Alloy component low-cycle fatigue life prediction method, device, equipment and medium

Abstract

The application discloses an alloy component low-cycle fatigue life prediction method, device, equipment and medium, relates to the high-temperature alloy fatigue life prediction technical field, and includes: aiming at the alloy component successively bearing the thermal mechanical fatigue first stage load and the isothermal low-cycle fatigue second stage load, taking the ratio of the first stage preloading cycle number and the corresponding reference life as the component first stage pre-damage, combining the second stage control stress, the fatigue damage threshold stress and the tensile strength selected according to the component sample type to solve the second stage damage index, converting the first stage pre-damage into the equivalent consumed cycle number corresponding to the second stage load based on the second stage nonlinear damage evolution relationship, subtracting the equivalent consumed cycle number from the second stage reference life to obtain the low-cycle fatigue residual life of the component after the thermal mechanical fatigue pre-damage. The residual low-cycle fatigue life of the alloy component under the action of two-stage sequential load is accurately calculated, and the prediction error generated by the traditional linear damage conversion mode is avoided.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy fatigue life prediction technology, and particularly to methods, devices, equipment and media for predicting low-cycle fatigue life of alloy components. Background Technology

[0002] Aero-engine turbine blades, guide vanes, and other hot-end components typically endure complex temperature and mechanical cyclic loads during service. During startup, shutdown, and variable operating conditions, these components experience TMF (Thermo-Mechanical Fatigue); in the subsequent high-temperature stable operation phase, they may continue to experience ITLCF (Isothermal Low Cycle Fatigue) loads. Therefore, a sequential fatigue loading path—first thermo-mechanical fatigue, then low-cycle fatigue—is of engineering significance.

[0003] Traditional Miner's linear damage criterion typically assumes that damage is proportional to lifetime fraction and further believes that lifetime fractions at different loading stages can be directly linearly added. However, nickel-based single-crystal superalloys exhibit nonlinear damage evolution behaviors during high-temperature fatigue, including microcrack initiation and propagation, oxidation damage, void growth, γ' phase degradation, and a reduction in local effective load-bearing area, with damage accelerating significantly in the later stages of the fatigue life. Therefore, simply adding lifetime fractions cannot accurately describe the impact of thermomechanical fatigue pre-damage on the remaining lifetime of subsequent low-cycle fatigue. In DD6 single-crystal alloy under TMF→ITLCF sequential loading, the remaining lifetime of the second-stage ITLCF decreases significantly nonlinearly with the increase of the lifetime fraction of the first-stage TMF pre-loading, indicating that the first-stage TMF pre-damage not only consumes lifetime but also alters the damage evolution state of the second stage.

[0004] In summary, how to accurately calculate the remaining low-cycle fatigue life of alloy components subjected to sequential loads of thermomechanical fatigue and isothermal low-cycle fatigue, and eliminate the prediction error caused by linear damage conversion, is a problem that needs to be solved in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method, apparatus, equipment, and medium for predicting the low-cycle fatigue life of alloy components, accurately calculating the remaining low-cycle fatigue life of alloy components subjected to sequential loads of thermomechanical fatigue and isothermal low-cycle fatigue, and eliminating prediction errors caused by linear damage conversion. The specific solution is as follows: In a first aspect, this application discloses a method for predicting the low-cycle fatigue life of alloy components, including: The ratio between the number of preload cycles of the component to be evaluated in the first stage and the baseline lifetime in the first stage is determined as the pre-damage of the component to be evaluated in the first stage. The control stress for the second stage is determined based on the specimen type of the component to be evaluated; The damage index of the component under evaluation in the second stage is determined based on the control stress and the fatigue damage threshold stress and tensile strength of the component under evaluation in the second stage. Based on the nonlinear damage evolution relationship of the second stage, the pre-damage of the first stage is equivalently converted into the equivalent number of cycles consumed under the second stage. The low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage is predicted based on the difference between the baseline life of the component under evaluation in the second stage and the equivalent number of cycles consumed. The component to be evaluated is an alloy component that has undergone a first stage load and a second stage load in sequence. The first stage is a thermomechanical fatigue preloading stage, and the second stage is an isothermal low-cycle fatigue loading stage.

[0006] Optionally, determining the control stress for the second stage based on the specimen type of the component to be evaluated includes: If the specimen type of the component to be evaluated is a round bar specimen, then the nominal maximum stress of the component to be evaluated in the second stage is determined as the control stress of the second stage. If the specimen type of the component to be evaluated is a flat plate specimen with a circular hole, the local equivalent stress at the hole edge of the component to be evaluated is obtained by the continuous integration method or the finite element discretization method, and the local equivalent stress at the hole edge of the component to be evaluated is determined as the control stress of the second stage.

[0007] Optionally, the local equivalent stress at the hole edge of the component to be evaluated is obtained using a continuous integration method, including: The effective damage zone of the hole edge is delineated outward from the critical point where the stress at the edge of the circular hole of the component to be evaluated is the point where the stress is the greatest. In the peak tensile state of the second stage, the maximum principal stress is extracted from the critical point of the edge of the circular hole of the component to be evaluated in the direction away from the edge of the hole. A stress weighting index is introduced to apply a power weight to the maximum principal stress, and the weighted stress is integrated within the effective damage zone of the hole edge. The integrated result is then processed using the length of the effective damage zone of the hole edge and the stress weighting index to obtain the local equivalent stress at the hole edge of the component to be evaluated.

[0008] Optionally, the local equivalent stress at the hole edge of the component to be evaluated is obtained using the finite element discretization method, including: The effective damage zone of the hole edge is delineated outward from the critical point where the stress at the edge of the circular hole of the component to be evaluated is the critical point where the stress at the edge of the circular hole is the greatest. In the peak tensile state of the second stage, the distances of all finite element discrete nodes from the edge of the hole and the maximum principal stress of the corresponding nodes are extracted from the critical point of the edge of the circular hole of the component to be evaluated in the direction away from the edge of the hole. A stress weighting index is introduced to perform power-law weighting on the maximum principal stress of adjacent discrete nodes. The weighted stress within the adjacent node interval is summed piecewise using a trapezoidal integral method. The summed result is then processed using the length of the effective damage zone at the hole edge and the stress weighting index to obtain the local equivalent stress at the hole edge of the component to be evaluated.

