Bird impact resistant design method for air intake

Abstract

A bird impact resistant design method for an air intake includes S1. testing to obtain fastener performance parameters; 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. bird impact testing to obtain panel bird impact parameters; S6. establishing a panel bird impact simulation model, and obtaining element failure criteria according to the panel bird impact parameters; S7. bird impact testing to obtain connecting piece bird impact parameters, the connecting piece including the fastener; 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. bird impact testing to obtain sector bird impact parameters; S10. establishing a sector bird impact simulation model, and correcting the sector bird impact simulation model according to the sector bird impact parameters; S11. bird impact testing to obtain air intake bird impact parameters; and S12. establishing an air intake bird impact simulation model according to the sector bird impact simulation model, and correcting the air intake bird impact simulation model according to the air intake bird impact parameters.

Description

Technical Field

[0001] This invention relates to the field of turbofan aero-engine inlet design technology, specifically to an inlet bird strike resistant design method. Background Technology

[0002] The primary function of the air intake in a turbofan aero-engine is to provide a stable and uniform airflow and to decelerate and pressurize the airflow to ensure the engine's stability and reliability during flight. The air intake is designed with functional requirements in place for bird strike resistance, noise reduction, anti-icing, fire prevention, and ventilation and heat exchange.

[0003] Bird strikes to the air intake can cause significant surface deformation or damage, and may even cause the entire air intake to detach from the engine. Critical components of civil aircraft engines, such as anti-icing lines, engine control valves (EEC), and lubrication lines, are located inside the fan nacelle behind the air intake. Damage to these components during a bird strike can severely affect engine operation or cause an engine fire, leading to catastrophic consequences such as aircraft wreckage and loss of life. Although necessary measures are taken during aircraft operation (such as installing bird deterrent devices at airports) to prevent bird strikes, it is impossible to completely avoid them during flight. Airworthiness regulations CCAR25.571(e) and FAR25.571(e) specify clear requirements for aircraft bird strike resistance: an aircraft must be able to successfully complete its flight after suffering structural damage from a bird strike. Therefore, bird strike resistance tests are necessary in the airworthiness certification of turbofan aircraft engines to verify their compliance with these regulations.

[0004] Bird strikes in air intakes are highly nonlinear impact processes characterized by high impact velocity, large impact load, and strong destructiveness. The material performance parameters used in the simulation analysis of bird strikes, the failure criteria of finite element mesh elements for simulating material failure, the size of the finite element mesh, and the simplification of the structure in the finite element model all have a significant impact on the simulation analysis results of bird strikes in air intakes. Inappropriate 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 this invention is to provide an intake duct bird strike protection design method to improve the accuracy of intake duct bird strike simulation models.

[0006] According to an embodiment of the present invention, the intake duct bird strike resistance design method includes the following steps: S1. Obtaining the performance parameters of fasteners through experiments; S2. Establishing a simulation model of the fasteners based on the performance parameters of the fasteners; S3. Obtaining the performance parameters of materials through experiments; S4. Establishing a simulation model of the materials based on the performance parameters of the materials; S5. Obtaining bird strike parameters of flat plates and curved plates through bird strike tests; S6. Establishing bird strike simulation models of the flat plates and curved plates, and obtaining unit failure criteria for bird strike simulation analysis based on the bird strike parameters of the flat plates and curved plates; S7. Obtaining bird strike parameters of connectors, including the fasteners, through bird strike tests; S8. Establishing a simulation model of the fasteners based on the simulation model of the fasteners. Step S9. Obtain the bird strike parameters of the intake duct segment through bird strike tests; Step S10. Establish the bird strike simulation model of the intake duct segment based on the bird strike simulation models of the fastener, the connector, and the flat plate and curved plate, and correct the bird strike simulation model of the intake duct segment based on the bird strike parameters of the intake duct segment; Step S11. Obtain the bird strike parameters of the intake duct through bird strike tests; and Step S12. Establish the bird strike simulation model of the intake duct based on the bird strike simulation model of the intake duct segment, and correct the bird strike simulation model of the intake duct based on the bird strike parameters of the intake duct.

