Sound energy collecting device by coupling nonlinear Helmholtz resonator and stretching structure

Abstract

The invention relates to the technical field of sound energy collection, in particular to a sound energy collection device by coupling a nonlinear Helmholtz resonator and a stretching structure. According to the device, input sound pressure is amplified through the Helmholtz resonator, and the energy collection efficiency is improved by integrating the piezoelectric beam and the stretching structure. External noise is introduced into the noise input module of the acoustic barrier. The module is a cuboid, and a circular truncated cone cavity is dug in the cuboid. And then the incident sound wave enters the Helmholtz resonator, and the device amplifies the sound pressure through the acoustic resonance principle. The amplified sound pressure drives a piezoelectric beam with a stretching structure in the base structure to vibrate, and then kinetic energy is converted into electric energy through a direct piezoelectric effect (mechanical energy to electric energy). And then the electric energy is stored in a capacitor forming an energy storage module, so that power generation is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sound energy collection, in particular to a sound energy collection device by coupling a nonlinear Helmholtz resonator and a tensile structure. BACKGROUND

[0002] The energy distributed in the natural environment, such as solar energy, wind energy, mechanical energy, thermal energy and sound energy, has significant recycling value because these energy forms are ubiquitous in human daily life. The sound energy distributed in the environment has extremely low density, which leads humans to regard it as noise rather than a sustainable energy that can be recycled and utilized. To effectively recycle and utilize sound energy, its density must be improved, which is the core technical challenge faced by current research. Three main methods to improve the density of sound energy include: using Helmholtz resonators, Fabry-Perot resonators and phononic crystals to achieve sound energy focusing and amplification. These acoustic devices can convert sound energy into electrical energy through piezoelectric, electromagnetic and triboelectric means. Research on combining Helmholtz resonators with piezoelectric devices (such as cantilever structures) has been widely carried out. In the field of acoustic energy harvesting (AEH), low-frequency sound waves as a more abundant environmental resource, their energy conversion efficiency depends on the resonance frequency and resonance gain effect of the resonator (HR). However, it is difficult to achieve satisfactory sound energy recycling efficiency and meet the operation requirements of most small devices by relying solely on these methods. SUMMARY

[0003] The present application aims to solve the problems in the background art and provides a sound energy collection device by coupling a nonlinear Helmholtz resonator and a tensile structure, which aims to improve the density of sound energy and improve its energy output and effective working bandwidth for powering small wireless sensing devices.

[0004] The technical solution of the present application, the first aspect of the present application provides a sound energy collection device by coupling a nonlinear Helmholtz resonator and a tensile structure, which includes: an acoustic absorption barrier; The acoustic absorption barrier is composed of a plurality of unit structures, each of which operates independently; The acoustic absorption barrier specifically includes: A noise input module for absorbing noise excitation from the outside world and sending incident sound waves into the sound pressure amplification module; A sound pressure amplification module for amplifying sound pressure based on acoustic resonance principles after receiving the incident sound waves; A piezoelectric sensing module installed at the output end of the sound pressure amplification module, which receives the sound wave excitation generated by the sound pressure amplification module and produces vibration, generates electrical energy and improves the output voltage and electrical power; An energy storage module connected to the output end of the piezoelectric sensing module, which stores the electrical energy generated by the piezoelectric sensing module.

[0005] Preferably, the noise input module is a cuboid structure with a circular truncated cone cavity. The height is 5 cm, the width is 25 cm, and the radii of the upper and lower bases of the circular truncated cone cavity are 12 cm and 2.6 cm, respectively.

[0006] Preferably, the sound pressure amplification module is a Helmholtz resonator installed at the output end of the noise input module. The neck of the Helmholtz resonator is a hollow cylinder with a central cavity. The hollow cylinder with a central cavity in the Helmholtz resonator is installed in position with the circular truncated cone cavity of the noise input module. The thickness of the side wall of the hollow cylinder is 0.6 cm, the height is 3 cm, and the inner radius is 2 cm. The height of the cavity in the Helmholtz resonator is 6 cm, the thickness of the side wall is 1.5 cm, and the side length of the bottom plate is 17 cm.

