A method, system and application for analyzing crack propagation rate in high-temperature thin-walled plates.

Abstract

This invention relates to the field of aero-engine technology, and discloses a method, system, and application for analyzing the crack propagation rate of high-temperature thin-walled plates. The method involves fracture surface analysis of the crack initiation zone at the test location of the thin-walled plate to obtain the initial crack propagation rate, followed by back-calculation of the first nominal stress of the thin-walled plate. Simulation analysis is then performed on thin-walled plates with and without initial cracks to obtain the stress distribution pattern, thereby extracting the second and third nominal stresses at the test location. The nominal stress is corrected for different crack lengths by combining the initial crack propagation rate and the corresponding nominal stress. Finally, the crack propagation rate for different crack lengths is calculated using a crack propagation model and material curves. This invention can provide support for predicting the subsequent crack propagation trend of thin-walled plates and provide a strong basis for determining the critical crack length of thin-walled plates.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and discloses a method, system and application for analyzing the crack propagation rate of high-temperature thin-walled plates. Background Technology

[0002] Thin-walled plates are extensively used in the afterburner and nozzle components of aero engines. These thin-walled plates are prone to cracking under the complex temperature and flow field conditions of the operating environment. In order to balance the safety and economy of the engine, it is necessary to establish acceptable crack length standards for thin-walled plates. Once the crack length exceeds the standard, the plate needs to be replaced in time; otherwise, it can continue to be used. Therefore, establishing reasonable and reliable crack length standards is crucial to engine safety.

[0003] Accurately predicting crack propagation rates is crucial for establishing reasonable and reliable crack length standards. Existing methods for assessing crack propagation rates rely on finite element stress analysis results combined with crack propagation models. However, the complex operating environment of engines makes it difficult to obtain accurate loads, and stress distribution obtained solely through load distribution simulation is insufficient to accurately predict actual stress levels. Furthermore, the loads that cause crack propagation in thin-walled plates are often internal stresses generated by temperature or pressure loads. When a local crack appears, the internal stress distribution in the thin-walled component redistributes, leading to successive changes in the stress intensity factor at the crack tip. Therefore, the traditional finite element method struggles to meet engineering requirements in terms of calculation accuracy when analyzing crack propagation rates in high-temperature thin-walled components. Summary of the Invention

[0004] The purpose of this invention is to provide a method, system, and application for analyzing the crack propagation rate of thin-walled plates at high temperatures, which can provide support for predicting the subsequent crack propagation trend of thin-walled plates and provide a strong basis for determining the critical crack length of thin-walled plates.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0006] A method for analyzing the crack propagation rate of high-temperature thin-walled plates includes:

[0007] The load level of the thin-walled plate under working conditions is obtained, and a life test under the same load level is carried out on the thin-walled plate until a crack appears at the test location of the thin-walled plate. The fatigue strip width at the initial position of the crack is obtained through fracture analysis.

[0008] The initial crack propagation rate is determined based on the fatigue band width. Based on the crack propagation curve of the thin-walled plate material, the stress intensity factor at the initial crack propagation is calculated, and the first nominal stress at the initial crack propagation location is calculated using the Paris formula.

[0009] The finite element method was used to conduct stress analysis on a crack-free thin-walled plate to obtain the second nominal stress at the test location of the thin-walled plate under the working state.

[0010] The finite element method is used to conduct stress analysis on a thin-walled plate with an initial crack at the test location. The third nominal stress of the thin-walled plate with an initial crack under working conditions is obtained. The ratio of the first nominal stress to the second nominal stress is used as a correction coefficient to correct the third nominal stress, and the corrected fourth nominal stress is obtained.

[0011] Based on the fourth nominal stress, the stress intensity factor of the thin-walled plate with initial cracks is calculated using the Paris formula, and the crack propagation rate of the thin-walled plate with initial cracks under working conditions is analyzed based on the crack propagation curve of the thin-walled plate material.

[0012] Furthermore, the stress intensity factor at the initial crack propagation stage ,in , These are the fitting parameters in the crack propagation curve of the thin-walled plate material. The stress intensity factor at the crack location is... The initial crack propagation rate is denoted as .