[0007] In one or more embodiments, step S3 includes obtaining the Young's modulus, static yield strength, and plastic strengthening modulus of the material through static tensile and compression tests; and obtaining the medium strain rate parameter and high strain rate parameter of the material through dynamic tensile tests, so as 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 plate and curved plate based on the mesh size of the bird strike simulation model of the flat plate and curved plate, comparing and analyzing the bird strike simulation analysis results of the flat plate and curved plate with the bird strike parameters of the flat plate and curved plate, and calibrating the unit failure criteria used 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 plate and the curved plate with the bird strike parameters of the flat plate and the curved plate, and calibrating the contact parameters used for bird strike simulation analysis.

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

[0011] In one or more embodiments, in step S6, the unit failure criterion of the metallic material is a stress triaxial failure constitutive model.

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

[0013] In one or more embodiments, step S9 includes establishing a bird strike simulation model of the intake duct segment based on the simulation model of the fastener, the bird strike simulation model of the connector, and the bird strike simulation models of the flat plate and the curved plate; performing bird strike simulation analysis on the intake duct segment to obtain the bird strike weak points of the intake duct segment; and conducting bird strike tests on the bird strike weak points of the intake duct segment to obtain the bird strike parameters of the intake duct segment.

[0014] In one or more embodiments, step S9 further includes verifying the bird strike resistance of the air intake through the bird strike test.

[0015] In one or more embodiments, step S11 further includes verifying the bird strike resistance of the air intake through the bird strike test.

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

[0017] Based on the bottom-up approach of conducting tests at the material level, component level, sub-component level, and component level, and based on the test results, corresponding simulation sub-models are established and modified to finally obtain the bird strike simulation model of the air intake, thereby improving the accuracy of the bird strike simulation model of the air intake and thus improving the reliability of the bird strike resistance design of the air intake. Attached Figure Description

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

[0019] Figure 1 An oblique view of the air intake duct after being struck by a bird;

[0020] Figure 2 For the air intake to be damaged by bird strikes Figure 1 Cross-sectional view at point AA;

[0021] Figure 3 A flowchart illustrating the bird strike protection design method for air intakes;

[0022] Figure 4 A schematic diagram of a modular structure for a bird strike protection design method for an air intake;

[0023] Figure label:

[0024] 1-Lips and mouth;

[0025] 2-Exterior wall panel;

[0026] 3-Inner wall panels;

[0027] 4-Dating ring;

[0028] 5-Front partition frame;

[0029] 6-Rear partition frame. Detailed Implementation

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

[0031] It should be noted that these and other accompanying drawings are merely examples and are not drawn to scale, and should not be construed as limiting the scope of protection of the present invention.

[0032] like Figure 1 and Figure 2 As shown, the air intake 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. The lip 1, front bulkhead 5, and rear bulkhead 6 are the main areas of the air intake for bird strike protection. The various components of the air intake are connected by rivets and bolts (not shown in the figure). The lip 1 is connected to the front bulkhead 5 by countersunk rivets. The outer wall panel 2 is connected to the front bulkhead 5 and the rear bulkhead 6 by countersunk rivets. The inner wall panel 3 is connected to the lip 1 by countersunk high-strength bolts. The inner wall panel 3 is connected to the docking ring 4 by countersunk high-strength bolts. The rear bulkhead 6 is connected to the docking ring 4 by rivets. The docking ring 4 is bolted to the front mounting flange of the fan casing (not shown in the figure).

[0033] like Figure 4 As shown, the bird strike protection design method for the air intake includes the material level. The material level includes... Figure 3 Steps S1, S2, S3, and S4 are shown.

[0034] like Figure 3As shown, the air intake bird strike protection design method includes step S1. Obtaining the performance parameters of the fasteners through testing. The medium strain rate and high strain rate parameters of the material can be obtained through dynamic tensile testing to determine the failure strength of the fasteners. The tensile load and shear load of the material under high strain rate can be obtained. Dynamic tensile testing can be performed using a dynamic tensile testing machine and a Hopkinson bar. Fasteners may include rivets and bolts connecting the lip 1, front partition 5, rear partition 6, outer wall plate 2, inner wall plate 3, and mating ring 4.

