A method and system for determining three types of cyclic stresses for wheel disc life assessment

Abstract

The application relates to the technical field of aero-engines and discloses a three-class cyclic stress determination method and system for wheel disc life evaluation, stress finite element simulation analysis of a wheel disc under transient load is carried out to obtain stress histories of key positions of the wheel disc at each time point under the same stress direction and the same temperature; stress inflection points in the stress histories are used to construct stress inflection point histories of the key positions of the wheel disc to realize three-class cyclic peak-valley stress determination and extraction. The application not only considers the influence of the transient load but also ensures that stress analysis is carried out under a unified direction benchmark through conversion of a direction cosine matrix, so that stress data and life data at different time points can be compared under the same temperature and stress direction conditions, thereby providing support for effective determination of wheel disc fatigue damage, and avoiding the situation that, in the prior art, there is a risk of analyzing wheel disc fatigue damage according to three-class cyclic stress without considering stress direction differences.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engines and discloses a method and system for determining three types of cyclic stresses for evaluating the life of a wheel disc. Background Art

[0002] The fatigue life damage of an aircraft engine impeller can be determined based on the stresses of three types of cycles: I, III, and IV. The stress results of these three types of cycles directly affect the life of the impeller. If the determined stress is unreasonable, there is a risk of the given impeller fatigue life being too high, and fatigue failure may occur prematurely during the life cycle. Therefore, it is particularly important to reasonably determine the three types of cyclic stresses of the impeller.

[0003] Key engine disc locations (such as the hole edge, fillet, and disc center) typically exhibit varying stress orientations at different moments in the transient history. Directly deriving three types of cyclic stresses from stress results obtained through simulation analysis to analyze disc fatigue damage can be risky. Furthermore, the actual operating load spectrum of aircraft engine discs is complex, while simplified load spectra are typically used in engineering transient analysis. Therefore, it is necessary to investigate how to reliably derive three types of cyclic stresses for disc damage analysis based on simplified load spectra to ensure disc safety and reliability. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for determining three types of cyclic stresses for wheel disc life assessment, which can provide support for the reasonable determination of wheel disc fatigue damage and ensure the safety and reliability of the wheel disc.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0006] A method for determining three types of cyclic stresses for disc life assessment includes:

[0007] Conduct finite element stress simulation analysis of the wheel under transient loads to obtain the first principal stress and the direction cosines corresponding to the first principal stress at key parts of the wheel at each time point; the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force, and transient wheel cavity pressure;

[0008] According to the direction cosines corresponding to the maximum value of the first principal stress, a direction cosine matrix and a transposed matrix of the direction cosines are constructed, and the key parts of the wheel at each time point are mapped using the direction cosine matrix and the transposed matrix of the direction cosines. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ;

[0009] According to the stress of the key parts of the roulette wheel at each moment and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ;

[0010] According to each time point Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ;

[0011] Determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ;

[0012] Determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle;

[0013] If the maximum inflection point stress occurs during the start-up phase of the aircraft engine, then After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in the process is determined as the peak stress of Class III cycle and Class IV cycle; if the maximum inflection point stress occurs in the non-starting stage, the maximum inflection point stress in the stress inflection point history is determined as the peak stress of Class III cycle and Class IV cycle.

[0014] Furthermore, a finite element stress simulation analysis of the wheel under transient load is carried out to obtain the first principal stress of the key parts of the wheel at each time point and the direction cosine corresponding to the first principal stress. The method includes:

[0015] A three-dimensional rectangular coordinate system O-xyz is constructed according to the right-hand rule, with a point on the central axis of the aircraft engine rotor as the coordinate origin O, the central axis as the y-axis, and a radial direction passing through the origin and located in the aircraft engine as the x-axis;

[0016] Conduct finite element simulation analysis of the wheel's stress under transient loads to obtain the wheel's stress history under transient loads;

[0017] According to the stress history, the temperature and stress components of the key parts of the wheel at each time point in the three-dimensional rectangular coordinate system are extracted, and the stress matrix of the key parts of the wheel at each time point is constructed. ,in, is the stress component of the wheel along the x direction, is the stress component of the wheel along the y direction, is the stress component of the wheel along the z direction, is the shear stress component of the wheel in the xoy plane, is the shear stress component of the wheel in the xoz plane, is the shear stress component of the wheel in the yoz plane;

[0018] according to The matrix eigenvalues ​​and eigenvectors at each time point are obtained, and the maximum value of the matrix eigenvalue at each time point is determined as the first principal stress at the corresponding time point. , the first principal stress The corresponding eigenvector is the first principal stress The direction cosines of .

