Method and system for regulating and controlling vibration characteristics of acoustic black hole structure

Abstract

The invention belongs to the technical field of vibration control, and discloses a method and system for regulating and controlling the vibration characteristic of an acoustic black hole structure. An acoustic black hole structure is additionally installed on a controlled structure, and the thickness of the acoustic black hole structure changes according to a power exponent rule; adding a piezoelectric element on the acoustic black hole structure to obtain a piezoelectric-acoustic black hole composite structure; the piezoelectric element is connected with an external branch circuit, and the external branch circuit is used for conducting vibration characteristic regulation and control on the piezoelectric-acoustic black hole composite structure. According to the invention, the low-frequency vibration suppression performance of the acoustic black hole structure can be optimized, and efficient vibration control in a broadband range is realized.

Description

Technical Field

[0001] The present invention belongs to the field of vibration control technology, and more specifically, relates to a method and system for regulating the vibration characteristics of an acoustic black hole structure. Background Art

[0002] With the rapid development of industrial equipment and aerospace technology, vibration control technology has become a key area to improve structural performance and reliability. The Acoustic Black Hole (ABH) structure performs well in medium and high frequency vibration control due to its energy gathering characteristics, but it is insufficient in low frequency vibration suppression, which limits its application potential in broadband vibration control.

[0003] At present, the acoustic black hole structure is in the development stage, and its application in complex vibration environments still faces challenges. Therefore, an innovative technical solution is urgently needed to further improve the low-frequency and broadband vibration control capabilities of the acoustic black hole structure and expand its actual application scenarios in high-performance structures. Summary of the invention

[0004] The present invention solves the problem in the prior art that the low-frequency and broadband vibration control capabilities of acoustic black hole structures need to be further improved by providing a method and system for regulating the vibration characteristics of an acoustic black hole structure.

[0005] The present invention provides a method for regulating the vibration characteristics of an acoustic black hole structure. The acoustic black hole structure is additionally installed on a controlled structure, and the thickness of the acoustic black hole structure changes according to a power law. A piezoelectric element is attached to the acoustic black hole structure to obtain a piezoelectric-acoustic black hole composite structure. The piezoelectric element is connected to an external branch circuit, and the vibration characteristics of the piezoelectric-acoustic black hole composite structure are regulated by using the external branch circuit.

[0006] Preferably, the external branch circuit includes capacitors, resistors and inductors connected in series / parallel; and the vibration characteristics of the acoustic black hole structure are adjusted by introducing nonlinear characteristics using the external branch circuit.

[0007] Preferably, the vibration characteristics of the acoustic black hole structure are dynamically adjusted by adjusting at least one parameter among the capacitance value, inductance value and resistance value in the external branch circuit, so as to achieve effective coupling of the vibration modal characteristics of the acoustic black hole structure and the controlled structure.

[0008] Preferably, the expression of the acoustic black hole structure displacement response w(x, t) is set as: in, is the shape function of the acoustic black hole structure displacement; a(t) is the weight coefficient of the corresponding shape function, which is also the discretized generalized coordinate;

[0009] According to the principle of minimum potential energy, the Lagrangian equation of the electromechanical coupling system including the piezoelectric-acoustic black hole composite structure and the external branch circuit is constructed as follows:

[0010]

[0011] Where M is the mass matrix of the piezoelectric-acoustic black hole composite structure, L is the inductance in the external branch circuit, R is the resistance in the external branch circuit, C is the capacitance in the external branch circuit, K is the stiffness matrix of the piezoelectric-acoustic black hole composite structure, image(K) is the imaginary part of the stiffness matrix, real(K) is the real part of the stiffness matrix, ω is the external excitation frequency, and f ext (t) is the external stimulus, is the first-order derivative of the discretized generalized coordinates, is the second-order derivative of the discretized generalized coordinates; q(t) is the charge; is the first-order derivative of the charge, and V p The function of R, that is V p is the voltage value across the piezoelectric element; is the second-order derivative of the charge; Θ is the electromechanical coupling coefficient, Θ T is the transpose of the electromechanical coupling coefficient; C p is the capacitance of the piezoelectric element, C p -1 It is the reciprocal of the capacitance of the piezoelectric element.

