Bird-impact-resistant design method for air inlet channel

Abstract

The bird-impact-resistant design method for the air inlet channel comprises the steps that S1, performance parameters of a fastener are obtained through a test; s2, establishing a fastener simulation model according to the fastener performance parameters; s3, testing to obtain material performance parameters; s4, establishing a material simulation model according to the material performance parameters; s5, performing a bird strike test to obtain plate bird strike parameters; s6, establishing a board bird strike simulation model, and obtaining unit failure criteria according to board bird strike parameters; s7, bird strike parameters of connecting pieces are obtained through a bird strike test, and the connecting pieces comprise fasteners; s8, establishing a connecting piece bird impact simulation model according to the fastener simulation model, and correcting the fastener simulation model according to the connecting piece bird impact parameters; s9, performing a bird strike test to obtain sector bird strike parameters; s10, establishing a sector bird strike simulation model, and correcting the sector bird strike simulation model according to the sector bird strike parameters; s11, obtaining air inlet bird strike parameters through a bird strike test; and S12, according to the sector bird strike simulation model, establishing an air inlet bird strike simulation model, and according to the air inlet bird strike parameters, correcting the air inlet bird strike simulation model.

Description

Technical Field

[0001] The present invention relates to the technical field of inlet design of turbofan aeroengines, and particularly relates to a method for anti-bird-strike design of an inlet. Background Art

[0002] The main function of the inlet of a turbofan aeroengine is to provide a stable and uniform air inlet flow for the engine and decelerate and pressurize the air inlet flow to ensure the stable and reliable operation of the engine during the flight of the aircraft. The inlet has functional design requirements in aspects such as anti-bird-strike, noise reduction, anti-icing, fire prevention, and ventilation and heat exchange.

[0003] When a bird strike occurs on the inlet, it will cause large deformation or damage to the surface, and even may cause the entire inlet to fall off the engine. Some important accessories such as partial anti-icing pipelines, EEC, and lubricating oil pipelines of civil aeroengines are installed inside the fan nacelle behind the inlet. If these accessories are damaged when a bird strike occurs on the inlet, it will seriously affect the normal operation of the engine or cause the engine to catch fire, resulting in serious consequences of plane crash and death. Although necessary measures (such as arranging bird repelling devices at the airport) have been taken during the operation of the aircraft to prevent bird strike accidents, the aircraft still cannot completely avoid bird strikes during flight. In the airworthiness clauses CCAR25.571(e) and FAR25.571(e), clear requirements are put forward for the anti-bird-strike performance of the aircraft: after the aircraft suffers structural damage caused by a bird impact, it must be able to successfully complete the flight. Therefore, it is necessary to carry out anti-bird-strike performance tests on the inlet of turbofan aeroengines to verify their compliance with the clauses.

[0004] Bird strike on the inlet is a highly nonlinear impact process with a high impact speed, large impact load, and strong destructiveness. The material property parameters used in the simulation analysis of bird strike, the failure criterion of finite element mesh elements for simulating material damage, the size of the finite element mesh, the structural simplification of finite element modeling, etc. all have great influences on the simulation analysis results of bird strike on the inlet. Unreasonable selection of model parameters may lead to large errors in the simulation analysis results or even incorrect simulation results. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for anti-bird-strike design of an inlet to improve the accuracy of the bird strike simulation model of the inlet.

