Method and system for analyzing crack growth rate of high-temperature thin-wall plate and application

Abstract

The invention relates to the technical field of aero-engines, and discloses a high-temperature thin-wall plate crack growth rate analysis method and system and application, fracture analysis is carried out on a crack source area at an examination position of a thin-wall plate, the initial crack growth rate of a crack is obtained, and then the first nominal stress of the thin-wall plate is inversely calculated; carrying out simulation analysis on the thin-wall plate with the initial crack and without the initial crack to obtain a stress distribution form of the thin-wall plate so as to extract a second nominal stress and a third nominal stress of the examination part; correcting the nominal stress under different crack lengths by combining the initial crack propagation rate and the corresponding nominal stress; and finally, calculating through the crack propagation model and the material curve to obtain crack propagation rates under different cracks. According to the method, support can be provided for subsequent crack propagation trend prediction of the thin-wall plate, and a powerful basis can be provided for determination of the critical crack length of the thin-wall plate.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engines and discloses a method, system and application for analyzing crack growth rate of a high-temperature thin-walled plate. Background Art

[0002] Aircraft engine afterburner and nozzle components utilize numerous thin-walled panels. These components are susceptible to cracking under the complex temperature and flow conditions experienced in their operating environments. To balance engine safety and economic efficiency, it is necessary to establish a standard for acceptable crack lengths in thin-walled panels. If a crack exceeds this standard, it must be replaced promptly; otherwise, it can continue to be used. Therefore, establishing a reasonable and reliable crack length standard is crucial to engine safety.

[0003] Accurately estimating crack growth rates supports the development of reasonable and reliable crack length standards. Existing methods for evaluating crack growth rates rely on finite element stress analysis results combined with crack growth models. However, the complex operating environment of an engine makes it difficult to accurately obtain accurate loads, and stress distributions derived solely from load distribution simulations are unable to accurately predict actual stress levels. Furthermore, the loads that cause crack growth in thin-walled panels are often internal stresses generated by temperature or pressure loads. When local cracks appear, the stress distribution within the thin-walled component redistributes, leading to subsequent changes in the stress intensity factor at the crack tip. Consequently, the traditional finite element method struggles to meet engineering requirements when analyzing crack growth rates in high-temperature thin-walled components. Summary of the Invention

[0004] The purpose of the present invention is to provide a method, system and application for analyzing the crack growth rate of high-temperature thin-walled panels, which can provide support for the prediction of subsequent crack growth trends of thin-walled panels and provide a strong basis for determining the critical crack length of thin-walled panels.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is: A method for analyzing crack growth rate of high-temperature thin-walled plates, comprising: Obtaining a load level of a thin-walled plate under a working state, conducting a life test on the thin-walled plate under the same load level until a crack appears at a test position of the thin-walled plate, and obtaining a fatigue band width at the initial position of the crack through fracture analysis; Determining the initial crack growth rate based on the fatigue band width, calculating the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculating the first nominal stress at the initial crack growth position using the Paris formula; Conduct stress analysis of a crack-free thin-walled plate using a finite element analysis method to obtain a second nominal stress at a test position of the thin-walled plate under the working state; A finite element analysis method is used to perform stress analysis on a thin-walled plate with an initial crack at an assessment position, to obtain a third nominal stress of the thin-walled plate with an initial crack in a working state, and a ratio of the first nominal stress to the second nominal stress is used as a correction coefficient to correct the third nominal stress to obtain a corrected fourth nominal stress; According to the fourth nominal stress, the Paris formula is used to calculate the stress intensity factor of the thin-walled plate with an initial crack, and based on the crack propagation curve of the thin-walled plate material, the crack propagation rate of the thin-walled plate with an initial crack under working conditions is analyzed and obtained.

[0006] Furthermore, the stress intensity factor at the initial crack growth ,in 、 is the fitting parameter in the crack growth curve of the thin-walled plate material, is the stress intensity factor at the crack location, is the initial crack growth rate.

[0007] Furthermore, the first nominal stress at the initial crack extension position ,in is the stress shape factor, The value range is 1 to 1.2. is the first nominal stress at the initial crack extension position, The distance from the fatigue strip to the fatigue source area is measured in fracture analysis.

