A method and system for determining rotor cyclic stress under high-temperature long-time working process

Abstract

The application discloses a kind of high-temperature long-time working process under rotor cyclic stress determination method and system, belong to aero-engine technical field.The method includes: obtaining the equivalent stress history of key position of rotor;Using rainflow counting method to extract the peak-valley value stress of type I, III and IV cycle, calculate fatigue damage;Screening high-temperature stress section, obtaining cumulative working time, highest temperature and steady state stress;Obtain the stress life equation of the holding of highest temperature, calculate creep damage;Compare the numerical value of and, determine three different types of cycle stress reference for subsequent fatigue test according to the comparison result;Calculate total damage as test consistency reference.The present application dynamically determines test stress reference based on the proportional relationship between fatigue damage and creep damage, adopts differentiated processing strategy for different damage dominant mode, significantly improves the accuracy of life assessment and the representativeness of test verification of rotor under high-temperature long-time working condition.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a method and system for determining rotor cyclic stress under high-temperature, long-term operating conditions. Background Technology

[0002] The compressor stage rotor and turbine rotor of an aero-engine typically operate under high-temperature conditions. During this operating process, not only fatigue damage but also significant creep damage occurs. Currently, fatigue damage assessment of rotors during their operating process considers the impact of temperature differences at various points in the stress history of critical components on fatigue performance differences. Generally, the stress history of critical components at different temperatures is converted to a specific temperature based on the ratio of tensile strength at corresponding temperatures at each point in time.

[0003] Currently, stress treatment methods in fatigue damage assessment only consider fatigue damage and do not account for creep damage. This approach is suitable for rotors operating at low temperatures or for short periods under high-temperature conditions. However, for rotors subjected to high temperatures and long-term operation, creep damage cannot be ignored. Current methods, by failing to consider the impact of creep damage, result in unreasonable determinations of rotor fatigue damage, posing a risk of premature fatigue failure within the rotor's service life and jeopardizing engine safety. Therefore, a reasonable method for determining rotor cyclic stress under high-temperature, long-term operation is particularly important. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects of the prior art and, in accordance with the principle of equivalent life damage of aero-engine rotors, considers both the influence of fatigue damage and the contribution of creep damage, and provides a method and system for determining rotor cyclic stress under high temperature and long-term operation, so as to achieve reasonable determination of rotor cyclic stress, effectively obtain rotor fatigue damage, and provide support for the use and maintenance of aero-engine rotors.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for determining rotor cyclic stress under high-temperature long-term operating conditions, comprising the following steps: S1: Conduct finite element strength analysis calculations of the rotor under typical operating conditions to obtain the key components at each time point. stress and corresponding temperature This allows for the determination of the stress and temperature histories of key rotor components; then, the key rotor components are subjected to different temperatures. Stress Conversion to the lowest temperature corresponding to fatigue life The equivalent stress history under the following conditions; S2: The equivalent stress history is counted using the rainflow counting method to obtain the peak and valley stresses corresponding to Type I cycles. , Peak and trough values ​​corresponding to type III cycles , And the peak and valley stresses corresponding to type IV cycles. , The fatigue life of key rotor components under types I, III, and IV cycling was obtained based on the fatigue life equation of the rotor material. , , Combined with the number of working cycles of the rotor under types I, III, and IV cycles , , Calculate fatigue damage of key rotor components during operating process. ; S3: Based on the melting point temperature of the rotor material From the stress and temperature histories, samples with temperatures higher than 0.4℃ were selected. The high-temperature stress section was identified, and the cumulative working time corresponding to this high-temperature stress section was obtained. Maximum temperature and steady-state stress ; S4: Obtain rotor material at the highest temperature The endurance stress life equation is used to calculate the stress in the steady state. The following continuous working time Then calculate creep damage. ; S5: Compare the creep damage With fatigue damage The numerical value is used to determine the cyclic stress benchmark for subsequent fatigue testing of components based on the comparison results. The cyclic stress benchmark is divided into the following three types: First Cyclic Stress Reference: When When this happens, the peak and valley stresses corresponding to the type I cycle will be... , As the cyclic peak and valley stresses, the temperature of the cyclic stress is ; Second cyclic stress reference: when When this happens, the valley stress corresponding to the type I cycle will be... As the cyclic valley stress, the steady-state stress The temperature at which the cyclic peak stress is located is... ; Third cycle stress benchmark: Otherwise, the peak and valley stresses corresponding to the first type of cycle will be used. , The peak and valley stresses of the first cycle are defined by the temperature of the stress in the first cycle. The valley stress corresponding to the type I cycle; As the valley stress of the second cycle, the steady-state stress The peak stress of the second cycle, the temperature of the stress in the second cycle is... ; S6: Based on the fatigue damage and creep damage Calculate total damage The total damage This is to ensure that the test damage during subsequent fatigue testing is consistent with the damage during the working process.

