Feature simulation part design method and engine disk test method

Abstract

The present invention discloses a method for designing a feature simulation component and a method for testing an engine disk. The method for designing the feature simulation component, where the feature simulation component is used for the crack propagation test of the engine disk, includes: S1. constructing a three-dimensional geometric model based on the actual component of the engine disk; S2. establishing a finite element analysis model based on the three-dimensional geometric model and material parameters of the actual component of the engine disk; S3. designing the simulation component to have a stress concentration simulation structure and a stress gradient distribution simulation structure, and determining the initial basic dimensions of the simulation component; S4. performing finite element simulation analysis; S5. judging whether the stress test data of the simulation component is consistent with that of the actual component. If so, the design of the simulation component is completed. If not, adjust the dimensions of the stress concentration simulation structure of the simulation component and / or adjust the dimensions of the stress gradient distribution simulation structure of the simulation component, and repeat steps S4 - S5 until the stress test data of the simulation component is consistent or tends to be consistent with that of the actual component.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engine performance testing, and in particular, to a method for designing a characteristic simulation part. In addition, the present invention also relates to an engine disk test method including the above-mentioned method for designing a characteristic simulation part. Background Art

[0002] Damage tolerance design needs to be carried out for engine disks, that is, to calculate the crack propagation life of the disks. In order to verify the analysis results, verification tests need to be carried out. However, aero-engine disks are costly, and it is very expensive to conduct crack propagation tests using actual disks or simulation disks close to the sub-structure of the disks. For the initial stage of design, more economical simulation parts need to be designed based on the characteristics of key parts of the disks to conduct fatigue life tests to meet the requirements of analysis method verification and design iteration.

[0003] However, it is found in actual research that appropriate simulation part structures and parameters need to be found to enable them to accurately simulate the stress gradient characteristics of actual disks. However, traditional characteristic simulation parts with circular holes have many problems and cannot well meet actual needs. For example, in the technical solution with the patent number: CN202311219448.8, a design method for a simulation part for predicting the low-cycle fatigue performance of an engine disk is disclosed. The structural characteristics are equivalently simplified, and the equivalently simplified structural characteristics are used as the gauge section. By adjusting the relative position relationship (parallel offset position and distance) between the clamping section and the gauge section, the stress gradient and fatigue failure characteristics of the simulation part are made consistent with those of the workpiece to be simulated. The equivalent loading position and equivalent load of the simulation part are adjusted through finite element analysis. The structural adjustment is relatively fixed, and the consistency between the simulation result and the stress test data of the actual component is weak. Another example is the technical solution with the patent number: CN201810797101.4, which discloses a design method for a simulation part for simulating the crack propagation characteristics of the central hole of a centrifugal impeller. The geometric characteristics and working conditions of the centrifugal impeller are considered, and the stress concentration and stress gradient in the actual structure are simulated through finite element analysis. However, this method may have limitations when simulating complex stress states. Due to the simplification of the model, it may not be able to fully capture the stress gradient characteristics of all local stress concentration areas in the actual disk, especially when simulating actual load conditions with high complexity. This kind of simplification may lead to deviations between the simulation results and the actual situation in some cases. On the other hand, this design method considers the circumferential stress equivalence, while the crack propagation driving force is the first principal stress. When applied to crack propagation tests, the test results of the simulation part will be inconsistent with the test results of the actual disk. Summary of the Invention

[0004] The present invention provides a method for designing a feature simulation component and a method for testing an engine disk, so as to solve the technical problems in the prior art that the design adjustment flexibility of the simulation component for the crack propagation simulation test of the engine disk is poor, the adjustment range is limited, and the actual simulation result is difficult to accurately reflect the real test result.

[0005] According to one aspect of the present invention, there is provided a method for designing a feature simulation component, where the feature simulation component is used for the crack propagation test of an engine disk, and the method for designing the feature simulation component includes:

[0006] S1. Construct a three-dimensional geometric model based on the actual geometric configuration of the hub part of the engine disk, and obtain material parameters;

[0007] S2. Establish a multi-physics field finite element analysis model including centrifugal load and temperature load based on the three-dimensional geometric model and material parameters of the actual component of the engine disk;

[0008] S3. Design a simulation component, with the equivalent of the crack propagation driving force as the goal and based on the equality of the maximum first principal stress and the equality of the first principal stress gradient as the optimization principle, so that the simulation component has a stress concentration simulation structure, a stress gradient distribution simulation structure, and connection structures arranged at both ends of the simulation component. The stress concentration simulation structure includes an elliptical hole structure formed at the middle position of the simulation component, and the stress gradient distribution simulation structure includes arc structures formed on both sides of the middle of the simulation component, and determine the initial basic dimensions of the simulation component;

[0009] S4. Conduct finite element simulation analysis to analyze the stress distribution, and respectively obtain the first principal stress gradient data at the first preset position and the second preset position from the stress concentration simulation structure;

[0010] S5. Perform iterative optimization based on the gradient sensitive area. If the deviation of the first principal stress gradient data at the first preset position is greater than the preset percentage, adjust the aspect ratio of the elliptical hole structure. If the deviation of the first principal stress gradient data at the second preset position is greater than the preset percentage, adjust the radius of the arc structure. If the deviation of the first principal stress gradient data in the entire region is less than or equal to the preset percentage, complete the iterative optimization.