[0019] Furthermore, the direction cosine matrix and the transposed matrix of the direction cosine are used to map the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ,in To construct a direction cosine matrix based on the direction cosines corresponding to the maximum value of the first principal stress, , for The transposed matrix of ,in is the cosine of the angle between the stress direction of the first principal stress maximum value and the x-axis, is the cosine of the angle between the stress direction of the first principal stress maximum value and the y-axis, is the cosine value of the angle between the stress direction of the first principal stress maximum value and the z-axis.

[0020] Furthermore, according to each time point Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The methods include:

[0021] Determine the stress history satisfy No. The moment is the stress inflection point, and then the starting moment Stress and end time Stress Together they form the stress inflection point process of the key parts of the wheel .

[0022] To achieve the above technical effects, the present invention further provides a system for determining three types of cyclic stresses for disc life assessment, which is used to implement the above method for determining three types of cyclic stresses for disc life assessment, comprising:

[0023] A simulation analysis module is used to perform finite element simulation analysis of the wheel's stress under transient loads, obtaining the first principal stress and the direction cosines corresponding to the first principal stress at key parts of the wheel at each time point; the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force, and transient wheel cavity pressure;

[0024] The stress analysis module is used to construct a direction cosine matrix and a transposed matrix of the direction cosines according to the direction cosines corresponding to the maximum value of the first principal stress, and use the direction cosine matrix and the transposed matrix of the direction cosines to calculate the stress of the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ;

[0025] The stress conversion module is used to convert the stress of the key parts of the wheel at each time point into and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ;

[0026] Stress inflection point analysis module is used to analyze the stress at each time point. Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ;

[0027] The first stress determination module is used to determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ;

[0028] The second stress determination module is used to determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle;

[0029] The third stress determination module is used to determine the stress inflection point when the maximum value of the inflection point stress appears in the starting phase of the aircraft engine. After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in the process is determined as the peak stress of Class III cycle and Class IV cycle; when the maximum inflection point stress occurs in the non-starting stage, the maximum inflection point stress in the stress inflection point history is determined as the peak stress of Class III cycle and Class IV cycle.

[0030] Furthermore, in the simulation analysis module, a method for performing a stress finite element simulation analysis of the wheel under transient loads and obtaining the first principal stress of key parts of the wheel at each time point and the direction cosines corresponding to the first principal stress includes:

[0031] A three-dimensional rectangular coordinate system O-xyz is constructed according to the right-hand rule, with a point on the central axis of the aircraft engine rotor as the coordinate origin O, the central axis as the y-axis, and a radial direction passing through the origin and located in the aircraft engine as the x-axis;

[0032] Conduct finite element simulation analysis of the wheel's stress under transient loads to obtain the wheel's stress history under transient loads;

[0033] According to the stress history, the temperature and stress components of the key parts of the wheel at each time point in the three-dimensional rectangular coordinate system are extracted, and the stress matrix of the key parts of the wheel at each time point is constructed. ,in, is the stress component of the wheel along the x direction, is the stress component of the wheel along the y direction, is the stress component of the wheel along the z direction, is the shear stress component of the wheel in the xoy plane, is the shear stress component of the wheel in the xoz plane, is the shear stress component of the wheel in the yoz plane;

[0034] according to The matrix eigenvalues ​​and eigenvectors at each time point are obtained, and the maximum value of the matrix eigenvalue at each time point is determined as the first principal stress at the corresponding time point. , the first principal stress The corresponding eigenvector is the first principal stress The direction cosines of .

[0035] Furthermore, in the stress conversion module, the direction cosine matrix and the transposed matrix of the direction cosine are used to transform the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ,in To construct a direction cosine matrix based on the direction cosines corresponding to the maximum value of the first principal stress, , for The transposed matrix of ,in is the cosine of the angle between the stress direction of the first principal stress maximum value and the x-axis, is the cosine of the angle between the stress direction of the first principal stress maximum value and the y-axis, is the cosine value of the angle between the stress direction of the first principal stress maximum value and the z-axis.