[0007] Further, in step S3, the steady-state stress The method for determining it is as follows: Select from the high-temperature stress sections that meet the requirements The high-temperature, high-stress condition, where n is the rotational speed at each time point. This is the maximum rotational speed during the operating process; In the aforementioned high-temperature, high-stress condition, three consecutive stresses are selected. , , and corresponding time , , ,in Calculate the stress correlation coefficient using the following formula. , :

[0008]

[0009] When the stress correlation coefficient , Take when the following conditions are met As the steady-state stress σwt:

[0010] in, This is a preset threshold.

[0011] Furthermore, the preset threshold The value is 0.1.

[0012] Further, in step S4, the endurance stress life equation is:

[0013] in, t is time. For stress, The test temperature is given, and b0~b4 are material coefficients.

[0014] Furthermore, if the material handbook lacks a maximum temperature... The sustained stress life equation under the given conditions was used to obtain the highest temperature through experiments. Based on the sustained performance data, follow these steps to establish the maximum temperature. The following is the endurance stress life equation: At least four sets of endurance tests with different stresses should be conducted, with the test times corresponding to the stresses in each set being uniformly distributed on the logarithmic life coordinate. At least three specimens should be tested under each stress, and the maximum test stress should be greater than the peak stress corresponding to Type I cycles. The minimum test stress is less than the steady-state stress. ; After obtaining the data on the sustained stress and test time at each test point, according to Regression analysis was performed using the functional form of the equation to obtain the highest temperature. The following is the endurance stress life equation; where, Let t be the stress and t be the time. is a coefficient.

[0015] Furthermore, the fatigue damage According to the formula calculate.

[0016] Furthermore, the cyclic stress benchmark determined in step S5 is used for subsequent fatigue test verification, and the test verification must meet the following requirements: If the first cyclic stress reference is used, then under cyclic stress and at a test temperature of Conduct the experiment, with a minimum number of experimental cycles. And ensure that the test damage is consistent with the total damage. Consistent; If the second cyclic stress benchmark is used, the peak stress accumulation holding time shall not be less than and ensure that the test damage is related to Consistent; If the third cyclic stress reference is used, then the stress and temperature in the first cycle are... The number of test cycles should not be less than And in the second cycle, the peak stress and temperature were The cumulative load holding time is not less than At the same time, ensure that the test damage and Consistent.

[0017] Furthermore, the rotor is an outlet stage rotor of an aero-engine compressor or a turbine rotor.

[0018] In a second aspect, the present invention provides a rotor cyclic stress determination system under high-temperature long-term operating conditions, comprising: The first acquisition module is used to perform finite element strength analysis calculations of the rotor under typical operating conditions, obtaining the key components at each time point. stress and corresponding temperature This allows for the determination of the stress and temperature histories of key rotor components; then, the key rotor components are subjected to different temperatures. Stress Conversion to the lowest temperature corresponding to fatigue life The equivalent stress history under the following conditions; The fatigue damage calculation module is used to count the equivalent stress history using the rainflow counting method to obtain the peak and valley stresses corresponding to Type I cycles. , Peak and trough values ​​corresponding to type III cycles , And the peak and valley stresses corresponding to type IV cycles. , The fatigue life of key rotor components under types I, III, and IV cycling was obtained based on the fatigue life equation of the rotor material. , , Combined with the number of working cycles of the rotor under types I, III, and IV cycles , , Calculate fatigue damage of key rotor components during operating process. ; The creep parameter extraction module is used to extract parameters based on the melting point temperature of the rotor material. From the stress and temperature histories, samples with temperatures higher than 0.4℃ were selected. The high-temperature stress section was identified, and the cumulative working time corresponding to this high-temperature stress section was obtained. Maximum temperature and steady-state stress ; The creep damage calculation module is used to obtain the rotor material at the highest temperature. The endurance stress life equation is used to calculate the stress in the steady state. The following continuous working time Then calculate creep damage. ; The total damage calculation module is used to calculate the fatigue damage. and creep damage Calculate total damage ; Cyclic stress benchmark determination module, used to compare the creep damage With fatigue damage The numerical value is used to determine the cyclic stress benchmark for subsequent fatigue testing of components based on the comparison results. The cyclic stress benchmark is divided into the following three types: First Cyclic Stress Reference: When When this happens, the peak and valley stresses corresponding to the type I cycle will be... , As the cyclic peak and valley stresses, the temperature of the cyclic stress is ; Second cyclic stress reference: when When this happens, the valley stress corresponding to the type I cycle will be... As the cyclic valley stress, the steady-state stress The temperature at which the cyclic peak stress is located is... ; Third cycle stress benchmark: Otherwise, the peak and valley stresses corresponding to the first type of cycle will be used. , The peak and valley stresses of the first cycle are defined by the temperature of the stress in the first cycle. The valley stress corresponding to the type I cycle; As the valley stress of the second cycle, the steady-state stress The peak stress of the second cycle, the temperature of the stress in the second cycle is... .

