An aero-engine compressor blade service damage evaluation method

Abstract

This invention relates to a method for evaluating service damage of aero-engine compressor blades, solving the problem that current blade performance testing cannot obtain test values ​​'d' through direct sampling from the blade. The method comprises the following steps: S1: Design the dimensions of the blade simulator; S2: Select a base material consistent with the blade; S3: Calculate the maximum temperature and maximum stress of the blade under different service conditions, based on the blade's design status; S4: Statistically count the number of Category I low-cycle cycles, Category III flight takeoff cycles, and Category IV powered takeoff cycles for at least 10 engines, and calculate the conversion factors for each type of cycle using the temperature and stress calculation values ​​under different service conditions to obtain the equivalent number of cycles for different service times; S5: Apply low-cycle fatigue loading, fixing and clamping the simulator, and performing low-cycle cyclic loading according to the stated temperature, stress, and number of cycles; S6: Take samples from the low-cycle fatigue-treated specimen and perform tensile and high-cycle fatigue mechanical property tests. This invention significantly reduces the need for collecting blade service conditions and parameters, greatly reducing workload.

Description

Technical Field

[0001] This invention relates to the field of aircraft engine maintenance, and in particular to a method for evaluating service damage to aircraft engine compressor blades. Background Technology

[0002] Compressor blades are key components of aero-engines, enduring the complex combined effects of centrifugal force, aerodynamic forces, vibration loads, and high temperatures during service. As service time increases, the performance of the blade matrix material gradually declines. However, because blades are thin-walled components, performance tests such as monotonic tensile testing, high-cycle fatigue performance, and fatigue crack propagation cannot be obtained by directly sampling from the blade. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-cycle fatigue test method that can quickly and accurately simulate the temperature, stress state and loading path of compressor blades under real service conditions, thereby achieving accurate assessment of their fatigue life.

[0004] The objective of this invention is achieved through the following technical solution: A method for evaluating service damage of aero-engine compressor blades includes the following steps: S1: Design the dimensions of the simulated component. The equivalent design parts of the simulated component have similar geometry to the corresponding parts of the actual blade. The dimensions of key blade components are equivalent.

[0005] S2: Select a base material that is consistent with the technical requirements such as the material state and heat treatment of the blade.

[0006] S3: Equivalent Design Load. Based on the blade design conditions, calculate the highest temperature and maximum stress of the blade under different service conditions.

[0007] S4: Statistically count the Category I low cycle number, Category III flight takeoff cycle, and Category IV powered takeoff cycle of no less than 10 engines. Calculate the conversion factor for each type of cycle using temperature stress calculation values ​​under different service conditions to obtain the equivalent cycle number for different service times.

[0008] S5: Low-cycle fatigue loading, fix the simulated part, and perform low-cycle cyclic loading according to the temperature, stress, and number of cycles described in steps S2 and S3.

[0009] S6: Take samples from the specimens after low-cycle fatigue treatment and perform tensile and high-cycle fatigue mechanical property tests.

[0010] The beneficial effects of this invention are: 1. To address the issue of not being able to sample and assess the mechanical properties of materials after service, a simulated equivalent component is designed to evaluate the evolution of material mechanical properties during different service cycles.

[0011] 2. Using design conditions to fabricate simulated parts can greatly reduce the need to collect data on the service conditions and parameters of the blades, thus significantly reducing the workload. Attached Figure Description

[0012] Figure 1 The blade is equivalent to a flat plate sample. Detailed Implementation

[0013] This invention is a method for evaluating the changes in mechanical properties caused by cumulative damage during service of aero-engine compressor blades with complex profiles.

