Method and system for predicting twist-off torque of torque transmission shaft of aero-engine

Abstract

The invention discloses an aero-engine torque transmission shaft twist-off torque prediction method and system, and belongs to the technical field of aero-engines, and the prediction method comprises the steps: correcting a stress-strain curve of a material according to a mechanical property measurement result of a torque transmission shaft; establishing a finite element model of the torque transmission shaft; and based on the finite element model of the torque transmission shaft, performing finite element analysis on the finite element model of the torque transmission shaft by adopting the corrected stress-strain curve, and determining the twist-off torque of the torque transmission shaft. According to the method, the material characteristic influence of the torque transmission shaft is considered, meanwhile, the influence of a special structure is also considered, the twist-off torque of the torque transmission shaft of the complex structure can be predicted by combining a material stress-strain curve, and the error is lt; the prediction result of the twist-off torque of the torque transmission shaft is closer to a real value, and a reference is provided for the structural design of the torque transmission shaft.

Description

Technical Field

[0001] The invention belongs to the technical field of aero-engines, and in particular relates to a method and system for predicting the breaking torque of a torsion transmission shaft of an aero-engine. Background Art

[0002] The aero-engine torsion shaft is the main load-bearing part under the high-speed rotating working conditions of the engine, and is one of the key or important parts. Its main function is to support blades, impellers and other rotating parts, and to transmit torque. With the development of aero-engine structural design technology, structural design is facing some new problems while pursuing light weight, high reliability and high safety. The prediction of the torsion torque of the engine torsion shaft, as one of the important contents of the static strength design of the engine torsion shaft, is one of the important problems encountered in the structural design of the engine torsion shaft. Therefore, the study of the prediction method of the torsion torque of the engine torsion shaft is of great significance to the development of the structural design technology of the torsion shaft.

[0003] The existing method for calculating the breaking torque of the torsion transmission shaft is mainly a material mechanics method. This method assumes that under the action of monotonically increasing torque, when the local stress at any point in the structure reaches the stress at the time of destruction, the structure will be destroyed. This method assumes that when the equivalent stress at any local point in the torsion transmission shaft reaches the strength limit, the torsion transmission shaft will be destroyed and will no longer have the ability to withstand further increasing torque. The disadvantages of this method are:

[0004] 1) The yield effect of the material is not considered. When the shear stress of the torsion shaft exceeds the yield stress, its stress and strain are no longer linearly related. The actual load-bearing capacity of the torsion shaft exceeds the ideal linear elastic calculation result, which is conservative. This method is not suitable for the lightweight design requirements of modern engines.

[0005] 2) It is impossible to consider the influence of the special structure of the parts on the load-bearing capacity. Due to the special working environment, the engine torque transmission shaft may have holes on the wall of the torque transmission shaft. The special structure of the torque transmission path will reduce the load-bearing capacity of the shaft. The existing method has a large error in the analysis results of the breaking torque of the torque transmission shaft with a special structure. Summary of the invention

[0006] In view of the above problems, the present invention discloses a method for predicting the breaking torque of an aircraft engine torsion shaft, comprising:

[0007] Correct the stress-strain curve of the material according to the mechanical property measurement results of the torque transmission shaft;

[0008] Establishing a finite element model of the torque transmission shaft;

[0009] Based on the finite element model of the torsion transmission shaft, the finite element model of the torsion transmission shaft is subjected to finite element analysis using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft.

[0010] Furthermore, the stress in the stress-strain curve is corrected by the following formula:

[0011] σ 修正 =K×σ

[0012] Among them, σ 修正 is the stress after correction; K is the correction coefficient; σ is the stress before correction.

[0013] Furthermore, the correction coefficient is determined by the following formula:

[0014] K=K 0.2 ; σ≤σ 0.2 ;

[0015]

[0016] K=K b ; σ=σ b ;

[0017]

[0018] Among them, σ 0.2实测 The measured 0.2% yield strength of the torsion transmission shaft; σ 0.2 σ is the 0.2% yield strength of the material used for the torque transmission shaft; b实测 is the measured tensile strength of the torsion transmission shaft; b It is the tensile strength of the material used for the torque transmission shaft.

[0019] Furthermore, the construction steps of the stress-strain curve are as follows:

[0020] Obtain the performance parameters of the torque transmission shaft material;

[0021] determining a plurality of construction points based on the performance parameters;

[0022] Construct stress-strain curves based on construction points.