[0006] According to an embodiment of the present invention, an anti-bird-strike design method for an air intake duct includes step S1. Obtaining performance parameters of fasteners through tests; step S2. Establishing a simulation model of the fasteners according to the performance parameters of the fasteners; step S3. Obtaining performance parameters of materials through tests; step S4. Establishing a simulation model of the materials according to the performance parameters of the materials; step S5. Obtaining bird-strike parameters of flat plates and curved plates through bird-strike tests; step S6. Establishing a bird-strike simulation model of the flat plates and curved plates, and obtaining a unit failure criterion for bird-strike simulation analysis according to the bird-strike parameters of the flat plates and curved plates; step S7. Obtaining bird-strike parameters of a connector through a bird-strike test, where the connector includes the fasteners; step S8. Establishing a bird-strike simulation model of the connector according to the simulation model of the fasteners, and correcting the simulation model of the fasteners according to the bird-strike parameters of the connector; step S9. Obtaining bird-strike parameters of an air intake duct fan section through a bird-strike test; step S10. Establishing a bird-strike simulation model of the air intake duct fan section according to the simulation model of the fasteners, the bird-strike simulation model of the connector, and the bird-strike simulation model of the flat plates and curved plates, and correcting the bird-strike simulation model of the air intake duct fan section according to the bird-strike parameters of the air intake duct fan section; step S11. Obtaining bird-strike parameters of the air intake duct through a bird-strike test; and step S12. Establishing a bird-strike simulation model of the air intake duct according to the bird-strike simulation model of the air intake duct fan section, and correcting the bird-strike simulation model of the air intake duct according to the bird-strike parameters of the air intake duct.

[0007] In one or more embodiments, step S3 includes obtaining the Young's modulus, static yield strength, and plastic hardening modulus of the material through static tensile and compression tests of the material; and obtaining the medium strain rate parameter and high strain rate parameter of the material through dynamic tensile tests of the material to obtain the yield strength of the material at different strain rates.

[0008] In one or more embodiments, step S6 includes performing bird-strike simulation analysis on the flat plates and curved plates based on the mesh size of the bird-strike simulation model of the flat plates and curved plates, comparing and analyzing the bird-strike simulation analysis results of the flat plates and curved plates with the bird-strike parameters of the flat plates and curved plates, and calibrating the unit failure criterion for bird-strike simulation analysis.

[0009] In one or more embodiments, step S6 further includes comparing and analyzing the bird-strike simulation analysis results of the flat plates and curved plates with the bird-strike parameters of the flat plates and curved plates, and calibrating the contact parameters for bird-strike simulation analysis.

[0010] In one or more embodiments, in step S6, the unit failure criterion for the metal material is equivalent plastic strain at failure.

[0011] In one or more embodiments, in step S6, the unit failure criterion for the metallic material is the stress triaxiality failure constitutive relation.

[0012] In one or more embodiments, in step S6, the unit failure criterion for the composite material is the maximum tensile and compressive strains.

[0013] In one or more embodiments, step S9 includes establishing a bird strike simulation model for the inlet fan section based on the simulation model of the fastener, the bird strike simulation model of the connecting member, and the bird strike simulation models of the flat plate and the curved plate, performing a bird strike simulation analysis on the inlet fan section to obtain the bird strike weak positions of the inlet fan section, and conducting a bird strike test on the bird strike weak positions of the inlet fan section to obtain the bird strike parameters of the inlet fan section.

[0014] In one or more embodiments, step S9 further includes verifying the compliance of the anti-bird strike performance of the inlet through the bird strike test.

[0015] In one or more embodiments, step S11 further includes verifying the compliance of the anti-bird strike performance of the inlet through the bird strike test.

[0016] The embodiments of the present invention at least have the following beneficial effects:

[0017] Conduct corresponding tests from the bottom up at the material level, component level, sub-assembly level, sub-component level, and component level. According to the test results, establish and correct the corresponding simulation sub-models, and finally obtain the bird strike simulation model of the inlet, improving the accuracy of the bird strike simulation model of the inlet, and further enhancing the reliability of the anti-bird strike design of the inlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other features, properties, and advantages of the present invention will become more apparent from the following description in conjunction with the drawings and embodiments, wherein:

[0019] Figure 1 is a perspective view of the inlet being struck by a bird;

[0020] Figure 2 is the sectional view of the inlet being struck by a bird at Figure 1 section A-A;

