Rapid evaluation method for coupling stability frequency design of helicopter rotor body

Abstract

The invention belongs to the technical field of helicopter dynamics design, and discloses a rapid evaluation method for helicopter rotor body coupling stability frequency design, and the method comprises the steps: obtaining a resonance center rotating speed and a rotating speed stability margin based on the change relation of a rotor system characteristic frequency and a body modal frequency along with the rotor rotating speed; according to the method, the rotor body coupling stability is rapidly evaluated, whether the rotating speed stability margin meets the design requirement or not is determined according to the rapid evaluation result, optimization design of the rotor system characteristic frequency and the body modal frequency is carried out, and it can be ensured that the rotor body coupling stability meets the design requirement at the initial stage of design. According to the method, the problem of coupling stability of the rotorcraft body is avoided, frequency design can be more accurately carried out in each stage of model design, and the method has very high universality and engineering application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of helicopter dynamics design, and in particular relates to a rapid evaluation method for the frequency design of helicopter rotor-body coupling stability. Background Art

[0002] Helicopter rotors with spherically flexible hubs—designed to be shimmy-soft—may experience rotor-airframe coupling stability issues. The coupling between the rotor system and the helicopter can cause vibrations to persist, amplify, and even diverge, significantly impacting helicopter vibrations. The essence of the rotor-airframe coupling stability issue lies in the coupling of the rotor shimmy's retreating frequency with the airframe mode at the hub center within the rotational plane. The two systems mutually excite each other. When the system damping is insufficient, this exacerbates the rotor shimmy motion and the airframe's motion on the landing gear, a phenomenon known as ground resonance. When a ground-operating helicopter experiences an initial external disturbance, the rotor blades shimmy in a retreating pattern, generating unbalanced centrifugal forces that excite airframe vibrations on the landing gear. The hub center, as a point on the airframe, vibrates along with the airframe. However, as the fundamental connection point of the rotor system, the hub center's vibrations, in turn, contribute to the rotor's motion within the rotational plane through base excitation, affecting (exacerbating or weakening) the inherent vibrations of the individual blades. If the vibration characteristics of these two vibration systems satisfy a specific relationship: the frequency of the centrifugal exciting force generated by the swing of the rotor system is the same as or close to a certain order natural vibration frequency of the entire aircraft on the landing gear, and the vibration mode corresponding to this order natural frequency can cause the center of the hub to vibrate in the rotation plane, and at the same time, the work consumed by the damping of the blade damper and the landing gear system in one vibration cycle is less than the work done by the above-mentioned exciting force on the system, then the swing motion of the blade and the vibration of the entire aircraft on the landing gear will aggravate each other, forming a vicious cycle, and within a few seconds the amplitude can be large enough to destroy the helicopter.

[0003] The inherent condition for the occurrence of rotor and fuselage coupling stability problems is that the damping of the blade damper and the landing gear system is large enough, or the frequency of the centrifugal excitation force generated by the rotor system's swing is far enough away from the vibration frequency of the entire aircraft on the landing gear. Then, the vibrations excited by the external interference of the above two vibration systems will weaken each other until they disappear, and the ground resonance problem will not occur.

[0004] Therefore, in the early stage of design, the key to avoiding the rotor-body coupling stability problem is to reasonably configure the relationship between the rotor system's swing-back mode and the fuselage mode.

[0005] The traditional method is to use the overall parameters and preliminary performance parameters of the landing gear to calculate the ground resonance stability curve in the early stage of design, which lacks a relatively intuitive optimization design link; in the engineering design stage, the hub center dynamic characteristics test is carried out using the test prototype to obtain the modal parameters of the fuselage on the landing gear, and then the ground resonance stability curve is calculated. Since the prototype has been completed in trial production, the optimization design cycle is long and the cost is high.

[0006] This invention uses a rapid evaluation method for rotor-airframe coupled stability frequency design on a specific helicopter to conduct rotor-airframe coupled stability design. Experimental verification demonstrates that this method's accuracy meets engineering requirements. It has high engineering value in analyzing rotor-airframe coupled stability, troubleshooting stability issues, and developing stability control plans for new aircraft. Summary of the Invention

[0007] Aiming at the problem of rotor-body coupling stability, the present invention proposes a rapid evaluation method for the frequency design of helicopter rotor-body coupling stability. Based on the relationship between the rotor system characteristic frequency and the body modal frequency and the rotor speed, the resonance center speed and the speed stability margin are obtained, and the rotor-body coupling stability is rapidly evaluated. Based on the result of the rapid evaluation, it is determined whether the speed stability margin meets the design requirements. In this way, the optimization design of the rotor system characteristic frequency and the body modal frequency is carried out, and it can be ensured that the rotor-body coupling stability meets the design requirements in the early design stage.