[0011] As a further improvement of the above technical solution, step S1 includes: using computer-aided design software to construct a three-dimensional geometric model of the actual component according to the accurate dimensions and shape of the actual component as the basic framework for analysis and simulation; the material parameters include density, elastic modulus, and Poisson's ratio.

[0012] As a further improvement of the above technical solution, step S2 further includes: setting boundary conditions and load conditions based on reflecting the working state of the actual component, and setting typical conditions to cover various stress states in the working state of the actual component.

[0013] As a further improvement of the above technical solution, the connection structure includes connection holes formed at both ends of the simulation part, and the connection holes are used to be connected to the fixture of the test equipment through a pin shaft.

[0014] As a further improvement of the above technical solution, a transition structure is provided between the connection structure and the stress concentration simulation structure.

[0015] According to another aspect of the present invention, an engine disk test method is further provided, which includes the above-mentioned characteristic simulation part design method, and the test method includes:

[0016] A1. Install the simulation part on the fatigue testing machine through the connection structure, and apply a cyclic tensile force equivalent to that of the actual disk.

[0017] A2. Monitor the crack initiation and propagation behavior based on the DIC technology.

[0018] A3. Evaluate the crack propagation life of the actual disk according to the test results of the simulation part.

[0019] As a further improvement of the above technical solution, step A2 includes: using the relative deformation amplitude of the simulation part under the action of a high-low cycle random combined load spectrum to judge the moment when cracks may initiate.

[0020] As a further improvement of the above technical solution, step A2 includes: the number of DIC measurement points in the test is greater than or equal to 10.

[0021] The present invention has the following beneficial effects:

[0022] This design method first constructs a three-dimensional geometric model of the actual component and collects various performance parameters of the actual component material, and establishes a finite element static analysis model through finite element analysis software, which discretizes the actual component into a finite number of units, and solves the stress-strain state of each unit under specific working conditions through mathematical methods, thereby obtaining the stress distribution state of the entire component, and designs the simulation part with the goal of equivalent crack extension driving force and based on the optimization principle of equal maximum first principal stress and equal first principal stress gradient, so that the simulation part has an elliptical hole structure formed in the middle of the simulation part as a stress concentration simulation structure, and arc structures formed on both sides of the middle of the simulation part as stress gradient distribution simulation structures, and utilizes the stress concentration characteristics of the elliptical shape when subjected to force to simulate the stress concentration area in the actual component, such as the center hole of the wheel or other local stress concentration parts, and the outer arc structure is located at the periphery of the elliptical hole structure, and effectively disperses stress through its smoothly transitioned shape, simulating the stress gradient change of the actual component, so that the stress distribution of the simulation part is closer to the actual situation; by performing finite element analysis on the simulation part The simulation analysis is used to analyze the stress distribution, and the first principal stress gradient data at two different preset positions away from the elliptical hole structure are obtained respectively. Then, the aspect ratio of the elliptical hole or the radius of the arc structure can be adjusted separately according to the different stress gradient sensitive areas for iterative optimization. If the deviation of the first principal stress gradient data at the first preset position in the simulation result is greater than the preset percentage, the aspect ratio of the elliptical hole is adjusted. If the deviation of the first principal stress gradient data at the second preset position is greater than the preset percentage, the radius of the arc structure is adjusted, and the simulation analysis is performed again. This process is repeated to iteratively optimize the structural parameters of the simulation part. When the deviation of the first principal stress gradient data in the entire area is less than or equal to the preset percentage, the iterative optimization is terminated, and the design of the simulation part is completed. The present design method simulates the stress concentration area and stress gradient of the actual component more accurately, and matches the stress gradient of the simulation part with the actual wheel disc height by optimizing the size of the stress concentration simulation structure and the size of the stress gradient distribution simulation structure of the simulation part, and has higher simulation accuracy, thereby avoiding the problem of inconsistency between the simulation part test results and the real disc test results due to incomplete stress considerations.Meanwhile, this design method is more flexible. It can adjust the stress concentration simulation structure and the stress gradient distribution simulation structure respectively according to different simulation requirements for multiple combinations, so as to achieve accurate simulation of the characteristics of actual components. Through finite element analysis, the simulation results are compared and verified with the stress test data of actual components to further ensure the accuracy of the simulation. Based on the calculation of the actual model stress of the actual model construction as the simulation basis and multiple simulation adjustments to optimize the parameters of the simulation parts, the effectiveness is finally verified. The overall process is streamlined and closely related, forming a complete closed loop, ensuring the scientificity and accuracy of the simulation part design. The interference and influence degree between the stress concentration simulation structure and the stress gradient distribution simulation structure of this design method is low. Furthermore, it can be adjusted separately based on the parameter decoupling method, and based on this, the number of design iterations can be compressed to no more than 4 rounds, greatly improving the design optimization efficiency while improving the simulation accuracy.

