Engine centrifugal impeller simulation sample high-temperature corrosion environment tension-bending composite fatigue test device and method

Abstract

The application discloses a high-temperature corrosion environment tensile-bending composite fatigue test device and method for engine blade (centrifugal impeller) simulation samples, which comprises an axial load system, a transverse vibration system, a temperature control system and a measurement system. The axial load system applies axial tensile-tensile load to the simulation sample through a pin, the transverse vibration system provides transverse bending vibration load for the simulation sample, and the temperature control system provides the temperature of the engine real working environment for the simulation sample examination part. Meanwhile, according to the tensile-bending composite fatigue test requirement, the simulation sample is designed according to the local position load of the engine blade (centrifugal impeller), and the salt spray spraying / deposition method is adopted on the sample surface to simulate the marine salt spray corrosion environment, so that the real stress, temperature and corrosion environment of the engine are accurately reflected, and the test can more accurately simulate the tensile-bending composite fatigue condition of the dangerous part in the working process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanical testing equipment, and particularly relates to a high-temperature corrosion environment tensile-bending combined fatigue test device and method for engine centrifugal impeller simulation samples. BACKGROUND

[0002] As an important component of turboshaft engines, the engine centrifugal impeller can ensure the stable and reliable operation of the turboshaft engine and the helicopter. At present, the engine is developing towards higher temperature, higher speed and more stability, and more and more is facing the service working conditions of hot and humid salt environment. Therefore, in the working process, the engine centrifugal impeller not only has to bear the centrifugal load and the bending vibration load caused by various reasons, but also may occur thermal salt corrosion fatigue under the combined action of high temperature, salt spray environment and mechanical load, and is more likely to cause blade fracture. The broken fragments will hit other components at high speed, causing greater damage to the engine. When the aircraft performs tasks at high altitude, the engine may fail, resulting in accidents, personnel casualties and property losses.

[0003] At present, the traditional thermal salt corrosion fatigue test mainly aims at low cycle load. The entire sample is completely wrapped by a heating furnace, and holes are opened at the upper and lower ends to fix the sample and apply axial load. Therefore, the heating and corrosion environment control equipment has a large size, and it is not suitable to open holes to apply transverse load in order to ensure the heat preservation effect of the heating furnace. Therefore, it is not conducive to carry out high-low cycle combined fatigue test in high-temperature hot salt corrosion environment.

[0004] Therefore, we need to propose a tensile-bending combined fatigue test device and method with simple structure, which can locally heat the simulation sample test section and apply tensile-bending load to accurately reflect the real stress, temperature and corrosion environment of the engine. Through corrosion fatigue risk point analysis of the engine centrifugal impeller, a simulation test piece is designed, and the strain of the engine centrifugal impeller simulation piece is analyzed through high-temperature corrosion environment tensile-bending combined fatigue test to simulate the working state of the real blade and obtain the corrosion fatigue life of the working state. SUMMARY

[0005] The application aims to provide an engine centrifugal impeller simulation sample high-temperature corrosion environment tension-bending compound fatigue test device and method, which can simulate the main load, such as low-frequency centrifugal load, high-frequency bending vibration load, high temperature and marine hot salt corrosion environment, which the real blade is subjected to in the working process. The axial tension load is applied to the simulation sample to simulate the centrifugal load in the rotation, the eddy current exciter is used to simulate the bending vibration load perpendicular to the axial direction, the electric heating furnace is used to simulate the temperature environment of the blade in the working process, and the salt film concentration accumulated in the marine environment is simulated by quantitatively spraying the salt mist on the sample test section, so that the high-low frequency compound fatigue test of the engine centrifugal impeller simulation sample under the high-temperature hot salt corrosion environment can be smoothly carried out, and a technical basis and safety guarantee for the safe and reliable work of the turboshaft engine in the marine salt mist environment is provided.

[0006] The technical scheme of the application is:

[0007] An engine centrifugal impeller simulation sample high-temperature corrosion environment tension-bending compound fatigue test device, comprising a simulation sample 6, characterized in that: further comprising an axial load system, a transverse vibration system, a temperature control system and a measurement system.

