Load compilation method for low-cycle fatigue test of shunt casing
By combining engine field flight parameters and service data, matching overload cycles with aerodynamic cyclic load spectra, and compiling low-cycle fatigue test loads for the splitter casing, the problem of unreasonable load compilation in existing technologies is solved, and the accuracy of life assessment and the rationality of testing are achieved.
Patent Information
- Application Number
- CN202511033621.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-11-07
AI Technical Summary
The lack of a clear method for compiling low-cycle fatigue test loads for shunt casings in the existing technology leads to overly stringent load tests in extreme cases, making it impossible to accurately assess the low-cycle fatigue life of shunt casings.
Based on engine field flight parameters and service data, the damage to the shunt casing is calculated by matching the number of overload cycles with the aerodynamic cyclic load spectrum. Low-cycle fatigue test loads are developed in accordance with the damage equivalence principle, taking into account the combination of aerodynamic and mechanical loads under actual operating conditions.
This achieves accurate reflection of the low-cycle fatigue life of the shunt casing while taking into account the lifespan dispersion, ensuring that the test is more in line with its actual use requirements.
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Figure CN120910995A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of aero-engine power analysis, in particular to a load compiling method for low cycle fatigue test of a splitter casing. BACKGROUND
[0002] The splitter casing is a component of the compressor part of an aero-engine, responsible for transmitting the thrust generated by the engine to the aircraft, and is an important load-bearing and force-transmitting component of the engine. At the same time, the splitter casing is subjected to different types of loads such as aerodynamic thrust and overload during use, and the loads it bears are severe and complex.
[0003] For an aero-engine component, the splitter casing is the most important load-bearing and force-transmitting component in the aero-engine, and the splitter casing is usually not allowed to be damaged or replaced during the entire service life of the engine. Therefore, for the splitter casing, whether the low cycle fatigue load life can meet the engine use requirements is very important. At the same time, the splitter casing is subjected to very complex loads, not only subjected to aerodynamic thrust loads, but also subjected to overload loads generated when the aircraft is in a maneuvering flight, and the combination of aerodynamic thrust loads and overload loads is uncertain, and the combination conditions are very complex.
[0004] Currently, there is no clear method for compiling the low cycle fatigue test load of the splitter casing, and in extreme cases, even the limiting load of the splitter casing is used to carry out the low cycle fatigue test. As the most severe working condition load of the engine, the limiting load used for low cycle fatigue test is obviously too severe, which will cause the low cycle fatigue test of the splitter casing to fail to pass the examination.
[0005] Therefore, a technical solution is needed to compile the low cycle fatigue test load in combination with the service data of the actual working conditions of the splitter casing. SUMMARY
[0006] To achieve the above-mentioned purpose, the present application provides a load compiling method for low cycle fatigue test of a splitter casing, comprising the following steps: Based on the flight parameters of the engine in the field, the number of overloads of the engine under different aerodynamic state load conditions in the service life of the engine is obtained; The flight profile of the engine is obtained, and the aerodynamic cycle load spectrum of the splitter casing is obtained; the aerodynamic cycle load spectrum is composed of cycle types and corresponding cycle numbers; The number of overloads and the aerodynamic cycle load spectrum are matched to obtain the aerodynamic load and maneuvering load combination state corresponding to the maneuvering overload cycle of the steady state stress; in the matching process, the number of overloads under the aerodynamic state is matched with the cycle numbers in the aerodynamic cycle load spectrum, and when matching, the number of overloads is distributed in order from large to small according to the overload coefficient; According to the stress value of the examination part of the splitter duct under the combined state of the aerodynamic load and the maneuvering load, the total damage of the splitter duct is calculated ; According to the damage equivalent principle, the cycle type load of the low cycle fatigue test of the splitter duct under the test cycle load is determined, and the load programming of the low cycle fatigue test is realized.
[0007] The flight parameters include the overload coefficient, and the higher the overload coefficient is, the more stringent the fatigue test requirement is. The aerodynamic state includes cruise, intermediate and afterburning working conditions, and the cycle type is composed of different aerodynamic state combinations.