[0009] Optionally, determining the damage index of the component under evaluation in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component under evaluation in the second stage includes: The average stress of the component under evaluation in the second stage is obtained based on the control stress and the low-cycle fatigue stress ratio of the component under evaluation in the second stage. The fatigue damage threshold stress of the component to be evaluated in the second stage is corrected by using the average stress of the second stage to obtain the corrected threshold stress. The damage index of the component to be evaluated in the second stage is determined based on the control stress, the corrected threshold stress, and the tensile strength of the component to be evaluated in the second stage.

[0010] Optionally, the formula for obtaining the corrected threshold stress is: ; In the formula, To correct the threshold stress, This represents the fatigue limit corresponding to the second stage of fully reverse loading conditions. This is the average stress correction factor. The average stress in the second stage; Accordingly, the formula for obtaining the damage index in the second stage is: ; In the formula, This is the damage index for the second stage. For material parameters, For the control stress of the second stage, For the second phase Corrected threshold stress at temperature For the second phase Tensile strength at temperature.

[0011] Optionally, the formula for obtaining the equivalent number of cycles consumed is: ; In the formula, The pre-damage of the component to be evaluated in the first stage. This is the damage index for the second stage. For the equivalent number of loops consumed, The reference life of the component to be evaluated in the second stage is the low-cycle fatigue reference life of the component to be evaluated under the same second-stage load without experiencing the first-stage load damage.

[0012] Secondly, this application discloses a device for predicting the low-cycle fatigue life of alloy components, comprising: A pre-damage determination module is used to determine the ratio between the number of preload cycles of the component to be evaluated in the first stage and the reference life of the first stage as the pre-damage of the component to be evaluated in the first stage. The stress determination module is used to determine the control stress for the second stage based on the specimen type of the component to be evaluated; The damage index determination module is used to determine the damage index of the component to be evaluated in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component to be evaluated in the second stage. The equivalent conversion module is used to convert the pre-damage of the first stage into the equivalent number of consumed cycles in the second stage based on the nonlinear damage evolution relationship of the second stage. The life prediction module is used to predict the low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage based on the difference between the baseline life of the component under evaluation in the second stage and the equivalent number of cycles consumed. The component to be evaluated is an alloy component that has undergone a first stage load and a second stage load in sequence. The first stage is a thermomechanical fatigue preloading stage, and the second stage is an isothermal low-cycle fatigue loading stage.

[0013] Thirdly, this application discloses an electronic device, including: Memory is used to store computer programs; A processor is used to execute the computer program to implement the steps of the aforementioned disclosed method for predicting the low-cycle fatigue life of alloy components.

[0014] Fourthly, this application discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the steps of the aforementioned disclosed method for predicting the low-cycle fatigue life of alloy components.

[0015] The beneficial effects of this application are as follows: This application determines the pre-damage of the component under evaluation in the first stage as the ratio between the pre-loading cycle number and the reference life in the first stage; determines the control stress in the second stage according to the sample type of the component under evaluation; determines the damage index of the component under evaluation in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component under evaluation in the second stage; converts the pre-damage in the first stage into the equivalent consumed cycle number in the second stage based on the nonlinear damage evolution relationship in the second stage; predicts the low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage based on the difference between the reference life and the equivalent consumed cycle number in the second stage; wherein, the component under evaluation is an alloy component that has successively experienced the first stage load and the second stage load, the first stage is the thermomechanical fatigue pre-loading stage, and the second stage is the isothermal low-cycle fatigue loading stage. Therefore, this application directly characterizes the first-stage thermomechanical fatigue pre-damage by using the ratio of the first-stage pre-loading cycle number to the corresponding baseline thermomechanical fatigue life. This eliminates the need to accumulate multiple damage components cycle by cycle, simplifying the calculation process for the first-stage damage. The second-stage control stress is selected based on the sample type, matching the actual damage control area of ​​components with different geometries and reducing prediction bias caused by using only a uniform nominal stress. Furthermore, by combining the second-stage control stress, fatigue damage threshold stress, and tensile strength to calculate the damage index, the damage index can dynamically change with the actual stress state of the component, accurately reflecting the damage of nickel-based single-crystal superalloys at high temperatures. The nonlinear development law, based on the nonlinear damage evolution relationship of the second stage, completes the conversion of the first stage pre-damage to the equivalent consumed cycle number under the second stage load, replacing the traditional Miner linear damage criterion's calculation method of directly deducting the life fraction. It can restore the nonlinear loss effect of thermomechanical fatigue pre-damage on the subsequent isothermal low-cycle fatigue life. Finally, the remaining life is obtained by subtracting the equivalent consumed cycle number from the second stage reference life. The calculation logic fits the actual service load sequence of the component first undergoing thermomechanical fatigue and then isothermal low-cycle fatigue, improving the consistency between the low-cycle fatigue remaining life prediction results of components with thermomechanical pre-damage and the experimental measured data. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a flowchart of a method for predicting the low-cycle fatigue life of alloy components disclosed in this application. Figure 2 This is a schematic diagram of fatigue loading waveforms at different stages as disclosed in this application; Figure 3 This is a flowchart of a specific method for predicting the low-cycle fatigue life of alloy components disclosed in this application. Figure 4 This is a schematic diagram illustrating the path distribution of the maximum principal stress at the edge of a hole and the calculation of the local equivalent stress at the edge of the hole, as disclosed in this application. Figure 5 This is a schematic diagram of the low-cycle fatigue life prediction device for alloy components disclosed in this application. Figure 6 This is a structural diagram of an electronic device disclosed in this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Aero-engine turbine blades, guide vanes, and other hot-end components typically endure complex temperature and mechanical cyclic loads during service. During startup, shutdown, and variable operating conditions, these components experience TMF (Thermo-Mechanical Fatigue); in the subsequent high-temperature stable operation phase, they may continue to experience ITLCF (Isothermal Low Cycle Fatigue) loads. Therefore, a sequential fatigue loading path—first thermo-mechanical fatigue, then low-cycle fatigue—is of engineering significance.

