A method and system for regulating the vibration characteristics of an acoustic black hole structure

Abstract

This invention belongs to the field of vibration control technology and discloses a method and system for regulating the vibration characteristics of an acoustic black hole structure. In this invention, the acoustic black hole structure is attached to the controlled structure, and the thickness of the acoustic black hole structure varies according to a 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 using the external branch circuit. This invention can optimize the low-frequency vibration suppression performance of the acoustic black hole structure and achieve efficient vibration control over a wide frequency range.

Description

Technical Field

[0001] This 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 Technology

[0002] With the rapid development of industrial equipment and aerospace technology, vibration control technology has become a key area for improving structural performance and reliability. Acoustic black hole (ABH) structures, due to their energy concentration characteristics, perform excellently in mid- and high-frequency vibration control, but they are insufficient in low-frequency vibration suppression, which limits their application potential in broadband vibration control.

[0003] Currently, acoustic black hole structures are in the development stage, and their application in complex vibration environments still faces challenges. Therefore, there is an urgent need for an innovative technical solution to further improve the low-frequency and broadband vibration control capabilities of acoustic black hole structures and expand their practical application scenarios in high-performance structures. Summary of the Invention

[0004] This invention provides a method and system for regulating the vibration characteristics of acoustic black hole structures, thereby addressing the problem that the low-frequency and broadband vibration control capabilities of acoustic black hole structures in the prior art need further improvement.

[0005] This invention provides a method for controlling the vibration characteristics of an acoustic black hole structure. The acoustic black hole structure is attached to a controlled structure, and the thickness of the acoustic black hole structure varies 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 controlled by the external branch circuit.

[0006] Preferably, the external branch circuit includes capacitors, resistors, and inductors connected in series / parallel; the external branch circuit is used to introduce nonlinear characteristics to adjust the vibration characteristics of the acoustic black hole structure.

[0007] Preferably, the vibration characteristics of the acoustic black hole structure are dynamically adjusted by adjusting at least one parameter among the capacitance, inductance, and resistance values ​​in the external branch circuit, thereby achieving effective coupling between the vibration modal characteristics of the acoustic black hole structure and the controlled structure.

[0008] Preferably, the acoustic black hole structure displacement response is set. The expression is: ;in, The shape function of the structural displacement of the acoustic black hole; These are the weighting coefficients of the corresponding shape function, and also the discretized generalized coordinates;

[0009] Based on the principle of minimum potential energy, the Lagrange equations for the electromechanical coupling system comprising the piezoelectric-acoustic black hole composite structure and the external branch circuit are as follows:

[0010]

[0011] In the formula, M is the mass matrix of the piezoelectric-acoustic black hole composite structure, L is the inductance of the external branch circuit, R is the resistance of the external branch circuit, C is the capacitance of the external branch circuit, and K is the stiffness matrix of the piezoelectric-acoustic black hole composite structure. This is the imaginary part of the stiffness matrix. Let be the real part of the stiffness matrix. For external excitation frequency, As an external incentive, The first derivative of the discretized generalized coordinates, The second derivative of the discretized generalized coordinates; It is the charge; Let be the first derivative of the charge, and for Functions of R, i.e. , This represents the voltage across the piezoelectric element. The second derivative of the charge; The electromechanical coupling coefficient is... This is the transpose of the electromechanical coupling coefficient; For the capacitance of a piezoelectric element, It is the reciprocal of the capacitance of the piezoelectric element.

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

[0013] Based on the modal analysis results and vibration characteristic control test results of the electromechanical coupling system, the control parameters are optimized; the control parameters include the capacitance, inductance and resistance values ​​in the external branch circuit.

[0014] Preferably, strain information of the acoustic black hole structure is obtained, and the placement position of the piezoelectric element on the acoustic black hole structure is determined based on the strain information.

[0015] Preferably, modal analysis is performed on the acoustic black hole structure to obtain modal analysis results containing the natural frequencies, mode shapes, and response characteristics of the acoustic black hole structure in multiple modes. Based on the modal analysis results of the acoustic black hole structure, strain information containing the strain distribution of the acoustic black hole structure in multiple modes is calculated.

