Helicopter blade embedded vibration absorption device based on branch circuit

Abstract

The invention provides a helicopter blade embedded type vibration absorption device based on a branch circuit. The helicopter blade embedded type vibration absorption device comprises a shimmy folding connecting piece (1), a flapping folding connecting piece (3), a blade insert (4), a piezoelectric plate (5), a permanent magnet (7), an electromagnetic coil (9), an electromagnetic coil connecting shaft (11) and a linear bearing (12). The vibration damper is used for a helicopter in a complex vibration environment, and has the advantages of small additional mass, simple structure, multiple vibration damping directions, obvious vibration damping effect and the like. In addition, the embedded vibration absorption device is mounted in the paddle, and is convenient to mount, dismount and maintain.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopter rotor vibration reduction, and particularly relates to a helicopter blade embedded vibration absorption device based on a branch circuit. BACKGROUND

[0002] The rotor is the main lift source of the helicopter, and the blades thereof operate in an unsteady and highly unstable aerodynamic environment, which generates relatively large vibration, and further causes the helicopter to generate severe vibration, thereby affecting the safety and reliability of the helicopter, so that the development of the helicopter is limited compared with the fixed-wing aircraft. In recent years, with the development of the helicopter technology, reducing the vibration level of the helicopter has become one of the main research directions. Since the rotor is the main vibration source of the helicopter, reducing the excitation force of the rotor is an ideal target of the vibration reduction research. However, due to the complexity of the rotor dynamics and the limitation of the structural design, the rotor is difficult to achieve a very good vibration level only through the structural design, so the rotor vibration reduction technology research is carried out.

[0003] At present, the rotor vibration reduction technology can be divided into passive and active types, wherein the active vibration reduction technology includes high-order harmonic control technology, independent blade control technology, trailing edge flap vibration control technology and active torsional rotor vibration reduction technology, etc.; the passive vibration reduction technology includes a pendulum and a vibration absorber. Since the vibration absorber can suppress the rotor vibration at a low level, it has a great development prospect. Although different configurations of the vibration absorber all follow the dynamic vibration absorption principle, their vibration absorption characteristics and specific implementation principles are different. The vibration characteristics of each force element of different rotors are also different, so a good vibration absorption design scheme must be tailored according to the vibration response characteristics of the rotor. SUMMARY

[0004] OBJECTIVE The present application solves the defects of the existing blade vibration absorption device, such as large weight, complex structure, single vibration absorption direction, narrow vibration absorption frequency, sensitive vibration absorption frequency and poor vibration absorption effect, and designs a helicopter blade embedded vibration absorption device based on a branch circuit, which has the advantages of small additional mass, simple structure, multiple vibration reduction directions and obvious vibration reduction effect in a complex vibration environment. In addition, the embedded vibration absorption device is installed inside the blade, and is convenient to install, disassemble and maintain.

[0005] The application provides a helicopter blade embedded vibration absorption device based on a branch circuit, which comprises a swing vibration folding connecting piece 1, a flap vibration folding connecting piece 3, a blade inlaying piece 4, a piezoelectric sheet 5, a permanent magnet 7, an electromagnetic coil 9, an electromagnetic coil connecting shaft 11 and a linear bearing 12. The two flap vibration folding connecting pieces 3 are arranged in parallel along the span direction of the blade, and are connected to the inside of the blade through the blade inlaying piece 4 at both ends. The middle groove of the flap folding connecting piece 3 near the trailing edge of the blade is internally fixedly connected with a permanent magnet 7; the middle groove of the flap folding connecting piece 3 near the leading edge of the blade is internally fixedly connected with a linear bearing 12; an electromagnetic coil connecting shaft 11 is slidably arranged in the linear bearing 12; The electromagnetic coil 9 is sleeved on the first end of the electromagnetic coil connecting shaft 11 and is located between the two flap folding connecting pieces 3; the electromagnetic coil 9 is connected with a first circuit board; The second end of the electromagnetic coil connecting shaft 11 is connected with the first end of the pitch and roll folding connecting piece 1, and the second end of the pitch and roll folding connecting piece 1 is connected with the inside of the leading edge of the blade through a blade inlay 4; At least one piezoelectric sheet 5 is arranged on the pitch and roll folding connecting piece 1 and / or the flap folding connecting piece 3, and each piezoelectric sheet 5 is connected with a second circuit board; Each circuit board comprises a capacitor and a resistor, and the resonant frequency of the circuit board is determined according to the vibration absorption frequency; or each circuit board comprises a power supply, a capacitor and a resistor, and a negative resistance and capacitance type and a negative impedance type electromagnetic branch circuit is formed to realize vibration absorption.

