A method for determining accelerated test parameters for high-cycle fatigue examination of a blade

Abstract

The application provides a method for determining accelerated test parameters for high-cycle fatigue test of blades, comprising: performing vibration characteristic simulation analysis and whole machine dynamic stress measurement test on components with rotor blades of an aero-engine, obtaining resonance rotating speeds, frequencies and vibration modes of rotor blades of each component in a working rotating speed range; determining simulation life limiting values and actual measurement life limiting values of each component respectively, and simultaneously, correcting the resonance frequencies of the blades to obtain frequency dispersions of rotor blades of each component; drawing all resonance rotating speed points to obtain resonance rotating speed spectra of rotor blades of each component; drawing the residence time of rotor blades of each component at a certain rotating speed on the resonance rotating speed spectrum, taking the longest residence time as the test time at the rotating speed, and then obtaining a mixed frequency test state of the engine; formulating high-cycle fatigue test parameters and carrying out test verification, if no blade is damaged, the parameter formulation is reasonable; if not, the test parameters are determined again.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aero-engine test, and particularly relates to a method for determining accelerated test parameters for high-cycle fatigue test of blades. BACKGROUND

[0002] In order to fully test the safety and reliability of an aero-engine and ensure that a key component, especially a blade, will not be damaged due to high-cycle fatigue failure within a design life, high-cycle fatigue test of the aero-engine is required.

[0003] However, the time for fully testing the high-cycle fatigue of the blade is too long. For example, the high-cycle fatigue cycle of a titanium alloy blade can reach 10 8 If the test is completely performed on the whole machine, the development cycle will be greatly prolonged and the development cost will be increased.

[0004] At present, the common method is to use accelerated test, that is, to increase the test load or artificially superimpose the vibration cycle of the blade to make the blade reach the required cycle in a short time. However, there is no effective method to test all the blades of the engine, especially the fan and turbine blades, which have a large frequency difference and require different test times. The test time of the fan can be 4 times that of the turbine blade. On the other hand, since there are many vibration orders of the blade, each resonance mode needs to be fully considered to ensure that the aero-engine blade will not be damaged by high-cycle fatigue within the design life.

[0005] Therefore, it is necessary to design a reasonable test parameter to meet the high-cycle fatigue test requirements of the blades of the fan, compressor and turbine. SUMMARY

[0006] The purpose of the present application is to provide a method for determining accelerated test parameters for high-cycle fatigue test of blades to solve or alleviate at least one problem in the background art.

[0007] The technical solution of the present application is a method for determining accelerated test parameters for high-cycle fatigue test of blades, which comprises the following steps:

[0008] Performing vibration characteristic simulation analysis on the components of the aero-engine having rotor blades to obtain the resonance speed, frequency and mode of each component rotor blade within the working speed range, and simultaneously performing whole-machine dynamic stress measurement test to obtain the actually measured resonance speed, frequency and mode of each component rotor blade within the whole speed range;

[0009] According to the vibration characteristic simulation analysis results and the whole-machine dynamic stress measurement results, the simulation life limiting value and the actually measured life limiting value of each component are determined respectively, and the blade resonance frequency is corrected to obtain the frequency after correction of the blade dispersion, and the frequency dispersion of each component rotor blade is obtained according to the frequency.

[0010] Based on the measured results, all resonance speed points are plotted on a single graph to obtain the resonance speed spectrum of the rotor blades of each component.

[0011] The residence time of each component rotor blade at a certain speed is plotted on the resonant speed spectrum, and the longest residence time is taken as the test time at that speed, thereby obtaining the engine test mixing state.

[0012] Based on the mixing state, high-cycle fatigue test parameters are formulated, including the test speed and residence time. Based on the high-cycle fatigue test parameters, accelerated testing of the whole machine is carried out for high-cycle fatigue assessment, and surface crack detection of blades is conducted. If, after the test, no high-cycle fatigue failure occurs in the rotor blades of any component, then the high-cycle fatigue test parameters are reasonable and the purpose of high-cycle fatigue assessment is achieved. If there are blades that do not meet the design requirements, analysis work is carried out and the test plan is redefined.

