Method for evaluating fatigue life of engine component based on structural simulation piece
By constructing a tensile strain energy life prediction model and optimizing the design parameters of the simulated component, the problems of low accuracy and efficiency in fatigue life research of aero-engine structural components were solved, and efficient and low-cost fatigue life assessment was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIHANG UNIV
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-21
AI Technical Summary
Traditional fatigue life research methods are inaccurate and inefficient in aero-engines, have high testing costs and long testing cycles, and are difficult to apply to complex structural components.
A tensile strain energy life prediction model was constructed, the design parameters of the simulated component were optimized, the fatigue life of the structural component was evaluated through low-cycle fatigue tests on the simulated component, and the model was adjusted through a closed-loop method to improve the prediction accuracy and efficiency.
It significantly improves the accuracy and efficiency of fatigue life prediction, reduces research costs and time, is applicable to complex structural components, and overcomes the limitations of traditional methods.
Smart Images
Figure CN121902484A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of simulation data processing technology, specifically relating to a method for evaluating the fatigue life of engine components based on structural simulation parts. Background Technology
[0002] In aero-engines, the fatigue life of structural components is a crucial factor affecting engine reliability and safety. Traditional fatigue life research methods primarily rely on fatigue performance data and empirical formulas from a large number of standard material test specimens. However, the fatigue performance data from these standard specimens is insufficient to encompass key information influencing the fatigue life of real structural components (such as geometry, stress and strain gradients, stress concentration factors, and manufacturing parameters). Furthermore, aero-engine structural components are expensive, and fatigue testing is costly, resulting in a limited number of test specimens and hindering the acquisition of high-confidence reliability lifespans. Currently, this problem can be addressed by combining multi-sample simulated component reliability life testing with life testing of a small number of structural components. Simulated component fatigue life reliability testing technology includes several parts: life model, simulated component design methods, simulated component fatigue testing methods, and reliability life assessment methods. Existing research shows that this technology can effectively compensate for the limitations caused by the limited number of structural component tests, and simulated component technology has significant engineering application value.
[0003] In materials fatigue life studies, traditional strain fatigue energy methods are typically based on material hysteresis energy, i.e., assessing low-cycle damage by measuring the area of hysteresis loops on the stress-strain curve. However, when the plastic strain cycles are small, hysteresis loops are difficult to detect using engineering methods, leading to difficulties in predicting the life of stress fatigue processes. Furthermore, for materials with poor plasticity (such as certain high-temperature alloys), even in low-life, high-stress fatigue cycles, their plastic strain hysteresis loops are difficult to detect; and the pure hysteresis energy method fails to reflect the influence of mean stress and mean strain on fatigue damage. In summary, current fatigue life prediction methods suffer from low accuracy and efficiency. Moreover, the aforementioned methods rely on multi-sample simulations to ensure the accuracy of fatigue life tests, resulting in high testing costs, long testing cycles, and poor applicability to complex structures. Summary of the Invention
[0004] The purpose of this invention is to provide a fatigue life assessment method for engine components based on structural simulation parts, so as to solve the problems of low accuracy, low efficiency, high cost and long cycle of traditional methods.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows:
[0006] This invention relates to a method for fatigue life assessment of engine components based on structural simulation parts, which includes the following steps:
[0007] S1. Construct a tensile strain energy life prediction model and predict the fatigue life of structural components based on the model;
[0008] S2. Optimize the design parameters of the engine component simulation parts, manufacture the simulation parts based on the design parameters, conduct low-cycle fatigue tests on the simulation parts, and analyze the fatigue life of the simulation parts;
[0009] S3. Compare the fatigue life of the simulated component with the predicted fatigue life of the structural component. If the relative error between the two does not exceed the set error threshold, the prediction result is considered to meet the requirements, and the fatigue life of the structural component is output. Otherwise, return to S1 or S2 to re-optimize the design parameters of the simulated component or improve the tensile strain energy life prediction model.
[0010] Preferably, when constructing the tensile strain energy life prediction model in S1, the effective tensile strain energy near the maximum stress point of the structural member is defined. Tensile strain energy with single-axis symmetric cycle When the stresses are equal, they have the same fatigue life; the effective tensile strain energy near the maximum stress point of the structural member is used as the strain energy of the structural member, and the calculation formula is as follows:
[0011] (1),
[0012] in, The virtual crack length is the neighborhood of the point of maximum stress. This represents the virtual crack length. The strain energy, determined by the stress-strain cycle, is distributed along the virtual crack length.
