A method, system, device and medium for analyzing the rotary system life of an electric drive system considering thermal expansion

Abstract

The present application belongs to the technical field of new energy automobile electric drive system reliability design, and particularly relates to a rotating system life analysis method, system, equipment and medium of electric drive system considering thermal expansion, an electric drive bridge simulation model is constructed, and initial life checking is performed. Based on the spectrum statistical load distribution, the damage equivalent principle is adopted to compress it into a periodic bench load spectrum, and the damage equivalence is verified through simulation. Based on the bench spectrum, a thermal balance test is performed to obtain the steady-state temperature field of each component. The temperature field and the bench spectrum are used as inputs to perform thermal-mechanical coupling simulation, and the final life value considering thermal effect is calculated and output after comparison and verification with the initial result. The method shortens the simulation time through damage equivalent compression, obtains the real temperature boundary through bench thermal test, and accurately quantifies the influence of thermal expansion through thermal-mechanical coupling simulation, thereby improving the accuracy of life prediction of the rotating system under high thermal working conditions on the premise of ensuring efficiency.

Description

Technical Field

[0001] This invention belongs to the field of reliability design technology for electric drive systems of new energy vehicles, and specifically relates to a method, system, equipment and medium for analyzing the life of rotating parts of an electric drive system that takes thermal expansion into account. Background Technology

[0002] With the rapid development of new energy vehicles, the electric drive system, as a major component, directly affects the safety and operating costs of the entire vehicle due to its reliability and lifespan. Rotating systems (such as bearings and gears), as key components subjected to dynamic loads in electric drive systems, are constantly exposed to complex variable loads and temperature changes. Their failure modes mainly include fatigue, wear, and pitting.

[0003] When performing life analysis, the relevant technologies use a proportional reduction method for load spectrum compression. Due to the differences in fatigue damage characteristics of bearings, gears, and shafts, adjusting the compression of each segment of the load spectrum will result in a large deviation between the damage effect of the compressed bench load spectrum on different components and the actual vehicle load spectrum. This makes it impossible to truly replicate the durability test of the rotating system by the actual vehicle, and the subsequent test and simulation results lose their reference value.

[0004] For rotating system life verification, life assessment is based on simulation of mechanical loads. However, in reality, the operation of an electric drive axle involves heat generated by gear meshing and bearing friction, which affects the components. Especially under actual operating conditions, increased temperature alters key parameters such as the coefficient of thermal expansion and modulus of elasticity of materials, inducing additional thermal stress and reducing the material's fatigue limit. This leads to a significant deviation between the life assessment results under mechanical loads and the actual operating life. In related multi-field coupling analysis, a uniform temperature distribution is used for the temperature field. This approach fails to accurately reflect the actual temperature distribution differences in the gear meshing area, bearing housing, and lubrication oil cavity of the electric drive axle, resulting in distorted thermal stress calculations and consequently affecting the accuracy of life assessment under multi-field coupling. Summary of the Invention

[0005] This invention provides a method for analyzing the life of rotating systems in an electric drive system considering thermal expansion. The method performs equivalent compression of the actual vehicle load spectrum based on the Palmgren-Miner linear fatigue damage theory, ensuring that the calculated results of the compressed bench load spectrum of the rotating system are consistent with those of the actual vehicle load spectrum. Furthermore, a thermal balance test is conducted based on the equivalent load spectrum, measuring the temperature at various axle components. These temperature values ​​are input as reference factors into the simulation software, thereby achieving reliable life verification of the rotating system under multi-field coupling.

[0006] The methods include: S1: Construct a model of the electric drive axle system including the housing, shaft, and hub, and perform finite element mesh generation and condensation processing; S2: Input the torque, speed and gear information extracted from the actual vehicle load spectrum after signal processing into the electric drive axle system model of S1; Based on the material SN curve and ISO16281 standard, combined with the system deformation and load characteristics, calculate the first total damage value of the rotating system under the actual vehicle load spectrum. S3: Based on the actual vehicle load spectrum used in S2, drive and energy recovery conditions are distinguished by gear, and torque and speed are separated by gear; using the rotational counting method and Markov matrix, the frequency of occurrence of each torque-speed combination is counted to form a load distribution matrix; S4: Based on the load distribution matrix, the second total damage value of the rotating system is calculated using the Palmgren-Miner linear damage theory; the torque is segmented according to the preset number of segments, and the load spectrum of the test bench is generated by increasing the amplitude of each segment and adjusting the number of cycles, so that the error between the second total damage value and the first total damage value does not exceed the preset threshold. S5: Input the bench load spectrum generated in S4 into the electric drive bridge system model in S1 to obtain the third total damage value based on the rotating system; if the deviation between the third total damage value and the first total damage value exceeds the allowable range, return to S4 to adjust the number of segments or the number of cycles until the equivalence requirement is met. S6: Using the equivalent bench load spectrum verified by S5 as the test condition, conduct the electric drive bridge thermal balance test in a windless natural convection environment; after completing a break-in period of no less than the preset time, arrange thermocouples around the rotating system and the shell, and record the steady-state temperature data when thermal equilibrium is reached under each working condition. S7: The steady-state temperature data measured in S6 is used as the temperature field boundary condition, mapped to the corresponding node of the electric drive bridge system model in S1, and applied together with the bench load spectrum in S4. A thermo-mechanical multi-field coupled simulation is performed to calculate the total damage value of the rotating system considering the thermal expansion effect. S8: Compare the total damage value of the rotating system with the first total damage value; if the difference between the two is within the preset allowable range, the total damage value of the rotating system will be output as the final life assessment conclusion.

[0007] It should be further explained that S2 specifically includes the following steps: S21: Convert the torque, speed and gear information of each time step in the actual vehicle load spectrum into a load input sequence that can be recognized by MASTA, align the model dynamics solution step size according to the sampling frequency, and insert a transition segment at each gear switching point; S22: In MASTA, call the material SN curve database, specify the corresponding damage slope for the shaft and gear, and call the ISO16281 standard module for bearing life calculation, inputting the actual bearing model, internal geometric parameters and contact load path; S23: Extract the time-varying stress history of each key position of the rotating system, count the bearing raceway, gear tooth root, and shaft shoulder transition area respectively, and accumulate them segment by segment according to the Palmgren-Miner formula based on their respective damage slopes to obtain the first total damage value of the rotating system under the actual vehicle load spectrum.