[0008] The technical solution of the present invention is achieved as follows:

[0009] In a first aspect, the present invention discloses a method for rapid evaluation of frequency design of helicopter rotor-body coupled stability, comprising the following steps:

[0010] Step 1: Obtain the parameters of the rotor system;

[0011] Step 2: Calculate the rotor system shimmy retreat frequency at different rotor speeds using the above parameters;

[0012] Step 3: Use the full aircraft model to calculate the four modal frequencies of the body on the landing gear;

[0013] Step 4: Draw a speed-frequency graph, including: plotting the variation of the shimmy-backward frequency with the rotor speed, plotting the variation of the four airframe modal frequencies with the rotor speed, plotting the vertical line corresponding to the rated rotor speed, and plotting the vertical line corresponding to the speed stability margin requirement;

[0014] Step 5: Determine the resonance center, which is the intersection of the shimmy backward frequency curve and the four body modal frequency curves;

[0015] Step 6: Determine whether the resonance center falls within the range defined by the speed stability margin vertical line. If not, the evaluation is qualified.

[0016] Step 7: If yes, the evaluation fails and frequency optimization design is required. Repeat steps 1-6 until the design requirements are met.

[0017] As a further solution of the present invention: the parameters of the rotor system include the rated speed of the rotor, the mass static moment of a blade, the rotational inertia of a blade, the hydraulic damper swing elastic line stiffness, the distance from the hub center to the swing hinge, and the distance from the swing hinge to the swing damper.

[0018] As a further solution of the present invention: Step 2 specifically includes the following steps:

[0019] Step 21: Convert the rotor system hydraulic damper shimmy elastic linear stiffness to shimmy angular stiffness. The specific calculation formula is as follows:

[0020] ;

[0021] in, represents the shimmy angular stiffness, ; represents the elastic linear stiffness of the hydraulic shimmy damper, ; Indicates the distance from the shimmy hinge to the shimmy damper. ;

[0022] Step 22: According to the above swing angle stiffness , and other rotor system parameters, calculate the rotor system shimmy retreat frequency at different rotor speeds. The specific calculation formula is as follows:

[0023] ;

[0024] in, represents the first-order oscillation retreat frequency, ; Indicates the distance from the hub center to the swing hinge, ; represents the mass moment of a blade about its hinge, ; represents the moment of inertia of a blade about its flap hinge, ; represents the rotor speed frequency, The specific calculation formula is as follows:

[0025] ;

[0026] in, Indicates the rotor speed, .

[0027] As a further solution of the present invention: Step 3 is specifically: calculating the mode of the body on the landing gear according to the full maneuverability characteristic model, and obtaining the frequency of the body on the landing gear, including the first-order heading frequency, the first-order lateral frequency, the second-order heading frequency, and the second-order lateral frequency.

[0028] As a further solution of the present invention: whether the design requirements are met can also be determined by:

[0029] According to the frequency-speed diagram obtained in step 4, the resonance center speed is obtained;

[0030] The speed stability margin is calculated through the resonance center speed. The specific calculation formula is as follows:

[0031] ;

[0032] in, Indicates the speed stability margin; represents the resonance center speed, ; Indicates the rated rotor speed, ;

[0033] Determine whether the speed stability margin meets the requirements. The judgment conditions are as follows:

[0034] When the speed stability margin is greater than 15%, the design requirements are met and the evaluation ends;

[0035] When the speed stability margin is less than or equal to 15%, it does not meet the design requirements and frequency optimization design is required.

[0036] As a further solution of the present invention: the frequency optimization design specifically includes the following steps:

[0037] Step 71: Optimize one or more parameters such as the shimmy elastic line stiffness of the rotor system hydraulic shimmy damper, the distance from the shimmy hinge to the shimmy damper, the distance from the hub center to the shimmy hinge, the mass static moment and the rotational inertia of the blade around the shimmy hinge, and change the shimmy backward frequency of the rotor system;

[0038] Step 72: Optimize the design of parameters such as the improved landing gear stiffness and the body elastic stiffness to change the body modal frequency.

[0039] In a second aspect, the present invention discloses an electronic device, comprising: a processor and a memory storing a computer program, wherein when the processor runs the computer program, the steps of the above-mentioned rapid evaluation method are executed.