[0013] The expression for the strain energy distributed along the virtual crack length, determined by the stress-strain cycle, is as follows:
[0014] (2),
[0015] in, For stress amplitude, For average stress, For elastic strain amplitude, For plastic strain amplitude, Stress ratio, The cyclic strain hardening index is... The cyclic strength coefficient;
[0016] The fatigue life curve of tensile strain energy with respect to a single-axis symmetric cycle is expressed as follows:
[0017] (3),
[0018] in, Indicates fatigue life. This represents the fatigue life fitting formula.
[0019] Preferably, the specific steps of S1 in predicting the fatigue life of the structural component based on the model include:
[0020] S1.1. Obtain several sets of test data. Each set of test data includes stress, elastic strain, plastic strain and life data. Divide the test data into several levels according to the magnitude of the strain amplitude, and calculate the stress amplitude, elastic strain amplitude and plastic strain amplitude of the test data in each level respectively.
[0021] S1.2. Fit the stress-strain data during the elastic deformation stage to obtain the elastic modulus;
[0022] S1.3. Fit the stress-strain average data of the plastic deformation stage to obtain the cyclic strength coefficient and cyclic strain hardening index;
[0023] S1.4. Fit the lifetime curve using all stress amplitude, strain amplitude, and lifetime data;
[0024] S1.5. Substitute the elastic modulus, cyclic strength coefficient, and cyclic strain hardening index into the formula for calculating the strain energy of the structural component to obtain the strain energy of the structural component.
[0025] S1.6. Query the fatigue life corresponding to the strain energy from the fatigue life curve.
[0026] Preferably, the fitting formula for the elastic modulus in S1.2 is:
[0027] (3),
[0028] in, For stress amplitude, For elastic strain amplitude, It is the elastic modulus.
[0029] Preferably, the fitting formulas for the cyclic strength coefficient and the cyclic strain hardening exponent in S1.3 are as follows:
[0030] (4),
[0031] (5),
[0032] in, For stress amplitude, For plastic strain amplitude, The cyclic strength coefficient, The cyclic strain hardening index is denoted as .
[0033] Preferably, the fitting formula for the S1.4 lifetime curve is:
[0034] (6),
[0035] in, For tensile strain amplitude, For elastic strain amplitude, For plastic strain amplitude, For the lifespan curve, , , , All of these are material constants.
[0036] Preferably, the specific steps for optimizing the design parameters of the simulated engine component in S2 are as follows:
[0037] S2.1. Set the parameters of the simulation component;
[0038] S2.2. Solve the stress and strain distribution of the simulated part by means of finite element analysis, extract stress and strain cloud maps, obtain the maximum stress amplitude and maximum strain amplitude, find the location and magnitude of the maximum stress and strain, extract stress and strain distribution curves in the stress concentration area, calculate the rate of change of stress and strain along a specific direction, and evaluate the magnitude of stress gradient and strain gradient.
[0039] S2.3. Based on the geometry and size of the actual engine components, a photoelastic test specimen was fabricated and subjected to the same load as the actual working conditions. The stress distribution of the actual engine components was then obtained through photoelastic testing.
[0040] S2.4. Compare the stress distribution, maximum stress, maximum strain, stress gradient, and strain gradient of the simulated part and the photoelastic test piece. If they are inconsistent, return to S2.1. If they are consistent, manufacture the simulated part based on the design parameters.
[0041] Preferably, in step S2.4, when the relative error of the stress distribution, maximum stress, maximum strain, stress gradient, and strain gradient of the simulated part and the photoelastic test part is less than 0.5%, they are determined to be consistent.
[0042] Preferably, the error threshold set in S3 is 5%.