[0008] The simulation sample 6 is designed according to the local position of the centrifugal impeller, the salt film is sprayed on the test part, and the working temperature is applied to simulate the marine salt mist corrosion and high-temperature environment.

[0009] The axial load system comprises a fatigue machine 11 and a clamping system; the clamping system comprises an upper clamp 22, a bendable device 7 and a lower clamp 21; the bendable device 7 comprises a connecting rod 73, an excitation plate 74 and a pressing plate 75; the excitation plate 74 and the pressing plate 75 are provided with grooves;

[0010] The transverse vibration system comprises a signal generator 31, a power amplifier 32 and an eddy current exciter 33;

[0011] The temperature control system is a small local heating furnace 42 with a control system;

[0012] The measurement system comprises a displacement sensor 51, a digital frequency meter 52, an oscilloscope 53, a computer 57, a dynamic data acquisition and analysis system 56, a dynamic strain meter 55 and a strain gauge 54;

[0013] The simulation sample 6 is placed in the grooves of the excitation plate 74 and the pressing plate 75 and fixed by a pin;

[0014] The upper clamp 22 is connected with the upper end of the fatigue machine 11, and the lower clamp 21 is connected with the lower end of the fatigue machine 11; one end of the connecting rod 73 is connected with the upper clamp 22 through a pin, and the other end is connected with the excitation plate 74 through a pin; the excitation plate 74 and the pressing plate 75 are connected through bolts.

[0015] The signal generator 31, the power amplifier 32 and the eddy current exciter 33 are connected by wires, placed on a support frame fixed on the fatigue machine 11, and the eddy current exciter 33 is located on the side of the excitation plate 74;

[0016] The heating furnace 42 is placed on a support frame fixed on the fatigue machine 11, located below the eddy current exciter 33;

[0017] The strain gauge 54 is pasted on the simulation sample 6, located in the middle area between the heating furnace 42 and the eddy current exciter 33, and is connected by wires between the dynamic strain meter 55, the dynamic data acquisition and analysis system 56 and the computer 57; the displacement sensor 51 is located on the side of the simulation sample 6, and is connected by wires between the digital frequency meter 52 and the oscilloscope 53.

[0018] Further, the simulation sample 6 uses a local surface for quantitative salt spray coating / deposition, simulating the accumulated salt film concentration in the marine salt spray environment.

[0019] Further, the signal generator 31 generates a sinusoidal signal, the power amplifier 32 amplifies the sinusoidal signal, and the eddy current exciter 33 receives the amplified current to generate a periodically varying electromagnetic force.

[0020] Further, the power amplifier 32 has an ammeter, and the working state of the power amplifier 32 is monitored by observing the current size, and the amplitude value of the excitation point is adjusted by adjusting the current size, to provide accurate high-frequency vibration load.

[0021] Further, the displacement sensor 51 converts the detected displacement variable into an electrical signal and transmits the electrical signal to the digital frequency meter 52; the digital frequency meter 52 displays the frequency value in digital form; the oscilloscope 53 is used to display the stabilized waveform; the dynamic strain meter 55 measures the strain of the simulation sample during the test by connecting the strain gauge 54; the dynamic data acquisition and analysis system 56 is used to control the dynamic strain meter 55 and collect strain values; the computer 57 stores and processes the collected strain values.

[0022] A high-temperature corrosion environment tension-bending combined fatigue test method for an engine centrifugal impeller simulation sample, characterized in that it comprises the following steps:

[0023] Step 1: design and process the simulation sample 6;

[0024] Step 2: assemble the test device and fix the simulation sample 6;

[0025] Step 3: Determine the load excitation level, and conduct formal composite fatigue tests at different load excitation levels to obtain test data at different load excitation levels;

[0026] Step 4: Repeat the above steps to test other simulation samples 6.

[0027] Further, the step 1 comprises:

[0028] Step 1-1: Design the simulation sample 6 according to the local position and stress state of the centrifugal impeller, and then perform finite element analysis on the simulation sample 6 to calculate whether the stress distribution of the simulation sample 6 in the test area is consistent with the real blade, and finally determine the shape of the sample through multiple calculations;

[0029] Step 1-2: According to the designed shape, spray a certain concentration of salt spray on the local surface of the simulation sample 6:

[0030] First, the test piece is ultrasonically cleaned with distilled water and then dried, then the test piece is sprayed with NaCl droplet particles by a spray pen, the spraying speed is adjusted by pressure, and finally the salt content on the surface of the test sample is controlled by weighing method to reach the preset value, after the salt spray is completely dried, the test is started.