[0040] In a third aspect, the present invention discloses a computer storage medium storing a computer program, which, when executed by a processor, performs the steps of the above-mentioned rapid evaluation method.

[0041] The beneficial effects of the present invention are:

[0042] 1. This invention uses rotor parameters and simulated airframe modal frequency parameters as inputs during the initial stages of helicopter design. From a frequency design perspective, it rapidly assesses the resonance center between the rotor shimmy frequency and the airframe modal frequency, thereby determining the ground resonance speed margin. To ensure the safety of helicopter ground tests and flights, frequency design analysis methods can be used to eliminate the possibility of ground resonance in the early stages of design. This effectively guides the design and determines the limit values ​​of rotor parameters and adjustable parameters that affect airframe frequency, eliminating the possibility of ground resonance at this early stage.

[0043] 2. The present invention identifies the influencing parameters of the mutual coupling between the rotor system and the fuselage structure, and explains the mechanism, key factors and effective solutions of the mutual coupling, thereby effectively guiding the design. In the past, the rotor-body coupling oscillation retreat frequency could only be estimated after a series of tests such as the hub center dynamic characteristics test and the landing gear static compression characteristics test were carried out. This took a long time and was costly, making it difficult to change the design or take stability control measures. Compared with traditional methods, the design method proposed in the present invention can quickly and accurately predict the rotor-body coupling oscillation retreat frequency in the early stages of design. The input parameter operation is also simpler and easier, and it can more realistically simulate the actual situation, forming a rapid evaluation and analysis method for helicopter rotor-body coupling calculations. It has high engineering value in design work such as ground resonance and tail rotor and tail boom coupling stability. Understanding the rotor-body coupling stability in the early stages of model development and formulating a stability control plan are of great significance to ensuring the flight safety of the helicopter. The present invention forms an evaluation method to achieve the purpose of avoiding the risk of rotor-body coupling stability at various development stages of the model.

[0044] 3. Relevant application examples show that according to the scheme of the present invention, a frequency design method that meets the requirements of engineering precision can be obtained, ensuring the safety requirements of rotor-body coupling stability, providing an accurate and reliable calculation method for rotor-body coupling stability design, and being able to carry out frequency design more accurately at all stages of model design. It has high universality and engineering application value.

[0045] The present invention will be described in further detail below with reference to the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic flow chart of a rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to the present invention;

[0047] Figure 2 A schematic diagram of rotational speed-frequency before optimization using a rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to the present invention;

[0048] Figure 3 The figure is a rotational speed-frequency diagram after optimization using a rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to the present invention. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Throughout the drawings, identical or similar reference numerals represent identical or similar elements or elements having identical or similar functions. The described embodiments are only some, not all, of the embodiments of the present invention.

[0050] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0051] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0052] The following is combined with Figure 1-3 The embodiments of the present invention are described in detail.

[0053] Example 1

[0054] The present invention discloses a rapid evaluation method for frequency design of helicopter rotor-body coupled stability, which comprises the following steps:

[0055] Step 1: Provide parameters of the rotor system; the parameters of the rotor system include the rated rotor speed, blade radius, mass static moment of a blade, moment of inertia of a blade, shimmy elastic linear stiffness of the hydraulic damper, distance from hub center to shimmy hinge, and distance from shimmy hinge to shimmy damper.

[0056] Step 2: Calculate the rotor characteristic frequency; specifically, the following steps are included:

[0057] Step 21: Convert the rotor system hydraulic damper shimmy elastic linear stiffness to shimmy angular stiffness. The specific calculation formula is as follows:

[0058] ;

[0059] in, represents the shimmy angular stiffness, ; represents the elastic linear stiffness of the hydraulic shimmy damper, ; Indicates the distance from the shimmy hinge to the shimmy damper. ;

[0060] Step 22: According to the above swing angle stiffness , and other rotor system parameters, calculate the rotor system shimmy retreat frequency at different rotor speeds. The specific calculation formula is as follows:

[0061] ;

[0062] in, represents the first-order oscillation retreat frequency, ; Indicates the distance from the hub center to the swing hinge, ; represents the mass moment of a blade about its hinge, ; represents the moment of inertia of a blade about its flap hinge, ; represents the rotor speed frequency, The specific calculation formula is as follows:

[0063] ;

[0064] in, Indicates the rotor speed, , is the measured value, rotor speed frequency and rotor speed Positive correlation, when the rotor speed Different values ​​are used to calculate different rotor system swing-back frequency. .

