Acceleration task test run spectrum compilation method and system considering multiple modes and multiple dangerous points

Abstract

The invention discloses an acceleration task test-run spectrum compilation method and system considering multiple modes and multiple dangerous points, and belongs to the technical field of aero-engine acceleration task test-run spectrums, and the method comprises the steps: obtaining the stress and temperature distribution conditions of parts under different loads and working conditions; selecting examination points of key characteristics in operation of a plurality of parts as potential dangerous points for analysis; fatigue and creep damage calculation and evaluation are carried out on each selected assessment point; statistical analysis is carried out on the rotating speed change rate distribution characteristics in the long-term life test run spectrum, and the switching rate from the slow state to the maximum state is determined; comparing different failure mode damage values of each assessment point; the acceleration task test-run spectrum compiling method and system considering the multiple modes and the multiple dangerous points are suitable for compiling the acceleration task test-run spectrums of most military or civil aero-engines, the damage state of parts in the actual service process can be accurately reflected, and powerful support is provided for optimization of the acceleration task test-run spectrums.

Description

Technical Field

[0001] The present invention belongs to the technical field of acceleration mission test run spectra for aircraft engines, and in particular relates to a method and system for compiling acceleration mission test run spectra that consider multiple modes and multiple danger points. Background Art

[0002] As a complex power system, the core components of aircraft engines, such as fan disks, turbine disks, turbine blades and combustion chamber casings, are subjected to extreme conditions such as high temperature, high pressure and high speed during operation, which places extremely high demands on their structural strength and fatigue life. In order to ensure the safety and reliability of these key components during actual service, they must be tested. However, although the traditional long-term life test spectrum can simulate the real operating environment, it has a long test cycle and high cost, which makes it difficult to meet the needs of modern aircraft engine research and development for rapid testing and optimization.

[0003] As an effective method to shorten the test cycle and accelerate the accumulation of fatigue damage, accelerated mission testing has received widespread attention in recent years. Through a reasonably designed accelerated mission test spectrum, the damage behavior of components in long-term operation can be simulated in a shorter time, thereby significantly reducing the test cost. In previous accelerated mission tests, systematic research on compilation methods was relatively limited, and the compilation conditions were usually too idealized to accurately reflect the damage state of components during actual service. Therefore, it is necessary to develop a new accelerated mission test spectrum compilation method and system that considers multiple modes and multiple danger points to solve existing problems. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for compiling an acceleration task test spectrum taking into account multiple modes and multiple danger points, so as to solve the problem that the method for compiling an acceleration task test spectrum is too idealistic.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points, comprising the following steps:

[0006] Step 1: Perform stress simulation analysis on the components of the research object. Through simulation analysis, obtain the stress and temperature distribution of the components under different loads and working conditions, so as to determine their key stress areas and potential weak points;

[0007] Step 2: Select multiple representative assessment points as potential danger points for key analysis; the selection of assessment points is based on the key characteristics of components during operation; through the reasonable selection of assessment points, it can ensure that the test spectrum is more reasonable and practical;

[0008] Step 3: Using Miner's linear cumulative damage theory, calculate and evaluate fatigue and creep damage for each selected assessment point. Specifically, for each assessment point, first calculate its fatigue damage according to its stress change in the working cycle, and evaluate the degree of material cumulative damage caused by cyclic loads. Then, further calculate creep damage according to the temperature and stress level of the assessment point.

[0009] Step 4: The thermal shock load in the engine comes from the change of temperature. The rate of change of temperature depends largely on the rate of change of speed. When compiling the acceleration task test spectrum, the peak and valley temperature is guaranteed by the speed in the slow-maximum-slow cycle; therefore, in order to ensure the equivalence of thermal shock damage, the distribution characteristics of the speed change rate in the long-term life test spectrum are statistically analyzed to determine the switching rate from the slow state to the maximum state;

[0010] Step 5: Compare the damage values ​​of different failure modes at each assessment point, select the assessment point with the maximum fatigue damage value to convert it into the number of slow-max-slow cycles of the acceleration spectrum, and select the assessment point with the maximum creep damage value to convert it into the maximum state holding time;

[0011] Step 6: Based on the number of slow-maximum-slow cycles, the maximum state holding time and the switching rate from the slow state to the maximum state obtained in the above steps, a gas task test spectrum considering multiple assessment points is compiled;

[0012] Step 7: Perform damage consistency check on the accelerated mission test spectrum compiled considering multiple modes and multiple hazardous points and the original long-term life test spectrum.