[0023] Furthermore, the performance parameters include tensile strength, 0.1% yield strength, 0.2% yield strength, elongation and elastic modulus.

[0024] Furthermore, the construction points include (0, 0), (σ 0.1 / E,σ 0.1 )、(0.002+σ 0.2 / E,σ 0.2 ), (δ / 2, σ b ) and (δ, σ b );

[0025] Among them, σ 0.1is the 0.1% yield strength; E is the elastic modulus; δ is the elongation.

[0026] Furthermore, the finite element model of the torsion transmission shaft is subjected to finite element analysis using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft, which includes the following steps:

[0027] Determine the initial torque of the torque transmission shaft;

[0028] The initial torque is used as the initial load of the torque transmission shaft finite element analysis. If the equivalent stress of the torque transmission shaft under the initial torque is less than σ b实测 , the input torque is corrected by the following formula:

[0029] T n+1 =K n ×T n ;

[0030] Among them, K n =σ b实测 / σ n ; σ n is the torque T n Equivalent stress of the torsion transmission shaft under the action of n is the nth torque acting on the torque transmission shaft; T n+1 is the n+1th torque acting on the torque transmission shaft after correction;

[0031] Determine the corrected torque T n+1 Equivalent stress σ of the dangerous section of the torsion transmission shaft under the action n+1 ; If the equivalent stress σ n+1 Less than σ b实测 , then the input torque is repeatedly corrected; if the equivalent stress σ n+1 If the set conditions are met, the iteration stops and the corrected torque T n+1 is the breaking torque of the torque transmission shaft.

[0032] Furthermore, the setting conditions are as follows:

[0033] |σ b实测 -σ n+1 |≤0.1MPa.

[0034] The present invention also discloses a system for predicting the breaking torque of an aero-engine torque transmission shaft, comprising:

[0035] A correction unit, used to correct the stress-strain curve of the material according to the measurement results of the mechanical properties of the torque transmission shaft;

[0036] Establishing a unit for establishing a finite element model of the torque transmission shaft;

[0037] The determination unit is used to perform finite element analysis on the finite element model of the torsion transmission shaft based on the finite element model of the torsion transmission shaft by using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft.

[0038] Furthermore, the correction unit is specifically used for:

[0039] Obtain the performance parameters of the torque transmission shaft material;

[0040] determining a plurality of construction points based on the performance parameters;

[0041] Construct stress-strain curves based on construction points.

[0042] Compared with the prior art, the embodiments of the present invention have at least the following advantages: the present invention takes into account the influence of the material properties of the torsion transmission shaft, while also taking into account the influence of the special structure, and can predict the torsion breaking torque of the torsion transmission shaft with a complex structure in combination with the material stress-strain curve, with an error of <5%. The predicted result of the torsion breaking torque of the torsion transmission shaft is closer to the true value, providing a reference for the structural design of the torsion transmission shaft; when the stress-strain curve of the torsion transmission shaft material cannot be obtained, the construction method of the present invention can be used for construction, providing a guarantee for the prediction of the torsion breaking torque.

[0043] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A flow chart showing a method for predicting the breaking torque of an aircraft engine torque transmission shaft according to an embodiment of the present invention is shown;

[0046] Figure 2 A schematic diagram of a stress-strain curve according to an embodiment of the present invention is shown;

[0047] Figure 3 A schematic structural diagram of a torque transmission shaft according to an embodiment of the present invention is shown;

[0048] Figure 4 A schematic diagram of a torque transmission shaft with a hole feature according to an embodiment of the present invention is shown;

[0049] Figure 5 The strain analysis result of the torque transmission shaft with hole feature according to an embodiment of the present invention is shown;

[0050] Figure 6 A schematic diagram of a stress-strain curve according to an embodiment of the present invention is shown;

[0051] Figure 7 A schematic diagram of a system for predicting the torsion-breaking torque of an aircraft engine torsion shaft according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] like Figure 1 As shown, a method for predicting the breaking torque of an aircraft engine torque transmission shaft proposed by the present invention comprises the following steps:

[0054] The stress-strain curve of the torque transmission shaft material is corrected according to the mechanical property measurement results of the torque transmission shaft; for example, the torque transmission shaft material is stainless steel, and the stress-strain curve of the material is as follows: Figure 2 The stress-strain curve before correction is shown in the figure, where the yield strength σ of the material 0.2 =980MPa, tensile strength σ b =1180MPa. The measured yield strength of the torsion shaft σ 0.2实测 =1052MPa, measured tensile strength of torsion shaft σ b实测 =1380MPa. It should be noted that Figure 2 The stress-strain curves before and after correction are schematic diagrams.