[0065] Step 3: Provide the body modal frequency; specifically:

[0066] The modal of the aircraft on the landing gear is calculated according to the full maneuverability characteristic model, and the frequency of the aircraft on the landing gear is obtained, including the first-order heading frequency, the first-order lateral frequency, the second-order heading frequency, and the second-order lateral frequency.

[0067] Step 4: Draw a speed-frequency graph; specifically, the following steps are included:

[0068] Step 41: Using the rotor shimmy backward frequency obtained in step 2, plot a curve showing the shimmy backward frequency versus rotor speed.

[0069] Step 42: Using the four airframe modal frequencies obtained in step 3, plot curves showing how the four airframe modal frequencies vary with rotor speed.

[0070] Step 43: Draw a vertical line corresponding to the rated rotor speed;

[0071] Step 44: Draw a vertical line corresponding to the speed stability margin requirement.

[0072] Step 5: Determine the resonance center; specifically:

[0073] According to the frequency-speed diagram obtained in step 4, the intersection of the shimmy backward frequency curve and the four body modal frequency curves is obtained, which is the resonance center.

[0074] Step 6: Determine the speed stability margin; specifically, the following steps are included:

[0075] Step 61: Based on the resonance center obtained in step 5, the speed stability margin is calculated using the resonance center speed. The specific calculation formula is as follows:

[0076] ;

[0077] in, Indicates the speed stability margin; represents the resonance center speed, ; Indicates the rated rotor speed, ;

[0078] Step 62: Determine whether the speed stability margin meets the requirements. The determination conditions are as follows:

[0079] When the speed stability margin is greater than 15% (the speed stability margin is the set value, which is set according to the specific design requirements), the design requirements are met and the evaluation ends;

[0080] When the speed stability margin is less than or equal to 15%, it does not meet the design requirements and frequency optimization design is required.

[0081] Another understanding of the judgment condition: combined with the attached Figure 2 If any of the four intersection points (resonance centers) falls within the speed stability margin, the design requirements will not be met. Figure 3 , if all four intersection points (resonance centers) fall outside the speed stability margin range, the design requirements are met.

[0082] Step 7: If the requirements are not met, perform frequency optimization design and repeat steps 1-6 until the speed stability margin meets the design requirements.

[0083] The frequency optimization design specifically includes the following steps:

[0084] Step 71: Optimize one or more parameters such as the shimmy elastic line stiffness of the rotor system hydraulic shimmy damper, the distance from the shimmy hinge to the shimmy damper, the distance from the hub center to the shimmy hinge, the mass static moment and the rotational inertia of the blade around the shimmy hinge, and change the shimmy backward frequency of the rotor system;

[0085] Step 72: Optimize the design of parameters such as the improved landing gear stiffness and the body elastic stiffness to change the body modal frequency.

[0086] Example 2

[0087] In order to prove the applicability and effectiveness of the present invention, the present invention is applied to design the rotor-body coupling stability frequency of a certain type of helicopter to prove the effectiveness of the rapid evaluation method of the present invention.

[0088] The present invention provides a method for quickly evaluating the frequency design of the coupled stability of a helicopter rotor body. Figure 1 , as follows:

[0089] S1: Provide the parameters of a certain type of helicopter rotor system

[0090] The parameters of the rotor system include the rated rotor speed , blade radius r, mass moment of a blade about the shimmying hinge , the moment of inertia of a blade , hydraulic damper shimmy elastic linear stiffness , Distance from hub center to swing hinge , Distance from swing hinge to swing damper The following table shows the example results of the following parameters:

[0091] symbol dimension Design value Remark #timg# #timg# 1000 Rated operating speed #timg# #timg# 0.2 Distance from hub center to flap hinge #timg# #timg# 0.15 Distance from oscillation hinge to oscillation damper #timg# #timg# 8.0 Mass static moment of blade about shimmy hinge #timg# #timg# 7.5 The moment of inertia of the blade about the flap hinge #timg# #timg# 1100 Elastic linear stiffness of shimmy damper

[0092] S2: Calculate rotor characteristic frequency

[0093] S21: Convert the rotor system hydraulic damper shimmy elastic linear stiffness to shimmy angular stiffness. The specific calculation formula is as follows:

[0094] ;

[0095] in, represents the shimmy angular stiffness, ; represents the elastic linear stiffness of the hydraulic shimmy damper, ; Indicates the distance from the shimmy hinge to the shimmy damper. ;

[0096] S22: The swing angular stiffness calculated above , and other rotor system parameters, calculate the rotor system shimmy retreat frequency at different rotor speeds. The specific calculation formula is as follows:

[0097] ;

[0098] in, represents the first-order oscillation retreat frequency, ; Indicates the distance from the hub center to the swing hinge, ; represents the mass moment of a blade about its hinge, ; represents the moment of inertia of a blade about its flap hinge, ; represents the rotor speed frequency, The specific calculation formula is as follows:

[0099] ;

[0100] in, Indicates the rotor speed, , is the measured value, rotor speed frequency and rotor speed Positive correlation, when the rotor speed Different values ​​are used to calculate different rotor system swing-back frequency. In this embodiment, the rotor speed The value is 1000 .