[0013] Preferably, in step 2, the selection of assessment points may include the following categories: first, the point of maximum stress, and second, the point of maximum temperature. In addition, positions where both stress and temperature are large may be selected as assessment points to comprehensively evaluate the performance of components under complex working conditions.

[0014] Preferably, in step 3, the fatigue damage calculation of each assessment point uses Miner's linear rule Where n i is the number of cycles applied at a certain stress level, N i is the number of cycles required until failure occurs at this stress level. The creep damage is similarly calculated using Calculate, where t i is the holding time under a certain load level, t ci is the time required for creep rupture at this load level.

[0015] Preferably, in step 5, the fatigue damage value and creep damage value of each assessment point are comprehensively compared, and the assessment point with the largest fatigue damage value is used to convert the slow-maximum-slow cycle number into the acceleration spectrum. Where D I-M-I is the fatigue damage of a single slow-maximum-slow cycle. Preferably, the assessment point with the maximum creep damage is used to convert it into the maximum state retention time of the acceleration spectrum. Where D M is the creep damage per unit time under the maximum state.

[0016] Preferably, in step 7, in order to check the damage consistency between the acceleration task test spectrum compiled with multiple modes and multiple dangerous points and the long-term life test spectrum, the load of the test section of the smooth test piece is corrected by the temperature correction coefficient S(T0)=S(T)·σ b (T0) / σ b (T), S(T0), S(T) represent the stress at temperatures T0 and T respectively; σ b (T0),σ b (T) represents the tensile strength at temperatures T0 and T respectively. A variable cross-section test piece was designed to compare the test results of the accelerated spectrum and the long test spectrum.

[0017] The present invention further provides a system for compiling a test spectrum of an acceleration task considering multiple modes and multiple danger points, comprising:

[0018] Acquisition module, used to obtain the stress and temperature distribution of components under different loads and working conditions;

[0019] The selection module is used to select the key characteristics of multiple components during operation as potential risk points for analysis;

[0020] The calculation and evaluation module is used to calculate and evaluate fatigue and creep damage for each selected assessment point;

[0021] Statistical analysis module, used to statistically analyze the speed change rate distribution characteristics in the long-term life test spectrum and determine the switching rate from the slow state to the maximum state;

[0022] The comparison module is used to compare the damage values ​​of different failure modes at each assessment point, select the assessment point with the maximum fatigue damage value to convert it into the number of slow-max-slow cycles of the acceleration spectrum, and select the assessment point with the maximum creep damage value to convert it into the maximum state holding time;

[0023] A compilation module is used to compile an acceleration task test spectrum according to the number of slow-maximum-slow cycles, the maximum state holding time and the switching rate from the slow state to the maximum state;

[0024] The inspection module is used to inspect the damage consistency between the acceleration mission test spectrum and the long-term life test spectrum.

[0025] The technical effects and advantages of the present invention are as follows: the method and system for compiling an acceleration mission test spectrum taking into account multiple modes and multiple danger points are simple and intuitive, with concise steps and strong versatility. They are applicable to the compilation of acceleration mission test spectrums for most military or civil aviation engines, and can accurately reflect the damage status of components during actual service, providing strong support for the optimization of acceleration mission test spectrums. From the perspective of selecting multiple danger points for assessment, the method for compiling an acceleration mission test spectrum for aviation engines has been innovated, and a method for compiling an acceleration mission test spectrum for typical components with multiple modes and multiple danger points has been proposed, providing a theoretical basis for optimizing the method for compiling an acceleration mission test spectrum, and having extremely strong generalizability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process of the present invention;

