Characteristic simulation part design method and engine wheel disc test method

Abstract

The invention discloses a feature simulation piece design method and an engine wheel disc test method.The feature simulation piece design method is used for a crack propagation test of an engine wheel disc, and the feature simulation piece design method comprises the steps that S1, a three-dimensional geometric model is constructed based on actual components of the engine wheel disc; s2, establishing a finite element analysis model based on the three-dimensional geometric model of the actual component of the engine wheel disc and the material parameters; s3, designing a simulation piece, enabling the simulation piece to have a stress concentration simulation structure and a stress gradient distribution simulation structure, and determining an initial basic size of the simulation piece; s4, performing finite element simulation analysis; and S5, judging whether the stress test data of the simulation piece is consistent with the stress test data of the actual component or not, if so, completing the design of the simulation piece, and if not, adjusting the size of the stress concentration simulation structure of the simulation piece and / or adjusting the size of the stress gradient distribution simulation structure of the simulation piece, and repeating the steps S4-S5 until the stress test data of the simulation piece is consistent with or tends to be consistent with the stress test data 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 characteristic simulation component design method. In addition, the present invention also relates to an engine wheel disc test method including the characteristic simulation component design method. Background Art

[0002] The engine impeller needs to be designed for damage tolerance, that is, to calculate the crack propagation life of the impeller. In order to verify the analysis results, verification tests need to be carried out, but the cost of aircraft engine impellers is high, and the cost of crack propagation tests using actual impellers or simulated impellers with structures close to the impeller plate is very high. In the early stages of design, it is necessary to design more economical simulation parts based on the characteristics of key parts of the impeller to conduct fatigue life tests to meet the needs of analysis method verification and design iteration.

[0003] However, in actual research, it was found that it is necessary to find suitable simulation parts structure and parameters so that it can accurately simulate the stress gradient characteristics of the actual wheel disc, but the traditional simulation parts with circular hole characteristics have many problems and cannot meet the actual needs well. For example, the technical scheme with patent number: CN202311219448.8 discloses a design method for simulation parts for predicting the low-cycle fatigue performance of engine wheel discs, which performs equivalent simplification processing on the structural features, uses the equivalent simplified structural features as the gauge length segment, and adjusts the relative position relationship (parallel offset position and distance) between the clamping section and the gauge length segment to make the stress gradient and fatigue failure characteristics of the simulation part 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 results and the actual component stress test data is weak. For example, the technical solution of patent number: CN201810797101.4 discloses a method for designing a simulation part of the crack extension characteristics of the center hole of a centrifugal impeller. The geometric characteristics and operating conditions of the centrifugal impeller are taken into consideration, 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 possible to fully capture the stress gradient characteristics of all local stress concentration areas in the actual wheel, especially when simulating actual load conditions with high complexity. This simplification may cause the simulation results to deviate from the actual situation in some cases. On the other hand, this design method considers the equivalence of circumferential stress, while the driving force for crack extension is the first principal stress. When applied to crack extension tests, the test results of the simulation parts will be inconsistent with the test results of the actual disk. Summary of the invention

[0004] The present invention provides a characteristic simulation part design method and an engine wheel disc test method to solve the technical problems in the prior art of engine wheel disc crack extension simulation test that the simulation part design has poor flexibility, limited adjustment range, and the actual simulation results are difficult to accurately reflect the real test results.

[0005] According to one aspect of the present invention, a method for designing a characteristic simulation part is provided, wherein the characteristic simulation part is used for a crack growth test of an engine wheel disc, and the method for designing a characteristic simulation part 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 part, 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 part has a stress concentration simulation structure, a stress gradient distribution simulation structure and connection structures arranged at both ends of the simulation part, wherein the stress concentration simulation structure includes an elliptical hole structure formed in the middle of the simulation part, and the stress gradient distribution simulation structure includes arc structures formed on both sides of the middle of the simulation part, and determine the initial basic size of the simulation part; 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, respectively; 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.

[0006] 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 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.

