A fatigue life analysis method for a disk-shaft integrated blade structure

Abstract

The present invention discloses a fatigue life analysis method for a disk-shaft integrated integral blade disk structure, the steps of which are: obtaining the dangerous parts, stress distribution and stress gradient distribution of the disk-shaft integrated integral blade disk structure by a simulation analysis method; performing fatigue tests on standard smooth specimens and standard notched specimens as well as static tensile tests on materials at room temperature and high temperature, and combining the simulation analysis results with an influencing factor correction method to obtain a material stress-fatigue life relationship that considers influencing factors such as average stress, stress gradient and temperature; and then accumulating fatigue damage by a structural fatigue life analysis method to obtain the fatigue life of the disk-shaft integrated integral blade disk structure. The present invention combines test results, simulation analysis and traditional fatigue analysis methods, which is simple and intuitive, with clear steps and strong applicability. The present invention can be used to ensure the life requirements of air turbine starters and aircraft engines, and provide a sufficient and scientific life assessment basis for the design and manufacture of similar complex working components.

Description

Technical Field

[0001] The present invention belongs to the technical field of fatigue life analysis of engineering structures, and in particular relates to a fatigue life analysis technology of a disk-shaft integrated integral blade disk structure, which provides a technical basis for fatigue damage analysis and fatigue life assessment of engineering machinery components under actual loads, and is an important step in the design and strength assessment of complex engineering structure parts under actual service loads. Background Art

[0002] The air turbine starter is an important component of the aircraft auxiliary power system. In terms of structural integrity and reliability, its safety will have an important impact on the overall safety performance of the aircraft engine. With the continuous development of aviation manufacturing technology, disc components have gradually adopted a disc-shaft integrated structure, that is, the disc body, blades and axle are processed and manufactured in one piece, which greatly simplifies the starter structure. Nowadays, with the rapid development of military and civil aviation engines, the power requirements for air turbine starters are getting higher and higher. As the key rotating component of the starter, the life of the turbine rotor limits the life of the entire air turbine starter. Therefore, in order to ensure the life requirements of air turbine starters and aircraft engines, it is necessary to conduct a full and scientific life assessment of this type of structure, and develop a fatigue life analysis technology for the disc-shaft integrated integral blade structure.

[0003] Air turbine starters are subjected to increasingly severe aerodynamic and mechanical loads, which places higher and higher requirements on the safety and reliability of their turbine blade disc structures. Fatigue fracture is the main cause of failure of engineering machinery components. Many scholars at home and abroad have conducted in-depth and systematic research on fatigue from the perspective of theory and experiment, from parts to complete equipment, and established a large number of fatigue life prediction methods and models. Wang Weiguo conducted a high-temperature low-cycle fatigue test on a full-size turbine disc and proposed an improved Walker strain life prediction model. However, it is difficult to test a full-size turbine disc in engineering practice, and the economic cost is high. Li Jun et al. and Du Wenjun et al. conducted fatigue life analysis on the turbine blade-tenon-disc structure and the compressor disc tenon-groove structure based on the Manson-Coffin equation, but they were unable to give a quantitative description of the influencing factors such as average stress, stress gradient, and temperature, and thus could not make an accurate analysis of the fatigue life of the structure or machinery.

[0004] In summary, the existing fatigue life analysis methods for impeller components still have certain limitations, and there is no generally recognized fatigue life analysis method for integrated disk-shaft integral blade disk structures that comprehensively considers factors such as average stress, stress gradient, and temperature. With the further maturity and application of integrated disk-shaft integral blade disk structures, the fatigue life verification of integrated disk-shaft integral blade disk structures is still a key engineering problem that urgently needs to be solved, which is also of great significance to the life analysis and structural integrity of impeller machinery such as aircraft engines and starters in engineering practice.