[0027] Figure 2 It is a schematic diagram summarizing the creep damage calculation of each assessment point of the method of the present invention;

[0028] Figure 3 It is the speed spectrum of the long-term life test spectrum used in the present invention;

[0029] Figure 4 Acceleration spectrum compiled for the present invention;

[0030] Figure 5 Geometric dimension diagram of the variable cross-section test piece designed for the present invention;

[0031] Figure 6 It is a strain-cycle number curve diagram of the present invention under the long-term life test spectrum and the compiled acceleration spectrum. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention provides Figure 1 A method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points is shown in the figure, comprising the following steps:

[0034] Step 1: Simulate and analyze the turbine blades made of DZ125 directionally solidified high-temperature alloy to obtain the load distribution under different working conditions;

[0035] Step 2: Based on the simulation analysis results in step 1, multiple assessment points are selected to examine the load conditions. They are the point with the largest stress value, the point with the largest temperature value, and the point with both large stress and temperature. The point with both large stress and temperature is determined based on the simulation analysis results, for example, the point with stress and temperature values ​​exceeding 80% of the maximum value is selected. The corresponding specific values ​​are shown in the following table:

[0036]

[0037] Step 3: Use Miner's linear cumulative damage theory to calculate fatigue and creep damage for each selected assessment point. The damage calculation results of each assessment point are as follows: Figure 2 As shown;

[0038] Step 4: To ensure that the accelerated life test spectrum is equivalent to the thermal shock damage of the long-term life test spectrum, a statistical analysis is performed on the speed change rate distribution characteristics in the long-term life test spectrum. Figure 3 As shown; it is calculated that the average time for accelerating from the slow state to the maximum state is 25.1s, and the average time for decelerating from the maximum state to the slow state is 23.5s;

[0039] Step 5: Compare Figure 2 The fatigue damage and creep damage of each test point show that the maximum value of fatigue damage appears at test point 1, while the maximum value of creep damage appears at test point 2;

[0040] According to the principle of damage equivalence, the fatigue damage value at test point 1 is used according to Perform equivalent calculation to determine the maximum-slow-maximum cycle number at this point. At the same time, through the creep damage value at the test point 2, according to Calculate the maximum state time at this point. After relevant calculations, the maximum-slow-maximum cycle number that can be converted to the fatigue damage value at test point 1 at 700°C is 15. At 900°C, all other low-power states are accelerated to be equivalent to the maximum state, and the maximum state duration after conversion is 2270s;

[0041] Step 6: The number of maximum-slow-maximum cycles of the converted acceleration task test spectrum is 15, and the maximum state duration is 2270s. After deducting the maximum state duration contained in 15 slow-maximum-slow cycles, the concentrated maximum state duration is 1220s, the total acceleration spectrum time is 4045s, the total time of the original long-term life test spectrum is 6243s, and the acceleration coefficient is 1.54; the compiled acceleration task test spectrum is as follows Figure 4 ;

[0042] Step 7: Damage consistency test between the acceleration mission test spectrum and the long-term life test spectrum. The specific operations are as follows:

[0043] At the same time, the creep fatigue damage of test point 1 and test point 2 is simulated in the test, and the test piece needs to reflect different stress profiles and temperature profiles in the test. Different stress profiles can be achieved by designing a variable cross-section test piece and changing the cross-sectional area of ​​the test section to achieve the effect of segmented stress.

[0044] Since the temperature in the high-temperature furnace is set to a fixed value during the test, it is impossible to achieve segmented temperature control in the high-temperature furnace. Therefore, a temperature correction method is considered to convert the stress profile to the same temperature. The temperature correction coefficient is expressed as:

[0045]

[0046] The stress profile at test point 1 is converted to the stress at test point 2 at 900°C, and the specimen load is corrected using the temperature correction factor. The conversion method is to assume that fatigue creep damage depends on the ratio of stress to material tensile strength. Therefore, the design of the test specimen after stress correction is as follows: Figure 5 As shown;

[0047] S(T0)=S(T)·σ b (T0) / σ b (T)

