A method for predicting fatigue life of CMC structures under combined loading

Abstract

The present invention discloses a method for predicting the fatigue life of a CMC structure under composite loading, including the following steps: the first step is to carry out a sine wave fatigue test of a CMC standard plate-shaped member under different fatigue peak loads at different temperatures to obtain the performance data of the CMC under the standard sine wave fatigue load; the second step is to carry out a progressive damage analysis of the CMC structure under a given working condition to obtain the unit stress distribution; the third step is to calculate the fatigue damage of the CMC structure unit; the fourth step is to reduce the stiffness of the CMC structure to determine whether the structure fails due to fatigue. The present invention makes up for the lack of a composite fatigue life prediction method for CMC, and realizes the fatigue life prediction of CMC under complex composite loads based on the standard sine wave fatigue test.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material fatigue life prediction, and in particular relates to a CMC structure composite loading fatigue life prediction method. Background Art

[0002] Ceramic Matrix Composites (CMC) are mainly used in hot-end components of aircraft engines, including turbine rotor blades, turbine guide vanes, and tail nozzle adjustment pieces. Compared with stator components such as turbine guide vanes, rotor blades are subjected to more complex loads during actual service. They are usually affected by creep (load holding)-fatigue coupling, as well as high- and low-cycle fatigue coupling, and often face a higher risk of combined fatigue failure. At the same time, the mechanical behavior of CMC itself is relatively complex, and its failure mechanism is quite different from that of metals. Establishing a CMC fatigue life prediction method suitable for combined fatigue loading conditions is the key to promoting the development of CMC rotor blades.

[0003] At present, most CMC fatigue life prediction methods are only applicable to sinusoidal fatigue loading under specific stress ratios. By conducting a large number of sinusoidal fatigue tests, the corresponding relationship between the material hysteresis dissipation energy accumulation rate, residual stiffness, etc. and the number of cycles is established to simulate the evolution of material fatigue damage and predict fatigue life. The above methods are not applicable to special waveform service conditions under real working conditions, and fail to consider the continuous damage caused by the higher level of average stress in trapezoidal wave load and high stress ratio fatigue load, which ultimately leads to a large difference between the predicted fatigue life and the test results, and cannot meet the requirements of aircraft engine fatigue life assessment.

[0004] In summary, there is currently a lack of CMC composite fatigue life prediction methods that are more in line with the actual service load conditions of turbine rotor blades, and it is necessary to conduct research on this. Summary of the invention

[0005] The purpose of the present invention is to provide a method for predicting the fatigue life of CMC structures under complex composite fatigue loads (creep-fatigue interaction, high- and low-cycle composite loading, etc.) and failure mode assessment, and to provide a method for predicting the high-temperature composite fatigue life of CMC turbine blades that comprehensively considers the influence of the holding time and the average stress, so as to make up for the lack of composite fatigue life prediction methods. Among them, in view of the damage evolution characteristics of CMC under trapezoidal wave and high stress ratio sinusoidal wave fatigue loading, the present invention introduces equivalent damage parameters based on frequency ratio and average stress ratio, and respectively equates the CMC damage caused by trapezoidal wave and high stress ratio sinusoidal wave fatigue loading to the CMC damage under standard low stress ratio sinusoidal wave fatigue load, thereby realizing the CMC fatigue life prediction under complex composite loads based on standard sinusoidal wave fatigue test.

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

[0007] A method for predicting the fatigue life of a CMC structure under composite loading, comprising the following steps:

[0008] Step S1: performing CMC standard sine wave fatigue tests on CMC structural parts at different temperatures and different fatigue peak loads to obtain performance data of the CMC structural parts under CMC standard sine wave fatigue loads;

[0009] Step S2: establishing a macro-geometric model of the CMC structural component, the CMC structural component is composed of multiple units, and the macro-geometric model is given macro-equivalent anisotropic thermal conductivity parameters and mechanical property parameters;

[0010] Step S3: using a progressive damage algorithm to perform finite element analysis on the macro-geometry model under a given working condition, obtaining the stress distribution of the CMC structural component, and extracting the unit stress of each unit of the CMC structural component;

[0011] Step S4: Based on the unit stress extracted in step S3, fatigue load steps are applied to each unit of the CMC structural component in the macro-geometric model and fatigue damage calculation is performed;

[0012] Step S5: Based on the fatigue damage calculation result in step S4 and the performance data obtained in step 1, failure analysis is performed on the structure of each unit of the CMC structural component and stiffness reduction is performed to determine whether fatigue failure occurs in the CMC structural component after stiffness reduction. If fatigue failure occurs in the structure, the iteration is stopped and the fatigue failure simulation result of the CMC structural component is output to complete the prediction of the fatigue life of the CMC structural component. If the structure does not fail, the process returns to step S3.