[0013] Furthermore, the first nominal stress at the initial crack propagation location ,in For stress shape factor, The value range is 1 to 1.2. The first nominal stress at the initial crack propagation location, This is used to measure the distance from the fatigue stripe to the fatigue origin region in fracture analysis.

[0014] Furthermore, the revised fourth nominal stress ,in For the first nominal stress, For the second nominal stress, The third nominal stress; the crack propagation rate of a thin-walled plate with an initial crack under operating conditions. ,in The initial crack length is given.

[0015] To achieve the above technical effects, the present invention provides a crack propagation rate analysis system for high-temperature thin-walled plates, comprising:

[0016] The data acquisition module is used to obtain the fatigue strip width at the initial position of the crack after the crack appears at the test position of the thin-walled plate, based on the load level under the working state of the thin-walled plate and the life test of the thin-walled plate under the same load level.

[0017] The first analysis module is used to determine the initial crack propagation rate based on the fatigue strip width, calculate the stress intensity factor at the initial crack propagation based on the crack propagation curve of the thin-walled plate material, and calculate the first nominal stress at the initial crack propagation position using the Paris formula.

[0018] The simulation analysis module is used to conduct stress analysis on crack-free thin-walled plates using the finite element analysis method, and to obtain the second nominal stress at the test location of the thin-walled plate under the working state.

[0019] The second analysis module is used to perform stress analysis on a thin-walled plate with initial cracks at the test location using the finite element analysis method, to obtain the third nominal stress of the thin-walled plate with initial cracks in the working state, and to correct the third nominal stress by using the ratio of the first nominal stress to the second nominal stress as a correction coefficient, so as to obtain the corrected fourth nominal stress.

[0020] The crack propagation rate determination module is used to calculate the stress intensity factor of the thin-walled plate with initial cracks using the Paris formula based on the fourth nominal stress, and to analyze and obtain the crack propagation rate of the thin-walled plate with initial cracks under working conditions based on the crack propagation curve of the thin-walled plate material.

[0021] Furthermore, in the first analysis module, the stress intensity factor at the initial crack propagation stage... ,in , These are the fitting parameters in the crack propagation curve of the thin-walled plate material. The stress intensity factor at the crack location is... The initial crack propagation rate is denoted as .

[0022] Furthermore, in the first analysis module, the first nominal stress at the initial crack propagation location... ,in For stress shape factor, The value range is 1 to 1.2. The first nominal stress at the initial crack propagation location, This is used to measure the distance from the fatigue stripe to the fatigue origin region in fracture analysis.

[0023] Furthermore, in the second analysis module, the corrected fourth nominal stress ,in For the first nominal stress, For the second nominal stress, The third nominal stress; the crack propagation rate of a thin-walled plate with an initial crack under operating conditions. ,in The initial crack length is given.

[0024] To achieve the above technical effects, the present invention also provides an application of a method for analyzing the crack propagation rate of high-temperature thin-walled plates, used to analyze and obtain the critical propagation crack length of a thin-walled plate with an initial crack based on the method, including:

[0025] The first critical crack length of the thin-walled plate is obtained by analyzing the load on the bearing surface of the thin-walled plate, the tensile strength of the material of the thin-walled plate, and the dimensional parameters of the thin-walled plate; the second critical crack length of the thin-walled plate is obtained by analyzing the fracture toughness of the material of the thin-walled plate and the corrected fourth nominal stress.

[0026] Step 7: Take 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.

[0027] Furthermore, the first critical crack length ,in The width of the bearing surface of the thin-walled plate. The thickness of the bearing surface of thin-walled plates, For the tensile strength of thin-walled plate materials, For the load-bearing surface of thin-walled plate components, The second critical crack length can be obtained through finite element simulation analysis. ,in For stress shape factor, The value range is 1 to 1.2. This refers to the fracture toughness of thin-walled plate materials.