[0006] Optionally, a flap frequency modulation counterweight 8 is arranged on the flap folding connecting piece 3 for adjusting the vibration absorption frequency.

[0007] Optionally, a pitch frequency modulation counterweight 10 is sleeved on the electromagnetic coil connecting shaft 11 and is located on the side of the pitch and roll folding connecting piece 1 facing the electromagnetic coil 9; The pitch frequency modulation counterweight 10 is used for adjusting the vibration absorption frequency.

[0008] Optionally, a leading edge pitch limiting block 13 is arranged at the second end of the electromagnetic coil connecting shaft 11 for limiting the movement distance of the electromagnetic coil 9 towards the permanent magnet 7.

[0009] Optionally, the electromagnetic coil 9 is threadedly connected with the electromagnetic coil connecting shaft 11.

[0010] Optionally, the permanent magnet 7 is provided with a permanent magnet cover plate 6 near the upper surface of the blade.

[0011] Optionally, a boss is arranged inside the electromagnetic coil 9 near the trailing edge side of the blade and is opposite to the boss of the electromagnetic coil connecting shaft 11, and the pitch frequency modulation counterweight 10 and the nut are connected through the nut near the leading edge side of the blade.

[0012] Optionally, the pitch frequency modulation counterweight 10 is provided with a groove near the position of the shaft center for placing the nut, so as to ensure that the nut is embedded in the groove.

[0013] Optionally, the permanent magnet 7 is made of a material with strong magnetism, and the magnetization direction is the thickness direction, i.e. the chord direction of the blade.

[0014] Optionally, the circuit board is close to the leading edge of the blade, so that the center of gravity of the blade is moved before the pitch axis of the blade.

[0015] Advantages: An embedded vibration absorbing device for helicopter blades based on a branch circuit is designed by using an electromagnetic coil, a permanent magnet, a piezoelectric sheet, a folded beam and a circuit board.

[0016] The present application solves the following problems: 1) The traditional vibration absorbing device has the disadvantages of complex structure and heavy weight. The vibration absorbing device not only has simple structure, light weight and small space occupation, but also is embedded in the blade, does not damage the aerodynamic surface of the blade and does not affect the structural load capacity, and has little influence on the rotor system; 2) Compared with the traditional vibration absorbing device, the vibration absorbing device can absorb more directions of vibration, and can absorb the vibration of the blade in the swing, waving and blade span directions; 3) The device increases the limiting device and is embedded in the blade. When the vibration absorbing device fails or is damaged, it will not cause damage to the rotor itself or increase the vibration, and the structure is more reliable; 4) The embedded vibration absorbing device has few parts, high reliability, and has a corresponding installation and maintenance opening on the upper surface of the blade, which is simple to install and easy to maintain; 5) The embedded vibration absorbing device has two modes for vibration reduction. When there is no power supply, there is a resistor in the branch circuit, thereby changing the equivalent damping of the system, (a second-order resonance circuit composed of a resistor and a capacitor is used to realize an electronic vibration absorber similar to anti-resonance) so that the frequency of the circuit board is consistent with the vibration absorbing frequency. Therefore, when the electromagnetic coil moves at the corresponding frequency, the energy in the entire circuit is dissipated fastest, so that the kinetic energy of the entire system is converted into heat energy. When there is power supply, the corresponding circuit board is designed to provide corresponding negative damping or negative capacitance, which breaks the dependence of the vibration control bandwidth on the resonance frequency of the circuit, and can be applied to non-contact wideband vibration control of continuous structures. The problem of narrow vibration absorbing frequency of passive damping is solved.

