A method and system for predicting the fatigue life of a thin-walled structure by jump buckling

Abstract

A thin-walled structure jump buckling fatigue life prediction method and system belong to the structural fatigue life evaluation method. The method can quickly and accurately predict the fatigue life of the structure under the thermal acoustic environment, successfully reveals the double damage mechanism of structure wave accumulation and jump mutation under thermal acoustic load. The method can not only accurately capture the random time and amplitude characteristics of jump buckling, but also control the life prediction error within the engineering acceptable range while ensuring the calculation efficiency, providing an efficient and robust calculation tool for the fatigue resistance design and reliability evaluation of thin-walled structures in the thermal acoustic environment.

Description

Technical Field

[0001] This invention pertains to structural fatigue life assessment methods, specifically designing a fatigue life prediction method and system based on measured stress-time history for structures undergoing random snap-through under thermo-acoustic loading. Background Technology

[0002] Thin-walled structures such as high-speed aircraft skins and rocket fairings are prone to thermal buckling under the combined effects of high temperatures and strong noise, leading to a type of extreme point instability: jump buckling, also known as abrupt buckling. In an elastic system, when a certain load is reached, the system may jump from an equilibrium state to a non-proximity equilibrium state. Jump buckling causes a large jump in stress, far exceeding the background stress fluctuation, thus drastically accelerating the accumulation of fatigue damage.

[0003] Traditional fatigue analysis methods (such as rainflow counting and Miner's linear accumulation criterion) can only handle continuous stress fluctuations, failing to distinguish between ordinary fluctuation and jump buckling behavior, and even less able to quantify the damage caused by jump buckling alone. Furthermore, existing methods require complete simulation of all stress cycles, resulting in high computational costs and making it impossible to quickly estimate fatigue life using statistical parameters such as jump rate. Therefore, there is an urgent need for a method that can automatically identify jump buckling, calculate fluctuation damage rates and jump buckling damage rates separately, and rapidly predict fatigue life based on safety set boundaries and jump buckling rates. Summary of the Invention

[0004] This invention provides a method and system for predicting the skip buckling fatigue life of thin-walled structures. It can automatically extract skip buckling events from stress time history, separate the fluctuation damage and skip buckling damage of thin-walled structures under combined thermoacoustic loads, and use the linear intersection method to quickly predict the expected fatigue life, thus solving the problem that existing technologies cannot efficiently handle skip buckling fatigue.

[0005] The technical solution of the present invention is as follows: A method for predicting the skipped buckling fatigue life of a thin-walled structure, comprising the following steps:

[0006] Step 1: Calculate the critical buckling temperature of the components and the entire structure;

[0007] Step 2: Perform transient dynamic analysis by applying a combined thermo-acoustic load;

[0008] Step 3: Detect jump buckling behavior;

[0009] Step 4: Detection of structural damage rate and jump buckling rate; specifically including the following sub-steps:

[0010] Step 4.1, Fluctuation Damage Rate Detection: In the original time-stress sequence, data points within a certain time window before and after each jump buckling occurrence are removed to obtain the pure wave stress sequence. ;right Peak and valley values ​​were extracted, and several stress cycles were obtained using the rainflow counting method. Each cycle had a stress range R and a mean value M. The damage for each cycle was calculated using the material's SN curve and mean stress correction. The total fluctuation damage is obtained by summing all the cyclic damages. Simultaneously calculate the total time of fluctuation data. The fluctuation damage rate was obtained. ;in, It is the start time of the fluctuating load data; It is the termination time of the fluctuating load data;

[0011] Step 4.2, Single jump flexion injury rate Detection: For each detected jump buckling location in the time stress history, the average stress within each time window before and after the jump buckling is taken to obtain the stress level before the jump buckling. and stress level after jump buckling The stress range of this jump buckling average stress ; Calculate the damage of this jump-buckling cycle The damage is calculated for all detected jump buckling events, and the average damage for all jump buckling events is taken to obtain the single jump buckling damage.

