Accelerated aging test method for rubber seals simulating the service environment of aircraft engines

Abstract

This invention belongs to the technical field of aging life evaluation of rubber seals, and relates to an accelerated aging test method for rubber seals simulating the service environment of an engine. The invention consists of two test steps: accelerated aging in a simulated parking environment and accelerated aging in a simulated operating environment. Furthermore, the accelerated aging step in the simulated operating environment incorporates a cyclic test method with a sub-cycle of "high-temperature pressurization + cooling and depressurization." This method is used to study the aging patterns and life prediction of rubber seals in simulated aero-engine service environments. It comprehensively considers the environmental impact of rubber seals in both parking and operating states during their service life on aero-engines. The test method and related parameter values ​​can effectively simulate the aging process and mechanism of rubber seals in aero-engine service environments, allowing for more accurate acquisition of the aging patterns of rubber seals used in aero-engines, and serving as a fundamental test method for predicting their service life.

Description

Technical fields:

[0001] This invention belongs to the technical field of aging life evaluation of rubber seals, and relates to an accelerated aging test method for rubber seals that simulates the service environment of an engine. Background technology:

[0002] Rubber seals are widely used in aero engines to seal media such as lubricating oil, fuel, and air. Although the overall usage is not large, the types and applications are numerous, and their role is crucial. If rubber seals age and fail, oil and air leaks will inevitably occur. This can lead to component malfunctions and functional failures, affecting the overall equipment's availability, or even causing damage to the entire equipment, shutdown, and safety accidents. Currently, the aging and failure of rubber seals has become a key factor restricting the lifespan of related products, directly affecting the overall reliability and safety of aero engines. Therefore, it is essential to conduct research on the aging patterns and lifespan prediction of rubber seals used in aero engines.

[0003] Currently, research on the aging behavior of rubber seals mainly employs two types of testing methods: natural aging and accelerated aging. Natural aging tests are limited to studying the aging behavior of rubber seals under natural environmental conditions and cannot be used to study the aging behavior of rubber seals operating on aero-engines. Accelerated aging tests specifically include methods such as hot air aging, oxygen bomb aging, hot oil aging, artificial climate accelerated aging, damp heat aging, ozone aging, salt spray, and mold testing. On the one hand, some aging test methods (such as artificial climate accelerated aging) differ significantly from the service environment of rubber seals on aero-engines, and the aging patterns obtained are not highly correlated with the aging patterns of rubber seals during service on aero-engines. On the other hand, these accelerated aging test methods still use single-factor accelerated aging, often failing to reflect the combined aging effects of multiple factors encountered by rubber seals during service on aero-engines, such as ambient temperature, operating temperature, lubricating oil / fuel / air medium, medium pressure, and mechanical deformation. Summary of the Invention:

[0004] To address the aforementioned issues, considering that the service environment of aero-engines consists of two states: parking and operation, the rubber seals in the parking state are mainly affected by factors such as high temperature and compression deformation in the natural atmospheric environment, while in the operation state, the rubber seals are mainly affected by factors such as high temperature, medium, pressure, and compression deformation in the aero-engine operating conditions. Taking into account the environmental characteristics of the rubber seals during service, which involve alternating parking and operation phases and the combined effects of multiple environmental factors, the accelerated aging test method for rubber seals that simulates the engine service environment provided by this invention can effectively simulate and reproduce the comprehensive aging environmental effects of rubber seals during service on aero-engines, thereby improving the accuracy of aging law research and life prediction for rubber seals used in aero-engines.

[0005] To achieve the above objectives, the technical solution of the present invention is an accelerated aging test method for rubber seals that simulates the service environment of an aero-engine.

[0006] First, a simulation test device with a pressure relief valve is designed based on the assembly dimensions of the rubber sealing ring, component materials, surface treatment process, and medium pressure of the actual sealing structure. The rubber sealing ring is installed in the sealing ring groove of the simulation test device. The medium required for sealing the actual sealing structure is injected into the simulation test device, so that the medium is under natural atmospheric pressure. The simulation test device is placed in a high-temperature test chamber to prepare for the test.