[0020] Traditional Miner's linear damage criterion typically assumes that damage is proportional to lifetime fraction and further believes that lifetime fractions at different loading stages can be directly linearly added. However, nickel-based single-crystal superalloys exhibit nonlinear damage evolution behaviors during high-temperature fatigue, including microcrack initiation and propagation, oxidation damage, void growth, γ' phase degradation, and a reduction in local effective load-bearing area, with damage accelerating significantly in the later stages of the fatigue life. Therefore, simply adding lifetime fractions cannot accurately describe the impact of thermomechanical fatigue pre-damage on the remaining lifetime of subsequent low-cycle fatigue. In DD6 single-crystal alloy under TMF→ITLCF sequential loading, the remaining lifetime of the second-stage ITLCF decreases significantly nonlinearly with the increase of the lifetime fraction of the first-stage TMF pre-loading, indicating that the first-stage TMF pre-damage not only consumes lifetime but also alters the damage evolution state of the second stage.

[0021] Therefore, this application provides a corresponding low-cycle fatigue life prediction scheme for alloy components, which accurately calculates the remaining low-cycle fatigue life of alloy components subjected to two sequential loads of thermomechanical fatigue and isothermal low-cycle fatigue, eliminating the prediction error caused by linear damage conversion.

[0022] See Figure 1 As shown in the embodiments of this application, a method for predicting the low-cycle fatigue life of alloy components is disclosed, including: Step S11: The ratio between the number of preload cycles of the component to be evaluated in the first stage and the baseline life of the first stage is determined as the pre-damage of the component to be evaluated in the first stage.

[0023] like Figure 2 As shown, the component under evaluation is subjected to thermomechanical fatigue. In the subsequent high-temperature stable operation stage, the component may continue to be subjected to isothermal low-cycle fatigue loads.

[0024] It is understandable that, such as Figure 2 As shown in (a), during the thermomechanical fatigue preloading stage, the alloy component to be evaluated will be subjected to thermally coupled cyclic loads, such as... Figure 2 As shown in (b), after the thermomechanical fatigue preloading stage, the component may continue to be subjected to isothermal low-cycle fatigue loads. After the thermomechanical fatigue preloading stage, the component has reached a certain damage state, forming thermomechanical fatigue pre-damage D in this stage. Taking the first stage as the thermomechanical fatigue preloading stage, it is denoted as... ,in, The formula for obtaining the pre-damage in the first stage is: ; In the formula, This is the number of preloading loops in the first phase. This is the baseline lifespan for the first stage.

[0025] It is important to note the pre-damage in the first stage. Instead of accumulating fatigue damage components, creep damage components, or fatigue-creep interaction damage components cycle by cycle during the thermomechanical fatigue stage, the number of pre-loading cycles in the first stage of thermomechanical fatigue is collected. Reference thermomechanical fatigue life under the same thermomechanical fatigue loading conditions Dividing the number of preloading cycles by the baseline thermomechanical fatigue life yields a dimensionless ratio, which represents the thermomechanical fatigue pre-damage formed on the component during this stage. This value intuitively quantifies the initial damage caused by thermomechanical fatigue load to the interior of the component. The value ranges from 0 to 1. The closer the value is to 1, the more internal micro-damage the component accumulates in the first stage.

[0026] It should be noted that when this ratio is equal to or greater than 1, that is... ≥ This indicates that the component has already experienced fatigue failure under the first stage of loading, and there is no need to perform subsequent remaining life calculations, i.e., the remaining life of the second stage isothermal low-cycle fatigue. .

[0027] This damage quantification method relies on the correspondence between basic cycles and lifespan to complete damage quantification. The calculation logic is simple and clear, and it can stably characterize the initial damage state of components under different cycle numbers, providing a unified damage state quantification benchmark for subsequent damage equivalence conversion between different types of fatigue loads.

[0028] Step S12: Determine the control stress for the second stage based on the specimen type of the component to be evaluated.

[0029] In this embodiment, determining the control stress of the second stage based on the specimen type of the component to be evaluated includes: if the specimen type of the component to be evaluated is a round bar specimen, then the nominal maximum stress of the component to be evaluated in the second stage is determined as the control stress of the second stage; if the specimen type of the component to be evaluated is a round hole plate specimen, then the local equivalent stress at the hole edge of the component to be evaluated is obtained by using the continuous integration method or the finite element discretization method, and the local equivalent stress at the hole edge of the component to be evaluated is determined as the control stress of the second stage.

[0030] like Figure 3 As shown, the second stage is the isothermal low-cycle fatigue loading stage, where the component is only subjected to isothermal mechanical cyclic loads. Because the damage control areas of the round bar specimen and the round hole plate specimen are different, the control stress for damage calculation needs to be selected according to the differences in the geometric type of the component specimen. .

[0031] If the component to be evaluated is a round bar specimen without stress concentration, its overall stress distribution is uniform and there are no local high stress gradient regions, the nominal maximum stress of the component under the second stage loading condition can be directly used. The second-stage control stress can accurately characterize the overall fatigue damage driving load, i.e. The component to be evaluated is a nickel-based single-crystal superalloy component, specifically a DD6 nickel-based single-crystal superalloy round bar sample, a round hole plate sample, or a hot-end component of an aero-engine containing film cooling holes.

[0032] If the component to be evaluated is a flat plate specimen with a circular hole, a significant stress concentration and gradient stress field distributed along the damage path will form at the edge of the hole. Using only the nominal maximum stress will underestimate the local damage development rate. Therefore, two switchable calculation methods are provided to solve the local equivalent stress at the hole edge suitable for this type of component: the continuous integration method adapted to theoretical function input and the finite element discrete trapezoidal integration method adapted to finite element discrete node data. Both methods delineate a fixed-length effective damage zone outward from the critical point of maximum stress at the edge of the circular hole and extract the maximum principal stress on the path to complete the weighted calculation. Finally, the obtained local equivalent stress at the hole edge is calculated. The control stress in the second stage of the circular hole plate specimen ,Right now .

[0033] By matching the selection rules of control stress by type, it is possible to adapt to the real stress distribution characteristics of smooth specimens and stress concentration components with holes, and eliminate the damage and life prediction deviation caused by uniformly using nominal stress calculation.

[0034] In a specific embodiment of obtaining the local equivalent stress at the hole edge in the first type, the continuous integration method is used to obtain the local equivalent stress at the hole edge of the component to be evaluated. This includes: delineating an effective damage zone at the hole edge outward from the critical point where the stress at the edge of the circular hole of the component to be evaluated is the maximum; extracting the maximum principal stress from the critical point at the edge of the circular hole of the component to be evaluated along the direction away from the hole edge under the peak tensile state in the second stage; introducing a stress weighting index to perform power weighting on the maximum principal stress; and performing an integral operation on the weighted stress within the interval of the effective damage zone at the hole edge; and processing the obtained integral result using the length of the effective damage zone at the hole edge and the stress weighting index to obtain the local equivalent stress at the hole edge of the component to be evaluated.