[0012] 4.3 Jump buckling rate Calculation: Use the program to determine the number of buckling bounces in the original time-stress history. If the number of buckling bounces... ,but ,in, t first The moment when the first jump buckling occurs. t last The time of the last jump buckling is μ, which is the number of jump bucklings divided by the total time span of jump bucklings; if ,but ,in t start The moment when the load history begins. t end This represents the end time of the load history; if the program detects no buckling time jump in the original time-stress history, then output... = 0;

[0013] Step 5: Construct the safety set boundary line, and apply the total damage formula. Construct the safety set boundary line for the cumulative damage model; set D=1 to obtain the safety set boundary line. , among which, among which Let t be the initial injury, t be time, and M be the number of jump bucklings. For fluctuating damage rate, This represents the single-jump flexion injury rate.

[0014] Step 6: Calculate the expected failure time and solve the linear equation. The intersection point with the safety set boundary yields the expected fatigue life, which is the expected failure time. .

[0015] Further, step 1 specifically involves: establishing a finite element model of the complex structural components and dividing the mesh; based on the structural geometric features and boundary conditions, using shell elements or solid elements for discretization modeling to ensure that the mesh density can accurately capture the thermal buckling modes and stress gradients in order to calculate the critical buckling temperature of the structure.

[0016] Furthermore, step 2 specifically involves: applying a uniform temperature field to the structure to simulate the influence of the thermal environment on the structural material properties and stress; then applying the measured noise pressure time history to the surface of the structure, which serves as the external normal uniform pressure load on the surface of the finite element model.

[0017] Furthermore, step 3 specifically involves: after completing the transient dynamic analysis of the combined thermo-acoustic loading, identifying the nodes or elements where the maximum Von Mises stress or principal stress occurs throughout the entire time history; after determining the location of the node or element, deriving the time stress history of that node or element; and calculating the difference sequence between adjacent stress points in the time stress history. dS Find its standard deviation and set a threshold ,in The empirical coefficient is 2~5; find all The location is used as the candidate time point for the jump buckling time; the time interval is less than the minimum time interval threshold. Multiple candidate points are merged into a single jump buckling, and the jump buckling moment is recorded within the program. and number of jump flexion .

[0018] Furthermore, step 5 specifically involves:

[0019] The intercept of the safety set boundary line on the vertical axis Expressed as: the number of jump bucklings required for a structure to fail only through jump buckling, expressed as the intercept on the horizontal axis. It is expressed as the time required for the structure to fail if it only experiences pure fluctuations.

[0020] Furthermore, step 6 specifically involves:

[0021] In the time-jump buckling count plane, i.e., the expected plane with time on the horizontal axis and jump buckling count on the vertical axis, the expected increase in jump buckling count follows a linear curve. The x-coordinate of the intersection point of this straight line and the safety set boundary line is the expected failure time. ;when and hour, ,like or The expected failure time is equal to the time required for the structure to fail due to simple fluctuations.

[0022] Furthermore, the method also includes step 7, result output and visualization: outputting the fluctuation damage rate. Single jump flexion injury Jump buckling rate Expected failure time This visually demonstrates the randomness of the jump buckling process and the principles of lifetime prediction.

[0023] A system for predicting the random jump buckling fatigue life of a thermal buckling plate, the system being used to implement the prediction method described above; the system includes:

[0024] Data acquisition module: Acquires stress time history data of the structure under combined thermo-acoustic loads;

[0025] Critical buckling temperature calculation module: Implements step 1, calculates the critical buckling temperature of a component or the whole structure using the finite element method, and determines the temperature threshold at which the structure will buckle.

[0026] Thermo-acoustic joint loading and transient analysis module: Implements step 2, applies a uniform temperature field and Gaussian white noise sound pressure time history to the structure, performs transient dynamic analysis, and obtains the dynamic response of the structure;

[0027] Jump buckling detection module: Implements step 3, automatically identifies jump buckling events from stress time history, and records the jump buckling time and the number of jump bucklings;

[0028] Damage rate and jump buckling rate detection module: Implements step 4 and includes three sub-modules:

[0029] The fluctuation damage rate calculation submodule performs rainflow counting and damage accumulation on pure fluctuation stress and calculates the fluctuation damage per unit time.

[0030] Jump buckling injury rate calculation submodule: Constructs large-scale stress cycles for each jump buckling event and calculates the average injury of a single jump buckling;

[0031] Jump buckling rate calculation submodule: Calculates the average rate at which jump buckling occurs based on the number of jump bucklings and the time span;

[0032] Safety set boundary construction module: Implements step 5, based on the total damage formula. Construct the safety set boundary line for the cumulative damage model;

[0033] Expected failure time calculation module: Implement step 6, solve the straight line The intersection point with the boundary of the safety set yields the expected fatigue life.

[0034] Furthermore, the system also includes a result output and visualization module: implementing step 7, outputting fluctuation damage rate, jump buckling damage rate, jump buckling rate, and expected lifetime, and plotting the safety set boundary, straight line.

[0035] The beneficial effects of this invention are as follows: Addressing the problem that traditional fatigue analysis methods (such as rainflow counting + Miner linear accumulation criterion) can only handle continuous stress fluctuations, cannot distinguish between ordinary fluctuations and jump buckling behavior, and cannot quantify the damage caused by jump buckling alone, this invention proposes a fatigue life calculation method for structures exhibiting jump buckling behavior. This method can quickly and accurately predict the fatigue life of structures experiencing frequent random jump buckling events under thermoacoustic conditions, successfully revealing the dual damage mechanism of structural fluctuation accumulation and jump abrupt changes under thermoacoustic loading.

[0036] The calculation results show that this method can not only accurately capture the random moment and amplitude characteristics of the buckling, but also control the lifetime prediction error within an acceptable range while ensuring computational efficiency. It provides an efficient and robust calculation tool for the fatigue design and reliability assessment of thin-walled structures in thermoacoustic environments. Attached Figure Description

[0037] Figure 1 This is a flowchart of a fatigue cumulative damage model for thin-walled structures under thermoacoustic conditions.

[0038] Figure 2 This is a schematic diagram of applying thermoacoustic loads to a structure.

[0039] Figure 3 The extracted structure's time-stress history response under conditions of buckling coefficient S=1.2 and sound pressure level SPL=148dB (S=1.2, SPL=148dB).

[0040] Figure 4 This is the corresponding structural cumulative damage model. Detailed Implementation

[0041] The technical solution of the present invention will be described in detail below:

[0042] A method for predicting the skipped buckling fatigue life of a thin-walled structure includes the following steps: Figure 1 As shown, the steps are as follows:

[0043] Step 1: Calculate the critical buckling temperature of the components and the entire structure;

[0044] Step 2 involves applying combined thermal and acoustic loads to the structure to perform transient dynamic analysis;

[0045] Step 3: Detect jump buckling behavior;

[0046] Step 4: Detection of structural damage rate and jump buckling rate;

[0047] Step 5: Construct the boundary line of the safe set;

[0048] Step 6: Calculate the estimated failure time;

[0049] The specific process is as follows: Figure 1 As shown:

[0050] Step 1: Calculate the critical buckling temperature of the component or the entire mechanism:

[0051] Finite element models are established and meshed for complex structural components. Based on the structural geometry and boundary conditions, shell or solid elements are used for discretization modeling to ensure that the mesh density can accurately capture the thermal buckling modes and stress gradients, so as to correctly calculate the critical buckling temperature of the structure.

[0052] Step 2 involves applying a combined thermo-acoustic load to the structure for transient dynamic analysis:

[0053] First, a uniform temperature field is applied to the structure to simulate the influence of the thermal environment on the structural material properties and stress. Then, the measured noise pressure time history is applied to the surface of the structure. This sound pressure time history can be used as an external normal uniform pressure load on the surface of the structure, and applied to the surface of the finite element model (such as skin and panel).

[0054] Step 3: Detect jump buckling behavior:

[0055] After completing the transient dynamic analysis of the combined thermo-acoustic loading, locate the nodes or elements where the maximum Von Mises stress or principal stress occurs throughout the entire time history. Once this critical location is identified, derive the time-stress history of that node. This history records the complete stress fluctuations at the critical point under thermo-acoustic loading, including both background high-frequency random fluctuations and potentially large-scale snap-through buckling characteristics caused by thermal buckling instability. This time-stress history will serve as the foundational input data for subsequent step five (snap-through buckling event detection, separation of fluctuation and snap-through buckling damage, and fatigue life prediction). To detect the severity of stress changes in the data, calculate the difference sequence between adjacent stress points. dS Find its standard deviation and set a threshold ,in The empirical coefficient is 2-5. Find all The location is used as the candidate time point for jump buckling. To prevent a single jump buckling from being judged as multiple jump bucklings by the program, resulting in an artificially high jump buckling rate, the time interval is set to be less than the minimum time interval threshold. Multiple candidate points are merged into a single jump buckling, and the jump buckling moment is recorded within the program. and total number of jump flexion .

[0056] Step 4: Detection of structural damage rate and jump buckling rate.

[0057] 4.1 Fluctuation Damage Rate Detection:

[0058] In the original time-stress sequence, data points within a certain time window (e.g., 0.05 seconds) before and after each jump buckling occurrence are removed to obtain the pure wave stress sequence. .right Peak and valley values ​​were extracted, and several stress cycles were obtained using the rainflow counting method (each cycle has a stress range R and a mean M). Damage for each cycle was calculated using the material's SN curve and mean stress correction (such as SWT or Goodman). The total fluctuation damage is obtained by summing all the cyclic damages. Simultaneously calculate the total time of fluctuation data. The fluctuation damage rate was obtained. ;in, The fluctuation is the start time of the load data; It is the termination time of the fluctuating load data.

[0059] 4.2 Jump-bending injury rate Detection:

[0060] For each detected jump buckling location in the time stress history, the average stress within a 0.05-second window before and after the jump buckling is taken to obtain the stress level before the jump buckling. and stress level after jump buckling This buckling jump is considered as a large-scale stress cycle, with a stress range of... Mean stress Calculate the damage during this jump-buckling cycle. The damage is calculated for all detected jump buckling events, and the average damage for all jump buckling events is taken to obtain the single jump buckling damage.

[0061] 4.3 Jump buckling rate calculate:

[0062] The program determines the number of buckling jumps in the original time-stress history. If the number of buckling jumps... ,but This is calculated by dividing the number of jump bucklings by the total time span during which jump bucklings occur. If ,but If the program detects that there is no jump in buckling time in the original time-stress history, then output... = 0.

[0063] Step 5: Construct the boundary of the security set:

[0064] The formula for calculating total damage is: ,in Let D be the initial damage (usually taken as 0), t be time, and M be the number of jump bucklings. Setting D=1 yields the straight line of the safety set boundary. As shown in the attached diagram. Figure 4 This shows the intercept of the line on the vertical axis. Expressed as: the number of jump bucklings required for a structure to fail only through jump buckling, expressed as the intercept on the horizontal axis. It is expressed as the time required for the structure to fail if it only experiences pure fluctuations.

[0065] Step 6: Calculate the expected failure time :

[0066] In the time-jump buckling count plane, the expected increase in the number of jump bucklings follows a linear curve. The x-coordinate of the intersection point of this straight line and the safety set boundary line is the expected failure time. .when and hour, ,like or The expected failure time is equal to the time required for the structure to fail under simple fluctuations. .

[0067] Step 7: Results Output and Visualization

[0068] Output the fluctuation damage rate via program. Single jump flexion injury Jump buckling rate Expected failure time (in seconds or hours), visually demonstrating the randomness of the jump buckling process and the principle of life prediction.

[0069] System modules:

[0070] Data acquisition module: Acquires stress-time history data (time, stress) of the structure under combined thermo-acoustic loading, providing input for subsequent analysis.

[0071] Critical buckling temperature calculation module: Implements step 1, calculates the critical buckling temperature of the component or whole structure using the finite element method, and determines the temperature threshold at which the structure will buckle.

[0072] Thermo-acoustic combined loading and transient analysis module: Implements step 2, applies a uniform temperature field and Gaussian white noise sound pressure time history to the structure, performs transient dynamic analysis, and obtains the dynamic response of the structure.

[0073] Jump buckling detection module: Implements step 3, automatically identifies jump buckling events from the stress-time history, and records the jump buckling time and the number of jump bucklings.

[0074] Damage rate and jump buckling rate detection module: Implements step 4 and includes three sub-modules:

[0075] The fluctuation damage rate calculation submodule performs rainflow counting and damage accumulation on pure fluctuation stress, and calculates the fluctuation damage per unit time.