[0013] Furthermore, the component with rotor blades includes a fan, a compressor, a low-pressure turbine, and a high-pressure turbine.

[0014] Furthermore, the process for determining the simulation lifetime limit value includes:

[0015] The high-cycle fatigue life requirement (N) for blade materials is obtained through relevant standards. f ;

[0016] The high-cycle fatigue life requirement N for blade materials f Divide by the frequency F of each simulated resonant rotational speed C Obtain the simulated resonant rotational speed W C The dwell time t C =N f / F C .

[0017] Furthermore, the process for determining the measured lifespan limit value includes:

[0018] The high-cycle fatigue life requirement (N) for blade materials is obtained through relevant standards. f ;

[0019] The high-cycle fatigue life requirement N for blade materials f Divide by the frequency F of each measured resonant rotational speed R Obtain the simulated resonant rotational speed W R The dwell time t C =N f / F R .

[0020] Furthermore, the process of correcting the blade resonance frequency to obtain the corrected frequency includes:

[0021] According to the ratio of the rotor blade measured frequency and the average value of the measured frequency, multiplied by the theoretical resonance frequency given by the blade vibration characteristic analysis, the frequency of the blade dispersion correction is obtained, that is:

[0022] F 修正 = F 理论 × (F 目标 / F 平均 )

[0023] In the formula, F 修正 refers to the frequency after the blade dispersion correction, F 理论 refers to the blade resonance frequency given by the vibration characteristic simulation analysis, F 目标 refers to the target value of the blade frequency dispersion correction, and F 平均 refers to the average value of the measured blade frequency.

[0024] Further, the calculation method of the frequency dispersion S is:

[0025] S = (F 修正 -F 理论 ) / F 理论 .

[0026] Further, when the difference between the measured frequency and the nominal frequency is greater than a predetermined value, the resonance speed is drawn as a resonance speed band when drawing the resonance speed spectrum of the rotor blade.

[0027] Further, the resonance speed band W x (1 ± S), wherein W is the resonance speed, and S is the frequency dispersion.

[0028] The accelerated measured parameter determination method provided in the application obtains the key blade limiting the service life of the engine through numerical simulation analysis of the blade vibration mode and frequency of each component, the whole machine dynamic frequency and the resonance speed, and adopts the mixing method, so that all the blades can reach the purpose of fully examining the high-cycle fatigue life after the accelerated test run, thereby saving the test cost and period. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions provided in the application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the application.

[0030] Figure 1 The flow chart of the accelerated test parameter determination method of the application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be described in more detail below with reference to the drawings in the embodiments of the application.

[0032] The purpose of this application is to design a method for determining the high-cycle fatigue test parameters of blades that is applicable in engineering. This method can determine the high-cycle fatigue test parameters of blades, thereby accelerating the test, saving the R&D cycle and R&D costs.

[0033] like Figure 1 As shown, the method for determining accelerated test parameters for high-cycle fatigue testing of blades provided in this application includes the following steps:

[0034] S1. Vibration characteristic simulation analysis and engine dynamic stress measurement

[0035] Vibration characteristic simulation analysis is performed on components of aero-engines with rotor blades—including fans, compressors, high-pressure turbines, and low-pressure turbines—to obtain the resonant speeds, frequencies, and mode shapes of the rotor blades within the operating speed range, and Campbell diagrams are plotted.

[0036] At the same time, whole-machine dynamic stress measurement tests were carried out to obtain the measured resonant speed, frequency and mode shape of the rotor blades of each component across the entire speed range.

[0037] S2. Determination of constraint values ​​based on simulation, actual measurement, and dispersion.

[0038] Because the resonant speed, frequency, and mode shape of the rotor blades in each component are completely different, and the high-cycle fatigue life N f The requirements also differ. In order to fully evaluate the rotor blades of each component, this application combines the simulation, actual measurement and dispersion of each component to jointly determine the life-limiting parts.