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

[0017] Preferably, the acoustic black hole structure is an additional acoustic black hole structure, which 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 attached to the controlled structure, and the thickness of the acoustic black hole structure varies according to a power 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.

[0019] The system for regulating the vibration characteristics of an acoustic black hole structure is used to perform the aforementioned method for regulating the vibration characteristics of an acoustic black hole structure.

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

[0021] In this invention, an acoustic black hole structure is attached to a controlled structure. The thickness of the acoustic black hole structure varies according to a 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, which is used to regulate the vibration characteristics of the piezoelectric-acoustic black hole composite structure. This invention utilizes a dynamically adjustable external branch circuit to introduce nonlinear characteristics, enabling dynamic adjustment of the piezoelectric branch circuit characteristics. This allows for adjustment of the dynamic response of the piezoelectric element, achieving the modal characteristic regulation of the acoustic black hole structure. Consequently, the vibration characteristics of the piezoelectric-acoustic black hole composite structure can be controlled, significantly improving the controllability of the low-order modes of the acoustic black hole structure and enhancing the ability to regulate low-frequency vibration coupling characteristics. This results in the acoustic black hole structure exhibiting strong adaptability and flexibility in low-frequency vibration regulation.

[0022] This invention utilizes the nonlinear characteristics of external branch circuits to not only optimize low-frequency dynamic vibration absorption control in acoustic black hole structures, but also achieve comprehensive control from low to high frequencies by combining nonlinear circuit parameter adjustment. Furthermore, the adjustment method is flexible and can adapt to various operating conditions. This invention combines the mid-to-high frequency energy concentration of acoustic black holes with the low-frequency control of dynamic vibration absorption to meet the needs of wideband vibration control. Through multimodal control, it can achieve wideband vibration suppression, with a wide control range and strong adaptability, meeting the requirements of complex vibration conditions without introducing complex additional structures such as arrays into the control system.

[0023] In summary, this invention enhances the dynamic vibration absorption effect of the acoustic black hole in the low-frequency range and optimizes the low-frequency vibration suppression performance of the acoustic black hole structure by synergistically combining the introduced piezoelectric nonlinear characteristics with the acoustic black hole structure. Simultaneously, the acoustic black hole structure's efficient absorption and dissipation of wave energy in the high-frequency range enables highly efficient vibration suppression of the controlled structure over a wide frequency range.

[0024] Furthermore, this invention determines the placement of piezoelectric elements on the acoustic black hole structure based on strain information, maximizing the piezoelectric effect and thus achieving better vibration control. This invention can also incorporate damping elements on the acoustic black hole structure; these damping elements efficiently dissipate the mechanical vibration energy of the acoustic black hole structure, further optimizing vibration control. This invention also improves the integration of the vibration control system, reduces system complexity, and enhances vibration control efficiency. Attached Figure Description

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

[0027] Figure 3 A circuit diagram containing a nonlinear resistor 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 in an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the experimental test;

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

[0030] Figure 6 This is a schematic diagram illustrating the broadband control effect of the controlled structure in this invention. Detailed Implementation

[0031] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0032] Example 1:

[0033] Example 1 provides a method for controlling the vibration characteristics of an acoustic black hole structure, see [link to example]. Figure 1An acoustic black hole structure 2 is attached to the controlled structure 1, and the thickness of the acoustic black hole structure 2 varies 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 vibration characteristics of the piezoelectric-acoustic black hole composite structure are controlled by the external branch circuit 5.