[0017] 6) Reasonably use the folded beam structure, which can not only ensure that it has a large carrying capacity in the effective direction, but also reduce the stiffness in the vibration reduction direction, so that the required frequency adjustment counterweight is lighter; 7) The vibration absorbing device adjusts the vibration absorbing frequency by changing the parameters of the electromagnetic coil, the piezoelectric sheet and the resistance / capacitance in the circuit board. In addition, the device increases the frequency adjustment counterweight (different sizes and different weights) to effectively change the vibration absorbing frequency; 8) The whole system mainly includes an electromagnetic body-permanent magnet and a closed circuit composed of a branch circuit connected in parallel with the electromagnetic coil. Reasonably designing the branch circuit can significantly increase the electromagnetic damping, thereby realizing the vibration control of the structure; 9) The device uses electromagnetic, piezoelectric sheet to form corresponding branch circuit for vibration absorption; 10) The paddle vibration absorption device converts kinetic energy into heat energy. The paddle rotates at high speed in the air, and the heat energy is dissipated (better heat dissipation effect), and the corresponding vibration absorption effect will be better. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Overall effect diagram of the helicopter paddle vibration absorption device based on branch circuit; Figure 2 Electromagnetic coil end related component installation connection diagram; Figure 3 Permanent magnet end related component installation connection diagram; Figure 4 Flap folding connecting piece diagram; Figure 5 Permanent magnet cover plate diagram; Figure 6 Circuit board diagram; Figure 7 Paddle inlay piece diagram; Figure 8 Electromagnetic coil diagram; Figure 9 Linear bearing diagram; Figure 10 Front edge swing limiting block diagram; Figure 11 Electromagnetic coil connecting shaft diagram; Figure 12a Swing folding connecting piece diagram Figure 1 ; Figure 12b Swing folding connecting piece diagram Figure 2 ; Figure 13 Flap frequency modulation counterweight diagram; Figure 14 Swing frequency modulation counterweight diagram; Figure 15 Electromagnetic coil connecting shaft and related component connection diagram; BRIEF DESCRIPTION OF DRAWINGS: 1 - swing folding connecting piece, 2 - battery and circuit board, 3 - flap folding connecting piece, 4 - paddle inlay piece, 5 - piezoelectric sheet, 6 - permanent magnet cover plate, 7 - permanent magnet, 8 - flap frequency modulation counterweight, 9 - electromagnetic coil, 10 - swing frequency modulation counterweight, 11 - electromagnetic coil connecting shaft, 12 - linear bearing, 13 - front edge swing limiting block. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] like Figures 1-15 As shown, the present invention provides a helicopter rotor blade embedded vibration absorption device based on a branch circuit, comprising: a oscillation folding connector 1, a circuit board 2, a flapping folding connector 3, a rotor blade insert 4, a piezoelectric sheet 5, a permanent magnet cover plate 6, a permanent magnet 7, a flapping frequency tuning counterweight 8, an electromagnetic coil 9, an oscillation frequency tuning counterweight 10, an electromagnetic coil connecting shaft 11, a linear bearing 12, and a leading edge oscillation limiting block 13.

[0021] The oscillating folding connector 1 is a folding structure with a flexible hinge at the connection point with the leading edge oscillating limit block 13. The oscillating folding connector 1 is connected to the insert 4 inside the blade near the leading edge of the blade by bolts. The oscillating folding connector 1 is connected to the leading edge oscillating limit block 13 and the electromagnetic coil connecting shaft 11 near the trailing edge of the blade by bolts. The electromagnetic coil 9 is connected through the electromagnetic coil connecting shaft 11, the oscillating frequency tuning counterweight 10, and a nut. The smooth section of the electromagnetic coil connecting shaft 11 is inside the linear bearing 12. The linear bearing 12 is bolted to the flapping folding connector 3 near the leading edge. The flapping folding connector 3 is bolted to the inserts on the root side and tip side of the blade. The flapping frequency tuning counterweight is bolted to the folding connector. The permanent magnet 7 is placed inside the middle groove of the flapping folding connector 3, and there is a permanent magnet cover plate 6 near the upper wing surface. The permanent magnet cover plate 6 and the flapping frequency tuning counterweight 8 are connected by bolts.

[0022] Furthermore, the electromagnetic coil 9 has a boss inside near the trailing edge of the blade, which is connected to the boss of the electromagnetic coil connecting shaft 11. The electromagnetic coil 9 is connected to the oscillating frequency modulation counterweight 10 and the nut via a nut near the leading edge of the blade.