[0021] Figure 3 is a flowchart of the anti-bird strike design method for the inlet;

[0022] Figure 4 is a schematic diagram of the modular structure of the anti-bird strike design method for the inlet;

[0023] REFERENCE SIGNS:

[0024] 1 - lip;

[0025] 2 - Outer wall panel;

[0026] 3 - Inner wall panel;

[0027] 4 - Docking ring;

[0028] 5 - Front bulkhead;

[0029] 6 - Rear bulkhead. Detailed implementation mode

[0030] Now, reference will be made in detail to the embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is provided to explain the present invention, not to limit the present invention. In fact, it will be obvious to those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope or spirit of the present invention. For example, features shown or described as part of one embodiment can be used with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to cover these modifications and changes that fall within the scope of the appended claims and their equivalents.

[0031] It should be noted that these and subsequent other drawings are only examples, and they are not drawn under the condition of equal proportion, and should not be used to limit the actual protection scope required by the present invention.

[0032] As Figure 1 and Figure 2 shown, the air intake duct includes a lip 1, a front bulkhead 5, a rear bulkhead 6, an outer wall panel 2, an inner wall panel 3, and a docking ring 4. Among them, the lip 1, the front bulkhead 5, and the rear bulkhead 6 are the main areas for anti - bird strike of the air intake duct. Each part of the air intake duct is connected by rivets and bolts (not shown in the figure). The lip 1 is connected to the front bulkhead 5 by countersunk head rivets. The outer wall panel 2 is connected to the front bulkhead 5 and the rear bulkhead 6 by countersunk head rivets. The inner wall panel 3 is connected to the lip 1 by countersunk head Hi - Lock bolts. The inner wall panel 3 is connected to the docking ring 4 by countersunk head Hi - Lock bolts. The rear bulkhead 6 is connected to the docking ring 4 by rivets. The docking ring 4 is connected to the front mounting flange of the fan casing (not shown in the figure) by bolts.

[0033] As Figure 4 shown, the anti - bird strike design method of the air intake duct includes the material level. The material level includes Figure 3 the steps S1, S2, S3, and S4 shown.

[0034] As Figure 3As shown in the figure, the anti-bird-strike design method for the air intake duct includes step S1. Obtain the performance parameters of the fasteners through tests. The medium-strain-rate and high-strain-rate parameters of the material can be obtained through the material dynamic tensile test to obtain the failure strength of the fasteners. The tensile load and shear load of the material at high strain rates can be obtained. The material dynamic tensile test can use a material dynamic tensile testing machine and a Hopkinson bar. The fasteners can include rivets and bolts connecting the connecting lip 1, the front bulkhead 5, the rear bulkhead 6, the outer wall panel 2, the inner wall panel 3, and the docking ring 4.

[0035] As Figure 3 shown in the figure, the anti-bird-strike design method for the air intake duct further includes step S2. Establish a simulation model of the fasteners according to the performance parameters of the fasteners. Based on the failure strength of the fasteners obtained from the tests, calibrate the simplified simulation model of the fasteners applicable to bird-strike simulation analysis to characterize the tensile, shear, and extrusion failures of the fasteners, etc. This improves the authenticity of the simulation model of the fasteners.

[0036] As Figure 3 shown in the figure, the anti-bird-strike design method for the air intake duct further includes step S3. Obtain the performance parameters of the material through tests. Parameters such as the Young's modulus, static yield strength, and plastic hardening modulus of the material can be obtained through the material static tensile and compression tests. The medium-strain-rate and high-strain-rate parameters of the material can be obtained through the material dynamic tensile test to obtain the yield strength of the material at different strain rates. The material can include composite materials of the metal materials used in the air intake duct. The elastic modulus and maximum failure strain of the composite material at high strain rates can be obtained. The dynamic stress-strain curve of the metal material and the maximum failure plastic strain of the specimen-level material can be obtained. The material dynamic tensile test can use a material dynamic tensile testing machine and a Hopkinson bar.