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

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

[0036] Example 1 combines the piezoelectric element 3 with the acoustic black hole structure 2. By controlling the external branch circuit 5 to introduce nonlinear characteristics, the low-frequency vibration suppression performance of the acoustic black hole structure can be significantly improved. Specifically, the piezoelectric element 3 (i.e., piezoelectric material) can change the equivalent structural characteristics of the acoustic black hole 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 easier for the additional acoustic black hole structure to generate dynamic vibration absorption coupling characteristics with the controlled structure, effectively improving the low-frequency vibration control capability and achieving vibration suppression optimization over 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 the geometric characteristics of an acoustic black hole as its foundation. The wedge-shaped structure possesses energy-concentrating properties, effectively focusing high-frequency vibrational energy. The thickness variation of the acoustic black hole structure follows a power-law variation: In the formula, The thickness of the acoustic black hole structure. For coefficients; This refers to the thickness of the thinnest region of the acoustic black hole structure, i.e., the thickness of the edge plateau. Let be the position coordinates of the acoustic black hole structure along the length of its single-sided central platform. The length of the single-sided central platform of the acoustic black hole structure; It is a power law, generally greater than or equal to 2.

[0040] By optimizing the thickness variation curve of the acoustic black hole structure, it can be made to possess good mid-to-high frequency energy concentration characteristics. By selecting appropriate materials and thickness configurations, it can be ensured that the acoustic black hole structure can achieve good vibration suppression while maintaining strength and stiffness.

[0041] The acoustic black hole structure is an additional acoustic black hole structure. The acoustic black hole structure can be designed according to the characteristics of the controlled structure and spatial constraints. 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] Example 1 involves adding piezoelectric elements to key parts of the acoustic black hole structure to ensure that the stress transfer efficiency between the elements and the structure reaches the optimal state.

[0043] Among these methods, strain information of the acoustic black hole structure can be obtained, and the placement position of the piezoelectric element on the acoustic black hole structure can be determined based on the strain information.

[0044] Specifically, modal analysis is performed on the acoustic black hole structure to obtain modal analysis results containing the natural frequencies, mode shapes, and response characteristics of the acoustic black hole structure in multiple modes. Based on the modal analysis results of the acoustic black hole structure, strain information containing the strain distribution of the acoustic black hole structure in multiple modes is calculated.

[0045] For example, modal analysis can be performed on the acoustic black hole structure using finite element analysis (FEA) or other numerical simulation methods to calculate the structure's natural frequencies and corresponding modal shapes. During the simulation, vibration characteristics under different operating conditions, especially low-frequency vibration responses, should be considered. Alternatively, experimental testing can be conducted using devices such as accelerometers and displacement sensors to measure the actual displacement response of the structure. Especially the vibration response under key modes. Using displacement data, strain calculation formulas are employed. Alternatively, the strain distribution at various points on the structure can be calculated using post-processing tools for the finite element model. Based on the strain information, the placement location of the piezoelectric element can be determined. By analyzing the strain distribution at different frequencies, the optimal placement location of the piezoelectric element can be selected to maximize the piezoelectric effect.

[0046] This invention obtains the vibration behavior and characteristics of the acoustic black hole structure in different frequency bands through simulation or experiment, with particular focus on its performance in the low-frequency range. For low-frequency vibration, special attention is paid to regions with large displacement amplitudes, as these regions are significantly affected during vibration and have high energy absorption potential. Based on the modal analysis results, the strain distribution of the acoustic black hole structure under different modes can be further calculated. The strain distribution reflects the deformation of the structure in each frequency band. Especially in the low-frequency range, the strain distribution of the structure is usually non-uniform, with larger strains in some parts, meaning that these parts will bear more vibration energy. Therefore, through strain data, the optimal installation positions of the piezoelectric element can be determined to maximize the piezoelectric effect.