[0008] Furthermore, the modified fourth nominal stress ,in is the first nominal stress, is the second nominal stress, is the third nominal stress; the crack growth rate of a thin-walled plate with an initial crack under working conditions is ,in is the initial crack length.

[0009] To achieve the above technical effects, the present invention provides a high-temperature thin-walled plate crack growth rate analysis system, comprising: a data acquisition module for obtaining, based on a load level of the thin-walled plate in a working state and a life test of the thin-walled plate under the same load level, a fatigue band width at an initial crack position after a crack appears at a test position of the thin-walled plate; a first analysis module for determining the initial crack growth rate based on the fatigue band width, calculating the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculating the first nominal stress at the initial crack growth position using the Paris formula; A simulation analysis module is used to perform stress analysis of a crack-free thin-walled plate using a finite element analysis method to obtain a second nominal stress at a test position of the thin-walled plate under the working state; The second analysis module is used to perform stress analysis of the thin-walled plate with an initial crack at the assessment position using a finite element analysis method to obtain a third nominal stress of the thin-walled plate with the initial crack in the working state, and to correct the third nominal stress using the ratio of the first nominal stress to the second nominal stress as a correction coefficient to obtain a corrected fourth nominal stress; A crack growth rate determination module is used to calculate the stress intensity factor of the thin-walled plate with an initial crack using the Paris formula based on the fourth nominal stress, and to analyze and obtain the crack growth rate of the thin-walled plate with an initial crack under working conditions based on the crack growth curve of the thin-walled plate material.

[0010] Furthermore, in the first analysis module, the stress intensity factor at the initial crack expansion is ,in 、 is the fitting parameter in the crack growth curve of the thin-walled plate material, is the stress intensity factor at the crack location, is the initial crack growth rate.

[0011] Furthermore, in the first analysis module, the first nominal stress at the initial crack extension position is ,in is the stress shape factor, The value range is 1 to 1.2. is the first nominal stress at the initial crack extension position, The distance from the fatigue strip to the fatigue source area is measured in fracture analysis.

[0012] Furthermore, in the second analysis module, the fourth nominal stress after correction ,in is the first nominal stress, is the second nominal stress, is the third nominal stress; the crack growth rate of a thin-walled plate with an initial crack under working conditions is ,in is the initial crack length.

[0013] To achieve the above technical effects, the present invention further provides an application of a high-temperature thin-walled plate crack growth rate analysis method, which is used to analyze and obtain the critical crack growth length of a thin-walled plate with an initial crack based on the high-temperature thin-walled plate crack growth rate analysis method, including: The first critical crack length of the thin-walled plate is obtained by analysis based on the load on the bearing surface of the thin-walled plate, the tensile strength of the thin-walled plate material, and the dimensional parameters of the thin-walled plate; the second critical crack length of the thin-walled plate is obtained by analysis based on the fracture toughness of the thin-walled plate material and the modified fourth nominal stress; Step 7: Taking the minimum value of the first critical crack length and the second critical crack length as the critical propagation crack length of the thin-walled plate with the initial crack.

[0014] Furthermore, the first critical crack length ,in is the width of the bearing surface of the thin-walled plate, The thickness of the bearing surface of thin-walled panels, is the tensile strength of the thin-walled plate material, is the load on the thin-walled plate bearing surface, It can be obtained through finite element simulation analysis; the second critical crack length ,in is the stress shape factor, The value range is 1 to 1.2. is the fracture toughness of thin-walled plate material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention can provide support for the prediction of subsequent crack growth trends of thin-walled plates and provide a strong basis for determining the critical crack length of thin-walled plates.

[0016] 2. Based on the initial crack growth rate, the present invention combines the component characteristics of thin-walled panels and stress analysis results to obtain the crack growth rate under different crack lengths, and then estimates the unstable growth crack length, realizing accurate analysis of the acceptable critical crack length of thin-walled panels and ensuring the test safety of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Flowchart of the crack growth rate analysis method for high-temperature thin-walled panels in Example 1 or 2; Figure 2 This is a structural block diagram of the crack growth rate analysis system for high-temperature thin-walled panels in Example 1; Among them, 1. Data acquisition module; 2. First analysis module; 3. Simulation analysis module; 4. Second analysis module; 5. Crack growth rate determination module. DETAILED DESCRIPTION