[0037] As Figure 3 shown in the figure, the anti-bird-strike design method for the air intake duct further includes step S4. Establish a simulation model of the material according to the performance parameters of the material. Calibrate the material constitutive model based on the performance parameters of the material obtained from the tests to characterize the mechanical properties of the material. This improves the authenticity of the simulation model of the material.

[0038] As Figure 4 shown in the figure, the anti-bird-strike design method for the air intake duct further includes the component level. The component level includes Figure 3 step S5 and step S6 shown in the figure.

[0039] As Figure 3 shown in the figure, the anti-bird-strike design method for the air intake duct further includes step S5. Obtain the bird-strike parameters of the flat plate and the curved plate through bird-strike tests. The flat plate can include flat-shaped parts in the air intake duct, such as the titanium alloy flat plate of the bulkhead. The curved plate can include curved-shaped parts in the air intake duct, such as the aluminum alloy curved plate of the lip. The bird-strike tests for each flat plate and each curved plate are carried out separately.

[0040] AsFigure 3 As shown, the bird strike resistant design method for the air intake duct further includes step S6. Establish bird strike simulation models for flat plates and curved plates, and obtain the element failure criteria for bird strike simulation analysis according to the bird strike parameters of the flat plates and curved plates. The corresponding failure strain can be fitted based on the mesh size, and the mesh size suitable for bird strike simulation analysis can be selected. Based on the mesh size of the selected bird strike simulation models of the flat plates and curved plates, conduct bird strike simulation analysis on the flat plates and curved plates. Compare and analyze the bird strike simulation analysis results of the flat plates and curved plates with the bird strike parameters of the flat plates and curved plates, and calibrate the element failure criteria of the materials used for bird strike simulation analysis. The bird strike simulation tests for each flat plate and each curved plate are carried out separately, and the comparative analysis is also carried out separately. This improves the authenticity of the element failure criteria. The element failure criteria are also the element deletion criteria. The element failure criteria for metal materials can be the equivalent plastic strain at failure, and the equivalent plastic strain at failure is used to characterize the failure of metal materials. If the simulation accuracy does not meet the requirements, the element failure criteria for metal materials can also be the stress triaxiality failure constitutive model, and the stress triaxiality failure constitutive model is used to characterize the failure of metal materials to improve the simulation accuracy. The element failure criteria for composite materials can be the maximum tensile and compressive strains, and the maximum tensile and compressive strains are used to characterize the failure of composite materials. The contact parameters used for bird strike simulation analysis can also be calibrated by comparing and analyzing the bird strike simulation analysis results of the flat plates and curved plates with the bird strike parameters of the flat plates and curved plates. The contact parameters are used to simulate the contact between the bird body and the air intake duct simulation model. This improves the authenticity of the contact parameters.

[0041] As Figure 4 shown, the bird strike resistant design method for the air intake duct further includes the component level. The component level includes Figure 3 the steps S7 and S8 shown as follows.

[0042] As Figure 3 shown, the bird strike resistant design method for the air intake duct further includes step S7. Obtain the bird strike parameters of the connecting parts through bird strike tests. The connecting parts include fasteners. The connecting parts are the components at the connection points of the air intake duct, such as seams and riveted plates. The connecting parts naturally include the fasteners that connect the various parts mentioned above. Decompose the components at the connection points of the air intake duct into connecting parts such as seams and riveted plates, and conduct corresponding bird strike tests for different connecting parts.

[0043] As Figure 3 shown, the bird strike resistant design method for the air intake duct further includes step S8. According to the simulation model of the fastener, establish the bird strike simulation model of the connecting part, and correct the simulation model of the fastener according to the bird strike parameters of the connecting part. The bird strike simulation model of the connecting part can be established based on the simplified simulation model of the fastener. The bird strike simulation analysis can be carried out on the connecting part. Compare and analyze the bird strike simulation analysis results of the connecting part with the bird strike parameters of the connecting part to verify the failure mode of the connecting part. This improves the authenticity of the bird strike simulation model of the connecting part and corrects the failure strength of the simulation model of the fastener, which further improves the authenticity of the simulation model of the fastener.