[0047] By combining the geometric characteristics, vibration modes, and strain data of the acoustic black hole structure, the piezoelectric element is placed at the location that produces the maximum effect during vibration, thus contributing to better vibration control. The piezoelectric element needs to be installed at locations with large strain and significant vibration displacement to achieve a higher electromechanical coupling coefficient during vibration, thereby effectively absorbing vibration energy and suppressing vibration. Therefore, with the external circuit disconnected, the electromechanical coupling equation of the piezoelectric-acoustic black hole composite structure is as follows:

[0048]

[0049] Where M is the mass matrix of the piezoelectric-acoustic black hole composite structure, and K is the stiffness matrix of the piezoelectric-acoustic black hole composite structure. For the discretization of the mechanical system, generalized coordinates For the second derivative of the discretized generalized coordinates of the mechanical system, is the electromechanical coupling coefficient, and f is the external excitation force vector; The transpose of the electromechanical coupling coefficient. For the capacitance of a piezoelectric element, The voltage across the piezoelectric element. This represents the amount of charge.

[0050] Furthermore, the thickness, size, and installation method of the piezoelectric element (e.g., piezoelectric sheet) (such as facing the surface of the acoustic black hole structure or embedding it inside the acoustic black hole structure) can all affect its vibration control effect. Therefore, these factors need to be comprehensively considered for optimized design. Considering that the piezoelectric element is mainly attached by firmly bonding with AB glue, the optimized placement of the piezoelectric element can be verified in advance through numerical simulation. The simulation can use finite element analysis software to simulate the coupling effect between the piezoelectric element and the acoustic black hole structure, ensuring the working efficiency of the piezoelectric element at the selected location. Experimental testing can be conducted on the structure using a vibration table or other equipment to verify the vibration suppression effect of the piezoelectric element at the predetermined location. Based on the simulation and experimental results, the position of the piezoelectric element can be further adjusted to ensure that it can play a maximum role during vibration.

[0051] In addition, see Figure 1 Furthermore, a damping element 4 can be installed on the acoustic black hole structure, that is, damping material is added to the acoustic black hole structure 2 to further optimize the vibration control effect.

[0052] (2) Design of external branch circuits.

[0053] The external branch circuit may include a capacitor, a resistor, and an inductor connected in series; the nonlinear characteristics introduced by the external branch circuit are used to adjust the vibration characteristics of the piezoelectric-acoustic black hole composite structure.

[0054] Example 1 designs an external branch circuit to match the piezoelectric element. By introducing nonlinear characteristics, the vibration mode characteristics of the piezoelectric-acoustic black hole composite structure are dynamically adjusted to ensure that the low-frequency band of the piezoelectric-acoustic black hole composite structure and the controlled structure achieve efficient dynamic vibration absorption.

[0055] First, a basic circuit structure is built. This circuit can dynamically adjust the parameters of different components in the circuit according to the vibration response of the acoustic black hole structure, thereby controlling the performance of the piezoelectric element. Figure 2 The components present in the external branch circuit are shown, including capacitors ( Figure 2 C in the middle), resistance ( Figure 2 R in n ),inductance( Figure 2 The L-elements in the model can all be introduced with nonlinear characteristics. Figure 2 In this context, Piezo represents a piezoelectric element. Figure 2 The circuit voltage equations are as follows:

[0056]

[0057] In the above formula, Let L be the voltage across the piezoelectric element, L be the inductance in the external branch circuit, R be the resistance in the external branch circuit, and C be the capacitance in the external branch circuit. This refers to the charge in the circuit (specifically, the change in charge quantity over time). The first derivative of the charge in the circuit. It is the second derivative of the charge in the circuit.

[0058] Based on the principle of minimum potential energy, the Lagrange equations for the electromechanical coupling system comprising the piezoelectric-acoustic black hole composite structure and the external branch circuit are as follows:

[0059]