[0055] Establishing a finite element model of the torque transmission shaft; the special structure of the load-bearing section of the torque transmission shaft cannot be simplified, such as openings, etc.;

[0056] Based on the finite element model of the torsion transmission shaft, the finite element model of the torsion transmission shaft is subjected to finite element analysis using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft.

[0057] In some embodiments, before correcting the stress-strain curve of the material according to the mechanical property measurement results of the torque transmission shaft, the following steps are also included:

[0058] The mechanical properties of the torque transmission shaft are measured. The mechanical properties include the measured 0.2% yield strength σ 0.2实测 , 0.2% yield strength of the material used for the torque transmission shaft 0.2 , measured tensile strength of the torsion shaft σ b实测 And the tensile strength of the material used for the torque transmission shaft b .

[0059] Figure 2 FIG. 2 shows a schematic diagram of a stress-strain curve according to an embodiment of the present invention. The strain is kept constant, and the stress in the stress-strain curve is corrected. The corrected stress-strain curve is as follows: Figure 2 shown.

[0060] In some embodiments, the stresses in the first three stages of the stress-strain curve are corrected by the following formula:

[0061] σ 修正 =K×σ (1)

[0062] Among them, σ 修正 is the stress after correction, MPa; K is the correction coefficient; σ is the stress before correction, MPa.

[0063] In some embodiments, the correction factor is determined by the following formula:

[0064] K=K 0.2 ; σ≤σ 0.2 (2)

[0065]

[0066] K=K b ; σ=σ b (4)

[0067]

[0068] Among them, σ 0.2实测 The measured 0.2% yield strength of the torsion transmission shaft, MPa; σ 0.2 Typical value of 0.2% yield strength of the material used for the torque transmission shaft, MPa; σ b实测 is the measured tensile strength of the torsion transmission shaft, MPa; σ b Typical value of tensile strength of materials used for torque transmission shafts, MPa.

[0069] In the fourth stage of the stress-strain curve, the strain is kept constant and the stress is modified to σ b实测 .

[0070] The stress-strain curve of the torque transmission shaft material can be obtained by the following two methods:

[0071] 1) Obtained from the typical stress-strain curve of existing materials;

[0072] 2) When the stress-strain curve of the material cannot be obtained, the stress-strain curve construction step of the present invention is used to construct it.

[0073] Figure 6 FIG. 2 shows a schematic diagram of a stress-strain curve according to an embodiment of the present invention. Figure 6 As shown, in some embodiments, the construction steps of the stress-strain curve are as follows:

[0074] Obtain the performance parameters of the torque transmission shaft material;

[0075] determining a plurality of construction points based on the performance parameters;

[0076] Construct stress-strain curves based on construction points.

[0077] In some embodiments, the performance parameters include tensile strength, 0.1% yield strength, 0.2% yield strength, elongation, and elastic modulus.

[0078] In some embodiments, the construction points include ①(0,0), ②(σ 0.1 / E,σ 0.1 )、③(0.002+σ 0.2 / E,σ 0.2 )、④(δ / 2,σ b ) and ⑤(δ,σ b );

[0079] Among them, σ 0.1 is the 0.1% yield strength, MPa; E is the elastic modulus, MPa; σ 0.2 0.2% yield strength, MPa; σ b is the tensile strength, MPa; δ is the elongation. It should be noted that Figure 6 The stress-strain curves constructed in the figure are only schematic diagrams.

[0080] When the stress-strain curve of the torsion transmission shaft material cannot be obtained, the construction method of the present invention can be used to construct it, providing guarantee and convenience for the prediction of the torsion breaking torque.