[0007] Preferably, the piezoelectric sensing module includes a piezoelectric beam, a piezoelectric sheet, and a stretching structure. The one end of the piezoelectric beam is a vertically arranged support column. The piezoelectric beam extends to one side from the middle position of the support column and is arranged vertically with the support column. The stretching structure is fixed to one end of the piezoelectric beam close to the support column. The piezoelectric sheet is PZT-5H with a thickness of 0.3 cm. The piezoelectric sheet is attached above the stretching structure, and the width of the piezoelectric sheet is consistent with the width of the beam. The length of the piezoelectric beam is 7.3 cm, the width is 1.6 cm, and the thickness is 0.2 cm.

[0008] Preferably, the area of the stretching structure is 2.4 cm*1.6 cm, and the stretching structure is designed as a hexagonal negative Poisson's ratio superstructure.

[0009] Preferably, the sound pressure amplification ratio and the resonance frequency of the Helmholtz resonator depend on the geometric parameters of the neck and the cavity inside the Helmholtz resonator. By designing the geometric parameters, the Helmholtz resonator produces sound pressure gain in the required frequency range.

[0010] Preferably, under the long-wave limit, the motion of air particles in the neck of the Helmholtz resonator exhibits a nonlinear motion state (nonlinear elastic restoring force is generated in the cavity). This motion state includes single-period, multiple-period bifurcation, quasi-periodic, and chaotic motion states.

[0011] Preferably, the piezoelectric beam itself has multiple vibration modes and resonance frequencies. By reasonably designing the piezoelectric beam, the vibration mode and resonance frequency of the piezoelectric beam are adjusted to match the optimal resonance mode of the piezoelectric beam with the acoustic resonance of the Helmholtz resonator, achieving double gain of the piezoelectric beam vibration.

[0012] Preferably, the stretching structure causes the longitudinal and transverse stresses of the piezoelectric beam to produce a superposition effect instead of cancellation when the piezoelectric beam is excited, resulting in greater stress distribution and improving the gain of the electric energy output.

[0013] The second aspect of the present application provides an acoustic absorption assembly, comprising a plurality of the above-mentioned sound energy collection devices; the sound energy collection devices are arranged in a noisy environment of a dance hall, a bar or a highway, absorb noise and convert it into electrical energy to power a miniaturized wireless sensing device.

[0014] Compared with the prior art, the present application has the following beneficial technical effects: 1. The Helmholtz resonator can improve the density of sound energy and enhance the sound pressure inside the cavity. The noise input module can facilitate the entry of noise excitation into the Helmholtz resonator, producing a certain acoustic compliance; 2. The matching of acoustic resonance and the optimal vibration mode of the piezoelectric beam makes the piezoelectric beam produce greater vertical displacement; 3. The tensile structure, i.e. the negative Poisson's ratio superstructure, can increase the stress distribution of the piezoelectric sheet at the fixed end of the piezoelectric beam, so that the piezoelectric sheet can produce higher induced voltage and electric power. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The structure and working principle of the acoustic absorption barrier.

[0016] Figure 2 The model diagram of the piezoelectric beam in the embodiment of the present application; wherein (a-c) are the equivalent spring-mass oscillator conversion model diagrams of the piezoelectric beam and the Helmholtz resonator; (d) is a diagram showing the change of the system potential energy function curve with the parameter β; (e) is a static bifurcation diagram of the undisturbed system (the bifurcation point where the multiple solutions turn into a single solution is shown by a dotted line); (f) is a phase trajectory curve of the undisturbed system.

[0017] Figure 3 The experimental result diagram of the HR system in the embodiment of the present application; wherein, (a) is the maximum Lyapunov index distribution diagram (with excitation amplitude and excitation frequency as coordinates) and the bifurcation diagram (with excitation frequency as coordinates) of the HR system when the parameter β value is 0.2, 0.4 and 1.36; (b) is the bifurcation diagram of the HR system under the change of the amplitude parameter F at two excitation frequencies ω=0.5 and ω=1.0; (c) is the spatial distribution diagram of the phase trajectory (purple) and the Poincare map (red) of the HR system in the chaotic state, and the third dimension is the potential energy distribution.

[0018] Figure 4 The dynamic diagram of the piezoelectric beam under the excitation of sound waves in the embodiment of the present application; wherein, (a) is a three-dimensional dynamic diagram of the piezoelectric beam under the excitation of sound waves; (b) is a diagram of the piezoelectric beam and the tensile structure assembly; (c) is a stress distribution image of the piezoelectric beam in the resonant state before and after the introduction of the tensile structure. In order to enhance the contrast, the color and the upper limit of the stress have been limited.