[0060] In the formula, M is the mass matrix of the piezoelectric-acoustic black hole composite structure (i.e., the mechanical system), with... Figure 1 For example, when a damping element is set, M is specifically composed of the sum of the mass of the acoustic black hole structure 2, the mass of the piezoelectric element 3, and the mass of the damping element 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, with... Figure 1 For example, K is specifically composed of the sum of the stiffness of the acoustic black hole structure 2, the stiffness of the piezoelectric element 3, and the stiffness of the damping element 4; This is the imaginary part of the stiffness matrix. Let be the real part of the stiffness matrix. For external excitation frequency, As an external incentive, For the discretization of the mechanical system, generalized coordinates It is also the weighting coefficient of the displacement shape function in the mechanical system, and is the part to be solved in the Lagrange energy equation of the electromechanical coupled system, which can be solved by the semi-analytical method; The first derivative of the discretized generalized coordinates of the mechanical system. The second derivative of the discretized generalized coordinates of the mechanical system; It is the charge; Let be the first derivative of the charge, and for Functions of R, i.e. , This represents the voltage across the piezoelectric element. The second derivative of the charge; The electromechanical coupling coefficient is... The transpose of the electromechanical coupling coefficient. For the capacitance of a piezoelectric element, It is the reciprocal of the capacitance of the piezoelectric element.

[0061] Since the inductance, resistance, and capacitance in a circuit system can be equivalent to the mass, damping, and stiffness in a mechanical system, respectively, the Lagrange equation for the electromechanical coupling system described above can be used to explain how the present invention dynamically adjusts the vibration characteristics of the acoustic black hole structure by adjusting at least one parameter among the capacitance, inductance, and resistance values ​​in the external branch circuit.

[0062] This invention allows adjustment of the values ​​of components such as capacitors, inductors, and resistors in the external branch circuit to modify the vibration characteristics of the piezoelectric-acoustic black hole composite structure. The general purpose of circuit design is to effectively control the vibration characteristics of the structure by precisely adjusting the parameters of the piezoelectric branch circuit components, enabling it to exert a vibration absorption effect at a specific vibration frequency. The introduction of nonlinear circuit characteristics in this invention enhances the dynamic vibration absorption capability of the piezoelectric material at low frequencies. This invention allows for dynamic adjustment of the branch circuit characteristics, thereby introducing nonlinear characteristics into the system. When the acoustic black hole structure is subjected to external excitation, charges are generated at the ends of the piezoelectric element, causing a change in the voltage of the external branch circuit. This change in voltage across the piezoelectric element also affects the electric field strength and structural characteristics of the piezoelectric element.

[0063] like Figure 3 As shown, nonlinear characteristics can be introduced by resistive components. Specifically, the structural characteristics of the piezoelectric element change with the change of electric field strength. Therefore, by adjusting the component parameters in the external branch circuit to change the voltage of the piezoelectric branch circuit, the characteristics of the piezoelectric-acoustic black hole composite structure can be altered.

[0064] Specifically, the working principle of nonlinear adjustment is as follows: changes in circuit parameters alter the response of the piezoelectric element. Under low-frequency vibrations, increasing the nonlinear adjustment of the branch can generate a stronger counterforce in the piezoelectric element, thereby improving its absorption capacity for low-frequency vibrations. This nonlinear effect, by changing the effective stiffness of the material, gives the acoustic black hole structure a stronger vibration suppression capability. Unlike linear systems, nonlinear characteristics exhibit different responses at different vibration amplitudes, allowing the acoustic black hole structure to be effectively adjusted in both low-frequency and high-frequency ranges.

[0065] In the design process, parameter adjustment of the control circuit is crucial. For example, based on the results of modal analysis, the capacitance and voltage range in the circuit are adjusted to allow the piezoelectric element to dynamically change within the required frequency range. Nonlinear stiffness characteristics can be introduced by adjusting the variable capacitance value of the external branch circuit, thereby controlling 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, dynamic vibration absorption characteristics are ensured in the low-frequency range.

[0066] In addition, Embodiment 1 can also perform modal analysis and / or vibration characteristic testing on the overall vibration control system (including the acoustic black hole structure and the piezoelectric control unit, which includes piezoelectric elements and external branch circuits). Based on the obtained modal analysis results and vibration characteristic test results, the control parameters can be optimized and / or the vibration control effect can be verified. The control parameters include the capacitance, inductance and resistance values ​​in the external branch circuit.

