Engine rotor and stator blade structural member equal-life design method based on isochronous stress-strain relation

Abstract

The invention discloses an equal-life design method for an engine rotor and stator blade structural member based on an isochronous stress-strain relationship, which is suitable for creep / endurance life design of the engine rotor and stator blade structural member. Acquiring a tensile stress-strain curve and a creep curve of the material at different temperatures and stresses; according to the target design life of the engine, extracting a stress-creep strain relation at the target life moment from the creep curve, and superposing the stress-creep strain relation with the tensile stress-strain curve to construct an isochronous stress-strain relation under the target life; inputting the isochronous stress-strain relationship into a rotor and stator blade finite element model, and calculating stress-strain distribution at a target life moment; and based on the comparison of the calculation result and the failure criterion, carrying out the weight reduction or local thickening optimization design of the blade until the target life requirement is met. The life prediction precision can be improved, the calculation cost is reduced, and the method has important engineering application value.

Description

Technical Field

[0001] The present invention belongs to the field of creep / endurance life design of aero-engines, and relates to an equal-life design method for structural components of engine stator and rotor blades. Specifically, it relates to an equal-life design method for structural components of engine stator and rotor blades based on the isochronous stress-strain relationship, which can quickly and reliably achieve the equal-life design of compressor and turbine stator and rotor blades according to the target design life, thereby contributing to the high cost-effectiveness design of aero-engines. Background Art

[0002] The compressor and the turbine are two key components indispensable in a low-cost and short-life engine. Compared with the turbine, the compressor has a lower temperature and is a cold-end component. However, compared with the compressor material, the compressor temperature is not low. Especially when the local stress of the compressor in a short-life engine is too large, the fracture problem caused by creep will become prominent. The turbine is a high-temperature component in the engine. As is well known, it has a very prominent endurance life caused by high-temperature creep. Specifically for a short-life engine, its characteristic is that the relatively short-time creep fracture characteristic under high temperature and large stress is different from the long-time creep / endurance life characteristic of a long-life engine. Therefore, studying the equal-life design method for structural components of compressor and turbine stator and rotor blades in a short-life engine to reduce the redundant design of blade life, lower the engine cost, and improve the high cost-effectiveness of the engine has important engineering value and practical significance. At the same time, it can also lay a foundation for the research and construction of a design system for high-performance, low-cost, and short-life engines.

[0003] During the research process of the equal-life design method, creep fracture life (i.e., endurance life) analysis needs to be carried out. At present, the macroscopic creep fracture life analysis methods are mainly divided into two categories. One is the prediction method based on endurance life tests, which predicts the structural endurance life through the endurance life data of standard specimens at corresponding temperatures and stresses, and is very convenient for engineering applications. Among these methods, the time-temperature parameter method has been developed most widely, and common methods include the L-M method, the G-D method, the M-S method, the M-H method, etc., which are the mainstream evaluation methods for engineering materials at present. However, this type of method has an inherent accuracy defect because it does not consider the specific creep process of the component; the endurance life of the structure under local stress is evaluated through the endurance life data of standard specimens with the average stress at the same temperature, making the life prediction conservative; at the same time, there are also many usage defects, including that the maximum stress cannot exceed 0.9 times the yield strength, the extrapolation time is short, and the prediction at low temperature and high stress is inaccurate, etc.

[0004] The other is the prediction method based on creep curves. θThe parametric method was first proposed and is suitable for materials where the second stage of creep is not obvious; various improved methods have been derived based on the different creep laws of the materials. Compared with the previous methods, the prediction method based on the creep curve has higher life reliability, but not every material conforms to the above laws. The conventional creep analysis method based on the creep curve simulates the creep of the structure based on the transient time analysis step. Since creep changes with time, a large number of iterative solutions are usually required during the analysis process. This method is relatively cumbersome, usually difficult to converge, and time-consuming. Stress concentration caused by the large number of small features or structural discontinuities in the blade will also have a significant impact on the simulation effect.

