An active piezoelectric acoustic metamaterial with multi-physical effects and its control method

Abstract

The present invention relates to an active piezoelectric acoustic metamaterial with multiple physical effects and a control method. The metamaterial is used to reduce low-frequency vibrations of a substrate and includes multiple control units and a digital control module, each of which is electrically connected to the digital control module. The control unit includes an accelerometer and a piezoelectric plate. The accelerometer and piezoelectric plate are located on either side of the substrate, and both are attached to the substrate; or the piezoelectric plate is attached to the substrate, with the accelerometer attached to the side of the piezoelectric plate away from the substrate. The digital control module includes a digital controller, a first voltage amplifier circuit, and a second voltage amplifier circuit. The accelerometer is electrically connected to the digital controller via the first voltage amplifier circuit, and the piezoelectric plate is electrically connected to the digital controller via the second voltage amplifier circuit. This active piezoelectric acoustic metamaterial has a wide bandgap, and the control method has strong control effects and accurate range.

Description

Technical Field

[0001] The present invention relates to the field of vibration control technology, and in particular to an active piezoelectric acoustic metamaterial with multiple physical effects and a control method thereof. Background Art

[0002] Low-frequency vibration is a common problem in fields such as aerospace and marine engineering, negatively impacting the performance and service life of aircraft and shipbuilding equipment. Low-frequency vibrations have a long wavelength, requiring significant control, and are difficult to block due to their strong penetrating power. Therefore, traditional vibration control technologies struggle to effectively control low-frequency vibrations.

[0003] Piezoelectric acoustic metamaterials can achieve bandgap characteristics by generating localized resonance between piezoelectric elements and resonant shunt circuits, thereby hindering the propagation of elastic waves in the structure. Shunt circuits and digital impedance technologies essentially alter the dynamic stiffness and damping of composite structures, generating negative dynamic stiffness near the modal frequency to form a bandgap. Damping changes the width and depth of the bandgap, but the bandgap formed by negative dynamic stiffness is relatively small. When the modal frequency of the vibrating structure or the external vibration frequency changes significantly, exceeding the bandgap range, damping is often increased to broaden the effective vibration reduction frequency band. However, this reduces the bandgap depth and range, significantly diminishing the vibration reduction effect. Furthermore, existing shunt circuits and digital impedance technologies inevitably introduce additional equivalent resistance due to the large number of operational amplifier modules in the external circuit. These factors enhance the damping effect and limit the formation of low-frequency bandgaps. Summary of the Invention

[0004] Based on this, it is necessary to provide an active piezoelectric acoustic metamaterial and a control method with multiple physical effects, a wide low-frequency bandgap, strong control effect and accurate control range, in order to address the above technical problems.

[0005] In a first aspect, the present invention provides an active piezoelectric acoustic metamaterial with multiple physical effects for low-frequency vibration reduction of a substrate. The active piezoelectric acoustic metamaterial includes multiple control units and a digital control module for calculating a control signal according to a target frequency using a control law and sending the control signal to the multiple control units. Each control unit is electrically connected to the digital control module.

[0006] The control unit includes an accelerometer for converting a vibration acceleration signal into a voltage signal and a piezoelectric piece for receiving a control signal sent by a digital control module;

[0007] The accelerometer and the piezoelectric sheet are respectively arranged on both sides of the substrate, and the accelerometer and the piezoelectric sheet are both attached to the substrate; or the piezoelectric sheet is attached to the substrate, and the accelerometer is attached to the side of the piezoelectric sheet away from the substrate;

[0008] The digital control module includes a digital controller for calculating a control signal, a voltage amplifier circuit for amplifying a voltage signal output by an accelerometer, and a first voltage amplifier circuit for amplifying the control signal. The accelerometer is electrically connected to the digital controller through the voltage amplifier circuit, and the piezoelectric piece is electrically connected to the digital controller through the second voltage amplifier circuit.

[0009] In one embodiment, the control law is:

[0010]

[0011] Where K m (s) is the control law, v(s) is the control voltage output by the microcontroller, v a (s) is the control voltage input by the microcontroller unit, γ is the amplification factor, ω t is the target frequency, C p is the internal equivalent capacitance of the piezoelectric piece, R is the adjustable resistance of the active piezoelectric acoustic metamaterial damping that affects the multi-physics effect, and s is the Laplace operator.