[0028] Compared with the prior art, the beneficial effects of this invention are:

[0029] 1. This invention can provide support for predicting the subsequent crack propagation trend of thin-walled plates and provide a strong basis for determining the critical crack length of thin-walled plates.

[0030] 2. Based on the initial crack propagation rate, this invention combines the component characteristics and stress analysis results of thin-walled plates to obtain the crack propagation rate under different crack lengths, and then predicts the length of unstable propagation cracks, realizing accurate analysis of the acceptable critical crack length of thin-walled plates, and ensuring the test safety of the engine. Attached Figure Description

[0031] Figure 1 This is a flowchart of the crack propagation rate analysis method for high-temperature thin-walled plates in Example 1 or 2;

[0032] Figure 2This is a block diagram of the crack propagation rate analysis system for high-temperature thin-walled plates in Example 1;

[0033] The module comprises: 1. Data acquisition module; 2. First analysis module; 3. Simulation analysis module; 4. Second analysis module; and 5. Crack propagation rate determination module. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0035] Example 1

[0036] See Figure 1 and Figure 2 A method for analyzing the crack propagation rate of high-temperature thin-walled plates, comprising:

[0037] The load level of the thin-walled plate under working conditions is obtained, and a life test under the same load level is carried out on the thin-walled plate until a crack appears at the test location of the thin-walled plate. The fatigue strip width at the initial position of the crack is obtained through fracture analysis.

[0038] The initial crack propagation rate is determined based on the fatigue band width. Based on the crack propagation curve of the thin-walled plate material, the stress intensity factor at the initial crack propagation is calculated, and the first nominal stress at the initial crack propagation location is calculated using the Paris formula.

[0039] The finite element method was used to conduct stress analysis on a crack-free thin-walled plate to obtain the second nominal stress at the test location of the thin-walled plate under the working state.

[0040] The finite element method is used to conduct stress analysis on a thin-walled plate with an initial crack at the test location. The third nominal stress of the thin-walled plate with an initial crack under working conditions is obtained. The ratio of the first nominal stress to the second nominal stress is used as a correction coefficient to correct the third nominal stress, and the corrected fourth nominal stress is obtained.

[0041] Based on the fourth nominal stress, the stress intensity factor of the thin-walled plate with initial cracks is calculated using the Paris formula, and the crack propagation rate of the thin-walled plate with initial cracks under working conditions is analyzed based on the crack propagation curve of the thin-walled plate material.

[0042] In this embodiment, fracture analysis is performed on the crack initiation zone at the test location of the thin-walled plate to obtain the initial crack propagation rate, and then the first nominal stress of the thin-walled plate is calculated. Next, simulation analysis is conducted on thin-walled plates with and without initial cracks to obtain the stress distribution pattern, thereby extracting the second and third nominal stresses at the test location. By combining the initial crack propagation rate and the corresponding nominal stress, the nominal stress under different crack lengths is corrected. Finally, the crack propagation rate under different crack lengths is calculated using a crack propagation model and material curves. This provides support for predicting the subsequent crack propagation trend of the thin-walled plate and provides a strong basis for determining the critical crack length of the thin-walled plate.

[0043] Based on the same inventive concept, this embodiment also provides a high-temperature thin-walled plate crack propagation rate analysis system, including:

[0044] Data acquisition module 1 is used to obtain the fatigue strip width at the initial position of the crack after the crack appears at the test position of the thin-walled plate, based on the load level under the working state of the thin-walled plate and the life test of the thin-walled plate under the same load level.

[0045] The first analysis module 2 is used to determine the initial crack propagation rate based on the fatigue strip width, calculate the stress intensity factor at the initial crack propagation based on the crack propagation curve of the thin-walled plate material, and calculate the first nominal stress at the initial crack propagation position using the Paris formula.

[0046] Simulation analysis module 3 is used to conduct stress analysis of crack-free thin-walled plate parts using the finite element analysis method, and obtain the second nominal stress of the thin-walled plate part at the test position under the working state;

[0047] The second analysis module 4 is used to perform stress analysis on the thin-walled plate with initial cracks at the test location using the finite element analysis method, to obtain the third nominal stress of the thin-walled plate with initial cracks in the working state, and to correct the third nominal stress by using the ratio of the first nominal stress to the second nominal stress as a correction coefficient, so as to obtain the corrected fourth nominal stress.

