Dynamic modeling analysis method for main reduction supporting rod type liquid elastic vibration isolation system

Abstract

The invention provides a dynamic modeling analysis method for a main reduction supporting rod type liquid elastic vibration isolation system, the main reduction supporting rod type liquid elastic vibration isolation system is formed by connecting a liquid elastic vibration isolator into a main reduction supporting rod in series, and the method comprises the following steps: analyzing transmission characteristics in a vertical direction; analyzing transmission characteristics of independent action of torque in a rotor rotation plane; analyzing the transmission characteristics of the combined action of the force and the torque in the rotating plane of the rotor; according to modeling, analysis and comparison of a liquid elastic vibration isolator equation in calculation of vibration isolation characteristics in the vertical direction and the horizontal direction of the vibration isolation system, it can be seen that internal stress and motion deformation of the vibration isolator are consistent for different external stress forms or vibration isolation system construction forms. Motion deformation and stress of all internal parts are inherent characteristics of the vibration isolator and are not affected by external conditions, and vibration reduction of a vibration isolation system is only related to the design of the liquid elastic vibration isolator.

Description

Technical Field

[0001] The present application belongs to the technical field of helicopter vibration control, and in particular relates to a dynamic modeling and analysis method for a main strut-type liquid-elastic vibration isolation system. Background Art

[0002] Liquid-elastic vibration isolators utilize the principle of dynamic anti-resonance. On the one hand, they have greater static stiffness, and on the other hand, they have higher vibration isolation efficiency at the isolation frequency point. However, liquid-elastic vibration isolators can only isolate vibration loads along the axial direction of the vibration isolator.

[0003] Taking advantage of the characteristic of helicopter main struts transmitting axial loads, the liquid-elastic vibration isolator is connected in series to the main struts to form a liquid-elastic vibration isolation system. However, how to achieve the vibration reduction function of the installed liquid-elastic vibration isolation system and how to achieve the motion correlation between the vibration isolation system and the vibration isolator require reliable dynamic modeling technology to support the design of the liquid-elastic vibration isolation system. Summary of the invention

[0004] Purpose of the invention: To establish a modeling method for a liquid-elastic vibration isolation system suitable for a main-reducing strut type machine. This method parameterizes the main-reducing strut installation angle, the main-reducing fuselage connection stiffness and the liquid-elastic vibration isolator, finds out the transfer characteristics of the liquid-elastic vibration isolation system, and realizes the analysis of the addition of main-reducing struts to the liquid-elastic vibration isolation system from the perspective of vibration reduction, which can greatly meet the engineering design needs of the liquid-elastic vibration isolation system modified machine.

[0005] The present application provides a method for dynamic modeling and analysis of a main strut type liquid-elastic vibration isolation system, wherein the main strut type liquid-elastic vibration isolation system is formed by connecting a liquid-elastic vibration isolator in series to the main strut, and the method comprises the following steps:

[0006] Analyze the transfer characteristics in the vertical direction;

[0007] Analyze the transfer characteristics of the torque acting alone in the rotor's rotating plane;

[0008] Analyze the transmission characteristics of the combined forces and moments within the rotor's rotating plane.

[0009] Preferably, the analyzing the transfer characteristics in the vertical direction includes:

[0010] Mass force analysis of the main reducer and rotor system;

[0011] Analysis of the mass and force of the fuselage;

[0012] Model each component of the liquid-elastic vibration isolator separately and perform force analysis;

[0013] Based on all the above analysis, the natural frequency of vertical vibration of the vibration isolation system can be obtained. The force transmission rate of the vibration isolation system is defined as the amplitude ratio of input and output forces. According to the principles of mechanics, the transmission rate can be obtained.

[0014] Preferably, the mass force analysis of the main reducer and the rotor system includes:

[0015] To M 1 Force analysis:

[0016]

[0017] In formula (1), f is the exciting force, f 1 is the force of the support rod on the main reducer, f 2 is the force exerted by the strut on the fuselage, M 1 represents the mass of the main reducer and rotor system, u represents the vertical displacement of the main reducer, and α is the vertical angle between the vibration isolation system strut and the fuselage.

[0018] 4. The method according to claim 3, characterized in that the force analysis of the mass of the fuselage part comprises:

[0019] To M 2 Force analysis:

[0020]

[0021] In formula (2), f 2 is the force exerted by the strut on the fuselage, M 2 represents the mass of the fuselage, and v represents the vertical displacement of the fuselage.