[0007] Then, an accelerated aging test was conducted using a cyclical test method consisting of two test steps: accelerated aging under simulated parking conditions and accelerated aging under simulated working conditions.

[0008] Step 1: Simulate accelerated aging in the parking environment

[0009] Maintain the medium pressure in the simulation test apparatus at 0 MPa, and adjust the high-temperature test chamber to raise and maintain the ambient temperature of the simulation test apparatus at ambient temperature T. p The test was conducted for 120 to 720 hours under these ambient temperature and medium pressure conditions.

[0010] Step 2: Simulated accelerated aging under working conditions

[0011] Accelerated aging under simulated working conditions is a cyclic test consisting of two sub-steps.

[0012] 1) High-temperature pressure testing

[0013] Adjust the high-temperature test chamber to simulate the ambient temperature T of the test device. p Increase and maintain the accelerated aging temperature T w A medium pump is used to pressurize the medium in the simulation test device, maintaining the medium pressure at the typical pressure value P during the operation of an aero-engine. wAt accelerated aging temperature Tw and medium pressure P w The experiment was conducted for 1 to 6 hours under the specified conditions.

[0014] 2) Cooling and depressurization

[0015] Adjust the high-temperature test chamber to reduce the ambient temperature of the simulated test device from the accelerated aging temperature T. w The pressure was reduced to room temperature, and the pressure of the medium in the simulation test device was reduced from P through the pressure relief valve. w After the pressure drops to 0 MPa and the cooling and depressurization step 2) is completed, immediately repeat the high-temperature pressurization step 1), and continue this cycle until the accelerated aging of the simulated working environment reaches the preset number of "high-temperature pressurization + cooling and depressurization" cycles N. w Or P during high temperature and pressure w Until it can no longer be maintained within the normal operating range of the media system;

[0016] After the accelerated aging step 2 under simulated working conditions is completed, immediately repeat the accelerated aging step 1 under simulated parking conditions. Continue this cycle until the entire accelerated aging test reaches the preset total number of cycles N, or the high-temperature pressure test P. w The test ends when the system can no longer maintain its normal operating range.

[0017] Step 1, which simulates accelerated aging in a parking environment, is used to simulate the natural environmental aging effects accumulated on the rubber seals of an aircraft engine during its one-year service life while it is parked.

[0018] The accelerated aging temperature T in step 1 p Temperatures should be above ambient temperature and at least 20°C below the typical operating temperature of the medium.

[0019] Step 2, simulating accelerated aging under working conditions, is used to simulate the aging effect of the rubber seals accumulated under working conditions during the one-year service period of an aero-engine.

[0020] In step 1), the accelerated aging temperature T w The temperature should not be lower than the typical operating temperature of the medium, and should not be higher than the maximum temperature that the rubber sealing ring material can withstand during operation.

[0021] In step 1), the booster pump is matched with the specific medium type, such as air, fuel oil, or lubricating oil.

[0022] The typical pressure value P during the operation of the aero-engine in step 1) is mentioned above. w This refers to a specific pressure value within the normal operating range of a particular media system, such as an air system, fuel system, or lubricating oil system.

[0023] The number of cycles N for "high-temperature pressurization + cooling and depressurization" in step 2) is as follows. wThe range is set to 100 to 400 times, corresponding to the number of times an aero engine operates per year.

[0024] The total number of accelerated aging tests, N, is set to 3 to 15 times, corresponding to the number of calendar years when the aero-engine reaches its first overhaul period.

[0025] The actual assembly dimensions of the rubber sealing ring in the sealing structure include: the cross-sectional shape, depth, width, and sealing gap of the sealing ring groove.