[0039] S21. Determination of Simulation Limits

[0040] Based on the vibration characteristic simulation analysis results, the life limitation state of each component is determined. This process includes: meeting the high-cycle fatigue life requirements N for blade materials in the standard. f Divide by the frequency F of each simulated resonant rotational speed C The simulated resonant rotational speed W was obtained. C The dwell time t C =N f / F C .

[0041] S22. Determination of measured limit values

[0042] Based on the overall dynamic stress measurement results, the life limit status of each component is determined. This process includes: meeting the high-cycle fatigue life requirements N for materials in the standard. f Divide by the frequency F of each measured resonant rotational speed R The measured resonant rotational speed W was obtained. R The dwell time t R =Nf / F R .

[0043] S23, determine the frequency dispersion of the rotor blade.

[0044] Since the measured frequency of the rotor blade of the whole machine dynamic stress measurement and the nominal frequency of the rotor blade of the vibration characteristic simulation analysis have a certain gap, the frequency dispersion S is introduced in the application.

[0045] Wherein, the ratio of the measured frequency of the rotor blade to the average value of the measured frequency multiplied by the theoretical resonance frequency given by the blade vibration characteristic analysis is the frequency of the blade dispersion corrected, that is:

[0046] F 修正 = F 理论 ×(F 目标 / F 平均 )

[0047] In the formula, F 修正 refers to the frequency after the blade dispersion correction, F 理论 refers to the blade resonance frequency given by the vibration characteristic simulation analysis, F 目标 refers to the target value of the blade frequency dispersion correction, and F 平均 refers to the average value of the measured frequency of the blade.

[0048] The frequency dispersion S = (F 修正 -F 理论 ) / F 理论

[0049] The frequency dispersion of the rotor blade of each component (fan, high-pressure compressor, high-pressure turbine, low-pressure turbine) is represented as S FAN , S HPC , S HPT , S LPT .

[0050] S3, draw the resonance speed spectrum of the rotor blade of each component

[0051] Based on the measured results, all resonance speed points are plotted on a graph, the horizontal coordinate is the speed, the vertical coordinate is the frequency, and each excitation factor is marked. Among them, the measured frequency and the nominal frequency have a large gap, and the frequency dispersion is considered, and the resonance speed is plotted as a speed band.

[0052] For example, a certain resonance speed is W, and the resonance frequency is F, then the resonance speed band is W×(1±S), and in the actual test process, the purpose of considering the resonance frequency F can be achieved within the speed band.

[0053] S4, engine state mixing

[0054] The resonance rotating speed band and the residence rotating speed of the rotor blades of the four components, i.e., the fan, the compressor, the high-pressure turbine and the low-pressure turbine, can be determined by the above steps, and there are a large number of resonance examination rotating speeds to be examined. All the resonance examination rotating speeds are sorted, and the residence time of the rotor blades of each component at a certain rotating speed is plotted on a graph, i.e., there are four different residence times at each rotating speed, and the examination time at the rotating speed is taken as the residence time with the longest residence time, and then the engine examination mixed frequency state is obtained.

[0055] S5, high-cycle fatigue test parameter determination

[0056] According to the mixed frequency state generated in step 4, the high-cycle fatigue test parameters are formulated, mainly including the examination rotating speed and the residence time.

[0057] The whole-machine high-cycle fatigue examination acceleration test verification is carried out, the whole-machine test is continuously carried out under the test scheme formulated in step 5, and the blade surface crack detection is carried out regularly. If all the tests are completed and no high-cycle fatigue damage occurs in each blade, it is proved that the test parameter formulation is reasonable, and the purpose of high-cycle fatigue examination is achieved. If there are blades that do not meet the design requirements, analysis work is carried out, and the test scheme is re-determined.