[0031] Further, the step 2 comprises:

[0032] Step 2-1: Install the upper clamp 22, the connecting rod 73 and the excitation plate 74 in sequence by the pin connection method;

[0033] Step 2-2: Place the eddy current exciter 33 on the support frame to ensure that the simulation sample 6 can pass through the middle of the support frame;

[0034] Step 2-3: Place the heating furnace 42 on the support frame and keep it fixed to determine that the test part of the simulation sample 6 can be placed in the furnace cavity of the heating furnace 42;

[0035] Step 2-4: Obtain the modal shape, harmonic response and vibration stress distribution of the test simulation piece through mutual verification of numerical simulation and test, determine the pasting position of the strain gauge 54 according to the vibration stress distribution, paste the strain gauge 54 on the corresponding area of the simulation sample 6, and connect the strain gauge 54 with the dynamic strain meter 55 and the dynamic data acquisition and analysis system 56 through wires, transmit the obtained signals to the dynamic data acquisition and analysis system 56, so as to obtain the strain value;

[0036] Step 2-5: Select a fixed point on the simulation sample 6 as the positioning point of the displacement sensor 51, and real-time detect the transverse vibration displacement of the simulation sample 6, and establish the response relationship between the transverse displacement and the transverse vibration strain value;

[0037] Step 2-6: Place the simulation sample 6 in the groove between the excitation plate 74 and the pressing plate 75, use bolts to cooperate the excitation plate 74 and the pressing plate 75, insert the pin in the pin hole of the excitation plate 74 and the pressing plate 75, and fix the sample.

[0038] Further, the step 3 comprises:

[0039] Step 3-1: Turn on the switch of the second controller 41, set the temperature of the heating furnace 42, and heat the simulation sample 6.

[0040] Step 3-2: Load axial load:

[0041] When the temperature of the simulation sample 6 reaches the predetermined working temperature, start the fatigue machine 11, set the load value through the first controller 12, apply axial load to the simulation sample 6, and monitor the axial load in real time through the first controller 12, and then load the bending vibration load perpendicular to the axial direction when the load is stable.

[0042] Step 3-3: Load bending vibration load:

[0043] Start the signal generator 31, select a sine waveform, input the loading frequency, adjust the knob of the power amplifier 32 to control the load size output by the eddy current exciter 33, detect the transverse vibration displacement of the simulation sample 6 in real time through the displacement sensor 51, and further detect the transverse load. If it deviates from the theoretical value, it needs to be adjusted in time through the power amplifier 32. The current and voltage of the power amplifier 32 are observed to monitor the working state in real time. If it is abnormal, stop the test in time to prevent equipment damage.

[0044] Step 3-4: Turn on the switches of the digital frequency meter 52 and the oscilloscope 53, and observe the waveform after stabilization.

[0045] Step 3-5: The test proceeds normally until the simulation sample 6 breaks.

[0046] The beneficial effects of the present application are:

[0047] 1. The present application provides a high-temperature test device and method for engine centrifugal impeller simulation sample tension-bending composite fatigue, which can provide axial tensile load to simulate the centrifugal load that the real blade receives during rotation, and can also provide bending load in the direction perpendicular to the axial direction to simulate the bending vibration load that the real blade receives. In addition, the heating furnace can also provide the temperature environment of the real blade during work for the simulation sample. At the same time, by spraying salt mist on the surface of the sample, the corrosion of the blade in the working process is simulated, and the real stress, temperature and corrosion environment of the engine are accurately reflected, so that the test can more accurately simulate the tension-bending composite fatigue of the dangerous part in the working process.

[0048] 2. The experimental system of this invention only heats the part where the test condition is applied. The scheme is simple, eliminates unnecessary heating parts, and adopts a local heating method. It only requires a small experimental device to simulate the conditions required for the experiment.

