Piezoelectric type negative stiffness collaborative vibration absorption supporting rod for helicopter rotor dynamic load

Abstract

The invention relates to a piezoelectric type negative stiffness collaborative vibration absorption supporting rod for a helicopter rotor dynamic load. The piezoelectric type negative stiffness collaborative vibration absorption supporting rod comprises an upper supporting rod body, a lower supporting rod body and a vibration absorption assembly which is arranged between the upper supporting rod body and the lower supporting rod body and used for vibration isolation. The vibration absorption assembly comprises an auxiliary circular ring used for bearing a static load, a lever spring and a disc spring used for providing negative stiffness and adjustable pre-compression are arranged in the auxiliary circular ring, and a mass block used for absorbing and dissipating vibration energy is arranged below the disc spring; the two sides of the lever spring make contact with the piezoelectric ceramic stack, the piezoelectric ceramic stack is connected with the multi-mode external circuit module, the multi-mode piezoelectric shunt damping effect is formed, and meanwhile a plurality of mode components of the system are controlled. When vibration is large, electric energy is stored, and when vibration is small, the mode is switched to a multi-mode RLC circuit dissipation mode, and mechanical vibration energy is converted into electric energy which is consumed through the circuit. Negative stiffness dynamic low-frequency broadband vibration absorption and piezoelectric shunt multi-mode suppression are coupled, and the effect of efficient vibration isolation is achieved.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology, and in particular to a piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic loads. Background Technology

[0002] Helicopters possess strong load-bearing capacity and adaptability to complex environments, offering significant advantages in heavy transport, long-range emergency rescue, and urban air mobility. However, the aerodynamic loads on the rotor during flight generate severe vibrations, which are transmitted to the fuselage via the rotor hub-main gearbox-strut path, resulting in the fuselage being subjected to a harsh vibration environment for extended periods. Excessive vibration not only accelerates structural fatigue damage and causes failure of critical components but also significantly reduces helicopter safety and passenger comfort. The variable flight conditions of helicopters cause the rotor to be subjected to asymmetric and unsteady aerodynamic excitations, resulting in elastic and rigid body motions in the blades. These motions combine at the rotor hub to generate alternating forces and torques, which are transmitted to the fuselage, producing low-frequency, high-amplitude multi-harmonic vibrations (12-30Hz) dominated by the blade frequency (kNΩ, where N is the number of blades and Ω is the rotor speed).

[0003] To address the aforementioned low-frequency vibration problem, various vibration isolators are typically installed between the main shock absorber and the fuselage to reduce the force transmission rate to the fuselage. Traditional dynamic vibration absorbers have drawbacks such as large added mass, narrow bandwidth, and a single isolation frequency. Active vibration isolation requires corresponding controllers, power amplifiers, and consideration of the control algorithm's stability, increasing system complexity.

[0004] Patent ZL202210435412.2 introduces a negative stiffness element into a dynamic vibration absorber, significantly improving the suppression effect of low-frequency wide-amplitude vibration while ensuring static stability; however, it only controls a single modal frequency. The vibration caused by the dynamic load on a helicopter rotor is a low-frequency, high-amplitude, multi-harmonic vibration, so controlling only one modal frequency has limited vibration reduction effect. Therefore, this invention proposes a novel piezoelectric negative stiffness vibration-absorbing strut based on existing struts. This strut has an auxiliary ring added to its lower part to bear the static load of the fuselage; subsequently, the auxiliary ring is connected to a negative stiffness dynamic vibration absorber—a piezoelectric ceramic stack piezoelectric shunt resistor damper. When the piezoelectric negative stiffness vibration-absorbing strut is working, on the one hand, when the natural frequency of the negative stiffness vibration absorber is near the main modal frequency, the absorbing block generates a large resonant inertial reaction force, achieving vibration isolation. On the other hand, during the transmission of vibration, some energy is dissipated through the piezoelectric ceramic stack—multi-branch piezoelectric shunt circuit—forming resistive damping, achieving multi-modal vibration absorption. By coordinating the inertial reaction force and the piezoelectric shunt damping, multiple resonance peaks can be controlled simultaneously, thereby achieving multimodal vibration suppression. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by proposing a piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic loads.