[0043] Preferably, in step S3, when the relative error between the fatigue life of the simulated component and the predicted fatigue life of the structural component exceeds a set error threshold, the process returns to S1 or S2 to re-optimize the design parameters of the simulated component or improve the tensile strain energy life prediction model. The basis for returning to S1 or S2 is as follows: setting the number of times to return to S2 to optimize the design parameters of the simulated component in a single round and setting a threshold for the number of times the simulated component parameters are optimized. When the relative error exceeds the set error threshold, it is determined whether the number of times to return to S2 to optimize the design parameters of the simulated component in this round has reached the threshold for the number of times the simulated component parameters are optimized. If it has not reached the threshold, the process returns to S2 to optimize the design parameters of the simulated component and increments the number of times the design parameters of the simulated component are optimized by 1. If it has reached the threshold, the number of times the design parameters of the simulated component are optimized is initialized to 0 and the process returns to S1 to improve the tensile strain energy life prediction model.
[0044] Compared with the prior art, the technical solution provided by this invention has the following advantages:
[0045] 1. The present invention relates to a method for assessing the fatigue life of engine components based on structural simulation parts. This method constructs a tensile strain energy life prediction model, uses this model to predict the fatigue life of the structural components, optimizes the design parameters of the engine component simulation parts, manufactures the simulation parts based on these parameters, conducts low-cycle fatigue tests on the simulation parts, and analyzes their fatigue life. The fatigue life of the simulation parts is compared with the predicted fatigue life of the structural components to further refine the model, forming a closed-loop research method that significantly improves the accuracy and efficiency of fatigue life prediction. Simultaneously, by designing optimized structural simulation parts, the reliance on fatigue tests of multiple real structural components is reduced, significantly lowering research costs and time.
[0046] 2. The tensile strain energy life prediction model of the engine component fatigue life assessment method based on structural simulation parts of the present invention is constructed based on elastic strain energy and plastic strain energy. The determining factor of fatigue cyclic damage changes from a single hysteresis energy to elastic strain energy and plastic strain energy. The load process that determines fatigue cyclic damage changes from a complete load cycle to include not only the tensile process but also the influence of the compression process. The introduction of the tensile strain energy model overcomes the limitations of the traditional hysteresis energy method, especially the applicability problem when the plastic strain cycle is small, thereby improving the prediction accuracy. It is also applicable to complex structural parts that locally enter yielding and have a large stress-strain gradient. Attached Figure Description
[0047] Figure 1 This is a flowchart of a method for assessing the fatigue life of engine components based on structural simulation parts.
[0048] Figure 2 The figure shows a comparison between the predicted fatigue life and the test life of the simulated part in the example. Detailed Implementation
[0049] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments. The following embodiments are used to illustrate the invention, but are not intended to limit the scope of the invention.
[0050] See attached document Figure 1 As shown, the present invention relates to a method for evaluating the fatigue life of engine components based on structural simulation parts, comprising the following steps:
[0051] S1. Construct a tensile strain energy life prediction model and predict the fatigue life of structural components based on this model: Under cyclic loading, uniaxial stress specimens continuously absorb the work of external forces, leading to elastic and plastic strain cycles in the material, which in turn causes low-cycle damage accumulation. It is assumed that the low-cycle damage of the material is controlled by the combined tensile elastic strain energy and tensile plastic strain energy absorbed by the specimen under cyclic loading. Based on this assumption, the cyclic tensile strain energy is defined as the sum of the tensile elastic strain energy and the tensile plastic strain energy.
[0052] Predicting the cyclic life of structural components using material fatigue data assumes that, for the same material, when the integral of the tensile strain energy per unit area of the virtual crack in the neighborhood of the maximum stress point of the structural component is equal to the integral of the effective strain energy per unit area of the virtual engineering crack in the neighborhood of the maximum stress point of the smooth specimen during symmetrical cycling, the structural component and the smooth specimen have the same low cyclic life. Based on this assumption, the effective tensile strain energy near the maximum stress point of the structural component is defined. Tensile strain energy with single-axis symmetric cycle When the stresses are equal, they have the same fatigue life; the effective tensile strain energy near the maximum stress point of the structural member is used as the strain energy of the structural member, and the calculation formula is as follows:
[0053] (1),
[0054] in, The virtual crack length is the neighborhood of the point of maximum stress. This represents the virtual crack length. The strain energy, determined by the stress-strain cycle, is distributed along the virtual crack length.