[0008] It should be further explained that S3 specifically includes the following steps: S31: Separate the actual vehicle load spectrum into several subsequences according to gear position, and further divide each subsequence into positive motor output torque and negative motor output torque to form a time torque speed dataset; S32: Using the rotational speed as the reference axis, the torque signal is resampled for each revolution to eliminate the non-periodicity caused by speed change; then, peak-valley extraction is applied to the resampled torque mileage to identify stress cycles and record the amplitude, mean and corresponding speed range of each cycle. S33: Construct a two-dimensional Markov state transition matrix. The state is defined as a preset torque-speed discrete interval. Statistically count the frequency of state transitions between adjacent sampling points to obtain the transition probability matrix. Accumulate the dwell time of each state to form a load distribution matrix.

[0009] It should be further explained that S4 specifically includes the following steps: S41. Based on the load distribution matrix, divide the torque interval into preset segments, determine the torque reference value of each sub-interval, and extract the load cycle information within it. S42. For each torque sub-interval, adjust the torque amplitude according to its load cycle information and calculate the number of cycles so that the error between the adjusted total damage value and the first total damage value meets the requirements. S43. Based on the adjusted torque amplitude and number of cycles, generate a bench load spectrum and verify its equivalence by comparing the total damage value. If it does not meet the requirements, return to the adjustment parameters.

[0010] It should be further explained that S5 specifically includes the following steps: S51. Organize the test load spectrum into a load sequence that can be recognized by MASTA, and configure simulation parameters for each operating point. S52. Perform transient simulation in MASTA, extract the stress time history of key components, and perform cycle counting to obtain stress cycle data for each working point. S53. Based on the damage slope of each component, accumulate the damage value of stress cycle at each working point to obtain the third total damage value.

[0011] It should be further explained that S7 specifically includes the following steps: S71. Based on the location of the measuring points in the thermal equilibrium test, establish the mapping relationship and weight coefficients between them and the nodes of the finite element model; S72. Based on this mapping relationship, the steady-state temperature values ​​of the measuring points are assigned to the model nodes to generate the temperature field distribution corresponding to each working condition of the test load spectrum, and it is defined as the thermal boundary condition for simulation. S73. Activate the temperature dependence of the material's thermal performance parameters in the software, apply the temperature field and load spectrum together, obtain the thermomechanical stress through coupling solution, and then calculate the total damage value of the rotating system.

[0012] It should be further noted that S4 also refers to all load cycles within a certain torque segment of the actual vehicle load spectrum, denoted as cycles 1 to k, corresponding to cycle numbers n1, n2...n. k Torque T1, T2…T k By combining the damage slope p of the corresponding component in the rotating system with the formula of the equal damage principle, the equivalent torque of this segment can be calculated. : .

[0013] The present invention also provides a system for analyzing the life of a rotating system in an electric drive system, taking into account thermal expansion. The system includes: The modeling module is used to construct a model of the electric drive axle system, including the housing, shaft, and hub, and to perform finite element mesh generation and condensation processing. The rotating system damage calculation module is used to input the torque, speed and gear information extracted from the actual vehicle load spectrum after signal processing into the electric drive axle system model; based on the material SN curve and ISO16281 standard, combined with the system deformation and load characteristics, it calculates the first total damage value of the rotating system under the actual vehicle load spectrum. The load distribution matrix generation module uses the actual vehicle load spectrum, which distinguishes between driving and energy recovery conditions according to gear, and separates torque and speed by gear; it uses the rotational counting method and Markov matrix to count the frequency of occurrence of each torque-speed combination to form the load distribution matrix; The bench load spectrum generation module calculates the second total damage value of the rotating system based on the load distribution matrix and the Palmgren-Miner linear damage theory. The torque is segmented according to a preset number of segments. By increasing the amplitude of each segment and adjusting the number of cycles, the bench load spectrum is generated so that the error between the second total damage value and the first total damage value does not exceed a preset threshold. The bench load spectrum equivalence verification module is used to input the generated bench load spectrum into the electric drive bridge system model to obtain the third total damage value based on the rotating system; if the deviation between the third total damage value and the first total damage value exceeds the allowable range, it returns to adjust the number of segments or the number of cycles until the equivalence requirements are met. The electric drive bridge thermal balance test module is used to conduct electric drive bridge thermal balance tests under windless natural convection environment with a verified equivalent bench load spectrum as the test conditions. After a break-in period of no less than the preset time, thermocouples are arranged around the rotating system and the shell to record the steady-state temperature data when thermal balance is reached under each working condition. The coupled simulation module is used to map the measured steady-state temperature data as the temperature field boundary condition to the corresponding node of the electric drive bridge system model, and apply it together with the bench load spectrum to perform thermo-mechanical multi-field coupled simulation and calculate the total damage value of the rotating system considering the thermal expansion effect. The life assessment conclusion output module is used to compare the total damage value of the rotating system with the first total damage value; if the difference between the two is within the preset allowable range, the total damage value of the rotating system is output as the final life assessment conclusion.

[0014] According to another embodiment of this application, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method for analyzing the life of the rotating system of an electric drive system taking thermal expansion into account.

[0015] According to another embodiment of this application, a storage medium is also provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the method for analyzing the life of the rotating system of an electric drive system considering thermal expansion.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: The electric drive axle simulation model constructed using the rotating system life analysis method considering thermal expansion provided by this invention, through finite element mesh generation and condensation processing, and setting component coupling relationships, can reproduce the actual mechanical structure and motion characteristics of the electric drive axle, reducing calculation distortion caused by model simplification or parameter deviation. Based on the principle of equal damage and Palmgren-Miner linear damage theory, the load spectrum compression method transforms dispersed random loads from the actual vehicle into periodic bench loads while ensuring equivalent cumulative damage to the rotating system, thus reducing the bench test cycle and simulation calculation time.

[0017] This invention combines thermal balance testing with multi-field coupled simulation. By measuring the steady-state temperature of each component under a bench load spectrum, it provides realistic temperature boundary conditions for the simulation. This allows life verification to move beyond purely mechanical loads and incorporate the effects of additional thermal stress caused by thermal expansion, making the life assessment more closely reflect the actual operating conditions of the electric drive axle. The invention's dual life verification and stratified verification method, by comparing life results under purely mechanical loads and thermo-mechanical coupled loads, identifies the degree of influence of the temperature field on the rotating system's life, eliminating errors in load spectrum compression and simulation parameter settings, ensuring the reliability of the final life assessment conclusion. Damage equivalence control between the bench load spectrum and the actual vehicle load spectrum enables the bench test to accurately replicate the damage effects of the actual vehicle on the rotating system, achieving the goal of replacing long-term actual vehicle road testing with bench testing. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Flowchart of a method for analyzing the lifespan of rotating parts in an electric drive system, taking thermal expansion into account; Figure 2 Flowchart of an embodiment of a method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion; Figure 3 Example diagram of electric drive bridge assembly model; Figure 4 This is an example diagram for analyzing the load spectrum data of a real vehicle. Figure 5 A bar chart for analyzing bench load spectrum data; Figure 6 This is an example diagram showing the temperature test results at a certain measuring point on the electric drive bridge. Figure 7 This is a schematic diagram of an electronic device. Detailed Implementation

[0020] like Figure 1As shown, the purpose of this invention is to provide a method for analyzing the rotating system life of an electric drive system considering thermal expansion. A system-level electric drive axle model is established using MASTA. Based on the principle of equivalent damage, the actual vehicle load spectrum is compressed into a bench load spectrum. The rotating system life under the two load spectra is compared and calculated using the constructed MASTA electric drive axle model, ensuring the accuracy of the load spectrum compression. This achieves the compression of a large amount of real-vehicle load spectrum that changes over time into a few corresponding equivalent operating points. The compressed bench load spectrum is then used for electric drive axle thermal balance tests, measuring the temperature at the points of interest. The test data is imported into MASTA software, and the rotating system life is re-verified based on the bench load spectrum, thereby achieving rapid and reliable verification of the rotating system life under multi-field coupling of temperature and stress fields.

[0021] The following describes in detail the method for analyzing the rotating system life of an electrically driven system considering thermal expansion, as per this application. Specific details, such as particular system structures and techniques, are presented for illustrative purposes and not for limitation, to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0022] It should be understood that, when used in this specification, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0023] The terms "one embodiment" or "some embodiments" used in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this application do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0024] The technical solutions of the embodiments of the present invention 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figure 2The diagram shows a flowchart of a method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion, as per a specific embodiment. The method includes: S1: Construct a model of the electric drive axle system including the housing, shaft, and hub, and perform finite element mesh generation and condensation processing.

[0026] In some embodiments, a parametric multibody dynamics model including the axle housing, main reduction housing, differential housing, and rotating system is established in MASTA. Irregular structures such as housings, irregular shafts, and spokes are meshed using tetrahedral elements, with element sizes adaptively controlled based on geometric curvature and stress gradient. Key regions, such as the shoulder transition area, are represented by elements with specific side lengths.

[0027] After meshing, the model is exported to NASTRAN format and imported into MASTA for modal reduction, preserving all physical interface degrees of freedom. REB3 coupling is used between the hub and bearing, RBE3 is used for spline connections, and hub constraints are applied and grounded at the axle housing leaf spring seat. This modeling method preserves the influence of the flexible housing on gear meshing misalignment and avoids contact load distortion caused by rigid assumptions.

[0028] As can be seen, parametric condensation simplifies the model by retaining key degrees of freedom, uses RBE3 coupling to simulate the force transmission characteristics of rigid connections, and uses grounding constraints to restore the actual vehicle installation state of the axle housing, thus constructing a system model consistent with the mechanical characteristics of the physical prototype.

[0029] S2: Input the torque, speed and gear information extracted from the actual vehicle load spectrum after signal processing into the electric drive axle system model of S1; Based on the material SN curve and ISO16281 standard, combined with the system deformation and load characteristics, calculate the first total damage value of the rotating system under the actual vehicle load spectrum.

[0030] In some embodiments, loads are applied according to gear position to recreate the force scenarios under different driving conditions, and the implicit solver adapts to the dynamic analysis of load changes.

[0031] In this embodiment, the composite material SN curve and damage calculation using ISO standards can be used to assess fatigue life and ensure the engineering applicability of the results. This provides a baseline damage value under actual vehicle load spectrum, offering a basis for verifying the validity of bench load spectrum and checking multi-field coupled life, ensuring that the damage value closely approximates the actual fatigue condition of a real vehicle.

[0032] S2 specifically includes the following steps: S21: Convert the torque, speed and gear information of each time step in the actual vehicle load spectrum into a load input sequence that can be recognized by MASTA, align the model dynamics solution step size according to the sampling frequency, and insert a transition segment at each gear switching point to avoid step shock.

[0033] S22: In MASTA, call the material SN curve database, specify the corresponding damage slope for the shaft and gear, and call the ISO16281 standard module for bearing life calculation, inputting the actual bearing model, internal geometric parameters and contact load path.

[0034] Alternatively, the material's SN curve is stored in the MASTA material library, including fatigue limit, strength coefficient, and fatigue strength index. The effective fatigue strength is set based on the depth of the hardened layer on the carburized gear surface. The bearing module, according to ISO 16281, requires input of parameters such as the number of rolling elements, contact angle, and raceway curvature ratio, which MASTA then automatically calculates and corrects for the rated life. This approach integrates components with different failure mechanisms into a unified damage framework, avoiding overestimation or underestimation of life due to the use of a single slope.

[0035] S23: Extract the time-varying stress history of each key position of the rotating system, count the bearing raceway, gear tooth root, and shaft shoulder transition area respectively, and accumulate them segment by segment according to the Palmgren-Miner formula based on their respective damage slopes to obtain the first total damage value of the rotating system under the actual vehicle load spectrum.

[0036] This embodiment extracts peak and valley values ​​from the stress time history, constructs a hysteresis loop, and statistically analyzes the amplitude and mean of each complete cycle. For gear teeth roots, the bending stress amplitude is considered; for bearing raceways, the Hertzian contact stress amplitude is considered; and for shaft shoulders, equivalent stress is extracted. The first total damage value is the largest among all components, and the lifespan of the most critical component is used as the control factor. In this way, all damage information except for load sequence effects is preserved, achieving a balance between engineering accuracy and computational efficiency.

[0037] S3: Based on the actual vehicle load spectrum used in S2, drive and energy recovery conditions are distinguished by gear, and torque and speed are separated by gear; using the rotational counting method and Markov matrix, the frequency of occurrence of each torque-speed combination is counted to form a load distribution matrix.