[0019] Figure 5 Figure 1 shows a simulation model of the acoustic absorption barrier unit structure in an embodiment of the present invention; (a) is the simulation model of the acoustic absorption barrier unit structure; (b) shows the characteristic frequency and vibration mode of the piezoelectric beam; (c) shows the displacement and stress distribution cloud diagrams of the two piezoelectric beams under the parameter conditions that produce the highest output voltage. I-III are piezoelectric beams with tensile structures, and IV-VI are conventional piezoelectric beams; (d) shows the sound pressure amplitude distribution inside the Helmholtz resonator.

[0020] Figure 6 This section provides a block diagram of the experimental setup and an introduction to the experimental model and equipment.

[0021] Figure 7 For parameters and The impact on AEHD energy harvesting performance. A schematic diagram shows a comparison between experimental and simulation results.

[0022] Figure 8 This section compares experimental and simulation results for the voltage and power of the energy harvesting device. It includes the amplitude-frequency response curves of the voltage and power of the energy harvesting device, as well as the effect of changes in external circuit resistance on the voltage and power amplitudes.

[0023] Figure 9 The impact of incident sound pressure on the energy harvesting performance of the AEHD includes output voltage and output power. Detailed Implementation

[0024] Example 1 Figure 1 A 3D model and schematic diagram of an AEHD are shown. An AEHD is an acoustic absorption barrier composed of multiple unit structures. The device includes four modules: a noise input module, a sound pressure amplification module, an energy-to-electricity conversion module, and an energy storage module. Noise from venues such as nightclubs, bars, and highways is introduced into the lower structure of the barrier, namely the noise input module. This module is a cuboid with a height of H1 and a side length of L1. A frustum-shaped cavity is carved out of the cuboid. The radius of the surface in contact with the outside is R1, and the radius of the other side is the sum of the radius of the HR neck and the thickness of the neck wall. The incident sound wave first enters the HR module—this module amplifies the sound pressure through the principle of acoustic resonance. The amplified sound pressure drives the piezoelectric beam within the base structure to vibrate, and then converts the kinetic energy into electrical energy through the direct piezoelectric effect (mechanical energy to electrical energy). The electrical energy is then stored in the capacitors that constitute the energy storage module, thereby realizing power generation. This study selects a single unit to characterize the system performance under specific constraints. Figure 2 As shown in (a) and 2(b), for ease of analysis, the vibrating piezoelectric beam can be conceptually simplified into a linear spring-mass-damping model; Area of ​​the HR cylindrical neck and the volume of the cavity The resonance frequency of the HR cavity can be calculated by the following equation:

[0025] where is the radius of the neck, is the height of the HR cavity, is the side length of the square.

[0026] The sound pressure amplification factor of the HR under resonance condition and the resonance frequency can be expressed as:

[0027] where is the speed of sound in air, is the length of the neck, is the correction factor, is the sound pressure in the cavity, is the input sound pressure.

[0028] The HR cavity controls the resonance frequency of the system by amplifying the sound pressure in the cavity. The cavity volume and the neck geometry together determine the frequency and the condition of sound energy amplification. When modeling the system in the long-wave limit, the air in the cavity is approximated as a nonlinear spring (k) and a dashpot (c) (c). Thus, the pressure change induced by the neck air displacement Figure 2 can be expressed as:

[0029] where is the specific heat ratio of air, is the density of air.

[0030] The specific heat ratio of the neck air of the resonator depends on the acoustic excitation frequency and the molecular properties of air. Its thermodynamic behavior transitions between two modes: at high driving frequencies, the significant temperature gradient makes the process adiabatic; while at low frequencies, it approaches isothermal conditions. In addition, the space occupied by the internal piezoelectric material and the pillars needs to be considered when calculating the cavity volume. The dynamic equation of the air in the neck region can be expressed as:

[0031] where is the sum of the acoustic impedance and the friction impedance at the HR inlet, is the pressure change near atmospheric pressure.