[0081] In some embodiments, the finite element analysis of the finite element model of the torsion transmission shaft using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft comprises the following steps:

[0082] Determine the initial torque of the torque transmission shaft: First, use the existing material mechanics method to determine the breaking torque of the torque transmission shaft as the initial torque T of the finite element analysis. 0; The initial load is loaded in 10 steps, and each small step load is set with 10 sub-steps;

[0083] The initial torque is used as the initial load of the finite element analysis of the torsion transmission shaft. If the equivalent stress of the dangerous section of the torsion transmission shaft under the initial torque is less than σ b实测 , the input torque is corrected by the following formula:

[0084] T n+1 =K n ×T n (7)

[0085] Among them, K n =σ b实测 / σ n ; σ n is the torque T n Equivalent stress of the torsion transmission shaft under the action of n is the nth torque acting on the torque transmission shaft; T n+1 is the n+1th torque acting on the torque transmission shaft after correction;

[0086] Determine the corrected torque T n+1 Equivalent stress σ of the dangerous section of the torsion transmission shaft under the action n+1 ; If the equivalent stress σ n+1 Less than σ b实测 , then repeat the above method to correct the input torque; if the equivalent stress σ n+1 If the set conditions are met, the iteration is stopped and it is considered that the torque transmission shaft has been damaged at the dangerous section. The corrected torque T n+1 is the breaking torque of the torque transmission shaft.

[0087] In some embodiments, the setting conditions are as follows:

[0088] |σ b实测 -σ n+1 |≤0.1MPa (8).

[0089] If the torque is too large and the calculation result does not converge, take the last step convergence torque T n It is calculated again as the initial torque, and the torque transmission shaft is calculated using the above-mentioned modified iterative method to obtain the breaking torque.

[0090] The method for predicting the breaking torque of an aero-engine torsion shaft of the present invention takes into account the influence of the material properties of the torsion shaft and the influence of the special structure. It can predict the breaking torque of a torsion shaft with a complex structure in combination with the material stress-strain curve, with an error of <5%. The prediction result of the breaking torque of the torsion shaft is closer to the true value, providing a reference for the structural design of the torsion shaft.

[0091] Figure 7FIG. 1 is a schematic diagram of a system for predicting the torque of a torsion shaft of an aircraft engine according to an embodiment of the present invention. Figure 7 As shown, based on the above-mentioned aircraft engine torsion shaft breaking torque prediction method, this embodiment proposes an aircraft engine torsion shaft breaking torque prediction system, including:

[0092] A correction unit, used to correct the stress-strain curve of the material according to the measurement results of the mechanical properties of the torque transmission shaft;

[0093] Establishing a unit for establishing a finite element model of the torque transmission shaft;

[0094] The determination unit is used to perform finite element analysis on the finite element model of the torsion transmission shaft based on the finite element model of the torsion transmission shaft by using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft.

[0095] In some embodiments, the correction unit is specifically used to:

[0096] Obtain the performance parameters of the torque transmission shaft material;

[0097] determining a plurality of construction points based on the performance parameters;

[0098] Construct stress-strain curves based on construction points.

[0099] The implementation process of the functions and effects of each unit in the above system is specifically described in the implementation process of the corresponding steps in the above method, which will not be repeated here.

[0100] As for the system embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The system embodiment described above is only schematic, in which the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the scheme of the present invention. Ordinary technicians in this field can understand and implement it without paying creative work.

[0101] The present invention also proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for predicting the breaking torque of the aero-engine torsion shaft when executing the computer program.

[0102] The present invention also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned method for predicting the breaking torque of an aircraft engine torsion shaft is implemented.

[0103] The present invention also proposes a computer program product, comprising computer instructions, which, when executed by a processor, implement the above-mentioned method for predicting the breaking torque of the aero-engine torsion shaft.

[0104] In order to verify the validity and accuracy of the prediction method for the breaking torque of an aircraft engine torsion shaft of the present invention, the breaking torque of a real torsion shaft is predicted and tested.

[0105] The method for predicting the breaking torque of an aircraft engine torque transmission shaft of the present invention is used to predict the breaking torque of a spline torque transmission shaft. The structural schematic diagram of the spline torque transmission shaft is shown in FIG. Figure 3 As shown in the figure, the breaking torque of the spline torque shaft calculated by the material mechanics method is 128N·m, and the breaking torque of the spline torque shaft measured by the experiment is 157N·m. The breaking torque predicted by the method for predicting the breaking torque of the aero-engine torque shaft of the present invention is 153.3N·m. The breaking torque of the torque shaft calculated by the existing method is conservative. See Table 1 for specific data.

[0106] Table 1 Torque data of a torque transmission shaft of an engine

[0107]

[0108] The torsional moment of the torque transmission shaft predicted by this method has an accuracy of -2.4% compared with the test, which is about 16% higher than the accuracy of the existing method. Currently, this method has been successfully applied to some turboshaft / turboprop engines.

