Aerospace engine nozzle flap repeated life test method

Abstract

The application discloses a kind of aerospace engine nozzle regulating piece repeated life examination test methods.The described method is respectively to test sample medium-tail gas-load-temperature environment examination test and tail gas-load-temperature environment examination test: the cycle of above-mentioned two tests obtains a big cycle, after each big cycle ends, the performance of test sample is detected according to failure criterion and fitting curve, when the life index of test sample drops below failure criterion, the number of cycle test is obtained according to the fitting curve, the repeated life under different failure criterion is calculated according to the number of cycle test, select the shortest one as repeated life.The application realizes the repeated life evaluation of military aircraft nozzle regulating piece by medium-tail gas-load-temperature environment examination test and tail gas-load-temperature environment examination test, guarantees the service safety of aerospace equipment and makes the life of regulating piece to be fully played.

Description

Technical Field

[0001] This invention relates to the field of performance testing technology, specifically to a test method for repeated life assessment of nozzle adjustment vanes in aerospace engines. Background Technology

[0002] Nozzle trimmers are primarily used in aerospace engines with afterburners. They are a highly technologically advanced and critical hot-end component of military aero engines, located at the very rear of the engine nozzle, serving as the final "gateway" for the high-temperature exhaust gases into the atmosphere. Integrating aerodynamic regulation, thermal management, and stealth design, their performance directly affects the engine's thrust, efficiency, safety, and the aircraft's stealth capabilities. Their design and manufacturing level is a key indicator of a nation's aero-engine technological strength. Previously, high-temperature alloys (such as nickel-based alloys) were commonly used for nozzle trimmers to cope with the extremely high temperatures (up to 1700-2000°C) generated by the afterburner. However, to reduce weight and improve the performance and combat effectiveness of aero-engines, new inorganic composite materials are now used for nozzle trimmers.

[0003] The environmental conditions experienced by nozzle control vanes during service are extremely harsh couplings of multiple physical fields, especially for military aircraft where the service conditions can be described as "hell mode." First, in the ground parking environment, nozzle control vanes are subjected to humid heat, rain, salt spray, and gas corrosion. Second, throughout the entire flight envelope, the engine status is constantly changing (takeoff, climb, cruise, dogfighting, afterburner on / off, landing). Each afterburner on / off means that the control vane has to undergo a violent heating-holding-cooling cycle (low-cycle thermal fatigue), which leads to fatigue cracks and is a great test of the material's lifespan. Third, the high-temperature exhaust gas has a very high pressure, generating huge aerodynamic loads on the control vane surface, attempting to deform it. Finally, the exhaust gas from the afterburner is extremely hot and contains corrosive components such as nitrogen oxides, sulfides, and carbon monoxide. At extremely high temperatures, these corrosive components react with the elements in the control vane material, causing continuous oxidation and corrosion of the material surface, reducing the effective cross-section, and degrading performance. These performance changes limit the lifespan of the nozzle control vane, requiring periodic replacement throughout the equipment's service life.

[0004] To ensure the safe operation of aerospace equipment and maximize the lifespan of nozzle control vanes, their repeatable service life must be evaluated. Currently, there is no suitable testing method for assessing the lifespan of military aircraft nozzle control vanes. Therefore, it is necessary to design a repeatable service life assessment method suitable for military aircraft nozzle control vanes to achieve repeatable service life evaluation, ensuring the safe operation of aerospace equipment and maximizing the lifespan of the control vanes. Summary of the Invention

[0005] In view of the above-mentioned prior art, the purpose of this invention is to provide a method for repeated life assessment of nozzle control vanes in aerospace engines. This invention achieves repeated life assessment of nozzle control vanes in military aircraft through medium-exhaust gas-load-temperature environment assessment tests and exhaust gas-load-temperature environment assessment tests, ensuring the service safety of aerospace equipment and maximizing the lifespan of the control vanes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A first aspect of the present invention provides a method for repeated life testing of nozzle trimmers in aerospace engines, comprising the following steps: (1) Medium-exhaust gas-load-temperature environment test: First, the sample to be tested is subjected to a medium treatment test, then the sample to be tested is subjected to high temperature treatment and mechanical load is applied, and then it is naturally cooled; (2) Exhaust gas-load-temperature environment test: The sample to be tested is subjected to high temperature treatment and mechanical load, and then naturally cooled; (3) Performing a cyclic test according to the methods in steps (1) and (2) constitutes one large cycle. After each large cycle, the performance of the sample under test is tested according to the failure criteria and the curve is fitted. When the lifetime index of the sample under test drops below the failure criteria, the exact number of large cycles is obtained according to the fitted curve. The repeatability lifetime under different failure criteria is calculated according to the exact number of large cycles, and the one with the shortest lifetime is selected as the repeatability lifetime.