[0032] ​​The neck air generates a friction force, which forms a damping effect (nonlinear characteristics of the damping are neglected here), while the relative change in cavity pressure due to the displacement of the neck air generates a nonlinear elastic restoring force. To investigate the nonlinear behavior of the system, we assume that the acoustic excitation is in the form of a harmonic signal. The aim of this study is to optimize the performance of the HR. The method is based on the long-wave approximation, i.e. the wavelength of the incident sound wave is much larger than the physical dimensions of the resonator. Therefore, the pressure field can be modeled as a uniform phase distribution within the resonator volume. Equation (6) is normalized as follows:

[0033] where , , , , , .

[0034] The potential energy function of the system is given by:

[0035] From equations (7) and (8), it can be seen that the values of the parameters and depend on the specific heat ratio of air. The specific heat ratio accurately describes the thermodynamic state of the air molecules in the neck and cavity. At lower excitation frequencies, the cavity temperature can be maintained at a constant temperature. Therefore, an intermediate value can be used, which adequately describes the thermodynamic state of the air molecules in the throat and cavity. According to existing experimental results, the estimated values of the parameters are and . In subsequent calculations of the potential energy, the values of the parameters and can be referred to the experimentally determined values. The potential energy function curve of the HR system is shown in Figure 2 (d). As the parameter increases, the system transitions from an asymmetric bistable system to a monostable system (including a quasi-zero stiffness state with a flat potential well). Figure 2 (e) depicts the static bifurcation phenomenon induced by the parameter β. According to the analytical prediction in Figure 2 (e), the curve bifurcates at , changing from three solutions to a single solution. This indicates a transition from a bistable to a monostable system, consistent with the analysis results in Figure 2 (d).

[0036] Numerical tests based on the mathematical model describing the HR system reveal the effects of the excitation frequency and the excitation amplitude on the distribution of chaotic motion regions. Although there are various evaluation methods, the largest Lyapunov exponent is the most commonly used and bifurcation diagrams. The multicolor distribution map can be used to assess the nonlinear state of the HR system. Moreover, the effectiveness of the largest Lyapunov exponent can be verified by comparison with the bifurcation diagram.

[0037] All multicolor maps are based on initial conditions , drawn distribution generation. When takes positive values, the system exhibits chaotic behavior; otherwise, the phase trajectory tends to a stable point or a periodic orbit. On the other hand, when approaches zero, the system involves a bifurcation point. From a technical point of view, the choice of the parameter significantly affects the nonlinear characteristics of the HR system. Figure 3 (a) demonstrates typical results, revealing the influence of the parameter on the distribution of the largest Lyapunov exponent. Figure 3 The bifurcation diagram corresponding to the largest Lyapunov exponent in (a) is plotted with the excitation frequency as the horizontal coordinate. The system exhibits a characteristic alternating between periodic and chaotic behavior, with the largest Lyapunov exponent corresponding to the bifurcation Figure 1 . Figure 3 (b) demonstrates bifurcation diagrams at two excitation frequencies (0.5 and 1.0), where the excitation amplitude serves as the varying parameter. For the system with quasi-zero stiffness characteristics ( ), it is more susceptible to entering a chaotic state at lower external excitation amplitudes and frequencies compared to the other two cases ( and ). Figure 3 (c) demonstrates the phase trajectory curve and Poincare map when the HR system is in a chaotic state under selected parameters. The trajectory distribution is represented by the purple curve, while the Poincare map is presented through the red scatter plot. The third dimension corresponds to the potential energy of the HR system. The parameters are chosen based on the distribution map of the largest Lyapunov exponent of the HR system ( Figure 3 (a)).

[0038] When the piezoelectric beam is mounted at the bottom of the AEHD, its vibration is caused by the acoustic pressure difference between the upper and lower surfaces of the piezoelectric beam, as shown in Figure 2 (b). Its expression is as follows:

[0039] where is the acoustic pressure amplitude, is the distance from the HR neck to the piezoelectric beam, is the thickness of the piezoelectric beam. From equation (9), it can be seen that the acoustic pressure difference is determined by the parameters and A joint decision was made. Given the extremely thin nature of the piezoelectric beam, the parameters were adjusted. This is the most practical solution. A support column is installed at the bottom of the cavity, and the piezoelectric beam is bonded to the support column using high-strength adhesive. The parameters can be adjusted by changing the distance between the piezoelectric beam and the bottom of the cavity (i.e., the height of the support column). The value of .