[0048] In order to verify the effectiveness of the spectrum compilation method, the long-term life test and accelerated task test of the variable cross-section test piece at 700°C were carried out. The test material was DZ125 directionally solidified high-temperature alloy. The test was carried out on a high-temperature electronic creep tester. The results of the accelerated task test and long-term life test are as follows:

[0049]

[0050]

[0051] The test results starting with CS are under the long-term life test spectrum, and the test results starting with JS are under the accelerated task test spectrum. From the test results, it can be analyzed that the average number of complete cycles experienced under the long test spectrum is 34.33 times, and the average number of complete cycles experienced under the accelerated spectrum is 33 times. Compared with the long test spectrum, the error of the average number of complete cycles experienced by the two is -3.87%, which shows that the accelerated spectrum and the long test spectrum are quite equivalent.

[0052] The strain-cycle number curves under the accelerated task test spectrum and long-term life test spectrum compiled considering multiple assessment points are as follows: Figure 6From the curve shape, CS-3 and JS-2 are almost overlapped in the whole process, while CS-1 and JS-2 are highly consistent in shape. From the strain growth rate of the acceleration spectrum and the long test spectrum, the strain growth rate can be evaluated by comparing the slope of the curve. The steep increase phase curves of CS-1 and JS-1 are almost parallel, indicating that the rate of accumulated strain of the material under these two conditions is equivalent. From the final strain failure point of view, the average final failure strain under the long-term life test spectrum is 14.52%, and the average final failure strain under the accelerated task test spectrum is 16.01%. Compared with the long test spectrum, the error between the two is 10.26%. Multiple angles show that the accelerated task test spectrum compiled with multiple assessment points is equivalent to the original long-term life test spectrum in damage.

[0053] In summary, the present invention has established a method for compiling a typical component acceleration task test spectrum that takes into account multiple modes and multiple danger points based on the damage danger points of key components, providing a theoretical basis for optimizing the compilation method of the acceleration task test spectrum of aircraft engines. The method is simple and intuitive, with concise steps and strong versatility. It can be applied to the compilation of most military or civil aircraft engine acceleration task test spectra and has strong promotion potential.

[0054] The present invention further provides a system for compiling a test spectrum of an acceleration task considering multiple modes and multiple danger points, comprising:

[0055] Acquisition module, used to obtain the stress and temperature distribution of components under different loads and working conditions;

[0056] The selection module is used to select the key characteristics of multiple components during operation as potential risk points for analysis;

[0057] The calculation and evaluation module is used to calculate and evaluate fatigue and creep damage for each selected assessment point;

[0058] Statistical analysis module, used to statistically analyze the speed change rate distribution characteristics in the long-term life test spectrum and determine the switching rate from the slow state to the maximum state;

[0059] The comparison module is used to compare the damage values ​​of different failure modes at each assessment point, select the assessment point with the maximum fatigue damage value to convert it into the number of slow-max-slow cycles of the acceleration spectrum, and select the assessment point with the maximum creep damage value to convert it into the maximum state holding time;

[0060] A compilation module is used to compile an acceleration task test spectrum according to the number of slow-maximum-slow cycles, the maximum state holding time and the switching rate from the slow state to the maximum state;

[0061] The inspection module is used to inspect the damage consistency between the acceleration mission test spectrum and the long-term life test spectrum.

[0062] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for compiling a test spectrum for an acceleration task considering multiple modes and multiple danger points, characterized in that: include: Obtain stress and temperature distribution of components under different loads and working conditions; Select key characteristics of multiple components during operation as potential risk points for analysis; Calculate and evaluate fatigue and creep damage for each selected assessment point; Statistically analyze the speed change rate distribution characteristics in the long-term life test spectrum to determine the switching rate from the slow state to the maximum state; Compare the damage values ​​of different failure modes at each assessment point, select the assessment point with the maximum fatigue damage value to convert it into the number of slow-max-slow cycles of the acceleration spectrum, and select the assessment point with the maximum creep damage value to convert it into the maximum state holding time; Compile the acceleration task test spectrum according to the number of slow-maximum-slow cycles, the maximum state holding time, and the switching rate from the slow state to the maximum state; Check the damage consistency between the accelerated mission test spectrum and the long-term life test spectrum.