[0012] In one embodiment, the digital controller includes a microcontroller unit and an analog-to-digital conversion unit and a digital-to-analog conversion unit connected to the microcontroller unit. The analog-to-digital conversion unit is connected between the first voltage amplifier circuit and the microcontroller unit, and the digital-to-analog conversion unit is connected between the second voltage amplifier circuit and the microcontroller unit.

[0013] In one embodiment, the substrate is a beam, a plate, or a shell.

[0014] In one embodiment, the base bodies of any two adjacent control units among the plurality of control units are integrally connected.

[0015] In a second aspect, the present invention further provides a control method for controlling the active piezoelectric acoustic metamaterial with the above-mentioned multi-physical effects to perform low-frequency vibration reduction, comprising:

[0016] Construct control laws;

[0017] Setting the parameters of the control model, specifically setting the size of the control law amplification factor γ and the size of the adjustable resistor R of the active piezoelectric acoustic metamaterial damping that affects the multi-physics effect;

[0018] The control law with parameters set is digitized and placed into the micro control unit;

[0019] The microcontrol unit calculates a control signal based on the digitized control law, and sends the control signal to the piezoelectric piece through the digital-to-analog conversion unit and the second voltage amplification circuit.

[0020] In one embodiment, the digitized control law is:

[0021]

[0022] Where a n is the coefficient of the feedback filter, b m is the coefficient of the feedforward filter, p represents the order of the feedforward filter, q represents the order of the feedback filter, k is the sampling time, x(k) is the voltage signal output by the analog-to-digital conversion unit at time k, and y(k) is the control signal output by the microcontroller unit.

[0023] In one embodiment, the microcontroller unit calculates the control signal based on the digitized control law, including:

[0024] The micro control unit receives the voltage signal output by the analog-to-digital conversion unit;

[0025] The microcontroller unit inputs the voltage signal output by the analog-to-digital conversion unit into a digitized control law, and the digitized control law calculates a control signal for controlling the active piezoelectric acoustic metamaterial with multi-physical effects to perform low-frequency vibration reduction.

[0026] The above-mentioned active piezoelectric acoustic metamaterial and control method with multiple physical effects, the active piezoelectric acoustic metamaterial is used to perform low-frequency vibration reduction on the substrate, including multiple control units and a digital control module for calculating the control signal through the control law according to the target frequency, each control unit is electrically connected to the digital control module; the control unit includes an accelerometer for converting the vibration acceleration signal into a voltage signal and a piezoelectric sheet for receiving the control signal sent by the digital control module, the accelerometer and the piezoelectric sheet are respectively arranged on both sides of the substrate, and the accelerometer and the piezoelectric sheet are both attached to the substrate; or the piezoelectric sheet is attached to the substrate, and the accelerometer is attached to the side of the piezoelectric sheet away from the substrate; the digital control module includes a digital controller for calculating the control signal, a voltage amplifier circuit for amplifying the voltage signal output by the accelerometer, and a voltage amplifier circuit for amplifying the control signal, the accelerometer is electrically connected to the digital controller through the voltage amplifier circuit, and the piezoelectric sheet is electrically connected to the digital controller through the voltage amplifier circuit. The accelerometer in each control unit collects the current vibration acceleration signal, converts the vibration acceleration signal into an electrical signal and sends it to the digital control module. The digital control module generates a control signal based on the electrical signal sent by the accelerometer and the target frequency and sends it to the piezoelectric piece. Under the control of the control signal, the active piezoelectric acoustic metamaterial combines with the matrix to produce a negative dynamic mass density band gap, a negative dynamic stiffness composite band gap and a damping effect, which can produce significant vibration attenuation at the target frequency and has a strong control effect. In addition, the control signal is generated based on the target frequency, so the control range of the active piezoelectric acoustic metamaterial is also more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1is a schematic diagram of a first specified position relationship among the accelerometer, the piezoelectric sheet, and the substrate in an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of a second specified position relationship among the accelerometer, the piezoelectric piece, and the substrate in an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of the structure of an active piezoelectric acoustic metamaterial with multi-physical effects installed on a substrate under a first specified position relationship in an embodiment of the present invention;

[0030] Figure 4 yes Figure 1 Structural diagram from another angle;

[0031] Figure 5 This is one of the flow charts of the active piezoelectric acoustic metamaterial control method for multi-physical effects in this embodiment;

[0032] Figure 6 1 is a schematic diagram of a specific structure of the connection between the active piezoelectric acoustic metamaterial with multiple physical effects and the substrate in an embodiment of the present invention;

[0033] Figure 7 Schematic diagram comparing the band gap generated by the active piezoelectric acoustic metamaterial of the present invention and the band gap generated by the bimorph piezoelectric acoustic metamaterial.