[0038] Alternatively, S3 specifically includes the following steps: S31: Separate the actual vehicle load spectrum into several subsequences according to gear position, and further divide each subsequence into positive motor output torque and negative motor output torque to form a time-torque-speed dataset.

[0039] S32: Using the rotational speed as the reference axis, the torque signal is resampled for each revolution to eliminate the non-periodicity caused by speed change; then, peak-valley extraction is applied to the resampled torque mileage to identify stress cycles and record the amplitude, mean and corresponding speed range of each cycle.

[0040] S33: Construct a two-dimensional Markov state transition matrix. The state is defined as a preset torque-speed discrete interval. Statistically count the frequency of state transitions between adjacent sampling points to obtain the transition probability matrix. Accumulate the dwell time of each state to form a load distribution matrix.

[0041] In some embodiments, the gear intervals are divided according to the speed range of each gear of the electric drive axle. Load cycles are extracted, and the peak value, valley value, and speed of each cycle are recorded. Optionally, multiple torque intervals are divided according to the maximum torque, a Markov transition probability matrix is ​​constructed, and the number of interval transitions between adjacent cycles is counted to form a load distribution matrix.

[0042] Optionally, the Markov matrix can be divided into equal-width segments. Rotational speeds are segmented according to commonly used operating ranges. If two adjacent sampling points fall into state A and state B respectively, the counter C(A→B) is incremented by 1. The final load distribution matrix involves the frequency of state dwell times, reflecting the number of occurrences of a certain torque-speed combination, and also involves the transition frequency, reflecting the severity of operating condition switching. In this way, the Markov matrix retains load path information, allowing for the reproduction of the dynamic characteristics of real-world operating conditions when generating the bench load spectrum.

[0043] S4: Based on the load distribution matrix, the second total damage value of the rotating system is calculated using the Palmgren-Miner linear damage theory; the torque is segmented according to the preset number of segments, and the load spectrum of the test bench is generated by increasing the amplitude of each segment and adjusting the number of cycles, so that the error between the second total damage value and the first total damage value does not exceed the preset threshold.

[0044] In some embodiments, compressing the load according to the principle of equal damage can replace the dispersed load with concentrated operating points while ensuring that the total damage is equivalent. The temporal arrangement of the Markov matrix restores the variation logic of the actual vehicle load. By reducing the thousands of operating points of the original actual vehicle load spectrum, the bench test time is shortened.

[0045] S5: Input the bench load spectrum generated in S4 into the electric drive bridge system model in S1 to obtain the third total damage value based on the rotating system; if the deviation between the third total damage value and the first total damage value exceeds the allowable range, return to S4 to adjust the number of segments or the number of cycles until the equivalence requirement is met.

[0046] In some embodiments, the bench load spectrum is converted into a MASTA file, and based on the constraint settings of S1, torque and speed are applied to the corresponding shaft end according to the gear.

[0047] Set the solver parameters to be consistent with S2, execute the simulation, extract the stress of key parts, and calculate the third total damage value according to the same standard. Compare the third total damage value with the first total damage value. If the bearing damage error is greater than the preset bearing error or the system total damage error is greater than the preset total damage error, return to S4 to increase the number of segments n or adjust the number of iterations until the target is met.

[0048] S6: Using the equivalent bench load spectrum verified by S5 as the test condition, conduct the electric drive bridge thermal balance test in a windless natural convection environment; after completing a break-in period of no less than the preset time, arrange thermocouples around the rotating system and the shell, and record the steady-state temperature data when thermal equilibrium is reached under each working condition.

[0049] In some embodiments, the test is conducted in a windless environment chamber, initially with a break-in period of 36 hours at 75 Nm torque and 7000 rpm. K-type thermocouples are placed on the gear meshing area housing surface, bearing outer ring mounting seat, and lubricating oil cavity, and a vortex flow meter is used to measure flow rate. Loading is performed sequentially according to the bench load spectrum, with each condition running for 10 minutes and the oil temperature change ≤2℃. The temperature at each measuring point is recorded. If the oil temperature rises to 120℃, the condition is immediately stopped to prevent component overheating. This break-in process eliminates machining burrs and assembly stresses on the electric drive bridge, ensuring that the test data reflects the thermal characteristics under stable operating conditions. The thermal balance judgment criterion is based on the heat transfer law of the electric drive bridge, guaranteeing that the recorded temperature is the steady-state operating temperature.

[0050] S7: The steady-state temperature data measured in S6 is used as the temperature field boundary condition, mapped to the corresponding node of the electric drive bridge system model in S1, and applied together with the bench load spectrum in S4 to perform thermo-mechanical multi-field coupled simulation and calculate the total damage value of the rotating system considering the thermal expansion effect.

[0051] In some embodiments, the temperature field is solved, and then the thermal stress generated by thermal expansion is calculated. This thermal stress is then superimposed with the mechanical stress to obtain the total stress under actual working conditions. Temperature correction is applied to material parameters because temperature changes the fatigue characteristics of materials, directly affecting the damage calculation results.

[0052] S8: Compare the total damage value of the rotating system with the first total damage value; if the difference between the two is within the preset allowable range, the total damage value of the rotating system will be output as the final life assessment conclusion.

[0053] In some embodiments, the total damage value of the rotating system is compared with the first total damage value by a preset threshold, wherein the bearing damage difference is ≤5% and the total system damage difference is ≤7%.

[0054] If the difference exceeds the limit, return to S7 to check the temperature mapping or material parameter correction, and re-execute the coupled simulation; if the difference meets the limit, convert the total damage value of the rotating system into life, where life = target durability mileage / total damage value, and output the final life assessment conclusion.

[0055] It can be seen that the final lifespan conclusion considering the thermal expansion effect provides an authoritative basis for the design optimization and durability verification of the electric drive axle rotary system, and avoids the risk of product failure caused by the distortion of lifespan assessment.

[0056] In one embodiment of the present invention, based on step S4, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S4 specifically includes the following steps: S41. In the load distribution matrix obtained by the rotation counting method, the torque range is divided into equally spaced sub-ranges according to the preset number of segments n, and the torque reference value of each sub-range is determined; all load cycles in each torque sub-range are extracted, the sum of the number of cycles in the sub-range is calculated, and the average torque and speed value of each cycle are recorded.