[0058] The acceleration test parameter determination method provided in the application obtains the key blades that limit the service life of the engine by numerically simulating and analyzing the vibration mode and frequency of each component blade, the whole-machine dynamic test frequency and the resonance rotating speed, and uses the mixed frequency method, so that all the blades can reach the purpose of fully examining the high-cycle fatigue life after the acceleration test, and the test cost and period are saved.

[0059] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. Any changes or replacements within the technical range disclosed in the application can be easily thought by those skilled in the art, and should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A method for determining the accelerated test parameters for high cycle fatigue test of a blade, characterized in that, The method comprises: vibration characteristic simulation analysis is carried out on the components with rotor blades of the aero-engine, resonance rotating speeds, frequencies and vibration modes of the rotor blades of each component in a working rotating speed range are obtained, meanwhile, whole-machine dynamic stress measurement test is carried out, resonance rotating speeds, frequencies and vibration modes of the rotor blades of each component in a full rotating speed range are obtained; according to the vibration characteristic simulation analysis results and the whole-machine dynamic stress measurement results, simulation life limiting values and measured life limiting values of each component are determined respectively, meanwhile, the blade resonance frequency is corrected to obtain the frequency after correction of the blade dispersion, and the frequency dispersion of the rotor blades of each component is obtained according to the frequency; With the measured results as the benchmark, the rotor blade resonance speed spectrum of each component is obtained by plotting all resonance speed points on a graph, the horizontal coordinate is the speed, the vertical coordinate is the frequency, and each excitation factor is identified, wherein when the difference between the measured frequency and the nominal frequency of the rotor blade obtained by the vibration simulation analysis is greater than a predetermined value, the resonance speed is plotted as a resonance speed band, the resonance speed band is W x (1±S), wherein W is the resonance speed, S is the frequency dispersion, the frequency dispersion S = (F 修正 -F 理论 ) / F 理论 , F 修正 refers to the frequency after the blade dispersion is corrected, F 理论 refers to the theoretical resonance frequency of the blade given by the vibration characteristic simulation analysis, wherein the frequency after the blade dispersion is corrected is obtained by multiplying the ratio of the target value of the measured frequency of the rotor blade to the average value of the measured frequency by the theoretical resonance frequency of the blade given by the vibration characteristic simulation analysis, that is, F 修正 =F 理论 x (F 目标 / F 平均 ), F 目标 refers to the target value of the measured frequency of the blade, F 平均 refers to the average value of the measured frequency of the blade; all the examined resonance rotating speeds are sorted, the residence time of the rotor blades of each component at a certain rotating speed is drawn on a resonance rotating speed spectrum, the longest residence time is taken as the examination time at the rotating speed, and then the engine examination mixed frequency state is obtained; high-cycle fatigue test parameters are formulated according to the mixed frequency state, including the examined resonance rotating speed and the residence time, whole-machine high-cycle fatigue examination acceleration test verification is carried out according to the high-cycle fatigue test parameters, blade surface crack detection is carried out, if no high-cycle fatigue damage occurs to the rotor blades of each component after the test, the high-cycle fatigue test parameters are reasonable, and the purpose of high-cycle fatigue examination is achieved; if there are blades that do not meet the design requirements, analysis work is carried out, and the test scheme is re-determined.

2. The method for determining the accelerated test parameters for high cycle fatigue test of blade as claimed in claim 1, wherein, The components with rotor blades include a fan, a compressor, a low-pressure turbine and a high-pressure turbine.

3. The method for determining the accelerated test parameters for high cycle fatigue test of blade as claimed in claim 2, wherein, The simulation life limiting value determination process comprises: Obtain the high cycle fatigue life requirement N of the blade material through the relevant standard f ; N f F divided by the frequency of each simulated resonance speed C Obtaining simulated resonance speeds W C Residence time t C = N f / F C .

4. The method for determining the accelerated test parameters for high cycle fatigue test of blade as claimed in claim 2, wherein, The measured life limiting value determination process comprises: Obtain the high cycle fatigue life requirement N of the blade material through the relevant standard f ; N f F R W R t C N f F R .

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