[0019] Furthermore, in the creep parameter extraction module, the steady-state stress The method for determining it is as follows: Select from the high-temperature stress sections that meet the requirements The high-temperature, high-stress condition, where n is the rotational speed at each time point. This is the maximum rotational speed during the operating process; In the aforementioned high-temperature, high-stress condition, three consecutive stresses are selected. , , and corresponding time , , ,in Calculate the stress correlation coefficient using the following formula. , :

[0020]

[0021] When the stress correlation coefficient , Take when the following conditions are met As the steady-state stress σwt:

[0022] in, The preset threshold is δ, and the preset threshold δ is 0.1.

[0023] Compared with the prior art, the beneficial effects of the present invention include: 1. This invention, based on the principle of equivalent life damage of aero-engine rotors, considers both the impact of fatigue damage and the contribution of creep damage, enabling the reasonable determination of rotor cyclic stress and effectively obtaining rotor fatigue damage, thus providing support for the use and maintenance of aero-engine rotors.

[0024] 2. This invention proposes a classification decision mechanism based on the relative proportion of fatigue damage and creep damage, according to creep damage... With fatigue damage The ratio dynamically determines three different cyclic stress benchmarks. When creep damage is small, a pure fatigue cyclic stress benchmark is used. The test was conducted at the specified temperature; when fatigue damage was small, a combined cyclic stress reference of "fatigue trough value + creep steady-state stress" was used. The holding time is assessed at different temperatures; when both are comparable, a composite cyclic stress benchmark is used to assess both damage mechanisms simultaneously. This differentiated treatment strategy targeting different damage-dominant modes can more accurately reflect the damage mechanism under the actual operating history of the rotor, significantly improving the accuracy of life assessment.

[0025] 3. This invention addresses total damage. The calculation provides a quantitative consistency benchmark for subsequent fatigue test verification, ensuring that the test damage is equivalent to the actual working damage, thereby improving the safety and reliability of the rotor during its service life.

[0026] 4. The evaluation method and system provided by this invention are easy to operate, highly engineering-operable, and can meet engineering needs. They can be widely applied to the life evaluation and test verification of compressor stage rotors and turbine rotors in aero-engines. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1This is a flowchart illustrating the method for determining rotor cyclic stress under high-temperature long-term operation according to an embodiment of the present invention. Figure 2 This is a stress history curve of a key part of the rotor in an embodiment of the present invention; Figure 3 This is a temperature history curve of a key part of the rotor in an embodiment of the present invention; Figure 4 This is a cyclic stress curve showing minimal rotor creep damage in an embodiment of the present invention; Figure 5 This is a cyclic stress curve showing minimal rotor fatigue damage in an embodiment of the present invention; Figure 6 This is a cyclic stress curve diagram of rotor fatigue and creep damage in an embodiment of the present invention. Detailed Implementation

[0029] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0030] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Example 1 This invention provides a method for determining rotor cyclic stress under high-temperature, long-term operating conditions, such as... Figure 1 As shown, the method includes the following steps: S1: Acquisition and Conversion of Stress and Temperature Histories Specifically, finite element strength analysis calculations were performed on the turbine rotor of a certain type of aero-engine under typical operating cycles. The "typical operating cycle" refers to a representative working cycle of the engine in actual use, such as a standard mission profile of takeoff-cruise-landing. Through finite element analysis, the key components of the rotor at each time point were obtained. stress and corresponding temperature This allows for the determination of the stress history in key parts of the rotor (such as...). Figure 2 (as shown) and temperature history (as shown) Figure 3 (As shown).

