Asymmetric force-electric coupling metamaterial vibration reduction and power generation structure and method

Abstract

The application discloses a kind of asymmetric force-electric coupling metamaterial vibration damping, power generation structure and method, including several sections, each section is by several periodic units, the periodic unit includes sandwich layer, inductor circuit and load circuit, both upper and lower surfaces of the sandwich layer are provided with cover layer, a plurality of piezoelectric wafer is equipped outside the cover layer, the piezoelectric wafer located above sandwich layer is upper wafer, the piezoelectric wafer located below sandwich layer is lower wafer, the load circuit is connected with piezoelectric wafer by inductor circuit, the thickness of all upper wafers is same, the thickness of lower wafer in the same section is same, the thickness of lower wafer in different sections is different, to form the gradient classification of each section, this structure can simultaneously realize the multiple functions of low frequency, broadband vibration damping and power generation, and can well solve the defects that force-electric coupling metamaterial low-frequency band gap is narrow and band gap characteristics depend on large inductance element.

Description

Technical Field

[0001] This invention relates to a vibration reduction and power generation device, and more particularly to a structure and method for vibration reduction and power generation using an asymmetric force-electric coupling metamaterial. Background Technology

[0002] Low vibration and low noise are crucial technical indicators for modern industrial development. Vibration and noise control not only ensure the safety and reliability of industrial equipment structures but also provide better environmental comfort. After decades of development, my country's vibration control technology has made some progress, but the suppression of low-frequency broadband vibrations below 500 Hz remains a major problem to be solved in engineering. In the field of structural health monitoring technology, most wireless sensor nodes are currently powered by chemical batteries, leading to an increasingly acute conflict between the node's lifespan and the limited battery capacity. On the one hand, sensor nodes in these networks are often small in size, making it impossible to configure large-capacity batteries, thus limiting their lifespan; on the other hand, frequent battery replacements also bring a huge workload to the maintenance of the wireless network, indirectly increasing the cost of network deployment.

[0003] In recent years, some scholars have proposed structural devices for low-frequency vibration reduction and power generation using metamaterials. These devices utilize the vibration reduction mechanism of local resonance in metamaterials to collect vibration energy and power wireless sensing elements. However, in terms of effectiveness, the related designs have certain shortcomings. For example, the mechanical oscillator metamaterial structure uses a passive mechanical oscillator structure. Once the structure is determined, it is difficult to adjust the vibration suppression and power generation characteristics according to the requirements. Moreover, most mechanical oscillator metamaterial systems can only operate in different frequency ranges for vibration reduction and power generation, meaning they cannot achieve both functions simultaneously. Furthermore, for existing electromechanical oscillator-coupled metamaterials for low-frequency vibration reduction and power generation, there is a drawback that large inductance components are required to achieve the low-frequency bandgap. Summary of the Invention

[0004] The technical objective of this invention is to address the shortcomings of the prior art by providing a structure and method for vibration reduction and power generation using an asymmetric electromechanical coupling metamaterial.

[0005] The technical solution adopted by this invention to solve its technical problem is: an asymmetric force-electric coupling metamaterial structure and method for vibration reduction and power generation, including several segments, each segment being composed of several periodic units. The periodic unit includes a sandwich layer, an inductive circuit, and a load circuit. A cover layer is provided on both the upper and lower surfaces of the sandwich layer. Several piezoelectric wafers are provided outside the cover layer. The piezoelectric wafers located above the sandwich layer are upper wafers, and the piezoelectric wafers located below the sandwich layer are lower wafers. The load circuit is connected to the piezoelectric wafers through the inductive circuit. All upper wafers have the same thickness, the lower wafers in the same segment have the same thickness, and the lower wafers in different segments have different thicknesses, thereby forming a gradient classification of each segment.

[0006] Let the total number of segments be S, and the specific segment number be n, where n = 1, 2, ..., S. Let the thickness of the upper wafer be h0, where 0.1 ≤ h0 ≤ 0.2 mm. Let the thickness of the lower wafer within each segment be... ①, among which m is a natural number and m≥2, according to the resonant frequency domain of the electromechanical localized oscillator ②, If the capacitance is the inherent capacitance of the piezoelectric crystal, then =C0+C n C0 is the inherent capacitance of the upper chip, C n This corresponds to the inherent capacitance of the lower wafer in the segment. , If the frequency range of the vibration source is [f1, fs], and the inductance of the piezoelectric crystal is L < 1H, then the inherent capacitance of the piezoelectric crystal in the first segment is... + The inherent capacitance of the piezoelectric crystal in the last segment + Where A = b * k, A is the area of ​​the piezoelectric crystal electrode, 15 ≤ b ≤ 30 mm, 35 ≤ k ≤ 50 mm, let the area of ​​the piezoelectric crystal electrode in formula ② be... = f= To obtain the thickness h1 of the lower wafer in the first segment, let the thickness h1 in formula ② be... =C s f = f s The thickness h of the lower wafer in the last segment is obtained. s Thus, the range of gradient thickness variation Δh = h1 - h is obtained. s Finally, by substituting the sum of h1 and Δh into formula ①, the thickness h of the lower wafer in each segment can be obtained. n .

[0007] Further improvement: Let m=2, then .

[0008] Further improvements: ,but .

[0009] Advantages of this invention: This structure can simultaneously achieve multiple functions of low-frequency, broadband vibration reduction and power generation, and effectively solves the defects of narrow low-frequency bandgap and bandgap characteristics dependent on large inductors in mechanocoupled metamaterials. It utilizes the low-frequency elastic wave bandgap characteristics of multifunctional mechanocoupled metamaterials to suppress or weaken the propagation of low-frequency vibrations. Simultaneously, an energy harvesting circuit is introduced to collect the mechanical energy localized within the electromechanical localized oscillator of the mechanocoupled metamaterial and use it as electrical input for low-power wireless network nodes. This provides a new solution for low-frequency, broadband vibration suppression and energy supply for wireless network nodes in structural health monitoring in engineering. Compared to conventional symmetrical wafer structures, under the same oscillator mass and electrical parameters, asymmetrical wafer structures will exhibit lower frequency bandgap junctions. Furthermore, as future equipment develops towards intelligence, materials and structures are required to have multifunctional and adaptive characteristics. The equivalent properties and mechanical properties of mechanocoupled metamaterials can be controlled by an external electric field, possessing the potential to achieve multifunctionality and adaptability. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the present invention.

[0011] Figure 2 This is a schematic diagram of the structure of a single periodic unit of the present invention.

[0012] Figure 3 This is the vibration transmission curve in an embodiment of the present invention.

[0013] Figure 4 This is the total output power curve of the electricity in the embodiment of the present invention.

[0014] Figure 5 It is the vibration transmission curve of a symmetrical electromechanical coupling metamaterial.

[0015] Figure 6 It is the total output power curve of the symmetrical electromechanical coupling metamaterial.

[0016] In the diagram: sandwich layer 1, cover layer 2, piezoelectric wafer 3, inductor circuit 4, load circuit 5, full-bridge rectifier 51, storage capacitor 52, load 53. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings.

[0018] A structure and method for vibration reduction and power generation using an asymmetric electromechanical coupling metamaterial include several segments, each segment containing several periodic elements of identical electromechanical localized oscillators. The attenuation effect of vibration within the bandgap of each segment can be controlled by adjusting the number of identical periodic elements. