Method for determining intermediate state holding load rotating speed in aeroengine acceleration task test spectrum

Abstract

The invention relates to the technical field of aero-engine load spectrums, and particularly discloses a method for determining an intermediate state holding load rotating speed in an aero-engine acceleration task test run spectrum. The method comprises the following steps: performing filtering processing on an actually measured temperature spectrum and a rotating speed spectrum of an aero-engine comprehensive mission spectrum test, applying the processed temperature spectrum and rotating speed spectrum to a high-pressure turbine disc of an aero-engine key part to compile a stress spectrum and a temperature spectrum of a dangerous point, performing a material high-temperature creep test, and calculating a material failure mode; and dividing the failure mode consistency interval of the variable-temperature variable-load creep load, and finally determining the maximum state holding load rotating speed in the test run spectrum of the acceleration task of the aero-engine. According to the method, the test run spectrum holding load section with the same failure mode can be converted into the holding load section in the large state, the holding load rotating speed in the intermediate state in the aero-engine acceleration task test run spectrum is determined on the premise of guaranteeing the consistency of the failure modes, and the acceleration task test run spectrum can be compiled conveniently.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine load spectrum, and particularly relates to a method for determining intermediate state constant speed in aero-engine acceleration task test spectrum. BACKGROUND

[0002] With the development of aviation technology, the service life of aero-engines is continuously extended, and the service life of current civil aero-engines is as long as ten thousand hours. The traditional full-life test method cannot meet the test requirements, and it will take months or even years to perform a full-life test, which has the disadvantages of high cost and long cycle. Therefore, an acceleration spectrum must be prepared on the basis of the full-life test spectrum.

[0003] Since the hot end components serve in high temperature and high pressure load conditions for a long time, they are one of the key examination objects of the acceleration task test, and one of the core difficulties of the acceleration task test is how to realize the equivalent acceleration of the load to determine the final acceleration task test spectrum. The failure modes of the hot end components of the engine under different constant speeds are inconsistent, so it is necessary to ensure that the creep load is accelerated equivalently under the premise of consistent failure modes to shorten the test time. However, the current acceleration task test spectrum preparation method is to convert the low power state to the maximum power state, and does not consider the consistent failure mode principle to determine the intermediate state constant speed in the acceleration spectrum.

[0004] Therefore, the present application designs a method for determining the intermediate state constant speed in the aero-engine acceleration task test spectrum to solve the above problems. SUMMARY

[0005] The purpose of the present application is to solve the problem in the prior art that the acceleration task test spectrum preparation method does not consider the consistent failure mode principle to determine the intermediate state constant speed in the acceleration spectrum, which causes errors in the obtained test spectrum data, and to provide a method for determining the intermediate state constant speed in the aero-engine acceleration task test spectrum, which considers the failure modes of the hot end components of the aero-engine under different constant speeds, facilitates the determination of the intermediate state constant speed in the aero-engine acceleration task test spectrum, and can more accurately and simply prepare the acceleration task test spectrum.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A method for determining the intermediate state constant speed in the aero-engine acceleration task test spectrum, characterized in that it comprises the following steps:

[0008] Step 1, normalizing the measured temperature spectrum and the speed spectrum of the comprehensive task spectrum test, and applying the normalized measured temperature spectrum and the speed spectrum to the key components of the aero-engine to prepare the stress spectrum and the temperature spectrum of the dangerous points of the high-pressure turbine disc;

[0009] Step 2, obtain the corresponding creep rupture time, rupture strain and minimum creep rate under different stress-temperature combinations through high-temperature creep test of the material;

[0010] Step 3, obtain the creep damage tolerance factor under the corresponding stress-temperature combination based on the rupture time, minimum creep rate and rupture strain;

[0011] Step 4, calculate the creep damage tolerance factor value corresponding to each level of creep load based on the creep damage tolerance factor, and divide the failure mode consistency interval of different stress temperatures;

[0012] Step 5, analyze the damage tolerance factor to determine the maximum creep load state in the failure mode consistency interval, and finally determine the intermediate maximum state load speed in the acceleration mission test run-up spectrum of the aero-engine.

[0013] Further, in step 1, the normalization processing of the measured temperature spectrum and speed spectrum of the comprehensive mission spectrum test refers to deleting small cycles and disturbance signals affecting damage calculation while retaining the loading and unloading paths of the measured load spectrum.

[0014] Further, in step 2, the creep rupture time, rupture strain and minimum creep rate under different stress-temperature combinations (σ i ,T i ) are obtained through high-temperature creep test of the material:

[0015] The high-temperature creep test of the material is carried out on a creep testing machine, a certain number of creep tests under different stress-temperature combinations (σ i ,T i ) are carried out, the creep deformation is measured using an extensometer, and it is recorded once every fixed time interval until the material creeps and ruptures, thereby obtaining the creep rupture time, rupture strain and minimum creep rate.

[0016] Further, in step 3, the process of establishing the rupture time, minimum creep rate and rupture strain to obtain the creep damage tolerance factor under the corresponding stress-temperature combination is as follows:

[0017] Based on the obtained creep rupture time, rupture strain and minimum creep rate, the creep damage tolerance factor solving expression is established:

[0018] λ=ε f / (ε m ×t f )

[0019] In the formula, λ represents the creep damage tolerance factor, ε f represents the rupture strain, ε m represents the minimum creep rate, and t f represents the creep rupture time.

[0020] Based on the creep damage tolerance factor expression, the corresponding stress temperature combination (σ i ,T i ) under the creep damage tolerance factor is obtained.

[0021] Further, in step 4, based on the creep damage tolerance factor, the creep damage tolerance factor value corresponding to each level of creep load is calculated, and the failure mode consistency interval of different stress temperatures is divided as follows:

[0022] The stress temperature combination (σ i ,T i ) creep load equivalent acceleration to the maximum creep state in the consistent damage interval is completed, and the failure mode consistency interval of different stress temperature combinations (σ i ,T i ) is completed:

[0023] When 1<λ<2.5, the failure mode is grain boundary cavity, when 2.5<λ<5, the failure mode is necking, and when λ>5, the failure mode is mainly microstructure instability of precipitate coarsening.

[0024] Further, in step 5, the intermediate maximum state load holding speed in the aero-engine acceleration task test run spectrum is finally determined as the intermediate state load holding speed in the aero-engine acceleration task test run spectrum.

[0025] Compared with the prior art, the beneficial effects of the present application are: the present application only needs to perform normalization processing on the measured spectrum and apply it to the aero-engine hot end component to compile a dangerous point temperature spectrum and a stress spectrum; only high temperature creep test is needed to obtain the creep fracture time, fracture strain and minimum creep rate under the corresponding stress temperature, the required parameters are less, the test is simple, and the cost is low;

[0026] The present application considers the failure mode consistency principle, which can ensure the consistency of the failure mode of the load before and after acceleration; only the maximum creep load state load holding speed in the failure mode consistency interval is needed to determine the intermediate state load holding speed in the aero-engine acceleration task test run spectrum, which can more accurately and simply compile the acceleration task test run spectrum. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The flow chart of the method for determining the intermediate state load holding speed in the aero-engine acceleration task test run spectrum of the embodiment of the present application is shown in the figure;

[0028] Figure 2 The measured speed temperature spectrum graph of the engine comprehensive task spectrum in the embodiment of the present application is shown in the figure;

[0029] Figure 3 is a normalized temperature spectrum in the embodiment of the present application;

[0030] Figure 4 is a normalized temperature spectrum in the embodiment of the present application;

[0031] Figure 5 is a temperature stress spectrum prepared in the embodiment of the present application;

[0032] Figure 6 is a schematic diagram of the intermediate maximum state constant speed in the aero-engine acceleration task test spectrum in the embodiment of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application.

[0034] The embodiment first describes the principle of the method for determining the intermediate state constant speed in the aero-engine acceleration task test spectrum, as shown in the figure, the method includes the following steps: Figure 1

[0035] Step 1, normalizing the measured temperature spectrum and the speed spectrum of the comprehensive task spectrum test, and applying the normalized measured temperature spectrum and the speed spectrum to the aero-engine key piece high-pressure turbine disc to prepare the stress spectrum and the temperature spectrum of the dangerous point;

[0036] The normalizing of the measured temperature spectrum and the speed spectrum of the comprehensive task spectrum test refers to deleting the small cycles and the disturbance signals affecting damage calculation while retaining the loading and unloading paths of the measured load spectrum.

[0037] The normalized speed spectrum and the temperature spectrum are applied to the high-pressure turbine disc to calculate the temperature spectrum and the stress spectrum of the dangerous point through thermal-solid coupling analysis by using the finite element software.

[0038] Step 2, obtaining the corresponding creep rupture time, rupture strain and minimum creep rate under different stress temperature combinations (σ i ,T i ) through the high-temperature creep test of the material;

[0039] The high-temperature creep test of the material is carried out on a creep testing machine, a certain number of creep tests under different stress temperature combinations (σ i ,T i ) are carried out, the creep deformation is measured by using an extensometer, and is recorded once every fixed time interval (such as 10 seconds) until the material creeps and ruptures, so as to obtain the creep rupture time t f , the rupture strain ε f and the minimum creep rate ε m .​

[0040] Step 3, based on the rupture time t f , the minimum creep rate ε m and the rupture strain ε f , the creep damage tolerance factor under the corresponding stress temperature combination is obtained;

[0041] The rupture time t f , the minimum creep rate ε m and the rupture strain ε f are established, and the process of obtaining the creep damage tolerance factor under the corresponding stress temperature combination is as follows:

[0042] Based on the obtained creep rupture time t f , the rupture strain ε f , the minimum creep rate ε m and the established creep damage tolerance factor solving expression:

[0043] λ = ε f / (ε m × t f )

[0044] In the formula, λ represents the creep damage tolerance factor, ε f represents the rupture strain, ε m represents the minimum creep rate, and t f represents the creep rupture time.

[0045] Based on the creep damage tolerance factor solving expression, the creep damage tolerance factor under the corresponding stress temperature combination (σ i , T i ) is obtained.

[0046] Step 4, based on the creep damage tolerance factor, the creep damage tolerance factor value corresponding to each level of creep load is calculated, and the consistency interval division of the failure mode under different stress temperatures is performed, and the process is as follows:

[0047] The stress temperature combination (σ i , T i ) creep load equivalent to the maximum creep state in the consistent damage interval when the creep damage tolerance factor is respectively between 1<λ<2.5, 2.5<λ<5 and λ>5 is completed, and the consistency interval division of the failure mode under different stress temperature combinations (σ i , T i ) is completed:

[0048] When 1<λ<2.5, the failure mode is grain boundary cavity, when 2.5<λ<5, the failure mode is necking, and when λ>5, the failure mode is mainly microstructure instability of precipitate coarsening.

[0049] Step 5, analyzing the damage tolerance factor, determining the maximum creep load state in the failure mode consistency interval, and finally determining the intermediate maximum state load holding speed in the aero-engine acceleration task test run spectrum. The intermediate maximum state load holding speed in the aero-engine acceleration task test run spectrum is finally determined as the intermediate state load holding speed in the aero-engine acceleration task test run spectrum.

[0050] The above method for determining the intermediate state load holding speed in the aero-engine acceleration task test run spectrum will be further described in combination with example data.

[0051] The method for determining the intermediate state load holding speed in the aero-engine acceleration task test run spectrum is applied to the determination of the intermediate load holding speed in the acceleration task test run spectrum of a certain type of turbine disc, comprising the following steps:

[0052] As an embodiment of the present application, the specific steps of step S1 are as follows:

[0053] The intermediate flight section data is extracted from the studied load spectrum (measured temperature spectrum and speed spectrum) for point screening. The main method is to extract all extreme values of the intermediate flight section, and then judge each extracted extreme value from the beginning. Whether the rising and falling judgment amplitude exceeds the set screening threshold, if it exceeds, it is retained, otherwise it is deleted (that is, while retaining the loading and unloading path of the measured load spectrum, small cycles and disturbance signals affecting damage calculation are deleted).

[0054] First and last equal, after the screening is completed, if the values at the beginning and the end are not equal, a point equal to the value at the beginning is added at the end, and a preliminary processed filter spectrum is obtained.

[0055] Point increase, that is, some points of the original load spectrum are added between two points with consistent change trend, but it is ensured to meet the change trend, so that the final processed rain flow filter spectrum (the rain flow filter spectrum is the speed spectrum and temperature spectrum obtained by regularization processing, which is the rain flow filter spectrum obtained by rain flow filtering of the measured temperature spectrum and speed spectrum) is obtained. The formula of the rain flow filter threshold is as follows:

[0056] △%=(G max -G min )×100%

[0057] Wherein, △% is the rain flow filter threshold, G max is the maximum amplitude in the load history, and G min is the minimum amplitude in the load history.

[0058] The regularized speed spectrum and temperature spectrum are applied to the turbine disc for thermal-solid coupling analysis to compile the temperature spectrum and stress spectrum of the dangerous point.

[0059] As an embodiment of the present application, the specific steps of step S2 are as follows:

[0060] Based on the stress-temperature combinations of the dangerous points at different load-holding speeds obtained in step 1, creep tests are performed on a creep testing machine until the material is broken by creep, and the corresponding creep rupture times t are obtained under different stress-temperature conditions f , the fracture strain ε f , and the minimum creep rate ε m .

[0061] As an embodiment of the present application, the specific steps of step S3 are as follows:

[0062] Based on the creep data of the material obtained in step 2, the creep damage tolerance factor calculation expression λ = ε f / (ε m × t f ) proposed in step 3 is brought in, and the creep damage tolerance factor values corresponding to different stress-temperature combinations are obtained.

[0063] As an embodiment of the present application, the specific steps of step S4 are as follows:

[0064] Based on the creep damage tolerance factor values obtained in step 3, according to the fact that when 1 < λ < 2.5, the failure mode is grain boundary cavitation, when 2.5 < λ < 5, the failure mode is necking, and when λ > 5, the failure mode is mainly microstructure instability of precipitate coarsening, the maximum creep states of the stress-temperature combinations with the creep damage tolerance factor values respectively between 1 < λ < 2.5, 2.5 < λ < 5, and λ > 5 are determined.

[0065] As an embodiment of the present application, the specific steps of step S5 are as follows:

[0066] Based on the stress-temperature combinations of the maximum creep states determined in step 4, the damage tolerance factor is analyzed, the maximum creep load state in the failure mode consistency interval is determined, and finally the intermediate maximum state load-holding speed in the aero-engine acceleration task test run-up spectrum is determined as the intermediate state load-holding speed in the aero-engine acceleration task test run-up spectrum.

[0067] Now taking the measured temperature and speed data of an aero-engine test run as an embodiment, the material of the turbine disc of the aero-engine is GH4169, and an example analysis of the method of the present application is performed.

[0068] The rainflow filtering program is used to normalize the aero-engine speed and temperature spectrum (shown in FIG. 2), and small loads are deleted, and the normalized measured temperature spectrum and speed spectrum are obtained, and the processing effects of the speed spectrum and the temperature spectrum are shown in FIGS. 3 and 4, respectively. Figure 2 Figure 3 Figure 4 , Figure 3 ​​The normalized speed spectrum of the actual aero-engine, Figure 4 The normalized temperature spectrum of the actual aero-engine.

[0069] The speed spectrum and the temperature spectrum are applied to the high-pressure turbine disc to compile a dangerous point temperature spectrum and a stress spectrum (as shown in Figure 5 The dangerous point temperature stress combinations (σ i ,T i ) of the turbine disc under different holding speeds are obtained and shown in Table 1.

[0070] Table 1 Dangerous point temperature stress combinations of the turbine disc under different holding speeds

[0071]

[0072] High-temperature creep tests are respectively conducted under the temperature stress combinations in Table 1 to obtain corresponding creep rupture times t f , fracture strains ε f , and minimum creep rates ε m .

[0073] Based on the obtained creep rupture times t f , fracture strains ε f , and minimum creep rates ε m , and according to a creep damage tolerance factor calculation expression λ = ε f / (ε m × t f ), the corresponding creep damage tolerance factors under each temperature stress creep load combination can be calculated and shown in Table 2.

[0074] Table 2 Corresponding damage tolerance factor values under different temperature stress creep load combinations

[0075]

[0076] The failure mode consistency interval is divided for different stress temperature combinations (σ i ,T i ), and the creep damage tolerance factors obtained in Table 2 correspond to the failure mode consistency interval. The creep damage tolerance factors of serial numbers 1-6 are all greater than 5 and are in the same failure mode consistency interval.