[0008] The matching process includes the following steps: The aerodynamic state and the corresponding cycle type to be matched are determined; The number of occurrences of the maneuvering overload corresponding to the aerodynamic state is obtained, and the overload coefficients are arranged from large to small; The number of matchable cycles is obtained; The matching queue is constructed, and the number of occurrences of the maneuvering overload and the number of matchable cycles are imported into the matching queue; The serial number matching is performed, and the number of matchable cycles is assigned to the combination state of the cycle type and the overload coefficient according to the matching queue.
[0009] Further, the queue structure of the matching queue includes: serial number, number of matchable cycles, number of to-be-matched, and actual number of matching; When the number of occurrences of the maneuvering overload and the number of matchable cycles are imported into the matching queue, the number of matchable cycles corresponds to the number of to-be-matched with the serial number 1 in the queue, the serial number is arranged from large to small according to the overload coefficient, and the number of to-be-matched with the serial number greater than 1 is empty by default, and the number of matchable cycles corresponds to the overload coefficient. When the serial number matching is performed, if the number of matchable cycles > the number of to-be-matched, the actual number of matching = the number of to-be-matched, and the result of the number of matchable cycles - the actual number of matching is updated into the number of matchable cycles of the next serial number; continue the matching of the next serial number.
[0010] Further, when the serial number matching is performed, if the number of matchable cycles <= the number of to-be-matched, the actual number of matching = the number of matchable cycles, and the serial number matching is ended.
[0011] The calculation method for calculating the total damage of the splitter duct is: Wherein, is the damage of the splitter duct under a certain cycle type, is the total damage of the splitter duct, and n is the total number of cycle types.
[0012] Further, the load programming of the low cycle fatigue test comprises: determining the number of groups of combined loads completed in the low cycle fatigue test process and the number of cycles of each group of loads ; wherein the number of groups of combined loads completed , is the total damage of the low cycle fatigue test of the splitter case, and the total damage of the splitter case is equal; is the damage of the splitter case under a group of combined test loads; the number of cycles of each group of loads is determined by the number of cycles of the maneuvering overload corresponding to the combined state of the aerodynamic load and the maneuvering load.
[0013] Further, when the low cycle fatigue test selects three types of cycles, the load of the three types of cycles is i, k and m respectively, and the number of cycles of the three types of cycle test loads is: a group of loads completes i cycles of type i load, k cycles of type k load, and m cycles of type m load; the cycle type load is determined by the combined state of the aerodynamic load and the maneuvering load; the number of cycles of each group of loads is calculated as follows: , wherein, are coefficients of the multiple relationship between the cycle number of the three types of cycle test loads respectively.
[0014] When the low cycle fatigue test selects three types of cycles, the damage of the splitter case under a group of combined test loads is calculated as follows: wherein: , , are the damages of the splitter case under a single cycle of the low cycle fatigue test load of the three types of cycles respectively.
[0015] According to the present application, the combined state of the aerodynamic load and the maneuvering load can be designed in combination with the service data of the actual working condition of the splitter case, the low cycle fatigue test load of the splitter case under each state is provided based on the cycle number under the combined state, the damages of the splitter case under the flight state and the test state are calculated respectively according to the equal damage principle, and the low cycle fatigue test load programming of the splitter case is realized. Since the low cycle fatigue test load of the splitter case in the present application is more in line with the actual use requirements of the engine splitter case, the low cycle fatigue life thereof can be more accurately reflected under the premise of considering the life dispersion. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is a load compiling method step diagram provided according to an embodiment of the present application; Figure 2 is a load compiling method line compiling shunt casing low cycle fatigue test load spectrum provided according to an embodiment of the present application. DETAILED DESCRIPTION
[0017] The present application provides a load compiling method according to existing field flight data, and based on existing service data statistics shunt casing low cycle fatigue test load data, since such data is more in line with the real use demand of the engine shunt casing, the low cycle fatigue life can be accurately reflected under the premise of considering the life dispersion.
[0018] The specific implementation of the present application will be described in detail below in combination with the drawings of the specification.
