Wheel disc low-cycle fatigue test load coefficient determination method and device and application

Abstract

The invention relates to the technical field of aero-engines, and discloses a wheel disc low-cycle fatigue test load coefficient determination method, a wheel disc low-cycle fatigue test load coefficient determination device and application of the wheel disc low-cycle fatigue test load coefficient determination method. Based on stress characteristics and temperature characteristics of key parts of a wheel disc in an engine state, reasonable determination of a low-cycle fatigue test load coefficient of the wheel disc and conversion of the fatigue life of the wheel disc are realized by comprehensively considering the influence of a peak-valley value stress ratio of the wheel disc in a working state on the fatigue life of the wheel disc and a change rule of material performance along with temperature. The safety risk caused by the fact that the load coefficient deviates from the reality is reduced, and the design and use of the wheel disc are safer and more reliable; by correcting the load coefficient, the fatigue damage of the engine in the test state can be truly reflected, so that the safe life of the wheel disc is effectively determined, and support is provided for the life management of the wheel disc.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engines and discloses a method, a device and an application for determining a load coefficient of a wheel disc low-cycle fatigue test. Background Art

[0002] As a key component, the rotor disc of an aircraft engine can have catastrophic consequences if damaged, and its failure rate must be controlled to be extremely rare. Statistics show that low-cycle fatigue is the most important factor affecting and limiting the service life of the rotor disc. Currently, its safe life is mainly determined through low-cycle fatigue testing of the rotor disc. Since the low-cycle fatigue test of the rotor disc is usually carried out under uniform temperature conditions, the stress and temperature of the key parts of the rotor disc under the test state are different from those under the engine state. In order to characterize the effectiveness of the rotor disc fatigue test, the load factor method recommended by the Spey MK202 engine stress standard is currently widely used, that is, the load factor is determined according to (peak stress under test state × tensile strength of the disc material under engine state) / (peak stress under engine state × tensile strength of the disc material under test state).

[0003] Since valley stress generally exists in key parts of the wheel under test conditions, and the current method does not consider the influence of valley stress, there is a situation where the wheel load coefficient is 1, but the engine state life is inconsistent with the test state life; in addition, the existing method considers the temperature difference between the key parts of the test state and the engine state through tensile strength. When the change patterns of tensile strength and fatigue performance with temperature are very different, the determined load coefficient deviates from the actual one, which may cause the determined wheel life to be much longer than the actual one, which is dangerous.

[0004] Furthermore, when inferring engine life from disk fatigue test results using relative linear damage theory, the effect of load factors on damage is not considered. This can result in a potentially dangerously high calculated life for the engine disk, posing certain risks to engineering operations. Therefore, it is crucial to rationally determine the load factors for disk low-cycle fatigue testing and to employ a reasonable method for calculating disk life. Summary of the Invention

[0005] The purpose of the present invention is to provide a method, device and application for determining the load coefficient of a low-cycle fatigue test of a wheel disc, which can realize the reasonable determination of the load coefficient of the low-cycle fatigue test of the wheel disc, reduce the safety risks caused by the deviation of the load coefficient from the actual one, make the design and use of the wheel disc safer and more reliable, and ensure that the fatigue damage under the engine state can be truly reflected under the test state by correcting the load coefficient.

[0006] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0007] A method for determining a load factor of a wheel disc low cycle fatigue test, comprising:

[0008] Conduct finite element analysis of the wheel in the engine state and obtain the stress spectrum σ of each key part of the wheel i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves;

[0009] Based on the different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, a basic model of equivalent stress of the wheel disc material at each typical temperature based on stress ratio is constructed, and the equivalent stress analysis model at different temperatures is obtained by linear interpolation;

[0010] Based on the fatigue life values at each typical temperature on the fatigue life curve of the wheel material and the equivalent stresses of different stress ratios at each typical temperature obtained according to the equivalent stress basic model, a basic material life model between the equivalent stress at typical temperature and the fatigue life of the wheel material is fitted, and the wheel life analysis model at different temperatures is obtained through logarithmic linear interpolation;

[0011] According to the temperature of each key part of the wheel disc under the engine state and the peak stress and valley stress in the stress spectrum, the equivalent stress analysis model at the corresponding temperature is used to analyze and obtain the equivalent stress σ of each key part of the wheel disc under the engine state. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ;

[0012] Extract the N i The minimum value N in i,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ;

[0013] Take T i,min As the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ;

[0014] According to the engine status, the life of each key part of the wheel is N iCorresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i ,use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

[0015] Furthermore, the equivalent stress basic model is σ e =σ max (1-R) m , where σ e is the equivalent stress that comprehensively considers the influence of stress ratio R, where σ max is the peak stress, m is the wheel material constant determined by the test, the value range of m is 0.45-0.65, the stress ratio σ min is the valley stress.