[0034] Explanation of the reference numerals: 100, substrate; 110, accelerometer; 120, piezoelectric sheet; 130, voltage amplifier circuit; 140, voltage amplifier circuit; 200, digital controller; 210, microcontroller unit; 220, analog-to-digital conversion unit; 230, digital-to-analog conversion unit. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] In one embodiment, Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, Figure 1 is a schematic diagram of a first specified position relationship among the accelerometer, the piezoelectric sheet, and the substrate in an embodiment of the present invention. Figure 2 is a schematic diagram of a second specified position relationship among the accelerometer, the piezoelectric sheet, and the substrate in an embodiment of the present invention, Figure 3 is a schematic structural diagram of an active piezoelectric acoustic metamaterial with multi-physical effects under a first specified position relationship in an embodiment of the present invention, Figure 4 yes Figure 1Schematic diagram of the structure from another angle. In this embodiment, the multi-physics active piezoelectric acoustic metamaterial, used to reduce low-frequency vibrations on a substrate 100, includes multiple control units and a digital control module for calculating control signals based on target frequencies using a control law. Each control unit is electrically connected to the digital control module. The control unit includes the substrate 100, an accelerometer 110 for converting vibration acceleration signals into voltage signals, and a piezoelectric plate 120 for receiving control signals from the digital control module.

[0037] Specifically, substrate 100 is a beam, plate, or shell of equipment such as a ship, spacecraft, or submarine. Preferably, substrate 100 is made of stainless steel. Using the active piezoelectric acoustic metamaterial of the present invention to reduce low-frequency vibrations on substrate 100 can improve the performance, service life, and concealment of equipment such as ships, spacecraft, or submarines.

[0038] Specifically, in the multi-physics-effect active piezoelectric acoustic metamaterial of this embodiment, the accelerometer can collect the vibration acceleration signal of the current structural vibration, convert the vibration acceleration signal into an electrical signal, and send it to the digital control module. The digital control module generates a control signal based on this electrical signal and the target frequency we need to control. This control signal is used to control the operation of the piezoelectric plate 120. The piezoelectric plate 120 can convert the electrical signal into mechanical vibration. The multi-physics-effect active piezoelectric acoustic metamaterial of this embodiment changes the damping, dynamic mass density, and dynamic stiffness of the composite structure through the negative feedback link in the control loop, generating a negative dynamic mass density and negative dynamic stiffness composite band gap, effectively isolating vibrations at the modal frequency. Using the digital control module to control vibration reduction has a good control effect. The digital control module generates a control signal based on the target frequency, which better matches the current low-frequency vibration. The control range of the active piezoelectric acoustic metamaterial of this embodiment is also more accurate.

[0039] In this embodiment, the substrate 100 and the piezoelectric sheet 120 are bonded together to form a substrate-piezoelectric structure, and the accelerometer 110 is bonded together to any side surface of the substrate-piezoelectric structure. The positional relationship among the accelerometer 110, the piezoelectric sheet 120 and the substrate 100 includes two designated positions.

[0040] Specifically, in the first designated position, the accelerometer 110 and the piezoelectric sheet 120 are respectively disposed on both sides of the substrate 100, and both the accelerometer 110 and the piezoelectric sheet 120 are attached to the substrate 100. In the second designated position, the piezoelectric sheet 120 is attached to the substrate 100, and the accelerometer 110 is attached to the side of the piezoelectric sheet 120 away from the substrate 100.

[0041] The digital control module includes a digital controller 200 for calculating control signals, a first voltage amplifier circuit 130 for amplifying the voltage signal output by the accelerometer 110, and a second voltage amplifier circuit 140 for amplifying the control signal. The accelerometer 110 is electrically connected to the digital controller 200 via the first voltage amplifier circuit 130, and the piezoelectric plate 120 is electrically connected to the digital controller 200 via the second voltage amplifier circuit 140. The voltage signal output by the accelerometer 110 is amplified to ensure that the output signal reaches the ADC acquisition voltage of the digital controller 200.