[0048] The crack propagation rate determination module 5 is used to calculate the stress intensity factor of the thin-walled plate with initial cracks using the Paris formula based on the fourth nominal stress, and to analyze and obtain the crack propagation rate of the thin-walled plate with initial cracks under working conditions based on the crack propagation curve of the thin-walled plate material.

[0049] Example 2

[0050] See Figure 1 An application of a method for analyzing crack propagation rate in high-temperature thin-walled plates includes:

[0051] Step 1: Obtain the load level of the thin-walled plate under working conditions, and conduct a life test on the thin-walled plate under the same load level until a crack appears at the test location of the thin-walled plate. Obtain the fatigue strip width at the initial position of the crack through fracture analysis.

[0052] 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, and fatigue cracks are obtained at the test location. The width of the fatigue band at the initial location of the crack is obtained through fracture surface analysis.

[0053] Step 2: Determine the initial crack propagation rate based on the fatigue band width. Based on the crack propagation curve of the thin-walled plate material, calculate the stress intensity factor at the initial crack propagation point, and use the Paris formula to calculate the first nominal stress at the initial crack propagation location.

[0054] In this embodiment, the initial crack propagation rate of the thin-walled plate can be obtained by measuring the fatigue band width in fracture analysis. ( This is a commonly used expression, in which The length of the crack. (Number of cycles). The initial crack propagation rate obtained through fracture surface analysis is the actual experimental result, which is more accurate than the crack propagation rate obtained through simulation methods. Stress intensity factor at initial crack propagation. ,in , These are the fitting parameters in the crack propagation curve of the thin-walled plate material. This represents the stress intensity factor at the crack location.

[0055] First nominal stress at the initial crack propagation location ,in For stress shape factor, The value range is 1 to 1.2. The first nominal stress at the initial crack propagation location, In fracture analysis, the distance from the fatigue stripe to the fatigue origin region is measured. The value of this distance should be determined in accordance with... The value corresponds to the position of the fatigue stripe from the fatigue source region.

[0056] Step 3: Perform stress analysis on the crack-free thin-walled plate using the finite element method to obtain the second nominal stress at the test location of the thin-walled plate under the working state. ;

[0057] Step 4: Conduct stress analysis on the thin-walled plate with initial cracks at the test location using the finite element method to obtain the third nominal stress of the thin-walled plate with initial cracks under working conditions. Using the first nominal stress With the second nominal stress The ratio of the third nominal stress is used as a correction factor. After making corrections, the corrected fourth nominal stress is obtained. ;

[0058] In this embodiment, the corrected fourth nominal stress is obtained. .

[0059] Step 5: Based on the fourth nominal stress, calculate the stress intensity factor of the thin-walled plate with initial crack using the Paris formula, and analyze the crack propagation rate of the thin-walled plate with initial crack under working conditions based on the crack propagation curve of the thin-walled plate material.

[0060] In this embodiment, the corrected fourth nominal stress Substituting into the Paris formula, the stress intensity factor of the thin-walled plate with initial cracks is calculated. , This is the initial crack length. Then, according to... Based on the fitting parameters in 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 calculated. .

[0061] Step 6: Based on the load on the bearing surface of the thin-walled plate, the tensile strength of the material of the thin-walled plate, and the dimensional parameters of the thin-walled plate, analyze and obtain the first critical crack length of the thin-walled plate; based on the fracture toughness of the material of the thin-walled plate and the corrected fourth nominal stress, analyze and obtain the second critical crack length of the thin-walled plate.

[0062] In this embodiment, the first critical crack length ,in 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 plates, For the tensile strength of thin-walled plate materials, For the load-bearing surface of thin-walled plate components, This can be obtained through finite element simulation analysis. The second critical crack length... ,in For stress shape factor, The value range is 1 to 1.2. This refers to the fracture toughness of thin-walled plate materials.