[0006] The technical solution of this invention: A piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic load includes an upper strut and a lower strut, and a vibration-absorbing component for vibration isolation disposed between the upper strut and the lower strut; The vibration absorption assembly includes an auxiliary ring for bearing static loads, within which are a lever spring and a disc spring for providing negative stiffness and adjustable pre-compression. Below the disc spring is a mass block for absorbing and dissipating vibration energy. The lever spring is in contact with the piezoelectric ceramic stack on both sides. The piezoelectric ceramic stack is connected to the multi-mode external circuit module to form a multi-mode piezoelectric shunt damping effect, while controlling multiple modal components of the system. When vibration is high, electrical energy is stored; when vibration is low, the circuit switches to a multi-mode RLC circuit dissipation mode to convert mechanical vibration energy into electrical energy and dissipate it through the circuit. An RLC network (R represents resistance, L represents inductance, and C represents parallel negative capacitance) is added to the shunt circuit of the piezoelectric ceramic stack. The parameters of RL are dynamically adjusted through vibration frequency feedback signals to maximize the mechanical energy to electrical energy conversion efficiency.

[0007] Optionally, a rubber block is provided inside the mass block, and a connecting rod is provided at the center of the rubber block. The top end of the connecting rod passes through the mass block, the disc spring, and the auxiliary ring in sequence.

[0008] Optionally, the top end of the connecting rod is threaded, and one end of the upper support rod is movably connected to the threaded end of the connecting rod, so that the negative stiffness value can be adjusted in real time by rotating the connecting rod.

[0009] Optionally, the multimodal external circuit module is an external energy dissipation circuit. The external energy dissipation circuit is designed with a bidirectional energy management mode, including a supercapacitor circuit and a variable multimodal RLC circuit. When the vibration energy is large, the energy dissipation circuit cannot dissipate the vibration energy in time and store it in the supercapacitor; when the vibration energy is small, it switches to the dissipation mode.

[0010] Optionally, vibration-absorbing struts are installed on the machine body. A main damper is provided on the top of the machine body, and two upper struts for transmitting vibration are provided on both sides of the main damper. Two sets of lower struts for transmitting vibration are provided on the top of the machine body.

[0011] Optionally, the auxiliary ring is provided with a protective structure on its exterior to protect the vibration-absorbing assembly.

[0012] Compared with the prior art, the present invention has the following beneficial technical effects: 1. The present invention uses an adjustable pre-compression disc spring module, rubber, mass block, lever spring, piezoelectric ceramic stack, and external circuit module. The disc spring can provide negative stiffness and together with the rubber and mass block, it forms a negative stiffness dynamic vibration absorber, which can achieve low-frequency vibration isolation. 2. This invention uses a piezoelectric ceramic stack and an external circuit module to form a piezoelectric shunt damper. When the vibration is large, electrical energy is stored in a supercapacitor; when the energy is small, it switches to a variable RLC circuit dissipation mode to convert mechanical vibration energy into electrical energy and consume it through the circuit. By dynamically adjusting the parameters of the RLC circuit, the mechanical energy to electrical energy conversion efficiency is maximized. This invention couples negative stiffness dynamic low-frequency broadband vibration absorption with piezoelectric shunt multimode suppression damping to achieve a highly efficient vibration isolation effect.

[0013] 3. The disc spring of this invention can achieve real-time stiffness adjustment through the connecting rod, which improves the frequency adaptability of traditional devices, enhances energy efficiency through bidirectional energy distribution, and makes the equipment easier to control and maintain in the later stages. Attached Figure Description

[0014] Figure 1 A three-dimensional structural schematic diagram of the present invention is provided; Figure 2 A three-dimensional schematic diagram of the present invention after removing the protective structure is provided; Figure 3 A cross-sectional schematic diagram of the vibration-absorbing component in this invention is provided; Figure 4 An exploded view of the protective structure in this invention is provided; Figure 5 A schematic diagram showing the separation of the connecting rod, rubber block, and mass block in this invention is provided; Figure 6 An enlarged structural schematic diagram of point A in this invention is provided; Figure 7 An enlarged structural schematic diagram of point B in this invention is provided; Figure 8 An enlarged structural schematic diagram of point C in this invention is provided; Figure 9 The flowchart of the operation of this invention is provided; Figure 10 The piezoelectric ceramic stack combined with the multi-mode energy dissipation circuit diagram of the present invention is given; Figure 11 A diagram illustrating the vibration reduction effect of this invention is provided.