[0077] Based on the divided failure mode consistency interval and in combination with Table 1 and Table 2, serial number 1 is the maximum state speed in the interval, i.e., the speed of serial number 1 is determined as the intermediate state holding speed in the acceleration mission test spectrum of the aero-engine, so that the intermediate maximum state holding speed in the acceleration mission test spectrum of the aero-engine is finally determined as the intermediate state holding speed in the acceleration mission test spectrum of the aero-engine, and a schematic diagram is shown in Figure 6 , in which r1-r7 are different stress temperature combinations (σi T i ) state.

[0078] It should be noted that the parts of the present application not involved are the same as or can be realized by the prior art. The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for determining the intermediate state load-holding speed in an aircraft engine acceleration mission test spectrum, characterized in that: The following steps are involved: Step 1: Regularize the measured temperature spectrum and speed spectrum of the comprehensive mission spectrum test, and apply the regularized measured temperature spectrum and speed spectrum to the high-pressure turbine disk of the key aircraft engine component to compile the stress spectrum and temperature spectrum of the dangerous point; Step 2: obtain the creep rupture time, rupture strain and minimum creep rate corresponding to different stress-temperature combinations through high-temperature creep tests of the material; Step 3, based on the fracture time, minimum creep rate and fracture strain, the creep damage tolerance factor under the corresponding stress-temperature combination is obtained; Step 4: Based on the creep damage tolerance factor, the creep damage tolerance factor value corresponding to each level of creep load is calculated, and the failure modes of different stress temperatures are divided into consistency intervals; Step 5: Analyze the damage tolerance factor, determine the maximum creep load state in the failure mode consistency interval, and finally determine the intermediate maximum state load-keeping speed in the aircraft engine acceleration mission test spectrum.

2. The method for determining the intermediate state load-holding speed in the aircraft engine acceleration mission test spectrum according to claim 1, characterized in that: In step 1, the measured temperature spectrum and speed spectrum of the comprehensive task spectrum test are normalized, which means that the small cycles and disturbance signals that affect the damage calculation are deleted while retaining the loading and unloading paths of the measured load spectrum.

3. The method for determining the intermediate state load-holding speed in an aircraft engine acceleration mission test spectrum according to claim 1, characterized in that: In step 2, different stress-temperature combinations (σ i ,T i ) corresponding to creep rupture time, fracture strain, and minimum creep rate: The high temperature creep test of the material is carried out on a creep testing machine, and a certain number of different stress-temperature combinations (σ i ,T i ) creep test under load, the creep deformation is measured using an extensometer and recorded at fixed time intervals until the material creep ruptures, and the creep rupture time, rupture strain, and minimum creep rate are obtained.

4. The method for determining the intermediate state load-holding speed in an aircraft engine acceleration mission test spectrum according to claim 1, characterized in that: In step 3, the process of establishing the fracture time, minimum creep rate, and fracture strain and obtaining the creep damage tolerance factor under the corresponding stress-temperature combination is as follows: Based on the obtained creep rupture time, rupture strain, and minimum creep rate, the creep damage tolerance factor solution expression is established: λ=e f / (e m ×t f ) Where λ represents the creep damage tolerance factor, ε f represents the fracture strain, ε m represents the minimum creep rate, t f represents creep rupture time; Based on the creep damage tolerance factor, the corresponding stress-temperature combination (σ i ,T i ) under creep damage tolerance factor.

5. The method for determining the intermediate state load-holding speed in an aircraft engine acceleration mission test spectrum according to claim 1, characterized in that: In step 4, based on the creep damage tolerance factor, the creep damage tolerance factor value corresponding to each level of creep load is calculated, and the failure modes of different stress temperatures are divided into consistency intervals as follows: The stress-temperature combination (σ i ,T i ) creep load is accelerated to the maximum creep state in the consistent damage range, and the ... i ,T i ) Failure mode consistency interval division: When 1<λ<2.5, the failure mode is grain boundary voids, when 2.5<λ<5, the failure mode is necking, and when λ>5, the failure mode is microstructural instability characterized by coarsening of precipitates.

6. The method for determining the intermediate state load-holding speed in an aircraft engine acceleration mission test spectrum according to claim 1, characterized in that: In step 5, it is finally determined that the intermediate maximum state load-keeping speed in the aircraft engine acceleration mission test spectrum is the intermediate state load-keeping speed in the aircraft engine acceleration mission test spectrum.

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