[0063] Step 7: Take the minimum value of the first critical crack length and the second critical crack length as the critical crack propagation length of the thin-walled plate with the initial crack. .

[0064] Based on the initial crack propagation rate, this embodiment combines the component characteristics of thin-walled plates and stress analysis results to obtain the crack propagation rate under different crack lengths, and then predicts the unstable propagation crack length, realizing accurate analysis of the acceptable critical crack length of thin-walled plates, and ensuring the test safety of the engine.

[0065] The above are merely 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 within the protection scope of the present invention.

Claims

1. A method for analyzing the crack propagation rate of high-temperature thin-walled plates, characterized in that, include: The load level of the thin-walled plate under working conditions is obtained, and a life test under the same load level is carried out on the thin-walled plate until a crack appears at the test location of the thin-walled plate. The fatigue strip width at the initial position of the crack is obtained through fracture analysis. The initial crack propagation rate is determined based on the fatigue band width. Based on the crack propagation curve of the thin-walled plate material, the stress intensity factor at the initial crack propagation is calculated, and the first nominal stress at the initial crack propagation location is calculated using the Paris formula. The finite element method was used to conduct stress analysis on a crack-free thin-walled plate to obtain the second nominal stress at the test location of the thin-walled plate under the working state. The finite element method is used to conduct stress analysis on a thin-walled plate with an initial crack at the test location. The third nominal stress of the thin-walled plate with an initial crack under working conditions is obtained. The ratio of the first nominal stress to the second nominal stress is used as a correction coefficient to correct the third nominal stress, and the corrected fourth nominal stress is obtained. Based on the fourth nominal stress, the stress intensity factor of the thin-walled plate with initial cracks is calculated using the Paris formula, and the crack propagation rate of the thin-walled plate with initial cracks under working conditions is analyzed based on the crack propagation curve of the thin-walled plate material.

2. The method for analyzing the crack propagation rate of high-temperature thin-walled plates according to claim 1, characterized in that, Stress intensity factor at initial crack propagation ,in , These are the fitting parameters in the crack propagation curve of the thin-walled plate material. The stress intensity factor at the crack location is... The initial crack propagation rate is denoted as .

3. The method for analyzing the crack propagation rate of high-temperature thin-walled plates according to claim 2, characterized in that, First nominal stress at the initial crack propagation location ,in For stress shape factor, The value range is 1 to 1.

2. The first nominal stress at the initial crack propagation location, This is used to measure the distance from the fatigue stripe to the fatigue origin region in fracture analysis.

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

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

6. The high-temperature thin-walled plate crack propagation rate analysis system according to claim 5, characterized in that, In the first analysis module, the stress intensity factor at the initial crack propagation stage ,in , These are the fitting parameters in the crack propagation curve of the thin-walled plate material. The stress intensity factor at the crack location is... The initial crack propagation rate is denoted as .

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

2. The first nominal stress at the initial crack propagation location, This is used to measure the distance from the fatigue stripe to the fatigue origin region in fracture analysis.

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

9. An application of a method for analyzing the crack propagation rate of high-temperature thin-walled plates, used to analyze and obtain the critical crack length of a thin-walled plate with an initial crack according to any one of claims 1-3, characterized in that, include: The first critical crack length of the thin-walled plate is obtained by analyzing the load on the bearing surface of the thin-walled plate, the tensile strength of the material of the thin-walled plate, and the dimensional parameters of the thin-walled plate; the second critical crack length of the thin-walled plate is obtained by analyzing the fracture toughness of the material of the thin-walled plate and the corrected 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 a thin-walled plate with an initial crack.

10. The application according to claim 9, characterized in that, First critical crack length ,in The width of the bearing surface of the thin-walled plate. The thickness of the bearing surface of thin-walled plates, For the tensile strength of thin-walled plate materials, For the load-bearing surface of thin-walled plate components, The second critical crack length can be obtained through finite element simulation analysis. ,in For stress shape factor, The value range is 1 to 1.

2. This refers to the fracture toughness of thin-walled plate materials.

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