[0005] Therefore, it is necessary to develop an accurate, reasonable and engineering-friendly fatigue life analysis technology that comprehensively considers influencing factors such as average stress, stress gradient and temperature, so as to realize the fatigue life analysis of the integrated blade disk structure with integrated shaft and disk. Summary of the invention

[0006] In order to solve the problems of insufficient operability, accuracy and applicability of the fatigue life analysis engineering of the disk-shaft integrated integral blade disk in the prior art, the purpose of the present invention is to provide a fatigue life analysis method for the disk-shaft integrated integral blade disk structure, which can perform accurate and reasonable fatigue life analysis on the disk-shaft integrated integral blade disk.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A fatigue life analysis method for a disk-shaft integrated blisk structure comprises the following steps:

[0009] (1) Establish a three-dimensional model of the integrated blade disk structure and perform finite element stress-strain analysis to obtain the dangerous parts, stress distribution, and stress gradient distribution of the integrated blade disk structure;

[0010] (2) Conduct fatigue tests on standard smooth specimens of materials used in the integrated disk-shaft structure to obtain the stress ratio-stress amplitude-fatigue life relationship of the corresponding materials, perform average stress correction on general loads and fatigue life, and obtain the stress amplitude-stress mean-fatigue life relationship;

[0011] (3) conducting a standard notch specimen fatigue test on the material used for the disk-shaft integrated integral blade disk structure to obtain the notch coefficient-stress-fatigue life relationship of the corresponding material, combining the stress gradient distribution obtained in step (1), performing stress gradient correction on the stress amplitude-stress mean-fatigue life relationship obtained in step (2), and obtaining the stress amplitude-stress mean-stress gradient-fatigue life relationship;

[0012] (4) Conducting static tensile tests of standard specimens at room temperature and high temperature on the materials used for the disk-shaft integrated integral blade disk structure. Based on the test results, the stress amplitude-stress mean-stress gradient-fatigue life relationship obtained in step (3) is subjected to temperature correction to obtain a material stress-fatigue life relationship that comprehensively considers the effects of mean stress, stress gradient and temperature;

[0013] (5) Based on the material stress-fatigue life relationship obtained in step (4), fatigue damage accumulation is performed in combination with the component fatigue life analysis method to obtain the fatigue life of the integrated disk-shaft integral blade disk structure.

[0014] The specific steps of step (1) are:

[0015] (11) Establish a three-dimensional model of the integrated disk-shaft structure and perform finite element analysis on the model using ANSYS finite element software, including: ① assigning material properties and unit types, ② component modeling and meshing, and ③ stress-strain data analysis;

[0016] (12) Based on the finite element analysis results of step (11), the dangerous parts of the overall blade disk structure are determined, and the coordinate data and stress-strain data of the nodes in a small range near the dangerous parts are extracted, and the stress gradient at the dangerous point is calculated according to the following formula;

[0017]

[0018] Among them, σ ij is the stress tensor, x k is the length in the k direction, and i, j, k represent the directions of the coordinate system.

[0019] The specific steps of step (2) are:

[0020] (21) Conduct stress fatigue life tests on standard smooth test pieces of blade disk materials at different stress ratios. Conduct fatigue life tests at three stress levels at each stress ratio. Conduct three tests at each stress level and take the average value as the fatigue life corresponding to this stress level.

[0021] (22) The test results were fitted to obtain the stress amplitude-fatigue life relationship under different stress ratios:

[0022] f(R,S,N f )=0

[0023] Where R is the stress ratio, S is the stress amplitude, N f is the fatigue life;

[0024] (23) According to the material stress-fatigue life relationship obtained from the data fitting result of step (22), the material iso-life curve is drawn, and the average stress correction is performed on the general load and fatigue life according to the iso-life curve to obtain the stress amplitude-stress mean-fatigue life relationship:

[0025] f(S a ,S m ,N f )=0

[0026] Among them, S a is the stress amplitude, S m is the mean stress, N f is the fatigue life.

[0027] The specific steps of step (3) are:

[0028] (31) Conduct stress fatigue life tests on standard notch test pieces of blade disk materials at different stress ratios, and conduct fatigue life tests on standard notch test pieces with different notch coefficients at each stress ratio. Three stress level fatigue life tests are conducted respectively, and three tests are conducted at each stress level. The average value is taken as the fatigue life corresponding to this stress level. Based on the test results, the material stress-fatigue life relationship of different notch coefficients at different stress ratios is obtained;

[0029] (32) The test results were fitted to obtain the relationship between notch factor, stress amplitude and fatigue life under different stress ratios:

[0030] f(K t ,S a ,S m ,N f )=0

[0031] Among them, K t is the notch factor, S a is the stress amplitude, S m is the mean stress, N f is the fatigue life;

[0032] (33) Introducing the stress gradient influence coefficient α and the stress gradient influence exponent β, and performing stress gradient correction on the blade disk material stress-fatigue life curve obtained in step (2) according to the test results obtained in step (31) and step (32):

[0033] S a =α·S′ a β , N f =N′ f

[0034] Among them, S a and S′a They are respectively the fatigue life of the standard smooth test piece N f and the maximum stress gradient interpolated from the fatigue life of the standard notched test piece is η max Fatigue life N′ f The stress amplitude under

[0035] Thus, the stress amplitude-average stress-stress gradient-fatigue life relationship is obtained;

[0036] f(S a ,S m ,α,β,η max ,N f )=0

[0037] Among them, S a is the stress amplitude, S m is the stress mean, α is the stress gradient influence coefficient, β is the stress gradient influence index, η max is the maximum stress gradient, N f is the fatigue life.

[0038] The specific steps of step (4) are:

[0039] (41) Static tensile tests were carried out on the materials used for the integrated disk-shaft blade under normal temperature and high temperature conditions, and the stress-strain relationship curves of the materials at the two temperatures were obtained;

[0040] (42) By comparing the tensile stress-strain curves of the material at two temperatures, the temperature correction coefficient μ and the temperature correction exponent ν are introduced to perform temperature correction on the stress amplitude-average stress-stress gradient-fatigue life relationship obtained in step (3):

[0041] S a =μ·S′ a ν , ε a =ε′ a

[0042] Among them, S a and S′ a The same strain amplitude ε of standard smooth test pieces at room temperature and high temperature a ,ε′ a The stress amplitude under

[0043] Thus, the material stress-fatigue life relationship considering the influence of average stress, stress gradient and temperature is obtained:

[0044] f(S a ,S m ,α,β,η max ,μ,ν,N f )=0

[0045] Among them, S a is the stress amplitude, S m is the stress mean, α is the stress gradient influence coefficient, β is the stress gradient influence index, η max is the maximum stress gradient, μ is the temperature correction coefficient, ν is the temperature correction index, N f is the fatigue life.

[0046] The specific steps of step (5) are:

[0047] According to the stress of the dangerous part of the disk-shaft integrated integral blade disk structure obtained in step (1) and the material stress-fatigue life relationship obtained in step (4) that comprehensively considers the average stress, stress gradient and temperature effects, the fatigue life of the disk-shaft integrated integral blade disk is obtained by calculation and analysis using the linear fatigue damage accumulation theory through the following formula:

[0048]

[0049] Where D cr represents the critical damage of the integrated disk-shaft blade structure; N represents the total fatigue life of the integrated disk-shaft blade structure; n i and N i It is the number of a certain type of load cycles and the fatigue life of this type of cycle.

[0050] Beneficial effects: The present invention obtains the dangerous parts, stress analysis results and stress gradient analysis results of the integrated blade disk structure based on finite element simulation analysis; combined with the finite element simulation analysis results, the standard specimen fatigue test is used to obtain the material stress-fatigue life relationship that comprehensively considers the average stress, stress gradient and temperature effects. Using the finite element simulation analysis results and the corrected material stress-fatigue life relationship, the fatigue life of the integrated blade disk with a shaft is calculated and analyzed through the component fatigue life analysis method. Compared with the prior art, the advantages are:

[0051] (1) Simple and intuitive, with clear steps and strong applicability;

[0052] Based on the standard sample test of the blade disk material, the material stress-fatigue life relationship is combined with the simulation analysis results to obtain the material stress-fatigue life relationship that takes into account the average stress, stress gradient and temperature factors. The fatigue life of the integrated blade disk with integrated shaft is obtained by calculation and analysis using the linear fatigue damage accumulation theory. Compared with the existing engine disk structure fatigue life analysis technology, the test cost of the present invention is greatly reduced, and combined with the simulation analysis results, while ensuring accuracy, the calculation steps are clear and simple, which can reduce the design and development costs and time.