[0035] like Figure 3 As shown, the intake duct bird strike protection design method also includes step S2: establishing a simulation model of the fastener based on its performance parameters. A simplified simulation model of the fastener suitable for bird strike simulation analysis can be calibrated based on the failure strength of the fastener obtained from experiments, characterizing tensile, shear, and extrusion failures of the fastener. This improves the realism of the fastener simulation model.

[0036] like Figure 3 As shown, the bird strike resistant design method for the air intake also includes step S3: obtaining the material's performance parameters through experiments. Parameters such as Young's modulus, static yield strength, and plastic strengthening modulus of the material can be obtained through static tensile and compression tests. Medium strain rate and high strain rate parameters of the material can be obtained through dynamic tensile tests to obtain the yield strength of the material at different strain rates. The material may include composite materials of the metal materials used in the air intake. 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. Dynamic tensile testing of the material can be performed using a dynamic tensile testing machine and a Hopkinson bar.

[0037] like Figure 3 As shown, the inlet bird strike protection design method also includes step S4: establishing a material simulation model based on the material's performance parameters. The material constitutive model can be calibrated based on the material's performance parameters obtained from experiments to characterize the material's mechanical properties. This improves the realism of the material simulation model.

[0038] like Figure 4 As shown, the bird strike protection design method for air intakes also includes the component level. The component level includes... Figure 3 Steps S5 and S6 are shown.

[0039] like Figure 3 As shown, the intake duct bird strike resistance design method also includes step S5: obtaining the bird strike parameters of the flat plate and the curved plate through bird strike tests. The flat plate may include flat plate-shaped parts in the intake duct, such as a titanium alloy flat plate for the bulkhead. The curved plate may include curved plate-shaped parts in the intake duct, such as an aluminum alloy curved lip plate. Bird strike tests are conducted separately for each flat plate and each curved plate.

[0040] like Figure 3 As shown, the inlet bird strike resistance design method also includes step S6: establishing bird strike simulation models for flat and curved plates, and obtaining element failure criteria for bird strike simulation analysis based on the bird strike parameters of the flat and curved plates. The corresponding failure strain can be fitted based on the mesh size. A mesh size suitable for bird strike simulation analysis can be selected. Based on the selected mesh size of the bird strike simulation model for the flat and curved plates, bird strike simulation analysis is performed on the flat and curved plates. The bird strike simulation analysis results and bird strike parameters of the flat and curved plates are compared and analyzed to calibrate the element failure criteria for the materials used in bird strike simulation analysis. Bird strike simulation tests are conducted separately for each flat and curved plate, and comparative analyses are also conducted separately. This improves the realism of the element failure criteria. The element failure criteria are also known as element deletion criteria. The element failure criteria for metallic materials can be equivalent failure plastic strain, which is used to characterize the failure of metallic materials. If the simulation accuracy does not meet the requirements, the element failure criteria for metallic materials can also be stress triaxial failure constitutive model, which is used to characterize the failure of metallic materials to improve simulation accuracy. The failure criterion for composite materials can be the maximum tensile or compressive strain, which is used to characterize composite material failure. Furthermore, by comparing and analyzing the bird strike simulation results and parameters of flat and curved plates, contact parameters used for bird strike simulation analysis can be calibrated. These contact parameters are used to simulate the contact between the bird and the air intake simulation model. This improves the realism of the contact parameters.

[0041] like Figure 4 As shown, the bird strike protection design method for air intakes also includes the component level. The component level includes... Figure 3 Steps S7 and S8 are shown.

[0042] like Figure 3 As shown, the intake duct bird strike resistance design method further includes step S7: obtaining bird strike parameters of the connectors through bird strike tests. The connectors include fasteners. The connectors are components of the intake duct at the connection point, such as seams and riveted plates. The connectors naturally include the aforementioned fasteners connecting the various parts. The components of the intake duct at the connection point are decomposed into connectors such as seams and riveted plates, and corresponding bird strike tests are performed on different connectors.