[0076] Jump buckling damage rate calculation submodule: Constructs large-scale stress cycles for each jump buckling event and calculates the average damage of a single jump buckling.

[0077] Jump buckling rate calculation submodule: Calculates the average rate at which jump buckling occurs based on the number of jump bucklings and the time span.

[0078] Safety set boundary construction module: Implements step 5, based on the total damage formula. Construct the safety set boundary line for the cumulative damage model.

[0079] Expected failure time calculation module: Implement step 6, solve the straight line The intersection point with the boundary of the safety set yields the expected fatigue life.

[0080] Results Output and Visualization Module: Implements step 7, outputting fluctuation damage rate, jump buckling damage rate, jump buckling rate, and expected lifetime, and plotting the safety set boundary. Linear figures and other geometric shapes.

[0081] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. It should be noted that the following embodiments are only for further illustration of the present invention and are not intended to limit it, unless otherwise stated.

[0082] Example 1

[0083] This embodiment uses a set of stress-time history data of a rectangular thin-walled structure of a certain type of high-temperature alloy (GH188) under a thermal load with a buckling coefficient of S=1.2 and an acoustic load of 148dB as an example.

[0084] 1. Calculate the critical buckling temperature of components and the entire structure:

[0085] Taking a 450mm×210mm plate with a thickness of 1.5mm as an example, the structure is divided into a grid and discretized by adopting four-sided fixed support, and the critical buckling temperature of the thin-walled structure is found to be 24℃.

[0086] 2. Transient dynamic analysis based on combined thermo-acoustic load application:

[0087] For a structure subjected to a thermal load with a buckling coefficient of 1.2 and an acoustic load of 148 dB, finite element transient analysis was used to extract the time stress results at key points, resulting in a stress sequence of 12250 points with a time step of 0.0025 seconds. The stress range was approximately -188.18 to 59.9 MPa, as shown in the attached diagram. Figure 3 As shown.

[0088] 3. Detect jump buckling behavior:

[0089] Pick ,calculate Standard deviation MPa, with a threshold of approximately 10.3 MPa. The program detected 26 candidate jump buckling points in the time stress history results, which were then merged to obtain 26 jump bucklings, with the jump buckling times distributed between approximately 0.5 and 1.1 seconds.

[0090] 4. Detection of structural damage rate and jump buckling rate:

[0091] After removing the data points 0.05 seconds before and after each buckling jump position in the original time-stress history, the remaining data represents pure structural fluctuation data. Several cycles were obtained using the rainflow counting method, and SWT mean stress correction was applied to each cycle. ,in, This is the equivalent stress amplitude after SWT mean stress correction. This represents the maximum stress value of the cycle. For the minimum stress of this cycle, the material parameter K = 1 × e 20 , Calculate the total time. =1.229 seconds, obtained =1.512×10 -9 / Second.

[0092] Jump buckling rate: The buckling span of 26 jumps was 1.21 seconds, μ = 27.24 jumps / second.

[0093] 5. Construct the boundary line of the safe set:

[0094] Safety set boundary: take ,get =6.335×10 8 This indicates that, with a buckling coefficient S=1.2 and a sound pressure level SPL=148dB, the number of jump buckling cycles required for the structure to fail due to jump buckling is 6.335×10⁻⁶. 8 Second-rate; It is 6.66×10 7 In seconds, that is, at a buckling coefficient S=1.2 and a sound pressure level SPL=148dB, the time required for the structure to fail due to wave motion is 6.66×10⁻⁶ seconds. 7 Second.

[0095] 6. Calculate the expected failure time :

[0096] Expected life: The intersection of the safety set boundary and the jump buckling rate is: =4285629.16 seconds (1190.45 hours), indicating that the structural life of this time-stress history is mainly determined by fluctuation damage, because much smaller The expected fatigue life is within the acceptable range for engineering applications, demonstrating the effectiveness and reliability of the calculation method.

[0097] 7. Results Output and Visualization:

[0098] A cumulative damage matrix is ​​established on the time-jump buckling number plane (tM), and the evolution of the damage field over time and jump buckling events is fully presented graphically. This damage matrix clearly reflects the cumulative damage state at different time points and jump buckling numbers, providing intuitive data support for understanding the fatigue failure mechanism of structures.