[0012] Preferably, a modal analysis and vibration characteristic regulation test are performed on the electromechanical coupling system including the piezoelectric-acoustic black hole composite structure and the external branch circuit;

[0013] According to the modal analysis results and vibration characteristic regulation test results of the electromechanical coupling system, the control parameters are optimized; the control parameters include the capacitance value, inductance value and resistance value in the external branch circuit.

[0014] Preferably, strain information of the acoustic black hole structure is acquired, and a setting position of the piezoelectric element on the acoustic black hole structure is determined according to the strain information.

[0015] Preferably, a modal analysis is performed on the acoustic black hole structure to obtain modal analysis results including the natural frequency, vibration mode and response characteristics of the acoustic black hole structure in multiple modes, and strain information including the strain distribution of the acoustic black hole structure in multiple modes is calculated based on the modal analysis results of the acoustic black hole structure.

[0016] Preferably, the method for regulating the vibration characteristics of the acoustic black hole structure further includes: providing a damping element on the acoustic black hole structure.

[0017] Preferably, the acoustic black hole structure is an additional acoustic black hole structure, and the additional acoustic black hole structure is designed as a one-dimensional beam structure, a two-dimensional spiral structure, a two-dimensional rectangular structure or a two-dimensional circular structure.

[0018] On the other hand, the present invention provides a system for regulating the vibration characteristics of an acoustic black hole structure, comprising: an acoustic black hole structure and a piezoelectric control unit; the acoustic black hole structure is additionally installed on a controlled structure, and the thickness of the acoustic black hole structure changes according to a power law; the piezoelectric control unit comprises a piezoelectric element attached to the acoustic black hole structure, and an external branch circuit connected to the piezoelectric element;

[0019] The system for regulating the vibration characteristics of an acoustic black hole structure is used to execute the above-mentioned method for regulating the vibration characteristics of an acoustic black hole structure.

[0020] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0021] The acoustic black hole structure in the present invention is additionally installed on the controlled structure, the thickness of the acoustic black hole structure changes according to the power law, a piezoelectric element is added to the acoustic black hole structure to obtain a piezoelectric-acoustic black hole composite structure, the piezoelectric element is connected to an external branch circuit, and the vibration characteristics of the piezoelectric-acoustic black hole composite structure are regulated by the external branch circuit. The present invention uses a dynamically adjustable external branch circuit to introduce nonlinear characteristics, which can achieve dynamic regulation of the piezoelectric branch circuit characteristics, can regulate the dynamic response of the piezoelectric element, and achieve the purpose of regulating the modal characteristics of the acoustic black hole structure, and then can regulate the vibration characteristics of the piezoelectric-acoustic black hole composite structure, significantly improving the controllability of the low-order modes of the acoustic black hole structure, and enhancing the regulation ability of the low-frequency vibration coupling characteristics, so that the acoustic black hole structure shows strong adaptability and flexibility in the regulation of low-frequency vibrations.

[0022] The present invention utilizes the nonlinear characteristics of the external branch circuit, not only optimizing the low-frequency dynamic vibration absorption control in the acoustic black hole structure, but also realizing comprehensive control from low frequency to high frequency by combining the nonlinear circuit parameter adjustment, and the adjustment method is flexible and can adapt to various working conditions and environmental requirements. The present invention combines the medium and high frequency energy gathering of the acoustic black hole and the low-frequency regulation of dynamic vibration absorption to meet the needs of broadband vibration control, and can achieve wide-band vibration suppression through multi-modal regulation. It has a wide regulation range and strong adaptability, can meet the needs of complex vibration working conditions, and does not need to introduce complex additional structures such as arrays in the regulation system.

[0023] In summary, the present invention enhances the dynamic vibration absorption effect of the acoustic black hole in the low frequency band and optimizes the low-frequency vibration suppression performance of the acoustic black hole structure by introducing the synergistic effect of the piezoelectric nonlinear characteristics and the acoustic black hole structure. At the same time, the acoustic black hole structure has the ability to efficiently absorb and dissipate wave energy in the high frequency range, thus achieving efficient vibration suppression of the controlled structure in a wide frequency range.