[0023] Furthermore, the electromagnetic coil connecting shaft 11 is mainly divided into three parts: the side near the boss is threaded, which, together with the nut, enables the electromagnetic coil to be pressed and fixed; the part near the linear bearing 12 has a smooth surface, enabling the linear movement of the electromagnetic coil; and the end near the threaded hole is flat, which facilitates the connection between the swing folding connector 1 and the front edge swing limit block 13.

[0024] Furthermore, the oscillation frequency-modulating counterweight 10 has a groove near the axis for placing a nut, ensuring that the nut is embedded in the groove; at the same time, the frequency-modulating counterweight can not only adjust the frequency of the oscillation direction, but also effectively limit the electromagnetic coil along the oscillation direction.

[0025] Furthermore, the leading edge oscillation limiting block 13 can effectively prevent components such as the electromagnetic coil 9 from colliding with components such as the permanent magnet under external load, thereby affecting the function.

[0026] The permanent magnet 7 is a material with strong magnetism, and the magnetization direction is the thickness direction, i.e. the chord direction of the blade; The oscillation folding connecting piece 1 is close to the front edge variable pitch axis, effectively reduces the influence of other loads on the section of waving, oscillation and torsion, and the structure has a flexible hinge at the connecting position of the front edge oscillation limiting block 13, which can effectively reduce the clamping of the front edge connecting piece and the linear bearing under the action of centrifugal force, and the oscillation direction stiffness is low, so that the electromagnetic coil can cut the magnetic induction line movement; The blade vibration absorbing device increases the stiffness of the upper and lower skins of the blade, and can effectively limit the movement of the device, and when the vibration absorbing device fails or is damaged, the blade still exists inside to ensure that each component is separated, thereby ensuring safety; In addition, the device increases the limiting device (front edge oscillation limiting block), and the structure is safer to avoid accidents; when the device is abnormal, it is still inside the blade and does not separate; The outer ring of the blade inlay 4 is wound through a girder, and is solidified together with the blade during molding, thereby providing a connecting interface for each connecting piece. The circuit board 2 can increase pure resistance to realize passive vibration absorption, and can also increase power supply to form a semi-active control system for vibration reduction, in addition, negative resistance, negative inductance, etc. can be added in the circuit board by changing the circuit board, designing the circuit and increasing the power supply, so as to realize active vibration absorption.

[0027] The waving folding connecting piece 3 can produce elastic deformation when the blade waves, and will not affect the vibration frequency and effect.

[0028] The battery and the circuit board 2 are close to the front edge of the blade, so that the center of gravity of the blade is moved to before the variable pitch axis of the blade (close to the front edge of the blade), and in addition, the weight of the battery can provide certain frequency adjustment counterweight effect for the dynamics of the blade.

[0029] The application provides a helicopter blade vibration absorbing device based on a branch circuit, and the overall structure of the device is as shown in Figure 1As shown, the device includes an electromagnetic coil 9, a permanent magnet 7, and a battery and circuit board 2; when the blade is subjected to a flapwise load, the electromagnetic coil connected to the leading edge of the blade moves under the excitation of the external load. Since the permanent magnet in the blade moves in a direction inconsistent with the electromagnetic coil, the distance between the electromagnetic coil and the permanent magnet changes. Since the magnetic field experienced by the electromagnetic coil changes, the electromagnetic coil moves in a direction cutting the magnetic induction lines, thus generating an induced electromotive force in the corresponding branch circuit. There is a resistor in the circuit. When in the active passive vibration absorption mode, the electromagnetic coil of the device converts the kinetic energy of the magnetic sensor into heat energy. The electromagnetic force generated by the electromagnetic coil is transmitted to the leading edge of the blade through the flapwise connecting member, thereby reducing the flapwise load of the blade and increasing the equivalent damping in the flapwise direction of the blade. When in the semi-active vibration absorption mode, the semi-active vibration absorption mode has better vibration absorption effect and wider vibration absorption frequency range than the passive mode. The device uses a battery and a corresponding circuit board to make the vibration absorption frequency wider.