[0007] As a further improvement of the above technical solution, 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.

[0008] As a further improvement of the above technical solution, the connection structure includes connection holes opened at both ends of the simulation part, and the connection holes are used to connect with the fixture of the test equipment through a pin shaft.

[0009] As a further improvement of the above technical solution, a transition structure is provided between the connection structure and the stress concentration simulation structure.

[0010] According to another aspect of the present invention, there is also provided an engine wheel disc test method, which includes the above-mentioned characteristic simulation part design method, and the test method includes: A1. Install the simulation part on the fatigue testing machine through the connection structure and apply a cyclic tension equivalent to the actual wheel disc; 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.

[0011] As a further improvement of the above technical solution, 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 moment when the crack may initiate.

[0012] As a further improvement of the above technical solution, step A2 includes: the number of test DIC measurement points is greater than or equal to 10.

[0013] The present invention has the following beneficial effects: 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.At the same time, this design method is more flexible. It can adjust the stress concentration simulation structure and the stress gradient distribution simulation structure according to different simulation requirements to make multiple combinations, realize the accurate simulation of the characteristics of the actual components, and compare and verify the simulation results with the stress test data of the actual components through finite element analysis to further ensure the accuracy of the simulation. The actual model stress is calculated as the simulation basis through actual model construction, and the simulation component parameters are adjusted and optimized through multiple simulations. Finally, its effectiveness is verified. The overall process is streamlined and closely related to form a complete closed loop to ensure the scientificity and accuracy of the simulation component design. The interference between the stress concentration simulation structure and the stress gradient distribution simulation structure of this design method is low, and can be adjusted separately based on the parameter decoupling method. Based on this, the number of design iterations can be compressed to no more than 4 rounds, which improves the simulation accuracy and greatly improves the design optimization efficiency. ;

[0014] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a flow chart of a method for designing a characteristic simulation component according to a preferred embodiment of the present invention; Figure 2 is a schematic structural diagram of a characteristic simulation component of a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the first principal stress gradient data of an actual component of the first embodiment of the present invention; Figure 4 It is a schematic diagram of the structure and stress distribution of the characteristic simulation part of the first embodiment of the present invention; Figure 5 is a schematic diagram of stress distribution of an elliptical hole structure of a characteristic simulation component of the first embodiment of the present invention; Figure 6 is the first principal stress gradient 5 mm away from the hole edge under the first preset condition in the first embodiment of the present invention; Figure 7 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the first preset condition in the first embodiment of the present invention; Figure 8 is the first principal stress gradient 5 mm away from the hole edge under the second preset condition in Example 1 of the present invention; Fig. 9 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the second preset condition in the first embodiment of the present invention; Fig.10is the first principal stress gradient 5 mm away from the hole edge under the third preset condition in Example 1 of the present invention; Fig.11 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the third preset condition in the first embodiment of the present invention; Fig.12 is the first principal stress gradient 5 mm away from the hole edge under the fourth preset condition in Example 1 of the present invention; Fig.13 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the fourth preset condition in the first embodiment of the present invention; Fig.14 It is a cloud diagram of the first principal stress distribution of the characteristic simulation component structure in comparative example 1 of the present invention; Fig.15 is a stress distribution cloud diagram of the area near the circular hole in Comparative Example 1 of the present invention; Fig.16 It is the first principal stress gradient at 5 mm from the hole edge when analyzing the influence of the circular hole diameter in Comparative Example 1 of the present invention; Fig.17 It is the first principal stress gradient at 0.5 mm from the hole edge when analyzing the influence of the circular hole diameter in Comparative Example 1 of the present invention; Fig.18 It is the first principal stress gradient 5 mm away from the hole edge when analyzing the influence of the outer curvature in the comparative example 1 of the present invention; Fig.19 It is the first principal stress gradient at 0.5 mm from the hole edge when analyzing the influence of the outer curvature in Comparative Example 1 of the present invention; Fig. 20 It is a schematic diagram of analyzing the effect of notch radius on stress gradient in comparative example 1 of the present invention; Fig.21 It is a schematic diagram of analyzing the effect of the notch net cross-sectional width on the stress gradient in Comparative Example 1 of the present invention; Fig. 22 It is a schematic diagram of the structure of the simulation component in comparative example 1 of the present invention.