[0005] In summary, existing life prediction methods for compressor and turbine rotor blades still suffer from drawbacks and shortcomings in short-life, high-stress environments, including high computational complexity, conservative lifespan design, and a lack of rapid optimization methods. Therefore, developing a lifespan design method for rotor blades that balances high precision, high efficiency, and engineering applicability for short-life engine applications is a pressing technical challenge in the field of aero-engine structural lifespan design. Summary of the Invention

[0006] (1) Purpose of the invention In response to the technical deficiencies in the prior art, the present invention addresses technical issues in the creep fracture life design process for existing high-stress, short-life aero-engine rotor and stator blade structures, such as the existence of redundant compressor life, the conservative and inaccurate nature of commonly used engineering design methods, and the time-consuming and unstable nature of traditional creep analysis methods. A method for designing engine rotor and stator blade structures based on an isochronous stress-strain relationship is proposed. This method equates the creep deformation of the material to plastic deformation, constructs an isochronous stress-strain relationship for the target design life, and inputs this relationship into a finite element model of the rotor and stator blade structure to simulate the stress-strain distribution at the target life. By comparing the calculated results with the failure criteria, the blade design is optimized, achieving a life-span design for the engine rotor and stator blade structure. The present invention effectively addresses the issue of redundant compressor rotor blade life and enables rotor blades to be designed according to a specified target life, thereby effectively reducing weight and improving performance, directly contributing to the cost-effective design of aero-engines.

[0007] (II) Technical solution In order to achieve the purpose of the invention and solve the technical problems, the present invention adopts the following technical solutions: A method for designing the lifespan of an engine rotor and stator blade structure based on an isochronous stress-strain relationship is provided, which is used for designing the lifespan of compressor or turbine rotor and stator blades in high-stress, short-life aero-engines. The method comprises at least the following steps: SS1. Tensile test data acquisition: Under different temperature conditions, tensile tests will be conducted on the materials of the engine rotor-stator blade structural components to obtain their tensile stress-strain curves at different temperatures, so as to characterize the basic mechanical properties of the rotor-stator blade structural components; SS2. Obtaining creep test data: Under different temperatures and stresses, creep fracture tests will be conducted on the materials of the engine rotor-stator blade structural components to obtain their creep curves at different temperatures and stresses, so as to characterize the creep strain characteristics of the rotor-stator blade structural components at different life moments; SS3. Extracting creep strain data at target life: According to the target design life of the engine, extract the creep strain data under different stresses corresponding to the target design life moment from the creep curve to obtain the stress-creep strain relationship at the target design life; SS4. Constructing isochronous stress-strain relationship at target life: Superimpose the stress-creep strain relationship at the target design life and the tensile stress-strain curves at different temperatures to obtain the isochronous stress-strain relationship at the target design life, including the isochronous equivalent stress-equivalent total strain relationship or the isochronous equivalent stress-plastic total strain relationship; SS5. Finite element analysis based on the isochronous stress-strain relationship: Input the isochronous stress-strain relationships of the materials at different temperatures at the target design life moment into the finite element model of the engine rotor-stator blade structural components, and combine the loads and boundary conditions under the engine working conditions to calculate and determine the stress and strain distributions of the rotor-stator blade structural components at the target design life moment; SS6. Optimal design of the engine rotor-stator blade structural components: Based on the finite element calculation results, compare the calculated results of the stress and strain distributions at the life weak parts of the rotor-stator blade structural components at the target life moment with the preset failure criterion: if it is less than the failure criterion, carry out weight reduction optimization design of the blade and iterate until it approaches the failure criterion; if it is greater than the failure criterion, locally thicken or optimize the structure of the blade failure part and iterate until it does not exceed the failure criterion.

[0008] (III) Technical effects Compared with the existing technology, the equal-life design method of the engine rotor-stator blade structural components based on the isochronous stress-strain relationship of the present invention has the following beneficial and remarkable technical effects: (1) The isochronous life design of the compressor and turbine rotors proposed by the present invention realizes precise life prediction and optimal matching of the compressor and turbine stator and rotor blades through the modeling and calculation of the isochronous stress-strain relationship at the target life, enabling them to reach the design life synchronously within the target life range, improving the overall performance of the engine, reducing material waste, optimizing the structural weight, solving the problem of redundant life in the compressor, and facilitating the design of engines with high cost-effectiveness.

[0009] (2) The isochronous life design method based on the isochronous stress-strain relationship proposed by the present invention converts the creep calculation related to time into a static analysis problem by equivalent plastic deformation of creep deformation and constructing an elastic-plastic-creep constitutive relationship. Functionally, it can realize the design of the structure according to the specified target life. In terms of computational efficiency, compared with the creep analysis method, it can save the cumbersome process of creep calculation, greatly reduce the computational cost while meeting the requirements of engineering applications, and accelerate the design efficiency.