[0053] (2) It has extensive engineering application value;

[0054] The fatigue life analysis technology of the integrated disk-shaft integral blade disk structure proposed in the present invention has strong versatility. Therefore, with the further maturity and application of the integrated disk-shaft structure and the integral blade disk structure, under the existing technical conditions, the fatigue life of the integrated disk-shaft integral blade disk can be reasonably calculated accurately and quickly by using the present invention, which has wide engineering application value.

[0055] In summary, the present invention combines test results, simulation analysis and traditional fatigue analysis methods, which is simple and intuitive, with clear steps and strong applicability. The present invention can ensure the life requirements of air turbine starters and aircraft engines, and provide sufficient and scientific life assessment basis for the design and manufacture of similar complex working components. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is the specific technical roadmap of the present invention;

[0057] Figure 2 It is a schematic diagram of stress-fatigue life of the standard smooth test piece of this example under different stress ratios;

[0058] Figure 3 This is a schematic diagram of the iso-life curve of the standard smooth test piece in this example;

[0059] Figure 4 This is the stress-fatigue life curve of the standard notch test piece in this example at different stress ratios;

[0060] Figure 5 This is a schematic diagram of the gradient correction of the stress-fatigue life relationship in this example;

[0061] Figure 6 This is a schematic diagram of the temperature correction of the stress-fatigue life relationship in this example. DETAILED DESCRIPTION

[0062] The present invention will be further explained below in conjunction with the accompanying drawings.

[0063] A fatigue life analysis technology for a disk-shaft integrated integral blade disk structure of the present invention obtains the dangerous parts, stress distribution and stress gradient distribution of the disk-shaft integrated integral blade disk structure through a simulation analysis method; fatigue tests on standard smooth specimens and standard notched specimens, as well as static tensile tests on materials at room temperature and high temperature are carried out, and the material stress-fatigue life relationship considering the influencing factors such as average stress, stress gradient and temperature is obtained by combining the simulation analysis results and the influencing factor correction method; fatigue damage accumulation is then carried out through a structural fatigue life analysis method to obtain the fatigue life of the disk-shaft integrated integral blade disk structure.

[0064] The present invention is further described below in conjunction with the embodiments and drawings. The specific implementation steps are as follows:

[0065] The present invention is now analyzed using a turbine rotor component of a certain type of air turbine starter. Figure 1 , the steps are:

[0066] (1) Establish a three-dimensional model of the integrated blade disk structure with a shaft and perform finite element stress-strain analysis to obtain the dangerous parts, stress distribution, and stress gradient distribution of the integrated blade disk structure with a shaft; specifically:

[0067] (11) Establish a three-dimensional model of the integrated disk-shaft integral blade structure, that is, the turbine rotor component, and use ANSYS finite element software to perform finite element analysis on the model, including: ① assigning material properties and unit types, ② component modeling and meshing, and ③ stress and strain data analysis;

[0068] (12) Based on the finite element analysis results of step (11), the dangerous parts of the overall blade disk structure are determined, and the coordinate data and stress-strain data of the nodes in a small range near the dangerous parts are extracted, and the stress gradient at the dangerous point is calculated according to the following formula;

[0069]

[0070] Among them, σ ij is the stress tensor, x k is the length in the k direction, and i, j, k represent the directions of the coordinate system.

[0071] (2) Conduct fatigue tests on standard smooth specimens of materials used in the integrated disk-shaft blade structure to obtain the stress ratio-stress amplitude-fatigue life relationship of the corresponding materials, perform average stress correction on general loads and fatigue life, and obtain the stress amplitude-stress mean-fatigue life relationship; the steps are:

[0072] (21) Stress fatigue life tests were carried out on standard smooth test pieces of blade disk materials at stress ratios R = 0 and R = 0.5. Three stress level fatigue life tests were carried out at each stress ratio, namely S 0,1 ,S 0,2 ,S 0,3 and S 0.5,1 ,S 0.5,2 ,S 0.5,3 , three tests are carried out for each stress level, and the average value is taken as the life corresponding to this stress level, that is, N 0,1 ,N 0,2 ,N 0,3 and N 0.5,1 ,N 0.5,2 ,N 0.5,3 .