[0016] Legend: 1. Stress concentration simulation structure; 2. Stress gradient distribution simulation structure; 3. Connection structure; 4. Transition structure. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0018] Figure 1 is a flow chart of a method for designing a characteristic simulation component according to a preferred embodiment of the present invention; Figure 2 is a schematic structural diagram of a characteristic simulation component of a preferred embodiment of the present invention; Figure 3This is a schematic diagram of the first principal stress gradient data of an actual component of the first embodiment of the present invention; Figure 4 It is a schematic diagram of the structure and stress distribution of the characteristic simulation part of the first embodiment of the present invention; Figure 5 is a schematic diagram of stress distribution of an elliptical hole structure of a characteristic simulation component of the first embodiment of the present invention; Figure 6 is the first principal stress gradient 5 mm away from the hole edge under the first preset condition in the first embodiment of the present invention; Figure 7 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the first preset condition in the first embodiment of the present invention; Figure 8 is the first principal stress gradient 5 mm away from the hole edge under the second preset condition in Example 1 of the present invention; Fig. 9 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the second preset condition in the first embodiment of the present invention; Fig.10 is the first principal stress gradient 5 mm away from the hole edge under the third preset condition in Example 1 of the present invention; Fig.11 is the first principal stress gradient at a distance of 0.5 mm from the hole edge under the third preset condition in the first embodiment of the present invention; Fig.12 is the first principal stress gradient 5 mm away from the hole edge under the fourth preset condition in Example 1 of the present invention; Fig.13 It is the first principal stress gradient 0.5 mm away from the hole edge under the fourth preset condition in Example 1 of the present invention.

[0019] like Figure 1 and Figure 2 As shown, the characteristic simulation part design method of this embodiment, the characteristic simulation part is used for the crack extension test of the engine wheel, and the characteristic simulation part design method includes: 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 part, 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 part 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 part, wherein the stress concentration simulation structure 1 includes an elliptical hole structure formed in the middle of the simulation part, and the stress gradient distribution simulation structure 2 includes arc structures formed on both sides of the middle of the simulation part, and the initial basic size of the simulation part 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, respectively; 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.

[0020] The connection structure 3 is used to connect with the test equipment to transfer the load, and the specific structure can be designed according to the test requirements; the first preset position is selected as the front end position close to the main area affecting the crack growth life, and the second preset position is selected as the rear end position close to the main area affecting the crack growth life; In a specific embodiment, the first preset position is 0.5 mm away from the elliptical hole structure, and the second preset position is 5 mm away from the elliptical hole structure. The preset percentage is preferably 5%, and can also be adjusted according to actual needs; it should be noted that the adjustment gradient of the aspect ratio of the elliptical hole structure in step S5 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, wherein, for every increase of 0.01 in the aspect ratio of the elliptical hole structure, the gradient at 0.5 mm from the hole edge decreases by 5% to 8%, and for every decrease of 50 mm in the radius of the arc structure, the gradient attenuation rate at 5 mm increases by 10% to 15%; It should be noted that in the test process before the actual design, the influence of the elliptical hole structure characteristics on the stress gradient of the characteristic simulation part was analyzed. The structure and stress distribution of the characteristic simulation part with elliptical hole structure are shown in Figure 3 As shown. The results show that the characteristic simulation parts with aspect ratios of 0.125 and 0.1 both show a trend of slower stress amplitude reduction as the radius of the outer arc structure decreases. When the aspect ratio is fixed, increasing the height of the elliptical hole structure also shows a trend of slower stress amplitude reduction. For all test conditions, whether the aspect ratio is 0.125 or 0.1, the smaller the outer arc radius, the slower the stress amplitude reduction rate, that is, the radius change of the arc structure is positively correlated with the stress gradient change, which also confirms that the outer arc radius is the decisive factor in controlling the stress gradient change rate.