[0016] Furthermore, the equivalent stress σ e The basic model of material life between fatigue life N is lgN=AB·lgσ e , where A and B are obtained by data fitting.

[0017] In order to achieve the above technical effects, the present invention also provides a system for determining the load factor of a wheel disc low-cycle fatigue test, comprising:

[0018] Finite element analysis module, used to obtain the stress spectrum σ of each key part of the wheel under the engine state through finite element analysis i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves;

[0019] The first model building module is used to build an equivalent stress basic model of the wheel disc material at each typical temperature based on stress ratio according to different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, and to obtain an equivalent stress analysis model at different temperatures using linear interpolation;

[0020] The second model building module is used to fit the fatigue life values at each typical temperature on the fatigue life curve of the wheel material and the equivalent stresses of different stress ratios at each typical temperature obtained according to the equivalent stress basic model to obtain a basic material life model between the equivalent stress and the fatigue life of the wheel material at typical temperatures, and to obtain a wheel life analysis model at different temperatures through log-linear interpolation;

[0021] The life analysis module is used to obtain the equivalent stress σ of each key part of the wheel under the engine state based on the temperature of each key part of the wheel under the engine state and the peak stress and valley stress in the stress spectrum using the equivalent stress analysis model at the corresponding temperature. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ;

[0022] The first equivalent stress analysis module is used to extract N i The minimum value N in i,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ;

[0023] The second equivalent stress analysis module is used to i,min As the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ;

[0024] Load factor analysis module is used to calculate the life span of each key part of the wheel according to the engine status. i Corresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i， use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

[0025] Furthermore, in the first model building module, the equivalent stress basic model is σ e =σ max (1-R) m , where σ e is the equivalent stress that comprehensively considers the influence of stress ratio R, where σ max is the peak stress, m is the wheel material constant determined by the test, the value range of m is 0.45-0.65, the stress ratio σ minis the valley stress.

[0026] Furthermore, in the second model building module, the equivalent stress σ e The basic model of material life between fatigue life N is lgN=AB·lgσ e , where A and B are obtained by data fitting.

[0027] To achieve the above technical effects, the present invention further provides an application of a method for determining a wheel disc low-cycle fatigue test load factor. The application is based on the low-cycle fatigue test load factor K of each key part of the wheel disc obtained by the method, and is characterized by comprising:

[0028] Carry out wheel fatigue test to obtain the number of test cycles N when crack length not less than the preset length appears on the surface of the key part of the wheel sy ;

[0029] According to the low cycle fatigue test load factor K of each key part of the wheel, Analyze and obtain the fatigue life N of each key part of the wheel under engine state fdj .

[0030] Furthermore, before conducting the wheel fatigue test, if the load coefficient K of the key part is less than 1.0, the test load should be increased and the wheel low-cycle fatigue test load coefficient should be re-analyzed until the wheel low-cycle fatigue test load coefficient is greater than or equal to 1.0 before conducting the wheel fatigue test.

[0031] Furthermore, the preset crack length is 0.76 mm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention constructs a life analysis model between the equivalent stress of the wheel material at typical temperatures and the fatigue life of the wheel material. Based on the stress characteristics and temperature characteristics of each key part of the wheel under the engine state, and by comprehensively considering the influence of the peak-to-valley stress ratio of the wheel under the working state on the fatigue life of the wheel and the change law of material properties with temperature, the load coefficient of the low-cycle fatigue test of the wheel is reasonably determined, thereby reducing the safety risks caused by the deviation of the load coefficient from the actual situation, making the design and use of the wheel safer and more reliable. By correcting the load coefficient, it is ensured that the fatigue damage under the engine state can be truly reflected under the test state.

[0034] 2. The wheel test life conversion method proposed in the present invention converts the theoretical fatigue life of each key part of the wheel under the engine state based on the low-cycle fatigue test load coefficient K of each key part of the wheel. This life conversion method combines the actual working state and fatigue characteristics of the wheel, thereby effectively determining the safe life of the wheel and providing support for the wheel life management. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of the method for determining the load factor of the wheel disc low-cycle fatigue test in Example 1;

[0036] Figure 2 This is a block diagram of the system structure for determining the load factor of the wheel disc low-cycle fatigue test in Example 1;

[0037] Figure 3 This is a flow chart of the application of the method for determining the load factor of a wheel disc low-cycle fatigue test in Example 2;

[0038] Among them, 1. Finite element analysis module; 2. First model construction module; 3. Second model construction module; 4. Life analysis module; 5. First equivalent stress analysis module; 6. Second equivalent stress analysis module; 7. Load coefficient analysis module. DETAILED DESCRIPTION

[0039] 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.