[0015] Figure label: 1. Organism; 2. Main reduction; 3. Connecting frame; 4. Upper support rod; 5. Lower support rod; 6. Vibration-absorbing assembly; 601. Auxiliary ring; 602. Lever spring; 603. Piezoelectric ceramic stack; 604. Connecting rod; 605. Rubber block; 606. Mass block; 607. Disc spring; 7. Protective structure; 701. Housing 1; 702. Housing 2; 703. Slot; 704. Positioning hole; 705. Insert plate; 706. Storage hole; 707. Cylindrical spring; 708. Guide plate; 709. Positioning rod; 710. Heat dissipation hole. Detailed Implementation

[0016] The technical solutions of this disclosure will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments.

[0017] The components of the embodiments of this disclosure, which are typically described and shown in the accompanying drawings, can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of embodiments of this disclosure provided in the drawings is not intended to limit the scope of the claimed disclosure, but merely to illustrate selected embodiments of the disclosure.

[0018] Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this disclosure.

[0019] In the description of this disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0020] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0021] Example:

[0022] like Figures 1-11As shown, the present invention proposes a piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic loads, including an upper strut 4 and a lower strut 5, and a vibration-absorbing assembly 6 for vibration isolation disposed between the upper strut 4 and the lower strut 5. The system includes a fuselage 1, a main damper 2 located on the top of the fuselage 1, two upper struts 4 for transmitting vibration on both sides of the main damper 2, and two sets of lower struts 5 for transmitting vibration on the top of the fuselage 1. The vibration damping assembly 6 includes an auxiliary ring 601 for bearing the static load of the body 1. The main reducer 2 is provided with two connecting brackets 3. The two connecting brackets 3 are respectively movably connected to two upper support rods 4 on their opposite sides. The upper end of the lower support rod 5 passes through the bottom of the auxiliary ring 601 and is movably connected to the inner wall of the bottom of the auxiliary ring 601. The auxiliary ring 601 is provided with a lever spring 602 and an adjustable pre-compression disc spring 607 for achieving the negative stiffness effect.

[0023] The electric negative stiffness collaborative vibration absorption strut also includes a piezoelectric shunt control system. The piezoelectric shunt control system includes a piezoelectric ceramic stack 603 and a variable RLC circuit set on the inner walls of both sides of the auxiliary ring 601. An RLC network is added to the shunt circuit of the piezoelectric ceramic stack 603. The parameters of RL are dynamically adjusted through the vibration frequency feedback signal to maximize the mechanical energy to electrical energy conversion efficiency. The piezoelectric ceramic stack 603 converts mechanical energy into electrical energy and consumes it, thereby effectively reducing vibration and noise in the mechanical system and improving the stability and reliability of the equipment. Below the disc spring 607, there is a mass block 606 for absorbing and dissipating vibration energy. The piezoelectric ceramic stack 603 and the mass block 606 are connected in series or in parallel, and multiple sets are set to form a graded vibration absorption structure. The lever spring 602 is in contact with the piezoelectric ceramic stack 603 on both sides. The piezoelectric ceramic stack 603 is connected to the multi-mode external circuit module to form a multi-mode piezoelectric shunt damping effect, and at the same time control multiple modal components of the system. When the vibration is large, electrical energy is stored; when the vibration is small, the circuit switches to a multi-mode RLC circuit dissipation mode to convert mechanical vibration energy into electrical energy and consume it through the circuit.

[0024] Taking the multimodal external circuit module as an example with three branches, it simultaneously controls the peak values ​​of three modes; each branch includes two parts: filtering and power consumption; that is, each branch only controls one mode component.

[0025] The vibration reduction effect diagram shows a comparison of the frequency response curves of the airframe vibration transmissibility before and after using the device of this invention. Within the 12-30Hz range (the typical blade frequency vibration band of a helicopter), the vibration amplitude is significantly reduced, and the low-frequency suppression effect is good.