[0026] The accelerated aging test method for rubber seals simulating the service environment of an aero-engine, as employed in this invention, consists of two test steps: accelerated aging in a simulated parking environment and accelerated aging in a simulated operating environment. Furthermore, the accelerated aging step in the simulated operating environment incorporates a cyclic test method with a sub-cycle of "high-temperature pressurization + cooling and depressurization." This method is used to study the aging patterns and lifespan prediction of rubber seals in simulated aero-engine service environments. It comprehensively considers the environmental impacts of rubber seals in both parking and operating states during their service life on aero-engines. In the parking state, the seals are mainly affected by high temperatures and compression deformation in the natural atmospheric environment. In the operating state, they are mainly affected by high temperatures, media, pressure, and compression deformation under aero-engine operating conditions. The test method and the values ​​of relevant condition parameters can effectively simulate the aging process and mechanism of rubber seals in the service environment of aero-engines, allowing for a more accurate acquisition of the aging patterns of rubber seals used in aero-engines, and serving as a fundamental test method for predicting their service life. Detailed implementation method:

[0027] The following examples further illustrate the specific implementation of the accelerated aging test method for rubber seals simulating engine service environments. It should be noted that these examples are only for further illustrative purposes and do not limit the scope of the invention. Various improvements made by those skilled in the art after reading this patent without departing from the essence of the invention are obvious and fall within the scope of protection claimed by this invention.

[0028] Accelerated aging test method for rubber seals simulating the service environment of aircraft engines.

[0029] First, a simulation test device with a pressure relief valve is designed based on the assembly dimensions of the rubber sealing ring, component materials, surface treatment process, and medium pressure of the actual sealing structure. The rubber sealing ring is installed in the sealing ring groove of the simulation test device. The medium required for sealing the actual sealing structure is injected into the simulation test device, so that the medium is under natural atmospheric pressure. The simulation test device is placed in a high-temperature test chamber to prepare for the test.

[0030] Then, an accelerated aging test was conducted using a cyclical test method consisting of two test steps: accelerated aging under simulated parking conditions and accelerated aging under simulated working conditions.

[0031] Step 1: Simulate accelerated aging in the parking environment

[0032] Maintain the medium pressure in the simulation test apparatus at 0 MPa, and adjust the high-temperature test chamber to raise and maintain the ambient temperature of the simulation test apparatus at ambient temperature T. p The test was conducted for 120 to 720 hours under these ambient temperature and medium pressure conditions.

[0033] Step 2: Simulated accelerated aging under working conditions

[0034] Accelerated aging under simulated working conditions is a cyclic test consisting of two sub-steps.

[0035] 1) High-temperature pressure testing

[0036] Adjust the high-temperature test chamber to simulate the ambient temperature T of the test device. p Increase and maintain the accelerated aging temperature T w A medium pump is used to pressurize the medium in the simulation test device, maintaining the medium pressure at the typical pressure value (0.3MPa~6.5MPa) during aero-engine operation. w At accelerated aging temperature Tw and medium pressure P w The experiment was conducted for 1 to 6 hours under the specified conditions.

[0037] The accelerated aging of the simulated parking environment is used to simulate the natural environmental aging effect accumulated by the rubber seals of an aircraft engine during its one-year service period while it is parked.

[0038] The accelerated aging temperature T p Temperatures should be at least 20°C above ambient temperature and at least 20°C below the typical operating temperature of the medium (100°C to 250°C).

[0039] The accelerated aging temperature T w The temperature should not be lower than the typical operating temperature of the medium (100℃~250℃) and should not exceed the maximum temperature that the rubber sealing ring material can withstand during operation.

[0040] The booster pump is matched with specific media types such as air, fuel oil, and lubricating oil.

[0041] The typical pressure value P during the operation of the aircraft engine w This refers to a specific pressure value within the normal operating range of a particular media system, such as an air system, fuel system, or lubricating oil system.