[0040] Example 1

[0041] See also Figure 1 and Figure 2 , a method for determining the load factor of a wheel disc low cycle fatigue test, including

[0042] Conduct finite element analysis of the wheel in the engine state and obtain the stress spectrum σ of each key part of the wheel i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves;

[0043] Based on the different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, a basic model of equivalent stress of the wheel disc material at each typical temperature based on stress ratio is constructed, and the equivalent stress analysis model at different temperatures is obtained by linear interpolation;

[0044] Based on the fatigue life values at each typical temperature on the fatigue life curve of the wheel material and the equivalent stresses of different stress ratios at each typical temperature obtained according to the equivalent stress basic model, a basic material life model between the equivalent stress at typical temperature and the fatigue life of the wheel material is fitted, and the wheel life analysis model at different temperatures is obtained through logarithmic linear interpolation;

[0045] According to the temperature of each key part of the wheel disc under the engine state and the peak stress and valley stress in the stress spectrum, the equivalent stress analysis model at the corresponding temperature is used to analyze and obtain the equivalent stress σ of each key part of the wheel disc under the engine state. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ;

[0046] Extract the N i The minimum value N in i,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ;

[0047] Take T i,min As the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ;

[0048] According to the engine status, the life of each key part of the wheel is N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i， use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

[0049] In this embodiment, a life analysis model is constructed between the equivalent stress of the wheel material at typical temperatures and the fatigue life of the wheel material. Based on the stress and temperature characteristics of each key part of the wheel in the engine state, the influence of the peak-to-valley stress ratio of the wheel in the working state on the fatigue life of the wheel is comprehensively considered. By converting the equivalent stress of the key parts of the wheel in the engine state at different temperatures into T i,min The equivalent stress at temperature takes into account the change of material properties with temperature, realizes the reasonable determination of the load factor of the low-cycle fatigue test of the wheel, reduces the safety risk caused by the deviation of the load factor from the actual one, and makes the design and use of the wheel safer and more reliable. By correcting the load factor, it ensures that the fatigue damage under the engine state can be truly reflected under the test state.

[0050] Based on the same inventive concept, this embodiment also provides a system for determining a load factor of a wheel disc low-cycle fatigue test, comprising:

[0051] Finite element analysis module 1 is used to obtain the stress spectrum σ of each key part of the wheel under the engine state through finite element analysis i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves;

[0052] The first model building module 2 is used to build an equivalent stress basic model of the wheel disc material at each typical temperature based on the stress ratio according to the different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, and to obtain an equivalent stress analysis model at different temperatures using linear interpolation;

[0053] The second model building module 3 is used to fit the fatigue life values at each typical temperature on the fatigue life curve of the disc material and the equivalent stresses of different stress ratios at each typical temperature obtained according to the equivalent stress basic model, to obtain a basic material life model between the equivalent stress and the fatigue life of the disc material at the typical temperature, and to obtain a disc life analysis model at different temperatures through log-linear interpolation;

[0054] Life analysis module 4 is used to obtain the equivalent stress σ of each key part of the wheel under the engine state according to the temperature of each key part of the wheel under the engine state and the peak stress and valley stress in the stress spectrum using the equivalent stress analysis model under the corresponding temperature. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ;

[0055] The first equivalent stress analysis module 5 is used to extract N i The minimum value N ini,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ;

[0056] The second equivalent stress analysis module 6 is used to calculate the stress of the i,min As the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ;

[0057] Load factor analysis module 7 is used to calculate the life span N of each key part of the wheel according to the engine status. i Corresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i， use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

[0058] Example 2

[0059] See also Figure 3 , an application of a method for determining the load factor of a wheel disc low cycle fatigue test, comprising:

[0060] Step 1: Conduct finite element analysis of the wheel in the engine state to obtain the stress spectrum σ of each key part of the wheel i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves;

[0061] Step 2: Based on the different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, a basic model of equivalent stress of the wheel disc material at each typical temperature based on stress ratio is constructed, and an equivalent stress analysis model at different temperatures is obtained by linear interpolation;

[0062] In this embodiment, the equivalent stress basic model is σ e =σ max(1-R) m , where σ e is the equivalent stress that comprehensively considers the influence of stress ratio R, where σ max is the peak stress, m is the wheel material constant determined by the test, the value range of m is 0.45-0.65, the stress ratio σ min The equivalent stress analysis model comprehensively considers the influence of the peak-to-valley stress ratio and can more accurately reflect the stress state of the wheel material during fatigue testing.