[0040] like Figure 4 As shown in (a), the device employs a piezoelectric beam structure. To fully utilize the high strain concentration effect resulting from the negative Poisson's ratio, the fixed end of the aluminum substrate is designed as a hexagonal negative Poisson's ratio structure, fabricated using a laser cutting process. A PZT-5H piezoelectric sheet is bonded to this structure using a strong adhesive, resulting in a stress distribution (…). Figure 4 (b) This directly endows the device with excellent energy conversion capabilities.

[0041] The core advantage of tension structures lies in their distinctly different deformation mechanisms. For example... Figure 4 As shown in (b), when subjected to longitudinal force, this structure exhibits lateral contraction due to its negative Poisson's ratio characteristic, a stark contrast to the expansion behavior of traditional materials. This results in longitudinal stress ( ) and transverse stress ( The stress state is in the same direction. When this stress state is transmitted to the piezoelectric element, it causes the average stress in both directions to maintain the same sign. Because the output power is related to the average stress ( and This coordinated stress field is directly proportional to the energy generation efficiency, significantly enhancing the energy generation efficiency.

[0042] The key significance of formula (10) lies in the fact that the output power directly depends on the algebraic sign of the average stress components. The tensile structure generates average stresses of the same sign in both principal stress directions, leading to the superposition rather than cancellation of stress effects. This mechanism results in a higher output power for the piezoelectric beam than that of a conventional piezoelectric beam. Furthermore, this effect can be further enhanced by deliberately designing the tensile structure to achieve a high stress distribution.

[0043] Table 1 Model parameters used for experimental testing and numerical simulation

[0044] The energy harvesting efficiency of a piezoelectric beam with a tensile structure was studied using the finite element method. A finite element model was established in COMSOL Multiphysics software, and its geometric and physical parameters are shown in Table 1.

[0045] To facilitate comparison between a general piezoelectric beam and a piezoelectric beam with a tensile structure, the upper stress limit is set to 8 × 10⁻⁶. 4N / m³. Both beams were subjected to external acoustic excitation with an amplitude of 1 Pa. As Figure 4 (c) shows that the stress distribution of the beam plate is uniform in the connecting end region. In contrast, the tensile structure concentrates stress and strain in the more flexible tensile regions, especially in the outwardly curved corner regions.

[0046] As Figure 5 (a) shows, to simulate the collection of acoustic energy during acoustic wave propagation, the piezoelectric beam is installed at the bottom of the AEHD tube to improve the energy collection efficiency through acoustic resonance. The sound pressure level of the incident sound in the simulation is 94 dB.

[0047] Figure 5 The simulation results shown in (a) show that the sound pressure amplification coefficient in the resonant cavity is 24.4 at a frequency of 309 Hz. It should be noted that in this sound pressure simulation, the HR bottom is not integrated with a piezoelectric element, and only the sound pressure amplification coefficient inside the cavity is measured. The space occupied by the piezoelectric element (including the support) will affect the acoustic resonance frequency of the HR. Subsequently, the characteristic frequency of the piezoelectric beam was tested to ensure that its vibration mode could match the acoustic resonance of the HR (b), thereby further improving the energy collection efficiency. The first and second vibration modes of the piezoelectric beam represent ideal vibration modes, so we expect the acoustic resonance frequency to fall within these frequency bands. Figure 5

[0048] A custom measurement device was used for experimental characterization to verify the established model. The complete experimental setup is shown in Figure 6 , where Figure 6 (a-c) respectively show the model and its details. A specific frequency of acoustic excitation was provided by a loudspeaker to verify the method. In the energy conversion module, an aluminum piezoelectric beam with a tensile structure was fixed to the support at the bottom of the HR. The piezoelectric element was bonded to the patterned region of the tensile structure. When the HR amplifies the sound pressure, the beam body vibrates, generating a potential difference between its metal electrodes.

[0049] The experiment was conducted in the laboratory of the Mechanical Engineering Building of Southeast University. The specific arrangement of the experimental equipment is shown in Figure 6 (c). Due to the limitations of experimental conditions, a single structural unit was used to simulate the behavior of the entire acoustic absorption barrier. The prepared unit structure contains a piezoelectric beam with its base fixed to the base. The beam is perpendicular to the direction of the incident sound wave. The bottom plate is assembled with the main body by high-strength adhesive. The excitation mode, frequency, and sound pressure level of the sound field are precisely adjusted by a computer control system: the computer-controlled signal transmitter sends instructions to the power amplifier, which in turn drives the loudspeaker to work. The voltage output signal of the piezoelectric beam is displayed by an oscilloscope and recorded in the computer.