[0010] (3) The failure criterion proposed by the present invention determines the structural failure strain by combining the creep fracture test data of the simulated blade structural components, ensuring the accuracy and reliability of the failure criterion. Compared with the commonly used creep life analysis method in current engineering, it avoids the problem of inaccurate prediction under low-temperature and high-stress conditions, and can greatly improve the accuracy and reliability of life prediction.

[0011] (4) The design method of the present invention is simple and effective, can quickly iterate to realize the life optimization and weight reduction design of the stator and rotor blade structural components, is very suitable for engineering design and application, has a wide range of applications, and can be used for the creep / creep life design of the stator and rotor blades of aeroengines and gas turbines, including but not limited to the stator and rotor blades of fans / compressors, diffuser blades, turbine guide vanes, turbine rotor blades, and casing support plates, etc. Description of the Drawings

[0012] Figure 1 is the flowchart of the isochronous life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship in the embodiment of the present invention; Figure 2 is the isochronous stress-plastic strain curve of the compressor rotor material 2A70; Figure 3 is the isochronous stress-plastic strain curve of the turbine rotor material K424; Figure 4 is the equivalent total strain contour nephogram of the compressor rotor blade at 50h; Figure 5 is the equivalent total strain contour nephogram of the turbine rotor blade at 50h; Figure 6 is the model diagram of the compressor rotor blade before and after weight reduction; Figure 7 Model diagram of turbine rotor blades before and after weight reduction. DETAILED DESCRIPTION

[0013] The present invention proposes a method for isochronous stress-strain relationship-based design of the life span of an engine rotor and stator blade structure. To make the purpose, technical solution, characteristics, and engineering practicality of the present invention clearer, the technical solution in the embodiment of the present invention will be described in more detail below in conjunction with the accompanying drawings in the embodiment of the present invention. The described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be understood as limiting the present invention.

[0014] Example 1: Equal life design method As a specific example, Figure 1 As shown, the engine rotor and stator blade structural component equal life design method based on isochronous stress-strain relationship of the present invention is used for equal life design of compressor and turbine rotor and stator blade structural components of high stress and short life aircraft engines. The method comprises the following steps: SS1. Tensile test data acquisition: Under different temperature conditions, tensile tests will be carried out on the engine rotor and stator blade structural material to obtain its tensile stress-strain curves at different temperatures in order to characterize the basic mechanical properties of the rotor and stator blade structural material.

[0015] Preferably, the tensile test uses a standard round bar specimen or a thin plate specimen. The test temperature should cover the actual service temperature range of the engine rotor and stator blade structural material (including compressor rotor blade material and turbine rotor blade material, etc.), and the tensile stress-strain curve should be measured under different temperature conditions. The test strain rate should be selected to reflect the strain rate characteristics of the blade material under actual working conditions, so as to accurately characterize the mechanical response of the material in the elastic and plastic stages.

[0016] SS2. Creep test data acquisition: By conducting creep rupture tests on the engine rotor and stator blade structural material at different temperatures and stresses, its creep curves at different temperatures and stresses are obtained to characterize the creep strain characteristics of the rotor and stator blade structural material at different lifespan moments.

[0017] Preferably, the creep rupture test is carried out using standard round bar specimens or thin plate specimens. The test temperature and stress range should cover the temperature and stress range of the engine rotating and stationary blade structural components under actual working conditions. The selection of the test stress level should be able to reflect the creep behavior of the blade material at different stress levels, and the test adopts a constant temperature and constant load loading method. By setting multiple stress levels and temperature intervals, creep life data of the material under different service conditions can be obtained, and combined with short-term high-stress creep tests and long-term low-stress creep tests to improve the fitting accuracy of the creep curve, making it more in line with the life prediction requirements of short-life engine rotating and stationary blade structural components in actual engineering applications.

[0018] SS3. Extraction of creep strain data at target life: According to the target design life of the engine, extract the creep strain data at different stresses corresponding to the target design life moment from the creep curve to obtain the stress-creep strain relationship at the target design life.