[0023] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The following will refer to the drawings to further elaborate on the present invention in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0025] Figure 1 is a flowchart of the design method of the feature simulation part of the preferred embodiment of the present invention;

[0026] Figure 2 is a schematic structural diagram of the feature simulation part of the preferred embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of the first principal stress gradient data of the actual component in the first embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of the structure and stress distribution of the feature simulation part in the first embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of the stress distribution of the elliptical hole structure of the feature simulation part in the first embodiment of the present invention;

[0030] Figure 6 is the first principal stress gradient at 5 mm away from the hole edge under the first preset condition in the first embodiment of the present invention;

[0031] Figure 7 is the first principal stress gradient at 0.5 mm away from the hole edge under the first preset condition in the first embodiment of the present invention;

[0032] Figure 8is the first principal stress gradient at 5 mm away from the hole edge under the second preset condition in Embodiment 1 of the present invention;

[0033] Figure 9 is the first principal stress gradient at 0.5 mm away from the hole edge under the second preset condition in Embodiment 1 of the present invention;

[0034] Figure 10 is the first principal stress gradient at 5 mm away from the hole edge under the third preset condition in Embodiment 1 of the present invention;

[0035] Figure 11 is the first principal stress gradient at 0.5 mm away from the hole edge under the third preset condition in Embodiment 1 of the present invention;

[0036] Figure 12 is the first principal stress gradient at 5 mm away from the hole edge under the fourth preset condition in Embodiment 1 of the present invention;

[0037] Figure 13 is the first principal stress gradient at 0.5 mm away from the hole edge under the fourth preset condition in Embodiment 1 of the present invention;

[0038] Figure 14 is the first principal stress distribution nephogram of the feature simulation part structure in Comparative Example 1 of the present invention;

[0039] Figure 15 is the stress distribution nephogram of the area near the circular hole in Comparative Example 1 of the present invention;

[0040] Figure 16 is the first principal stress gradient at 5 mm away from the hole edge when analyzing the influence of the circular hole diameter in Comparative Example 1 of the present invention;

[0041] Figure 17 is the first principal stress gradient at 0.5 mm away from the hole edge when analyzing the influence of the circular hole diameter in Comparative Example 1 of the present invention;

[0042] Figure 18 is the first principal stress gradient at 5 mm away from the hole edge when analyzing the influence of the outer arc in Comparative Example 1 of the present invention;

[0043] Figure 19 is the first principal stress gradient at 0.5 mm away from the hole edge when analyzing the influence of the outer arc in Comparative Example 1 of the present invention;

[0044] Figure 20 is the schematic diagram for analyzing the influence of the notch radius on the stress gradient in Comparative Example 1 of the present invention;

[0045] Figure 21 is the schematic diagram for analyzing the influence of the notch net cross-sectional width on the stress gradient in Comparative Example 1 of the present invention;

[0046] Figure 22It is a schematic structural diagram of the simulation part in Comparative Example 1 of the present invention.

[0047] Legend:

[0048] 1. Stress concentration simulation structure; 2. Stress gradient distribution simulation structure; 3. Connection structure; 4. Transition structure. Specific implementation mode

[0049] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways defined and covered by the following.

[0050] Figure 1 It is a flowchart of the design method of the feature simulation part of the preferred embodiment of the present invention; Figure 2 It is a schematic structural diagram of the feature simulation part of the preferred embodiment of the present invention; Figure 3 It is a schematic diagram of the first principal stress gradient data of the actual component in Embodiment 1 of the present invention; Figure 4 It is a schematic diagram of the structure and stress distribution of the feature simulation part in Embodiment 1 of the present invention; Figure 5 It is a schematic diagram of the stress distribution of the elliptical hole structure of the feature simulation part in Embodiment 1 of the present invention; Figure 6 It is the first principal stress gradient at a distance of 5 mm from the hole edge under the first preset condition in Embodiment 1 of the present invention; Figure 7 It is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the first preset condition in Embodiment 1 of the present invention; Figure 8 It is the first principal stress gradient at a distance of 5 mm from the hole edge under the second preset condition in Embodiment 1 of the present invention; Figure 9 It is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the second preset condition in Embodiment 1 of the present invention; Figure 10 It is the first principal stress gradient at a distance of 5 mm from the hole edge under the third preset condition in Embodiment 1 of the present invention; Figure 11 It is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the third preset condition in Embodiment 1 of the present invention; Figure 12 It is the first principal stress gradient at a distance of 5 mm from the hole edge under the fourth preset condition in Embodiment 1 of the present invention; Figure 13 It is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the fourth preset condition in Embodiment 1 of the present invention.