[0057] Optionally, dividing the torque interval into preset segments (n) is to control the number of operating points in the frame test. n=6 is a common choice, which can reduce the test time and cover the main load range. When determining the torque reference value, it is necessary to ensure that the width of each sub-interval is consistent. For example, the maximum torque of 300 Nm is divided into 6 segments, each segment being 50 Nm. After this division, the load characteristics of each sub-interval are relatively uniform.

[0058] S42. For each torque sub-interval, select the maximum value of the average torque within the sub-interval as the torque amplitude of the sub-interval. If the average value is greater than or equal to the torque reference value, the amplitude is the larger of the torque reference value and the average value. If the average value is less than the torque reference value, the amplitude is the sum of the torque reference value and the average value, so that the torque amplitude of each sub-interval is not lower than the torque reference value, thus forming the adjusted torque-speed combination. Based on the Palmgren-Miner theory, the number of cycles for each combination after adjustment is calculated so that the relative error between the second total damage value and the first total damage value does not exceed a preset threshold.

[0059] S43. Sort the adjusted torque-speed combination according to the number of torque segments n to generate a bench load spectrum containing n operating points; for each operating point, set its cycle number to the sum of the cycle numbers of the sub-intervals divided by the number of operating points to ensure the damage equivalence of the bench load spectrum. The total damage value of the bench load spectrum is compared with that of the actual vehicle load spectrum. If the error exceeds the threshold, the torque reference value or sub-interval division method is adjusted until the error requirement is met.

[0060] Optionally, for all load cycles within a certain torque segment of the actual vehicle load spectrum, they are denoted as the 1st to kth cycles, corresponding to cycle numbers n1, n2...n. k Torque T1, T2…T k By combining the damage slope p of the corresponding component in the rotating system with the formula of the equal damage principle, the equivalent torque of this segment can be calculated. : .

[0061] It should be noted that sorting the adjusted torque-speed combinations by the number of segments, n, is to match the working point distribution of the test load spectrum with the damage distribution of the original load spectrum. For example, the working point amplitude is larger and the number of cycles is more in the high-damage range, while the opposite is true for the low-damage range. Setting the number of cycles for each working point to the sum of the number of cycles in the sub-ranges divided by the number of working points ensures that the total number of cycles remains unchanged, thus making the second total damage value equal to the first total damage value.

[0062] The purpose of comparing the total damage values ​​is to verify equivalence. If the error exceeds the threshold, it indicates that the torque reference value or sub-interval division is unreasonable and needs to be adjusted. Through iterative adjustments, the damage distribution of the bench load spectrum is made as close as possible to the original load spectrum to ensure the accuracy of subsequent tests and simulations.

[0063] In one embodiment of the present invention, based on step S5, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S5 specifically includes the following steps: S51: Organize the generated bench load spectrum into a block load sequence that can be recognized by MASTA according to the order of the operating points. Each operating point includes constant torque, constant speed, rotation direction and number of cycles. Set the solver time step to match the number of cycles.

[0064] S52: Based on multibody dynamics transient solution in MASTA, analyze the steady-state response of each operating point and extract the time history of bearing raceway contact stress, gear tooth root bending stress, and shaft shoulder stress; perform counting on the key positions of each component to obtain the stress cycle amplitude and mean at each operating point.

[0065] In this embodiment, since the test bench load spectrum is a combination of steady-state operating conditions, the steady-state stress response can be obtained by running one complete mechanical cycle at each operating point. MASTA locks the load and rotational speed under this operating condition during the solution process and outputs the stress time series of key nodes.

[0066] For example, the gear tooth root node outputs the bending stress waveform within each meshing cycle, containing a main peak; the bearing inner ring node outputs the Hertzian contact stress pulse sequence when the rolling element passes through. This ensures that stress characteristics equivalent to those in the actual vehicle can be extracted from the bench spectra.

[0067] S53: For each component, call its corresponding damage slope, substitute the stress cycle at each working point into the Palmgren-Miner formula and accumulate them one by one to calculate the total damage value of each component in the rotating system, and take the maximum value as the third total damage value for output.

[0068] In one embodiment of the present invention, based on step S7, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S7 specifically includes the following steps: S71. In the finite element model of MASTA software, based on the location description and three-dimensional coordinates of the thermal balance test measurement points in S6, find the nearest mesh nodes on the surface of the shell and rotating system components to form a list of corresponding measurement point nodes.

[0069] For example, a thermocouple is welded to the surface of the gear meshing area housing. This corresponds to one or more finite element nodes in the model to assign temperature values. Finding the nearest neighbor node is crucial because the experimental measurement point and the mesh node position cannot perfectly coincide; selecting the nearest node ensures minimal temperature data positioning error. For rotating components, the thermocouple is actually attached to a fixed position on the rotating shaft, but the shaft rotates in the simulation. Therefore, multiple annular nodes on the same cross-section are needed to reflect the circumferential temperature at that position; otherwise, using only one node would miss the circumferential temperature difference. The inverse square weighting is used because temperature attenuates as it propagates through space; nodes closer to the measurement point are more affected, while farther nodes are less affected. Using the inverse square weighting allows the interpolated temperature field to more closely approximate the actual spatial distribution.

[0070] For the measuring points located on the rotating component, multiple annular nodes on the same cross section are selected as mapping objects according to their circumferential angle and axial position, and a weight coefficient is configured for each node.

[0071] S72. Distribute the steady-state temperature values ​​of each working condition recorded in S6 to the model nodes according to the mapping relationship and weight coefficients in S71. Perform circumferential temperature interpolation on the nodes of the rotating component section to form a continuous temperature field distribution. In the model boundary condition settings, the temperature field is defined as the initial condition corresponding one-to-one with each working condition segment of the S4 bench load spectrum, and a time-varying temperature field is generated by linear interpolation in the torque change transition segment.

[0072] It should be noted that after assigning temperature values ​​to nodes according to weights, circumferential interpolation is required for the cross-section of the rotating component. This is because the experiment can only measure temperature in one direction, while the actual operating temperature of that cross-section will vary slightly in different directions due to cooling conditions or the location of the heat source. Interpolation can infer the temperature of the entire toroidal surface. The temperature field is mapped to the load spectrum conditions of the test bench because each torque condition has a stable temperature state during the experiment. The simulation must be initialized with the corresponding temperature under the same conditions so that the coupling of heat and force occurs under realistic conditions. The torque transition section uses linear interpolation to generate a time-varying temperature field because the temperature does not jump instantaneously when shifting gears or changing torque during the experiment. Linear transition can simulate the effect of thermal inertia, allowing the temperature to smoothly follow load changes without introducing unreasonable thermal shocks into the calculation.