[0019] Preferably, the target design life is determined according to the overall design requirements and service life requirements of the engine. When extracting the creep strain data at target life, interpolation algorithms or data fitting methods are used to expand the limited test data to ensure that the creep strain data at target life extracted at different stress levels can accurately reflect the actual creep behavior of the material, and exponential fitting, power function fitting or θ parameter method is used to fit the stress-creep strain relationship curve.

[0020] SS4. Construction of isochronous stress-strain relationship at target life: Superimpose the stress-creep strain relationship at the target design life with the tensile stress-strain curves at different temperatures to obtain the isochronous stress-strain relationship at the target design life, including the isochronous equivalent stress-equivalent total strain relationship or the isochronous equivalent stress-plastic total strain relationship.

[0021] Preferably, the isochronous stress-strain relationship can be specifically divided into the isochronous equivalent stress-equivalent total strain relationship and the isochronous equivalent stress-plastic total strain relationship according to the simulation analysis requirements.

[0022] The formula for the isochronous equivalent stress-equivalent total strain relationship is: In the formula, is the equivalent total strain of the material at the stress σ at time and are respectively the elastic strain, plastic strain and creep strain of the material at the stress σ at time

[0023] The formula for the isochronous equivalent stress - plastic total strain relationship is as follows: In the formula, is the sum of the plastic strain and creep strain of the material at the stress σ at time and are respectively the plastic strain and creep strain of the material at the stress σ at time

[0024] According to any one of the above two formulas, the isochronous stress - strain relationship of the material at different temperatures can be constructed, and then it can be directly used as the elastic - plastic constitutive model of the material and input into the finite - element model.

[0025] SS5. Finite - element analysis based on the isochronous stress - strain relationship: Input the isochronous stress - strain relationships of the material at different temperatures at the target design life time into the finite - element model of the engine rotor - stator blade structural components (including compressors and turbines), and combine with the loads and boundary conditions under the engine operating conditions to calculate and determine the stress - strain distribution of the rotor - stator blade structural components at the target design life time.

[0026] Preferably, during the finite - element analysis based on the isochronous stress - strain relationship, the finite - element model of the engine rotor - stator blade structural components adopts the real blade profile structure, and the isochronous stress - strain relationship is input as the elastic - plastic - creep constitutive model. In addition, the loads under the engine operating conditions include centrifugal force, aerodynamic load and thermal load, and the boundary conditions mainly include displacement constraints at the axial and circumferential positioning points, cyclic symmetric boundaries. For the stator structure, there are also coordinated deformation displacement constraints at the radial positioning point, and for the blade - disk with tenons, there are also contact boundaries of the tenon connections; the results of the finite - element analysis should include the stress - strain distribution of the blades at the target design life time, as well as the maximum stress and maximum strain parameters of the blades.

[0027] SS6. Optimal design of the engine rotor - stator blade structural components: Based on the finite - element calculation results, compare the calculated results of the stress - strain distribution of the life - weak parts of the rotor - stator blade structural components at the target life time with the preset failure criterion: if it is less than the failure criterion, carry out the optimization design of blade weight reduction and iterate until it approaches the failure criterion; if it is greater than the failure criterion, locally thicken or optimize the blade failure part and iterate until it does not exceed the failure criterion.

[0028] Preferably, the failure criterion is defined as that the structure fails when the equivalent total strain of the structure after creep reaches the structural failure strain. Among them, due to the influence of size effect and structural characteristics, the structural failure strain is different from the material failure strain, and the structural failure strain is obtained from the creep fracture tests of simulated blade structural components at different temperatures; the iterative optimization process takes the equivalent total strain approaching the failure criterion as the constraint condition and the minimum blade mass as the objective function. In addition, the optimization design of blade weight reduction can be to reduce the blade thickness, adjust the blade cross-sectional shape, or optimize the rotor disk or the inner and outer rings of the stator. Local thickening of the blade failure part can be to increase the material thickness or adjust the structural shape.

[0029] Through the above steps, this method can improve the creep life prediction accuracy, optimize the blade structure, improve the isochronous life matching of the compressor and turbine rotor blades, and achieve the high cost-effectiveness design of short-life engines.