[0035] When using the continuous integration method to solve the local equivalent stress at the edge of a circular hole plate specimen, the critical point with the highest stress concentration at the hole edge under the second-stage peak tensile condition is first located. Starting from this critical point, a fixed-length effective damage zone is delineated away from the hole wall. This zone is the core area for the initiation and propagation of fatigue micro-damage at the hole edge. Then, the maximum principal stress function, which continuously varies with distance from the hole edge along this extension path, is extracted. A preset stress weighting index is introduced to perform power-law weighting on the maximum principal stress at each point along the path, thereby amplifying the dominant role of the high-stress region in the overall fatigue damage. The stress function after power-law weighting is then integrally calculated over the distance interval corresponding to the entire effective damage zone at the hole edge, obtaining the total integral of the weighted stress within the effective damage zone. This total integral is divided by the length of the effective damage zone at the hole edge to perform stress averaging. Finally, the stress weighting index corresponding to the averaged overall value is square-rooted. The specific formula is as follows: ; In the formula, To extract the maximum principal stress from the critical point at the edge of the circular hole of the component under evaluation in the peak tensile state during the second stage, along the direction away from the hole edge, where r=0 represents the point of maximum principal stress at the edge of the circular hole. denoted as , where m is the length of the effective damage zone around the hole, and m is the weighting index.

[0036] The value obtained after complete calculation is the local equivalent stress at the hole edge that can be used for subsequent damage index calculation. This continuous integration method relies on a complete and continuous stress function to carry out theoretical solutions, which can completely restore the comprehensive effect of the gradient stress field in the damage zone on fatigue damage, and provide accurate theoretical control stress input for circular hole components.

[0037] In a specific embodiment of the second method for obtaining the local equivalent stress at the hole edge, the finite element discretization method is used to obtain the local equivalent stress at the hole edge of the component to be evaluated. This includes: delineating an effective damage zone at the hole edge outward from the critical point where the stress at the edge of the circular hole of the component to be evaluated is the maximum; extracting the distance from the hole edge to all finite element discrete nodes and the maximum principal stress of the corresponding nodes along the stress path from the critical point at the edge of the circular hole of the component to be evaluated in the direction away from the hole edge during the second stage of peak tensile state; introducing a stress weighting index to perform power-law weighting on the maximum principal stress of adjacent discrete nodes respectively; using a trapezoidal integral method to complete the piecewise summation of the weighted stress within the interval of adjacent nodes; and processing the obtained summation result using the length of the effective damage zone at the hole edge and the stress weighting index to obtain the local equivalent stress at the hole edge of the component to be evaluated.

[0038] When using the finite element discrete trapezoidal integration method to solve the local equivalent stress at the edge of a circular hole plate specimen, the critical point where the stress concentration at the edge of the circular hole is most significant under the second-stage peak tensile condition is first identified. Starting from this critical point, a fixed-length effective damage zone is delineated away from the hole wall. This zone is the key area for the generation and propagation of fatigue damage at the hole edge. A dedicated stress extraction path is formed along this extension direction. The distance values ​​from all discrete nodes of the finite element mesh to the hole edge and the maximum principal stress corresponding to each node under the second-stage peak tensile condition are read. A stress weighting index is introduced to perform power-law weighting on the maximum principal stress of each pair of adjacent discrete nodes. The integral approximation of the weighted stress within each adjacent node interval is calculated using trapezoidal numerical integration. The calculation results of all intervals are accumulated piecewise to obtain the total accumulated value of the weighted stress within the damage zone. This total accumulated value is divided by the length of the effective damage zone at the hole edge to achieve stress averaging. Then, the average result is squared based on the stress weighting index. The final calculated value is the local equivalent stress at the edge of the circular hole component. The specific formula is as follows: ; In the formula, and The maximum principal stress at adjacent finite element discrete nodes. and Let be the distance from the edge of the hole to the adjacent finite element discrete node. q is the length of the effective damage zone at the edge of the hole, q is the number of nodes on the stress path at the edge of the hole, and m is the weighting index.

[0039] This method is compatible with discrete node data output by finite element simulation. It does not require obtaining continuous stress functions and can directly rely on engineering simulation results to complete the calculation, accurately characterizing the comprehensive influence of the gradient stress field at the hole edge on fatigue damage.

[0040] Step S13: Determine the damage index of the component to be evaluated in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component to be evaluated in the second stage.

[0041] In this embodiment, determining the damage index of the component to be evaluated in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component to be evaluated in the second stage includes: obtaining the average stress of the component to be evaluated in the second stage according to the control stress and the low-cycle fatigue stress ratio of the component to be evaluated in the second stage; correcting the fatigue damage threshold stress of the component to be evaluated in the second stage using the average stress of the second stage to obtain the corrected threshold stress; and determining the damage index of the component to be evaluated in the second stage based on the control stress, the corrected threshold stress, and the tensile strength of the component to be evaluated in the second stage.

[0042] After selecting the control stress for the second stage, the damage index is calculated. First, the average stress borne by the component under this condition is calculated by combining the determined control stress with the stress ratio corresponding to the second stage of isothermal low-cycle fatigue loading. The specific formula is as follows: ; In the formula, The average stress of the component to be evaluated in the second stage. The low-cycle fatigue stress of the component to be evaluated in the second stage, To control stress.

[0043] Mean stress can change the critical stress level at which a material will suffer fatigue damage. Therefore, it is necessary to use the calculated mean stress to correct the basic fatigue damage threshold stress corresponding to the fully reverse loading condition, so as to obtain the corrected threshold stress that is suitable for the current service conditions with mean stress.

[0044] The formula for obtaining the corrected threshold stress is as follows: ; In the formula, To correct the threshold stress, This represents the fatigue limit corresponding to the second stage of fully reverse loading conditions. This is the average stress correction factor. This represents the average stress in the second stage.

[0045] Then, the second-stage control stress, the threshold stress after the average stress correction, and the tensile strength of the component material under the second-stage temperature conditions are all substituted into the damage index correlation model to calculate the second-stage damage index that matches the actual stress state of the component.

[0046] The formula for obtaining the damage index in the second stage is: ; In the formula, This is the damage index for the second stage. For material parameters, For the control stress of the second stage, For the second phase Corrected threshold stress at temperature For the second phase Tensile strength at temperature The brackets are for Macaulay.