[0026] Multimodal peak control: Multiple resonance peaks are simultaneously suppressed, verifying the synergistic effect of negative stiffness vibration absorption and piezoelectric shunt damping. Furthermore, the vibration absorption bandwidth is broadened, covering the main harmonic components of the rotor dynamic load, solving the problem of narrow bandwidth in traditional vibration absorbers. Therefore, this invention achieves efficient low-frequency vibration isolation and multimodal energy dissipation, improving helicopter flight stability and comfort.

[0027] Specifically, the mass block 606, in conjunction with the disc spring 607, lever spring 602, and rubber block 605, generates a motion opposite to the main vibration when the system is subjected to vibration excitation, thereby consuming vibration energy and achieving the purpose of vibration absorption. The mass block 606 contains a rubber block 605, which serves as a positive stiffness. When subjected to external force, it generates a restoring force opposite to the direction of the external force, thus achieving the effect of vibration absorption and isolation. A connecting rod 604 is provided at the center of the rubber block 605. The top of the connecting rod 604 passes through the mass block 606, disc spring 607, and auxiliary ring 601 in sequence. In order to adjust the negative stiffness of the disc spring 607, the top of the connecting rod 604 is threaded. The bottom end of the upper support rod 4 is movably connected to the connecting rod 604. Rotating the connecting rod 604 can adjust the negative stiffness value of the disc spring 607 in real time.

[0028] Besides the aforementioned method of adjusting the negative stiffness of the disc spring 607, another method can be used, such as setting an electromagnetic adjustment component. This component consists of an electromagnetic coil coiled at the outer bottom of the disc spring 607, forming an electromagnet structure in the upper gap. Based on the magnitude of vibration, the electromagnetic force is automatically adjusted, thereby changing the negative stiffness of the disc spring 607. By dynamically changing the magnetic field strength, the pre-compression of the disc spring 607 can be adjusted, thus regulating the negative stiffness value in real time. To further protect the device, the auxiliary ring 601 is equipped with a protective structure 7 for protecting the vibration-absorbing assembly 6. The protective structure 7 includes a first housing 701 and a second housing 702. The first housing 701 and the second housing 702 provide protection, thereby extending the service life of the vibration-absorbing assembly 6. Multiple insert plates 705 and slots 703 are respectively provided on the adjacent sides of the first housing 701 and the second housing 702. Positioning holes 704 are provided on the inner wall of the slots 703. A receiving hole 706 is provided at the top of the insert plate 705. A positioning rod 709 is movably installed in the receiving hole 706. A guide plate 708 is fixedly installed at the bottom of the positioning rod 709. The guide plate 708 and the receiving hole 706 are movably connected. The inner wall of the receiving hole 706 is provided with two limiting grooves. A cylindrical spring 707 is fixedly provided at the bottom of the guide plate 708. The bottom of the cylindrical spring 707 is fixedly connected to the bottom inner wall of the receiving hole 706. Two limiting blocks are fixedly provided on the outside of the guide plate 708. The limiting blocks are movably connected to the limiting grooves. The positioning rod 709 is adapted to the positioning hole 704. The cooperation of the positioning rod 709, the positioning hole 704, the slot 703 and the cylindrical spring 707 can quickly disassemble the housing 1 701 and the housing 2 702, which is convenient for subsequent maintenance of the internal components of the vibration absorption assembly 6. Multiple heat dissipation holes 710 are provided on the inner walls of the housing 1 701 and the housing 2 702. The heat dissipation holes 710 can ensure the heat dissipation performance of the vibration absorption assembly 6.

[0029] In this embodiment, the upper support rod 4 is used to transmit vibration. The upper support rod 4 transmits the vibration to the connecting rod 604, and the connecting rod 604 then transmits the vibration to the disc spring 607, lever spring 602, rubber block 605, and mass block 606. The disc spring 607 and lever spring 602 can provide negative stiffness. The mass block 606, in conjunction with the above accessories, generates a motion opposite to the main vibration when the system is subjected to vibration excitation, thereby consuming vibration energy and achieving the purpose of vibration absorption. The rubber block 605 can provide positive stiffness. When subjected to external force, it generates a restoring force opposite to the direction of the external force, thereby achieving the effect of vibration absorption and isolation. When the upper support rod 4 transmits vibration, the piezoelectric ceramic stack 603 converts mechanical energy into electrical energy and consumes it, thereby effectively reducing vibration and noise in the mechanical system and improving the stability and reliability of the equipment. Through the coupling of negative stiffness dynamic low-frequency broadband vibration absorption and piezoelectric shunt multimodal suppression resistance damping, the effect of efficient vibration isolation is achieved.