[0063] Step 3: Based on the fatigue life values at each typical temperature on the fatigue life curve of the wheel material and the equivalent stresses at different stress ratios at each typical temperature obtained based on the equivalent stress basic model, a basic material life model between the equivalent stress at typical temperature and the fatigue life of the wheel material is fitted, and a wheel life analysis model at different temperatures is obtained through log-linear interpolation.

[0064] In this embodiment, the equivalent stress σ e The basic model of material life between fatigue life N is lgN=AB·lgσ e , where A and B are obtained through data fitting. This life analysis model is based on test data fitting and takes into account the influence of valley stress. It can more accurately describe the fatigue life characteristics of the wheel material at different stress ratio levels and is conducive to the reasonable determination of the load factor for the low-cycle fatigue test of the wheel.

[0065] Step 4: Based on the temperature of each key part of the wheel disc under the engine state and the peak stress and valley stress in the stress spectrum, the equivalent stress analysis model at the corresponding temperature is used to analyze and obtain the equivalent stress σ of each key part of the wheel disc under the engine state. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ;

[0066] Step 5: Extract N under engine status i The minimum value N in i,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ;

[0067] Step 6: Take T i,minAs the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ;

[0068] Step 7: Calculate the life span (N) of each key part of the wheel according to the engine status i Corresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i ,use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

[0069] Step 8: Carry out fatigue test on the wheel disc to obtain the number of test cycles N when a crack of not less than the preset length appears on the surface of the key part of the wheel disc. sy ;

[0070] Step 9: According to the low cycle fatigue test load factor K of each key part of the wheel, use Analyze and obtain the fatigue life N of each key part of the wheel under engine state fdj .

[0071] The current method of inferring the engine life from disk fatigue test results using the relative linear damage theory fails to consider the effect of the load factor on damage, resulting in a potentially dangerously high calculated engine disk life, posing certain risks to engineering use. This embodiment uses the obtained low-cycle fatigue test load factor K of each key disk component to calculate the theoretical fatigue life of each key disk component under engine conditions. This life conversion method combines the actual operating conditions and fatigue characteristics of the disk to effectively determine the safe life of the disk, providing support for disk life management.

[0072] In this embodiment, the preset crack length is 0.76 mm. The preset crack lengths of other configurations of the wheel disc structure can be reasonably determined according to specific design requirements.

[0073] In some other embodiments, before conducting the wheel fatigue test, if the load factor K of the key part is less than 1.0, the test load is increased and the wheel low cycle fatigue test load factor is re-analyzed until the wheel low cycle fatigue test load factor is greater than or equal to 1.0 before conducting the wheel fatigue test. This can more reasonably simulate the fatigue life of the engine wheel.

[0074] 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 the load factor of a wheel disc low cycle fatigue test, characterized in that: include: Conduct finite element analysis of the wheel in the engine state and obtain the stress spectrum σ of each key part of the wheel i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves; Based on the different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, a basic model of equivalent stress of the wheel disc material at each typical temperature based on stress ratio is constructed, and the equivalent stress analysis model at different temperatures is obtained by linear interpolation; Based on the fatigue life values at each typical temperature on the fatigue life curve of the wheel material and the equivalent stresses of different stress ratios at each typical temperature obtained according to the equivalent stress basic model, a basic material life model between the equivalent stress at typical temperature and the fatigue life of the wheel material is fitted, and the wheel life analysis model at different temperatures is obtained through logarithmic linear interpolation; According to the temperature of each key part of the wheel disc under the engine state and the peak stress and valley stress in the stress spectrum, the equivalent stress analysis model at the corresponding temperature is used to analyze and obtain the equivalent stress σ of each key part of the wheel disc under the engine state. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ; Extract the N i The minimum value N in i,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ; Take T i,min As the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ; According to the engine status, the life of each key part of the wheel is N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i ,use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

2. The method for determining the load factor of a wheel disc low cycle fatigue test according to claim 1, characterized in that: The equivalent stress basic model is σ e =σ max (1-R) m , where σ e is the equivalent stress that comprehensively considers the influence of stress ratio R, where σ max is the peak stress, m is the wheel material constant determined by the test, the value range of m is 0.45-0.65, the stress ratio σ min is the valley stress.