[0043] like Figure 3 As shown, the intake duct bird strike resistance design method further includes step S8: establishing a bird strike simulation model of the connector based on the fastener simulation model, and correcting the fastener simulation model based on the connector's bird strike parameters. A bird strike simulation model of the connector can be established based on a simplified fastener simulation model. Bird strike simulation analysis can be performed on the connector, and the results of the connector's bird strike simulation analysis can be compared with the connector's bird strike parameters to verify the connector's failure mode. This improves the realism of the connector's bird strike simulation model, and correcting the failure strength of the fastener simulation model further enhances the realism of the fastener simulation model.

[0044] like Figure 4 As shown, the bird strike protection design method for air intakes also includes a sub-component level. The sub-component level includes... Figure 3 Steps S9 and S10 are shown.

[0045] like Figure 3 As shown, the intake duct bird strike resistance design method also includes step S9: obtaining the bird strike parameters of the intake duct sector through bird strike tests. An intake duct sector is a fan-shaped unit in the circumferential direction of the intake duct; multiple intake duct sectors are connected circumferentially to form an intake duct sector. Based on simulation models of fasteners, bird strike simulation models of connectors, and bird strike simulation models of flat and curved plates, a bird strike simulation model of the intake duct sector can be established. Bird strike simulation analysis of the intake duct sector can be performed to identify bird strike weak points. Bird strike tests can then be conducted on these weak points to obtain the bird strike parameters of the intake duct sector, saving time and cost in bird strike testing. Furthermore, the bird strike resistance compliance of the intake duct can be preliminarily verified simultaneously through bird strike tests on the weak points of the intake duct sector, saving time and cost.

[0046] like Figure 3 As shown, the intake duct bird strike resistance design method further includes step S10. Based on the simulation models of fasteners, connectors, flat plates, and curved plates, a bird strike simulation model of the intake duct segment is established. The bird strike simulation model of the intake duct segment is then corrected based on the bird strike parameters of the intake duct segment. Bird strike simulation analysis is performed on the intake duct segment, and the results of the bird strike simulation analysis are compared with the bird strike parameters of the intake duct segment. Based on this, the bird strike simulation model of the intake duct segment is corrected. This further improves the realism of the bird strike simulation model of the intake duct segment.

[0047] like Figure 4 As shown, the bird strike protection design method for air intakes also includes the component level. The component level includes... Figure 3 Steps S11 and S12 are shown.

[0048] like Figure 3 As shown, the bird strike resistance design method for the air intake also includes step S11: obtaining the bird strike parameters of the air intake through a bird strike test. A bird strike test can be performed on a full-size, complete air intake to obtain the bird strike parameters. Furthermore, the bird strike resistance compliance of the air intake can be simultaneously verified through a full-size, complete air intake bird strike test, saving time and cost.

[0049] like Figure 3As shown, the bird strike resistance design method for the air intake also includes step S12. Based on the bird strike simulation model of the air intake sector, a bird strike simulation model of the air intake is established. Based on the bird strike parameters of the air intake, the bird strike simulation model of the air intake is corrected. Bird strike simulation analysis is performed on the air intake, and the results of the bird strike simulation analysis are compared and analyzed with the bird strike parameters of the air intake. Based on this, the bird strike simulation model of the air intake is corrected so that the results of the bird strike simulation analysis support the bird strike parameters of the air intake, further improving the realism of the bird strike simulation model of the air intake, thereby obtaining the final bird strike simulation model of the air intake.

[0050] like Figure 4 As shown, corresponding experiments are conducted from the bottom up, starting at the material level, component level, sub-component level, and final component level. Based on the experimental results, corresponding simulation sub-models are established and revised, ultimately obtaining a bird strike simulation model of the air intake. This improves the accuracy of the bird strike simulation model and thus enhances the reliability of the air intake's bird strike resistance design. Furthermore, by progressing from the material level, component level, sub-component level, and final component level, the specimen size and experimental scale complexity increase progressively, while the number of specimens decreases progressively, reducing development risks and R&D costs.