[0019] Figure 1 The present application provides a load compiling method step of shunt casing low cycle fatigue test based on service data, comprising: Step S100: based on the flight parameters of the engine in the field, obtaining the number of overloads of the engine under different aerodynamic state load conditions in the life cycle of the engine, and calculating the overload proportion under different aerodynamic states based on the number of overloads; Specifically, the flight parameters in the field include overload coefficient n z (g), the higher the overload coefficient, the more stringent the fatigue test requirement; different aerodynamic states include cruise, intermediate and afterburning working conditions; on this basis, the cycle types that can be constituted by different aerodynamic states include 0-afterburning-0, 0-intermediate-0, cruise-afterburning-cruise, cruise-intermediate-cruise, etc.
[0020] The number of times of maneuvering overload under different aerodynamic states is shown in Table 1:
[0021] The proportion of the number of times of maneuvering overload under different aerodynamic states is shown in Table 2:
[0022] Step S110: obtaining the flight profile of the engine, and obtaining the aerodynamic cycle load spectrum of the shunt casing; In this step, the rainflow counting method is used to obtain the aerodynamic cycle load spectrum of the shunt casing, including: based on the flight profile of the engine, extracting parameters that are strongly related to the aerodynamic load of the shunt casing, then calculating each flight profile parameter in time sequence, and finally obtaining the aerodynamic cycle load spectrum of the shunt casing.
[0023] The aerodynamic cycle load spectrum is composed of cycle types and corresponding cycle numbers, as shown in Table 3: Table 3 Aerodynamic cycle load spectrum
[0024] Step S120: matching the number of overloads with the aerodynamic cycle load spectrum to obtain the aerodynamic load corresponding to the steady stress maneuvering overload cycle; In the matching process, the number of overloads in the aerodynamic state in Table 1 is matched with the cycle number in the aerodynamic cycle load spectrum in Table 3. When matching, the number of overloads is distributed according to the order of the overload factor from large to small.
[0025] When the total number of overloads in the aerodynamic state is greater than the cycle number of the aerodynamic load, the remaining number of overloads in the aerodynamic state is taken as the aerodynamic load, that is, the steady stress maneuvering overload cycle. As shown in Table 4, the matching result of the number of overloads and the aerodynamic cycle in the afterburner state is given.
[0026] Table 4 Matching result of maneuvering load and aerodynamic load
[0027] The specific matching process is as follows: 1) Determine the aerodynamic state and the corresponding cycle type that need to be matched: In the embodiment of the application, the scenario of the aerodynamic state being "afterburner" and the cycle type being "0-afterburner-0" is matched; 2) Obtain the number of occurrences of maneuvering overloads corresponding to the aerodynamic state "afterburner". In this embodiment, the number of occurrences of maneuvering overloads under different overload factors can be obtained from Table 1, and the order is arranged from large to small as shown in Table 5: Table 5 Number of occurrences of maneuvering overloads in the aerodynamic "afterburner" state
[0028] 3) Obtain the number of matchable cycles, that is, the number of cycles corresponding to the cycle type "0-afterburner-0" is 6000 from Table 3; 4) Construct a matching queue, and the queue structure includes: serial number, matchable cycle number, number to be matched, and actual matching number. The number of occurrences of maneuvering overloads and the number of matchable cycles are imported into the matching queue, wherein the number of matchable cycles corresponds to the number to be matched in the queue with the serial number being 1, the serial number is arranged according to the order of the overload factor from large to small, the number to be matched with the serial number greater than 1 is empty by default, and the number of matchable cycles corresponds to the overload factor; In the embodiment of the application, the matching queue to be matched in the order can be constructed as shown in Table 6: Table 6 Matching queue to be matched in the order
[0029] 5) Based on the matching queue, assign the numbers to be matched in ascending order of their sequence numbers to the combined states corresponding to the loop type and overload coefficient. These combined states can be identified by their sequence numbers. When matching by sequence number, if the number of matchable cycles > the number of unmatched cycles, the actual number of matches = the number of unmatched cycles, and the result of the number of matchable cycles minus the actual number of matches is updated into the number of matchable cycles for the next sequence number. Continue matching the next sequence number; If the number of matching cycles is less than or equal to the number of cycles to be matched, the actual number of matches equals the number of matching cycles, and the sequence number matching ends.