[0050] ​The piezoelectric beam is mounted on the support pillars at the bottom of the AEHD to receive acoustic waves. The deformation of the piezoelectric film caused by the acoustic pressure generates electrical energy. An optimized 20 kΩ resistor is used to obtain the output voltage, and the incident sound pressure level is 94 dB. The test results include a comparative analysis of numerical simulation and experimental simulation. Figure 7 The induced voltage amplitude-frequency response curves of the piezoelectric beam with a tensile structure and the general piezoelectric beam are shown. This study investigates the effects of support pillar height and beam length . The parameters determine the stiffness and resonance frequency of the beam, and by adjusting , the acoustic resonance matching of the beam body and the cavity can be achieved.

[0051] As can be seen from equation (9) and the description above, the excitation amplitude applied to the beam depends on the pressure difference between its upper and lower surfaces . By changing the support pillar height, the parameter can be adjusted. For the general piezoelectric beam, the energy harvesting efficiency reaches a maximum value when the beam length is 0.09 meters, and the peak output voltage is 0.36 V. For the piezoelectric beam with a tensile structure, the energy harvesting efficiency reaches a maximum value when the beam length is 0.073 m, and the peak output voltage is 0.55 V. Compared to the general piezoelectric beam, the maximum output voltage of the tensile structure beam is increased by 53%. In experimental tests, the maximum voltages of the two structures are 0.33 V and 0.51 V, respectively, with an increase rate of about 50%. The frequency deviation corresponding to the resonance remains within 10 Hz, indicating that the experimental results have a high degree of consistency with the simulation results. The introduction of the tensile structure changes the resonance frequency of the piezoelectric beam, resulting in a change in the required beam length for optimal acoustic resonance matching with the cavity. As shown in Figure 7 (a) and Figure 7 (b), the support pillar height has a significant impact on the output voltage of the piezoelectric beam. As the support pillar height decreases, the voltage amplitude shows a downward trend. Changes in the support pillar height have a small effect on the cavity volume, so the frequency corresponding to the maximum output voltage does not change significantly. Figure 7 (c) and Figure 7 (d) show that changes in the beam length change its resonance frequency. At this time, the acoustic resonance cannot match the resonance mode of the beam, resulting in a significant decrease in the maximum output voltage.

[0052] To determine the optimal excitation frequency within the 240-280 Hz frequency band, which can achieve the best matching of the HR acoustic resonance and the beam structure resonance, the output voltage under a constant 100 dB sound pressure level is analyzed, eliminating the effects of sound pressure fluctuations. Figure 8(a) Subsequently, the amplitude-frequency response curves of the conventional piezoelectric beam and the beam with tensile structure (AS) under the sweep excitation were compared. The maximum output voltage of 1.03V was recorded at about 248Hz. In addition, the output power reached 53.2μW at this frequency Figure 8 (c) which was highly consistent with the numerical simulation of the energy harvesting performance.

[0053] By systematically scanning the load resistance from 5kΩ to 40kΩ, the optimal power output of the AEHD was determined. Figure 8 (b) and Figure 8 (d) respectively plotted the curves of the output voltage and power under the open-circuit resonant frequency with the change of the external resistance. The output voltage was recorded in the form of amplitude. The electric power was calculated according to Ohm's law (power = (voltage)² / resistance). With the increase of the external resistance, the voltage amplitude showed a monotonic increasing trend, and finally reached about 1.33V. Under the optimal external resistance of 25kΩ, the maximum output power of 56.64μW was achieved.

[0054] In addition, a study was conducted to evaluate the influence of the sound pressure amplitude (1-5 Pa) on the AEHD under the open-circuit resonant condition Figure 9 ). The results showed that the amplitudes of the voltage and the output power increased with the increase of the sound pressure, showing a nearly linear positive correlation. At the sound pressure of 5 Pa, the amplitudes of 2.95V and 0.435mW were measured, respectively.