[0073] S73. In the MASTA multi-field coupling analysis module, enable the temperature dependence table of the material's thermal expansion coefficient and elastic modulus, set up heat conduction and heat convection calculations, and apply the time-varying temperature field generated in S72 together with the bench load spectrum in S4. During the solution process, first calculate the temperature distribution at each time step, then calculate the thermal strain and superimpose it on the mechanical strain to obtain the total strain and stress. Based on the Palmgren-Miner theory, accumulate the damage of each component of the rotating system to obtain the total damage value of the rotating system considering the thermal expansion effect.

[0074] Considering that heat conduction and convection calculations allow the model to automatically estimate temperatures at unmeasured locations, such as inside oil chambers or on the back of bearing housings—areas without thermocouples where heat will still transfer from high-temperature to low-temperature regions—a complete temperature field cannot be obtained without considering conduction and convection. Temperature is calculated before thermal strain because thermal strain is determined by temperature distribution; only by knowing the temperature of each node can its expansion or contraction be calculated. The total strain is obtained by superimposing thermal and mechanical strains, allowing for the determination of the true stress distribution.

[0075] For example, gear expansion at high temperatures alters the meshing clearance, increasing contact stress. By performing Palmgern-Miner damage accumulation using the superimposed stress, the additional thermal stress caused by thermal expansion is factored into the fatigue life, resulting in a total damage value that reflects the true lifespan under the combined effects of thermodynamics. This multi-field coupled simulation no longer simply calculates lifespan using cold-state stress but fully incorporates the experimentally measured thermal state, making the results closer to actual test bench operation.

[0076] Furthermore, as a more specific embodiment of the above-mentioned method for rapid and accurate analysis of the lifespan of the rotating system of an electric drive system, in order to fully illustrate the specific implementation process of this embodiment, the following further method is provided, which includes: S501: Establish a parametric model of the gear and shaft system in MASTA, mainly including rotating parts such as bearings, gears, and shafts, as well as components such as the axle housing, main reduction gear housing, and differential. Tetrahedral meshes are created for key components such as the housing, shaft, and spokes. The full finite element model is imported into MASTA for condensation. The rotating parts are selected from the bearing library based on the actual bearing type. REB3 coupling is used between the spokes and the bearings. RBE3 coupling is used for the shaft, rotating parts, and spline connections.

[0077] A hub connection is established at the axle housing leaf spring seat location, and the axle housing is grounded to ensure the accuracy of the system model. The MASTA simulation model of the electric drive axle is as follows: Figure 3 As shown, an acceleration sensor is installed around the oil drain hole in the axle housing to measure the dynamic response of the system.

[0078] S502: High-precision onboard sensors collect real-world road load spectra. The raw signals are processed to obtain gear, torque, and speed information for that road segment. The collected real-world data is then proportionally scaled up according to the required mileage (e.g., 1 million kilometers). Figure 4 As shown, the actual vehicle load spectrum is input into the MASTA software, and the life of the electric drive axle rotary system is checked based on the actual vehicle load spectrum.

[0079] S503: Based on the actual vehicle load spectrum, fully considering drive and energy recovery, torque and speed are segmented according to the number of gears. Based on the Palmgren-Miner linear damage theory, corresponding damage slopes are selected for different rotating parts to calculate the corresponding damage values. Without inducing plastic deformation, torque is processed in segments to increase torque and speed at each operating point, thereby reducing the load spectrum duration. By adjusting the number of cycles, the number of torque segment intervals in this example is ensured to be n=6, with 6 operating points for both forward and reverse drives. Figure 5 As shown.

[0080] In this embodiment, the bearing band matching damage slope is taken as 3.0. The gear damage is related to the material's heat treatment process: carburizing is taken as 6, and the shaft as 5. The damage principle is as follows:

[0081] Where p is the damage slope, T is the torque, and n is the number of cycles.

[0082] S504: By adjusting the number of cycles, it is ensured that the same load spectrum can simultaneously satisfy the damage equivalence of different components of the rotating system. The error of the total damage value corresponding to the bench load spectrum and the actual vehicle load spectrum of different components does not exceed 20%. The original large number of working condition points that change with time are output as batch working condition statistical points. The damage value comparison error is shown in Table 1.

[0083] Table 1: Error Table for Damage Value Comparison

[0084] S505: The life of the rotating system is checked based on the test load spectrum and the original load. The check results are shown in Tables 2 and 3. The results for a certain bearing and gear in the rotating system are basically consistent with the calculation results of the actual vehicle load spectrum and the test load spectrum, with a maximum error of no more than 2.5%.

[0085] Table 2: Verification Results of Rotary Gear Systems

[0086] Table 3: Verification Results of Rotary System Bearings

[0087] S506: If the actual vehicle load spectrum differs significantly from the original load spectrum, the number of torque segments n is appropriately increased. Based on the principle of equivalent damage, the actual vehicle load spectrum is compressed into a bench load spectrum. Comparing the two for the difference in the life of the rotating system, the safety factor is generally no more than 10%, and it can be considered that the bench load spectrum is not distorted.

[0088] S507: The electric drive axle thermal balance test was conducted under bench load as the test condition in a windless environment with natural air convection. Prior to the formal test, a break-in period of no less than 36 hours was performed, with the motor output torque at 75 Nm and the speed at 7000 rpm during the break-in period. During the test, the lubricating oil temperature at each measuring point was recorded using a K-type thermocouple sensor, and the flow rate was measured using a turbine flow meter. Temperature and flow signals were acquired and stored using an NI data acquisition card until the end of the test.

[0089] S508: The temperatures at each measuring point under the load spectrum conditions obtained from the thermal balance test of the electric drive bridge are compiled, such as... Figure 6 As shown, the temperature change at a measuring point of the rotating system under the condition of 93.4 Nm is displayed. The corresponding test data under the condition is used as input into MASTA, and the life of the rotating system is re-verified based on the temperature field and stress field. The verification results are shown in Tables 4 and 5.