[0018] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0019] Example 1 See also Figure 1 and Figure 2 , a method for analyzing crack growth rate of high-temperature thin-walled plates, comprising: Obtaining a load level of a thin-walled plate under a working state, conducting a life test on the thin-walled plate under the same load level until a crack appears at a test position of the thin-walled plate, and obtaining a fatigue band width at the initial position of the crack through fracture analysis; Determining the initial crack growth rate based on the fatigue band width, calculating the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculating the first nominal stress at the initial crack growth position using the Paris formula; Conduct stress analysis of a crack-free thin-walled plate using a finite element analysis method to obtain a second nominal stress at a test position of the thin-walled plate under the working state; A finite element analysis method is used to perform stress analysis on a thin-walled plate with an initial crack at an assessment position, to obtain a third nominal stress of the thin-walled plate with an initial crack in a working state, and a ratio of the first nominal stress to the second nominal stress is used as a correction coefficient to correct the third nominal stress to obtain a corrected fourth nominal stress; According to the fourth nominal stress, the Paris formula is used to calculate the stress intensity factor of the thin-walled plate with an initial crack, and based on the crack propagation curve of the thin-walled plate material, the crack propagation rate of the thin-walled plate with an initial crack under working conditions is analyzed and obtained.

[0020] In this embodiment, by performing fracture analysis on the crack source area at the test position of the thin-walled plate, the initial crack growth rate of the crack is obtained, and then the first nominal stress of the thin-walled plate is inversely calculated; then, by performing simulation analysis on the thin-walled plate with and without initial cracks, the stress distribution form of the thin-walled plate is obtained to extract the second nominal stress and the third nominal stress of the test position; by combining the initial crack growth rate and the corresponding nominal stress, the nominal stress under different crack lengths is corrected; finally, the crack growth rate under different cracks is calculated through the crack growth model and material curve, which can provide support for the subsequent crack growth trend prediction of the thin-walled plate and provide a strong basis for determining the critical crack length of the thin-walled plate.

[0021] Based on the same inventive concept, this embodiment also provides a high-temperature thin-walled plate crack growth rate analysis system, comprising: Data acquisition module 1 is used to obtain, based on the load level of the thin-walled plate in a working state and based on a life test of the thin-walled plate under the same load level, a fatigue band width at the initial position of the crack after a crack appears at the test position of the thin-walled plate; The first analysis module 2 is used to determine the initial crack growth rate according to the fatigue band width, calculate the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculate the first nominal stress at the initial crack growth position using the Paris formula; Simulation analysis module 3, used to perform stress analysis of crack-free thin-walled plate using finite element analysis method to obtain the second nominal stress of the thin-walled plate under the working state at the test position; The second analysis module 4 is configured to perform stress analysis of the thin-walled plate with an initial crack at the assessment position using a finite element analysis method, obtain a third nominal stress of the thin-walled plate with the initial crack in the working state, and use the ratio of the first nominal stress to the second nominal stress as a correction coefficient to correct the third nominal stress to obtain a corrected fourth nominal stress; The crack growth rate determination module 5 is used to calculate the stress intensity factor of the thin-walled plate with an initial crack based on the fourth nominal stress using the Paris formula, and to analyze and obtain the crack growth rate of the thin-walled plate with an initial crack under working conditions based on the crack growth curve of the thin-walled plate material.

[0022] Example 2 See also Figure 1 , an application of a crack growth rate analysis method for high-temperature thin-walled plates, including: Step 1: Obtain the load level of the thin-walled plate under the working state, conduct a life test on the thin-walled plate under the same load level until a crack appears at the test position of the thin-walled plate, and obtain the fatigue band width at the initial position of the crack through fracture analysis; In this embodiment, by obtaining the load level of the thin-walled plate under working conditions, a life test is conducted on the thin-walled plate under the same load level, fatigue cracks are obtained at the test position, and the fatigue band width at the initial position of the crack is obtained through fracture analysis.

[0023] Step 2: Determine the initial crack growth rate based on the fatigue band width, calculate the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculate the first nominal stress at the initial crack growth position using the Paris formula; In this embodiment, in the fracture analysis, the initial crack growth rate of the thin-walled plate can be obtained by measuring the fatigue strip width. ( is a commonly used expression, in which is the crack length, The initial crack growth rate obtained by fracture analysis is the actual test result, which is more accurate than the crack growth rate obtained by simulation method. ,in 、 is the fitting parameter in the crack growth curve of the thin-walled plate material, is the stress intensity factor at the crack location.