[0032] In this embodiment of the invention, the key component refers to the assessment location that plays a controlling role in the rotor life evaluation, as determined by finite element strength analysis, such as stress concentration areas like the turbine disk center, bolt holes, and rounded corners. This embodiment of the invention uses the high-pressure turbine disk center as the key component for illustration.

[0033] Then, the key components of the rotor were subjected to different temperatures. Stress Conversion to the lowest temperature corresponding to fatigue life The equivalent stress history under the given conditions. This refers to the temperature at which the material's fatigue life is lowest, typically the lowest temperature encountered by the disk during its typical operating cycle or a reference temperature. The conversion method can employ the tensile strength ratio method, a method already in use.

[0034] S2: Fatigue damage Calculation Specifically, the equivalent stress history was counted using the rainflow counting method, and three typical stress cycles were extracted: Type I Cycle (Main Cycle): Corresponds to large-amplitude stress cycles such as takeoff and landing, with peak and trough stress values ​​denoted as... , ; Type III Cycle (Sub-Cycle 1): Corresponds to a moderate amplitude stress cycle of slow-maximum-slow, with peak and trough stress values ​​denoted as... , ; Type IV Cycle (Sub-Cycle 2): Corresponds to small-amplitude stress cycles such as cruise-maximum-cruise, with peak and trough stresses denoted as... , .

[0035] Then, based on the fatigue life equation for the rotor material (provided by the material handbook or obtained through experiments), the fatigue life of key rotor components under Class I, III, and IV cycles is obtained. , , Fatigue life N refers to the number of cycles required for a material to fail under this type of cyclic stress.

[0036] Finally, the number of working cycles of type I, III, and IV cycles experienced by the rotor in a typical working process (such as a flight takeoff and landing) is considered. , , Fatigue damage was calculated according to Miner's linear cumulative damage theory:

[0037] This formula represents the linear superposition of damage from different types of cycles, yielding the fatigue damage of critical rotor components during the operating process. .

[0038] S3: High-Temperature Stress Section Identification and Stress in Steady State The determination Specifically, based on the melting point temperature of the rotor material (This information can be found in the materials handbook.) From the stress and temperature histories obtained in step S1, select samples with temperatures higher than 0.4°C. The high-temperature stress section. 0.4 It is a threshold commonly used in engineering to determine whether creep is significant. When the temperature is 40% higher than the melting point of the material, the creep effect cannot be ignored.

[0039] The following parameters were obtained from this high-temperature stress zone: cumulative working time. This refers to the total time the rotor operates in the high-temperature range; the highest temperature. That is, the highest temperature occurring in the high-temperature range; steady-state stress. That is, the maximum speed during the working process. The stable stress value below.

[0040] Wherein, the steady-state stress The method for determining it is as follows: First, select those that meet the requirements from the high-temperature stress range. The high-temperature, high-stress condition, where n is the rotational speed at each time point. This represents the maximum rotational speed during the operating process. This screening criterion is used to identify high-stress conditions approaching the maximum rotational speed.

[0041] Then, from the selected high-temperature, high-state stresses, three consecutive stresses are chosen. , , and corresponding time , , ,in Calculate the stress correlation coefficient using the following formula. , :

[0042]

[0043] and This reflects the rate of change of stress over time; a smaller value indicates more stable stress. When the stress correlation coefficient... , Take when the following conditions are met. Stress in a stable state .

[0044]

[0045] in, The preset threshold δ is a small value. In this embodiment of the invention, the preset threshold δ is set to 0.1. This value is based on engineering experience; when the rate of change of stress over time is less than 0.1 MPa / s, the stress can be considered to have reached a stable state.

[0046] S4: Creep damage Calculation Specifically, obtaining the rotor material at its highest temperature The grappling stress life equation describes the relationship between stress and time to fracture of a material at a given temperature. Its general form (which can be found in material handbooks) is:

[0047] in, , where is absolute temperature. t is time. For stress, Where b0, b1, b2, b3, and b4 represent the test temperature, and b0, b1, b2, b3, and b4 are material constants (material constants obtained through regression analysis of material rupture performance tests). This equation incorporates the effect of temperature on the stress-life relationship and can be used to calculate rupture life at any temperature.