[0036] Furthermore, in the stress inflection point analysis module, the stress history is determined satisfy No. The moment is the stress inflection point, and then the starting moment Stress and end time Stress Together they form the stress inflection point process of the key parts of the wheel .

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention can reasonably determine the three types of cyclic stresses under the transient history of the wheel, provide support for the effective determination of the fatigue damage of the wheel, avoid the situation in the existing technology where the stress direction difference is not taken into account, resulting in a dangerous situation when analyzing the fatigue damage of the wheel based on the three types of cyclic stresses; and can more reasonably reflect the actual fatigue damage of the wheel, thereby improving the safety and reliability of the wheel during its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Flow chart of the method for determining three types of cyclic stresses for evaluating the life of a disc in Example 1 or 2;

[0040] Figure 2 This is a block diagram of the system structure for determining three types of cyclic stresses used in disc life assessment in Example 1;

[0041] Figure 3 This is a stress history curve diagram of the key parts of the wheel disc in Example 2;

[0042] Figure 4 The stress inflection point history curve diagram when the maximum inflection point stress occurs in the startup stage in Example 2;

[0043] Figure 5 The stress inflection point history curve diagram when the maximum inflection point stress occurs in the non-startup stage in Example 2;

[0044] Among them, 1. Simulation analysis module; 2. Stress analysis module; 3. Stress conversion module; 4. Stress inflection point analysis module; 5. First stress determination module; 6. Second stress determination module; 7. Third stress determination module. DETAILED DESCRIPTION

[0045] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0046] Example 1

[0047] See also Figures 1 to 2 , a method for determining three types of cyclic stresses for disc life assessment, including:

[0048] Conduct finite element stress simulation analysis of the wheel under transient loads to obtain the first principal stress and the direction cosines corresponding to the first principal stress at key parts of the wheel at each time point; the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force, and transient wheel cavity pressure;

[0049] According to the direction cosines corresponding to the maximum value of the first principal stress, a direction cosine matrix and a transposed matrix of the direction cosines are constructed, and the key parts of the wheel at each time point are mapped using the direction cosine matrix and the transposed matrix of the direction cosines. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ;

[0050] According to the stress of the key parts of the roulette wheel at each moment and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ;

[0051] According to each time point Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ;

[0052] Determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ;

[0053] Determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle;

[0054] If the maximum inflection point stress occurs during the start-up phase of the aircraft engine, then After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in the process is determined as the peak stress of Class III cycle and Class IV cycle; if the maximum inflection point stress occurs in the non-starting stage, the maximum inflection point stress in the stress inflection point history is determined as the peak stress of Class III cycle and Class IV cycle.

[0055] In this embodiment, by carrying out stress finite element simulation analysis of the wheel under transient load, the first principal stress of the key parts of the wheel at each time point and the direction cosine corresponding to the first principal stress are obtained, so as to analyze the stress of the key parts of the wheel at each time point in the direction corresponding to the maximum value of the first principal stress. and temperature The life value under the combined conditions, and then according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , to obtain the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature According to the stress history Stress inflection point Constructing the stress inflection point history of key parts of the wheel , in order to achieve the determination and extraction of three types of cyclic peak and valley stresses. The three-type cyclic stress determination method of the present invention not only takes into account the influence of transient loads, but also ensures that stress analysis is performed under a unified direction reference through the conversion of the direction cosine matrix. This allows stress data and life data at different time points to be compared under the same temperature and stress direction conditions, thereby providing support for the effective determination of fatigue damage of the wheel. It avoids the situation in the existing technology that does not consider the difference in stress direction, resulting in a dangerous situation when analyzing wheel fatigue damage based on three types of cyclic stress, thereby providing strong support for the safety and reliability assessment of the wheel during its service life.

[0056] The key parts in this embodiment include the hole edge, chamfer, disc center and other positions of the wheel disc.