[0021] It can be understood that the present design method first constructs a three-dimensional geometric model of the actual component and collects and obtains various performance parameters of the actual component material, and then 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 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 part has an elliptical hole structure formed in the middle of the simulation part as a stress concentration simulation structure 1, and arc structures formed on both sides of the middle of the simulation part as stress gradient distribution simulation structure 2, and utilizes the stress concentration characteristic 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 on the periphery of the elliptical hole structure, and effectively disperses the 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 Finite element simulation analysis is used to analyze 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 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. This design method simulates the stress concentration area and stress gradient of the actual component more accurately. By optimizing the size of the stress concentration simulation structure 1 and the size of the stress gradient distribution simulation structure 2 of the simulation part, the stress gradient of the simulation part is matched with the actual wheel disc height, and has higher simulation accuracy, avoiding the problem of inconsistency between the simulation part test results and the real disc test results due to incomplete stress considerations.At the same time, this design method is more flexible. According to different simulation requirements, the stress concentration simulation structure 1 and the stress gradient distribution simulation structure 2 can be adjusted to perform multiple combinations to achieve accurate simulation of the characteristics of the actual component. The simulation results are compared and verified with the stress test data of the actual component through finite element analysis to further ensure the accuracy of the simulation. The actual model stress is calculated as the simulation basis through actual model construction, and the simulation component parameters are adjusted and optimized through multiple simulations. Finally, its effectiveness is verified. The overall process is streamlined and closely related to form a complete closed loop to ensure the scientificity and accuracy of the simulation component design. The interference between the stress concentration simulation structure 1 and the stress gradient distribution simulation structure of this design method is low, and can be adjusted separately based on the parameter decoupling method. Based on this, the number of design iterations can be compressed to no more than 4 rounds, which improves the simulation accuracy and greatly improves the design optimization efficiency. ;

[0022] Further, step S1 includes: using computer-aided design software, constructing 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; specifically, using professional computer-aided design software such as SolidWorks and CATIA, constructing its three-dimensional geometric model according to the precise size, shape and other parameters of the actual component, and this model will serve as the basic framework for subsequent analysis and simulation, accurately presenting the geometric form of the actual component, and providing a prerequisite for accurate simulation of stress distribution; it should be understood that for complex components such as aircraft engine wheels, the model needs to carefully depict its contours, hole positions, grooves and other features to ensure that they are highly consistent with the actual components; material parameters include density, elastic modulus, Poisson's ratio; specifically, collecting various performance parameters of the actual component materials, 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-strain response of components under stress. For example, TC4 (special) alloy, its unique material characteristic parameters will directly affect the stress distribution law of the wheel under different working conditions, and accurately obtaining these parameters is the basis for subsequent accurate simulation.

[0023] Furthermore, step S2 also includes: setting boundary conditions and load conditions based on the working state of the actual component, setting typical conditions to cover various stress states under the working state of the actual component, and specifically, in the process of model establishment, it is necessary to reasonably set parameters such as boundary conditions and load conditions 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 in actual work, such as the stress of the engine wheel under conditions such as high-speed rotation and temperature changes. Through precise calculation, the distribution law of stress at different positions of the component and the gradient information of stress changes with position are obtained, providing a key basis for the design of simulation parts.

[0024] It can be understood that this design method improves the central circular hole structure of the conventional simulation part into an elliptical hole structure to simulate the stress concentration area, and designs an arc structure to simulate the stress gradient distribution, fully considering and simulating the first principal stress gradient characteristics, providing a more reliable experimental model for the study of crack propagation in key parts of the wheel, and helping to improve the prediction accuracy of the crack propagation performance of components such as the wheel under actual working conditions; on the other hand, this simulation part has a better simulation effect on complex components, and the simulation of the stress concentration area of ​​the elliptical hole structure and the stress gradient distribution of the arc structure can better adapt to complex stress states, 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 promotion prospects and practical application value.