[0042] It should be noted that this embodiment specifically takes the active piezoelectric acoustic metamaterial with multi-physical effects including two control units as an example. All control units can be connected to one digital control module. For the sake of convenience, the accompanying drawings of this embodiment only show a schematic diagram of the connection relationship between one control unit and the digital control module.

[0043] Compared to bimorph piezoelectric metamaterials that only have a negative dynamic stiffness band gap, the active piezoelectric acoustic metamaterial in this embodiment produces a negative dynamic mass density and a negative dynamic stiffness composite band gap. Therefore, the active piezoelectric acoustic metamaterial in this embodiment has multi-physics effects and a wider band gap range.

[0044] In one embodiment, the control law is:

[0045]

[0046] Where K m (s) is the control law, v(s) is the control voltage output by the micro control unit 210, and v a (s) is the control voltage input by the microcontroller unit 210, γ is the amplification factor, ω t is the target frequency, C p is the internal equivalent capacitance of the piezoelectric piece 120 , R is the adjustable resistance of the active piezoelectric acoustic metamaterial damping that affects the multi-physical effect, and s is the Laplace operator.

[0047] Specifically, the control law can be derived based on the electromechanical coupling model of the active piezoelectric acoustic metamaterial.

[0048] In an optional embodiment, the digital controller 200 includes a microcontroller unit 210, and an analog-to-digital conversion unit 220 and a digital-to-analog conversion unit 230 connected to the microcontroller unit 210. The analog-to-digital conversion unit 220 is connected between the first voltage amplification circuit 130 and the microcontroller unit 210, and the digital-to-analog conversion unit 230 is connected between the second voltage amplification circuit 140 and the microcontroller unit 210. The digital controller 200 processes digital signals, while the accelerometer 110 and the piezoelectric film 120 process analog signals. Therefore, a digital-to-analog signal conversion unit is provided between the accelerometer 110 and the piezoelectric film 120 and the digital controller 200.

[0049] In one optional embodiment, the distance between any two adjacent control units in the plurality of control units is equal. In actual use, active piezoelectric acoustic metamaterials are used to achieve low-frequency vibration reduction in equipment or devices. Distributing the control units at the peaks and troughs of vibration can achieve better vibration reduction effects.

[0050] Preferably, the base bodies 100 of any two adjacent control units among the plurality of control units are integrally connected.

[0051] The band gap formed by negative dynamic mass density is wider. Many passive acoustic metamaterial designs in existing technologies have adopted this physical effect, but the method of applying the physical effect of negative dynamic mass density to the active regulation of metamaterials has not been disclosed in existing technologies.

[0052] Based on the same inventive concept, embodiments of the present invention also provide a method for controlling the aforementioned multiple physical effects of an active piezoelectric acoustic metamaterial for low-frequency vibration reduction, applying the physical effect of negative dynamic mass density to the active control of the metamaterial. The solution provided by this method is similar to the solution described in the aforementioned active piezoelectric acoustic metamaterial. Therefore, the specific limitations of one or more control method embodiments provided below can be found in the above-mentioned limitations on active piezoelectric acoustic metamaterials and will not be repeated here.

[0053] In one embodiment, Figure 5 As shown, Figure 5 FIG. 1 is a flow chart of a method for controlling active piezoelectric acoustic metamaterials with multiple physical effects in this embodiment. The control method in this embodiment includes:

[0054] S501: Constructing a control law. It can be understood that the control law is a function model.

[0055] S502: Setting parameters for the control model, specifically setting the size of the control law amplification factor γ and the size of the adjustable resistor R of the active piezoelectric acoustic metamaterial damping that affects the multi-physics effect.

[0056] Specifically, R can be set arbitrarily, generally between 0 and 2k. In this embodiment, it is set to 50. A larger R value increases the damping effect of the active piezoelectric acoustic metamaterial system across the entire frequency range, but this also reduces the range and depth of the band gap. In this embodiment, γ is set to 0.5. A larger γ value widens the band gap and enhances the vibration reduction effect. However, too large a γ value can cause system divergence.

