitter, the first end of the high-pressure stop valve is provided with a compressed air interface, the second end of the high-pressure stop valve is air-tightly connected with the sealing performance detection box and the pressure and temperature transmitter in sequence, and the pressure and temperature transmitter is used to collect pressure and temperature data in the sealing performance detection box and transmit the data to an upper computer through a data acquisition card.

8. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 5, wherein S2, using a mobile static sealing structure to carry out an external field marine environment accelerated test on the stressed state of the aviation sealant under different accelerated test periods, specifically comprising: S21, obtaining the compression rate of the aviation sealant in the external field marine environment working state; S22, setting the height of the height limiting ring according to the compression rate; S23, arranging the aviation sealant between the upper pressing plate and the lower cover plate of the mobile static sealing structure; when the detected aviation sealant is a sealing ring, the aviation sealant surrounds the first through hole; S24, fixedly connecting the upper pressing plate and the lower cover plate through a connecting structure, so as to press and limit the aviation sealant and the height set height limiting ring between the upper pressing plate and the lower cover plate; S25, placing the mobile static sealing structure carrying the stressed state aviation sealant in the external field marine environment accelerated test environment to carry out accelerated test of different accelerated test periods.

9. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, wherein S4, connect the sealing performance detection box to the pressure leakage detection system to obtain the sealing leakage rate of the aviation sealant under different accelerated test periods, including: S41, connect the sealing performance detection box under different accelerated test periods to the pressure leakage detection system; S42, connect the pressure leakage detection system to the compressed air source, and set a pressure gauge at the compressed air interface; S43, open the high-pressure stop valve, input compressed air into the sealing performance detection box through the air inlet on the side wall of the bottom box, and close the high-pressure stop valve and remove the compressed air source and the pressure gauge when the pressure gauge shows that the pressure reaches the required pressure; S44, obtain the pressure data in the sealing performance detection box through the pressure temperature transmitter, and transmit the data to the upper computer through the data acquisition card; S45, set the acquisition frequency and time of the upper computer, and continuously record the pressure and temperature data in the sealing performance detection box; S46, calculate the sealing leakage rate of the aviation sealant under different accelerated test periods by combining the recorded pressure and temperature data with the volume of the sealing performance detection box ; ； wherein, P0 is the initial pressure in the leak detection chamber, Pf is the pressure in the leak detection chamber at the end of the test, T0 is the initial temperature in the leak detection chamber, Tf is the temperature in the leak detection chamber at the end of the test, V is the volume of the leak detection chamber, M is the molar mass of the gas, R is the gas constant, and t is the test time.

10. The method for evaluating the field life of an aviation sealant based on a marine environment accelerated test according to claim 1, wherein Before S3, it also includes the steps of connecting the detection bottom box to the non-porous cover plate, connecting to the pressure leakage detection system, and testing the sealing performance of the detection bottom box structure itself and the pressure leakage detection system.

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