[0090] Table 4: Gear Verification Results

[0091] Table 5: Bearing Verification Results

[0092] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0093] The following are embodiments of the rotating system life analysis system for electric drive systems considering thermal expansion provided in this disclosure. This system and the rotating system life analysis method for electric drive systems considering thermal expansion in the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the rotating system life analysis system for electric drive systems considering thermal expansion, please refer to the embodiments of the rotating system life analysis method for electric drive systems considering thermal expansion.

[0094] The system includes: The modeling module is used to construct a model of the electric drive axle system, including the housing, shaft, and hub, and to perform finite element mesh generation and condensation processing. The rotating system damage calculation module is used to input the torque, speed and gear information extracted from the actual vehicle load spectrum after signal processing into the electric drive axle system model; based on the material SN curve and ISO16281 standard, combined with the system deformation and load characteristics, it calculates the first total damage value of the rotating system under the actual vehicle load spectrum. The load distribution matrix generation module uses the actual vehicle load spectrum, which distinguishes between driving and energy recovery conditions according to gear, and separates torque and speed by gear; it uses the rotational counting method and Markov matrix to count the frequency of occurrence of each torque-speed combination to form the load distribution matrix; The bench load spectrum generation module calculates the second total damage value of the rotating system based on the load distribution matrix and the Palmgren-Miner linear damage theory. The torque is segmented according to a preset number of segments. By increasing the amplitude of each segment and adjusting the number of cycles, the bench load spectrum is generated so that the error between the second total damage value and the first total damage value does not exceed a preset threshold. The bench load spectrum equivalence verification module is used to input the generated bench load spectrum into the electric drive bridge system model to obtain the third total damage value based on the rotating system; if the deviation between the third total damage value and the first total damage value exceeds the allowable range, it returns to adjust the number of segments or the number of cycles until the equivalence requirements are met. The electric drive bridge thermal balance test module is used to conduct electric drive bridge thermal balance tests under windless natural convection environment with a verified equivalent bench load spectrum as the test conditions. After a break-in period of no less than the preset time, thermocouples are arranged around the rotating system and the shell to record the steady-state temperature data when thermal balance is reached under each working condition. The coupled simulation module is used to map the measured steady-state temperature data as the temperature field boundary condition to the corresponding node of the electric drive bridge system model, and apply it together with the bench load spectrum to perform thermo-mechanical multi-field coupled simulation and calculate the total damage value of the rotating system considering the thermal expansion effect. The life assessment conclusion output module is used to compare the total damage value of the rotating system with the first total damage value; if the difference between the two is within the preset allowable range, the total damage value of the rotating system is output as the final life assessment conclusion.

[0095] like Figure 7 As shown, this application also provides an electronic device, including a display module 103, a memory 102, a processor 101, a communication module 104, and a computer program stored in the memory and executable on the processor 101. When the processor 101 executes the program, it implements the steps of a method for analyzing the life of a rotating system of an electric drive system that takes thermal expansion into account.

[0096] In embodiments of the present invention, electronic devices include, but are not limited to, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments described and / or claimed herein.

[0097] In this embodiment, processor 101 may be implemented using at least one of an application-specific integrated circuit, a programmable logic device, a field-programmable gate array, a processor, a controller, a microcontroller, a microprocessor, or an electronic unit designed to perform the functions described herein. In some cases, such an implementation may be implemented within a controller. For software implementation, implementations such as processes or functions may be implemented with separate software modules that allow the performance of at least one function or operation. Software code may be implemented by a software application (or program) written in any suitable programming language, and the software code may be stored in memory and executed by the controller.

[0098] The display module 103 is used to display information input by the user or information provided to the user. The display module 103 may include a display panel, which may be configured in the form of a liquid crystal display, an organic light-emitting diode, or the like.

[0099] The memory 102 can be used to store software programs and various data. The memory 102 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0100] The communication module 104 transmits radio signals to and / or receives radio signals from at least one of a base station, an external terminal, and a server. Such radio signals may include voice call signals, video call signals, or various types of data sent and / or received according to text and / or multimedia messages.

[0101] The present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method for analyzing the life of the rotating system of an electric drive system considering thermal expansion.

[0102] The storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0103] The storage medium stores a program product capable of implementing the methods described above in this specification. In some possible implementations, various aspects of this disclosure may also be implemented as a program product comprising program code that, when run on a terminal device, causes the terminal device to perform the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of this disclosure.

[0104] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion, characterized in that, The methods include: S1: Construct a model of the electric drive axle system including the housing, shaft, and hub, and perform finite element mesh generation and condensation processing; S2: Input the torque, speed and gear information extracted from the actual vehicle load spectrum after signal processing into the electric drive axle system model of S1; Based on the material SN curve and ISO16281 standard, combined with the system deformation and load characteristics, calculate the first total damage value of the rotating system under the actual vehicle load spectrum. S3: Based on the actual vehicle load spectrum used in S2, drive and energy recovery conditions are distinguished by gear, and torque and speed are separated by gear; using the rotational counting method and Markov matrix, the frequency of occurrence of each torque-speed combination is counted to form a load distribution matrix; S4: Based on the load distribution matrix, the second total damage value of the rotating system is calculated using the Palmgren-Miner linear damage theory; the torque is segmented according to the preset number of segments, and the load spectrum of the test bench is generated by increasing the amplitude of each segment and adjusting the number of cycles, so that the error between the second total damage value and the first total damage value does not exceed the preset threshold. S5: Input the bench load spectrum generated in S4 into the electric drive bridge system model in S1 to obtain the third total damage value based on the rotating system. If the deviation between the third total damage value and the first total damage value exceeds the allowable range, return to S4 to adjust the number of segments or the number of cycles until the equivalence requirement is met; S6: Using the equivalent bench load spectrum verified by S5 as the test condition, conduct the electric drive bridge thermal balance test in a windless natural convection environment; after completing a break-in period of no less than the preset time, arrange thermocouples around the rotating system and the shell, and record the steady-state temperature data when thermal equilibrium is reached under each working condition. S7: The steady-state temperature data measured in S6 is used as the temperature field boundary condition, mapped to the corresponding node of the electric drive bridge system model in S1, and applied together with the bench load spectrum in S4. A thermo-mechanical multi-field coupled simulation is performed to calculate the total damage value of the rotating system considering the thermal expansion effect. S8: Compare the total damage value of the rotating system with the first total damage value; If the difference between the two is within the preset allowable range, the total damage value of the rotating system will be output as the final life assessment conclusion.