[0030] The matching results of the matching queue in this embodiment of the invention are shown in Table 7: Table 7 Matching queues that have completed sequence number matching
[0031] The sequence number in the matching queue corresponds to the combined state of aerodynamic loads and mechanical loads.
[0032] Table 4, generated based on matching various cycle types and overload coefficients, shows each data point corresponding to a combination of aerodynamic and mechanical load states, including: valley state, peak state, number of cycles, and cycle type.
[0033] Step S130: Calculate the damage to the shunt casing based on the stress values of the test parts of the shunt casing under the combined aerodynamic load and mechanical load conditions; In this step, the stress value of the test part of the splitter casing under the combined state of aerodynamic load and mechanical load can be obtained by finite element calculation, and then the life and total damage of the splitter casing can be calculated by finite element calculation based on the stress value.
[0034] The method for calculating the total damage to the shunt casing is as follows: in, Damage to the shunt casing under a certain type of circulation. The total damage to the shunt casing is n, and the total number of cycle types is n.
[0035] Step S140: Determine the load for the low-cycle fatigue test of the shunt casing under the test cyclic load according to the damage equivalence principle, and realize the load compilation for the low-cycle fatigue test.
[0036] In this step, one or more types of cyclic loads are selected to apply low-cycle fatigue test loads to the shunt casing (e.g., Figure 2 As shown in the figure, the damage of various shunt casings under a single cycle of low-cycle fatigue test load was obtained through finite element calculation.
[0037] According to the design requirements, the test load times of different kinds of low cycle fatigue are allocated, and the test load times of three kinds of cycle types i, k and m are selected in the assumption test, and the test load times of the three kinds of cycle types should satisfy the relationship of , at this time, the i cycle type load is completed times, the k cycle type load is completed times, and the m cycle type load is completed times; wherein the cycle type load is determined by the combined state of the aerodynamic load and the maneuvering load generated in step S120.
[0038] The damage calculation method of the test completed one group of loads is as follows: , , are respectively the damage of the single cycle flow splitter cowl under the three kinds of cycle type low cycle fatigue test loads, are respectively the coefficient of the multiple relationship between the cycle times of the three kinds of cycle type test loads, that is, a group of combined test loads contains i cycle type loads, k cycle type loads, m cycle type loads; at this time, the damage of the flow splitter cowl under a group of combined test loads can be obtained as .
[0039] According to the equal damage principle, that is, the total damage of the flow splitter cowl under the low cycle fatigue test is equal to the total damage of the flow splitter cowl calculated in step S130 , the cycle times of the flow splitter cowl under the test load are determined as , wherein is the number of groups of combined loads.
[0040] According to the design requirements of the flow splitter cowl, due to the existence of material dispersion, the low cycle fatigue test cycle number of the flow splitter cowl needs to be multiplied by a dispersion coefficient according to the number of flow splitter cowl test pieces. For example, if there are three test pieces of the flow splitter cowl to carry out the low cycle fatigue test, the dispersion coefficient is 2, and at this time, the final test cycle number is .
[0041] Through the above method, the number of groups of combined loads in the low cycle fatigue test process and the cycle times of each group of loads can be determined, and the load preparation of the low cycle fatigue test can be realized.
[0042] In the application, the combined state of aerodynamic load and maneuvering load is designed in combination with the service data of the splitter casing under actual working conditions, the low cycle fatigue test load of the splitter casing under each state is provided based on the cycle number under the combined state; the damage of the splitter casing under the flight state and the test state is respectively calculated by referring to the equal damage principle, and the low cycle fatigue test load of the splitter casing is compiled.
[0043] The above disclosed are only several specific embodiments of the present application, but the present application is not limited to this, any changes that can be thought of by any person skilled in the art shall fall into the protection scope of the present application.