[0042] 2) Cooling and depressurization

[0043] Adjust the high-temperature test chamber to reduce the ambient temperature of the simulated test device from the accelerated aging temperature T. wThe pressure was reduced to room temperature, and the pressure of the medium in the simulation test device was reduced from P through the pressure relief valve. w After the pressure drops to 0 MPa and the cooling and depressurization step 2) is completed, immediately repeat the high-temperature pressurization step 1), and continue this cycle until the accelerated aging of the simulated working environment reaches the preset number of "high-temperature pressurization + cooling and depressurization" cycles N. w Or P during high temperature and pressure w Until it can no longer be maintained within the normal operating range of the medium system; the accelerated aging of the simulated working environment is used to simulate the aging effect of the working environment accumulated by the rubber seals under working conditions during one year of service of an aircraft engine.

[0044] The number of cycles Nw for "high temperature pressurization + cooling and depressurization" is set to 100 to 400 times, corresponding to the number of times the aero engine operates per year.

[0045] After the accelerated aging step 2 under simulated working conditions is completed, immediately repeat the accelerated aging step 1 under simulated parking conditions. Continue this cycle until the entire accelerated aging test reaches the preset total number of cycles N, or the high-temperature pressure test P. w The test ends when the system can no longer maintain its normal operating range.

[0046] The total number of accelerated aging tests, N, is set to 3 to 15 times, corresponding to the number of calendar years when the aero-engine reaches its first overhaul period. The actual assembly dimensions of the rubber sealing ring in the sealing structure include: the cross-sectional shape, depth, width, and sealing gap of the sealing ring groove.

[0047] Example:

[0048] FX-17 fluororubber sealing rings are used for sealing the fuel system pipelines of a certain aircraft engine. Their dimensions are: inner diameter Φ142.5mm, cross-sectional diameter Φ21.8mm. They are installed on pipelines with a diameter of Φ... a On a 46.34mm TC4 titanium alloy (untreated) pipe, the bottom diameter of the sealing ring groove is Φ g 43.5mm, shaft groove width is 2.6mm, the outer cylinder for sealing is also made of TC4 titanium alloy (untreated), and the fitting bore diameter is Φ. A 46.34mm, the sealing medium is Pegasus II lubricating oil, the typical operating temperature is 200℃, and the normal operating range of Pegasus II lubricating oil pressure in the fuel system pipeline during the operation of the aircraft engine is 0.3MPa~0.5MPa.

[0049] First, the simulated test device for accelerated aging testing was designed and fabricated. FX-17 fluororubber sealing rings were installed, and the device was filled with Pegasus II lubricating oil. Preferably, the main body of the simulated test device was made of TC4 titanium alloy, the same material used in the actual components. The main body of the device consists of a cylinder and a cover: the cylinder has an inner diameter of 150mm, an outer diameter of 158mm, a height of 50mm, and a wall thickness of 4mm; one end is closed, and the other is open, with a needle-type pressure relief valve installed at the closed end; the cover has a diameter of 158mm and a thickness of 6mm. Three openings with an outer diameter of 46.34mm, an inner diameter of 35mm, and a length of 10mm are welded onto the cover. A bottom diameter of Φ is machined onto each of the three openings. g A 43.5mm wide and 2.6mm wide shaft groove is used to seal the cylinder cover to the open end of the cylinder. FX-17 fluororubber sealing rings with an inner diameter of Φ142.5mm and a cross-sectional diameter of Φ21.8mm are installed on the shaft grooves of the three pipe ports. One pipe port is sealed with a 66mm outer diameter and 46.34mm inner diameter closed round cap (plug, made of TC4 titanium alloy), and the closed round cap is fixed to the cylinder cover via a flange connection. The other two pipe ports and inlet / outlet oil pipes and their valves are connected using a 66mm outer diameter and 46.34mm inner diameter through-hole round cap (made of TC4 titanium alloy), and these two through-hole round caps are also fixed to the cylinder cover via flange connections. With one end of the cylinder cap facing upwards, inject Pegasus II lubricating oil into the simulation test apparatus using an external oil pump, inlet pipe, and outlet pipe. Once the apparatus is full of Pegasus II lubricating oil, close both the inlet and outlet pipe valves to seal the Pegasus II lubricating oil within the simulation test apparatus. Invert the simulation test apparatus so that the sealed end of the cylinder and the needle-shaped pressure relief valve are vertically facing upwards. Manually open the needle-shaped pressure relief valve to bring the pressure of the Pegasus II lubricating oil to atmospheric pressure (i.e., unsealed, with the pressure gauge on the lubricating oil pipeline displaying 0 MPa). Place the simulation test apparatus in the STPH-102 high-temperature test chamber to prepare for the test.