[0022] Preferably, the modeling of each component of the liquid-elastic vibration isolator and the force analysis include:

[0023]

[0024] K in formula (3) 2 is the volume compensation spring stiffness, m is the mass of the liquid in the inertial channel, K 1 is the stiffness of the main rubber spring of the vibration isolator, p 1 is the upper chamber pressure, p 2 is the pressure of the lower chamber, c is the liquid damping, and the displacement of the upper liquid chamber is x 1 , the displacement of the lower liquid chamber is x 2 , the displacement generated by compensation is x d , the displacement of the channel liquid flow is x 0 , A 2 is the area of ​​the upper liquid chamber, A 1 is the area of ​​the lower liquid chamber, A 0 is the channel area, m 1 is the main reduction mass shared, m 2 To share the quality of the fuselage.

[0025] Preferably, the analysis of the transfer characteristics of the torque acting alone in the rotor rotation plane includes:

[0026] The influence of the forces and moments in the rotor's rotating plane on the fuselage mainly causes the fuselage's angle response and the fuselage's acceleration response in the horizontal plane;

[0027] When only the moment M(t) acts in the rotor rotation plane, the angular response characteristics of the vibration isolation system are the same as those of the focusing system;

[0028] c θ = 0, the fuselage angle response amplitude θ can be obtained 20 for:

[0029]

[0030] In the formula

[0031]

[0032] Let the determinant be zero, that is, det(K-ω 2 M)=0, the natural frequency of the focused vibration isolation system can be solved as:

[0033]

[0034] Since the focused vibration isolation system mainly isolates the vibration load in the rotor rotation plane, and the load in this direction mainly causes the angular response of the fuselage, the ratio of the torque transmitted to the fuselage to the amplitude of the excitation torque is used in the selection of the transmission rate, which can be solved as follows:

[0035]

[0036] Preferably, the analysis of the transfer characteristics of the combined force and torque in the rotor rotation plane includes:

[0037] Under the action of internal forces in the rotating plane, the vibration isolation system will have a small range of horizontal displacement, which makes it impossible for the axes of the struts to intersect at one point in space. That is, the vibration isolation system does not have focusing characteristics at this time.

[0038] When considering unidirectional force and moment, the moment of the rotor rotating plane load on the rotation center of the main reducer rigid body is:

[0039] M(t)=F(t)(p+h z -h Ω )+M Ω (t) (8)

[0040] In space, the elongation of the strut due to the rigid body motion of the fuselage is:

[0041] Δl 12 =[v x (t)sinα+r B θ2y (t)]cosθ

[0042] Δl 22 =[v x (t)sinα+r B θ 2y (t)]sinθ

[0043] Δl 32 =-[v x (t)sinα+r B θ 2y (t)]cosθ

[0044] Δl 42 =-[v x (t)sinα+r B θ 2y (t)]sinθ (9)

[0045] Vibration load in the rotating plane F(t) = F 0 e jwt ,M(t)=M y e jwt , then the exciting torque on the main reducer generated by the vibration load is

[0046] M 0 (t) = F (t) (p + h z -h Ω )+M y (t) = [F 0 (p+h z -h Ω )+M y ]e jwt (10)

[0047] The transmissibility is taken as the ratio of the torque transmitted to the fuselage to the amplitude of the input equivalent torque. The equivalent torque is the sum of the torque of the rotating plane force on the center of mass B of the fuselage and the excitation torque. The transmissibility is

[0048]

[0049] Preferably, the method further comprises:

[0050] By comparing the vertical and horizontal vibration isolation characteristics of the vibration isolation system, it can be seen that for different external force forms or vibration isolation system construction forms, the internal force and motion deformation of the vibration isolator are consistent. The motion deformation and force of the internal components are inherent characteristics of the vibration isolator and are not affected by external conditions.

[0051] Beneficial technical effects of this application:

[0052] According to the modeling analysis and comparison of the liquid-elastic vibration isolator equation in the calculation of the vertical and horizontal vibration isolation characteristics of the vibration isolation system, it can be seen that for different external force forms or vibration isolation system construction forms, the internal force and motion deformation of the vibration isolator are consistent. The motion deformation and force of the internal components are inherent characteristics of the vibration isolator and are not affected by external conditions. The vibration reduction of the vibration isolation system is only related to the design of the liquid-elastic vibration isolator.