[0025] In some embodiments, the connection structure 3 includes connection holes opened at both ends of the simulation part, and the connection holes are used to connect with the fixture of the test equipment through a pin shaft.

[0026] In some embodiments, a transition structure 4 is provided between the connection structure 3 and the stress concentration simulation structure 1 to smoothly connect the two to ensure structural continuity, so that the load is smoothly transferred and simulation errors caused by stress concentration or poor transfer are avoided.

[0027] On the other hand, the preferred embodiment further provides an engine wheel disc test method, which includes the above-mentioned characteristic simulation component design method, and the test method includes: A1. The simulation part is installed on the fatigue testing machine through the connection structure 3, and a cyclic tension equivalent to that of the actual wheel is applied; it is realized based on the existing method and will not be elaborated on; it should be noted that the test piece can be pre-processed before the test, and the test piece can be painted to obtain a high-contrast random grayscale distribution image, that is, by adding speckles to arrange random patterns so that the image of the tested piece is clear and recognizable in the camera; A2. Monitoring crack initiation and propagation behavior based on DIC technology; Preferably, in the crack initiation stage, step A2 includes: using the relative deformation amplitude of the simulation part under the action of the high- and low-cycle random combination load spectrum to determine the moment when the crack may initiate; using a fatigue testing machine to monitor the relative displacement change trend of the characteristic simulation part during the crack extension test, and finding the position of the starting cycle number of the crack initiation stage. In the early stage, through a preliminary test, it was found that the relative displacement of the characteristic simulation part in the initiation and extension stage increased significantly at about 5400 load cycles, and the simulation part broke after the fatigue test was continued to about 5800 times; therefore, in order to save DIC sampling time and improve the efficiency of test and subsequent analysis, the relative deformation amplitude of the simulation part under the action of the high- and low-cycle random combination load spectrum is used to determine the moment when the crack may initiate, and then the DIC test and analysis system is started to test the transient load crack extension characteristics and development trends of the weak structural strength area of ​​the simulation part; Preferably, in the crack extension stage, step A2 includes: the number of test DIC measurement points is greater than or equal to 10; specifically, the displacement is measured by the digital image correlation (DIC) method, and its basic technology is: using the initial reference image, correlating the subsequent image of the deformed object with the reference image, and finding the maximum correlation position between the two images. The corresponding translation can be used as a measure of displacement. The principle of the DIC method for measuring crack opening force is that under the action of the load P in the form of a triangular wave, the crack tip opening displacement (COD) stabilizes near the minimum value within a certain range near the minimum load, corresponding to the crack closure 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 endpoint of the line segment corresponding to the minimum value is the load required for the crack to open, recorded as Pop. The test interval determines the degree of visualization of the crack extension of the test piece, so the DIC test interval is as short as possible to obtain enough data points, and the number of DIC measurement points in subsequent tests is arranged to be more than 10; A3. Evaluate the crack growth life of the actual wheel disc based on the test results of the simulated component.

[0028] Embodiment 1 This embodiment applies the characteristic simulation component design method of the above preferred embodiment, and extracts the first principal stress gradient data of the wheel disc test area (maximum distance 15.92mm) and performs normalization processing for the static analysis and stress gradient of the test part of TC4 (special) alloy wheel disc. The results are as follows: Figure 3 shown.

[0029] In this embodiment, the first preset position and the second preset position are set to 0.5mm and 5mm respectively, the length of the elliptical hole is kept unchanged at 8mm, the height of the hole is changed, and the influence of the elliptical height on the stress gradient is analyzed. The heights of the elliptical hole are 4mm, 2mm, 1mm and 0.5mm respectively. It can be seen that the smaller the height of the elliptical hole, the slower the decrease of the stress gradient at the edge of the hole; when the elliptical hole is 8mm long and 1mm high, the stress gradient at the edge of the hole of the characteristic simulation part is closest to the actual compressor disk stress level.