[0024] The first nominal stress at the initial crack growth position ,in is the stress shape factor, The value range is 1 to 1.2. is the first nominal stress at the initial crack extension position, To measure the distance from the fatigue strip to the fatigue source area in fracture analysis, the value of this distance should be the same as The value of corresponds to the distance between the fatigue strip position and the fatigue source area.

[0025] Step 3: Use the finite element analysis method to carry out stress analysis of crack-free thin-walled panels to obtain the second nominal stress of the thin-walled panel under the working state. ; Step 4: Use the finite element analysis method to carry out stress analysis of the thin-walled plate with initial cracks at the test position to obtain the third nominal stress of the thin-walled plate with initial cracks in the working state. , using the first nominal stress and the second nominal stress The ratio of the third nominal stress is used as a correction factor. Make corrections and get the corrected fourth nominal stress ; In this embodiment, the fourth nominal stress after correction is obtained .

[0026] Step 5: Calculate the stress intensity factor of the thin-walled plate with the initial crack using the Paris formula based on the fourth nominal stress, and analyze and obtain the crack growth rate of the thin-walled plate with the initial crack under working conditions based on the crack growth curve of the thin-walled plate material; In this embodiment, the fourth nominal stress after correction is Substituting into the Paris formula, the stress intensity factor of the thin-walled plate with initial cracks is calculated , is the initial crack length. The crack growth rate of the thin-walled plate with initial cracks under working conditions is calculated by fitting parameters in the crack growth curve of the thin-walled plate material. .

[0027] Step 6: Analyze and obtain the first critical crack length of the thin-walled plate based on the load on the thin-walled plate bearing surface, the tensile strength of the thin-walled plate material, and the dimensional parameters of the thin-walled plate; and analyze and obtain the second critical crack length of the thin-walled plate based on the fracture toughness of the thin-walled plate material and the modified fourth nominal stress; In this embodiment, the first critical crack length ,in is the width of the bearing surface of the thin-walled plate (determined according to the characteristics of the part and the direction of the load), The thickness of the bearing surface of thin-walled panels, is the tensile strength of the thin-walled plate material, is the load on the thin-walled plate bearing surface, It can be obtained through finite element simulation analysis. The second critical crack length ,in is the stress shape factor, The value range is 1 to 1.2. is the fracture toughness of thin-walled plate material.

[0028] Step 7: Take the minimum value of the first critical crack length and the second critical crack length as the critical extension crack length of the thin-walled plate with initial crack .

[0029] Based on the initial crack growth rate, this embodiment combines the component characteristics and stress analysis results of the thin-walled plate to obtain the crack growth rate at different crack lengths, and then estimates the unstable growth crack length, achieving accurate analysis of the acceptable critical crack length of the thin-walled plate and ensuring the test safety of the engine.

[0030] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for analyzing crack growth rate of high-temperature thin-walled panels, characterized in that: include: Obtaining a load level of a thin-walled plate under a working state, conducting a life test on the thin-walled plate under the same load level until a crack appears at a test position of the thin-walled plate, and obtaining a fatigue band width at the initial position of the crack through fracture analysis; Determining the initial crack growth rate based on the fatigue band width, calculating the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculating the first nominal stress at the initial crack growth position using the Paris formula; Conduct stress analysis of a crack-free thin-walled plate using a finite element analysis method to obtain a second nominal stress at a test position of the thin-walled plate under the working state; A finite element analysis method is used to perform stress analysis on a thin-walled plate with an initial crack at an assessment position, to obtain a third nominal stress of the thin-walled plate with an initial crack in a working state, and a ratio of the first nominal stress to the second nominal stress is used as a correction coefficient to correct the third nominal stress to obtain a corrected fourth nominal stress; According to the fourth nominal stress, the Paris formula is used to calculate the stress intensity factor of the thin-walled plate with an initial crack, and based on the crack propagation curve of the thin-walled plate material, the crack propagation rate of the thin-walled plate with an initial crack under working conditions is analyzed and obtained.