[0053] The vertical motion deformation of the vibration isolation system only considers the vertical displacement degree of freedom, and the vertical motion is only affected by the vibration isolator; the horizontal motion deformation includes two degrees of freedom: horizontal displacement and horizontal deflection, and is jointly affected by the vibration isolator and the main reducer bottom spring. The transmissibility curve of the vibration isolation system in the rotor rotation plane is relative to the vertical direction, increasing the interaction between the displacement and angle degrees of freedom. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a force diagram of the liquid vibration isolator provided in an embodiment of the present application;

[0055] Figure 2 is a schematic diagram of a focused liquid-elastic vibration isolation system provided in an embodiment of the present application;

[0056] Figure 3 It is a schematic diagram of a vibration isolation system under the action of internal forces in a rotating plane provided in an embodiment of the present application;

[0057] Figure 4 It is a schematic diagram of the angular response mechanical model of the vibration isolation system provided in the embodiment of the present application;

[0058] Figure 5 It is a schematic diagram of the main reducer and fuselage rigid body motion provided in an embodiment of the present application;

[0059] Figure 6 It is a schematic diagram of the forces acting on the liquid isolator of the vibration isolation system under the action of unidirectional force and moment provided in the embodiment of the present application. DETAILED DESCRIPTION

[0060] The liquid-elastic vibration isolation system in this scheme combines the characteristics of liquid-elastic vibration isolators isolating axial loads and helicopter main struts transmitting axial loads and easily achieving focusing. A liquid-elastic vibration isolation system modeling method suitable for the installation of helicopter main struts is proposed. This method realizes the joint modeling of the liquid-elastic vibration isolation device design and the main strut structure installation parameters.

[0061] See also Figure 1-Figure 6 ,Will Figure 1 The liquid-elastic vibration isolator in the focusing system is connected in series to form a focusing liquid-elastic vibration isolation system, such as Figure 2 shown.

[0062] 1. Transfer characteristics in the vertical direction

[0063] To M 1 Force analysis:

[0064]

[0065] In formula (1), f is the exciting force, f 1 is the force of the support rod on the main reducer, f 2 is the force exerted by the strut on the fuselage, M 1 represents the mass of the main reducer and rotor system, u represents the vertical displacement of the main reducer, and α is the vertical angle between the vibration isolation system strut and the fuselage.

[0066] To M 2 Force analysis:

[0067]

[0068] In formula (2), f 2 is the force exerted by the strut on the fuselage, M 2 represents the mass of the fuselage, and v represents the vertical displacement of the fuselage.

[0069] The components of the liquid-elastic vibration isolator in the vibration isolation system are modeled separately, and the force analysis is as follows:

[0070]

[0071] K in formula (3) 2 is the volume compensation spring stiffness, m is the mass of the liquid in the inertial channel, K 1 is the stiffness of the main rubber spring of the vibration isolator, p 1 is the upper chamber pressure, p 2 is the pressure of the lower chamber, c is the liquid damping, and the displacement of the upper liquid chamber is x 1 , the displacement of the lower liquid chamber is x 2 , the displacement generated by compensation is x d , the displacement of the channel liquid flow is x 0 , A 2 is the area of ​​the upper liquid chamber, A 1 is the area of ​​the lower liquid chamber, A 0 is the channel area, m 1 is the main reduction mass shared, m 2 To share the quality of the fuselage.

[0072] Let q = [uvx 0 x d p 1 p 2 ] T , combining equation 1, equation 2 and the force analysis of the liquid-elastic vibration isolator to form the following equation:

[0073]

[0074] In the above formula

[0075]

[0076] Take the periodic exciting force f = f 0 e jwt , then under the action of periodic excitation, each component can be regarded as periodic motion, that is,

[0077]

[0078] Then Equation 3 can be written as

[0079] (-Mω 2 +iωC+K)q=F (6)

[0080] The vertical vibration natural frequency f of the vibration isolation system can be obtained 0 for

[0081]

[0082] The force transmission rate of the vibration isolation system is defined as the amplitude ratio of the input and output forces. According to the principles of mechanics, the transmission rate is

[0083]

[0084] The transmissibility can be solved

[0085]

[0086] In the formula

[0087] A=4M 2 cos 2 α(mw 2 A 0 A 1 A 2 2 -A 1 2 mw 2 A 2 2 +A 1 2 A 0 2 K 2 +A 0 2 A 2 2 K 1 );

[0088] B=4M 2 cos 2 α(wcA 12 TO 2 2 +ηA 0 2 TO 2 2 K 1 );

[0089] C=A 2 2 [4mcos 2 α(A 1 -TO 0 ) 2 (M 2 +4m 2 body 2 α)+(4m 1 body 2 α+M 1 )