[0057] S503: The control law with the parameters set is digitized and then placed into the micro control unit 210. Specifically, the control law is discretized according to the sampling time and converted into a differential equation.

[0058] S504 : The micro control unit 210 calculates a control signal based on the digitized control law, and sends the control signal to the piezoelectric piece 120 through the digital-to-analog conversion unit 230 and the second voltage amplifying circuit 140 .

[0059] The control method of this embodiment places the obtained digital control law into the microcontroller unit 210, and then inputs the electrical signal collected by the accelerometer 110 into the control unit. The microcontroller unit 210 uses the digital control law to calculate the control signal and sends it to the piezoelectric piece 120, so that the entire active piezoelectric acoustic metamaterial produces a damping effect, negative dynamic mass density and negative dynamic stiffness composite band gap, thereby achieving effective isolation of vibration at the modal frequency. This method has a good control effect.

[0060] In an optional embodiment, the digitized control law is:

[0061]

[0062] Where a n is the coefficient of the feedback filter, b m is the coefficient of the feedforward filter, p represents the order of the feedforward filter, q represents the order of the feedback filter, k is the sampling time, x(k) is the voltage signal output by the analog-to-digital conversion unit 220 at time k, and y(k) is the control signal output by the micro control unit 210.

[0063] Specifically, a n 、b m , p and q are all calculated through the discretization process.

[0064] In one embodiment, the micro control unit 210 calculates the control signal based on the digitized control law, including:

[0065] The micro control unit 210 receives the voltage signal output by the analog-to-digital conversion unit 220;

[0066] The microcontroller unit 210 inputs the voltage signal output by the analog-to-digital conversion unit 220 into the digitized control law, and the digitized control law calculates the control signal for controlling the active piezoelectric acoustic metamaterial with multi-physical effects to perform low-frequency vibration reduction.

[0067] In a specific embodiment, Figure 6 As shown, Figure 6 This is a schematic diagram of a specific structure of an active piezoelectric acoustic metamaterial with multiple physical effects in an embodiment of the present invention. In this embodiment, the composite beam structure substrate 100 is made of stainless steel, the accelerometer 110 is a MEMS accelerometer 110, the piezoelectric plate 120 is a piezoelectric ceramic PZT-5H, and the microcontroller is an STM32. The MEMS accelerometer 110 is the sensor, the piezoelectric ceramic PZT-5H is the actuator, and the accelerometer 110 circuit and the piezoelectric actuator (piezoelectric plate 120) are respectively attached to both sides of the substrate 100 structure, with a voltage amplifier circuit and a digital controller 200 connected between them. The active piezoelectric acoustic metamaterial has eight groups of control units. The eight groups of sensor-actuation control units composed of accelerometers 110 and piezoelectric plates 120 are evenly distributed on the substrate beam. This describes the active piezoelectric acoustic metamaterial with multiple physical effects and its control method.

[0068] Specifically, the accelerometer 110 uses the ADXL354 series capacitive MEMS accelerometer 110 from Analog Devices. To ensure that the output signal contains only acceleration due to structural vibration, only the z-axis acceleration signal is used, ensuring that the acceleration due to gravity is perpendicular to the z-axis. To ensure that the output signal reaches the AD acquisition voltage of the digital controller 200, the output voltage of the ADXL354 is amplified by κ times. The first voltage amplifier circuit 130 connected to the output of the digital controller 200 has an amplification factor of λ.

[0069] Specifically, the physical parameters of the base beam and the piezoelectric piece 120 in this embodiment are shown in Table 1 and Table 2, respectively.

[0070] Table 1 Physical parameters of base beam

[0071]

[0072] Table 2 Physical parameters of piezoelectric sheets

[0073]

[0074] Then, the control method of the present invention is used to control the active piezoelectric acoustic metamaterial with multiple physical effects.