[0050] Then, an accelerated aging test was conducted using a cyclical test method consisting of two test steps: accelerated aging under simulated parking conditions and accelerated aging under simulated working conditions.

[0051] Step 1): Simulate accelerated aging in a parking environment

[0052] Maintain the pressure of the Pegasus II lubricating oil in the simulation test device at 0 MPa, adjust the STPH-102 high temperature test chamber to raise the ambient temperature of the simulation test device and keep it at the accelerated aging temperature of 150℃ (far higher than the highest temperature of various natural environments and 50℃ lower than the typical working temperature), and test for 360 hours under the conditions of 0 MPa and 150℃.

[0053] Step 2): Accelerated aging under simulated working conditions

[0054] Accelerated aging under simulated working conditions is a cyclic test consisting of two sub-steps.

[0055] Sub-step 1): High-temperature pressure testing

[0056] Close the manually operated needle-type pressure relief valve to enable its automatic opening. Adjust the STPH-102 high-temperature test chamber to raise the ambient temperature of the simulated test device from 150℃ and maintain it at the accelerated aging temperature of 220℃ (not lower than the typical operating temperature of Pegasus II lubricating oil of 200℃, and not higher than the maximum temperature that FX-17 fluororubber sealing ring material can withstand during operation of 250℃ (as specified in the material manual)). Use an external oil pump to pressurize the Pegasus II lubricating oil in the simulated test device to maintain its pressure value at the typical pressure value of 0.5MPa when the aircraft engine is operating. Test for 4 hours under the conditions of 0.5MPa and 220℃.

[0057] Sub-step 2): Cooling and depressurization

[0058] Adjust the STPH-102 high-temperature test chamber to lower the ambient temperature of the simulated test device from 220℃ to room temperature, and manually open the pressure relief valve to reduce the pressure of the Pegasus II lubricating oil in the simulated test device to 0MPa. After the cooling and depressurization process (sub-step 2) is completed, immediately repeat the high-temperature pressurization process (sub-step 1), and repeat this cycle until the accelerated aging of the simulated working environment (step 2) reaches the preset "high-temperature pressurization + cooling and depressurization" cycle 250 times (corresponding to 250 times of operation per year for an aero-engine), or until the pressure value of the Pegasus II lubricating oil during high-temperature pressurization is lower than the lower limit of its normal operating range by 0.3MPa.

[0059] After the accelerated aging under simulated working conditions (step 2) is completed, the accelerated aging under simulated parking conditions (step 1) is immediately repeated. This process is repeated until the entire accelerated aging test reaches the preset total number of cycles of 10 (corresponding to 10 calendar years when the first overhaul period of the aircraft engine is 10,000 hours and the annual working hours are 1,000 hours), or the pressure value of the Pegasus II lubricating oil under high temperature pressure is lower than the lower limit of its normal working range by 0.3 MPa. The test ends then.