[0047] This damage index is used to characterize the nonlinear development rate of damage accumulation with the number of cycles under the second stage of isothermal low-cycle fatigue loading. By introducing the mean stress correction link, the interference of mean stress on the damage initiation threshold is eliminated. The damage index is solved by combining the control stress under real-time working conditions and the high-temperature mechanical property parameters of the material. It can fit the nonlinear characteristics of accelerated damage accumulation of nickel-based single crystal superalloys under isothermal cyclic loading and avoid the life prediction deviation caused by using a fixed constant damage index.

[0048] It should be noted that the Macaulay brackets satisfy: ; It is understandable that in the formula express .

[0049] Step S14: Based on the nonlinear damage evolution relationship of the second stage, convert the pre-damage of the first stage into the equivalent consumed cycle number under the second stage.

[0050] In the second stage, a nonlinear damage evolution relationship is established under isothermal low-cycle fatigue conditions. This relationship is as follows: ; in, The second stage isothermal low-cycle fatigue damage, where n represents the second stage isothermal low-cycle fatigue cycles. This represents the low-cycle fatigue baseline life under the same second-stage loading conditions under no thermomechanical fatigue pre-damage conditions. This is the second stage of isothermal low-cycle fatigue damage index.

[0051] This relationship describes the nonlinear accumulation of damage with loading cycles using the number of cycles and the damage index as variables. The dimensionless pre-damage value generated by the first stage of thermomechanical fatigue loading is used as an intermediate benchmark for the equivalent transformation of the damage state. This pre-damage value is substituted into the nonlinear damage evolution relationship of the second stage, as shown below: ; In the formula, The equivalent number of cycles consumed corresponds to the first stage of thermomechanical fatigue pre-damage under the second stage of isothermal low-cycle fatigue conditions.

[0052] Next, we perform a reverse solution, eliminating the variables representing the degree of damage within the relational expression to obtain the corresponding number of iterations. The formula for obtaining the equivalent number of iterations consumed is as follows: ; In the formula, The pre-damage of the component to be evaluated in the first stage. This is the damage index for the second stage. For the equivalent number of loops consumed, The reference life of the component to be evaluated in the second stage is the low-cycle fatigue reference life of the component to be evaluated under the same second-stage load without experiencing the first-stage load damage.

[0053] This refers to the equivalent number of cycles consumed under the second-stage isothermal low-cycle fatigue load environment, which is the result of converting the first-stage thermomechanical pre-damage to the second-stage isothermal low-cycle fatigue load environment. Unlike the traditional linear damage superposition method, which simply replaces the damage fraction with an equal amount, this embodiment uses an evolution model adapted to the nonlinear damage development characteristics of the material in the second stage to complete the equivalent damage conversion across load types. It fully considers the difference in damage growth rate of nickel-based single-crystal superalloys under different fatigue loads, restores the nonlinear consumption effect of thermomechanical pre-damage on the subsequent isothermal low-cycle fatigue life, and provides conversion parameters that fit the actual damage evolution law of the material for the subsequent remaining life calculation, reducing the life prediction distortion caused by the linear equivalence assumption.

[0054] Step S15: Predict the low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage based on the difference between the reference life of the component under evaluation in the second stage and the equivalent number of cycles consumed; wherein, the component under evaluation is an alloy component that has undergone a first stage load and a second stage load in sequence, the first stage is the thermomechanical fatigue pre-loading stage, and the second stage is the isothermal low-cycle fatigue loading stage.

[0055] After converting the equivalent number of cycles consumed under the first stage of thermomechanical fatigue pre-damage to the second stage of isothermal low-cycle fatigue load, the complete reference isothermal low-cycle fatigue cycle count that the component can withstand under the corresponding working condition in the second stage without pre-damage is retrieved. The reference life value of the second stage is then subtracted from the converted equivalent number of cycles consumed. The difference between the two is the number of second-stage isothermal low-cycle fatigue cycles that the component can continue to withstand after accumulating micro-defects due to the previous thermomechanical fatigue pre-damage. The specific formula is as follows: ; In the formula, This refers to the remaining low-cycle fatigue life of the component to be evaluated after thermomechanical fatigue pre-damage, i.e., the number of second-stage isothermal low-cycle fatigue cycles it can continue to withstand. For the equivalent number of loops consumed, The baseline life of the component to be evaluated in the second stage.

[0056] Understandably, the formula for obtaining the equivalent number of loops consumed can be derived from this. The formula is: ; Then according to From the formula, we can derive... The formula is: ; This value is directly used as the prediction result of the low-cycle fatigue remaining life of the component after thermomechanical fatigue pre-damage. The calculation logic strictly matches the actual service load sequence of the component first undergoing thermomechanical fatigue pre-loading and then long-term operation under isothermal low-cycle fatigue load. It relies on the equivalent consumption cycle number obtained by nonlinear conversion to carry out the difference calculation, abandoning the coarse calculation method of traditional linear damage deduction. It can accurately reflect the degree of loss of the subsequent isothermal fatigue bearing capacity due to the early cold and heat coupling pre-damage. The output remaining life result has a higher degree of matching with the fatigue test data of nickel-based single crystal high-temperature alloy samples with pre-damage.

[0057] The beneficial effects of this application are as follows: This application determines the pre-damage of the component under evaluation in the first stage as the ratio between the pre-loading cycle number and the reference life in the first stage; determines the control stress in the second stage according to the sample type of the component under evaluation; determines the damage index of the component under evaluation in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component under evaluation in the second stage; converts the pre-damage in the first stage into the equivalent consumed cycle number in the second stage based on the nonlinear damage evolution relationship in the second stage; predicts the low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage based on the difference between the reference life and the equivalent consumed cycle number in the second stage; wherein, the component under evaluation is an alloy component that has successively experienced the first stage load and the second stage load, the first stage is the thermomechanical fatigue pre-loading stage, and the second stage is the isothermal low-cycle fatigue loading stage. Therefore, this application directly characterizes the first-stage thermomechanical fatigue pre-damage by using the ratio of the first-stage pre-loading cycle number to the corresponding baseline thermomechanical fatigue life. This eliminates the need to accumulate multiple damage components cycle by cycle, simplifying the calculation process for the first-stage damage. The second-stage control stress is selected based on the sample type, matching the actual damage control area of ​​components with different geometries and reducing prediction bias caused by using only a uniform nominal stress. Furthermore, by combining the second-stage control stress, fatigue damage threshold stress, and tensile strength to calculate the damage index, the damage index can dynamically change with the actual stress state of the component, accurately reflecting the damage of nickel-based single-crystal superalloys at high temperatures. The nonlinear development law, based on the nonlinear damage evolution relationship of the second stage, completes the conversion of the first stage pre-damage to the equivalent consumed cycle number under the second stage load, replacing the traditional Miner linear damage criterion's calculation method of directly deducting the life fraction. It can restore the nonlinear loss effect of thermomechanical fatigue pre-damage on the subsequent isothermal low-cycle fatigue life. Finally, the remaining life is obtained by subtracting the equivalent consumed cycle number from the second stage reference life. The calculation logic fits the actual service load sequence of the component first undergoing thermomechanical fatigue and then isothermal low-cycle fatigue, improving the consistency between the low-cycle fatigue remaining life prediction results of components with thermomechanical pre-damage and the experimental measured data.