[0090] (4A 0 2 m 2 body 2 α+4A 1 2 mcos 2 α+A 0 2 M 2 )];

[0091] D=16cA 1 TO 2 2 body 4 α(-m 2 TO 1 +2A 0 m 2 +A 1 mm 1 TO 1 )-4cA 1 TO 2 2 body 2 α(M 1 TO 1 -M 2 TO 1 +2A 0 M 2 );

[0092] E=-4A 0 2 body 2 α[A 2 2 K 1 (1+iη)+A 1 2K 2 ][4cos 2 α(m+m 1 +m 2 )+M 1 +M 2 ];

[0093] 2. Rotor rotation plane

[0094] The forces and moments in the rotor rotation plane will cause the fuselage angle response on the one hand, and the fuselage acceleration response on the other hand. Under the load in the rotor rotation plane, the vibration isolation system is subjected to the following forces: Figure 3 As shown, 1, 2, 3, and 4 in the figure represent four struts with liquid-elastic vibration isolators in series, which are arranged in a focusing manner; M 1 is the mass of the main reducer and rotor system, M 2 is the mass of the fuselage system, f is the rotor exciting force; x is the x-direction of the fuselage coordinate, the origin is the center of mass of the fuselage, along the longitudinal direction of the fuselage, α is the installation angle of the strut, that is, the angle between the strut and the vertical direction of the fuselage, θ is the angle between the projection of the strut along the horizontal plane of the fuselage and the x-direction; f 11 、f 12 1 rod vs. M 1 、M 2 The force, f 21 、f 22 2 rods vs. M 1 、M 2 The force, f 31 、f 32 3 rods vs. M 1 、M 2 The force, f 41 、f 42 4-pole vs. M 1 、M 2 The force of action.

[0095] When the internal force in the rotor rotation plane is zero, the axes of the struts in the vibration isolation system intersect at a certain point in space. At this time, the vibration isolation system has an obvious focusing characteristic for the moment vibration isolation effect in the rotor rotation plane; when the internal force in the rotation plane is not zero, the vibration isolation system will produce horizontal deformation under the action of the force, and the system will no longer have a focusing characteristic. The following will model and analyze these two states respectively.

[0096] (1) The torque in the rotor rotation plane acts alone

[0097] The influence of the forces and moments in the rotor rotation plane on the fuselage mainly causes the fuselage angle response and the acceleration response in the horizontal plane of the fuselage. When only the moment M(t) in the rotor rotation plane acts, the angular response characteristics of the vibration isolation system are the same as the angular response of the focusing system. Figure 4 shown.

[0098] c θ = 0, the fuselage angle response amplitude θ can be obtained 20 for:

[0099]

[0100] In the formula

[0101]

[0102] Among them, F 0 represents the excitation force amplitude, M0 represents the excitation torque amplitude, J 1 is the moment of inertia of the rotor and main reducer system about the center of mass, J 2 is the moment of inertia of the fuselage about its center of mass.

[0103] Let the determinant be zero, that is, det(K-ω 2 M)=0, the natural frequency of the focused vibration isolation system can be solved as:

[0104]

[0105] Since the focused vibration isolation system mainly isolates the vibration load in the rotor rotation plane, and the load in this direction mainly causes the angular response of the fuselage, the ratio of the torque transmitted to the fuselage to the amplitude of the excitation torque is used in the selection of the transmission rate, which can be solved as follows:

[0106]

[0107] Where M out and M in They represent the amplitude of the torque transmitted to the fuselage and the excitation torque respectively.

[0108] (2) The forces and moments in the rotor's rotating plane act together

[0109] The forces and moments in the rotating plane of the rotor will cause the fuselage to respond at an angle. For the focused vibration isolation system, under the action of the forces and moments in the rotating plane, when the angle response is small, the rotor and the main reducer rotate around the virtual focus; while for the focused liquid-elastic vibration isolation system in this patent, since it is elastic in all directions, under the action of the forces in the rotating plane, the vibration isolation system will have a small range of horizontal displacement, resulting in the inability of the axes of the struts to intersect at one point in space, that is, the vibration isolation system at this time does not have a focusing characteristic.

[0110] Figure 5 This is a schematic diagram of the vibration isolation system being subjected to the internal forces in the rotor rotation plane. In the figure, the connection points of the struts are distributed on a circle. For the rotor and main reducer system, the diameter of the connection point distribution circle is d u ; For the fuselage, the diameter of the connection point distribution circle is d wThe bottom end of the main reducer is connected to the fuselage through a spring damping system.