[0057] Based on the same inventive concept, this embodiment further provides a system for determining three types of cyclic stresses for disc life assessment, which is used to implement the method for determining three types of cyclic stresses for disc life assessment, including:

[0058] Simulation analysis module 1 is used to perform finite element simulation analysis of the wheel under transient loads to obtain the first principal stress and the direction cosines corresponding to the first principal stress at key parts of the wheel at each time point; the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force and transient wheel cavity pressure;

[0059] Stress analysis module 2 is used to construct a direction cosine matrix and a transposed matrix of direction cosines according to the direction cosines corresponding to the maximum value of the first principal stress, and use the direction cosine matrix and the transposed matrix of direction cosines to calculate the stress of the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ;

[0060] Stress conversion module 3 is used to convert the stress of the key parts of the wheel at each time point into and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ;

[0061] Stress inflection point analysis module 4 is used to analyze the stress inflection point at each time point. Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ;

[0062] The first stress determination module 5 is used to determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ;

[0063] The second stress determination module 6 is used to determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle;

[0064] The third stress determination module 7 is used to determine the stress inflection point when the maximum value of the inflection point stress appears in the starting phase of the aircraft engine. After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in the process is determined as the peak stress of Class III cycle and Class IV cycle; when the maximum inflection point stress occurs in the non-starting stage, the maximum inflection point stress in the stress inflection point history is determined as the peak stress of Class III cycle and Class IV cycle.

[0065] Example 2

[0066] See also Figure 1 、 Figure 3 、 Figure 4 and Figure 5 This embodiment takes the determination of the peak-to-valley stresses of three types of cycles, I, III, and IV, at the key parts of a certain type of aircraft engine disc as an example to describe in detail the process of the method for determining the three types of cyclic stresses for disc life assessment of the present invention. The specific determination steps are as follows:

[0067] Step 1: Using a point on the central axis of the aircraft engine rotor as the coordinate origin O, the central axis as the y-axis, and a radial direction passing through the origin and located in the aircraft engine as the x-axis, construct a three-dimensional rectangular coordinate system O-xyz according to the right-hand rule;

[0068] Step 2: Conduct finite element simulation analysis of the stress of the wheel under transient load to obtain the stress history of the wheel under transient load;

[0069] In this embodiment, the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force and transient disc cavity pressure; among them, the transient temperature is determined by transient thermal analysis, and the remaining transient loads are determined by linear interpolation from typical state points.

[0070] Step 3: Based on the stress history, extract the temperature and stress components of the key parts of the wheel at each time point in the three-dimensional rectangular coordinate system, and construct the stress matrix of the key parts of the wheel at each time point. ,in, is the stress component of the wheel along the x direction, is the stress component of the wheel along the y direction, is the stress component of the wheel along the z direction, is the shear stress component of the wheel in the xoy plane, is the shear stress component of the wheel in the xoz plane, is the shear stress component of the wheel in the yoz plane;

[0071] Step 4: According to The matrix eigenvalues ​​and eigenvectors at each time point are obtained, and the maximum value of the matrix eigenvalue at each time point is determined as the first principal stress at the corresponding time point. , the first principal stress The corresponding eigenvector is the first principal stress The direction cosines of .

[0072] For example, in this embodiment, the key part of the roulette wheel is at the time point The six stresses below are =1085, =305, =478, =566、 =0, =0, according to Calculate the time point The matrix eigenvalues ​​are 8, 478, and 1382, and the corresponding eigenvectors are (0.4651, -0.8853, 0), (0, 0, 1), and (-0.8853, -0.4651, 0).

[0073] Step 5: Construct a direction cosine matrix and a transposed matrix of direction cosines according to the direction cosines corresponding to the maximum value of the first principal stress, and use the direction cosine matrix and the transposed matrix of direction cosines to map the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ;

[0074] In this embodiment, the key parts of the roulette wheel are at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ,in To construct a direction cosine matrix based on the direction cosines corresponding to the maximum value of the first principal stress, , for The transposed matrix of ,in is the cosine of the angle between the stress direction of the first principal stress maximum value and the x-axis, is the cosine of the angle between the stress direction of the first principal stress maximum value and the y-axis, is the cosine value of the angle between the stress direction of the first principal stress maximum value and the z-axis.

[0075] As time point The first principal stress The value is 1382, corresponding to the direction cosine 、 、 is -0.8853, -0.4651, 0; the six stresses at a certain time point are 432, 170, 224, 52, 0, 0; then the first principal stress at that time point is 442, according to , which is transformed into the maximum first principal stress at this moment The stress in the corresponding direction is 418.

[0076] Step 6: Based on the stress of the key parts of the wheel at each moment and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ;

[0077] Step 7: According to each time point Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ;

[0078] In this embodiment, the stress history curve of the key parts of the wheel disc is shown in FIG. Figure 3 , determine the stress history satisfy No. The moment is the stress inflection point, and then the starting moment Stress and end time Stress Together they form the stress inflection point process of the key parts of the wheel , the stress inflection point history constructed Curve Figure 4 .