[0055] The expression for the strain energy distributed along the virtual crack length, determined by the stress-strain cycle, is as follows:
[0056] (2),
[0057] in, For stress amplitude, For average stress, For elastic strain amplitude, For plastic strain amplitude, Stress ratio, The cyclic strain hardening index is... The cyclic strength coefficient;
[0058] The fatigue life curve of tensile strain energy with respect to a single-axis symmetric cycle is expressed as follows:
[0059] (3),
[0060] in, Indicates fatigue life. The fatigue life fitting formula represents the effective tensile strain energy near the maximum stress point of a structural component. ,available The corresponding fatigue life.
[0061] The specific steps for predicting the fatigue life of structural components based on this model include:
[0062] S1.1. Obtain several sets of experimental data, taken from sources such as the "1Cr11Ni2W2MoV, 200℃ Low Cycle Fatigue Test Report" from a certain aerospace materials research institute. Each set of experimental data includes stress, elastic strain, plastic strain, and life data, arranged according to the strain amplitude Δε. t The size of / 2 divides the test data into several levels, and the stress amplitude, elastic strain amplitude and plastic strain amplitude of the test data in each level are calculated respectively;
[0063] S1.2. During the elastic deformation stage, stress and strain have a linear relationship. Therefore, the elastic modulus can be obtained by linearly fitting the stress-strain data during the elastic deformation stage. The fitting formula for the elastic modulus is:
[0064] (3),
[0065] in, For stress amplitude, For elastic strain amplitude, It is the elastic modulus;
[0066] S1.3. Fit the stress-strain average data during the plastic deformation stage to obtain the cyclic strength coefficient and cyclic strain hardening index. During the plastic deformation stage, the relationship between stress and strain usually follows the following power law relationship, as shown in the following equation:
[0067] (4),
[0068] Taking the logarithm of the stress-strain data during the plastic deformation stage can transform it into a linear relationship, as shown in the following formula:
[0069] (5),
[0070] Therefore, the cyclic strength coefficient and the cyclic strain hardening exponent can be fitted using equations (4) and (5). In the above equations, For stress amplitude, For plastic strain amplitude, The cyclic strength coefficient, The cyclic strain hardening index;
[0071] S1.4. Fit the life curve using all stress amplitude, strain amplitude, and life data. The fitting formula is:
[0072] (6),
[0073] in, For tensile strain amplitude, For elastic strain amplitude, For plastic strain amplitude, For the lifespan curve, , , , All are material constants;
[0074] This model is based on elastic strain energy and plastic strain energy. The determinant of fatigue cyclic damage changes from a single hysteresis energy to elastic strain energy and plastic strain energy. The load process that determines fatigue cyclic damage changes from a complete load cycle to include not only the tensile process but also the influence of the compression process. The introduction of the tensile strain energy model overcomes the limitations of the traditional hysteresis energy method.
[0075] S1.5. Substitute the elastic modulus, cyclic strength coefficient, and cyclic strain hardening index into the formula for calculating the strain energy of the structural component to obtain the strain energy of the structural component.
[0076] S1.6. Query the fatigue life corresponding to the strain energy from the fatigue life curve.
[0077] S2. Optimize the design parameters of the engine component simulation parts, manufacture the simulation parts based on the design parameters, conduct low-cycle fatigue tests on the simulation parts, and analyze the fatigue life of the simulation parts. The specific steps are as follows:
[0078] S2.1. Set the parameters of the simulation component;
[0079] S2.2. The stress and strain distribution of the simulated component is solved using the finite element method. External software is used to extract stress and strain contour maps, obtain the maximum stress amplitude and maximum strain amplitude, locate the position and magnitude of the maximum stress and strain, extract stress and strain distribution curves in the stress concentration region, calculate the rate of change of stress and strain along a specific direction, and then evaluate the magnitude of the stress gradient and strain gradient. The rate of change of stress along a specific direction is the stress gradient, and the rate of change of strain along a specific direction is the strain gradient. Stress gradient = Strain gradient = The finite element analysis method is based on software such as ANSYS finite element analysis. Stress and strain contour plots can be extracted using Abaqus and ANSYS software, both of which are existing technologies and are not covered by the present invention. This embodiment will not elaborate on them in detail.