[0051] As Figure 1 and Figure 2 shown, for the feature simulation part design method of this embodiment, the feature simulation part is used for the crack propagation test of the engine disk, and the feature simulation part design method includes:

[0052] S1. Construct a three-dimensional geometric model based on the actual geometric configuration of the engine disk hub part and obtain material parameters;

[0053] S2. Establish a multi - physical - field finite - element analysis model including centrifugal load and temperature load based on the three - dimensional geometric model and material parameters of the actual components of the engine disk.

[0054] S3. Design a simulation part. With the equivalent of the crack - propagation driving force as the goal and based on the principles of equal maximum first principal stress and equal first principal stress gradient for optimization, make the simulation part have a stress - concentration simulation structure 1, a stress - gradient distribution simulation structure 2, and a connection structure 3 arranged at both ends of the simulation part. The stress - concentration simulation structure 1 includes an elliptical - hole structure formed at the middle position of the simulation part. The stress - gradient distribution simulation structure 2 includes arc structures formed on both sides of the middle of the simulation part. Determine the initial basic dimensions of the simulation part.

[0055] S4. Conduct finite - element simulation analysis to analyze the stress distribution, and respectively obtain the first principal stress gradient data at the first preset position and the second preset position from the stress - concentration simulation structure 1.

[0056] S5. Conduct iterative optimization based on the gradient - sensitive area. If the deviation of the first principal stress gradient data at the first preset position is greater than the preset percentage, adjust the aspect ratio of the elliptical - hole structure. If the deviation of the first principal stress gradient data at the second preset position is greater than the preset percentage, adjust the radius of the arc structure. If the deviation of the first principal stress gradient data in the whole region is less than or equal to the preset percentage, complete the iterative optimization.

[0057] Among them, the connection structure 3 is used to connect with the test equipment to transfer loads, and the specific structure can be designed according to test requirements. The first preset position is selected as the front - end position close to the main area affecting the crack - propagation life. The second preset position is selected as the rear - end position close to the main area affecting the crack - propagation life.

[0058] In a specific embodiment, the first preset position is 0.5 mm away from the elliptical - hole structure, the second preset position is 5 mm away from the elliptical - hole structure, and the preset percentage is preferably 5%, which can also be adjusted according to actual needs. It should be noted that in step S5, the adjustment gradient of the aspect ratio of the elliptical - hole structure is less than or equal to 0.01, and the adjustment gradient of the radius of the arc structure is less than or equal to 50 mm. Among them, for every 0.01 increase in the aspect ratio of the elliptical - hole structure, the gradient at 0.5 mm from the hole edge decreases by 5% - 8%. For every 50 - mm decrease in the radius of the arc structure, the gradient attenuation rate at 5 mm increases by 10% - 15%.

[0059] It should be noted that during the test process before actual design, analyze the influence law of the elliptical - hole - structure characteristics on the stress gradient of the characteristic simulation part. The structure of the characteristic simulation part with the elliptical - hole structure and its stress distribution are as Figure 3As shown. The results show that the characteristic simulation components with aspect ratios of 0.125 and 0.1 both show a trend that as the radius of the arc structure on the outside decreases, the rate of decrease in the stress amplitude slows down. When the aspect ratio is fixed, increasing the height of the elliptical hole structure also shows a trend that the rate of decrease in the stress amplitude slows down. For all test conditions, whether the aspect ratio is 0.125 or 0.1, the smaller the radius of the outer arc, the slower the rate of decrease in the stress amplitude. That is, the change amplitude of the radius of the arc structure is positively correlated with the change amplitude of the stress gradient, which also confirms that the radius of the outer arc is the decisive factor controlling the change rate of the stress gradient.