2. The method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion according to claim 1, characterized in that, S2 specifically includes the following steps: S21: Convert the torque, speed and gear information of each time step in the actual vehicle load spectrum into a load input sequence that can be recognized by MASTA, align the model dynamics solution step size according to the sampling frequency, and insert a transition segment at each gear switching point; S22: In MASTA, call the material SN curve database, specify the corresponding damage slope for the shaft and gear, and call the ISO16281 standard module for bearing life calculation, inputting the actual bearing model, internal geometric parameters and contact load path; S23: Extract the time-varying stress history of each key position of the rotating system, count the bearing raceway, gear tooth root, and shaft shoulder transition area respectively, and accumulate them segment by segment according to the Palmgren-Miner formula based on their respective damage slopes to obtain the first total damage value of the rotating system under the actual vehicle load spectrum.

3. The method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion according to claim 1, characterized in that, S3 specifically includes the following steps: S31: Separate the actual vehicle load spectrum into several subsequences according to gear position, and further divide each subsequence into positive motor output torque and negative motor output torque to form a time torque speed dataset; S32: Using the rotational speed as the reference axis, the torque signal is resampled for each revolution to eliminate the non-periodicity caused by speed change; then, peak-valley extraction is applied to the resampled torque mileage to identify stress cycles and record the amplitude, mean and corresponding speed range of each cycle. S33: Construct a two-dimensional Markov state transition matrix. The state is defined as a preset torque-speed discrete interval. Statistically count the frequency of state transitions between adjacent sampling points to obtain the transition probability matrix. Accumulate the dwell time of each state to form a load distribution matrix.

4. The method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion according to claim 1, characterized in that, S4 specifically includes the following steps: S41. Based on the load distribution matrix, divide the torque interval into preset segments, determine the torque reference value of each sub-interval, and extract the load cycle information within it. S42. For each torque sub-interval, adjust the torque amplitude according to its load cycle information and calculate the number of cycles so that the error between the adjusted total damage value and the first total damage value meets the requirements. S43. Based on the adjusted torque amplitude and number of cycles, generate a bench load spectrum and verify its equivalence by comparing the total damage value. If it does not meet the requirements, return to the adjustment parameters.

5. The method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion according to claim 1, characterized in that, S5 specifically includes the following steps: S51. Organize the test load spectrum into a load sequence that can be recognized by MASTA, and configure simulation parameters for each operating point. S52. Perform transient simulation in MASTA, extract the stress time history of key components, and perform cycle counting to obtain stress cycle data for each working point. S53. Based on the damage slope of each component, accumulate the damage value of stress cycle at each working point to obtain the third total damage value.

6. The method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion according to claim 1, characterized in that, S7 specifically includes the following steps: S71. Based on the location of the measuring points in the thermal equilibrium test, establish the mapping relationship and weight coefficients between them and the nodes of the finite element model; S72. Based on this mapping relationship, the steady-state temperature values ​​of the measuring points are assigned to the model nodes to generate the temperature field distribution corresponding to each working condition of the test load spectrum, and it is defined as the thermal boundary condition for simulation. S73. Activate the temperature dependence of the material's thermal performance parameters in the software, apply the temperature field and load spectrum together, obtain the thermomechanical stress through coupling solution, and calculate the total damage value of the rotating system.

7. The method for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion according to claim 1, characterized in that, S4 also considers all load cycles within a certain torque segment of the actual vehicle load spectrum, denoted as cycles 1 to k, corresponding to cycle numbers n1, n2…n. k Torque T1, T2…T k Combining the damage slope p of the corresponding component in the rotating system, the equivalent torque of this segment is calculated using the following formula. : .

8. A system for analyzing the lifespan of a rotating system in an electric drive system considering thermal expansion, characterized in that, The system is used to implement the method for analyzing the life of rotating parts of an electric drive system considering thermal expansion as described in any one of claims 1 to 7; The system includes: The modeling module is used to construct a model of the electric drive axle system, including the housing, shaft, and hub, and to perform finite element mesh generation and condensation processing. The rotating system damage calculation module is used to input the torque, speed and gear information extracted from the actual vehicle load spectrum after signal processing into the electric drive axle system model; based on the material SN curve and ISO16281 standard, combined with the system deformation and load characteristics, it calculates the first total damage value of the rotating system under the actual vehicle load spectrum. The load distribution matrix generation module uses the actual vehicle load spectrum, which distinguishes between driving and energy recovery conditions according to gear, and separates torque and speed by gear; it uses the rotational counting method and Markov matrix to count the frequency of occurrence of each torque-speed combination to form the load distribution matrix; The bench load spectrum generation module calculates the second total damage value of the rotating system based on the load distribution matrix and the Palmgren-Miner linear damage theory. The torque is segmented according to a preset number of segments. By increasing the amplitude of each segment and adjusting the number of cycles, the bench load spectrum is generated so that the error between the second total damage value and the first total damage value does not exceed a preset threshold. The bench load spectrum equivalence verification module is used to input the generated bench load spectrum into the electric drive bridge system model to obtain the third total damage value based on the rotating system; if the deviation between the third total damage value and the first total damage value exceeds the allowable range, it returns to adjust the number of segments or the number of cycles until the equivalence requirements are met. The electric drive bridge thermal balance test module is used to conduct electric drive bridge thermal balance tests under windless natural convection environment with a verified equivalent bench load spectrum as the test conditions. After a break-in period of no less than the preset time, thermocouples are arranged around the rotating system and the shell to record the steady-state temperature data when thermal balance is reached under each working condition. The coupled simulation module is used to map the measured steady-state temperature data as the temperature field boundary condition to the corresponding node of the electric drive bridge system model, and apply it together with the bench load spectrum to perform thermo-mechanical multi-field coupled simulation and calculate the total damage value of the rotating system considering the thermal expansion effect. The life assessment conclusion output module is used to compare the total damage value of the rotating system with the first total damage value; if the difference between the two is within the preset allowable range, the total damage value of the rotating system is output as the final life assessment conclusion.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for analyzing the life of a rotating system of an electric drive system considering thermal expansion as described in any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for analyzing the life of a rotating system of an electric drive system considering thermal expansion as described in any one of claims 1 to 7.

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