[0049] 3. In the test process of this invention, the salt spray concentration, temperature, axial force and vibration load are relatively independent systems, and any working condition can be directly modified, which facilitates the adjustment of test parameters. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the tensile-bending combined fatigue testing device of the present invention;

[0051] Figure 2 This is a schematic diagram of the simulated specimen clamp of the tensile-bending composite fatigue testing device of the present invention;

[0052] Explanation of reference numerals in the attached figures:

[0053] 11-Fatigue machine, 12-First controller, 21-Lower clamp, 22-Upper clamp, 31-Signal generator, 32-Power amplifier, 33-Eddy current vibrator, 41-Second controller, 42-Heating furnace, 51-Displacement sensor, 52-Digital frequency meter, 53-Oscilloscope, 54-Strain gauge, 55-Dynamic strain gauge, 56-Dynamic data acquisition and analysis system, 57-Computer, 6-Simulated specimen, 7-Bendable device;

[0054] 71-Threaded hole, 72-Pin hole, 73-Connecting rod, 74-Vibration plate, 75-Pressure plate. Detailed Implementation

[0055] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0056] This invention discloses a high-temperature corrosion environment tensile-bending combined fatigue testing device for a simulated engine centrifugal impeller. The device includes an axial load system, a transverse vibration system, a temperature control system, and a measurement system. The axial load system applies axial tensile-tension loads to the simulated specimen 6 via pins. The transverse vibration system provides transverse bending vibration loads to the simulated specimen 6. The temperature control system provides the test area of ​​the simulated specimen 6 with the temperature under the actual operating environment of the engine. Furthermore, to meet the requirements of the tensile-bending combined fatigue test, the simulated specimen 6 is designed based on the local load of the engine centrifugal impeller. Salt spraying / deposition is used on the specimen surface to simulate the marine salt spray corrosion environment, accurately reflecting the actual stress, temperature, and corrosion environment of the engine. This allows the test to more accurately simulate the tensile-bending combined fatigue conditions of dangerous parts during operation.

[0057] See Figure 1 ,Figure 2 The axial load system of the present application comprises a fatigue machine 11 and a clamping system, the clamping system comprising an upper clamp 22, a bendable device 7 and a lower clamp 21, the upper clamp 22 being connected with the upper end of the fatigue machine 11, the lower clamp 21 being connected with the lower end of the fatigue machine 11, the bendable device 7 comprising a connecting rod 73, a vibration plate 74 and a pressing plate 75, one end of the connecting rod 73 being connected with the upper clamp 22 through a pin, the other end of the connecting rod 73 being connected with the vibration plate 74 through a pin, the end of the vibration plate 74 not connected with the connecting rod 73 being connected with the pressing plate 75 through a bolt, the vibration plate 74 and the pressing plate 75 being provided with grooves, the simulation sample 6 being placed in the grooves of the vibration plate 74 and the pressing plate 75 and being fixed through a pin;

[0058] The transverse vibration system comprises a signal generator 31, a power amplifier 32 and an eddy current vibration exciter 33, the signal generator 31, the power amplifier 32 and the eddy current vibration exciter 33 being connected through wires and being placed on a support frame, the support frame being fixed on the fatigue machine 11, and the eddy current vibration exciter 33 being located at the side of the vibration plate 74, the signal generator 31 generating a sinusoidal signal during the test, the power amplifier 32 amplifying the sinusoidal signal, the eddy current vibration exciter 33 receiving the amplified current and further generating a periodically changing electromagnetic force, and the power amplifier 32 being provided with an ammeter, and the working state of the power amplifier 32 being monitored by observing the current size;

[0059] The temperature control system is a small local heating furnace 42 with a control system, which is placed on a support frame, the support frame being fixed on the fatigue machine 11 and being located below the eddy current vibration exciter 33;

[0060] The measurement system comprises a displacement sensor 51, a digital frequency meter 52, an oscilloscope 53, a computer 57, a dynamic data acquisition and analysis system 56, a dynamic strain meter 55 and a strain gauge 54, the displacement sensor 51 being connected with the digital frequency meter 52 and being located at the side of the simulation sample 6, the displacement sensor 51 converting the detected displacement variable into an electric signal and transmitting the electric signal to the digital frequency meter 52, the digital frequency meter 52 being connected with the oscilloscope 53 and displaying the frequency value in a digital form, the oscilloscope 53 being used for displaying the stable waveform, the strain gauge 54 being pasted on the simulation sample 6 and being located in the middle region between the heating furnace 42 and the eddy current vibration exciter 33, the dynamic strain meter 55 measuring the strain of the simulation sample 6 in the test process by connecting with the strain gauge 54, the dynamic data acquisition and analysis system 56 being used for controlling the dynamic strain meter 55 and collecting the strain value, and the computer 57 being used for storing and processing the collected strain value.