[0060] It can be understood that in this design method, first, a three-dimensional geometric model of the actual component is constructed and various performance parameters of the actual component material are collected and obtained. A finite element static analysis model is established through finite element analysis software. It discretizes the actual component into a finite number of elements, and solves the stress and strain states of each element under specific working conditions through mathematical methods, so as to obtain the stress distribution state of the entire component. With the equivalent of the crack propagation driving force as the goal and based on the equal maximum first principal stress and the equal first principal stress gradient as the optimization principle, a simulated component is designed. The simulated component has an elliptical hole structure formed in the middle position of the simulated component as the stress concentration simulation structure 1, and arc structures formed on both sides of the middle of the simulated component as the stress gradient distribution simulation structure 2. By using the characteristic of stress concentration when the ellipse is stressed, the stress concentration area in the actual component, such as the center hole of the disk or other local stress concentration parts, is simulated. The outer arc structure is located around the elliptical hole structure, and through its smoothly transitioning shape, the stress is effectively dispersed, simulating the stress gradient change of the actual component, making the stress distribution of the simulated component closer to the real situation; through finite element simulation analysis of the simulated component to analyze the stress distribution, the first principal stress gradient data at two different preset positions from the elliptical hole structure are respectively obtained. Furthermore, the aspect ratio of the elliptical hole or the radius of the arc structure can be adjusted separately for iterative optimization according to the different stress gradient sensitive areas. If the deviation of the first principal stress gradient data at the first preset position in the simulation result is greater than the preset percentage, adjust the aspect ratio of the elliptical hole. If the deviation of the first principal stress gradient data at the second preset position is greater than the preset percentage, adjust the radius of the arc structure, and then perform simulation analysis again. Repeat this process to iteratively optimize the structural parameters of the simulated component. When the deviation of the first principal stress gradient data in the entire region is less than or equal to the preset percentage, end the iterative optimization, that is, complete the design of the simulated component; this design method more accurately simulates the stress concentration area and stress gradient of the actual component, and matches the stress gradient of the simulated component with the actual disk height by optimizing the size of the stress concentration simulation structure 1 and the size of the stress gradient distribution simulation structure 2 of the simulated component, with higher simulation accuracy, avoiding the problem that the test results of the simulated component are inconsistent with the test results of the real disk due to incomplete stress consideration;Meanwhile, this design method is more flexible. It can adjust the stress concentration simulation structure 1 and the stress gradient distribution simulation structure 2 respectively according to different simulation requirements for multiple combinations, so as to achieve accurate simulation of the characteristics of actual components. By comparing the simulation results with the stress test data of actual components through finite element analysis for verification, the accuracy of the simulation is further ensured. Based on the actual model construction, the stress of the actual model is calculated as the simulation basis, and the parameters of the simulation parts are adjusted and optimized through multiple simulations. Finally, its effectiveness is verified. The overall process is streamlined and closely related, forming a complete closed loop, ensuring the scientificity and accuracy of the simulation part design. The interference and influence degree between the stress concentration simulation structure 1 and the stress gradient distribution simulation structure of this design method is low. Therefore, they can be adjusted separately based on the parameter decoupling method, and based on this, the number of design iterations can be compressed to no more than 4 rounds, greatly improving the design optimization efficiency while improving the simulation accuracy.

[0061] Further, step S1 includes: using computer-aided design software to construct a three-dimensional geometric model of the actual component according to the precise dimensions and shape of the actual component, which serves as the basic framework for analysis and simulation. Specifically, using professional computer-aided design software such as SolidWorks and CATIA, construct its three-dimensional geometric model according to the precise dimensions, shape and other parameters of the actual component. This model will serve as the basic framework for subsequent analysis and simulation, accurately presenting the geometric shape of the actual component and providing a prerequisite for accurately simulating the stress distribution. It should be understood that for complex components such as aeroengine disks, the model needs to carefully depict its features such as contours, hole positions, and channels to ensure high consistency with the actual component. Material parameters include density, elastic modulus, and Poisson's ratio. Specifically, collect various performance parameters of the material of the actual component, including density, elastic modulus, Poisson's ratio, etc. These parameters are key indicators for describing the mechanical behavior of materials and are crucial for accurately calculating and analyzing the stress and strain response of components under stress. For example, for TC4 (special) alloy, its unique material characteristic parameters will directly affect the stress distribution law of the disk under different working conditions. Accurately obtaining these parameters is the basis for subsequent accurate simulation.

[0062] Further, step S2 also includes: setting boundary conditions and load conditions based on reflecting the working state of the actual component, and setting typical conditions to cover various stress states under the working state of the actual component. Specifically, during the model establishment process, parameters such as boundary conditions and load conditions need to be reasonably set to ensure that the simulation results can truly reflect the working state of the actual component. The typical conditions cover various stress states that the component may encounter during actual operation, such as the stress conditions of the engine disk under high-speed rotation and temperature change. Through precise calculation, obtain the distribution law of stress at different positions of the component and the gradient information of stress change with position, providing a key basis for the design of the simulation part.

[0063] It is understandable that the central circular hole structure of the conventional simulation part is improved to an elliptical hole structure in this design method to simulate the stress concentration area, and an arc structure is designed to simulate the stress gradient distribution, fully considering and simulating the characteristics of the first principal stress gradient, providing a more reliable test model for the crack propagation research of the key parts of the disk, and helping to improve the prediction accuracy of the crack propagation performance of components such as disks under the actual working environment; on the other hand, this simulation part has a better simulation effect on complex components. The simulation of the stress concentration area of the elliptical hole structure and the simulation of the stress gradient distribution of the arc structure can better adapt to the complex stress state, accurately simulate the stress gradient characteristics of the local stress concentration area, overcome the limitations of traditional simulation parts in the simulation of complex components, and have high popularization prospects and practical application values.

[0064] In some embodiments, the connecting structure 3 includes connecting holes opened at both ends of the simulation part, and the connecting holes are used to connect with the fixture of the test equipment through a pin shaft.

[0065] In some embodiments, a transition structure 4 is arranged between the connecting structure 3 and the stress concentration simulation structure 1 to make a smooth connection between the two, so as to ensure the structural continuity, enable the load to be transmitted smoothly, and avoid simulation errors caused by stress concentration or unsmooth transmission.