[0067] See Figure 4 During experimental verification, the optimized acoustic black hole structure 2 and the piezoelectric element 3 are precisely assembled together using AB glue, ensuring that the piezoelectric element 3 is placed in areas of high strain to maximize the piezoelectric effect. Next, the designed nonlinear control circuit (i.e., external branch circuit 5) is connected to the piezoelectric element 3 to construct a complete vibration control system. Damping elements 4 can also be installed on the acoustic black hole structure 2. In this process, the following points require special attention: ensuring tight contact between the piezoelectric element 3 and the surface of the acoustic black hole structure 2, eliminating loosening or stress concentration during installation through bonding or other fixing methods; ensuring the connection of the nonlinear control circuit is secure and avoiding the influence of external electromagnetic interference on circuit performance; and considering the space available in actual experimental testing while ensuring its reliability and vibration resistance.

[0068] Experimental Testing Preparation: The integrated system is installed on a vibration table (e.g., a vibrator). The testing equipment must have adjustable frequency and controllable amplitude to simulate vibration environments under different working conditions. Based on the testing requirements, appropriate frequency bands and loading conditions are selected, with a focus on vibration control effects in the low-frequency and wide-frequency ranges. Modal Analysis and Performance Verification: Modal analysis and vibration testing are performed on the system using experimental equipment to specifically verify the following:

[0069] Modal frequencies and vibration modes: Analyze the response characteristics of the system under different modes, especially the dynamic vibration absorption effect of low-frequency modes and the energy accumulation capability of mid- and high-frequency modes.

[0070] Low-frequency vibration suppression effect: The vibration amplitude and frequency response function (FRF) of the system in each frequency band are measured using testing equipment to evaluate the contribution of the nonlinear adjustment performance of the external circuit to vibration suppression. Energy distribution characteristics: The focus is on observing whether the energy of high-frequency vibrations is concentrated in the key regions of the acoustic black hole structure to verify whether its energy focusing effect meets the design requirements.

[0071] System parameter experimental testing: Adjust the nonlinear adjustment parameters of the external branch circuit to ensure it can provide sufficient dynamic vibration absorption capacity in the low-frequency range, while maintaining good vibration response in the mid-to-high frequency range. Optimize the placement and coverage area of ​​the piezoelectric elements, and adjust their installation position based on experimental feedback to maximize vibration energy absorption.

[0072] After testing, it can be applied to real-world operating conditions to evaluate its overall 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 as controlled structure 1) was tested under simulated actual operating conditions. The vibration suppression effect of the system over a wide frequency range was recorded, including low-frequency vibration absorption capability and wide-frequency vibration control effect. Figure 5 This is a schematic diagram illustrating the low-frequency control effect of the controlled structure. Figure 6 This diagram illustrates the broadband control effect on the controlled structure. As can be seen, this invention enhances the dynamic vibration absorption effect in the low-frequency range by adding an external branch circuit, achieving excellent broadband vibration suppression. Furthermore, it allows for the examination of the system's long-term stability and reliability, and the evaluation of its durability under complex environments.

[0073] In summary, the method for regulating the vibration characteristics of an acoustic black hole structure provided in Example 1, through an external branch circuit connected to the piezoelectric-acoustic black hole composite structure, alters the structural characteristics of the acoustic black hole, enabling it to exhibit stronger dynamic vibration absorption capabilities in the low-frequency range. This method effectively regulates the low-frequency vibration characteristics of the acoustic black hole structure. Example 1 introduces a nonlinear mechanism to meet the demands of complex environments. By controlling the adjustable parameters of the external branch circuit, it can flexibly adapt to different vibration frequencies and operating conditions, improving its application range and efficiency. It possesses advantages of strong adaptability and flexibility, achieving efficient energy regulation and multi-band vibration control, wide-band vibration suppression, and efficient vibration reduction and noise reduction over a wide frequency range. Furthermore, Example 1, without increasing weight, combines the advantages of active and passive control, offering the benefits of lightweight structure and optimized functionality.

[0074] Example 2:

[0075] Example 2 provides a system for controlling 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 attached to the controlled structure, and the thickness of the acoustic black hole structure varies according to a power 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.