[0080] S2.3. Based on the geometry and dimensions of real engine components, fabricate photoelastic test specimens and apply loads identical to those under actual operating conditions. Then, simulate the stress distribution of the real engine components through photoelastic testing. Photoelastic testing can be conducted using a GB pulse test bench, which is also existing technology. Specific steps include:
[0081] (1) Prepare photoelastic test specimens to ensure that their geometry and dimensions are consistent with the actual structural parts;
[0082] (2) Apply the same load as the actual working condition to the test specimen;
[0083] (3) Use a photoelastic instrument to observe and record the stress distribution;
[0084] S2.4. Compare the stress distribution, maximum stress, maximum strain, stress gradient, and strain gradient of the simulated part and the photoelastic test piece. If they are inconsistent, return to S2.1. If they are consistent, manufacture the simulated part based on the design parameters. In this embodiment, when the relative error of the stress distribution, maximum stress, maximum strain, stress gradient, and strain gradient of the simulated part and the photoelastic test piece is less than 0.5%, it is determined to be consistent.
[0085] S3. This embodiment takes the design and low-cycle fatigue testing of a dovetail tenon groove low-cycle fatigue simulation component for a compressor stage 1 disk as an example. S1 is used to obtain the calculated fatigue life, and S2 is used to obtain the experimental fatigue life, as shown below. Figure 2As shown. The fatigue life of the simulated component is compared with the predicted fatigue life of the structural component. If the relative error between the two does not exceed the set error threshold (5%), the prediction result is considered to meet the requirements, and the fatigue life of the structural component is output. Otherwise, return to S1 or S2 to re-optimize the design parameters of the simulated component or improve the tensile strain energy life prediction model. The basis for returning to S1 or S2 is: set the number of times n is returned to S2 to optimize the design parameters of the simulated component in a single round and the threshold N for the number of times the simulated component parameters are optimized. The initial value of n is 0, and N > 0. When the relative error exceeds the set error threshold, it is determined whether the number of times n is returned to S2 to optimize the design parameters of the simulated component in this round reaches the threshold N for the number of times the simulated component parameters are optimized. If it does not reach the threshold N, return to S2 to optimize the design parameters of the simulated component and increment the number of times the design parameters of the simulated component are optimized by 1. If it reaches the threshold N, initialize the number of times the design parameters of the simulated component are optimized to 0 and return to S1 to improve the tensile strain energy life prediction model.
[0086] The present invention has been described in detail above with reference to the embodiments, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.
Claims
1. A method for evaluating the fatigue life of engine components based on structural simulation parts, characterized in that: It includes the following steps: S1. Construct a tensile strain energy life prediction model and predict the fatigue life of structural components based on the model; S2. Optimize the design parameters of the engine component simulation parts, manufacture the simulation parts based on the design parameters, conduct low-cycle fatigue tests on the simulation parts, and analyze the fatigue life of the simulation parts; S3. Compare the fatigue life of the simulated component with the predicted fatigue life of the structural component. If the relative error between the two does not exceed the set error threshold, the prediction result is considered to meet the requirements, and the fatigue life of the structural component is output. Otherwise, return to S1 or S2 to re-optimize the design parameters of the simulated component or improve the tensile strain energy life prediction model.
2. The method for evaluating the fatigue life of engine components based on structural simulation parts according to claim 1, characterized in that: When constructing the tensile strain energy life prediction model in S1, the effective tensile strain energy near the maximum stress point of the structural member is defined. Tensile strain energy with single-axis symmetric cycle When the stresses are equal, they have the same fatigue life; the effective tensile strain energy near the maximum stress point of the structural member is used as the strain energy of the structural member, and the calculation formula is as follows: （1）， in, The virtual crack length is the neighborhood of the point of maximum stress. This represents the virtual crack length. The strain energy, determined by the stress-strain cycle, is distributed along the virtual crack length. The expression for the strain energy distributed along the virtual crack length, determined by the stress-strain cycle, is as follows: （2）， in, For stress amplitude, For average stress, For elastic strain amplitude, For plastic strain amplitude, Stress ratio, The cyclic strain hardening index is... The cyclic strength coefficient; The fatigue life curve of tensile strain energy with respect to a single-axis symmetric cycle is expressed as follows: （3）， in, Indicates fatigue life. This represents the fatigue life fitting formula.
3. The fatigue life assessment method for engine components based on structural simulation parts according to claim 2, characterized in that: The specific steps of S1 in predicting the fatigue life of structural components based on this model include: S1.