[0024] In addition, the present invention also determines the location of the piezoelectric element on the acoustic black hole structure according to the strain information, which can maximize the piezoelectric effect and thus obtain a better vibration control effect. The present invention can also set a damping element on the acoustic black hole structure, and the combination of the damping element can efficiently dissipate the mechanical vibration energy of the acoustic black hole structure, further optimizing the vibration control effect. The present invention also improves the integration of the vibration control system, reduces the system complexity, and improves the vibration control efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a system for regulating the vibration characteristics of an acoustic black hole structure provided by an embodiment of the present invention;

[0026] Figure 2 A circuit diagram of an external branch circuit in a system for regulating the vibration characteristics of an acoustic black hole structure provided by an embodiment of the present invention;

[0027] Figure 3 A circuit diagram containing nonlinear resistors and a schematic diagram of the corresponding voltage-current relationship in a system for regulating the vibration characteristics of an acoustic black hole structure provided by an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of the experimental test;

[0029] Figure 5 It is a schematic diagram of the low-frequency control effect of the controlled structure in the present invention;

[0030] Figure 6 It is a schematic diagram of the broadband control effect of the controlled structure in the present invention. DETAILED DESCRIPTION

[0031] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] Embodiment 1:

[0033] Example 1 provides a method for regulating the vibration characteristics of an acoustic black hole structure, see Figure 1An acoustic black hole structure 2 is additionally installed on the controlled structure 1, and the thickness of the acoustic black hole structure 2 changes according to a power law; a piezoelectric element 3 is attached to the acoustic black hole structure 2 to obtain a piezoelectric-acoustic black hole composite structure; the piezoelectric element 3 is connected to an external branch circuit 5, and the external branch circuit 5 is used to control the vibration characteristics of the piezoelectric-acoustic black hole composite structure.

[0034] See also Figure 2 , the external branch circuit 5 may include a capacitor, a resistor and an inductor connected in series. It should be noted that the external branch circuit 5 may also be other parallel or series circuits including capacitors, resistors and inductors. The nonlinear characteristics introduced by the external branch circuit 5 are used to adjust the vibration characteristics of the piezoelectric-acoustic black hole composite structure.

[0035] By adjusting at least one parameter among the capacitance value, the inductance value and the resistance value in the external branch circuit 5 , the vibration modal characteristics of the acoustic black hole structure 2 can be adjusted.

[0036] Embodiment 1 combines the piezoelectric element 3 with the acoustic black hole structure 2, and introduces nonlinear characteristics by controlling the external branch circuit 5, which can significantly improve the low-frequency vibration suppression performance of the acoustic black hole structure. Specifically, the piezoelectric element 3 (i.e., piezoelectric material) can change the acoustic black hole equivalent structural characteristics through electromechanical coupling with the acoustic black hole structure 2. The introduction of the nonlinear branch circuit (i.e., the external branch circuit 5) makes it easy for the additional acoustic black hole structure to produce a coupling characteristic effect of dynamic vibration absorption with the controlled structure, effectively improving the low-frequency vibration control capability, and realizing vibration suppression optimization within a wide frequency range.

[0037] The following is a detailed description of Example 1.

[0038] (1) Structural design and parameter optimization of piezoelectric-acoustic black hole composite structure.

[0039] Example 1 uses a wedge-shaped structure with acoustic black hole geometric characteristics as the basis. The wedge-shaped structure has energy gathering characteristics and can effectively concentrate high-frequency vibration energy. The thickness variation law of the acoustic black hole structure satisfies the power exponential variation: h(x) = ε(x-x0) m +h1. In the formula, h(x) is the thickness of the acoustic black hole structure, ε is the coefficient; h1 is the thickness of the thinnest area of ​​the acoustic black hole structure, that is, the thickness of the edge platform; x is the position coordinate of the acoustic black hole structure along the length direction of the unilateral central platform, x0 is the length of the unilateral central platform of the acoustic black hole structure; m is the power rate, which is generally greater than or equal to 2.

[0040] By optimizing the thickness variation curve of the acoustic black hole structure, it has good mid-high frequency energy gathering characteristics. By selecting appropriate materials and thickness configurations, it can be ensured that the acoustic black hole structure can achieve good vibration suppression effects while ensuring strength and rigidity.