[0066] On the other hand, this preferred embodiment also provides an engine disk test method, which includes the above-mentioned characteristic simulation part design method. The test method includes:

[0067] A1. Install the simulation part on the fatigue testing machine through the connecting structure 3, and apply a cyclic tensile force equivalent to the actual disk; it is realized based on the existing method and will not be elaborated too much; it should be noted that the test piece can be pretreated before the test, and a high-contrast random gray distribution image can be obtained by painting the test piece, that is, a random pattern is arranged by adding speckles so that the tested test piece can be clearly imaged and recognized in the camera;

[0068] A2. Monitor the crack initiation and propagation behavior based on the DIC technology;

[0069] Preferably, in the crack initiation stage, step A2 includes: using the relative deformation amplitude of the simulation part under the action of a high-low cycle random combined load spectrum to judge the possible moment of crack initiation; using a fatigue testing machine to monitor the relative displacement change trend of the characteristic simulation part during the crack propagation test, and finding the position of the starting cycle number in the crack initiation stage. In the early stage, through a preliminary test, it is found that during the crack initiation and propagation stages of the characteristic simulation part, starting from about 5400 load cycles, the relative displacement of the simulation part significantly increases. Continuing the fatigue test until about 5800 times, the simulation part fractures. Therefore, in order to save the DIC sampling time and improve the test and subsequent analysis efficiency, use the relative deformation amplitude of the simulation part under the action of a high-low cycle random combined load spectrum to judge the possible moment of crack initiation. Then, start the DIC test and analysis system to test the transient load crack propagation characteristics and development trends of the structurally weak areas of the simulation part;

[0070] Preferably, in the crack propagation stage, step A2 includes: the number of DIC measurement points in the test is greater than or equal to 10; specifically, the digital image correlation (DIC) method is used to measure displacement. Its basic technology is: an initial reference image is adopted, and the subsequent images of the deformed object are correlated with the reference image to find the position of the maximum correlation between the two images. The corresponding translation can be used as a measure of displacement. The principle of using the DIC method to measure the crack opening force is that as the load P in the form of a triangular wave acts, the crack tip opening displacement (COD) stabilizes near the minimum value within a certain range near the minimum load, corresponding to the crack closed state. As the load P increases, the COD first remains at the minimum value, and when the load P reaches a certain critical value, the COD begins to increase, corresponding to the crack opening. Therefore, the load corresponding to the end point of the line segment corresponding to the minimum value is the load required for crack opening, denoted as Pop. The test interval determines the visualization degree of crack propagation of the test piece. Therefore, the DIC test interval should be as short as possible to obtain enough data points, and the number of DIC measurement points in the subsequent test is arranged in more than 10;

[0071] A3. Evaluate the crack propagation life of the actual disk according to the test results of the simulation part.

[0072] Example 1

[0073] This example applies the characteristic simulation part design method of the above preferred example. For the static analysis of the TC4 (special) alloy disk and the stress gradient of the assessment part, the first principal stress gradient data of the disk assessment area (maximum distance 15.92 mm) is extracted and normalized. The results are as Figure 3 shown.

[0074] In this embodiment, the first preset position and the second preset position are taken as 0.5 mm and 5 mm respectively. Keeping the length of the elliptical hole unchanged at 8 mm, the height of the hole is changed to analyze the influence law of the elliptical height on the stress gradient. The working conditions of the elliptical hole height are 4 mm, 2 mm, 1 mm, and 0.5 mm respectively. It can be seen that the smaller the height of the elliptical hole, the slower the decline rate of the stress gradient at the hole edge; when the elliptical hole has a length of 8 mm and a height of 1 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual stress level of the compressor disk.

[0075] In this embodiment, the first preset position and the second preset position are taken as 0.5 mm and 5 mm respectively. Keeping the height of the elliptical hole unchanged at 1 mm, the length of the hole is changed to analyze the influence law of the elliptical length on the stress gradient. The working conditions of the elliptical hole length are 10 mm, 8 mm, 6 mm, and 4 mm respectively. It can be seen that the larger the length of the elliptical hole, the slower the decline rate of the stress gradient at the hole edge; when the elliptical hole has a height of 1 mm and a length of 10 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual stress level of the compressor disk; for further verification, keeping the height of the elliptical hole unchanged at 1 mm, the length of the hole is continuously increased and the stress gradient is analyzed. The working conditions of the elliptical hole length are 15 mm, 12 mm, 10 mm, and 8 mm respectively. It can be seen that the larger the length of the elliptical hole, the slower the decline rate of the stress gradient at the hole edge; when the elliptical hole has a height of 1 mm and a length of 12 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual stress level of the compressor disk.