[0007] Preferably, in step (1), the medium treatment test includes at least one of rain test, damp heat test, salt spray test, and gas corrosion test.

[0008] Preferably, the rain test is conducted with raindrop diameters of 1.1–5.0 mm, rainfall intensity of 1.2–25 mm / h, accompanying wind speed of 5.5–17.8 m / s, and rain duration of 0–3.5 h. The damp heat test is as follows: the damp heat test temperature is 30-90℃, the humidity is 55-95%RH, and the test duration is 24-480h; The salt spray test was conducted with droplet diameters of 0.1–20 μm and salt spray concentrations of 1–50 mg / m³. 3 The test temperature is 30–65℃, and the test duration is 8–240 hours. The gas corrosion test is conducted using at least one of the following gases: sulfur oxides, sulfides, carbon oxides, nitrogen oxides, ozone, chlorides, fluorides, and hydrogen, with a concentration of 0.2–10 mg / m³. 3 The test temperature is 30–55℃ and the test duration is 0.5–240h.

[0009] Preferably, in step (1), the temperature of the high-temperature treatment is raised from room temperature to 600-2000℃ at a heating rate of 1-10℃ / s, and held for 0.5-24h; the pressure of the mechanical load is 0-500MPa; and the cooling is natural cooling to room temperature to 800℃.

[0010] Preferably, in step (2), the temperature of the high-temperature treatment is raised from room temperature to 600-2000℃ at a heating rate of 1-10℃ / s and held for 0.5-24 h; the pressure of the mechanical load is 0-500MPa; and the cooling is natural cooling to room temperature to 800℃.

[0011] The type of medium test should be selected based on the climate environment of the service area: salt spray test is required for coastal or offshore service, rain test is required for rainy seasons or rainy areas, gas corrosion test is required for industrial pollution areas, and damp heat test is required for hot and humid climates in the south. Tests can be superimposed based on the complexity of the climate environment of the service area.

[0012] Preferably, in step (3), the failure criteria include an increase in volume shrinkage rate, an increase in thermal conductivity, a decrease in flexural strength, a decrease in tensile strength, a decrease in normal compressive strength, and a decrease in in-plane compressive strength.

[0013] Preferably, the test sample is deemed to have failed and the cyclic test ends when it first reaches at least one of the following: volume shrinkage rate increases by ≥2%, thermal conductivity increases by ≥25%, flexural strength decreases by ≥30%, tensile strength decreases by ≥40%, normal compressive strength decreases by ≥40%, or in-plane compressive strength decreases by ≥40%.

[0014] Preferably, in step (3), the ratio of the number of cycles in step (1) to step (2) is 1:5~20.

[0015] Preferably, in step (3), the repetitive lifetime = (1 + 5 ~ 20) × the exact number of large cycles.

[0016] In a second aspect, the present invention provides an application of a test method for the repeated life assessment of nozzle trimmers in aerospace engines in improving the accuracy of repeated life testing of nozzle trimmers.

[0017] The beneficial effects of this invention are: (1) This invention achieves repeated life assessment of the nozzle adjustment plate of military aircraft through medium-exhaust gas-load-temperature environment test and exhaust gas-load-temperature environment test, ensuring the service safety of aerospace equipment and making full use of the life of the adjustment plate.