[0079] Step 8. Determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ;

[0080] Step 9: Determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle;

[0081] Step 10: If the maximum inflection stress occurs during the start-up phase of the aircraft engine (e.g. Figure 4 ), then in the stress inflection point process After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in is determined as the peak stress of type III cycle and type IV cycle;

[0082] If the maximum inflection stress occurs in the non-startup phase (e.g. Figure 5 ), the maximum value of the inflection point stress in the stress inflection point history is determined as the peak stress of type III cycle and type IV cycle.

[0083] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining three types of cyclic stresses for disc life assessment, characterized in that: include: Conduct finite element stress simulation analysis of the wheel under transient loads to obtain the first principal stress and the direction cosines corresponding to the first principal stress at key parts of the wheel at each time point; the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force, and transient wheel cavity pressure; According to the direction cosines corresponding to the maximum value of the first principal stress, a direction cosine matrix and a transposed matrix of the direction cosines are constructed, and the key parts of the wheel at each time point are mapped using the direction cosine matrix and the transposed matrix of the direction cosines. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ; According to the stress of the key parts of the roulette wheel at each moment and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ; According to each time point Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ; Determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ; Determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle; If the maximum inflection point stress occurs during the start-up phase of the aircraft engine, then After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in is determined as the peak stress of type III cycle and type IV cycle; If the maximum value of the inflection point stress occurs in the non-startup stage, the maximum value of the inflection point stress in the stress inflection point history is determined as the peak stress of type III cycle and type IV cycle.

2. The method for determining three types of cyclic stresses for disc life assessment according to claim 1, characterized in that: The method for conducting stress finite element simulation analysis of the wheel under transient load and obtaining the first principal stress and the direction cosine corresponding to the first principal stress at each time point in the key parts of the wheel includes: A three-dimensional rectangular coordinate system O-xyz is constructed according to the right-hand rule, with a point on the central axis of the aircraft engine rotor as the coordinate origin O, the central axis as the y-axis, and a radial direction passing through the origin and located in the aircraft engine as the x-axis; Conduct finite element simulation analysis of the wheel's stress under transient loads to obtain the wheel's stress history under transient loads; According to the stress history, the temperature and stress components of the key parts of the wheel at each time point in the three-dimensional rectangular coordinate system are extracted, and the stress matrix of the key parts of the wheel at each time point is constructed. ,in, is the stress component of the wheel along the x direction, is the stress component of the wheel along the y direction, is the stress component of the wheel along the z direction, is the shear stress component of the wheel in the xoy plane, is the shear stress component of the wheel in the xoz plane, is the shear stress component of the wheel in the yoz plane; according to The matrix eigenvalues ​​and eigenvectors at each time point are obtained, and the maximum value of the matrix eigenvalue at each time point is determined as the first principal stress at the corresponding time point. , the first principal stress The corresponding eigenvector is the first principal stress The direction cosines of .

3. The method for determining three types of cyclic stresses for disc life assessment according to claim 2, characterized in that: The direction cosine matrix and the transposed matrix of the direction cosine are used to transform the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ,in To construct a direction cosine matrix based on the direction cosines corresponding to the maximum value of the first principal stress, , for The transposed matrix of ,in is the cosine of the angle between the stress direction of the first principal stress maximum value and the x-axis, is the cosine of the angle between the stress direction of the first principal stress maximum value and the y-axis, is the cosine value of the angle between the stress direction of the first principal stress maximum value and the z-axis.

4. The method for determining three types of cyclic stresses for disc life assessment according to claim 1, characterized in that: According to each time point Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The methods include: Determine the stress history satisfy No. The moment is the stress inflection point, and then the starting moment Stress and end time Stress Together they form the stress inflection point process of the key parts of the wheel .