[0030] Example 2: Application example Based on the above Example 1, to further verify the engineering practicability and effectiveness of the equal-life design method of the present invention based on the isochronous stress-strain relationship, in this Example 2, the compressor rotor blade and the turbine rotor blade of a certain short-life engine are taken as the specific research objects, and according to the Figure 1 shown implementation process, the equal-life design of the compressor rotor blade and the turbine rotor blade of a certain short-life engine is realized, and it includes the following steps when implemented: SS1. Through the tensile tests of the typical compressor material 2A70 and the typical turbine material K424 at different temperatures, the tensile stress-strain curves of the 2A70 material at room temperature, 100°C and 200°C, and the tensile stress-strain curves of the K424 material at 700°C, 750°C and 800°C are obtained respectively.

[0031] SS2. Through the creep fracture tests of the typical compressor material 2A70 at room temperature, 100°C and 200°C and different stresses (180 MPa to 385 MPa), and the creep fracture tests of the typical turbine material K424 at 700°C, 750°C and 800°C and different stresses (180 MPa to 385 MPa), the creep curves of the material with large stress and short life are obtained.

[0032] SS3. According to the target design life of the engine of 50 hours, the creep strains corresponding to different stresses at the moment of the target design life of 50 h are extracted from the creep curves of the 2A70 material at room temperature, 100°C and 200°C, and the creep strains corresponding to different stresses at the moment of the target design life of 50 h are extracted from the creep curves of the K424 material at 700°C, 750°C and 800°C, and the stress-creep strain relationship corresponding to the moment of the 50 h target design life is obtained.

[0033] SS4. Further superimpose the tensile stress-strain curves of 2A70 and K424 materials at their corresponding temperatures respectively, and obtain the isochronous stress-plastic strain relationships of 2A70 and K424 materials at the target design life of 50h respectively, as Figure 2 and Figure 3 shown.

[0034] SS5. Input the isochronous stress-plastic strain relationships of 2A70 and K424 materials at different temperatures at the 50h target design life into the finite element models of the compressor rotor blade and the turbine rotor blade respectively, input the loads and boundary conditions under the engine operating conditions, calculate and determine the stress and strain distributions of the compressor rotor blade and the turbine rotor blade at the 50h moment, and obtain the equivalent total strain distributions at the 50h moment respectively as Figure 4 and Figure 5 shown.

[0035] SS6. The equivalent total strain at the initial structural life weak part of the compressor rotor blade at the 50h moment is 0.00496, the corresponding temperature is 200°C, and the failure strain is 0.0401. This failure strain is obtained from the creep fracture test of the compressor rotor blade structural component simulated by 2A70 material at the same temperature; the equivalent total strain at the initial structural life weak part of the turbine rotor blade at the 50h moment is 0.00391, the corresponding temperature is 730°C, and the failure strain is 0.015. This failure strain is obtained by interpolation from the creep fracture tests of the turbine rotor blade structural components simulated by K424 materials at 700°C and 750°C.

[0036] Both are far less than the failure criterion. Further carry out the weight reduction optimization design of the blades. The comparisons of the compressor rotor blade before and after weight reduction and the turbine rotor blade before and after weight reduction are respectively as Figure 6 and Figure 7 shown. After optimization, the equivalent total strains at the life weak parts of the compressor rotor blade and the turbine rotor blade at the 50h moment are 0.0395 and 0.0144 respectively, approaching the failure criterion, thus completing the equal-life design of the compressor and turbine rotor blades. The compressor rotor blade is reduced in weight by 23%, and the turbine rotor blade is reduced in weight by 29%, significantly reducing the weight.