[0030] The piezoelectric sheet 5, the battery and the circuit board 3, when the blade is subjected to an external load, the connecting member in the vibration absorption device will deform, thus the piezoelectric sheet pasted on its surface will also deform. Due to the positive piezoelectric effect of the piezoelectric sheet, an electric current is generated. In combination with the branch circuit, the electric current generated by the piezoelectric sheet generates heat through the resistor, thus converting the kinetic energy of the folded connecting member into heat energy. When the folded connecting member deforms, the reaction force generated is transmitted to the folded connecting member, and then to the blade body, thereby absorbing the vibration of the blade.

[0031] The flapwise frequency adjustment weight 8 can be used to adjust the vibration absorption frequency to be close to the resonant frequency of the circuit when there is a deviation between the two, thereby maximizing the vibration absorption effect. The flapwise frequency adjustment weight 8 can be used to adjust the vibration absorption frequency to be close to the resonant frequency of the circuit when there is a deviation between the two, thereby maximizing the vibration absorption effect. The leading edge flapwise limiting block 13 can effectively limit the movement of the electromagnetic coil and prevent the electromagnetic coil from colliding with the permanent magnet, ensuring the safety and reliability of each component.

[0032] The flapwise folded connecting member 3 is provided with a groove stop in the middle structure, which can effectively install and fix the permanent magnet 7 and the linear bearing 12. In addition, the blade is in a centrifugal field during actual use, so each component is subjected to a large centrifugal force. This structure can effectively transmit the centrifugal load of each component.

[0033] The linear bearing 12 can effectively limit the movement direction of the electromagnetic coil and effectively ensure the cutting magnetic induction line movement of the electromagnetic coil, so that the magnetic field changes at the fastest speed and the movement direction is easy to control. The pendulum folding connecting piece 1 is provided with a flexible hinge, and the electromagnetic coil can avoid being stuck in the movement of the blade.

[0034] The working principle of the present application is that: The device mainly utilizes an electromagnetic coil, a permanent magnet and a branch circuit to convert kinetic energy into heat energy.

[0035] The electromagnetic branch circuit utilizes the basic principle of electromagnetism. Firstly, the wire of the closed circuit cuts the magnetic induction lines in the magnetic field, and an induced current is generated in the wire. Then, the vibration energy is dissipated in the circuit through the damping in the branch circuit, and finally the conversion of kinetic energy into heat energy is realized, thereby realizing the vibration control of the structure. When the vibration absorbing device absorbs the vibration in the pendulum direction, the pendulum folding connecting piece is placed along the chord direction, and the stiffness in the pendulum direction is small. Therefore, under the action of external load excitation, the electromagnetic coil will reciprocate along the chord direction of the blade. At this time, the strength of the magnetic field acting on the coil is constantly changing, and the induced current is generated by the coil cutting the magnetic induction lines. Therefore, the vibration energy absorbed is converted into electric energy as much as possible, and is dissipated in the circuit in the form of heat energy, thereby achieving the vibration absorption effect. When the passive mode is adopted, the resistance and the capacitance constitute a second-order resonance circuit, so that the resonance frequency is close to the vibration absorption frequency, thereby making the energy dissipation in the circuit maximum. This mode is similar to the anti-resonance electronic vibration absorber. When the semi-active mode is adopted, the corresponding negative resistance and capacitance type and negative impedance type electromagnetic branch circuit can be constructed, so that the vibration absorption frequency is widened, and the problem of passive damping affected by frequency is solved.

[0036] The piezoelectric branch circuit utilizes the electromechanical coupling performance of the piezoelectric sheet. When the folding beam deforms, the strain sheet pasted on its surface generates electric charge. The resistance, capacitance and the like are changed in the branch circuit to realize the resonant branch circuit, thereby achieving the vibration reduction purpose. The device utilizes the advantages of light structure, rapid actuation and the like of the piezoelectric material. When the vibration absorbing device absorbs the vibration in the flapwise direction, when the vibration is absorbed by the permanent magnet, the mass / constraint of the folding beam where the electromagnetic coil is located and the folding beam where the permanent magnet is located is inconsistent. Therefore, the electromagnetic coil and the permanent magnet reciprocate along the thickness direction of the blade airfoil, and then cut the magnetic induction lines to generate an induced current, and finally realize the conversion of kinetic energy into heat energy. When the vibration absorbing device absorbs the vibration in the spanwise direction of the blade, the constraint boundary of the folding beam connecting piece close to the leading edge and the folding beam connecting piece close to the trailing edge is inconsistent. Therefore, the electromagnetic coil and the permanent magnet do not move along the spanwise direction of the blade by the same amount, and then cut the magnetic induction lines to generate an induced current. Then, the electric energy is converted into heat energy through the circuit board, thereby realizing the vibration absorption.