[0073] (22) The Basquin formula was used to fit the test results, as follows: Figure 2 According to the test results, the stress amplitude-fatigue life relationship under stress ratio R=0 and R=0.5 is obtained:

[0074]

[0075] Where R is the stress ratio, S is the stress amplitude, N f is the fatigue life, A1, B1, A2, B2 are the fitting coefficients.

[0076] (23) Based on the material stress-fatigue life relationship obtained from the fitting results, the material life curve is drawn, such as Figure 3 According to the equal life curve, the average stress correction is performed on the general load and fatigue life to obtain the relationship between stress amplitude, average stress and fatigue life:

[0077] N f =f(S a ,S m )

[0078] Among them, S a is the stress ratio, S m is the stress amplitude, N f is the fatigue life.

[0079] (3) Conducting a standard notch specimen fatigue test on the material used for the disk-shaft integrated integral blade disk structure to obtain the notch coefficient-stress-fatigue life relationship of the corresponding material, combining the stress gradient distribution obtained in step (1), performing stress gradient correction on the stress amplitude-stress mean-fatigue life relationship obtained in step (2), and obtaining the stress amplitude-stress mean-stress gradient-fatigue life relationship; the steps are:

[0080] (31) Stress fatigue life tests were carried out on standard notched test pieces of blade disk materials at stress ratios R = 0 and R = 0.5. The notch coefficient K was tested at each stress ratio. t =2, K t =3 standard notch test piece fatigue life test, in which three stress level fatigue life tests were carried out respectively, and three tests were carried out for each stress level, namely S 0,2,1 ,S 0,2,2 ,S 0,2,3 , S 0,3,1 ,S 0,3,2 ,S 0,3,3 , S 0.5,3,1 ,S 0.5,3,2 ,S 0.5,3,3 and S 0.5,3,1 ,S 0.5,3,2 ,S 0.5,3,3 , take the average value as the life corresponding to this stress level, that is, N0,2,1 ,N 0,2,2 ,N 0,2,3 、N 0,3,1 ,N 0,3,2 ,N 0,3,3 、N 0.5,3,1 ,N 0.5,3,2 ,N 0.5,3,3 and N 0.5,3,1 ,N 0.5,3,2 ,N 0.5,3,3 , where the subscripts represent stress ratio, notch factor and stress level respectively.

[0081] (32) The Basquin formula was used to fit the experimental results, as follows: Figure 4 According to the test results, the relationship between notch factor, stress amplitude and fatigue life under different stress ratios is obtained:

[0082] N f =f(K t ,S a ,S m )

[0083] Among them, K t is the notch factor, S a is the stress amplitude, S m is the mean stress, N f is the fatigue life.

[0084] (33) Introducing the stress gradient influence coefficient α and the stress gradient influence exponent β, according to the test results obtained in step (31) and step (32), the stress gradient correction is performed on the blade material stress-fatigue life curve after the average stress correction in step (2), such as Figure 5 .

[0085] S a =α·S′ a β , N f =N′ f

[0086] Among them, S a and S′ a They are respectively the fatigue life of the standard smooth test piece N f and the maximum stress gradient interpolated from the fatigue life of the standard notched test piece is η max Fatigue life N′ f The stress amplitude below.

[0087] Thus, the stress amplitude-average stress-stress gradient-fatigue life relationship can be obtained;

[0088] N f =f(S a ,S m,α,β,η max )

[0089] Among them, S a is the stress amplitude, S m is the stress mean, α is the stress gradient influence coefficient, β is the stress gradient influence index, η max is the maximum stress gradient, N f is the fatigue life.

[0090] (4) Conduct static tensile tests of standard specimens at room temperature and high temperature on the materials used for the disk-shaft integrated blade disk structure. Combined with the test results, perform temperature correction on the stress amplitude-stress mean-stress gradient-fatigue life relationship obtained in step (3) to obtain a material stress-fatigue life relationship that comprehensively considers the effects of mean stress, stress gradient and temperature; specifically:

[0091] (41) Static tensile tests were carried out on the materials used for the integrated disk-shaft blade under normal temperature and high temperature conditions, and the stress-strain relationship curves of the materials at the two temperatures were obtained;

[0092] (42) By comparing the tensile stress-strain curves of the material at two temperatures, the temperature correction coefficient μ and the temperature correction exponent ν are introduced to perform temperature correction on the stress amplitude-average stress-stress gradient-fatigue life relationship obtained in step (3), as follows: Figure 6 .