[0041] The acoustic black hole structure is an additional acoustic black hole structure, which can be selected and designed according to the controlled structural characteristics and space limitations. The additional acoustic black hole structure can be designed as a one-dimensional beam structure, a two-dimensional spiral structure, a two-dimensional rectangular structure, a two-dimensional circular structure, etc.

[0042] In Example 1, piezoelectric elements are added to key locations of the acoustic black hole structure to ensure that the stress transfer efficiency between the piezoelectric element and the structure reaches an optimal state.

[0043] Among them, the strain information of the acoustic black hole structure can be obtained, and the laying position of the piezoelectric element on the acoustic black hole structure can be determined according to the strain information.

[0044] Specifically, a modal analysis is performed on the acoustic black hole structure to obtain modal analysis results including the natural frequency, vibration mode and response characteristics of the acoustic black hole structure in multiple modes, and strain information including the strain distribution of the acoustic black hole structure in multiple modes is calculated based on the modal analysis results of the acoustic black hole structure.

[0045] For example, the acoustic black hole structure is subjected to modal analysis by finite element analysis (FEA) or other numerical simulation methods to calculate the natural frequency and corresponding modal shape of the structure. During the simulation, the vibration characteristics under different working conditions are considered, especially the low-frequency vibration response. Alternatively, the actual displacement response u of the structure is measured by experimental testing using equipment such as accelerometers and displacement sensors. z (x, t), especially the vibration response in the key mode. Through the displacement data, the strain calculation formula is used Or the strain distribution of each point of the structure can be calculated by the post-processing tool of the finite element model. According to the strain information, the laying position of the piezoelectric element is determined. By analyzing the strain distribution at different frequencies, the best piezoelectric element setting position is selected to achieve the maximum piezoelectric effect.

[0046] The present invention obtains the vibration behavior and vibration characteristics of the acoustic black hole structure in different frequency bands through simulation or experiment, and pays special attention to the performance in the low-frequency range. For low-frequency vibrations, special attention is paid to areas with large displacement amplitudes. These areas will be greatly affected during the vibration process and have high energy absorption potential. According to the modal analysis results, the strain distribution of the acoustic black hole structure in different modes can be further calculated. The strain distribution can reflect the deformation of the structure in each frequency band. Especially in the low-frequency range, the strain distribution of the structure is usually uneven, and the strain in some parts is large, which means that these parts will bear more vibration energy. Therefore, through the strain data, it can be determined which areas are the best locations for installing the piezoelectric elements in order to maximize the piezoelectric effect.

[0047] By combining the geometric characteristics, vibration mode and strain data of the acoustic black hole structure, the piezoelectric element is laid at a position that can produce the greatest effect during the vibration process, which helps to obtain a better vibration control effect. The piezoelectric element needs to be installed at a position with large strain and more significant vibration displacement, so that the electromechanical coupling coefficient can be higher during the vibration process, thereby effectively absorbing the vibration energy and playing a role in suppressing vibration. Therefore, when the external circuit is disconnected, the electromechanical coupling equation of the piezoelectric-acoustic black hole composite structure is as follows:

[0048]

[0049] Θ T a+C p V p +q=0

[0050] Among them, M is the mass matrix of the piezoelectric-acoustic black hole composite structure, K is the stiffness matrix and of the piezoelectric-acoustic black hole composite structure, a is the discretized generalized coordinate of the mechanical system, is the second-order derivative of the discretized generalized coordinates of the mechanical system, Θ is the electromechanical coupling coefficient, and f is the external excitation force vector; Θ T is the transpose of the electromechanical coupling coefficient, C p is the capacitance of the piezoelectric element, V p is the voltage value across the piezoelectric element, and q is the charge.

[0051] In addition, the thickness, size and installation method (such as the surface facing the acoustic black hole structure or embedded in the acoustic black hole structure) of the piezoelectric element (such as a piezoelectric sheet) may affect its vibration control effect, so it is necessary to comprehensively consider these factors for optimization design. Considering that the piezoelectric element is mainly attached by AB glue for firm adhesion, the optimization effect of the piezoelectric element laying position can be verified in advance through numerical simulation. Simulation can simulate the coupling effect between the piezoelectric element and the acoustic black hole structure through finite element analysis software to ensure the working efficiency of the piezoelectric element at the selected position. Experimental testing can actually test the structure through a vibration table or other equipment to verify the vibration suppression effect of the piezoelectric element at a predetermined position. Further adjust the position of the piezoelectric element according to the simulation and experimental results to ensure that it can play its role to the greatest extent during the vibration process.