[0013] To optimize the technical solution, the present invention is further improved as follows:

[0014] In step S1, the CMC standard sinusoidal wave fatigue test is specifically a plate-shaped CMC sinusoidal wave anaerobic fatigue test at multiple temperatures, with a sinusoidal fatigue load loading frequency of 10 Hz and a stress ratio of 0.1.

[0015] In step S1, the performance data of the CMC structural component under the CMC standard sine wave fatigue load is obtained by fitting the CMC standard sine wave fatigue test results to obtain the fatigue SN curve of the CMC material at different temperatures, the variation law of the hysteresis dissipated energy accumulation rate with the fatigue peak load, and the variation law of the normalized residual stiffness with the number of cycles.

[0016] In step S2, the macroscopic equivalent anisotropic thermal conductivity parameters and mechanical performance parameters specifically include thermal conductivity, material density, thermal expansion coefficient, elastic modulus, Poisson's ratio and material tensile failure strength.

[0017] In step S3, the stress distribution is the normal stress along the warp direction of the CMC structural component, and the specific working condition is: the stress distribution of the CMC structural component under the fatigue peak load.

[0018] In step S4, fatigue damage calculation is specifically as follows: using the damage equivalent method, a trapezoidal wave load with a fatigue peak load of σ or a high stress ratio sine wave load is equivalent to a fatigue peak load of The hysteresis dissipation energy accumulation rate is The standard sine wave fatigue load is is the equivalent fatigue peak load, is the equivalent hysteresis dissipated energy accumulation rate, that is, under the same loading time, the damage caused by the trapezoidal wave fatigue load to the material is the same as that of the standard sine wave load with the same fatigue peak load and the same stress ratio, that is, Where dw is the hysteresis dissipation energy accumulation rate of low stress ratio standard sine wave fatigue. At the same loading frequency, the equivalent hysteresis dissipation energy accumulation rate of high stress ratio sine wave fatigue and the hysteresis dissipation energy accumulation rate of low stress ratio standard sine wave fatigue satisfy the following relationship: is the average stress ratio, where Δσ RH is the average stress of high stress ratio sinusoidal fatigue load, Δσ RL is the average stress of the standard sine wave fatigue load with low stress ratio, By introducing the relationship between the accumulation rate of fatigue hysteresis dissipation energy and fatigue peak load of the low stress ratio standard sine wave, the equivalent fatigue peak load can be obtained. The specific process of fatigue damage calculation is as follows:

[0019] Taking the fatigue peak load σ borne by the CMC structural component unit as input, the equivalent hysteresis dissipated energy accumulation rate of the unit at the current stress level is calculated. and the equivalent fatigue peak load Then calculate the unit equivalent cycle number Where W is the equivalent cumulative hysteresis dissipation energy of the unit, and the unit experiences The residual stiffness after equivalent cyclic loading is Finally, a standard sinusoidal fatigue load with a step size of ΔN is applied to the unit. At this time, the equivalent accumulated hysteresis dissipation energy of the unit is The equivalent fatigue load step N applied to the entire CMC structure applied =ΔN+N applied , for the trapezoidal wave load, the output structure trapezoidal wave fatigue life N = N when the structure fails applied / m, where is the frequency ratio, f is the standard sinusoidal fatigue load frequency, and f tis the loading frequency of the trapezoidal wave fatigue load. For high stress ratio sine wave load, the fatigue life N=N is output when the structure fails. applied .

[0020] In step S5, the failure analysis of the unit structure includes unit fatigue failure and unit static strength failure, wherein the unit fatigue failure is: the point formed by the unit equivalent cycle number and the unit equivalent fatigue peak load Compare the relative position of the standard sine wave fatigue test SN curve obtained in step S1. If the point is located at the lower left of the SN curve, the unit will not fail. If the unit is located in the upper right of the SN curve, the unit fails due to fatigue; the static strength failure of the unit is: compare the fatigue tensile stress of the unit with the maximum tensile strength of the CMC material. If the fatigue tensile stress of the unit is less than the maximum tensile strength of the CMC material, the unit will not fail; if the fatigue tensile stress of the unit is greater than the maximum tensile strength of the CMC material, the unit will fail, and the stiffness of the failed unit will be reduced to 0.2 times the initial stiffness. If the unit does not fail, the unit stiffness will be reduced according to Make a reduction.

[0021] In step S5, the method for judging whether fatigue failure occurs in the CMC structural component is as follows: a preset failure value of the CMC structural component is set, and when the total number of failed units is greater than the preset failure value or all failed units form a failure surface that runs through the entire CMC structural component, it is considered that fatigue failure occurs in the CMC structural component.