[0018] (2) The failure criteria (test methods and conditions) of this invention are based on a survey of the service environment of military aircraft to identify the main corrosive environmental factors experienced under ground parking conditions, including annual average temperature and humidity, annual rainfall parameters, atmospheric salt spray content, and the composition and content of corrosive gases. Climate simulation test conditions are then determined based on the climate parameters obtained from the survey. Next, engine parameters, including power, fuel type, air-fuel ratio, and fuel injection quantity, are investigated and confirmed. Simulation input parameters for exhaust gas composition are determined based on the engine parameters obtained from the survey. Simultaneously, simulation calculations of engine exhaust gas composition and the maximum temperature of the regulating plate are performed, or the engine exhaust gas composition and the maximum temperature of the regulating plate are obtained through detection methods. Then, repeated life tests of the engine regulating plate are conducted, and various properties of the material are continuously tested, including thermal insulation performance, mechanical properties, dimensional changes, and mass changes. This provides guidance for calculating the lifespan of aerospace engine nozzle regulating plates. Attached Figure Description

[0019] Figure 1 Example 1: The change in thermal conductivity of the regulating plate with the number of cycles and the fitting curve; Figure 2 Example 1: Changes in the normal compressive strength of the adjustment plate with the number of cycles and the fitted curve; Figure 3 Example 1: The variation and fitting curve of the compressive strength within the adjustment surface with the number of cycles; Figure 4 Example 2: The change in the volume shrinkage rate of the regulating plate with the number of cycles; Figure 5 The thermal conductivity of the regulating plate in Example 2 changes with the number of cycles; Figure 6 Example 2: Adjustment of the in-plane compressive strength as a function of the number of cycles and the fitted curve; Figure 7 : Schematic diagram of the test procedure. Detailed Implementation

[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0021] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0022] The test materials used in the embodiments of this invention are all conventional test materials in the art and can be purchased through commercial channels.

[0023] Example 1: Repeatability test of a tail nozzle regulating plate of a military aircraft made of a silica fiber reinforced silica / alumina composite material (Si-Al). The operating conditions consist of two types: rain-load-temperature cycle and load-temperature cycle.

[0024] (1) Sample preparation: Thermal conductivity test is a non-destructive test, so prepare 3 samples for repeated use. After each test, take the average value as the thermal conductivity data. The sample size is 150×150×10mm. Normal compressive strength and in-plane compressive strength are destructive tests. Therefore, without knowing the specific number of tests, prepare a reconstituted sample quantity. Prepare 15 batches of normal compressive strength and in-plane compressive strength samples, with 5 samples in each batch. After each test, take the average value as the strength data. The sample size is 25×25×25mm.

[0025] (2) The test method of rain-load-temperature cycle is as follows: a sample of a military aircraft tail nozzle adjustment plate made of silica fiber reinforced silica / alumina composite material (Si-Al) is subjected to rain test for 0.5h (rain test conditions are: raindrop diameter is 1.1~2.5mm, rainfall intensity is 1.2~12mm / h, and wind speed is 5.5~7.8m / s). Then the sample is moved to the high temperature test device and an in-plane normal load of 70MPa is applied to the sample. The sample is heated from room temperature to 900℃ at a heating rate of 10℃ / s under simulated engine exhaust environment conditions. It is kept at 900℃ for 0.5h and then naturally cooled to room temperature.

[0026] (3) The test conditions for load-temperature cycling are as follows: under the engine exhaust gas environment under the load condition of 70MPa, the sample is heated from room temperature to 900℃ at a heating rate of 10℃ / s, kept at 900℃ for 0.5h, and then naturally cooled to room temperature.

[0027] (4) The rain-load-temperature test in step (2) was conducted once, and the load-temperature test in step (3) was conducted 5 times to achieve one large cycle. After each large cycle, the volume shrinkage rate, thermal conductivity, flexural strength, tensile strength, normal compressive strength, and in-plane compressive strength were tested according to the failure criteria. It was found that the volume shrinkage rate, flexural strength, and tensile strength changed very little, while the thermal conductivity, normal compressive strength, and in-plane compressive strength changed significantly. Therefore, thermal conductivity, normal compressive strength, and in-plane compressive strength were used as failure criteria. The data after testing are shown in Table 1. A total of 10 large cycles were conducted.

[0028] The failure criteria are as follows: thermal conductivity ≤ 0.85 W / (m•K) or rate of increase ≤ 25%; normal compressive strength ≤ 110 MPa or decrease ≥ 40%; in-plane compressive strength ≤ 70 MPa or decrease ≥ 40%.