2. The method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points according to claim 1, characterized in that: The key characteristics of the component during operation include: the point of maximum stress of the component, the point of maximum temperature and the point where both stress and temperature are relatively large.

3. The method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points according to claim 1, characterized in that: The obtaining of stress and temperature distribution of components under different loads and working conditions includes: obtaining stress and temperature distribution of components under different loads and working conditions through simulation analysis.

4. The method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points according to claim 1, characterized in that: The calculation and evaluation of fatigue and creep damage for each selected assessment point includes: calculating and evaluating fatigue and creep damage for each selected assessment point by using Miner linear cumulative damage algorithm; specifically including: Calculate fatigue damage; Calculate the creep damage based on the temperature and stress level at the assessment point.

5. The method for compiling a test spectrum of an acceleration task considering multiple modes and multiple danger points according to claim 4, characterized in that: The calculation of fatigue damage includes: cumulative fatigue damage calculation value Where n i is the number of cycles applied at a certain stress level, N i D is the number of cycles required until failure occurs at this stress level. f is the calculated value of cumulative fatigue damage.

6. The method for compiling a test spectrum for acceleration tasks considering multiple modes and multiple danger points according to claim 4, characterized in that: The creep damage calculation based on the temperature and stress level of the test point includes: Calculate, where t i is the holding time under a certain load level, t ci is the time required for creep rupture under this load level, D c Calculated value for cumulative creep damage.

7. The method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points according to claim 1, characterized in that: The method of converting the maximum fatigue damage value of the assessment point into the number of slow-maximum-slow cycles of the acceleration spectrum includes: comparing the fatigue damage value and the creep damage value of each assessment point, and converting the maximum fatigue damage value of the assessment point into the number of slow-maximum-slow cycles of the acceleration spectrum. Where D f is the total fatigue damage of each cycle, where D I-M-I is the fatigue damage of a single slow-maximum-slow cycle, and N is the number of converted cycles.

8. The method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points according to claim 1, characterized in that: The method of converting the maximum state holding time of the assessment point with the maximum creep damage into the maximum state holding time of the acceleration spectrum includes: Where: D c is the calculated value of cumulative creep damage, D M is the creep damage per unit time under the maximum state.

9. The method for compiling an acceleration task test spectrum considering multiple modes and multiple danger points according to claim 1, characterized in that: The damage consistency of the acceleration task test spectrum and the long-term life test spectrum includes: correcting the test section load of the smooth test piece by a temperature correction coefficient S(T0)=S(T·σ b (T0) / σ b (T), where S(T0) and S(T) represent the stress at temperatures T0 and T respectively; σ b (T0),σ b (T) represents the tensile strength at temperatures T0 and T, respectively. A variable-section test piece is designed based on the correction results, and the test results of the accelerated spectrum and the long test spectrum are compared.

10. A system for compiling acceleration task test spectra considering multiple modes and multiple danger points, characterized in that: include: Acquisition module, used to obtain the stress and temperature distribution of components under different loads and working conditions; The selection module is used to select the key characteristics of multiple components during operation as potential risk points for analysis; The calculation and evaluation module is used to calculate and evaluate fatigue and creep damage for each selected assessment point; Statistical analysis module, used to statistically analyze the speed change rate distribution characteristics in the long-term life test spectrum and determine the switching rate from the slow state to the maximum state; The comparison module is used to compare the damage values ​​of different failure modes at each assessment point, select the assessment point with the maximum fatigue damage value to convert it into the number of slow-max-slow cycles of the acceleration spectrum, and select the assessment point with the maximum creep damage value to convert it into the maximum state holding time; A compilation module is used to compile an acceleration task test spectrum according to the number of slow-maximum-slow cycles, the maximum state holding time and the switching rate from the slow state to the maximum state; The inspection module is used to inspect the damage consistency between the acceleration mission test spectrum and the long-term life test spectrum.

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