[0076] The system for regulating the vibration characteristics of an acoustic black hole structure provided in Example 2 is used to perform the method for regulating the vibration characteristics of an acoustic black hole structure as described in Example 1.

[0077] Since the characteristics or functions of each structure or circuit in the system provided in Embodiment 2 correspond to the limitations in the method provided in Embodiment 1, Embodiment 2 can be understood by referring to the description of Embodiment 1, and will not be repeated here.

[0078] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling the vibration characteristics of an acoustic black hole structure, wherein the acoustic black hole structure is attached to a controlled structure, and the thickness of the acoustic black hole structure varies 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 controlled by the external branch circuit, characterized in that... An external branch circuit is designed to be compatible with the piezoelectric element. By introducing nonlinear characteristics, the vibration mode characteristics of the piezoelectric-acoustic black hole composite structure are dynamically adjusted. This circuit can dynamically adjust the parameters of different components in the circuit according to the vibration response of the acoustic black hole structure.

2. The method of claim 1, wherein, The external branch circuit includes capacitors, resistors, and inductors connected in series or parallel.

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, inductance, and resistance values ​​in the external branch circuit, the vibration characteristics of the acoustic black hole structure can be dynamically adjusted, thereby achieving effective coupling between the vibration modal characteristics of the acoustic black hole structure and the controlled structure.

4. The method of claim 3, wherein the acoustic black hole structure is configured to have a frequency of 1 kHz or less. Setting the displacement response of an acoustic black hole structure The expression is: ; wherein, is a shape function of the displacement of the acoustic black hole structure; is a weight coefficient corresponding to the shape function, which is also a discretized generalized coordinate; Based on the principle of minimum potential energy, the Lagrange equations for the electromechanical coupling system comprising the piezoelectric-acoustic black hole composite structure and the external branch circuit are as follows: In the formula, M is the mass matrix of the piezoelectric-acoustic black hole composite structure, L is the inductance of the external branch circuit, R is the resistance of the external branch circuit, C is the capacitance of the external branch circuit, and K is the stiffness matrix of the piezoelectric-acoustic black hole composite structure. This is the imaginary part of the stiffness matrix. Let be the real part of the stiffness matrix. For external excitation frequency, As an external incentive, The first derivative of the discretized generalized coordinates, The second derivative of the discretized generalized coordinates; It is the charge; Let be the first derivative of the charge, and for Functions of R, i.e. , This represents the voltage across the piezoelectric element. The second derivative of the charge; The electromechanical coupling coefficient is... This is the transpose of the electromechanical coupling coefficient; For the capacitance of a piezoelectric element, 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 1, characterized in that, The strain information of the acoustic black hole structure is obtained, and the placement position of the piezoelectric element on the acoustic black hole structure is determined based on the strain information.

6. The method of claim 5, wherein the acoustic black hole structure is configured to have a resonant frequency of 1 kHz or less. Modal analysis is performed on the acoustic black hole structure to obtain modal analysis results containing the natural frequencies, mode shapes, and response characteristics of the acoustic black hole structure under multiple modes. Based on the modal analysis results of the acoustic black hole structure, strain information containing the strain distribution of the acoustic black hole structure under multiple modes is calculated.

7. The method of claim 1, wherein, Also includes: A damping element is placed on the acoustic black hole structure.

8. The method of claim 1, wherein, The acoustic black hole structure is an additional acoustic black hole structure, which is designed as a one-dimensional beam structure, a two-dimensional spiral structure, a two-dimensional rectangular structure, or a two-dimensional circular structure.

9. A system for implementing the method of controlling the vibrational characteristics of an acoustic black hole structure as described in any one of claims 1 to 3, comprising: Acoustic black hole structure and piezoelectric control unit; The acoustic black hole structure is attached to the controlled structure, and the thickness of the acoustic black hole structure varies according to a power 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 circuit is characterized in that it can dynamically adjust the parameters of different components in the circuit according to the vibration response of the acoustic black hole structure.

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