2. The method for analyzing crack growth rate of high-temperature thin-walled panels according to claim 1, characterized in that: Stress intensity factor at initial crack growth ,in 、 is the fitting parameter in the crack growth curve of the thin-walled plate material, is the stress intensity factor at the crack location, is the initial crack growth rate.

3. The method for analyzing crack growth rate of high-temperature thin-walled panels according to claim 2, characterized in that: The first nominal stress at the initial crack growth position ,in is the stress shape factor, The value range is 1 to 1.

2. is the first nominal stress at the initial crack extension position, The distance from the fatigue strip to the fatigue source area is measured in fracture analysis.

4. The method for analyzing crack growth rate of high-temperature thin-walled panels according to claim 3, characterized in that: Corrected fourth nominal stress ,in is the first nominal stress, is the second nominal stress, is the third nominal stress; the crack growth rate of a thin-walled plate with an initial crack under working conditions is ,in is the initial crack length.

5. A high-temperature thin-walled plate crack growth rate analysis system, characterized in that: include: a data acquisition module for obtaining, based on a load level of the thin-walled plate in a working state and a life test of the thin-walled plate under the same load level, a fatigue band width at an initial crack position after a crack appears at a test position of the thin-walled plate; a first analysis module for determining the initial crack growth rate based on the fatigue band width, calculating the stress intensity factor at the initial crack growth based on the crack growth curve of the thin-walled plate material, and calculating the first nominal stress at the initial crack growth position using the Paris formula; A simulation analysis module is used to perform stress analysis of a crack-free thin-walled plate using a finite element analysis method to obtain a second nominal stress at a test position of the thin-walled plate under the working state; The second analysis module is used to perform stress analysis of the thin-walled plate with an initial crack at the assessment position using a finite element analysis method to obtain a third nominal stress of the thin-walled plate with the initial crack in the working state, and to correct the third nominal stress using the ratio of the first nominal stress to the second nominal stress as a correction coefficient to obtain a corrected fourth nominal stress; A crack growth rate determination module is used to calculate the stress intensity factor of the thin-walled plate with an initial crack using the Paris formula based on the fourth nominal stress, and to analyze and obtain the crack growth rate of the thin-walled plate with an initial crack under working conditions based on the crack growth curve of the thin-walled plate material.

6. The high-temperature thin-walled plate crack growth rate analysis system according to claim 5, characterized in that: In the first analysis module, the stress intensity factor at the initial crack expansion ,in 、 is the fitting parameter in the crack growth curve of the thin-walled plate material, is the stress intensity factor at the crack location, is the initial crack growth rate.

7. The high-temperature thin-walled plate crack growth rate analysis system according to claim 6, characterized in that: In the first analysis module, the first nominal stress at the initial crack extension position ,in is the stress shape factor, The value range is 1 to 1.

2. is the first nominal stress at the initial crack extension position, The distance from the fatigue strip to the fatigue source area is measured in fracture analysis.

8. The high-temperature thin-walled plate crack growth rate analysis system according to claim 7, characterized in that: In the second analysis module, the corrected fourth nominal stress ,in is the first nominal stress, is the second nominal stress, is the third nominal stress; the crack growth rate of a thin-walled plate with an initial crack under working conditions is ,in is the initial crack length.

9. An application of a high-temperature thin-walled plate crack growth rate analysis method, for analyzing and obtaining the critical crack growth length of a thin-walled plate with an initial crack according to any one of claims 1 to 3, characterized in that: include: The first critical crack length of the thin-walled plate is obtained by analysis based on the load on the bearing surface of the thin-walled plate, the tensile strength of the thin-walled plate material, and the dimensional parameters of the thin-walled plate; the second critical crack length of the thin-walled plate is obtained by analysis based on the fracture toughness of the thin-walled plate material and the modified fourth nominal stress; The minimum value of the first critical crack length and the second critical crack length is taken as the critical propagation crack length of the thin-walled plate with an initial crack.

10. The use according to claim 9, characterized in that The first critical crack length ,in is the width of the bearing surface of the thin-walled plate, The thickness of the bearing surface of thin-walled panels, is the tensile strength of the thin-walled plate material, is the load on the thin-walled plate bearing surface, It can be obtained through finite element simulation analysis; the second critical crack length ,in is the stress shape factor, The value range is 1 to 1.

2. is the fracture toughness of thin-walled plate material.

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