[0101] S3: Provide the modal parameters of a certain type of helicopter

[0102] The modal shape of the helicopter body on the landing gear is calculated based on the full maneuverability model, and the frequency of the helicopter body on the landing gear is obtained, including the first-order frequency in the heading direction, the second-order frequency in the heading direction, and the first-order frequency in the lateral direction, and the second-order frequency in the lateral direction. The results are shown in the following table:

[0103] Modal Name Lateral first order Navigation level 1 Lateral second order Heading Level 2 Frequency / Hz 5.62 6.03 6.30 7.24

[0104] S4: Draw a speed-frequency graph

[0105] S41: Using the rotor shimmy backward frequency obtained in S2, plot a curve of the shimmy backward frequency versus rotor speed;

[0106] S42: Using the airframe modal frequency from S3, plot the curve of the airframe modal frequency versus rotor speed.

[0107] S43: Draw a vertical line corresponding to the rated rotor speed;

[0108] S44: Draw the vertical line corresponding to the speed stability margin requirement.

[0109] The speed-frequency diagram obtained is shown in Figure 2 .

[0110] S5: Determine the resonance center

[0111] According to the frequency-speed diagram obtained by S4, the intersection of the swing-back frequency curve and the body modal frequency curve is obtained, which is the resonance center. Its speed is 1078 .

[0112] S6: Determine the speed stability margin

[0113] S61: The resonance center speed is 1078 according to S5 , the speed stability margin is calculated to be 7.8%, and the specific calculation formula is as follows:

[0114] ;

[0115] in, Indicates the speed stability margin; represents the resonance center speed, ; Indicates the rated rotor speed, ;

[0116] S62: Determine whether the speed stability margin does not meet the design requirements. The judgment conditions are as follows:

[0117] When the speed stability margin is greater than 15%, the design requirements are met and the evaluation ends;

[0118] When the speed stability margin is less than or equal to 15%, it does not meet the design requirements and frequency optimization design is required.

[0119] S7: Frequency Optimized Design

[0120] S71: Optimize the design of the rotor system hydraulic damper shimmy elastic line stiffness and increase the rotor system hydraulic damper shimmy elastic line stiffness to 1200 ;

[0121] S72: Optimize the design of parameters such as the improved landing gear stiffness and airframe elastic stiffness, and increase the lowest-order airframe modal frequency (the lowest of the first-order and second-order heading frequencies and the first-order and second-order lateral frequencies) to 5.65 Hz.

[0122] S8: Conclusion

[0123] Repeat steps S1 to S6 until the speed stability margin after frequency optimization design meets the design requirements.

[0124] The rapid evaluation method for frequency design obtained by applying the present invention has an accuracy that meets engineering requirements and can be applied to the rapid evaluation of helicopter rotor-body coupling frequency design.

[0125] Example 3

[0126] The present invention provides an electronic device comprising: a processor and a memory storing a computer program. In practical applications, the number of processors may be one or more, and the number of memories may be one or more. When the processor executes the computer program, the rapid evaluation method applied to the electronic device is implemented.

[0127] The memory may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory may include read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), ferromagnetic random access memory (FRAM), flash memory, magnetic surface memory, optical disk, or compact disc read-only memory (CD-ROM); magnetic surface memory may include magnetic disk memory or magnetic tape memory. Volatile memory may include random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), synchronous static random access memory (SSRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus random access memory (DRRAM).

[0128] The memory of the present invention is used to store various types of data to support the operation of the electronic device. Examples of these data include: any computer program for operating on the electronic device, such as an operating system and an application; contact data; phone book data; messages; pictures; videos, etc. Among them, the operating system includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., which are used to implement various basic services and process hardware-based tasks. The application program can include various applications, such as a media player (Media Player), a browser (Browser), etc., which are used to implement various application services. Here, the program that implements the method of the embodiment of the present invention can be included in the application program.