[0022] The beneficial effect of the present invention is that the traditional CMC fatigue life prediction method usually only considers the fatigue damage caused by the friction between fiber bundles and the internal interface friction zone of the fiber bundle during the loading and unloading process of fatigue load. However, relevant experimental studies have shown that the holding time in creep-fatigue composite loading and the high average stress in high stress ratio sine wave fatigue load will also have a great impact on the fatigue life of CMC, which cannot be described by the existing CMC fatigue damage accumulation model. The present invention establishes a damage equivalence relationship based on the CMC fatigue damage mechanism, and respectively equates the CMC fatigue damage caused by trapezoidal wave fatigue load and high stress ratio fatigue load to the CMC fatigue damage caused by the corresponding low stress ratio standard sine wave fatigue load; in view of the stress redistribution phenomenon caused by the non-uniform distribution of damage in the CMC structure during fatigue loading, a composite fatigue life assessment method for the CMC structure is further proposed. Based on the life data of standard CMC plate-like parts under low stress ratio sine wave fatigue load, the present invention can realize the fatigue life prediction of complex CMC structures under creep-fatigue interaction and high and low cycle composite loading conditions, avoiding a large number of experiments, and providing an effective means for fatigue life prediction of CMC structural parts under complex service conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a method for predicting fatigue life of CMC structures under composite loading;

[0024] Figure 2 are the fatigue SN curves and fitting curves of 2.5D woven CMCs under sinusoidal loading at different temperatures in the embodiment;

[0025] Figure 3 is the relationship between the accumulation rate of hysteresis dissipation energy of the material and the fatigue peak load at different temperatures in the embodiment;

[0026] Figure 4 It is the regularized residual stiffness fitting result of 2.5D woven CMCs in the embodiment. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0028] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0029] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0030] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0031] like Figure 1 As shown, the present invention discloses a method for predicting the composite loading fatigue life of a woven ceramic matrix composite material, comprising the following steps:

[0032] Step 1: Conduct low stress ratio standard sine wave fatigue tests on 2.5D woven CMC at room temperature, 600℃, and 1100℃ in an oxygen-free environment. To obtain a complete SN curve for the material, 3-4 levels of fatigue peak loads must be selected for each temperature. In addition, the fatigue load loading frequency is 10Hz, the stress ratio is 0.1, and the upper limit of the fatigue cycle number is 10 6 Second cycle.

[0033] The test results were post-processed to obtain Figure 2 The SN curves of 2.5D woven CMC at three temperatures are shown. The SN curves at different temperatures can be fitted by the following formula, where c and a are fitting coefficients, S is the fatigue peak load, and N is the fatigue life of the specimen.

[0034] S = clg(N) + a

[0035] In addition, the material fatigue hysteresis loop (force-displacement curve) needs to be post-processed. The area enclosed by the hysteresis loop is the accumulated hysteresis dissipated energy during the fatigue loading and unloading cycle, and the ratio of the maximum test force to the maximum displacement in the hysteresis loop is the residual stiffness of the material. According to the above definition, the calculation of each cycle in the fatigue test process can be obtained as follows Figure 3 and Figure 4 The curves shown are the variation of the accumulation rate of hysteresis dissipated energy of the material with the fatigue peak load and the variation of the normalized residual stiffness of the material with the number of cycles.

[0036] The variation of the normalized residual stiffness of the material with the number of cycles can be fitted by the following formula, where E min (N) represents the residual stiffness of 2.5D woven CMC after internal damage caused by N fatigue loading and unloading, E min (0) represents the initial elastic modulus of the material, and k and b are coefficients related to the material.

[0037]

[0038] The accumulation rate of material hysteresis dissipation energy and fatigue peak load can be fitted using the following formula, where μ and α are fitting coefficients, dW is the accumulation rate of material hysteresis dissipation energy, and S is the fatigue peak load on the material.

[0039] dW=μ·S α

[0040] The second step is to establish a macro-geometric model of the CMC blade simulation. The macro-equivalent anisotropic thermal conductivity parameters and mechanical performance parameters are given to the macro-geometric model. The finite element analysis of the structural performance of the CMC blade simulation is performed using the progressive damage algorithm under given working conditions to obtain the stress distribution of the macro-geometric model along the warp direction and extract the unit stress of the CMC blade simulation.