[0061] The method for testing by using the device of the present application is specifically as follows:

[0062] Step 1: design and process the simulation sample 6:

[0063] Step 1-1: According to the local position and stress state of the centrifugal impeller, a simulation sample 6 is designed, and then finite element analysis is performed to calculate whether the stress distribution of the simulation sample 6 in the test area is consistent with the real blade. After multiple calculations, the shape of the sample is finally determined;

[0064] Step 1-2: According to the designed shape, spray a certain concentration of salt mist on the local surface of the simulation sample 6: first, clean the test piece with distilled water and dry it, then use a spray pen to spray NaCl droplet particles on the test piece, adjust the spraying speed through pressure, and finally control whether the salt content on the surface of the sample reaches the preset value through weighing method. After the salt mist is completely dried, the test begins.

[0065] Step 2: Assemble the test device and fix the simulation sample 6:

[0066] Step 2-1: Install the upper clamp 22, connecting rod 73, and excitation plate 74 in sequence through pin connection;

[0067] Step 2-2: Place the eddy current exciter 33 on the support frame to ensure that the simulation sample 6 can pass through the middle;

[0068] Step 2-3: Place the heating furnace 42 on the support frame and keep it fixed to ensure that the test part of the simulation sample 6 can be placed in the furnace cavity of the heating furnace 42;

[0069] Step 2-4: Obtain the modal shape, harmonic response, and vibration stress distribution of the test simulation piece through numerical simulation and mutual verification of the test. According to the vibration stress distribution, determine the paste position of the strain gauge 54, and paste the strain gauge 54 on the corresponding area of the simulation sample 6. The strain gauge 54 is connected to the dynamic strain meter 55 and the dynamic data acquisition and analysis system 56 through wires, and the obtained signals are transmitted to the dynamic data acquisition and analysis system 56, so as to obtain the strain value;

[0070] Step 2-5: Select a fixed point on the simulation sample 6 as the positioning point of the displacement sensor 51 to detect the transverse vibration displacement of the simulation sample 6 in real time, and establish the response relationship between the transverse displacement and the transverse vibration strain value;

[0071] Step 2-6: Place the simulation sample 6 in the groove between the excitation plate 74 and the pressing plate 75, use bolts to cooperate the excitation plate 74 and the pressing plate 75, insert the pins in the pin holes of the excitation plate 74 and the pressing plate 75, and fix the sample.

[0072] Step 3: Determine the load excitation level, and perform formal composite fatigue test under different load excitation levels to obtain test data under different load excitation levels:

[0073] Step 3-1: Turn on the switch of the second controller 41 and set the temperature of the heating furnace 42 to heat the simulation sample 6;

[0074] Step 3-2: loading axial load: when the temperature of the simulation sample 6 reaches the predetermined working temperature, start the fatigue machine 11, set the value of the load to be applied by the first controller 12, apply axial load to the simulation sample 6, and monitor the axial load in real time by the first controller 12, and then load the bending vibration load perpendicular to the axial load when the load is stable;

[0075] Step 3-3: loading bending vibration load: start the signal generator 31, select a sine waveform, input the loading frequency, adjust the knob of the power amplifier 32 to control the load size output by the eddy current exciter 33, detect the transverse vibration displacement of the simulation sample 6 in real time by the displacement sensor 51, and then detect the transverse load. If it deviates from the theoretical value, it needs to be adjusted in time through the power amplifier 32. By observing the current and voltage of the power amplifier 32, the working state is monitored in real time. If it is abnormal, stop the test in time to prevent equipment damage;

[0076] Step 3-4: turn on the switches of the digital frequency meter 52 and the oscilloscope 53, and observe the waveform after stabilization;

[0077] Step 3-5: the test is carried out normally until the simulation sample 6 is broken.