[0014] During engine service, the main degradation mechanisms of components are low-cycle fatigue caused by the superposition of thermal and mechanical stresses during takeoff, cruise, and landing, and creep damage caused by the high-temperature, high-stress steady-state cruise phase of the blades. Since high-pressure compressor blades are cold-end blades with low operating temperatures, creep is essentially nonexistent. Therefore, when simplifying the model, creep damage during the high-temperature, high-stress steady-state cruise phase does not need to be considered. The mechanical properties of the blades in service are tested by analyzing the low-cycle cycle conditions during service.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0016] S1: Design of the simulated component dimensions. For a compressor blade with a complex torsional profile designed for 425 hours of service, this test aims to evaluate the changes in the blade's mechanical properties after use. The blade is modeled as a flat plate specimen. Because tensile properties need to be tested, the flat plate dimensions are designed to be 46mm × 12mm × 2mm. See [details omitted]. Figure 1 .

[0017] S2: Select TA11 as the matrix material, which is consistent with the material state and technical requirements of the blade.

[0018] S3: Equivalent Design Load. Based on the blade design conditions, calculate the highest blade temperature, maximum stress, and cumulative low-cycle fatigue damage under different service conditions and service cycles. The highest temperature is 358℃, and the maximum average stress on the blade is 347MPa. Figure 1 Finite element analysis of the specimen showed that an application of F = 11.3 kN was required to ensure that the stress in the middle of the specimen was 347 MPa.

[0019] S4: The average number of Category I low-cycle cycles for 15 engines was 365, Category III flight takeoff cycles was 803, and Category IV powered takeoff cycles was 1569. The conversion factor for each type of cycle was calculated using the temperature stress calculation values ​​under different service conditions, resulting in an equivalent number of 605 cycles for different service times.

[0020] S5: Low-cycle fatigue loading. Because the compressor blades operate at low temperatures, there is no need to consider damage caused by creep. Therefore, the simulated part is fixedly clamped on a tensioning device, and low-cycle cyclic loading is performed according to the above temperature, stress, and number of cycles.

[0021] S6: Take samples from the specimens after low-cycle fatigue treatment and perform tensile and high-cycle fatigue mechanical property tests.

Claims

1. A method for evaluating service damage of aero-engine compressor blades, characterized in that: The method steps are as follows: S1: Design the dimensions of the simulation part. The geometric shape of the equivalent design part of the simulation part is similar to that of the corresponding part of the real blade. The dimensions of the key parts of the blade are equivalent. S2: Select a base material that is consistent with the blade material condition and heat treatment technology requirements; S3: Design load equivalent, combined with blade design state, calculate the highest blade temperature, maximum stress and cumulative low-cycle fatigue damage under different service conditions; S4: Statistically count the number of Category I low-cycles, Category III flight takeoff cycles, and Category IV powered takeoff cycles for no less than 10 engines. Calculate the conversion factor for each type of cycle using temperature stress calculations under different service conditions to obtain the equivalent number of cycles for different service times. S5: Low-cycle fatigue loading, fix the simulated part, and perform low-cycle cyclic loading according to the temperature, stress and number of cycles described in steps S2 and S3; S6: Take samples from the specimens after low-cycle fatigue treatment and perform tensile and high-cycle fatigue mechanical property tests.

2. The method for evaluating service damage of aero-engine compressor blades according to claim 1, characterized in that: in step S1, for compressor blades that have been in service for 425 hours, in order to evaluate the changes in the mechanical properties of the blade body after use, the blade body is equivalent to a flat plate sample.

3. The method for evaluating service damage of aero-engine compressor blades according to claim 2, characterized in that: To test the tensile properties, the flat plate specimen was designed with dimensions of 46mm × 12mm × 2mm.

4. The method for evaluating service damage of aero-engine compressor blades according to claim 1, characterized in that: In step S3, the highest temperature is 358°C and the maximum average stress on the blade is 347 MPa.

5. The method for evaluating service damage of aero-engine compressor blades according to claim 1, characterized in that: In step S4, the average number of Category I low-cycle cycles (365), Category III flight takeoff cycles (803), and Category IV powered takeoff cycles (1569) for 15 engines are statistically analyzed. The conversion factor for each type of cycle is calculated using the temperature stress calculation values ​​under different service conditions, resulting in an equivalent number of cycles (605) for different service times.

6. The method for evaluating service damage of aero-engine compressor blades according to claim 5, characterized in that: In step S5, low-cycle cyclic loading is performed according to the stated temperature, stress, and number of cycles.

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