[0041] Step 3: Based on the unit stress extracted in step 2, fatigue load steps are applied to each unit of the finite element model of the CMC blade simulation component and fatigue damage calculation is performed. For the high stress ratio sine wave fatigue life prediction, the present invention introduces the average stress ratio where Δσ RH is the average stress of high stress ratio sinusoidal fatigue load, Δσ RL is the average stress of low stress ratio sine wave fatigue load. It can be seen from the existing test results that the hysteresis dissipation energy accumulation is slow under high stress ratio sine wave load, but its higher level of average stress will also continue to damage the material. In order to comprehensively consider the contribution of both to the accumulation of material damage, the present invention defines the equivalent hysteresis dissipation energy accumulation rate of high stress ratio sine wave fatigue load as Where dw is the energy accumulation rate of fatigue hysteresis dissipation of the standard sine wave with the same peak low stress ratio. By introducing the relationship between the accumulation rate of fatigue hysteresis dissipation energy and fatigue peak load of low stress ratio sinusoidal wave, the equivalent fatigue peak load can be inferred. Through the above operation, the high stress ratio sine wave fatigue can be equivalent to the fatigue peak load of The fatigue life prediction is carried out by using the lower stress ratio of standard sine wave fatigue.

[0042] At the beginning of the first round of iterative calculation, the finite element analysis of the model shows that the fatigue tensile stress of the unit is σ 0 , from which the equivalent hysteresis dissipation energy accumulation rate under this level of fatigue load can be calculated By introducing the relationship between the fatigue hysteresis dissipation energy accumulation rate and the fatigue peak load of the standard sine wave with low stress ratio, the equivalent fatigue peak load can be obtained by reverse calculation. The equivalent accumulated hysteresis dissipated energy W of the unit before the first cyclic load is applied 0 =0, unit equivalent cycle number Computing unit experience Residual stiffness after cycles Equivalent accumulated hysteresis dissipated energy of the unit after the first application of equivalent cyclic load with a step size of ΔN Finally, count the applied load steps N applied =ΔN+N applied The equivalent cycle number of the unit is compared with the SN curve obtained by the standard sine wave fatigue test in the first step of the present invention to determine whether the unit has fatigue failure; at the same time, the fatigue tensile stress σ 0 Compare with the maximum tensile strength of the material to determine whether it has failed. If the unit fails, its stiffness is reduced to 0.2 times the initial stiffness. If the unit does not fail, its stiffness is reduced to 0.2 times the initial stiffness. Make a reduction.

[0043] Similarly, at the beginning of the nth iteration calculation, after finite element analysis of the model after stiffness degradation, it can be obtained that the fatigue tensile stress of the unit is σ n , the corresponding unit equivalent hysteresis dissipation energy accumulation rate is The equivalent fatigue peak load is Unit failure is still judged according to the unit equivalent cycle number and maximum stress criteria.

[0044] Step 4: Based on the fatigue damage calculation results in step 3, perform failure analysis on each unit of the CMC structural component and perform stiffness reduction, and count the total number of failed units. If the total number of failed units is greater than the preset upper limit or the failed units form a failure surface that runs through the entire CMC blade simulation component, the iteration ends, the fatigue damage simulation results of the CMC structural component are output, and the fatigue life prediction of the CMC structural component is completed. Otherwise, the finite element analysis is repeated and the return to step 3 is returned.