[0099] Based on this, the safety set boundary curve (solid line) is plotted. This boundary is defined by the critical condition that cumulative damage equals 1, representing the maximum time the structure can withstand at a given number of jump bucklings, or equivalently, the maximum number of jump bucklings it can withstand within a given time, i.e., the safe operating limit of the structure. Simultaneously, the jump buckling cumulative straight line is plotted. (Dashed line), whose slope is determined by the jump buckling rate obtained from the previous steps, describes the average cumulative trend of jump buckling events over time during the actual service of the structure.

[0100] The intersection of the two feature lines represents the expected failure time (highlighted with a black dot if the intersection is within the coordinate axis display range). This point marks the theoretical moment when the cumulative damage to the structure reaches the critical value of 1, i.e., the predicted failure point. Finally, the output is a complete image including the safety set boundary, the jump buckling cumulative line, and the intersection point annotations, as shown in the attached diagram in the specification. Figure 4 As shown in the figure, this diagram visually illustrates the division between the "safe operating zone (D < 1)" and the "failure zone (D > 1)," clearly explaining the life prediction principle based on damage accumulation theory—that is, mapping the random jump buckling process to a deterministic cumulative path through statistical averaging, thereby providing a life estimate with engineering reference value within a probabilistic framework. Simultaneously, the program will output key parameters such as expected failure time (unit: seconds), fluctuation damage rate, jump buckling damage rate, and jump buckling rate, providing a quantitative basis for structural fatigue resistance design.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the skipped buckling fatigue life of a thin-walled structure, characterized in that, Includes the following steps: Step 1: Calculate the critical buckling temperature of the components and the entire structure; Step 2: Perform transient dynamic analysis by applying a combined thermo-acoustic load; Step 3: Detect jump buckling behavior; Step 4: Detection of structural damage rate and jump buckling rate; specifically including the following sub-steps: Step 4.1, Fluctuation Damage Rate Detection: In the original time-stress sequence, data points within a certain time window before and after each jump buckling occurrence are removed to obtain the pure wave stress sequence. ;right Peak and valley values ​​were extracted, and several stress cycles were obtained using the rainflow counting method. Each cycle had a stress range R and a mean M. The damage for each cycle was calculated using the material's SN curve and mean stress correction. The total fluctuation damage is obtained by summing all the cyclic damages. Simultaneously calculate the total time of fluctuation data. The fluctuation damage rate was obtained. ;in, It is the start time of the fluctuating load data; It is the termination time of the fluctuating load data; Step 4.2, Jump flexion injury rate Detection: For each detected jump buckling location in the time stress history, the average stress within each time window before and after the jump buckling is taken to obtain the stress level before the jump buckling. and stress level after jump buckling The stress range of this jump buckling average stress ; Calculate the damage of this jump-buckling cycle The damage is calculated for all detected jump buckling events, and the average damage for all jump buckling events is taken to obtain the single jump buckling damage. Step 4.3 Jump buckling rate Calculation: Use the program to determine the number of buckling bounces in the original time-stress history. If the number of buckling bounces... ,but That is, the number of jump bucklings divided by the total time span during which jump bucklings occur; where, The moment when the first jump buckling occurs. The time when the last jump buckling occurs; if ,but If the program detects that there is no jump in buckling time in the original time-stress history, then output... =0; Step 5: Construct the safety set boundary line, and apply the total damage formula. Construct the safety set boundary line for the cumulative damage model; set D=1 to obtain the safety set boundary line. ,in Let t be the initial injury, t be time, and M be the number of jump bucklings. For fluctuation damage rate, This represents the jump-bending injury rate; Step 6: Calculate the expected failure time and solve the linear equation. The intersection point with the safety set boundary yields the expected fatigue life, which is the expected failure time. .

2. The method for predicting the skipped buckling fatigue life of a thin-walled structure according to claim 1, characterized in that, Step 1 specifically involves: establishing a finite element model of the complex structural components and dividing the mesh; based on the structural geometric features and boundary conditions, using shell elements or solid elements for discretization modeling to ensure that the mesh density can accurately capture the thermal buckling modes and stress gradients in order to calculate the critical buckling temperature of the structure.