Claims

1. A method for accelerated aging test of rubber seals simulating the service environment of an aircraft engine, characterized in that, A simulation test device with a pressure relief valve is designed based on the actual sealing structure's rubber sealing ring assembly dimensions, component materials, surface treatment processes, and medium pressure. Install the rubber sealing ring in the sealing ring groove of the simulation test device; The medium required for sealing the actual sealing structure is injected into the simulation test device, and the medium is placed under natural atmospheric pressure; the simulation test device is then placed in a high-temperature test chamber in preparation for the test. Then, an accelerated aging test was conducted using a cyclical test method consisting of two test steps: accelerated aging under simulated parking conditions and accelerated aging under simulated working conditions. Step 1: Simulate accelerated aging in the parking environment Maintain the medium pressure in the simulation test apparatus at 0 MPa, and adjust the high-temperature test chamber to raise and maintain the ambient temperature of the simulation test apparatus at ambient temperature T. p The test was conducted for 120 to 720 hours under these ambient temperature and medium pressure conditions. Step 2: Simulated accelerated aging under working conditions Accelerated aging under simulated operating conditions is a cyclic test consisting of two sub-steps: 1) High-temperature pressure testing Adjust the high-temperature test chamber to simulate the ambient temperature T of the test device. p Increase and maintain the accelerated aging temperature T w A medium pump is used to pressurize the medium in the simulation test device, maintaining the medium pressure at the typical pressure value P during the operation of an aero-engine. w At accelerated aging temperature Tw and medium pressure P w Under the conditions, the test lasted from 1 hour to 6 hours; 2) Cooling and depressurization Adjust the high-temperature test chamber to reduce the ambient temperature of the simulated test device from the accelerated aging temperature T. w The pressure was reduced to room temperature, and the pressure of the medium in the simulation test device was reduced from P through the pressure relief valve. w After the pressure drops to 0 MPa and the cooling and depressurization step 2) is completed, immediately repeat the high-temperature pressurization step 1), and continue this cycle until the accelerated aging of the simulated working environment reaches the preset number of "high-temperature pressurization + cooling and depressurization" cycles N. w Or P during high temperature and pressure w Until it can no longer be maintained within the normal operating range of the media system; After the accelerated aging step 2 under simulated working conditions is completed, immediately repeat the accelerated aging step 1 under simulated parking conditions. Continue this cycle until the entire accelerated aging test reaches the preset total number of cycles N, or the high-temperature pressure test P. w The test ends when the system can no longer maintain its normal operating range.

2. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine as described in claim 1, characterized in that, Step 1, which simulates accelerated aging in a parking environment, is used to simulate the natural environmental aging effects accumulated on the rubber seals of an aircraft engine during its one-year service life while it is parked.

3. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine as described in claim 1, characterized in that, The accelerated aging temperature T in step 1 p Temperatures should be above ambient temperature and at least 20°C below the typical operating temperature of the medium.

4. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine as described in claim 1, characterized in that, Step 2, simulating accelerated aging under working conditions, is used to simulate the aging effect of the rubber seals accumulated under working conditions during the one-year service period of an aero-engine.

5. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine according to claim 1, characterized in that, In step 1), the accelerated aging temperature T w The temperature should not be lower than the typical operating temperature of the medium, and should not be higher than the maximum temperature that the rubber sealing ring material can withstand during operation.

6. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine according to claim 1, characterized in that, In step 1), the booster pump is matched with the specific medium type, such as air, fuel oil, or lubricating oil.

7. The accelerated aging test method for rubber seals simulating the service environment of an aircraft engine according to claim 1, characterized in that, The typical pressure value P during the operation of the aero-engine in step 1) is mentioned above. w This refers to a specific pressure value within the normal operating range of a particular media system, such as an air system, fuel system, or lubricating oil system.

8. The accelerated aging test method for rubber seals simulating the service environment of an aircraft engine according to claim 1, characterized in that, The number of cycles N for "high-temperature pressurization + cooling and depressurization" in step 2) is as follows. w The range is set to 100 to 400 times, corresponding to the number of times an aero engine operates per year.

9. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine according to claim 1, characterized in that, The total number of accelerated aging tests, N, is set to 3 to 15 times, corresponding to the number of calendar years when the aero-engine reaches its first overhaul period.

10. The accelerated aging test method for rubber seals simulating the service environment of an aero-engine according to claim 1, characterized in that, The assembly dimensions of the rubber sealing ring in the sealing structure include: the cross-sectional shape, depth, width, and sealing gap of the sealing ring groove.