[0044] As Figure 4 shown, the anti-bird-strike design method of the air intake also includes the sub-component level. The sub-component level includes Figure 3 the steps S9 and S10 shown in

[0045] As Figure 3 shown, the anti-bird-strike design method of the air intake also includes step S9. Obtain the bird-strike parameters of the air intake fan segment through bird-strike tests. The air intake fan segment is a fan-shaped unit of the air intake in the circumferential direction, and multiple air intake fan segments are circumferentially connected to form the air intake fan segment. According to the simulation models of fasteners, the bird-strike simulation models of connectors, and the bird-strike simulation models of flat plates and curved plates, establish the bird-strike simulation model of the air intake fan segment, conduct bird-strike simulation analysis on the air intake fan segment, screen the bird-strike weak positions of the air intake fan segment, and conduct bird-strike tests on the bird-strike weak positions of the air intake fan segment to obtain the bird-strike parameters of the air intake fan segment, saving the time and cost of bird-strike tests. And the compliance of the air intake's anti-bird-strike performance can be preliminarily verified through the bird-strike tests at the bird-strike weak positions of the air intake fan segment, saving time and cost.

[0046] As Figure 3 shown, the anti-bird-strike design method of the air intake also includes step S10. According to the simulation models of fasteners, the bird-strike simulation models of connectors, the bird-strike simulation models of flat plates and curved plates, establish the bird-strike simulation model of the air intake fan segment, and according to the bird-strike parameters of the air intake fan segment, correct the bird-strike simulation model of the air intake fan segment. Conduct bird-strike simulation analysis on the air intake fan segment, compare and analyze the bird-strike simulation analysis results of the air intake fan segment and the bird-strike parameters of the air intake fan segment, and accordingly correct the bird-strike simulation model of the air intake fan segment. This further improves the fidelity of the bird-strike simulation model of the air intake fan segment.

[0047] As Figure 4 shown, the anti-bird-strike design method of the air intake also includes the component level. The component level includes Figure 3 the steps S11 and S12 shown in

[0048] As Figure 3 shown, the anti-bird-strike design method of the air intake also includes step S11. Obtain the bird-strike parameters of the air intake through bird-strike tests. Bird-strike tests can be conducted on the full-scale and complete air intake to obtain the bird-strike parameters of the air intake. And the compliance of the air intake's anti-bird-strike performance can be verified through the bird-strike tests on the full-scale and complete air intake, saving time and cost.

[0049] As Figure 3As shown, the bird strike resistance design method for the air intake duct further includes step S12. According to the bird strike simulation model of the air intake duct fan segment, establish the bird strike simulation model of the air intake duct. According to the bird strike parameters of the air intake duct, correct the bird strike simulation model of the air intake duct. Conduct bird strike simulation analysis on the air intake duct, compare and analyze the bird strike simulation analysis results of the air intake duct and the bird strike parameters of the air intake duct, and accordingly correct the bird strike simulation model of the air intake duct to make the bird strike simulation analysis results of the air intake duct support the bird strike parameters of the air intake duct, further improving the authenticity of the bird strike simulation model of the air intake duct, and thus obtaining the final bird strike simulation model of the air intake duct.

[0050] As Figure 4 shown, conduct corresponding tests from bottom to top at the material level, component level, sub-assembly level, sub-component level, and component level. According to the test results, establish and correct the corresponding simulation sub-models, and finally obtain the bird strike simulation model of the air intake duct, improving the accuracy of the bird strike simulation model of the air intake duct, and further improving the reliability of the bird strike resistance design of the air intake duct. In addition, from the material level, component level, sub-assembly level, sub-component level, and component level from bottom to top, the size of the test piece and the complexity of the test scale increase gradually, and the number of test pieces decreases gradually, reducing the research and development technical risks and reducing the research and development costs.