[0052] In addition, see Figure 1 A damping element 4 may also be provided on the acoustic black hole structure, that is, damping material may be added to the acoustic black hole structure 2 to further optimize the vibration control effect.

[0053] (2) Design of external branch circuit.

[0054] The external branch circuit may include a capacitor, a resistor and an inductor connected in series; the external branch circuit is used to introduce nonlinear characteristics to adjust the vibration characteristics of the piezoelectric-acoustic black hole composite structure.

[0055] Example 1 designs an external branch circuit that matches the piezoelectric element, and dynamically adjusts the vibration modal characteristics of the piezoelectric-acoustic black hole composite structure by introducing nonlinear characteristics, ensuring that the low-frequency band of the piezoelectric-acoustic black hole composite structure and the controlled structure achieve efficient dynamic vibration absorption effect.

[0056] First, a basic circuit structure is constructed. The circuit can dynamically adjust the parameters of different components in the circuit according to the vibration response of the acoustic black hole structure to control the performance of the piezoelectric element. Figure 2 The components present in the external branch circuit are shown, among which the capacitor ( Figure 2 C in), resistance ( Figure 2 R n ),inductance( Figure 2 The L) elements in the diagram can introduce nonlinear characteristics. Figure 2 The "Piezo" in this example represents a piezoelectric element. Figure 2 The circuit voltage equation in is as follows:

[0057]

[0058] In the above formula, v(t) is the voltage across the piezoelectric element, L is the inductance in the external branch circuit, R is the resistance in the external branch circuit, C is the capacitance in the external branch circuit, q(t) is the charge in the circuit (specifically, the change in charge over time), is the first-order derivative of the charge in the circuit, is the second derivative of the charge in the circuit.

[0059] According to the principle of minimum potential energy, the Lagrangian equation of the electromechanical coupling system including the piezoelectric-acoustic black hole composite structure and the external branch circuit is constructed as follows:

[0060]

[0061] Where M is the mass matrix of the piezoelectric-acoustic black hole composite structure (i.e., the mechanical system), Figure 1 For example, in the case of setting a damping element, M is specifically composed of the mass of the acoustic black hole structure 2, the mass of the piezoelectric element 3, and the mass of the damping structure 4; L is the inductance in the external branch circuit, R is the resistance in the external branch circuit, and C is the capacitance in the external branch circuit; K is the stiffness matrix of the mechanical system, Figure 1 For example, K is specifically composed of the stiffness of the acoustic black hole structure 2, the stiffness of the piezoelectric element 3, and the stiffness of the damping structure 4; image(K) is the imaginary part of the stiffness matrix, real(K) is the real part of the stiffness matrix, ω is the external excitation frequency, f ext (t) is the external excitation, a(t) is the discretized generalized coordinate of the mechanical system, a(t) is also the weight coefficient of the displacement shape function in the mechanical system, and is the part to be solved in the Lagrangian energy equation for constructing the electromechanical coupling system, which can be solved by the semi-analytical method; is the first-order derivative of the discretized generalized coordinates of the mechanical system, is the second-order derivative of the discretized generalized coordinates of the mechanical system; q(t) is the charge; is the first-order derivative of the charge, and V p The function of R, that is V p is the voltage value across the piezoelectric element; is the second-order derivative of the charge; Θ is the electromechanical coupling coefficient, Θ T is the transpose of the electromechanical coupling coefficient, C p is the capacitance of the piezoelectric element, C p -1 It is the reciprocal of the capacitance of the piezoelectric element.

[0062] Since the inductance, resistance, and capacitance in the circuit system can be equivalent to the mass, damping, and stiffness in the mechanical system, respectively, the Lagrange equation of the electromechanical coupling system can be used to illustrate how the present invention dynamically adjusts the vibration characteristics of the acoustic black hole structure by adjusting at least one parameter among the capacitance value, inductance value, and resistance value in the external branch circuit.