[0045] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for predicting the fatigue life of a CMC structure under composite loading, characterized in that: The following steps are involved: Step S1: performing CMC standard sine wave fatigue tests on CMC structural parts at different temperatures and different fatigue peak loads to obtain performance data of the CMC structural parts under CMC standard sine wave fatigue loads; Step S2: establishing a macro-geometric model of the CMC structural component, the CMC structural component is composed of multiple units, and the macro-geometric model is given macro-equivalent anisotropic thermal conductivity parameters and mechanical property parameters; Step S3: using a progressive damage algorithm to perform finite element analysis on the macro-geometry model under a given working condition, obtaining the stress distribution of the CMC structural component, and extracting the unit stress of each unit of the CMC structural component; Step S4: Based on the unit stress extracted in step S3, fatigue load steps are applied to each unit of the CMC structural component in the macro-geometric model and fatigue damage calculation is performed; Step S5: Based on the fatigue damage calculation result in step S4 and the performance data obtained in step 1, failure analysis is performed on the structure of each unit of the CMC structural component and stiffness reduction is performed to determine whether fatigue failure occurs to the CMC structural component after stiffness reduction. If fatigue failure occurs to the structure, the iteration is stopped and the fatigue failure simulation result of the CMC structural component is output to complete the prediction of the fatigue life of the CMC structural component. If the structure does not fail, the process returns to step S3; In step S1, the performance data of the CMC structural component under the CMC standard sine wave fatigue load is obtained by fitting the CMC standard sine wave fatigue test results to obtain the fatigue SN curve of the CMC material at different temperatures, the variation law of the hysteresis dissipated energy accumulation rate with the fatigue peak load, and the variation law of the normalized residual stiffness with the number of cycles; In step S4, fatigue damage calculation is specifically as follows: using the damage equivalent method, a trapezoidal wave load with a fatigue peak load of σ or a high stress ratio sine wave load is equivalent to a fatigue peak load of The hysteresis dissipation energy accumulation rate is The standard sine wave fatigue load is is the equivalent fatigue peak load, is the equivalent hysteresis dissipated energy accumulation rate, that is, under the same loading time, the damage caused by the trapezoidal wave fatigue load to the material is the same as that of the standard sine wave load with the same fatigue peak load and the same stress ratio, that is, Where dw is the hysteresis dissipation energy accumulation rate of low stress ratio standard sine wave fatigue. At the same loading frequency, the equivalent hysteresis dissipation energy accumulation rate of high stress ratio sine wave fatigue and the hysteresis dissipation energy accumulation rate of low stress ratio standard sine wave fatigue satisfy the following relationship: is the average stress ratio, where Δσ RH is the average stress of high stress ratio sinusoidal fatigue load, Δσ RL is the average stress of the standard sine wave fatigue load with low stress ratio, By introducing the relationship between the accumulation rate of fatigue hysteresis dissipation energy and fatigue peak load of the low stress ratio standard sine wave, the equivalent fatigue peak load can be obtained. The specific process of fatigue damage calculation is as follows: Taking the fatigue peak load σ borne by the CMC structural component unit as input, the equivalent hysteresis dissipated energy accumulation rate of the unit at the current stress level is calculated. and the equivalent fatigue peak load Then calculate the unit equivalent cycle number Where W is the equivalent cumulative hysteresis dissipation energy of the unit, and the unit experiences The residual stiffness after equivalent cyclic loading is Finally, a standard sinusoidal fatigue load with a step size of ΔN is applied to the unit. At this time, the equivalent accumulated hysteresis dissipation energy of the unit is The equivalent fatigue load step N applied to the entire CMC structure applied =ΔN+N applied , for the trapezoidal wave load, the output structure trapezoidal wave fatigue life N = N when the structure fails applied / m, where is the frequency ratio, f is the standard sinusoidal fatigue load frequency, and f t is the loading frequency of the trapezoidal wave fatigue load. For high stress ratio sine wave load, the fatigue life N=N is output when the structure fails. applied ; In step S5, the failure analysis of the unit structure includes unit fatigue failure and unit static strength failure, wherein the unit fatigue failure is: the point formed by the unit equivalent cycle number and the unit equivalent fatigue peak load Compare the relative position of the standard sine wave fatigue test SN curve obtained in step S1. If the point is located at the lower left of the SN curve, the unit will not fail. If the unit is located in the upper right of the SN curve, the unit fails due to fatigue; the static strength failure of the unit is: compare the fatigue tensile stress of the unit with the maximum tensile strength of the CMC material. If the fatigue tensile stress of the unit is less than the maximum tensile strength of the CMC material, the unit will not fail; if the fatigue tensile stress of the unit is greater than the maximum tensile strength of the CMC material, the unit will fail, and the stiffness of the failed unit will be reduced to 0.2 times the initial stiffness. If the unit does not fail, the unit stiffness will be reduced according to Make a reduction; In step S5, the method for judging whether fatigue failure occurs in the CMC structural component is as follows: a preset failure value of the CMC structural component is set, and when the total number of failed units is greater than the preset failure value or all failed units form a failure surface that runs through the entire CMC structural component, it is considered that fatigue failure occurs in the CMC structural component.

2. A CMC structure composite loading fatigue life prediction method according to claim 1, characterized in that: In step S1, the CMC standard sinusoidal wave fatigue test is specifically a plate-shaped CMC sinusoidal wave anaerobic fatigue test at multiple temperatures, with a sinusoidal fatigue load loading frequency of 10 Hz and a stress ratio of 0.

1.

3. The method for predicting the composite loading fatigue life of a CMC structure according to claim 1, characterized in that: In step S2, the macroscopic equivalent anisotropic thermal conductivity parameters and mechanical performance parameters specifically include thermal conductivity, material density, thermal expansion coefficient, elastic modulus, Poisson's ratio and material tensile failure strength.

4. The method for predicting the composite loading fatigue life of a CMC structure according to claim 1, characterized in that: In step S3, the stress distribution is the normal stress along the warp direction of the CMC structural component, and the given working condition is: the stress distribution of the CMC structural component under the fatigue peak load.

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