[0093] S a =μ·S a ' ν , ε a =ε′ a

[0094] Among them, S a and S′ a The same strain amplitude ε of standard smooth test pieces at room temperature and high temperature a ,ε′ a The stress amplitude below.

[0095] Thus, the material stress-fatigue life relationship that comprehensively considers the effects of mean stress, stress gradient and temperature can be obtained;

[0096] N f =f(S a ,S m ,α,β,η max ,μ,ν)

[0097] Among them, S a is the stress amplitude, S m is the stress mean, α is the stress gradient influence coefficient, β is the stress gradient influence index, η maxis the maximum stress gradient calculated in step (1), μ is the temperature correction coefficient, ν is the temperature correction exponent, N f is the fatigue life.

[0098] (5) Based on the material stress-fatigue life relationship obtained in step (4), fatigue damage accumulation is performed in combination with a component fatigue life analysis method to obtain the fatigue life of the disk-shaft integrated integral blade disk structure; specifically:

[0099] According to the stress of the dangerous part of the blade disk obtained in step (1) and the material stress-fatigue life relationship obtained in step (4) that comprehensively considers the average stress, stress gradient and temperature effects, the fatigue life of the integrated blade disk with integrated shaft is calculated and analyzed using the linear fatigue damage accumulation theory. Therefore, the calculation formula for the life of the integrated blade disk with integrated shaft is:

[0100]

[0101] Where D cr represents the critical damage of the integrated disk-shaft blade structure; N represents the total fatigue life of the integrated disk-shaft blade structure; n i and N i It is the number of a certain type of load cycles and the fatigue life of this type of cycle.

[0102] Therefore, the fatigue life calculation results of the integrated disk-shaft blade structure are shown in Table 1. It can be seen that the total damage of the integrated disk-shaft blade structure in the whole life cycle is less than the critical damage D cr =1, meeting the life assessment requirements.

[0103] Table 1

[0104]