[0051] Although the present invention has been disclosed above with reference to 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 bird strike resistant design method for an air intake, characterized in that... include: Step S1. Obtain the performance parameters of the fasteners through testing; Step S2. Establish a simulation model of the fastener based on its performance parameters; Step S3. Obtain the material's performance parameters through experiments; Step S4. Establish a simulation model of the material based on its performance parameters; Step S5. Obtain bird strike parameters for flat and curved plates through bird strike tests; Step S6. Establish bird strike simulation models of the flat plate and curved plate, and obtain unit failure criteria for bird strike simulation analysis based on the bird strike parameters of the flat plate and curved plate. Step S7. Obtain the bird strike parameters of the connector, which includes the fastener, through a bird strike test; Step S8. Based on the simulation model of the fastener, establish a bird strike simulation model of the connector, and correct the simulation model of the fastener based on the bird strike parameters of the connector. Step S9. Obtain the bird strike parameters of the intake duct sector through bird strike tests; Step S10. Based on the simulation model of the fastener, the bird strike simulation model of the connector, and the bird strike simulation models of the flat plate and the curved plate, establish the bird strike simulation model of the intake duct segment, and correct the bird strike simulation model of the intake duct segment based on the bird strike parameters of the intake duct segment. Step S11. Obtain the bird strike parameters of the air intake through a bird strike test; as well as Step S12. Based on the bird strike simulation model of the intake duct sector, establish a bird strike simulation model of the intake duct, and correct the bird strike simulation model of the intake duct based on the bird strike parameters of the intake duct.

2. The bird strike duct anti-aircraft design method according to claim 1, characterized in that... Step S3 includes: The Young's modulus, static yield strength, and plasticity modulus of the material were obtained through static tensile and compression tests; and The medium strain rate parameters and high strain rate parameters of the material are obtained through dynamic tensile testing, so as to obtain the yield strength of the material at different strain rates.

3. The air intake anti-bird strike design method according to claim 1, characterized in that... Step S6 includes: Based on the mesh size of the bird strike simulation model of the flat plate and curved plate, bird strike simulation analysis is performed on the flat plate and curved plate. The bird strike simulation analysis results of the flat plate and curved plate are compared and analyzed with the bird strike parameters of the flat plate and curved plate, and the unit failure criteria used for bird strike simulation analysis are calibrated.

4. The air intake anti-bird strike design method according to claim 3, characterized in that... Step S6 further includes: By comparing and analyzing the bird strike simulation analysis results of the flat plate and the curved plate with the bird strike parameters of the flat plate and the curved plate, the contact parameters used for bird strike simulation analysis are calibrated.

5. The air intake anti-bird strike design method according to claim 1, characterized in that: In step S6, the unit failure criterion for the metallic material is the equivalent failure plastic strain.

6. The bird strike duct anti-aircraft design method according to claim 1, characterized in that: In step S6, the unit failure criterion for the metallic material is a stress triaxial failure constitutive model.

7. The air intake anti-bird strike design method according to claim 1, characterized in that: In step S6, the failure criterion for the unit of the composite material is the maximum tensile and compressive strain.

8. The bird strike duct anti-aircraft design method according to claim 1, characterized in that... Step S9 includes: Based on the simulation models of the fasteners, the bird strike simulation models of the connectors, and the bird strike simulation models of the flat plate and curved plate, a bird strike simulation model of the intake duct segment is established. Bird strike simulation analysis is performed on the intake duct segment to obtain the bird strike weak points of the intake duct segment. Bird strike tests are conducted on the bird strike weak points of the intake duct segment to obtain the bird strike parameters of the intake duct segment.

9. The bird strike duct anti-aircraft design method according to claim 1, characterized in that... Step S9 further includes: The bird strike test was used to verify the bird strike resistance of the air intake.

10. The bird strike duct anti-bird strike design method according to claim 1, characterized in that... Step S11 further includes: The bird strike test was used to verify the bird strike resistance of the air intake.

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