5. A system for determining three types of cyclic stresses for disc life assessment, for implementing the method for determining three types of cyclic stresses for disc life assessment according to claim 1, characterized in that: include: A simulation analysis module is used to perform finite element simulation analysis of the wheel's stress under transient loads, obtaining the first principal stress and the direction cosines corresponding to the first principal stress at key parts of the wheel at each time point; the transient loads include transient temperature, transient speed, transient aerodynamic force, transient axial force, and transient wheel cavity pressure; The stress analysis module is used to construct a direction cosine matrix and a transposed matrix of the direction cosines according to the direction cosines corresponding to the maximum value of the first principal stress, and use the direction cosine matrix and the transposed matrix of the direction cosines to calculate the stress of the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ; The stress conversion module is used to convert the stress of the key parts of the wheel at each time point into and temperature , analyze and obtain the stress of the key parts of the wheel at each moment and temperature Life value under combined conditions; and according to the principle of equal life, the time points Stress under Uniformly converted to the temperature corresponding to the lowest point in life Stress under , get the key points of the roulette wheel at each moment Stress history under the same stress direction and temperature ; Stress inflection point analysis module is used to analyze the stress at each time point. Stress history under Stress inflection point And the time point corresponding to the stress inflection point , construct the stress inflection point history of the key parts of the wheel The stress inflection point history includes the stress history starting time Stress and end time Stress ; The first stress determination module is used to determine the stress inflection point history The minimum inflection stress in the stress cycle is the valley stress of type I stress cycle. The maximum value of the inflection point stress is the peak stress of type I stress cycle ; The second stress determination module is used to determine the stress inflection point history The minimum inflection point stress corresponding to the slow and medium state is the valley stress of the Class III cycle. , stress inflection point history The minimum inflection point stress corresponding to the mid-cruise state is the valley stress of the type IV cycle; The third stress determination module is used to determine the stress inflection point when the maximum value of the inflection point stress appears in the starting phase of the aircraft engine. After deleting the maximum stress value at the inflection point, the corrected stress inflection point history is obtained. , the corrected stress inflection point history The maximum inflection point stress in is determined as the peak stress of type III cycle and type IV cycle; When the maximum inflection point stress occurs in the non-startup stage, the maximum inflection point stress in the stress inflection point history is determined as the peak stress of type III cycle and type IV cycle.

6. The three-type cyclic stress determination system for disc life assessment according to claim 5, characterized in that: In the simulation analysis module, a method for performing a finite element simulation analysis of stress of the wheel under transient loads and obtaining the first principal stress of key parts of the wheel at each time point and the direction cosines corresponding to the first principal stress includes: A three-dimensional rectangular coordinate system O-xyz is constructed according to the right-hand rule, with a point on the central axis of the aircraft engine rotor as the coordinate origin O, the central axis as the y-axis, and a radial direction passing through the origin and located in the aircraft engine as the x-axis; Conduct finite element simulation analysis of the wheel's stress under transient loads to obtain the wheel's stress history under transient loads; According to the stress history, the temperature and stress components of the key parts of the wheel at each time point in the three-dimensional rectangular coordinate system are extracted, and the stress matrix of the key parts of the wheel at each time point is constructed. ,in, is the stress component of the wheel along the x direction, is the stress component of the wheel along the y direction, is the stress component of the wheel along the z direction, is the shear stress component of the wheel in the xoy plane, is the shear stress component of the wheel in the xoz plane, is the shear stress component of the wheel in the yoz plane; according to The matrix eigenvalues ​​and eigenvectors at each time point are obtained, and the maximum value of the matrix eigenvalue at each time point is determined as the first principal stress at the corresponding time point. , the first principal stress The corresponding eigenvector is the first principal stress The direction cosines of .

7. The three-type cyclic stress determination system for disc life assessment according to claim 6, characterized in that: In the stress conversion module, the direction cosine matrix and the transposed matrix of the direction cosine are used to transform the key parts of the wheel at each time point. The stress matrix under the first principal stress is converted to the stress under the direction corresponding to the maximum value of the first principal stress. ,in To construct a direction cosine matrix based on the direction cosines corresponding to the maximum value of the first principal stress, , for The transposed matrix of ,in is the cosine of the angle between the stress direction of the first principal stress maximum value and the x-axis, is the cosine of the angle between the stress direction of the first principal stress maximum value and the y-axis, is the cosine value of the angle between the stress direction of the first principal stress maximum value and the z-axis.

8. The three-type cyclic stress determination system for disc life assessment according to claim 5, characterized in that: In the stress inflection point analysis module, determine the stress history satisfy No. The moment is the stress inflection point, and then the starting moment Stress and end time Stress Together they form the stress inflection point process of the key parts of the wheel .

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