[0109] Figure 4 FIG. 1 is a schematic diagram of a torque transmission shaft with hole features according to an embodiment of the present invention. In the above embodiment, the torque transmission shaft has four holes evenly distributed in the circumferential direction of the torsion section, such as Figure 4 As shown. Figure 5 As shown, by using the method of the present invention to analyze and considering the influence of the opening on the cross-sectional bearing capacity, the breaking torque is reduced from 153.3 N·m to 101 N·m. The prior art is unable to analyze the influence of the opening on the bearing capacity, and the breaking torque is still 128 N·m, with an error of 26.7%.

[0110] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In the present invention, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine different embodiments or examples described in the present invention and features of different embodiments or examples without contradiction.

[0111] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the breaking torque of an aircraft engine torque transmission shaft, characterized in that: include: Correct the stress-strain curve of the material according to the mechanical property measurement results of the torque transmission shaft; Establishing a finite element model of the torque transmission shaft; Based on the finite element model of the torsion transmission shaft, the finite element model of the torsion transmission shaft is subjected to finite element analysis using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft.

2. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 1, characterized in that: The stress in the stress-strain curve is corrected by the following formula: s 修正 =K×σ Among them, σ 修正 is the stress after correction; K is the correction coefficient; σ is the stress before correction.

3. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 2, characterized in that: The correction factor is determined by the following formula: K=K 0.2 ;σ≤σ 0.2 ; K=K b ;s=s b ; Among them, σ 0.2 The actual measured value is the 0.2% yield strength of the torsion shaft; σ 0.2 σ is the 0.2% yield strength of the material used for the torque transmission shaft; b实测 is the measured tensile strength of the torsion transmission shaft; b It is the tensile strength of the material used for the torque transmission shaft.

4. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 1, characterized in that: The construction steps of the stress-strain curve are as follows: Obtain the performance parameters of the torque transmission shaft material; determining a plurality of construction points based on the performance parameters; Construct stress-strain curves based on construction points.

5. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 4, characterized in that: The performance parameters include tensile strength, 0.1% yield strength, 0.2% yield strength, elongation and elastic modulus.

6. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 4 or 5, characterized in that: The construction points include (0, 0), (σ 0.1 / E, σ 0.1 ), (0.002 + σ 0.2 / E, σ 0.2 ), (δ / 2, σ b ), and (δ, σ b ); Among them, σ 0.1 is the 0.1% yield strength; E is the elastic modulus; δ is the elongation.

7. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 1, characterized in that: The method of performing finite element analysis on the finite element model of the torsion transmission shaft using the modified stress-strain curve based on the finite element model of the torsion transmission shaft to determine the breaking torque of the torsion transmission shaft comprises the following steps: Determine the initial torque of the torque transmission shaft; The initial torque is used as the initial load of the torque transmission shaft finite element analysis. If the equivalent stress of the torque transmission shaft under the initial torque is less than σ b实测 , the input torque is corrected by the following formula: T n+1 =K n ×T n ; Among them, K n =σ b实测 / σ n ; σ n is the torque T n Equivalent stress of the torsion transmission shaft under the action of n is the nth torque acting on the torque transmission shaft; T n+1 is the n+1th torque acting on the torque transmission shaft after correction; Determine the corrected torque T n+1 Equivalent stress σ of the dangerous section of the torsion transmission shaft under the action n+1 ; If the equivalent stress σ n+1 Less than σ b实测 , then the input torque is repeatedly corrected; if the equivalent stress σ n+1 If the set conditions are met, the iteration stops and the corrected torque T n+1 is the breaking torque of the torque transmission shaft.

8. The method for predicting the breaking torque of the aero-engine torque transmission shaft according to claim 7, characterized in that: The setting conditions are as follows: |σ b实测 -σ n+1 |≤0.1MPa.

9. An aircraft engine torque transmission shaft breaking torque prediction system, characterized in that: include: A correction unit, used to correct the stress-strain curve of the material according to the measurement results of the mechanical properties of the torque transmission shaft; Establishing a unit for establishing a finite element model of the torque transmission shaft; The determination unit is used to perform finite element analysis on the finite element model of the torsion transmission shaft based on the finite element model of the torsion transmission shaft by using the modified stress-strain curve to determine the breaking torque of the torsion transmission shaft.

10. The aircraft engine torque transmission shaft breaking torque prediction system according to claim 9, characterized in that: The correction unit is specifically used for: Obtain the performance parameters of the torque transmission shaft material; determining a plurality of construction points based on the performance parameters; Construct stress-strain curves based on construction points.

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