[0058] The following description uses a round bar specimen as an example to illustrate this application. For the round bar specimen, the first stage is thermomechanical fatigue preloading. The maximum stress in the round bar specimen during the first stage of thermomechanical fatigue is 650 MPa, the highest temperature is 980℃, the lowest temperature is 490℃, the temperature change rate is 70℃ / s, and the stress ratio is 0.05. The reference thermomechanical fatigue life of the round bar specimen under this condition is... The number of cycles was 776. This refers to the number of thermomechanical fatigue cycles in the first stage of a two-stage test for round bar specimens under different preload conditions. The numbers are 77, 271, 349, and 427 cycles.

[0059] First stage thermomechanical fatigue pre-damage of round bar specimens Represented as: ; in, This represents the first stage of thermomechanical fatigue pre-damage for the round bar specimen. This represents the number of pre-loading cycles for the first stage of thermomechanical fatigue testing on the round bar specimen. This is the reference thermomechanical fatigue life of the round bar specimen under the same thermomechanical fatigue conditions.

[0060] The second stage of the round bar specimen was subjected to isothermal low-cycle fatigue loading. The low-cycle fatigue temperature in the second stage was 980℃, the nominal maximum stress was 750MPa, and the stress ratio was 0.05. Under conditions without thermomechanical fatigue pre-damage, the reference life of the round bar specimen in the second stage of low-cycle fatigue was... for cycles.

[0061] Since the circular bar specimen has geometric continuity and there is no stress concentration at the hole edge within the gauge length, the control stress for the second stage of low-cycle fatigue is taken as the nominal maximum stress, i.e.: ; in, The stress is the control stress for the second stage of low-cycle fatigue in the round bar specimen. This represents the nominal maximum stress during the second stage of low-cycle fatigue in the round bar specimen.

[0062] When considering the mean stress correction, the mean stress of the round bar specimen in the second stage is: ; The second-stage fatigue damage threshold stress for the round bar specimen is: ; in, The fatigue limit is given by the fully reverse loading condition at the second stage temperature, where b is the average stress correction factor. This represents the average stress in the second stage of the round bar specimen.

[0063] The low-cycle fatigue damage index of the round bar specimen in the second stage is: ; Where 'a' is the material damage parameter, The tensile strength of the material at the second stage temperature. The fatigue damage threshold stress of the round bar specimen after mean stress correction is given.

[0064] Based on the evolution relationship of low-cycle fatigue damage in the second stage, the pre-damage of thermomechanical fatigue in the first stage is... Equivalent to the number of cycles consumed under the second stage of low-cycle fatigue conditions. ,satisfy: ; Find: ; The remaining low-cycle fatigue life of the round bar specimen after thermomechanical fatigue pre-damage is: ; Will After substituting, we get: ; This formula is a prediction formula for the remaining life of a round bar sample when it enters the second stage of isothermal low-cycle fatigue after thermomechanical fatigue pre-damage.

[0065] It is understandable that the superscript RB in the above formulas indicates that the specimen type of the component to be evaluated is a circular hole plate specimen.

[0066] The following description uses a circular hole plate specimen as an example to illustrate this application. For the circular hole plate specimen, the first stage is also thermomechanical fatigue preloading. The nominal maximum stress of the first stage thermomechanical fatigue of the circular hole plate specimen is 550 MPa, the highest temperature is 980℃, the lowest temperature is 490℃, the temperature change rate is 70℃ / s, and the stress ratio is 0.05. The reference thermomechanical fatigue life of the circular hole plate specimen under this condition is... The number of cycles was 1684. This represents the number of thermomechanical fatigue preloading cycles in the first stage of a two-stage test on a circular hole plate specimen. The cycle is 252, 421, 757, or 1094.

[0067] The first stage of thermomechanical fatigue pre-damage of a circular hole plate specimen is represented as follows: ; in, This represents the first stage of thermomechanical fatigue pre-damage for the circular hole plate specimen. This represents the number of thermomechanical fatigue preloading cycles for the first stage of the circular hole plate specimen. This is the benchmark thermomechanical fatigue life of the round hole plate specimen under the same thermomechanical fatigue conditions.

[0068] The second stage of the circular hole plate specimen was subjected to isothermal low-cycle fatigue loading. The low-cycle fatigue temperature in the second stage was 980℃, the nominal maximum stress was 600MPa, and the stress ratio was 0.05. Under conditions without thermomechanical fatigue pre-damage, the reference life of the second stage low-cycle fatigue of the circular hole plate specimen was determined. for cycle.

[0069] Unlike round bar specimens, round hole plate specimens exhibit significant stress concentration at the hole edge, and the second-stage low-cycle fatigue damage is primarily controlled by the localized high-stress zone at the hole edge. Therefore, the nominal maximum stress is not directly used as the controlling stress for the second-stage low-cycle fatigue of round hole plate specimens; instead, the equivalent stress at the hole edge is employed. ; like Figure 4 As shown, the local equivalent stress at the hole edge is determined by the path of the maximum principal stress at the hole edge under the peak tensile state of low-cycle fatigue in the second stage. Let the distribution of the maximum principal stress extracted from the critical point at the hole edge along the direction away from the hole edge be: ; Where r is the distance from the path point to the critical point at the edge of the hole, and the superscript (2) indicates that the stress distribution corresponds to the second stage of low-cycle fatigue peak tensile state. Let the effective damage zone length at the edge of the hole be... If the stress weighting exponent is m, then the local equivalent stress at the hole edge is: ; In this embodiment, the stress weighting index Take 4, the effective damage zone length at the hole edge Desirable ,in The radius of the circular hole is given. These values ​​characterize the dominant effect of the high-stress region at the hole edge on fatigue damage. Related studies indicate that the maximum principal stress in a circular hole plate specimen is concentrated in the hole edge region, and the local equivalent stress at the hole edge can be used to reflect the influence of the high-stress region at the hole edge on the second stage of low-cycle fatigue damage.