[0075] In this embodiment, the control law of the active piezoelectric acoustic metamaterial is first derived based on the active piezoelectric acoustic metamaterial. According to the dynamic equation of the composite beam structure, the electromechanical coupling model of the active piezoelectric acoustic metamaterial is established. The electromechanical coupling equation is decoupled, and the r-th order modal response can be expressed as:

[0076]

[0077] Where H r (s) is the Laplace transform of the modal coordinates corresponding to the rth mode, Q r (s) is the Laplace transform of the modal excitation force of the composite structure, s is the Laplace operator, and β is the voltage amplification factor of the first voltage amplifier circuit 130; C p is the internal equivalent capacitance of the piezoelectric piece 120, Z = Ls + R (where L, C p With the target frequency ω t Satisfy ω 2t =1 / (LC p ), R is the adjustable resistor that affects the system damping), ζ r is the mechanical damping ratio corresponding to the rth mode of the composite structure, ω r is the rth order natural frequency of the composite structure, and α is a dimensionless parameter related to the electromechanical coupling effect.

[0078] Dynamic mass density m of the system e and dynamic stiffness s e It can be expressed as:

[0079]

[0080] Then, further deduction from Equations (3) and (4) yields the control law:

[0081]

[0082] Since the second voltage amplifier circuit 140 in the accelerometer 110 has a relatively large amplification factor, namely C f <<C p , the control law can be simplified to its general form:

[0083]

[0084] Specifically, the gain γ of the digital controller 200 represents a parameter for adjusting the bandgap performance, which is essentially an approximation of the electromechanical coupling coefficients α and β. Increasing the gain is equivalent to improving the electromechanical coupling capability. The control law of this embodiment does not depend on the model and only requires the input of the target frequency ω t The position, range and depth of the composite band gap can be controlled by adjusting the gain γ representing the electromechanical coupling ability and the resistance R representing the damping.

[0085] In this embodiment, only part of the above derivation process is given. Those skilled in the art are familiar with the calculation process of the remaining derivation process, which will not be described here in detail.

[0086] Preferably, in the present embodiment, after the internal digital controller 200 of STM32 system starts, initialization operation is first performed, interrupt instruction is turned on, and an infinite loop is entered to wait for A / D unit sampling signal, and an interrupt signal is sent to STM32 every time a sampling is completed, and an interrupt handler is entered to calculate the output pressure signal, and finally the control voltage is outputted outwardly by the D / A unit.

[0087] In addition, in order to verify that the width of the band gap generated by the active piezoelectric acoustic metamaterial of this embodiment is wider than that of the existing bimorph piezoelectric acoustic metamaterial, this embodiment uses the following method to calculate the band gap:

[0088] According to the electromechanical coupling model, under the condition that the dynamic mass density and dynamic stiffness of the composite structure are negative, the range of the composite band gap of negative dynamic mass density and negative dynamic stiffness is calculated:

[0089] The band gap ranges of negative dynamic mass density and negative dynamic stiffness are:

[0090]

[0091]

[0092] Formulas (6) and (7) show that when acceleration feedback is applied, two negative equivalent characteristics exist. In addition, as the resistance value increases, the electromechanical coupling capability of the system weakens, and the band gap range gradually decreases; conversely, as the resistance value decreases, the electromechanical coupling capability of the system increases, and the band gap range gradually expands.

[0093] If R is ignored and Z = Ls, the maximum range of the band gap can be obtained:

[0094]

[0095] The values ​​of α and β represent the electromechanical coupling capability of the piezoelectric element 120. Larger values ​​indicate stronger interaction between the piezoelectric element and the substrate 100, leading to a wider bandgap range. Increasing the number of control units also enhances the electromechanical coupling capability to a certain extent, further expanding the bandgap range. Because the negative equivalent mass density bandgap and the negative equivalent stiffness bandgap lie above and below the target frequency ωt, respectively, the composite bandgap is located just around the target frequency. As the target frequency increases, the bandgap range also increases accordingly.

[0096] In this embodiment, the experiment uses a signal generator to output an excitation signal to induce the vibration of the beam structure, and uses the accelerometer 110 to measure the excitation point and end of the beam structure. The modal frequency of 107.3 Hz is selected as the target frequency for vibration control, and Labview is used for data acquisition. Finally, MATLAB is used for data processing. Figure 7 As shown, Figure 7 Schematic diagram comparing the band gap generated by the active piezoelectric acoustic metamaterial of the present invention and the band gap generated by the bimorph piezoelectric acoustic metamaterial. Figure 7 As can be seen, the active piezoelectric acoustic metamaterial of the present invention achieves a wide bandgap and approximately 70dB of vibration attenuation, generated by the combined effects of negative dynamic mass density and negative dynamic stiffness. In comparison, the bandgap produced by bimorph piezoelectric acoustic metamaterials is below 107.3Hz, requiring frequency compensation, and has only a narrow negative dynamic stiffness bandgap. The active piezoelectric acoustic metamaterial of the present invention produces a wider bandgap.