[0030] In this embodiment, the first preset position and the second preset position are taken as 0.5mm and 5mm respectively, the height of the elliptical hole is kept unchanged at 1mm, the length of the hole is changed, and the influence of the length of the ellipse on the stress gradient is analyzed. The lengths of the elliptical hole are 10mm, 8mm, 6mm and 4mm respectively. It can be seen that the larger the length of the elliptical hole, the slower the decrease of the stress gradient at the edge of the hole; when the height of the elliptical hole is 1mm and the length is 10mm, the stress gradient at the edge of the hole of the characteristic simulation part is closest to the actual stress level of the compressor disk; for further verification, the height of the elliptical hole is kept unchanged at 1mm, the length of the hole is continuously increased and the stress gradient analysis is performed. The lengths of the elliptical hole are 15mm, 12mm, 10mm and 8mm respectively. It can be seen that the larger the length of the elliptical hole, the slower the decrease of the stress gradient at the edge of the hole; when the height of the elliptical hole is 1mm and the length is 12mm, the stress gradient at the edge of the hole of the characteristic simulation part is closest to the actual stress level of the compressor disk.

[0031] In this embodiment, the first preset position and the second preset position are 0.5mm and 5mm respectively. The finite element analysis software is used for simulation to optimize the size of the elliptical hole structure and the radius of the outer arc structure to achieve a high degree of matching with the actual component stress distribution. The circular hole gap in the middle of the characteristic simulation part is innovatively adjusted to an elliptical hole structure, and the influence of the elliptical hole gap characteristics on the stress gradient of the characteristic simulation part is analyzed. The structure of the characteristic simulation part with an elliptical hole structure and its stress distribution are shown in FIG. Figure 4 and Figure 5 As shown. The results show that the characteristic simulation parts with aspect ratios of 0.125 and 0.1 both show a trend of slower stress amplitude reduction rate as the outer curvature radius decreases. When the aspect ratio is fixed, increasing the height of the elliptical hole structure (for example, from 1mm to 1.5mm) also shows a trend of slower stress amplitude reduction rate. 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 curvature radius is the decisive factor in controlling the rate of change of the stress gradient. When the aspect ratio of the elliptical hole structure is 0.125 and the length is 8mm, and the outer curvature radius of the elliptical hole structure is ∞ (straight line), 500mm, 250mm and 100mm respectively, the first principal stress gradient 5mm away from the edge of the elliptical hole structure is as follows Figure 6As shown, the first principal stress gradient at 0.5 mm from the hole edge is Figure 7 As shown, we can see: 1) The smaller the arc of the outer arc structure of the elliptical hole structure, the slower the decrease of the stress gradient at the hole edge; 2) When the outer curvature is 100 mm, the stress gradient at the hole edge of the characteristic simulation part partially exceeds the actual wheel stress level.

[0032] When the aspect ratio of the elliptical hole structure is 0.1 and the length is 10 mm, and the outer radius of the elliptical hole structure is ∞ (straight line), 500 mm, 250 mm and 100 mm, the first principal stress gradient 5 mm away from the hole edge is as follows: Figure 8 As shown, the first principal stress gradient at a distance of 0.5 mm from the edge of the elliptical hole is as follows: Fig. 9 As shown, we can see: 1) The smaller the arc of the outer arc structure of the elliptical hole structure, the slower the decrease of the stress gradient at the hole edge; 2) When the outer curvature is 250 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual wheel stress level.

[0033] When the aspect ratio of the elliptical hole structure is 0.1 and the length is 15 mm, and the outer radius of the elliptical hole structure is ∞ (straight line), 500 mm, 250 mm and 100 mm, the first principal stress gradient 5 mm away from the hole edge is as follows: Fig.10 As shown, the first principal stress gradient at 0.5 mm from the hole edge is Fig.11 As shown, we can see: 1) The smaller the arc of the outer arc structure of the elliptical hole structure, the slower the decrease of the stress gradient at the hole edge; 2) When the outer curvature is 250 mm, the stress gradient at the hole edge of the characteristic simulation part is closest to the actual wheel stress level.