[0048] If the material manual lacks the maximum temperature The sustained stress life equation requires obtaining the highest temperature through experiments. Based on the sustained performance data, follow these steps to establish the maximum temperature. The following is the endurance stress life equation: At least four sets of endurance tests with different stresses were conducted, and the test times corresponding to the stresses in each set of tests were evenly distributed on the logarithmic lifetime coordinate. No fewer than three specimens should be used under each stress to ensure the statistical reliability of the data; The maximum test stress is greater than the peak stress corresponding to Type I cycle. The minimum test stress is less than the steady-state stress. This is to ensure that the test range covers the actual working stress.

[0049] After obtaining the data on the sustained stress and test time at each test point, a regression analysis was performed according to the following functional form to obtain the maximum temperature. The following is the endurance stress life equation.

[0050]

[0051] in, Let t be the stress and t be the time. The coefficients are given. This equation is a general equation at a fixed temperature. The simplified form below.

[0052] Using this equation, the stress in the steady state can be calculated. The following continuous working time Then, creep damage is calculated:

[0053] This formula is based on the time fraction rule, which represents the ratio of the cumulative time spent working at high temperatures to the total time that can be withstood under that stress.

[0054] S5: Classification decision based on damage ratio Specifically, comparing creep damage With fatigue damage The numerical value is used to determine the cyclic stress benchmark for subsequent fatigue testing of components based on the comparison results. In this embodiment of the invention, different cyclic stress benchmarks are dynamically selected based on the different damage-dominant mechanisms, and are divided into three types: First cyclic stress reference (small creep damage): When At this point, fatigue damage is dominant, and creep damage is negligible. At this time, the peak and trough stress values ​​corresponding to type I cycles are... , As the cyclic peak and valley stresses, the temperature of the cyclic stress is The cyclic stress curve corresponding to this benchmark is as follows: Figure 4 As shown, it is essentially a pure fatigue cycle.

[0055] Second cycle stress reference (less fatigue damage): When At this point, creep damage is dominant, while fatigue damage is relatively minor. At this time, the valley stress corresponding to type I cycle is... As the cyclic valley stress, the steady-state stress The temperature at which the cyclic peak stress is located is... The key feature of this benchmark is that the valley stress is taken from the valley of the fatigue cycle, and the peak stress is taken from the creep steady-state stress, forming a combined cycle of "fatigue valley + creep steady-state stress," focusing on the holding time at high temperatures. The corresponding cyclic stress curve is shown below. Figure 5 As shown.

[0056] Third Cyclic Stress Reference (Equivalent to Both): When neither is satisfied nor At this point, it indicates that both fatigue damage and creep damage are not negligible. Therefore, a composite cyclic benchmark is used: the peak and valley stresses corresponding to Type I cycles are... , The peak and trough stresses of the first cycle are defined by the temperature of the stress in the first cycle. The valley stress corresponding to type I cycle; As the valley stress of the second cycle, the steady-state stress The peak stress of the second cycle is at the temperature of the stress in the second cycle. This benchmark simultaneously assesses fatigue damage (through the first cycle) and creep damage (through the hold-load time of the second cycle), and its corresponding cyclic stress curves are shown below. Figure 6 As shown.

[0057] This damage ratio-based classification decision-making mechanism can employ the most effective experimental simulation methods for different damage-dominant modes, significantly improving the representativeness and accuracy of experimental verification.

[0058] S6: Total Damage Calculation and Experimental Verification Benchmark Specifically, based on fatigue damage and creep damage Calculate the total damage:

[0059] Total damage It is a dimensionless quantity representing the total damage accumulated by the rotor under typical operating conditions. When When the value reaches 1, the rotor is considered to have failed.

[0060] The cyclic stress benchmark determined in step S5 is used for subsequent fatigue test verification, and the test verification must meet the requirements of total damage. The consistency requirements are as follows: If the first cyclic stress reference is used, then under cyclic stress and at the test temperature... Conduct the experiment, with a minimum number of experimental cycles. And ensure that the test damage of the rotor during fatigue testing is equal to the total damage during the operating process. Consistent. The formula for calculating the number of test cycles here is based on the damage equivalence principle, converting the damage equivalence of Class III and IV cycles into the number of cycles of Class I cycles.

[0061] If the second cyclic stress benchmark is used, the peak stress accumulation holding time should not be less than And ensure that the test damage of the rotor during fatigue testing is equal to the total damage during the operating process. Consistent.