[0105] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A fatigue life analysis method for a disk-shaft integrated blade disk structure, characterized in that: The following steps are involved: (1) Establish a three-dimensional model of the integrated blade disk structure with a shaft and perform finite element stress-strain analysis to obtain the dangerous parts, stress distribution, and stress gradient distribution of the integrated blade disk structure with a shaft; the specific steps are as follows: (11) Establish a three-dimensional model of the integrated disk-shaft structure and perform finite element analysis on the model using ANSYS finite element software, including: ① assigning material properties and unit types, ② component modeling and meshing, and ③ stress-strain data analysis; (12) Based on the finite element analysis results of step (11), the dangerous parts of the overall blade disk structure are determined, and the coordinate data and stress-strain data of the nodes in a small range near the dangerous parts are extracted, and the stress gradient at the dangerous point is calculated according to the following formula; Among them, σ ij is the stress tensor, x k is the length in the k direction, i, j, k represent the directions of the coordinate system; (2) Conduct fatigue tests on standard smooth specimens of materials used in the disk-shaft integrated blade structure to obtain the stress ratio-stress amplitude-fatigue life relationship of the corresponding materials, perform average stress correction on general loads and fatigue life, and obtain the stress amplitude-stress mean-fatigue life relationship; the specific steps are: (21) Conduct stress fatigue life tests on standard smooth test pieces of blade disk materials at different stress ratios. Conduct fatigue life tests at three stress levels at each stress ratio. Conduct three tests at each stress level and take the average value as the fatigue life corresponding to this stress level. (22) The test results were fitted to obtain the stress amplitude-fatigue life relationship under different stress ratios: f(R,S,N f )=0 Where R is the stress ratio, S is the stress amplitude, N f is the fatigue life; (23) According to the material stress-fatigue life relationship obtained from the data fitting result of step (22), the material iso-life curve is drawn, and the average stress correction is performed on the general load and fatigue life according to the iso-life curve to obtain the stress amplitude-stress mean-fatigue life relationship: f(S a ,S m ,N f )=0 Among them, S a is the stress amplitude, S m is the mean stress, N f is the fatigue life; (3) Conducting a standard notch specimen fatigue test on the material used for the disk-shaft integrated blade disk structure to obtain the notch coefficient-stress-fatigue life relationship of the corresponding material, combining the stress gradient distribution obtained in step (1), performing stress gradient correction on the stress amplitude-stress mean-fatigue life relationship obtained in step (2), and obtaining the stress amplitude-stress mean-stress gradient-fatigue life relationship; the specific steps are: (31) Conduct stress fatigue life tests on standard notch test pieces of blade disk materials at different stress ratios, and conduct fatigue life tests on standard notch test pieces with different notch coefficients at each stress ratio. Three stress level fatigue life tests are conducted respectively, and three tests are conducted at each stress level. The average value is taken as the fatigue life corresponding to this stress level. Based on the test results, the material stress-fatigue life relationship of different notch coefficients at different stress ratios is obtained; (32) The test results were fitted to obtain the relationship between notch factor, stress amplitude and fatigue life under different stress ratios: f(K t ,S a ,S m ,N f )=0 Among them, K t is the notch factor, S a is the stress amplitude, S m is the mean stress, N f is the fatigue life; (33) Introducing the stress gradient influence coefficient α and the stress gradient influence exponent β, and performing stress gradient correction on the blade disk material stress-fatigue life curve obtained in step (2) according to the test results obtained in step (31) and step (32): Among them, S a and S a ′ are respectively the fatigue life of the standard smooth test piece N f and the maximum stress gradient interpolated from the fatigue life of the standard notched test piece is η max Fatigue life N′ f The stress amplitude under Thus, the stress amplitude-average stress-stress gradient-fatigue life relationship is obtained; f(S a ,S m ,a,b,h max ,N f )=0 Among them, S a is the stress amplitude, S m is the stress mean, α is the stress gradient influence coefficient, β is the stress gradient influence index, η max is the maximum stress gradient, N f is the fatigue life; (4) Conduct static tensile tests of standard specimens at room temperature and high temperature on the materials used for the disk-shaft integrated integral blade disk structure. Combined with the test results, perform temperature correction on the stress amplitude-stress mean-stress gradient-fatigue life relationship obtained in step (3) to obtain a material stress-fatigue life relationship that comprehensively considers the effects of mean stress, stress gradient and temperature. The specific steps are as follows: (41) Static tensile tests were carried out on the materials used for the integrated disk-shaft blade under normal temperature and high temperature conditions, and the stress-strain relationship curves of the materials at the two temperatures were obtained; (42) By comparing the tensile stress-strain curves of the material at two temperatures, the temperature correction coefficient μ and the temperature correction exponent ν are introduced to perform temperature correction on the stress amplitude-average stress-stress gradient-fatigue life relationship obtained in step (3): Among them, S a and S a ′ are the same strain amplitudes of standard smooth test pieces at room temperature and high temperature, respectively. a ,ε a Stress amplitude under ′; Thus, the material stress-fatigue life relationship considering the influence of average stress, stress gradient and temperature is obtained: f(S a ,S m ,a,b,h max ,m,n,N f )=0 Among them, S a is the stress amplitude, S m is the stress mean, α is the stress gradient influence coefficient, β is the stress gradient influence index, η max is the maximum stress gradient, μ is the temperature correction coefficient, ν is the temperature correction index, N f is the fatigue life; (5) Based on the material stress-fatigue life relationship obtained in step (4), fatigue damage accumulation is performed in combination with the component fatigue life analysis method to obtain the fatigue life of the integrated disk-shaft integral blade disk structure.

2. The fatigue life analysis method of the disk-shaft integrated blisk structure according to claim 1 is characterized by: The specific steps of step (5) are: According to the stress of the dangerous part of the disk-shaft integrated integral blade disk structure obtained in step (1) and the material stress-fatigue life relationship obtained in step (4) that comprehensively considers the average stress, stress gradient and temperature effects, the fatigue life of the disk-shaft integrated integral blade disk is obtained by calculation and analysis using the linear fatigue damage accumulation theory through the following formula: Where D cr represents the critical damage of the integrated disk-shaft blade structure; N represents the total fatigue life of the integrated disk-shaft blade structure; n i and N i It is the number of a certain type of load cycles and the fatigue life of this type of cycle.

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