[0070] If the local equivalent stress at the hole edge is calculated using discrete nodal data from the finite element method, then several nodes are selected along the hole edge path, with the distance from each node to the critical point at the hole edge being... The maximum principal stress at the node is The local equivalent stress at the edge of the hole can be written in trapezoidal integral form as follows: ; Where q is the number of nodes on the stress path at the hole edge. and These represent the distances from adjacent nodes to the critical point on the edge of the hole. and These represent the maximum principal stresses at the corresponding nodes.

[0071] When considering the mean stress correction, the mean stress in the second stage of the circular hole plate specimen is: ; The second-stage fatigue damage threshold stress for the circular hole plate specimen is: ; The low-cycle fatigue damage index of the circular hole plate specimen in the second stage is: ; in, For the local equivalent stress at the edge of the hole, The fatigue damage threshold stress is corrected for by mean stress. denoted as σ, where σ is the tensile strength of the material at the second-stage temperature, and α is the material damage parameter.

[0072] Based on the evolution relationship of low-cycle fatigue damage in the second stage, the pre-damage of thermomechanical fatigue in the first stage is... Equivalent to the number of cycles consumed under the second stage of low-cycle fatigue conditions. ,satisfy: ; Find: ; The remaining low-cycle fatigue life of the circular hole plate specimen after thermomechanical fatigue pre-damage is: ; Will After substituting, we get: ; This formula is a prediction formula for the remaining life of a circular hole plate sample when it enters the second stage of isothermal low-cycle fatigue after thermomechanical fatigue pre-damage.

[0073] It is understandable that the formulas above containing the superscript CP indicate that the specimen type of the component to be evaluated is a circular hole plate specimen.

[0074] See Figure 5 As shown in the figure, this application discloses a device for predicting the low-cycle fatigue life of alloy components, comprising: The pre-damage determination module 11 is used to determine the ratio between the number of preload cycles of the component to be evaluated in the first stage and the reference life of the first stage as the pre-damage of the component to be evaluated in the first stage. The stress determination module 12 is used to determine the control stress for the second stage based on the specimen type of the component to be evaluated. The damage index determination module 13 is used to determine the damage index of the component to be evaluated in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component to be evaluated in the second stage. The equivalent conversion module 14 is used to convert the pre-damage of the first stage into the equivalent consumed cycle number under the second stage based on the nonlinear damage evolution relationship of the second stage. The life prediction module 15 is used to predict the low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage based on the difference between the baseline life of the component under evaluation in the second stage and the equivalent consumed cycles. The component to be evaluated is an alloy component that has undergone a first stage load and a second stage load in sequence. The first stage is a thermomechanical fatigue preloading stage, and the second stage is an isothermal low-cycle fatigue loading stage.

[0075] Furthermore, embodiments of this application also provide an electronic device. Figure 6 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content of the diagram should not be construed as limiting the scope of this application.

[0076] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Specifically, it may include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 stores a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the low-cycle fatigue life prediction method for alloy components performed by the electronic device disclosed in any of the foregoing embodiments.

[0077] In this embodiment, the power supply 23 is used to provide operating voltage for various hardware devices on the electronic device; the communication interface 24 can create a data transmission channel between the electronic device and external devices, and the communication protocol it follows can be any communication protocol applicable to the technical solution of this application, and is not specifically limited here; the input / output interface 25 is used to acquire external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs, and is not specifically limited here.

[0078] The processor 21 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 21 may be implemented using at least one hardware form selected from DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). The processor 21 may also include a main processor and a coprocessor. The main processor, also known as a CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 21 may integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 21 may also include an AI (Artificial Intelligence) processor, which is used to handle computational operations related to machine learning.

[0079] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or optical disk, etc. The resources stored on it include operating system 221, computer program 222 and data 223, etc., and the storage method can be temporary storage or permanent storage.

[0080] The operating system 221 manages and controls the various hardware devices and computer programs 222 on the electronic device to enable the processor 21 to perform calculations and processing on the massive amounts of data 223 in the memory 22. The operating system can be Windows, Unix, Linux, etc. The computer program 222, in addition to including a computer program capable of performing the low-cycle fatigue life prediction method for alloy components executed by the electronic device as disclosed in any of the foregoing embodiments, may further include computer programs capable of performing other specific tasks. The data 223 may include data received by the electronic device from external devices, as well as data collected by its own input / output interface 25.

[0081] Furthermore, this application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned method for predicting the low-cycle fatigue life of alloy components. Specific steps of this method can be found in the corresponding content disclosed in the foregoing embodiments, and will not be repeated here.

[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0083] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application. The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly in hardware, software modules executed by a processor, or a combination of both. The software module may be located in random access memory (RAM), memory, read-only memory (ROM), electrically programmable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), register, hard disk, removable disk, CD-ROM (Compact Disc Read-Only Memory), or any other form of storage medium known in the art.