[0062] If the third cyclic stress reference is used, then the stress and temperature in the first cyclic are... The number of test cycles should not be less than And in the second cycle, the peak stress and temperature were The cumulative load holding time is not less than At the same time, ensure that the test damage of the rotor during fatigue testing is equal to the total damage during the operating process. Consistent.

[0063] It should be noted that the method described in the embodiments of the present invention is not limited to a specific type of rotor. Any rotor component subjected to both fatigue and creep damage under high-temperature, long-term operating conditions can be subjected to the method provided in the embodiments of the present invention to determine cyclic stress. In particular, the method described in the embodiments of the present invention is especially applicable to compressor outlet stage rotors and turbine rotors in the field of aero-engines. These two types of rotors are characterized by high operating temperatures, complex loads, and strict life requirements. Applying the method described in the embodiments of the present invention can more accurately assess their actual damage state, providing technical support for life determination and life extension.

[0064] Example 2 This invention also provides a system for determining rotor cyclic stress under high-temperature, long-term operating conditions. This system includes multiple functional modules, each corresponding one-to-one with the method steps in Embodiment 1. The system includes: The first acquisition module is used to perform finite element strength analysis calculations of the rotor under typical operating conditions, obtaining the key components at each time point. stress and corresponding temperature This allows for the determination of the stress and temperature histories of key rotor components; then, the key rotor components are subjected to different temperatures. Stress Conversion to the lowest temperature corresponding to fatigue life The equivalent stress history is shown below. This module corresponds to step S1 of the method, and its function is to provide basic data input for subsequent analysis.

[0065] The fatigue damage calculation module is used to count the equivalent stress history using the rainflow counting method to obtain the peak and valley stresses corresponding to Type I cycles. , Peak and trough values ​​corresponding to type III cycles , And the peak and valley stresses corresponding to type IV cycles. , The fatigue life of key rotor components under types I, III, and IV cycling was obtained based on the fatigue life equation of the rotor material. , , Combined with the number of working cycles of the rotor under types I, III, and IV cycles , , Calculate fatigue damage of key rotor components during operating process. This module corresponds to step S2 in the method, and its function is to quantify fatigue damage.

[0066] The creep parameter extraction module is used to extract parameters based on the melting point temperature of the rotor material. From the stress and temperature histories, samples with temperatures higher than 0.4℃ were selected. The high-temperature stress section was identified, and the cumulative working time corresponding to this high-temperature stress section was obtained. Maximum temperature and steady-state stress This module corresponds to the first half of method step S3.

[0067] In a preferred embodiment, the creep parameter extraction module includes steady-state stress. The determination method is as follows: select those that meet the requirements from the high-temperature stress range. The high-temperature, high-stress condition, where n is the rotational speed at each time point. The maximum rotational speed during the working process; three consecutive stresses are selected from the high-temperature, high-stress conditions. , , and corresponding time , , ,in Calculate the stress correlation coefficient using the following formula. , :

[0068]

[0069] When the stress correlation coefficient , Take when the following conditions are met As the steady-state stress σwt:

[0070] in, A preset threshold is set, and the preset threshold δ is set to 0.1. This preferred scheme corresponds to the details of determining the steady-state stress in step S3 of the method. Its function is to accurately identify the steady-state stress from the high-temperature stress range, providing a reliable stress input for creep damage calculation.

[0071] The creep damage calculation module is used to obtain the rotor material at the highest temperature. The endurance stress life equation is used to calculate the stress in the steady state. The following continuous working time Then calculate creep damage. This module corresponds to step S4 of the method, and its function is to quantify creep damage.

[0072] The total damage calculation module is used to calculate the fatigue damage. and creep damage Calculate total damage This module corresponds to the first half of step S6 in the method, and its function is to linearly superimpose the two types of damage to obtain the total damage.

[0073] Cyclic stress benchmark determination module, used to compare the creep damage With fatigue damage The numerical value is used to determine the cyclic stress benchmark for subsequent component fatigue testing verification based on the comparison results. This module corresponds to method step S5, which executes the following classification decision rules: First Cyclic Stress Reference: When When this happens, the peak and valley stresses corresponding to the type I cycle will be... , As the cyclic peak and valley stresses, the temperature of the cyclic stress is ; Second cyclic stress reference: when When this happens, the valley stress corresponding to the type I cycle will be... As the cyclic valley stress, the steady-state stress The temperature at which the cyclic peak stress is located is... ; Third cycle stress benchmark: Otherwise, the peak and valley stresses corresponding to the first type of cycle will be used. , The peak and valley stresses of the first cycle are defined by the temperature of the stress in the first cycle. The valley stress corresponding to the type I cycle; As the valley stress of the second cycle, the steady-state stress The peak stress of the second cycle, the temperature of the stress in the second cycle is... .