[0111] When considering unidirectional force and moment, the vibration isolation system is subjected to Figure 4 The moment of the rotor rotating plane load on the main reducer rigid body rotation center is:

[0112] M(t)=F(t)(p+h z -h Ω )+M Ω (t) (8)

[0113] In the formula, h Ω h is the vertical distance from point C to the hinge point plane, z It is the vertical distance from the center of mass A of the main reduction system to the plane of the hinge point.

[0114] In space, the elongation of the strut due to the rigid body motion of the fuselage is:

[0115] Δl 12 =[v x (t)sinα+r B θ 2y (t)]cosθ

[0116] Δl 22 =[v x (t)sinα+r B θ 2y (t)]sinθ

[0117] Δl 32 =-[v x (t)sinα+r B θ 2y (t)]cosθ

[0118] Δl 42 =-[v x (t)sinα+r B θ 2y (t)]sinθ (9)

[0119] In the formula, θ 2y is the fuselage angle response; A is the center of mass of the main reducer, B is the center of mass of the fuselage, and C is the rotation center of the main reducer rigid body; the distance from point C to the main reducer hinge point is r C , the vertical distance to the elastic connection point with the machine is h C ; The distance from point B to each connection point of the fuselage is the same, set to r B ; The vertical distance from point B to the plane of the fuselage connection point is recorded as h B ; γ 1 For r B The angle between the strut axis and the strut axis is taken as an acute angle, γ 2 For rB and the angle between the plane of the fuselage hinge point.

[0120] By comparing the vertical and horizontal vibration isolation characteristics of the vibration isolation system, it can be seen that for different external force forms or vibration isolation system structures, the internal force and motion deformation of the vibration isolator are consistent. The motion deformation and force of the internal components are inherent characteristics of the vibration isolator and are not affected by external conditions.

[0121] Vibration load in the rotating plane F(t) = F 0 e jwt ,M(t)=M y e jwt , then the exciting torque on the main reducer generated by the vibration load is

[0122] M 0 (t) = F (t) (p + h z -h Ω )+M y (t) = [F 0 (p+h z -h Ω )+M y ]e jwt (10)

[0123] The transmissibility is taken as the ratio of the torque transmitted to the fuselage to the amplitude of the input equivalent torque. The equivalent torque is the sum of the torque of the force in the rotating plane on the center of mass B of the fuselage and the excitation torque. Then the transmissibility is

[0124]

[0125] According to the modeling analysis and comparison of the liquid-elastic vibration isolator equation in the calculation of the vertical and horizontal vibration isolation characteristics of the vibration isolation system, it can be seen that for different external force forms or vibration isolation system construction forms, the internal force and motion deformation of the vibration isolator are consistent. The motion deformation and force of the internal components are inherent characteristics of the vibration isolator and are not affected by external conditions. The vibration reduction of the vibration isolation system is only related to the design of the liquid-elastic vibration isolator.

[0126] The vertical motion deformation of the vibration isolation system only considers the vertical displacement degree of freedom, and the vertical motion is only affected by the vibration isolator; the horizontal motion deformation includes two degrees of freedom: horizontal displacement and horizontal deflection, and is jointly affected by the vibration isolator and the main reducer bottom spring. The transmissibility curve of the vibration isolation system in the rotor rotation plane is relative to the vertical direction, increasing the interaction between the displacement and angle degrees of freedom.

Claims

1. A dynamic modeling and analysis method for a main strut type liquid-elastic vibration isolation system, characterized in that: The liquid-elastic vibration isolation system is formed by connecting the liquid-elastic vibration isolator in series to the main strut, and the method comprises the following steps: Analyze the transmission characteristics of the coupling system between the liquid-elastic vibration isolation system and the body system in the vertical direction; Analyze the transmission characteristics of the coupling system of the liquid-elastic vibration isolation system and the body system when the torque acts alone in the rotor rotation plane; The transmission characteristics of the coupling system of the liquid-elastic vibration isolation system and the body system under the combined action of force and torque in the rotor rotation plane are analyzed.

2. The method according to claim 1, characterized in that The analyzing the transfer characteristics of the coupling system between the liquid-elastic vibration isolation system and the body system in the vertical direction includes: Mass force analysis of the main reducer and rotor system; Analysis of the mass and force of the fuselage; Model each component of the liquid-elastic vibration isolator separately and perform force analysis; Based on all the above analysis, the natural frequency of vertical vibration of the vibration isolation system can be obtained. The force transmission rate of the vibration isolation system is defined as the amplitude ratio of input and output forces. According to the principles of mechanics, the transmission rate can be obtained.