[0084] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0085] The above provides a detailed description of the method, apparatus, equipment, and medium for predicting the low-cycle fatigue life of alloy components provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only intended to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for predicting the low-cycle fatigue life of alloy components, characterized in that, include: The ratio between the number of preload cycles of the component to be evaluated in the first stage and the baseline lifetime in the first stage is determined as the pre-damage of the component to be evaluated in the first stage. The control stress for the second stage is determined based on the specimen type of the component to be evaluated; The damage index of the component under evaluation in the second stage is determined based on the control stress and the fatigue damage threshold stress and tensile strength of the component under evaluation in the second stage. Based on the nonlinear damage evolution relationship of the second stage, the pre-damage of the first stage is equivalently converted into the equivalent number of cycles consumed under the second stage. The low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage is predicted based on the difference between the baseline life of the component under evaluation in the second stage and the equivalent number of cycles consumed. The component to be evaluated is an alloy component that has undergone a first stage load and a second stage load in sequence. The first stage is a thermomechanical fatigue preloading stage, and the second stage is an isothermal low-cycle fatigue loading stage. The nonlinear damage evolution relationship is as follows: ； in, The second stage isothermal low-cycle fatigue damage, where n represents the second stage isothermal low-cycle fatigue cycles. This represents the low-cycle fatigue baseline life under the same second-stage loading conditions under no thermomechanical fatigue pre-damage conditions. The second stage isothermal low-cycle fatigue damage index; The nonlinear damage evolution formula describes the law of nonlinear accumulation of damage with loading cycles using the number of cycles and the damage index as variables. The dimensionless pre-damage value generated by the first stage of thermomechanical fatigue loading is used as an intermediate benchmark for the equivalent transformation of the damage state. The pre-damage value is substituted into the nonlinear damage evolution formula, as shown below: ； In the formula, The equivalent number of cycles consumed corresponds to the first stage of thermomechanical fatigue pre-damage under the second stage of isothermal low-cycle fatigue conditions. The pre-damage of the component to be evaluated in the first stage; The formula for obtaining the equivalent number of cycles consumed is: ； Wherein, the reference life of the component to be evaluated in the second stage is the low-cycle fatigue reference life of the component to be evaluated under the same second stage load without experiencing the first stage load damage condition.

2. The method for predicting the low-cycle fatigue life of alloy components according to claim 1, characterized in that, The determination of the control stress in the second stage based on the specimen type of the component to be evaluated includes: If the specimen type of the component to be evaluated is a round bar specimen, then the nominal maximum stress of the component to be evaluated in the second stage is determined as the control stress of the second stage. If the specimen type of the component to be evaluated is a flat plate specimen with a circular hole, the local equivalent stress at the hole edge of the component to be evaluated is obtained by the continuous integration method or the finite element discretization method, and the local equivalent stress at the hole edge of the component to be evaluated is determined as the control stress of the second stage.

3. The method for predicting the low-cycle fatigue life of alloy components according to claim 2, characterized in that, The local equivalent stress at the hole edge of the component to be evaluated is obtained using the continuous integration method, including: The effective damage zone of the hole edge is delineated outward from the critical point where the stress at the edge of the circular hole of the component to be evaluated is the point where the stress is the greatest. In the peak tensile state of the second stage, the maximum principal stress is extracted from the critical point of the edge of the circular hole of the component to be evaluated in the direction away from the edge of the hole. A stress weighting index is introduced to apply a power weight to the maximum principal stress, and the weighted stress is integrated within the effective damage zone of the hole edge. The integrated result is then processed using the length of the effective damage zone of the hole edge and the stress weighting index to obtain the local equivalent stress at the hole edge of the component to be evaluated.

4. The method for predicting the low-cycle fatigue life of alloy components according to claim 2, characterized in that, The local equivalent stress at the hole edge of the component to be evaluated is obtained using the finite element discretization method, including: The effective damage zone of the hole edge is delineated outward from the critical point where the stress at the edge of the circular hole of the component to be evaluated is the critical point where the stress at the edge of the circular hole is the greatest. In the peak tensile state of the second stage, the distances of all finite element discrete nodes from the edge of the hole and the maximum principal stress of the corresponding nodes are extracted from the critical point of the edge of the circular hole of the component to be evaluated in the direction away from the edge of the hole. A stress weighting index is introduced to perform power-law weighting on the maximum principal stress of adjacent discrete nodes. The weighted stress within the adjacent node interval is summed piecewise using a trapezoidal integral method. The summed result is then processed using the length of the effective damage zone at the hole edge and the stress weighting index to obtain the local equivalent stress at the hole edge of the component to be evaluated.

5. The method for predicting the low-cycle fatigue life of alloy components according to claim 1, characterized in that, The determination of the damage index of the component under evaluation in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component under evaluation in the second stage includes: The average stress of the component under evaluation in the second stage is obtained based on the control stress and the low-cycle fatigue stress ratio of the component under evaluation in the second stage. The fatigue damage threshold stress of the component to be evaluated in the second stage is corrected by using the average stress of the second stage to obtain the corrected threshold stress. The damage index of the component to be evaluated in the second stage is determined based on the control stress, the corrected threshold stress, and the tensile strength of the component to be evaluated in the second stage.

6. The method for predicting the low-cycle fatigue life of alloy components according to claim 5, characterized in that, The formula for obtaining the corrected threshold stress is as follows: ； In the formula, To correct the threshold stress, This represents the fatigue limit corresponding to the second stage of fully reverse loading conditions. This is the average stress correction factor. The average stress in the second stage; Accordingly, the formula for obtaining the damage index in the second stage is: ； In the formula, This is the damage index for the second stage. For material parameters, For the control stress of the second stage, For the second phase Corrected threshold stress at temperature For the second phase Tensile strength at temperature.

7. A device for predicting the low-cycle fatigue life of alloy components, characterized in that, The steps for implementing the low-cycle fatigue life prediction method for alloy components as described in any one of claims 1 to 6 include: A pre-damage determination module is used to determine the ratio between the number of preload cycles of the component to be evaluated in the first stage and the reference life of the first stage as the pre-damage of the component to be evaluated in the first stage. The stress determination module is used to determine the control stress for the second stage based on the specimen type of the component to be evaluated; The damage index determination module is used to determine the damage index of the component to be evaluated in the second stage based on the control stress and the fatigue damage threshold stress and tensile strength of the component to be evaluated in the second stage. The equivalent conversion module is used to convert the pre-damage of the first stage into the equivalent number of consumed cycles in the second stage based on the nonlinear damage evolution relationship of the second stage. The life prediction module is used to predict the low-cycle fatigue remaining life of the component under evaluation after thermomechanical fatigue pre-damage based on the difference between the baseline life of the component under evaluation in the second stage and the equivalent number of cycles consumed. The component to be evaluated is an alloy component that has undergone a first stage load and a second stage load in sequence. The first stage is a thermomechanical fatigue preloading stage, and the second stage is an isothermal low-cycle fatigue loading stage.

8. An electronic device, characterized in that, include: Memory is used to store computer programs; A processor for executing the computer program to implement the steps of the low-cycle fatigue life prediction method for alloy components as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, Used to store a computer program; wherein, when the computer program is executed by a processor, it implements the steps of the low-cycle fatigue life prediction method for alloy components as described in any one of claims 1 to 6.

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