[0076] In this embodiment, the first preset position and the second preset position are taken as 0.5 mm and 5 mm respectively. Through finite element analysis software for simulation, the dimensions of the elliptical hole structure and the radius of the arc structure on the outside are optimized to achieve a high degree of matching with the stress distribution of the actual component. Innovatively, the circular hole notch in the middle of the characteristic simulation part is adjusted to an elliptical hole structure, and the influence law of the elliptical hole notch feature on the stress gradient of the characteristic simulation part is analyzed. The structure of the characteristic simulation part with the elliptical hole structure and its stress distribution are as Figure 4 and Figure 5 shown. The results show that for the characteristic simulation parts with aspect ratios of 0.125 and 0.1, the trend that the stress amplitude decreases more slowly as the outer arc radius decreases is shown. When the aspect ratio is fixed, increasing the height of the elliptical hole structure (for example, from 1 mm to 1.5 mm) also shows the trend that the stress amplitude decreases more slowly. For all test conditions, whether the aspect ratio is 0.125 or 0.1, the smaller the radius of the arc structure, the slower the stress amplitude decreases. This finding confirms that the outer arc radius is the decisive factor controlling the change rate of the stress gradient. When the aspect ratio of the elliptical hole structure is 0.125 and the length is 8 mm, and the outer arc radii of the elliptical hole structure are ∞ (straight line), 500 mm, 250 mm, and 100 mm respectively, the first principal stress gradient 5 mm away from the edge of the elliptical hole structure is as Figure 6As shown, the first principal stress gradient at a distance of 0.5 mm from the hole edge is as Figure 7 shown, and it can be seen that:

[0077] 1) The smaller the radian of the outer arc structure of the elliptical hole structure, the slower the decrease rate of the stress gradient at the hole edge;

[0078] 2) When the outer radian is 100 mm, the stress gradient at the hole edge of the characteristic simulation part locally exceeds the actual disk stress level.

[0079] When the aspect ratio of the elliptical hole structure is 0.1 and the length is 10 mm, and the outer radian radii of the elliptical hole structure are ∞ (straight line), 500 mm, 250 mm, and 100 mm respectively, the first principal stress gradient at a distance of 5 mm from the hole edge is as Figure 8 shown, and the first principal stress gradient at a distance of 0.5 mm from the edge of the elliptical hole structure is as Figure 9 shown, and it can be seen that:

[0080] 1) The smaller the radian of the outer arc structure of the elliptical hole structure, the slower the decrease rate of the stress gradient at the hole edge;

[0081] 2) When the outer radian is 250 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual disk stress level.

[0082] When the aspect ratio of the elliptical hole structure is 0.1 and the length is 15 mm, and the outer radian radii of the elliptical hole structure are ∞ (straight line), 500 mm, 250 mm, and 100 mm respectively, the first principal stress gradient at a distance of 5 mm from the hole edge is as Figure 10 shown, and the first principal stress gradient at a distance of 0.5 mm from the hole edge is as Figure 11 shown, and it can be seen that:

[0083] 1) The smaller the radian of the outer arc structure of the elliptical hole structure, the slower the decrease rate of the stress gradient at the hole edge;

[0084] 2) When the outer radian is 250 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual disk stress level.

[0085] The finally determined structural dimensions of the simulation part and the designed parameters of the characteristic simulation part are as follows: the length of the elliptical hole is 15 mm, the aspect ratio is 0.1, and the radian of the outer arc structure of the elliptical hole structure is 225 mm. At this time, the first principal stress gradient at a distance of 5 mm from the hole edge of the characteristic simulation part is as Figure 12 shown, and the first principal stress gradient at a distance of 0.5 mm from the hole edge is as Figure 13 shown. It can be seen that the stress gradient of the designed characteristic simulation part is relatively close to the actual disk stress level and can be used for the crack propagation test of the disk characteristic simulation part.

[0086] Table 1 Influence of elliptical hole size on the stress gradient of the characteristic simulation part

[0087]

[0088] Combining the above analysis, the content of Table 1 is obtained. Based on the comprehensive above analysis results, the structural dimensions of the simulation part are finally determined. The parameters of the notch of the designed feature simulation part are: the length of the elliptical hole is 15 mm, the aspect ratio of length to height is 0.1, and the outer arc of the notch structure is 225 mm. At this time, the first principal stress gradient of the feature simulation part at different positions from the hole edge (such as 5 mm and 0.5 mm) is extremely close to the actual stress level of the disk, indicating that this simulation part can accurately simulate the stress distribution characteristics of the actual disk and can be used for the crack propagation test of the disk feature simulation part, providing a reliable test model for the crack propagation research of components such as disks. Moreover, based on the actual implementation effect of this embodiment, the adjustment step size in step S5 (that is, the adjustment step size of the circular arc structure is 50 mm, and the adjustment step size of the aspect ratio of the length to height of the elliptical hole structure is 0.01) can complete the optimization design of the simulation part within four rounds of iterative optimization, and the design efficiency is greatly improved.

[0089] Moreover, through experimental verification, the stress gradient conditions of the simulation part under variable amplitude loading conditions measured by the subsequent DIC strain and measurement system are basically the same.