[0037] In summary, the equal-life design method for the stator and rotor blade structural components of the engine based on the isochronous stress-strain relationship proposed by the present invention, based on the isochronous stress-strain relationship at the target design life moment, can quickly realize the stress and strain analysis of the stator and rotor blade structural components at the target design life moment. Based on the failure criterion obtained from the simulated structural component tests of the actual blade profile, it realizes the high-reliability equal-life design of the compressor and turbine rotor blades, is very suitable for engineering design applications, has a wide range of applications, and can be used for the design of the stator and rotor blades of aeroengines and gas turbines according to the specified target life and equal-life design.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An equal-life design method for the structural components of the engine rotor and stator blades based on the isochronous stress-strain relationship, characterized in that, Including: SS1. Under different temperature conditions, perform tensile tests on the stator-rotor blade structural component materials to obtain their tensile stress-strain curves at different temperatures; SS2. Under different temperatures and stresses, perform creep rupture tests on the stator-rotor blade structural component materials to obtain their creep curves at different temperatures and stresses; SS3. According to the target design life of the engine, extract the creep strain data at different stresses corresponding to the target design life moment from the creep curve to obtain the stress-creep strain relationship at the target design life; SS4. Superimpose the stress-creep strain relationship at the target design life with the tensile stress-strain curves at different temperatures to obtain the isochronous stress-strain relationship at the target design life; SS5. Input the isochronous stress-strain relationships of the materials at different temperatures at the target design life moment into the finite element model of the stator-rotor blade structural component, and combine the loads and boundary conditions under the engine working conditions to calculate and determine the stress-strain distribution of the stator-rotor blade structural component at the target design life moment; SS6. Based on the finite element calculation results, compare the calculated results of the stress-strain distribution at the life weak parts of the stator-rotor blade structural component at the target life moment with the preset failure criterion: if it is less than the failure criterion, perform weight reduction optimization design on the blade and iterate until it approaches the failure criterion; If it is greater than the failure criterion, locally thicken or optimize the structure of the blade failure part and iterate until it does not exceed the failure criterion.

2. The isochronous life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that, In the step SS1, the tensile test uses standard round bar specimens or thin plate specimens. The test temperature covers the actual service temperature range of the stator-rotor blade structural component materials, and the selection of the test strain rate should be able to reflect the strain rate characteristics of the blade materials under the actual working conditions.

3. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that In the step SS2, the creep rupture test uses standard round bar specimens or thin plate specimens. The test temperature and stress range should cover the temperature and stress range of the engine stator-rotor blade structural component under the actual working conditions. The selection of the test stress level should be able to reflect the creep behavior of the blade materials under different stress levels. The constant temperature and constant load loading method is adopted. By setting multiple stress levels and temperature intervals, the creep life data of the materials under different service conditions are obtained, and the short-time high-stress creep test and long-time low-stress creep test are combined to improve the fitting accuracy of the creep curve.

4. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that, In the step SS3, the target design life is determined according to the overall design requirements and service life requirements of the engine. When extracting the target life creep strain data, an interpolation algorithm or a data fitting method is used to expand the limited test data, and exponential fitting, power function fitting or θ parameter method fitting is used to fit the stress-creep strain relationship curve.

5. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that, In the step SS4, according to the simulation analysis requirements, the isochronous stress-strain relationship is selected as the isochronous equivalent stress-equivalent total strain relationship, and its algorithm formula is: In the formula, is the equivalent total strain of the material at time σ and under stress and are respectively the elastic strain, plastic strain and creep strain of the material at time σ and under stress 6. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that In the step SS4, according to the simulation analysis requirements, the isochronous stress-strain relationship is selected as the isochronous equivalent stress-plastic total strain relationship, and its algorithm formula is: In the formula, is the total of the plastic strain and the creep strain of the material at the stress σ at time and are respectively the plastic strain and the creep strain of the material at the stress σ at time 7. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that, In the step SS5, the finite element model adopts the real blade profile structure, and the isochronous stress-strain relationship is input as the elastoplastic-creep constitutive model.

8. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, characterized in that, In the step SS5, the loads during the engine operation include centrifugal force, aerodynamic load and thermal load. The boundary conditions mainly include displacement constraints at the axial and circumferential positioning points, cyclic symmetric boundary. The stator structure also includes the coordinated deformation displacement constraint at the radial positioning point. The dovetail bladed disk further includes the dovetail connection contact boundary. The results of the finite element analysis should include the stress and strain distributions of the blade at the target design life time, as well as the maximum stress and maximum strain parameters of the blade.

9. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, wherein, In the step SS6, the failure criterion is defined as that the structure fails when the equivalent total strain of the structure after creep reaches the structural failure strain, where the structural failure strain is different from the material failure strain, and the structural failure strain is obtained from the creep fracture tests of the simulated blade structural components at different temperatures. The iterative optimization process is constrained by the equivalent total strain approaching the failure criterion, and the objective function is to minimize the blade mass.

10. The equal-life design method for the engine stator and rotor blade structural components based on the isochronous stress-strain relationship according to claim 1, wherein, In the step SS6, the blade weight reduction optimization includes thinning the blade thickness, adjusting the blade cross-sectional shape, or optimizing the rotor disk or the inner and outer rings of the stator. The local thickening of the blade failure part includes increasing the material thickness or adjusting the structural shape.

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