[0063] The present invention adjusts the values ​​of components such as capacitors, inductors, resistors, etc. in the external branch circuit, and can adjust the vibration characteristics of the piezoelectric-acoustic black hole composite structure. The purpose of general circuit design is to effectively control the vibration characteristics of the structure by accurately adjusting the parameters of the piezoelectric branch circuit components, so that it can exert a vibration absorption effect at a specific vibration frequency. The introduction of nonlinear circuit characteristics in the present invention is to enhance the dynamic vibration absorption ability of piezoelectric materials during low-frequency vibrations. The branch circuit characteristics can be dynamically adjusted in the present invention, thereby introducing nonlinear characteristics into the system. When the acoustic black hole structure is subjected to external excitation, charges are generated at both ends of the piezoelectric element, and the voltage of the external branch circuit changes accordingly. The voltage at both ends of the piezoelectric element will also change accordingly, thereby affecting the electric field strength and structural characteristics of the piezoelectric element.

[0064] like Figure 3 As shown, nonlinear characteristics can be introduced by resistor components. Specifically, the structural characteristics of the piezoelectric element change with the change of the electric field strength. Therefore, by adjusting the component parameters in the external branch circuit, the voltage of the piezoelectric branch circuit is changed, thereby changing the piezoelectric-acoustic black hole composite structural characteristics.

[0065] Specifically, the working principle of nonlinear regulation is: the circuit parameters change, changing the response mode of the piezoelectric element. Under low-frequency vibration, increasing the nonlinear regulation effect of the branch can make the piezoelectric element produce a stronger reverse force, thereby improving its ability to absorb low-frequency vibration. This nonlinear effect changes the effective stiffness of the material, giving the acoustic black hole structure a stronger vibration suppression ability. Unlike linear systems, nonlinear characteristics can show different responses under different vibration amplitudes, which enables the acoustic black hole structure to be effectively adjusted in both low-frequency and high-frequency ranges.

[0066] During the design process, the parameter adjustment of the control circuit is very critical. For example, first, according to the results of the modal analysis, by adjusting the capacitance and voltage range in the circuit, the piezoelectric element can change dynamically within the required frequency band. The nonlinear stiffness characteristics can be introduced by adjusting the variable capacitance value of the external branch circuit to control the vibration modal characteristics of the piezoelectric-acoustic black hole composite structure. In the low-frequency range, the nonlinear adjustment of the external branch circuit can enhance the vibration absorption characteristics of the piezoelectric element. By adjusting the circuit parameters to adapt to the vibration energy distribution in different frequency bands, it is ensured that the dynamic vibration absorption characteristics are exerted in the low-frequency range.

[0067] In addition, Example 1 can also perform modal analysis and / or vibration characteristic testing on the overall vibration control system (including an acoustic black hole structure and a piezoelectric control unit, the piezoelectric control unit includes a piezoelectric element and an external branch circuit), and optimize control parameters and / or verify the vibration control effect based on the obtained modal analysis results and vibration characteristic test results, wherein the control parameters include the capacitance value, inductance value and resistance value in the external branch circuit.

[0068] See also Figure 4 , when conducting experimental verification, the acoustic black hole structure 2 after design optimization and the piezoelectric element 3 are precisely assembled together through AB glue to ensure that the piezoelectric element 3 is laid in an area with greater strain to maximize the piezoelectric effect. Then, the designed nonlinear control circuit (i.e., the external branch circuit 5) is connected to the piezoelectric element 3 to construct a complete vibration control system. Of course, a damping element 4 can also be set on the acoustic black hole structure 2. In this process, special attention should be paid to the following points: ensure close contact between the piezoelectric element 3 and the surface of the acoustic black hole structure 2, and eliminate looseness or stress concentration during installation by bonding or other fixing methods. The connection of the nonlinear control circuit must be firm and avoid the influence of external electromagnetic interference on the circuit performance. The integration of the structure of each component should take into account the space in the actual experimental test, while ensuring its reliability and vibration resistance.