[0129] Example 4

[0130] The present invention also provides a computer storage medium storing a computer program. The computer storage medium may be a memory such as a ferromagnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface mount memory, an optical disc, or a compact disc read-only memory (CD-ROM); or various devices including one or any combination of the above memories, such as a mobile phone, a computer, a tablet device, a personal digital assistant, etc. When the computer program stored in the computer storage medium is executed by a processor, the rapid evaluation method applied to the above electronic device is implemented.

[0131] So far, the purpose of the present invention has been accomplished.

[0132] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rapid evaluation method for frequency design of helicopter rotor-body coupled stability, characterized by: The following steps are involved: Step 1: Obtain the parameters of the rotor system; Step 2: Use the above parameters to calculate the rotor system shimmy retreat frequency at different rotor speeds, specifically: Converting the elastic linear stiffness of the hydraulic damper of the rotor system into the angular stiffness of the shimmy : ； in, represents the shimmy angular stiffness, ; represents the elastic linear stiffness of the hydraulic shimmy damper, ; Indicates the distance from the shimmy hinge to the shimmy damper. ; According to the above swing angle stiffness , and other rotor system parameters, calculate the rotor system shimmy retreat frequency at different rotor speeds, specifically: ； in, represents the first-order oscillation retreat frequency, ; Indicates the distance from the hub center to the swing hinge, ; represents the mass moment of a blade about its hinge, ; represents the moment of inertia of a blade about its flap hinge, ; represents the rotor speed frequency, , the specific calculation formula is: ;in, Indicates the rotor speed, ; Step 3: Use the full aircraft model to calculate the four modal frequencies of the body on the landing gear; Step 4: Draw a speed-frequency graph, including: plotting the variation of the shimmy-backward frequency with the rotor speed, plotting the variation of the four airframe modal frequencies with the rotor speed, plotting the vertical line corresponding to the rated rotor speed, and plotting the vertical line corresponding to the speed stability margin requirement; Step 5: Determine the resonance center, which is the intersection of the shimmy backward frequency curve and the four body modal frequency curves; Step 6: Determine whether the resonance center falls within the range defined by the speed stability margin vertical line. If not, the evaluation is qualified. Step 7: If yes, the evaluation fails and frequency optimization design is required. Repeat steps 1-6 until the design requirements are met.

2. A rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to claim 1, characterized in that: The parameters of the rotor system include the rated speed of the rotor, the mass static moment of a blade, the rotational inertia of a blade, the shimmy elastic line stiffness of the hydraulic damper, the distance from the hub center to the shimmy hinge, and the distance from the shimmy hinge to the shimmy damper.

3. The rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to claim 1, characterized in that: The step 3 specifically includes: calculating the mode of the body on the landing gear according to the full maneuverability characteristic model, and obtaining the frequency of the body on the landing gear, including the first-order heading frequency, the first-order lateral frequency, the second-order heading frequency, and the second-order lateral frequency.

4. The rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to claim 1, characterized in that: Whether the design requirements are met can also be determined by: According to the frequency-speed diagram obtained in step 4, the resonance center speed is obtained; The speed stability margin is calculated through the resonance center speed. The specific calculation formula is as follows: ； in, Indicates the speed stability margin; represents the resonance center speed, ; Indicates the rated rotor speed, ; Determine whether the speed stability margin meets the requirements. The judgment conditions are as follows: When the speed stability margin is greater than 15%, the design requirements are met and the evaluation ends; When the speed stability margin is less than or equal to 15%, it does not meet the design requirements and frequency optimization design is required.

5. A rapid evaluation method for frequency design of helicopter rotor-body coupling stability according to claim 4, characterized in that: The frequency optimization design specifically includes the following steps: Step 71: Optimize the design of the rotor system hydraulic shimmy damper shimmy elastic linear stiffness, the distance from the shimmy hinge to the shimmy damper, the distance from the hub center to the shimmy hinge, the mass static moment and rotational inertia of the blade around the shimmy hinge, and change the rotor system shimmy backward frequency. Step 72: Optimize the design of the improved landing gear stiffness and airframe elastic stiffness parameters to change the airframe modal frequency.

6. An electronic device, characterized in that: include: A processor and a memory storing a computer program, wherein when the processor runs the computer program, the rapid assessment method according to any one of claims 1 to 5 is implemented.

7. A computer storage medium, characterized in that A computer program is stored, and when the computer program is executed by a processor, the rapid evaluation method according to any one of claims 1 to 5 is implemented.

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