[0034] The final simulation component structural dimensions and designed characteristic simulation component parameters are as follows: the length of the elliptical hole is 15 mm, the aspect ratio is 0.1, and the arc of the arc structure outside the elliptical hole structure is 225 mm. At this time, the first principal stress gradient of the characteristic simulation component 5 mm away from the hole edge is as follows: Fig.12 As shown, the first principal stress gradient at 0.5 mm from the hole edge is Fig.13 It can be seen that the stress gradient of the designed characteristic simulation part is close to the actual wheel disk stress level and can be used for crack growth test of wheel disk characteristic simulation part.

[0035] Table 1 Effect of elliptical hole size on stress gradient of characteristic simulation parts

[0036] Combined with the above analysis, the contents of Table 1 are obtained. Based on the above analysis results, the structural dimensions of the simulation part are finally determined. The notch parameters of the designed characteristic simulation part are an elliptical hole length of 15 mm, an aspect ratio of 0.1, and an outer curvature of the notch structure of 225 mm. At this time, the first principal stress gradient of the characteristic simulation part at different positions (such as 5 mm and 0.5 mm) from the hole edge is very close to the actual wheel stress level, indicating that the simulation part can accurately simulate the stress distribution characteristics of the actual wheel, and can be used for crack propagation tests of characteristic simulation parts of the wheel, providing a reliable test model for crack propagation research of components such as wheels, and based on the actual implementation effect of this embodiment, the adjustment step length of step S5 (i.e., the adjustment step length of the arc structure is 50 mm, and the adjustment step length of the aspect ratio 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.

[0037] Moreover, after experimental verification, the stress gradient of the simulated parts under variable amplitude loading conditions measured by the DIC strain and measurement system were basically consistent.

[0038] Comparative Example 1 In this comparative example, reference Fig.14 and Fig.15 The middle part of the simulation part is a circular hole structure. The structural dimensions of the characteristic simulation part are kept unchanged, and the diameter of the circular hole is changed to analyze the influence of the stress gradient. When the diameter of the circular hole is 0.5mm, 1mm, 2mm, and 4mm respectively, the reference Fig.16 and Fig.17 It can be seen that as the diameter of the circular hole increases, the stress gradient at the hole edge decreases more slowly, and the stress gradient decrease rate of the simulation part with circular hole characteristics is much higher than the stress level of the actual compressor disk. The structure of the simulation part with this characteristic cannot meet the requirements; reference Fig.18 and Fig.19 The stress gradient of the hole edge of the characteristic simulation part with a circular hole notch decreases too fast. A certain curvature is introduced on the outside of the notch structure to observe the influence of the outer curvature on the stress gradient of the hole edge. The diameter of the circular hole notch of the characteristic simulation part is kept unchanged at 2mm. The stress gradient of the hole edge under the working conditions of the outer curvature diameter being ∞, 500mm, 250mm, and 50mm is analyzed. It can be seen that as the radius of the outer curvature increases, the stress gradient of the hole edge decreases more slowly, but this effect is minimal, which is consistent with the conclusion drawn in the reference "Wei Dasheng et al., Design method and experimental verification of simulation test piece for center hole of aircraft engine disk, Journal of Aerodynamics", that is, the stress gradient of the circumferential stress of the center hole edge of the disk is too small along the radial direction. Fig. 20 and Fig.21, it is impossible to obtain a stress gradient equivalent to it by changing the notch geometry. In order to characterize the stress gradient characteristics caused by the center hole edge structure of the wheel, the notch geometry of the wheel center stress gradient characteristic simulation part directly adopts the curvature radius at the wheel center, only considering the consistency of the stress amplitude, while ignoring the consistency of the stress gradient. Fig. 22 No matter how the size of the circular hole feature simulation part is changed, the stress gradient level at the hole edge of the finally designed disk center stress gradient feature simulation part cannot meet the stress gradient characteristics of the actual compressor disk.

[0039] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "front", "rear", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, 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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