[0090] Comparative Example 1

[0091] In this comparative example, referring to Figure 14 and Figure 15 , the middle part of the simulation part is a circular hole structure. Keeping the structural dimensions of the feature simulation part unchanged, the diameter of the circular hole is changed to analyze the influence law on the stress gradient; under the working conditions where the diameter of the circular hole is 0.5 mm, 1 mm, 2 mm, and 4 mm respectively, referring to Figure 16 and Figure 17 , it can be seen that as the diameter of the circular hole increases, the decrease rate of the stress gradient at the hole edge becomes slower, and the stress gradient decrease rate of the feature simulation part with a circular hole is much higher than the stress level of the actual compressor disk. The requirements cannot be met through this feature simulation part structure; referring to Figure 18 and Figure 19 , the stress gradient decrease rate at the hole edge of the feature simulation part with a circular hole notch is too fast. A certain arc is introduced on the outside of the notch structure to observe the influence law of the outer arc on the stress gradient at the hole edge. Keeping the diameter of the circular hole notch of the feature simulation part unchanged at 2 mm, the stress gradient at the hole edge under the working conditions where the diameter of the outer arc is ∞, 500 mm, 250 mm, and 50 mm respectively is analyzed. It can be seen that as the radius of the outer arc becomes larger, the stress gradient decrease rate at the hole edge becomes slower, but this influence is very small, which is consistent with the conclusion obtained in the reference "Wei Dasheng et al., Design method and experimental verification of the simulation test piece for the central hole of the aero-engine disk, Journal of Aerospace Power". That is, the stress gradient of the circumferential stress along the radial direction at the edge of the central hole of the disk is too small, referring to Figure 20 and Figure 21, it is impossible to obtain a comparable stress gradient by changing the notch geometry. To characterize the stress gradient characteristics caused by the structure at the center hole of the disk, the notch geometry of the stress gradient characteristic simulation part at the disk center directly uses the curvature radius at the disk center, only considering the consistency of the stress amplitude while ignoring the consistency of the stress gradient. Refer to Figure 22 , finally, no matter how the size of the simulation part with a circular hole feature is changed for the designed stress gradient characteristic simulation part at the disk center, the stress gradient level at the hole edge cannot meet the stress gradient characteristics of the actual compressor disk.

[0092] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0093] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0094] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for designing a characteristic simulation part, wherein the characteristic simulation part is used for crack growth test of an engine wheel disc, characterized in that: The characteristic simulation part design method comprises: S1. Construct a three-dimensional geometric model based on the actual geometric configuration of the wheel center of the engine wheel to obtain material parameters; S2. Establish a multi-physics finite element analysis model including centrifugal load and temperature load based on the three-dimensional geometric model and material parameters of the actual components of the engine wheel; S3. Design a simulation component, aiming at the equivalence of crack propagation driving force and based on the optimization principle of equal maximum first principal stress and equal first principal stress gradient, so that the simulation component has a stress concentration simulation structure (1), a stress gradient distribution simulation structure (2) and a connection structure (3) arranged at both ends of the simulation component, wherein the stress concentration simulation structure (1) includes an elliptical hole structure formed in the middle of the simulation component, and the stress gradient distribution simulation structure (2) includes arc structures formed on both sides of the middle of the simulation component, and the initial basic size of the simulation component is determined; S4. Perform finite element simulation analysis to analyze stress distribution, and obtain first principal stress gradient data from a first preset position and a second preset position of the stress concentration simulation structure (1); S5. Perform iterative optimization based on the gradient sensitive area. If the first principal stress gradient data deviation at the first preset position is greater than the preset percentage, adjust the aspect ratio of the elliptical hole structure. If the first principal stress gradient data deviation at the second preset position is greater than the preset percentage, adjust the radius of the arc structure. If the first principal stress gradient data deviation in the entire area is less than or equal to the preset percentage, complete the iterative optimization.

2. The characteristic simulation component design method according to claim 1, characterized in that: Step S1 includes: using computer-aided design software to construct a three-dimensional geometric model of the actual component according to the precise size and shape of the actual component as a basic framework for analysis and simulation; material parameters include density, elastic modulus, and Poisson's ratio.

3. The characteristic simulation component design method according to claim 1, characterized in that: Step S2 also includes: setting boundary conditions and load conditions based on the working state of the actual component, and setting typical conditions to cover various stress states under the working state of the actual component.

4. The characteristic simulation component design method according to claim 1, characterized in that: The connection structure (3) comprises connection holes opened at both ends of the simulation part, and the connection holes are used to connect with the clamp of the test equipment through a pin shaft.

5. The characteristic simulation component design method according to claim 1, characterized in that: A transition structure (4) is provided between the connection structure (3) and the stress concentration simulation structure (1).

6. An engine disc test method, characterized in that: The characteristic simulation component design method according to any one of claims 1 to 5 is applied, and the test method comprises: A1. The simulation part is installed on the fatigue testing machine through the connection structure (3), and a cyclic tensile force equivalent to that of the actual wheel is applied; A2. Monitoring crack initiation and propagation behavior based on DIC technology; A3. Evaluate the crack growth life of the actual wheel disc based on the test results of the simulated component.

7. The engine disk test method according to claim 6, characterized in that: Step A2 includes: using the relative deformation amplitude of the simulated component under the high- and low-cycle random combination load spectrum to determine the time when the crack may initiate.

8. The engine disk test method according to claim 6, characterized in that: Step A2 includes: testing that the number of DIC measurement points is greater than or equal to 10.

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