[0029] Table 1 Performance test data during cyclic testing Based on the above test results, scatter plots of thermal conductivity, normal compressive strength, and in-plane compressive strength as a function of the number of cycles were plotted, and a mathematical model of the data scatter plots was fitted using data processing software.

[0030] As shown in Table 1, the thermal conductivity is 0.85 W / (m•K) after the 9th large cycle, representing an increase of >25%. The data points in Table 1 were fitted using Excel (by calling the fitting command in the software, selecting the fitting function type, and the software automatically fitting the curve), resulting in... Figure 1 The mathematical model for the fitted curve is y = 0.0001x. 4 +0.004x 3 -0.0234x 2 -0.02x+0.5251, where the horizontal axis represents the number of large cycles N, and the vertical axis represents the thermal conductivity. The calculation shows that the number of cycles required for the thermal conductivity failure criterion to reach 0.85 W / (m•℃) is 9.3 large cycles. The repeatability life is calculated as 9.3 × (n1 + n2). Therefore, the lifespan with thermal conductivity as the failure criterion is 9.3 large cycles, which translates to a repeatability lifespan of 9.3 × (1 + 5) = 56 cycles, meaning it can withstand at least 56 takeoffs and landings.

[0031] Table 1 shows that the normal compressive strength was greater than 110 MPa after ten cycles, not exceeding the normal compressive strength failure criterion of ≤110 MPa. By fitting the data points in Table 1 using Excel, we obtained... Figure 2 The fitted curve is y = 26.17x + 387.3, where the horizontal axis represents the number of large cycles N, and the vertical axis represents the normal compressive strength. The number of cycles required for the normal compressive strength failure criterion to reach 110 MPa is calculated to be 10.6 large cycles. Therefore, the service life using normal compressive strength as the failure criterion is 10.6 large cycles, or a repeatability life of 10.6 × (1 + 5) = 64 cycles, meaning it can withstand at least 64 takeoffs and landings.

[0032] As shown in Table 1, the in-plane compressive strength reached 70 MPa after the 5th cycle. This exceeds the failure criterion of in-plane compressive strength ≤ 70 MPa. By fitting the data points in Table 1 using Excel, we obtained... Figure 3The fitted curve is y = -12.385x + 135, where the horizontal axis represents the number of large cycles N, and the vertical axis represents the in-plane compressive strength. The curve intercepts the failure criterion of in-plane compressive strength reaching 70 MPa, which is 5.3 large cycles. Therefore, the service life with in-plane compressive strength as the failure criterion is 5.3 large cycles, that is, the repeatability life is 5.3 × (1 + 5) = 32 cycles, meaning it can be used for at least 32 takeoffs and landings.

[0033] Based on safety principles, it is recommended to use the shortest life among the three failure criteria as the repeatability life of the tail nozzle control plate material. Therefore, the shortest life is when the in-plane compressive strength is used as the failure criterion, with a repeatability life of 32 times, which means it can be used for at least 32 takeoffs and landings.

[0034] Example 2: Repeatability test of a certain type of silica aerogel conditioning sheet (Si-g) (1) Sample preparation: Thermal conductivity test is a non-destructive test, so prepare 3 samples for repeated use. After each test, take the average value as the thermal conductivity data. The sample size is 150×150×10mm. Normal compressive strength and in-plane compressive strength are destructive tests. Therefore, without knowing the specific number of tests, prepare a reconstituted sample quantity. Prepare 15 batches of normal compressive strength and in-plane compressive strength samples, with 5 samples in each batch. After each test, take the average value as the strength data. The sample size is 25×25×25mm.

[0035] (2) The test method for damp heat-salt spray-load-temperature cycling is as follows: The sample is first subjected to a damp heat test at a temperature of 30–90℃ and a humidity of 55–95%RH for 240 hours. Then, a salt spray test is conducted with a droplet diameter of 0.1–20 μm and a salt spray concentration of 1–50 mg / m³. 3 The test temperature was 30–65℃, and the test duration was 96 hours. The sample was then moved to a high-temperature test device, and heated from room temperature to 1200℃ at a rate of 5℃ / s under simulated engine exhaust gas conditions. The sample was held at 1200℃ for 1 hour and then allowed to cool naturally to room temperature. (3) The test conditions for load-temperature cycling are as follows: Under the engine exhaust environment, the sample is heated from room temperature to 1200℃ at a heating rate of 5℃ / s, kept at 1200℃ for 1h, and then naturally cooled to room temperature.