[0037] The folding beam structure in the vibration absorbing device is a continuous structure, can be stably supported and has effective stiffness in the sensitive direction, so that the structural form can be introduced into the vibration absorbing device. The folding beam structure is combined with the piezoelectric sheet in the device, and the corresponding branch circuit is combined to enhance the vibration absorbing efficiency.

Claims

1. A vibration absorbing device for a helicopter blade embedded in the blade based on a branch circuit, characterized by, The utility model relates to a kind of vibration absorber, including: Pitching folding connecting piece (1), flapping folding connecting piece (3), paddle inlay (4), piezoelectric sheet (5), permanent magnet (7), electromagnetic coil (9), electromagnetic coil connecting shaft (11), linear bearing (12); Two flapping folding connecting pieces (3) are arranged in parallel along the blade spanwise, and both ends are connected inside the blade through paddle inlay (4); Permanent magnet (7) is fixedly connected in the middle groove of the flapping folding connecting piece (3) close to the trailing edge of the blade;Linear bearing (12) is fixedly connected in the middle groove of the flapping folding connecting piece (3) close to the leading edge of the blade;Electromagnetic coil connecting shaft (11) is slidably arranged in linear bearing (12). Electromagnetic coil (9) is sleeved on the first end of electromagnetic coil connecting shaft (11) and located between the two flapping folding connecting pieces (3);Electromagnetic coil (9) is connected to the first circuit board. The second end of electromagnetic coil connecting shaft (11) is connected to the first end of pitching folding connecting piece (1), and the second end of pitching folding connecting piece (1) is connected inside the leading edge of the blade through paddle inlay (4). At least one piezoelectric sheet (5) is arranged on pitching folding connecting piece (1) and / or flapping folding connecting piece (3), and each piezoelectric sheet (5) is connected to the second circuit board. Each circuit board includes a capacitor and a resistor, and the resonant frequency of the circuit board is determined according to the vibration absorption frequency;Or, each circuit board includes a power supply, a capacitor and a resistor, forming a negative resistance and capacitance type and a negative impedance type electromagnetic branch circuit to realize vibration absorption.

2. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 1, characterized in that, Flapping frequency modulation counterweight (8) is arranged on flapping folding connecting piece (3) for adjusting the vibration absorption frequency.

3. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 1, characterized in that, Pitching frequency modulation counterweight (10) is sleeved on electromagnetic coil connecting shaft (11) and located on the side of the pitching folding connecting piece (1) facing electromagnetic coil (9). Pitching frequency modulation counterweight (10) is used to adjust the vibration absorption frequency.

4. The shunt circuit based helicopter blade embedded vibration absorber of claim 1, wherein, Front edge pitching limiting block (13) is arranged at the second end of electromagnetic coil connecting shaft (11) to limit the movement distance of electromagnetic coil (9) towards permanent magnet (7).

5. The shunt circuit based helicopter blade embedded vibration absorber of claim 1, wherein, The electromagnetic coil (9) is threadedly connected with the electromagnetic coil connecting shaft (11).

6. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 1, characterized in that, Permanent magnet cover plate (6) is arranged at the position close to the upper surface of the blade of permanent magnet (7).

7. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 1, characterized by, Boss is arranged inside the side close to the trailing edge of the blade of electromagnetic coil (9) to face the boss of electromagnetic coil connecting shaft (11), and pitching frequency modulation counterweight (10) and nut are connected through nut close to the leading edge of the blade of electromagnetic coil (9).

8. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 7, characterized in that, Pitching frequency modulation counterweight (10) is provided with a groove close to the position of the shaft center for placing the nut to ensure that the nut is embedded in the groove.

9. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 1, characterized by, The permanent magnet (7) is made of a material with strong magnetism, and the magnetization direction is the thickness direction, i.e. the chord direction of the blade.

10. The shunt circuit based helicopter blade embedded vibration absorption device according to claim 1, characterized by, The circuit board is close to the leading edge of the blade, so that the center of gravity of the blade moves to the front of the variable-pitch axis of the blade.

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