1. Obtain several sets of test data. Each set of test data includes stress, elastic strain, plastic strain and life data. Divide the test data into several levels according to the magnitude of the strain amplitude, and calculate the stress amplitude, elastic strain amplitude and plastic strain amplitude of the test data in each level respectively. S1.
2. Fit the stress-strain data during the elastic deformation stage to obtain the elastic modulus; S1.
3. Fit the stress-strain average data of the plastic deformation stage to obtain the cyclic strength coefficient and cyclic strain hardening index; S1.
4. Fit the lifetime curve using all stress amplitude, strain amplitude, and lifetime data; S1.
5. Substitute the elastic modulus, cyclic strength coefficient, and cyclic strain hardening index into the formula for calculating the strain energy of the structural component to obtain the strain energy of the structural component. S1.
6. Query the fatigue life corresponding to the strain energy from the fatigue life curve.
4. The fatigue life assessment method for engine components based on structural simulation parts according to claim 3, characterized in that: The fitting formula for the elastic modulus in S1.2 is as follows: （3）， in, For stress amplitude, For elastic strain amplitude, It is the elastic modulus.
5. The fatigue life assessment method for engine components based on structural simulation parts according to claim 3, characterized in that: The fitting formulas for the cyclic strength coefficient and cyclic strain hardening exponent in S1.3 are as follows: （4）， （5）， in, For stress amplitude, For plastic strain amplitude, The cyclic strength coefficient, The cyclic strain hardening index is denoted as .
6. The fatigue life assessment method for engine components based on structural simulation parts according to claim 3, characterized in that: The fitting formula for the S1.4 lifetime curve is: （6）， in, For tensile strain amplitude, For elastic strain amplitude, For plastic strain amplitude, For the lifespan curve, , , , All of these are material constants.
7. The fatigue life assessment method for engine components based on structural simulation parts according to claim 1, characterized in that: The specific steps for optimizing the design parameters of the simulated engine components in S2 are as follows: S2.
1. Set the parameters of the simulation component; S2.
2. Solve the stress and strain distribution of the simulated part by means of finite element analysis, extract stress and strain cloud maps, obtain the maximum stress amplitude and maximum strain amplitude, find the location and magnitude of the maximum stress and strain, extract stress and strain distribution curves in the stress concentration area, calculate the rate of change of stress and strain along a specific direction, and evaluate the magnitude of stress gradient and strain gradient. S2.
3. Based on the geometry and size of the actual engine components, a photoelastic test specimen was fabricated and subjected to the same load as the actual working conditions. The stress distribution of the actual engine components was then obtained through photoelastic testing. S2.
4. Compare the stress distribution, maximum stress, maximum strain, stress gradient, and strain gradient of the simulated part and the photoelastic test piece. If they are inconsistent, return to S2.
1. If they are consistent, manufacture the simulated part based on the design parameters.
8. The fatigue life assessment method for engine components based on structural simulation parts according to claim 7, characterized in that: In S2.4, when the relative error of the stress distribution, maximum stress, maximum strain, stress gradient, and strain gradient of the simulated part and the photoelastic test part is less than 0.5%, they are judged to be consistent.
9. The method for evaluating the fatigue life of engine components based on structural simulation parts according to claim 1, characterized in that: The error threshold set in S3 is 5%.
10. The method for evaluating the fatigue life of engine components based on structural simulation parts according to claim 1, characterized in that: When the relative error between the fatigue life of the simulated component and the predicted fatigue life of the structural component exceeds a set error threshold in step S3, the system returns to S1 or S2 to re-optimize the design parameters of the simulated component or improve the tensile strain energy life prediction model. The basis for returning to S1 or S2 is: setting the number of times to return to S2 to optimize the design parameters of the simulated component in a single round and setting a threshold for the number of times the simulated component parameters are optimized. When the relative error exceeds the set error threshold, it is determined whether the number of times to return to S2 to optimize the design parameters of the simulated component in this round has reached the threshold for the number of times the simulated component parameters are optimized. If it has not reached the threshold, the system returns to S2 to optimize the design parameters of the simulated component and increments the number of times the design parameters of the simulated component are optimized by 1. If it has reached the threshold, the number of times the design parameters of the simulated component are optimized is initialized to 0 and the system returns to S1 to improve the tensile strain energy life prediction model.