[0036] (4) A single damp heat-salt spray-load-temperature test was conducted, and a two-cycle load-temperature cyclic test was performed to achieve one large cycle. A total of 20 large cycles were performed. After each large cycle, the sample's volume shrinkage rate, thermal conductivity, flexural strength, tensile strength, normal compressive strength, and in-plane compressive strength were measured. It was found that the normal compressive strength, flexural strength, and tensile strength decreased very little, while the thermal conductivity, volume shrinkage rate, and in-plane compressive strength changed significantly. The failure criteria were: thermal conductivity ≥ 0.16 W / (m•℃); volume shrinkage rate ≥ 2%; in-plane compressive strength ≤ 1.5 MPa. The thermal conductivity, volume shrinkage rate, and in-plane compressive strength were as follows: Figures 4-6 As shown.

[0037] Figure 4 To illustrate the change in volume shrinkage rate of Si-g with the number of cycles, a curve y = 0.127x + 0.4311 was fitted to the obtained values, where the horizontal axis represents the number of large cycles N, and the vertical axis represents the volume shrinkage rate. After the 12th large cycle, the volume shrinkage rate of Si-g is 1.92%, close to the volume shrinkage failure criterion of ≥2%. Therefore, the number of cycles required for the volume shrinkage failure criterion to reach 2% is 12 large cycles. Thus, the lifetime with volume shrinkage rate as the failure criterion is 12 large cycles, or a repeatability lifetime of 12 × (1 + 2) = 36 cycles, meaning it can be used for at least 36 takeoffs and landings.

[0038] The change of Si-g cyclic thermal conductivity with the number of cycles is as follows: Figure 5 As shown, thermal conductivity fluctuates with the number of cycles. The failure criterion was not reached after 20 cycles because volume shrinkage had already reached the failure criterion, so it is not necessary to calculate the repeatability life based on thermal conductivity as the failure criterion.

[0039] The change in compressive strength with the number of cycles and the fitted curve are as follows: Figure 6 As shown, the compressive strength fluctuates with the increase of the number of cycles in the early stage, and decreases with the increase of the number of cycles in the later stage. The failure criterion was not reached after 20 cycles because the volume shrinkage had already reached the failure criterion, so it is not necessary to calculate the repeated life based on the thermal conductivity as the failure criterion.

[0040] Based on safety principles, it is recommended to use the shortest life among the three failure criteria as the material's repeatability life. The shortest life is when the volume shrinkage rate is used as the failure criterion, which is 12 cycles, or 36 repeatability life, meaning it can be used for at least 36 takeoffs and landings.

[0041] Example 3: Verification of Experimental Methods The tail nozzle regulating vane of a certain military aircraft, made of silica fiber-reinforced silica / alumina composite material (Si-Al) as described in Example 1, has been in service on dozens of military aircraft of a certain model. Through maintenance, inspection, and analysis of the regulating vanes on 10 of these aircraft, it was found that the regulating vanes on 2 aircraft deformed after 34 takeoffs and landings, failing to meet the exhaust gas regulation technical requirements and should be replaced. Therefore, the service life of the regulating vanes on these two aircraft was 34 takeoffs and landings. The regulating vanes on 3 other aircraft showed volume shrinkage after 35 takeoffs and landings, also failing to meet the exhaust gas regulation technical requirements and should be replaced. Replacement was performed, therefore, the service life of the control plates on these two military aircraft was 35 takeoffs and landings. For the other five military aircraft, after 37 takeoffs and landings, the volume shrinkage and deformation of the control plates met the exhaust gas regulation technical requirements. However, testing of their compressive strength revealed that their normal strengths were 105 MPa, 103 MPa, 107 MPa, 110 MPa, and 106 MPa respectively, which no longer met the technical requirement of ≤110 MPa. This indicates a high risk of insufficient mechanical performance and damage to the control plates during flight. Therefore, the service life of the control plates on these five military aircraft was 37 takeoffs and landings. Verification of the control plates after actual service shows that the error between the method in Example 1 and the actual service life is 6.25%–15.6%, therefore the method is accurate and effective.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A test method for repeated life assessment of nozzle trimmers in aerospace engines, characterized in that, Includes the following steps: (1) Medium-exhaust gas-load-temperature environment test: First, the sample to be tested is subjected to a medium treatment test, then the sample to be tested is subjected to high temperature treatment and mechanical load is applied, and then it is naturally cooled; (2) Exhaust gas-load-temperature environment test: The sample to be tested is subjected to high temperature treatment and mechanical load, and then naturally cooled; (3) Performing a cyclic test according to the methods in steps (1) and (2) constitutes one large cycle. After each large cycle, the performance of the sample under test is tested according to the failure criteria and the curve is fitted. When the lifetime index of the sample under test drops below the failure criteria, the exact number of large cycles is obtained according to the fitted curve. The repeatability lifetime under different failure criteria is calculated according to the exact number of large cycles, and the one with the shortest lifetime is selected as the repeatability lifetime.