[0097] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0098] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An active piezoelectric acoustic metamaterial with multiple physical effects, characterized in that: Used for performing low-frequency vibration reduction on a substrate (100), the active piezoelectric acoustic metamaterial comprises a plurality of control units and a digital control module for calculating a control signal according to a target frequency through a control law and sending the control signal to the plurality of control units, each of the control units being electrically connected to the digital control module; The control unit comprises an accelerometer (110) for converting a vibration acceleration signal into a voltage signal and a piezoelectric piece (120) for receiving a control signal sent by a digital control module; The accelerometer (110) and the piezoelectric sheet (120) are respectively arranged on both sides of the substrate (100), and the accelerometer (110) and the piezoelectric sheet (120) are both attached and connected to the substrate (100); or the piezoelectric sheet (120) is attached and connected to the substrate (100), and the accelerometer (110) is attached and connected to a side of the piezoelectric sheet (120) away from the substrate (100); The digital control module comprises a digital controller (200) for calculating a control signal, a first voltage amplifying circuit (130) for amplifying a voltage signal output by an accelerometer (110), and a second voltage amplifying circuit (140) for amplifying the control signal, wherein the accelerometer (110) is electrically connected to the digital controller (200) via the first voltage amplifying circuit (130), and the piezoelectric piece (120) is electrically connected to the digital controller (200) via the second voltage amplifying circuit (140); The digital controller (200) comprises a micro control unit (210), an analog-to-digital conversion unit (220) and a digital-to-analog conversion unit (230) connected to the micro control unit (210); The control law is: （1） Where, K m (s ) is the control law, v ( s ) is the control voltage output by the microcontroller unit, v a ( s ) is the control voltage input by the microcontroller unit, γ is the magnification, ω t is the target frequency, C p is the internal equivalent capacitance of the piezoelectric piece, R is the tunable resistance of the active piezoelectric acoustic metamaterial damping that affects multi-physics effects, s is the Laplace operator.

2. The active piezoelectric acoustic metamaterial with multiple physical effects according to claim 1, characterized in that: The analog-to-digital conversion unit (220) is connected between the first voltage amplifying circuit (130) and the micro control unit (210), and the digital-to-analog conversion unit (230) is connected between the second voltage amplifying circuit (140) and the micro control unit (210).

3. The active piezoelectric acoustic metamaterial with multiple physical effects according to claim 2, characterized in that: The base (100) is a beam, a plate or a shell.

4. The active piezoelectric acoustic metamaterial with multiple physical effects according to claim 3, characterized in that: The base bodies (100) of any two adjacent control units among the plurality of control units are integrally connected.

5. A control method for controlling the active piezoelectric acoustic metamaterial with multi-physical effects according to any one of claims 1 to 4 to perform low-frequency vibration reduction on a substrate, characterized in that: include: Construct control laws; Set the parameters of the control law, specifically set the control law amplification factor γ The magnitude and influence of multi-physics effects on the tunable resistance of active piezoelectric acoustic metamaterial damping R size; The control law with parameters set is digitized and placed into the micro control unit; The micro control unit calculates a control signal based on the digitized control law, and sends the control signal to the piezoelectric piece through the digital-to-analog conversion unit and the second voltage amplification circuit.

6. The control method according to claim 5, characterized in that: The digitized control law is: （2） Where, a n are the coefficients of the feedback filter, b m are the coefficients of the feedforward filter, p represents the order of the feedforward filter, q represents the order of the feedback filter, k is the sampling time, x ( k )for k The voltage signal output by the analog-to-digital conversion unit at this moment, y ( k ) is the control signal output by the microcontroller unit.

7. The control method according to claim 6, characterized in that: The microcontroller unit calculates the control signal based on the digitized control law, including: The micro control unit receives the voltage signal output by the analog-to-digital conversion unit; The microcontrol unit inputs the voltage signal output by the analog-to-digital conversion unit into a digitized control law, and the digitized control law calculates a control signal for controlling the active piezoelectric acoustic metamaterial with multi-physical effects to perform low-frequency vibration reduction.

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