[0078] Step 4: repeat the above steps to test other simulation samples 6.

[0079] Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. An engine centrifugal impeller simulation sample high-temperature corrosion environment tension-bending combined fatigue test device, comprising a simulation sample (6), characterized in that: The axial load system, the lateral vibration system, the temperature control system and the measurement system are also included; ​ The simulation sample (6) is designed according to the local position of the centrifugal impeller, the test position is sprayed with salt film and the working temperature is applied to simulate the marine salt spray corrosion and high temperature environment; The axial load system includes a fatigue machine (11) and a clamping system; the clamping system includes an upper clamp (22), a bendable device (7) and a lower clamp (21); the bendable device (7) includes a connecting rod (73), an excitation plate (74) and a pressing plate (75); the excitation plate (74) and the pressing plate (75) are provided with grooves; The lateral vibration system includes a signal generator (31), a power amplifier (32) and an eddy current exciter (33); The temperature control system is a small local heating furnace (42) with a control system; The measurement system includes a displacement sensor (51), a digital frequency meter (52), an oscilloscope (53), a computer (57), a dynamic data acquisition and analysis system (56), a dynamic strain meter (55) and a strain gauge (54); The simulation sample (6) is placed in the grooves of the excitation plate (74) and the pressing plate (75) and is fixed by a pin; The upper clamp (22) is connected with the upper end of the fatigue machine (11), the lower clamp (21) is connected with the lower end of the fatigue machine (11); one end of the connecting rod (73) is connected with the upper clamp (22) by a pin, the other end is connected with the excitation plate (74) by a pin; the end of the excitation plate (74) not connected with the connecting rod (73) is connected with the pressing plate (75) by a bolt; The signal generator (31), the power amplifier (32) and the eddy current exciter (33) are connected by wires, are placed on a support frame and are fixed on the fatigue machine (11), and the eddy current exciter (33) is located on the side of the excitation plate (74); The heating furnace (42) is placed on a support frame, is fixed on the fatigue machine (11) and is located below the eddy current exciter (33); The strain gauge (54) is pasted on the simulation sample (6), is located in the middle region between the heating furnace (42) and the eddy current exciter (33) and is connected by wires with the dynamic strain meter (55), the dynamic data acquisition and analysis system (56) and the computer (57); the displacement sensor (51) is located on the side of the simulation sample (6) and is connected by wires with the digital frequency meter (52) and the oscilloscope (53).

2. The engine centrifugal impeller simulation specimen high-temperature corrosion environment tension-bending combined fatigue test device according to claim 1, characterized in that: The simulation sample (6) adopts a local surface to quantitatively spray / deposit salt mist, simulating the accumulated salt film concentration in the marine salt mist environment.

3. The engine centrifugal impeller simulation specimen high-temperature corrosion environment tension-bending combined fatigue test device according to claim 1, characterized in that: The signal generator (31) generates a sinusoidal signal, the power amplifier (32) amplifies the sinusoidal signal, the eddy current exciter (33) receives the amplified current and further generates a periodically changing electromagnetic force.

4. The engine centrifugal impeller simulation specimen high-temperature corrosion environment tension-bending combined fatigue test device according to claim 3, characterized in that: The power amplifier (32) is provided with an ammeter, the working state of the power amplifier (32) is monitored by observing the current size, the amplitude value of the excitation point is adjusted by adjusting the current size, and accurate high-frequency vibration load is provided.

5. The engine centrifugal impeller simulation specimen high-temperature corrosion environment tension-bending combined fatigue test device according to claim 1, characterized in that: The displacement sensor (51) converts the detected displacement variable into an electrical signal and transmits the electrical signal to a digital frequency meter (52); the digital frequency meter (52) displays the frequency value in digital form; the oscilloscope (53) is used to display the stabilized waveform; the dynamic strain gauge (55) measures the strain of the analog sample during the test process through the connection of the strain gauge; the dynamic data acquisition and analysis system (56) is used to control the dynamic strain gauge (55) and collect the strain value; the computer (57) stores and processes the collected strain value.