[0069] Experimental test preparation Install the integrated system on the vibration table equipment (such as the exciter). The test equipment must have adjustable frequency and controllable amplitude functions to simulate the vibration environment of different working conditions. According to the test requirements, select the appropriate vibration frequency band and loading conditions, focusing on the vibration control effect in the low-frequency and wide-frequency range. Modal analysis and performance verification Use the experimental equipment to perform modal analysis and vibration testing on the system to specifically verify the following:

[0070] Modal frequency and vibration mode: Analyze the response characteristics of the system under different modal orders, especially the dynamic vibration absorption effect of low-frequency modes and the energy aggregation ability of medium and high-frequency modes.

[0071] Low-frequency vibration suppression effect: The vibration amplitude and frequency response function (FRF) of the system in each frequency band are measured by test equipment to evaluate the contribution of the nonlinear regulation performance of the external circuit to vibration suppression. Energy distribution characteristics: Focus on observing whether the energy of high-frequency vibration is concentrated in the key area of ​​the acoustic black hole structure to verify whether its energy-gathering effect meets the design requirements.

[0072] System parameter experimental test: Adjust the nonlinear adjustment parameters of the external branch circuit to ensure that it can provide sufficient dynamic vibration absorption in the low-frequency range, while maintaining good vibration response in the medium and high-frequency range. Optimize the laying position and coverage area of ​​the piezoelectric element, and adjust its installation position according to experimental feedback to maximize the vibration energy absorption effect.

[0073] After the test is completed, it can also be applied to actual working conditions to evaluate its comprehensive performance: the system can be installed on equipment or structures in complex vibration environments, such as Figure 4 The plate structure shown (i.e. the plate structure is used as the controlled structure 1) is tested to simulate actual operating conditions. The vibration suppression effect of the system in a wide frequency range is recorded, including low-frequency vibration absorption capacity and wide-frequency vibration control effect. Figure 5 It is a schematic diagram of the low-frequency control effect of the controlled structure. Figure 6 It is a schematic diagram of the broadband control effect of the controlled structure. It can be seen that the present invention enhances the dynamic vibration absorption effect in the low frequency band by adding an external branch circuit, and achieves a good broadband vibration suppression effect. In addition, the long-term stability and reliability of the system can also be checked, and its durability performance in complex environments can be evaluated.

[0074] In summary, the method for regulating the vibration characteristics of the acoustic black hole structure provided in Example 1 changes the characteristics of the acoustic black hole structure through an external branch circuit connected to the piezoelectric-acoustic black hole composite structure, so that the acoustic black hole structure exhibits a stronger dynamic vibration absorption ability in the low-frequency range, and can equivalently regulate the low-frequency vibration characteristics of the acoustic black hole structure. Example 1 introduces a nonlinear mechanism to meet the needs of complex environments. By controlling the adjustable parameters of the external branch circuit, it can flexibly adapt to different vibration frequencies and working conditions, improve the scope of application and efficiency, and has the advantages of strong adaptability and flexibility. It can achieve efficient energy regulation and multi-band vibration control, achieve broadband vibration suppression, and achieve efficient vibration reduction and noise reduction in a wide frequency range. In addition, without increasing the weight, Example 1 takes into account the advantages of active control and passive control, and has the advantages of lightweight structure and optimized functions.

[0075] Embodiment 2:

[0076] Embodiment 2 provides a system for regulating the vibration characteristics of an acoustic black hole structure, comprising: an acoustic black hole structure and a piezoelectric control unit; the acoustic black hole structure is additionally installed on a controlled structure, and the thickness of the acoustic black hole structure varies according to a power law; the piezoelectric control unit comprises a piezoelectric element attached to the acoustic black hole structure, and an external branch circuit connected to the piezoelectric element.

[0077] The system for regulating the vibration characteristics of an acoustic black hole structure provided in Example 2 is used to execute the method for regulating the vibration characteristics of an acoustic black hole structure as described in Example 1.

[0078] Since the characteristics or functions of each structure or circuit in the system provided in Example 2 correspond to the limitations in the method provided in Example 1, Example 2 can be understood by referring to the description of Example 1, which will not be repeated here.