[0074] This module can intelligently select the most suitable cyclic stress benchmark for subsequent test verification based on the relative magnitude of fatigue damage and creep damage under actual working conditions, thereby ensuring that the test damage is equivalent to the actual working damage and improving the accuracy of life assessment.

[0075] The aforementioned modules can be integrated into a single computer system, with each module's function implemented through software programs. This system can serve as a subsystem of an aero-engine life management platform, providing technical support for the determination and extension of engine rotor life.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining rotor cyclic stress under high-temperature, long-term operating conditions, characterized in that, Includes the following steps: S1: Conduct finite element strength analysis calculations of the rotor under typical operating conditions to obtain the key components at each time point. stress and corresponding temperature This allows for the determination of the stress and temperature histories of key rotor components; then, the key rotor components are subjected to different temperatures. Stress Conversion to the lowest temperature corresponding to fatigue life The equivalent stress history under the following conditions; S2: The equivalent stress history is counted using the rainflow counting method to obtain the peak and valley stresses corresponding to Type I cycles. , Peak and trough values ​​corresponding to type III cycles , And the peak and valley stresses corresponding to type IV cycles. , The fatigue life of key rotor components under types I, III, and IV cycling was obtained based on the fatigue life equation of the rotor material. , , Combined with the number of working cycles of the rotor under types I, III, and IV cycles , , Calculate fatigue damage of key rotor components during operating process. ; S3: Based on the melting point temperature of the rotor material From the stress and temperature histories, samples with temperatures higher than 0.4℃ were selected. The high-temperature stress section was identified, and the cumulative working time corresponding to this high-temperature stress section was obtained. Maximum temperature and steady-state stress ; S4: Obtain rotor material at the highest temperature The endurance stress life equation is used to calculate the stress in the steady state. The following continuous working time Then calculate creep damage. ; S5: Compare the creep damage With fatigue damage The numerical value is used to determine the cyclic stress benchmark for subsequent fatigue testing of components based on the comparison results. The cyclic stress benchmark is divided into the following three types: First Cyclic Stress Reference: When When this happens, the peak and valley stresses corresponding to the type I cycle will be... , As the cyclic peak and valley stresses, the temperature of the cyclic stress is ; Second cyclic stress reference: when When this happens, the valley stress corresponding to the type I cycle will be... As the cyclic valley stress, the steady-state stress The temperature at which the cyclic peak stress is located is... ; Third cycle stress benchmark: Otherwise, the peak and valley stresses corresponding to the first type of cycle will be used. , The peak and trough stresses of the first cycle are defined by the temperature of the stress in the first cycle. ; The valley stress corresponding to the type I cycle As the valley stress of the second cycle, the steady-state stress The peak stress of the second cycle, the temperature of the stress in the second cycle is... ; S6: Based on the fatigue damage and creep damage Calculate total damage The total damage This is to ensure that the test damage during subsequent fatigue testing is consistent with the damage during the working process.

2. The method according to claim 1, characterized in that, In step S3, the steady-state stress The method for determining it is as follows: Select from the high-temperature stress sections that meet the requirements The high-temperature, high-stress condition, where n is the rotational speed at each time point. This is the maximum rotational speed during the operating process; In the aforementioned high-temperature, high-stress condition, three consecutive stresses are selected. , , and corresponding time , , ,in Calculate the stress correlation coefficient using the following formula. , : When the stress correlation coefficient , Take when the following conditions are met As the steady-state stress σwt: in, This is a preset threshold.

3. The method according to claim 2, characterized in that, The preset threshold The value is 0.

1.

4. The method according to claim 1, characterized in that, In step S4, the endurance stress life equation is: in, , t is time. For stress, The test temperature is given, and b0~b4 are material coefficients.

5. The method according to claim 1, characterized in that, If the material manual lacks the maximum temperature The sustained stress life equation under the given conditions was used to obtain the highest temperature through experiments. Based on the sustained performance data, follow these steps to establish the maximum temperature. The following is the endurance stress life equation: At least four sets of endurance tests with different stresses should be conducted, with the test times corresponding to the stresses in each set being uniformly distributed on the logarithmic life coordinate. At least three specimens should be tested under each stress, and the maximum test stress should be greater than the peak stress corresponding to Type I cycles. The minimum test stress is less than the steady-state stress. ; After obtaining the data on the sustained stress and test time at each test point, according to Regression analysis was performed using the functional form of the equation to obtain the highest temperature. The following is the endurance stress life equation; where, Let t be the stress and t be the time. is a coefficient.