[0051] Although the present invention is disclosed as above with embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention.

Claims

1. A method for designing an air inlet to resist bird strike, characterized in that include: Step S1. Obtaining performance parameters of the fastener through testing; Step S2. Establishing a simulation model of the fastener according to the performance parameters of the fastener; Step S3. Obtaining performance parameters of the material through experiments; Step S4. Establishing a simulation model of the material according to the performance parameters of the material; Step S5. Obtaining bird strike parameters of flat plates and curved plates through bird strike tests; Step S6. Establishing the bird strike simulation model of the flat plate and the curved plate, and obtaining the unit failure criterion for bird strike simulation analysis according to the bird strike parameters of the flat plate and the curved plate; Step S7. Obtaining bird strike parameters of the connecting member through a bird strike test, wherein the connecting member includes the fastener; Step S8. Establishing a bird strike simulation model of the connecting member according to the simulation model of the fastener, and correcting the simulation model of the fastener according to the bird strike parameters of the connecting member; Step S9. Obtaining bird strike parameters of the air inlet sector through a bird strike test; Step S10. Establishing a bird strike simulation model of the air inlet segment according to the simulation model of the fastener, the bird strike simulation model of the connector, and the bird strike simulation model of the flat plate and the curved plate, and correcting the bird strike simulation model of the air inlet segment according to the bird strike parameter of the air inlet segment; Step S11. Obtaining bird strike parameters of the air inlet through a bird strike test; as well as Step S12: establishing a bird strike simulation model of the air inlet according to the bird strike simulation model of the air inlet sector, and correcting the bird strike simulation model of the air inlet according to the bird strike parameters of the air inlet.

2. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that The step S3 comprises: Obtaining Young's modulus, static yield strength, and plastic strengthening modulus of the material through static tensile and compression tests of the material; and The medium strain rate parameters and high strain rate parameters of the material are obtained through a dynamic tensile test of the material, so as to obtain the yield strength of the material at different strain rates.

3. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that The step S6 comprises: Based on the grid size of the bird strike simulation model of the flat plate and the curved plate, a bird strike simulation analysis is performed on the flat plate and the curved plate, the bird strike simulation analysis results of the flat plate and the curved plate and the bird strike parameters of the flat plate and the curved plate are compared and analyzed, and the unit failure criterion for the bird strike simulation analysis is calibrated.

4. The method for designing an air inlet to resist bird strike according to claim 3, characterized in that The step S6 further comprises: The bird strike simulation analysis results of the flat plate and the curved plate and the bird strike parameters of the flat plate and the curved plate are compared and analyzed, and the contact parameters used for the bird strike simulation analysis are calibrated.

5. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that: In step S6, the unit failure criterion of the metal material is equivalent failure plastic strain.

6. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that: In step S6, the unit failure criterion of the metal material is a stress triaxial failure constitutive law.

7. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that: In step S6, the element failure criterion of the composite material is the maximum tensile and compressive strains.

8. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that The step S9 comprises: A bird strike simulation model of the inlet sector is established according to the simulation model of the fastener, the bird strike simulation model of the connecting part, and the bird strike simulation models of the flat plate and the curved plate. A bird strike simulation analysis is performed on the inlet sector to obtain the bird strike weak position of the inlet sector. A bird strike test is performed on the bird strike weak position of the inlet sector to obtain the bird strike parameters of the inlet sector.

9. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that The step S9 further comprises: The bird strike test is used to verify the anti-bird strike compliance of the air inlet duct.

10. The method for designing an air inlet to resist bird strike according to claim 1, characterized in that The step S11 further includes: The bird strike test is used to verify the anti-bird strike compliance of the air inlet duct.

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