Claims
1. A load schedule method for low cycle fatigue testing of a split housing, characterized by, The method comprises the following steps: Based on the flight parameters of the engine in the field, the number of overloads of the engine under different aerodynamic state load conditions in the life cycle of the engine is obtained; The flight profile of the engine is obtained, and the aerodynamic cycle load spectrum of the splitter is obtained; the aerodynamic cycle load spectrum is composed of cycle types and corresponding cycle numbers; The number of overloads is matched with the aerodynamic cycle load spectrum to obtain the aerodynamic load and maneuvering load combination state corresponding to the maneuvering overload cycle of the steady state stress; in the matching process, the number of overloads under the aerodynamic state is matched with the cycle numbers in the aerodynamic cycle load spectrum, and when matching, the number of overloads is distributed in order of overload coefficient from large to small; According to the stress value of the examination position of the splitter casing under the combined state of the aerodynamic load and the maneuvering load, the total damage of the splitter casing is calculated ; According to the damage equivalent principle, the cycle type load of the low cycle fatigue test of the splitter under the test cycle load is determined to realize the load preparation of the low cycle fatigue test.
2. The load scheduling method of claim 1, wherein, The flight parameters include the overload coefficient; the higher the overload coefficient, the more stringent the fatigue test requirements; The aerodynamic state includes cruise, intermediate and afterburning working conditions; The cycle type is composed of different aerodynamic state combinations.
3. The load scheduling method of claim 1, wherein, The matching process comprises the following steps: Determine the aerodynamic state and corresponding cycle type that need to be matched; Obtain the number of maneuvering overloads corresponding to the aerodynamic state, and arrange them in order of overload coefficient from large to small; Obtain the number of matchable cycles; Construct a matching queue, and import the number of maneuvering overloads and the number of matchable cycles into the matching queue; Perform sequence number matching, and distribute the number of matchable cycles to the combination state of the cycle type and the overload coefficient according to the matching queue.
4. The load scheduling method of claim 3, wherein, The queue structure of the matching queue comprises: sequence number, number of matchable cycles, number of to-be-matched, and actual number of matching; When the number of maneuvering overloads and the number of matchable cycles are imported into the matching queue, the number of matchable cycles corresponds to the number of to-be-matched with sequence number 1 in the queue, the sequence number is arranged in order of overload coefficient from large to small, and the number of to-be-matched with sequence number greater than 1 is empty by default, and the number of matchable cycles corresponds to the overload coefficient; When the sequence number matching is performed, if the number of matchable cycles > the number of to-be-matched, the actual number of matching = the number of to-be-matched, and the result of the number of matchable cycles minus the actual number of matching is updated into the number of matchable cycles of the next sequence number; continue the matching of the next sequence number.
5. The load scheduling method of claim 4, wherein, When the sequence number matching is performed, if the number of matchable cycles <= the number of to-be-matched, the actual number of matching = the number of matchable cycles, and the sequence number matching is ended.
6. The scheduling method of claim 1, wherein, The calculation method for calculating the total damage of the splitter is: wherein, is the damage of a certain cycle type, is the total damage of the splitter vanes, n is the total number of cycle types.
7. The scheduling method of claim 1, wherein, The load compilation for the low cycle fatigue test comprises: determining the number of groups of combined loads completed in the low cycle fatigue test process , the number of load cycles in each group ; wherein the number of groups of combined loads is completed , is the total damage of the splitter case for the low cycle fatigue test, is equal to the total damage of the splitter case ; is the damage of the splitter case for a group of combined test loads; the number of cycles of each group of loads is determined by the number of cycles of the maneuvering overload corresponding to the combined state of the aerodynamic load and the maneuvering load.
8. The load scheduling method of claim 7, wherein, When the low cycle fatigue test selects three types of cycles, the load of the three types of cycles is i, k and m respectively, and the number of times of the three types of cycle test load is: i cycle type load is completed times, times of k cycle type load, times of m cycle type load; the cycle type load is determined by the combined state of pneumatic load and motor load. Number of load cycles per set The calculation method is: , wherein are coefficients of the multiple relationship between the number of cycles for the cyclic test load of the three cycle types, respectively.
9. The load scheduling method of claim 8, wherein, The low cycle fatigue test selects three kinds of cycle types, and the damage of the flow divider under a group of combined test loads is calculated The calculation method is as follows: wherein: , , are the damages of the single-cycle flow splitter casings for low-cycle fatigue test loads of the three cycle types, respectively.