6. The method according to claim 1, characterized in that, fatigue damage According to the formula calculate.

7. The method according to claim 1, characterized in that, The cyclic stress benchmark determined in step S5 is used for subsequent fatigue test verification, and the test verification must meet the following requirements: If the first cyclic stress reference is used, then under cyclic stress and at a test temperature of Conduct the experiment, with a minimum number of experimental cycles. And ensure that the test damage is consistent with the total damage. Consistent; If the second cyclic stress benchmark is used, the peak stress accumulation holding time shall not be less than and ensure that the test damage is related to Consistent; If the third cyclic stress reference is used, then the stress and temperature in the first cycle are... The number of test cycles should not be less than And in the second cycle, the peak stress and temperature were The cumulative load holding time is not less than At the same time, ensure that the test damage and Consistent.

8. The method according to claim 1, characterized in that, The rotor is either the outlet stage rotor of an aero-engine compressor or a turbine rotor.

9. A system for determining rotor cyclic stress under high-temperature, long-term operating conditions, characterized in that, include: The first acquisition module is used to perform finite element strength analysis calculations of the rotor under typical operating conditions, obtaining the key components at each time point. stress and corresponding temperature This allows for the determination of the stress and temperature histories of key rotor components; then, the key rotor components are subjected to different temperatures. Stress Conversion to the lowest temperature corresponding to fatigue life The equivalent stress history under the following conditions; The fatigue damage calculation module is used to count the equivalent stress history using the rainflow counting method to obtain the peak and valley stresses corresponding to Type I cycles. , Peak and trough values ​​corresponding to type III cycles , And the peak and valley stresses corresponding to type IV cycles. , The fatigue life of key rotor components under types I, III, and IV cycling was obtained based on the fatigue life equation of the rotor material. , , Combined with the number of working cycles of the rotor under types I, III, and IV cycles , , Calculate fatigue damage of key rotor components during operating process. ; The creep parameter extraction module is used to extract parameters based on the melting point temperature of the rotor material. From the stress and temperature histories, samples with temperatures higher than 0.4℃ were selected. The high-temperature stress section was identified, and the cumulative working time corresponding to this high-temperature stress section was obtained. Maximum temperature and steady-state stress ; The creep damage calculation module is used to obtain the rotor material at the highest temperature. The endurance stress life equation is used to calculate the stress in the steady state. The following continuous working time Then calculate creep damage. ; The total damage calculation module is used to calculate the fatigue damage. and creep damage Calculate total damage ; Cyclic stress benchmark determination module, used to compare the creep damage With fatigue damage The numerical value is used to determine the cyclic stress benchmark for subsequent fatigue testing of components based on the comparison results. The cyclic stress benchmark is divided into the following three types: First Cyclic Stress Reference: When When this happens, the peak and valley stresses corresponding to the type I cycle will be... , As the cyclic peak and valley stresses, the temperature of the cyclic stress is ; Second cyclic stress reference: when When this happens, the valley stress corresponding to the type I cycle will be... As the cyclic valley stress, the steady-state stress The temperature at which the cyclic peak stress is located is... ; Third cycle stress benchmark: Otherwise, the peak and valley stresses corresponding to the first type of cycle will be used. , The peak and valley stresses of the first cycle are defined by the temperature of the stress in the first cycle. ; The valley stress corresponding to the type I cycle As the valley stress of the second cycle, the steady-state stress The peak stress of the second cycle, the temperature of the stress in the second cycle is... .

10. The system according to claim 9, characterized in that, In the creep parameter extraction module, the steady-state stress The method for determining it is as follows: Select from the high-temperature stress sections that meet the requirements The high-temperature, high-stress condition, where n is the rotational speed at each time point. This is the maximum rotational speed during the operating process; In the aforementioned high-temperature, high-stress condition, three consecutive stresses are selected. , , and corresponding time , , ,in Calculate the stress correlation coefficient using the following formula. , : When the stress correlation coefficient , Take when the following conditions are met As the steady-state stress σwt: in, The preset threshold is δ, and the preset threshold δ is 0.1.

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