[0030] During the experiment, Figure 1 All components in the system are made of stainless steel with a density of 7850 and a Poisson's ratio of 0.3; the main reducer weighs 950 kg, and the machine body weighs 2280 kg; the strut stiffness is 3.2e7 N / m, the auxiliary ring stiffness is 9.2e6 N / m, the rubber stiffness is 7.5e6 N / m, the rubber damping is 150 N·s / m, and the disc spring negative stiffness is -2e6 N / m. 2The vibration-absorbing mass is 15kg; in addition, the lever spring has a strength of 6e6N / m, and the piezoelectric ceramic stack has a d... 33 The piezoelectric strain constant is 593e-12 m / V, and the elastic compliance is 20.7e-12 m. 2 / N), piezoelectric sheet thickness 0.1mm, number of piezoelectric sheets 500, piezoelectric sheet area 2.5e-5 m² 2 .

[0031] A vertical frequency sweep excitation was applied above the main reducer, and a response was obtained at the body. Figure 11 The frequency response function curves of the piezoelectric negative stiffness synergistic vibration-absorbing struts are shown. The results indicate that installing the synergistic vibration-absorbing struts can simultaneously control the first few main modes that have a greater impact on the vertical vibration of the system, thereby achieving vibration isolation.

[0032] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A piezoelectric negative stiffness synergistic vibration-absorbing strut for helicopter rotor dynamic loads, characterized in that: Includes an upper support rod (4) and a lower support rod (5), and a vibration-absorbing assembly (6) for vibration isolation disposed between the upper support rod (4) and the lower support rod (5); The vibration absorption assembly (6) includes an auxiliary ring (601) for bearing static loads. The auxiliary ring (601) contains a lever spring (602) and a disc spring (607) for providing negative stiffness and adjustable pre-compression. Below the disc spring (607) is a mass block (606) for absorbing and dissipating vibration energy. The lever spring (602) is in contact with the piezoelectric ceramic stack (603) on both sides. The piezoelectric ceramic stack (603) is connected to the multi-mode external circuit module to form a multi-mode piezoelectric shunt damping effect, and at the same time control multiple modal components of the system. When the vibration is large, electrical energy is stored; when the vibration is small, the circuit switches to a multi-mode RLC circuit dissipation mode to convert mechanical vibration energy into electrical energy and consume it through the circuit.

2. The piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic load as described in claim 1, characterized in that, The mass block (606) contains a rubber block (605), and a connecting rod (604) is provided at the center of the rubber block (605). The top end of the connecting rod (604) passes through the mass block (606), the disc spring (607), and the auxiliary ring (601) in sequence.

3. A piezoelectric negative stiffness synergistic vibration-absorbing strut for helicopter rotor dynamic loads according to claim 2, characterized in that, The top of the connecting rod (604) is threaded, and one end of the upper support rod (4) is movably connected to the threaded end of the connecting rod (604). The negative stiffness value can be adjusted in real time by rotating the connecting rod (604).

4. A piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic loads according to claim 1, characterized in that, The multimodal external circuit module is an external energy dissipation circuit. The external energy dissipation circuit is designed with a bidirectional energy management mode, including a supercapacitor circuit and a variable multimodal RLC circuit. When the vibration energy is large, the energy dissipation circuit cannot dissipate the vibration energy in time and store it in the supercapacitor; when the vibration energy is small, it switches to the dissipation mode.

5. A piezoelectric negative stiffness synergistic vibration-absorbing strut for helicopter rotor dynamic loads according to claim 1, characterized in that, The vibration-absorbing strut is installed on the machine body (1). The main damper (2) is provided on the top of the machine body (1). Two upper struts (4) for transmitting vibration are provided on both sides of the main damper (2). Two sets of lower struts (5) for transmitting vibration are provided on the top of the machine body (1).

6. A piezoelectric negative stiffness synergistic vibration-absorbing strut for helicopter rotor dynamic loads according to claim 1, characterized in that, The auxiliary ring (601) is provided with a protective structure (7) for protecting the vibration absorption assembly (6).

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