[0055] Embodiment 2 This embodiment provides an acoustic absorption assembly comprising a plurality of the sound energy harvesting devices in embodiment 1; the sound energy harvesting devices are arranged in the noise environment of a dance hall, a bar or a highway, absorb noise and convert it into electric energy, which is then stored in the capacitor constituting the energy storage module to power the miniaturized wireless sensing device. The device amplifies the input sound pressure through the Helmholtz resonator and improves the energy harvesting efficiency through the integrated piezoelectric beam and tensile structure.

[0056] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited thereto, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the present application.

Claims

1. A sound energy harvesting device that couples a nonlinear Helmholtz resonator to a tensile structure, characterized in that, include: Acoustic absorption barrier; The acoustic absorption barrier is composed of multiple unit structures, each of which operates independently; The acoustic absorption barrier specifically includes: Noise input module: used to absorb noise excitation from the outside and send the incident sound wave to the sound pressure amplification module; Sound pressure amplification module: It is used to receive incoming incident sound waves and amplify the sound pressure based on the principle of acoustic resonance; Piezoelectric sensing module: Installed at the output end of the sound pressure amplification module, it receives the sound wave excitation generated by the sound pressure amplification module and generates vibration, producing electrical energy and increasing the output voltage and power; Energy storage module: Connected to the output of the piezoelectric sensing module, it stores the electrical energy generated by the piezoelectric sensing module.

2. The acoustic energy harvesting device by coupling a nonlinear Helmholtz resonator with a tensile structure according to claim 1, characterized in that, The noise input module is a cuboid structure with a frustum-shaped cavity carved into its body.

3. The acoustic energy harvesting device according to claim 1, which couples a nonlinear Helmholtz resonator to a tensile structure, is characterized in that... The sound pressure amplification module is a Helmholtz resonator, which is installed at the output of the noise input module; The Helmholtz resonator has a hollowed-out cylinder at its neck; the hollowed-out cylinder in the neck of the Helmholtz resonator is aligned and installed with the frustum cavity of the noise input module.

4. The acoustic energy harvesting device according to claim 1, which couples a nonlinear Helmholtz resonator to a tensile structure, is characterized in that... The piezoelectric induction module includes a piezoelectric beam, a piezoelectric sheet, and a tension structure; One end of the piezoelectric beam is a vertically installed support column; the piezoelectric beam extends from the middle of the support column to one side and remains perpendicular to the support column. The tension structure is fixed to one end of the piezoelectric beam near the support column; The piezoelectric sheet is attached to the top of the tension structure, and the width of the piezoelectric sheet is the same as the width of the beam.

5. The acoustic energy harvesting device according to claim 4, which couples a nonlinear Helmholtz resonator to a tensile structure, is characterized in that... The tension structure was designed as a hexagonal negative Poisson's ratio superstructure.

6. The acoustic energy harvesting device according to claim 1, which couples a nonlinear Helmholtz resonator to a tensile structure, is characterized in that... The sound pressure gain and resonant frequency of a Helmholtz resonator depend on the geometric parameters of the neck and cavity of the resonator. By designing the geometric parameters, the Helmholtz resonator can generate sound pressure gain in the required frequency range.

7. The acoustic energy harvesting device according to claim 1, which couples a nonlinear Helmholtz resonator to a tensile structure, is characterized in that... In the long-wavelength limit, the motion of air particles in the neck of a Helmholtz resonator exhibits a nonlinear motion state; this motion state includes single-period, multi-period bifurcation, quasi-period, and chaotic motion states.

8. The acoustic energy harvesting device according to claim 1, which couples a nonlinear Helmholtz resonator to a tensile structure, is characterized in that... By adjusting the vibration mode and resonant frequency of the piezoelectric beam, the optimal resonant mode of the piezoelectric beam is matched with the acoustic resonance of the Helmholtz resonator, thereby achieving a dual gain in the vibration of the piezoelectric beam.

9. The acoustic energy harvesting device by coupling a nonlinear Helmholtz resonator with a tensile structure according to claim 1, characterized in that, The tension structure causes the longitudinal and transverse stresses of the piezoelectric beam to have a superposition effect rather than cancel each other when it is excited, resulting in a larger stress distribution and improving the gain of electrical energy output.

10. An acoustic absorption component, characterized in that, It includes multiple acoustic energy harvesting devices as described in any one of claims 1-9; the acoustic energy harvesting devices are arranged in noisy environments such as nightclubs, bars or highways to absorb noise and convert it into electrical energy to power miniaturized wireless sensing devices.

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