[0079] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for regulating the vibration characteristics of an acoustic black hole structure, characterized in that: An acoustic black hole structure is additionally installed on a controlled structure, and the thickness of the acoustic black hole structure changes according to a power law; a piezoelectric element is attached to the acoustic black hole structure to obtain a piezoelectric-acoustic black hole composite structure; the piezoelectric element is connected to an external branch circuit, and the vibration characteristics of the piezoelectric-acoustic black hole composite structure are regulated by using the external branch circuit.

2. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 1, characterized in that: The external branch circuit includes a capacitor, a resistor and an inductor connected in series or in parallel; the external branch circuit is used to introduce nonlinear characteristics to adjust the vibration characteristics of the acoustic black hole structure.

3. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 2, characterized in that: By adjusting at least one parameter among the capacitance value, inductance value and resistance value in the external branch circuit, the vibration characteristics of the acoustic black hole structure are dynamically adjusted to achieve effective coupling of the vibration modal characteristics of the acoustic black hole structure and the controlled structure.

4. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 3, characterized in that: The expression of the displacement response w(x, t) of the acoustic black hole structure is set as: in, is the shape function of the acoustic black hole structure displacement; a(t) is the weight coefficient of the corresponding shape function, which is also the discretized generalized coordinate; According to the principle of minimum potential energy, the Lagrangian equation of the electromechanical coupling system including the piezoelectric-acoustic black hole composite structure and the external branch circuit is constructed as follows: Where M is the mass matrix of the piezoelectric-acoustic black hole composite structure, L is the inductance in the external branch circuit, R is the resistance in the external branch circuit, C is the capacitance in the external branch circuit, K is the stiffness matrix of the piezoelectric-acoustic black hole composite structure, image(K) is the imaginary part of the stiffness matrix, real(K) is the real part of the stiffness matrix, ω is the external excitation frequency, and f ext (t) is the external stimulus, is the first-order derivative of the discretized generalized coordinates, is the second-order derivative of the discretized generalized coordinates; q(t) is the charge; is the first-order derivative of the charge, and V p The function of R, that is V p is the voltage value across the piezoelectric element; is the second-order derivative of the charge; Θ is the electromechanical coupling coefficient, Θ T is the transpose of the electromechanical coupling coefficient; C p is the capacitance of the piezoelectric element, C p -1 It is the reciprocal of the capacitance of the piezoelectric element.

5. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 2, characterized in that: Performing modal analysis and vibration characteristic regulation test on the electromechanical coupling system including the piezoelectric-acoustic black hole composite structure and the external branch circuit; According to the modal analysis results and vibration characteristic regulation test results of the electromechanical coupling system, the control parameters are optimized; the control parameters include the capacitance value, inductance value and resistance value in the external branch circuit.

6. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 1, characterized in that: The strain information of the acoustic black hole structure is acquired, and the setting position of the piezoelectric element on the acoustic black hole structure is determined according to the strain information.

7. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 6, characterized in that: A modal analysis is performed on the acoustic black hole structure to obtain modal analysis results including the natural frequency, vibration mode and response characteristics of the acoustic black hole structure in multiple modes, and strain information including the strain distribution of the acoustic black hole structure in multiple modes is calculated based on the modal analysis results of the acoustic black hole structure.

8. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 1, characterized in that: Also includes: A damping element is arranged on the acoustic black hole structure.

9. The method for regulating the vibration characteristics of an acoustic black hole structure according to claim 1, characterized in that: The acoustic black hole structure is an additional acoustic black hole structure, and the additional acoustic black hole structure is designed as a one-dimensional beam structure, a two-dimensional spiral structure, a two-dimensional rectangular structure or a two-dimensional circular structure.

10. A system for regulating the vibration characteristics of an acoustic black hole structure, characterized in that: include: Acoustic black hole structure and piezoelectric control unit; The acoustic black hole structure is additionally installed on the controlled structure, and the thickness of the acoustic black hole structure changes according to a power exponential law; The piezoelectric control unit includes a piezoelectric element attached to the acoustic black hole structure, and an external branch circuit connected to the piezoelectric element; The system for regulating the vibration characteristics of an acoustic black hole structure is used to execute the method for regulating the vibration characteristics of an acoustic black hole structure as described in any one of claims 1-9.

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