3. The method according to claim 2, characterized in that The mass force analysis of the main reducer and the rotor system includes: Force analysis of M1: In formula (1), f is the exciting force, f1 is the force of the strut on the main reducer, f2 is the force of the strut on the fuselage, M1 represents the mass of the main reducer and rotor system, u represents the vertical displacement of the main reducer, and α is the vertical angle between the strut of the vibration isolation system and the fuselage.

4. The method according to claim 3, characterized in that The force analysis of the fuselage mass includes: Stress analysis of M2: In formula (2), f2 is the force exerted by the strut on the fuselage, M2 is the mass of the fuselage, and v is the vertical displacement of the fuselage.

5. The method according to claim 4, characterized in that The components of the liquid-elastic vibration isolator are modeled and subjected to force analysis, including: In formula (3), K2 is the volume compensation spring stiffness, m is the mass of the liquid in the inertial channel, K1 is the stiffness of the main rubber spring of the vibration isolator, p1 is the pressure of the upper chamber, p2 is the pressure of the lower chamber, c is the liquid damping, the displacement generated by the upper liquid chamber is x1, the displacement generated by the lower liquid chamber is x2, and the displacement generated by the compensation is x d , the liquid flow displacement of the channel is x0, A2 is the area of ​​the upper liquid cavity, A1 is the area of ​​the lower liquid cavity, A0 is the channel area, m1 is the shared main reduction mass, and m2 is the shared fuselage mass.

6. The method according to claim 5, characterized in that The analysis of the transmission characteristics of the coupling system of the liquid-elastic vibration isolation system and the body system under the action of torque alone in the rotor rotation plane includes: The influence of the forces and moments in the rotor's rotating plane on the fuselage mainly causes the fuselage's angle response and the fuselage's acceleration response in the horizontal plane; When only the moment M(t) acts in the rotor rotation plane, the angular response characteristics of the vibration isolation system are the same as those of the focusing system; c θ = 0, the fuselage angle response amplitude θ can be obtained 20 for: In the formula Let the determinant be zero, that is, det(K-ω 2 M)=0, the natural frequency of the focused vibration isolation system can be solved as: Since the focused vibration isolation system mainly isolates the vibration load in the rotor rotation plane, and the load in this direction mainly causes the angular response of the fuselage, the ratio of the torque transmitted to the fuselage to the amplitude of the excitation torque is used in the selection of the transmission rate, which can be solved as follows:

7. The method according to claim 6, characterized in that The analysis of the transmission characteristics of the coupling system of the liquid-elastic vibration isolation system and the body system under the combined action of force and torque in the rotor rotation plane includes: Under the action of internal forces in the rotating plane, the vibration isolation system will have a small range of horizontal displacement, which makes it impossible for the axes of the struts to intersect at one point in space. That is, the vibration isolation system does not have focusing characteristics at this time. When considering unidirectional force and moment, the moment of the rotor rotating plane load on the rotation center of the main reducer rigid body is: M(t)=F(t)(p+h z -h Ω )+M Ω (t) (8) In space, the elongation of the strut due to the rigid body motion of the fuselage is: Δl 12 =[v x (t)sinα+r B i 2y (t)]cosθ Δl 22 =[v x (t)sinα+r B i 2y (t)]sinθ Δl 32 =-[v x (t)sinα+r B i 2y (t)]cosθ Δl 42 =-[v x (t)sinα+r B i 2y (t)]sinθ (9) Vibration load in the rotating plane F(t) = F0e jwt ,M(t)=M y e jwt , then the exciting torque on the main reducer generated by the vibration load is M0(t)=F(t)(p+h z -h Ω )+M y (t)=[F0(p+h z -h Ω )+M y ]e jwt (10) The transmissibility is taken as the ratio of the torque transmitted to the fuselage to the amplitude of the input equivalent torque. The equivalent torque is the sum of the torque of the rotating plane force on the center of mass B of the fuselage and the excitation torque. The transmissibility is 8. The method according to claim 7, characterized in that The method further comprises: By comparing the vertical and horizontal vibration isolation characteristics of the vibration isolation system, it can be seen that for different external force forms or vibration isolation system construction forms, the internal force and motion deformation of the vibration isolator are consistent. The motion deformation and force of the internal components are inherent characteristics of the vibration isolator and are not affected by external conditions.

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