3. The method for determining the load factor of a wheel disc low cycle fatigue test according to claim 1, characterized in that: Equivalent stress σ e The basic model of material life between fatigue life N is lgN=AB·lgσ e , where A and B are obtained by data fitting.

4. A system for determining load factors of a wheel disc low cycle fatigue test, characterized in that: include: Finite element analysis module, used to obtain the stress spectrum σ of each key part of the wheel under the engine state through finite element analysis i And the corresponding temperature spectrum T i , i = 1, 2, ..., n, where n is the number of key parts, including but not limited to the disk core, spoke rounding, bolt holes, and mortise and tenon grooves; The first model building module is used to build an equivalent stress basic model of the wheel disc material at each typical temperature based on stress ratio according to different peak stresses and valley stresses at typical temperatures in the fatigue performance data of the wheel disc material, and to obtain an equivalent stress analysis model at different temperatures using linear interpolation; The second model building module is used to fit the fatigue life values at each typical temperature on the fatigue life curve of the wheel material and the equivalent stresses of different stress ratios at each typical temperature obtained according to the equivalent stress basic model to obtain a basic material life model between the equivalent stress and the fatigue life of the wheel material at typical temperatures, and to obtain a wheel life analysis model at different temperatures through log-linear interpolation; The life analysis module is used to obtain the equivalent stress σ of each key part of the wheel under the engine state based on the temperature of each key part of the wheel under the engine state and the peak stress and valley stress in the stress spectrum using the equivalent stress analysis model at the corresponding temperature. ei , and according to the wheel life analysis model, the life of each key part of the wheel in the engine state is obtained N i ; The first equivalent stress analysis module is used to extract N i The minimum value N in i,min And the temperature T of the corresponding key parts i,min , the life of each key part of the wheel in the engine state N i Substitute T i,min The life analysis model of the wheel under temperature is used to obtain the life of each key part of the wheel N i Corresponding to T i,min Equivalent stress σ at temperature efdj,i ; The second equivalent stress analysis module is used to i,min As the test state temperature of the wheel, the peak stress σ of each key part of the wheel under the test state is obtained through simulation analysis at the test speed. symax,i and valley stress σ symin,i , using T i,min The equivalent stress analysis model under temperature is calculated to obtain the stress of each key part of the wheel under the test condition at temperature T i,min The equivalent stress σ under esy,i ; Load factor analysis module is used to calculate the life span of each key part of the wheel according to the engine status. i Corresponding to T i,min Equivalent stress σ at temperature efdj,i And the key parts of the wheel at temperature T under the test state i,min The equivalent stress σ under esy,i ,use The low cycle fatigue test load factor K of each key part of the wheel is obtained by analysis.

5. The wheel disc low cycle fatigue test load factor determination system according to claim 4, characterized in that: In the first model building module, the equivalent stress basic model is σ e =σ max (1-R) m , where σ e is the equivalent stress that comprehensively considers the influence of stress ratio R, where σ max is the peak stress, m is the wheel material constant determined by the test, the value range of m is 0.45-0.65, the stress ratio σ min is the valley stress.

6. The wheel disc low cycle fatigue test load factor determination system according to claim 4, characterized in that: In the second model building module, the equivalent stress σ e The basic model of material life between fatigue life N is lgN=AB·lgσ e , where A and B are obtained by data fitting.

7. An application of a method for determining a low-cycle fatigue test load factor of a wheel disc, wherein the low-cycle fatigue test load factor K of each key part of the wheel disc is obtained based on the method for determining a low-cycle fatigue test load factor of a wheel disc according to any one of claims 1 to 3, and wherein: include: Carry out wheel fatigue test to obtain the number of test cycles N when crack length not less than the preset length appears on the surface of the key part of the wheel sy ; According to the low cycle fatigue test load factor K of each key part of the wheel, Analyze and obtain the fatigue life N of each key part of the wheel under engine state fdj .

8. Application of the method for determining the load factor of a wheel disc low cycle fatigue test according to claim 7, characterized in that: Before conducting the wheel fatigue test, if the load factor K of the key parts is less than 1.0, the test load should be increased and the wheel low-cycle fatigue test load factor should be re-analyzed until the wheel low-cycle fatigue test load factor is greater than or equal to 1.0 before conducting the wheel fatigue test.

9. Application of the method for determining the load factor of a wheel disc low cycle fatigue test according to claim 7 or 8, characterized in that: The preset crack length is 0.76 mm.

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