6. The method for the high-temperature corrosion environment tensile-bending combined fatigue test of the engine centrifugal impeller simulation sample, characterized in that, It comprises the following steps: Step 1: design and process the analog sample (6); Step 2: assemble the test device and fix the analog sample (6); Step 3: determine the load excitation level, and conduct formal composite fatigue tests under different load excitation levels to obtain test data under different load excitation levels; Step 4: repeat the above steps to test other analog samples (6).

7. The method according to claim 6, wherein the method is a high-temperature corrosion environment tension-bending combined fatigue test method for an engine centrifugal impeller simulation sample. The step 1 comprises: Step 1-1: design the analog sample (6) according to the local position and stress state of the centrifugal impeller, and then perform finite element analysis on the analog sample (6) to calculate whether the stress distribution of the analog sample (6) in the test area matches the real blade, and finally determine the shape of the sample after multiple calculations; Step 1-2: according to the designed shape, spray a certain concentration of salt mist on the local surface of the analog sample (6): First, clean the test piece with distilled water and dry it, then use a spray pen to spray NaCl droplet particles on the test piece, adjust the spraying speed through pressure, and finally control whether the salt content on the surface of the sample reaches the preset value through weighing method, after the salt mist is completely dried, start the test.

8. The method according to claim 6, wherein the method is a high-temperature corrosion environment tension-bending combined fatigue test method for an engine centrifugal impeller simulation sample. The step 2 comprises: Step 2-1: install the upper clamp (22), connecting rod (73) and excitation plate (74) in sequence through pin connection; Step 2-2: place the eddy current exciter (33) on the support frame to ensure that the analog sample (6) can pass through the middle; Step 2-3: place the heating furnace (42) on the support frame and keep it fixed to determine that the test part of the analog sample (6) can be placed in the furnace cavity of the heating furnace (42); Step 2-4: obtain the modal shape, harmonic response and vibration stress distribution of the test analog piece through mutual verification of numerical simulation and test, determine the paste position of the strain gauge (54) according to the vibration stress distribution, paste the strain gauge (54) on the corresponding area of the analog sample (6), and connect the strain gauge (54) with the dynamic strain gauge (55) and the dynamic data acquisition and analysis system (56) through wires to transmit the obtained signals to the dynamic data acquisition and analysis system (56), thereby obtaining the strain value; Step 2-5: select a fixed point on the analog sample (6) as the positioning point of the displacement sensor (51), real-time detect the transverse vibration displacement of the analog sample (6), and establish the response relationship between the transverse displacement and the transverse vibration strain value; Step 2-6: Place the simulation sample (6) in the groove between the excitation plate (74) and the pressing plate (75), connect the excitation plate (74) and the pressing plate (75) with bolts, insert the pins into the pin holes of the excitation plate (74) and the pressing plate (75), and fix the sample.

9. The method of claim 6, wherein the method is a high-temperature corrosion environment tension-bending combined fatigue test method for an engine centrifugal impeller simulation sample. The step 3 comprises: Step 3-1: Turn on the switch of the second controller (41) and set the temperature of the heating furnace (42), and heat the simulation sample (6); Step 3-2: Load the axial load: When the temperature of the simulation sample (6) reaches the predetermined working temperature, start the fatigue machine (11), set the load value through the first controller (12), apply the axial load to the simulation sample (6), and monitor the axial load in real time through the first controller (12), and then load the bending vibration load perpendicular to the axial load when the load is stable; Step 3-3: Load the bending vibration load: Start the signal generator (31), select the sine waveform, input the load frequency, adjust the knob of the power amplifier (32), control the output load size of the eddy current exciter (33), detect the transverse vibration displacement of the simulation sample (6) in real time through the displacement sensor (51), and further detect the transverse load, if deviating from the theoretical value, need to adjust in time through the power amplifier (32), observe the current and voltage of the power amplifier (32) to monitor the working state in real time, if abnormal, stop the test in time to prevent equipment damage; Step 3-4: Turn on the switches of the digital frequency meter (52) and the oscilloscope (53), and observe the waveform after stabilization; Step 3-5: The test is carried out normally until the simulation sample (6) is broken.

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