3. The method for predicting the skipped buckling fatigue life of a thin-walled structure according to claim 1, characterized in that, Step 2 specifically involves applying a uniform temperature field to the structure to simulate the influence of the thermal environment on the structural material properties and stress. Then, the measured noise pressure time history is applied to the surface of the structure. This sound pressure time history serves as the external normal uniform pressure load on the surface of the structure and is applied to the surface of the finite element model.

4. The method for predicting the skipped buckling fatigue life of a thin-walled structure according to claim 1, characterized in that, Step 3 specifically involves: after completing the transient dynamic analysis of the combined thermo-acoustic loading, finding the node or element where the maximum value of Von Mises stress or principal stress occurs throughout the entire time history, and deriving the time stress history of that node or element; Calculate the difference sequence of adjacent stress points in the stress history over this time period. Find its standard deviation and set a threshold ,in The empirical coefficient is 2~5; find all The location is used as the candidate time point for the jump buckling time; the time interval is less than the minimum time interval threshold. Multiple candidate points are merged into a single jump buckling, and the jump buckling moment is recorded within the program. and number of jump flexion .

5. The method for predicting the skipped buckling fatigue life of a thin-walled structure according to claim 1, characterized in that, Step 5 specifically involves: The intercept of the safety set boundary line on the vertical axis Expressed as the number of jump bucklings required for a structure to fail if it only undergoes jump buckling, the intercept on the horizontal axis. It is expressed as the time required for the structure to fail if it only experiences pure fluctuations.

6. The method for predicting the skipped buckling fatigue life of a thin-walled structure according to claim 1, characterized in that, Step 6 specifically involves: In the time-jump buckling count expectation plane, the expected increase in the number of jump bucklings follows a linear curve. The x-coordinate of the intersection point of this straight line and the safety set boundary line is the expected failure time. ;when and hour, ,like or The expected failure time is equal to the time required for the structure to fail under simple fluctuations. .

7. The method for predicting the skipped buckling fatigue life of a thin-walled structure according to claim 1, characterized in that, The method also includes step 7, result output and visualization: outputting the fluctuation damage rate. Jump flexion injury rate Jump buckling rate Expected failure time This visually demonstrates the randomness of the jump buckling process and the principles of lifetime prediction.

8. A system for predicting the random jump buckling fatigue life of a thermal buckling plate, characterized in that, This system is used to implement the prediction method according to any one of claims 1-7; the system comprises: Data acquisition module: Acquires stress time history data of the structure under combined thermo-acoustic loads; Critical buckling temperature calculation module: Implements step 1, calculates the critical buckling temperature of a component or the whole structure using the finite element method, and determines the temperature threshold at which the structure will buckle. Thermo-acoustic joint loading and transient analysis module: Implements step 2, applies a uniform temperature field and Gaussian white noise sound pressure time history to the structure, performs transient dynamic analysis, and obtains the dynamic response of the structure; Jump buckling detection module: Implements step 3, automatically identifies jump buckling events from stress time history, and records the jump buckling time and the number of jump bucklings; Damage rate and jump buckling rate detection module: Implements step 4 and includes three sub-modules: The fluctuation damage rate calculation submodule performs rainflow counting and damage accumulation on pure fluctuation stress and calculates the fluctuation damage per unit time. Jump buckling injury rate calculation submodule: Constructs large-scale stress cycles for each jump buckling event and calculates the average injury of a single jump buckling; Jump buckling rate calculation submodule: Calculates the average rate at which jump buckling occurs based on the number of jump bucklings and the time span; Safety set boundary construction module: Implements step 5, based on the total damage formula. Construct the safety set boundary line for the cumulative damage model; Expected failure time calculation module: Implement step 6, solve the straight line The intersection point with the boundary of the safety set yields the expected fatigue life.

9. The thermal buckling plate random jump buckling fatigue life prediction system according to claim 8, characterized in that, The system also includes a results output and visualization module: implementing step 7, outputting fluctuation damage rate, jump buckling damage rate, jump buckling rate, and expected lifetime, and plotting the safety set boundary, straight line.

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