2. The test method for repeated life assessment of aerospace engine nozzle adjustment vanes according to claim 1, characterized in that, In step (1), the medium treatment test includes at least one of the following: rain test, damp heat test, salt spray test, and gas corrosion test.

3. The test method for repeated life assessment of aerospace engine nozzle adjustment vanes according to claim 2, characterized in that, The rain test was conducted with raindrop diameters of 1.1–5.0 mm, rainfall intensity of 1.2–25 mm / h, accompanying wind speeds of 5.5–17.8 m / s, and a duration of 0–3.5 h. The damp heat test is as follows: the damp heat test temperature is 30-90℃, the humidity is 55-95%RH, and the test duration is 24-480h; The salt spray test is: mist droplet diameter is 0.1-20 μm, salt spray concentration is 1-50 mg / m 3 , test temperature is 30-65 °C, test duration is 8-240 h; The gas corrosion test is conducted using at least one of the following gases: sulfur oxides, sulfides, carbon oxides, nitrogen oxides, ozone, chlorides, fluorides, and hydrogen, with a concentration of 0.2–10 mg / m³. 3 The test temperature is 30–55℃ and the test duration is 0.5–240h.

4. The test method for repeated life assessment of aerospace engine nozzle trimmers according to claim 1, characterized in that, In step (1), the high temperature treatment is performed at a heating rate of 1 to 10 °C / s from room temperature to 600 to 2000 °C and held at that temperature for 0.5 to 24 hours; the mechanical load pressure is 0 to 500 MPa; and the cooling is performed by natural cooling to room temperature to 800 °C.

5. The test method for repeated life assessment of aerospace engine nozzle adjustment vanes according to claim 1, characterized in that, In step (2), the temperature of the high-temperature treatment is raised from room temperature to 600-2000℃ at a heating rate of 1-10℃ / s and held for 0.5-24h; the pressure of the mechanical load is 0-500MPa; and the cooling is natural cooling to room temperature to 800℃.

6. The test method for repeated life assessment of aerospace engine nozzle trimmers according to claim 1, characterized in that, In step (3), the failure criteria include an increase in volume shrinkage rate, an increase in thermal conductivity, a decrease in flexural strength, a decrease in tensile strength, a decrease in normal compressive strength, and a decrease in in-plane compressive strength.

7. The test method for repeated life assessment of aerospace engine nozzle trimmers according to claim 6, characterized in that, The test sample is deemed to have failed if it first reaches at least one of the following: volume shrinkage rate increases by ≥2%, thermal conductivity increases by ≥25%, flexural strength decreases by ≥30%, tensile strength decreases by ≥40%, normal compressive strength decreases by ≥40%, or in-plane compressive strength decreases by ≥40%. The cyclic test then ends.

8. The test method for repeated life assessment of aerospace engine nozzle trimmers according to claim 1, characterized in that, In step (3), the ratio of the number of cycles in step (1) to the number of cycles in step (2) is 1:5~20.

9. The test method for repeated life assessment of aerospace engine nozzle trimmers according to claim 1, characterized in that, In step (3), the repetitive lifetime = (1 + 5 ~ 20) × the exact number of large cycles.

10. The application of the test method for repeated life assessment of aerospace engine nozzle trimmers according to any one of claims 1 to 9 in improving the accuracy of repeated life testing of nozzle trimmers.

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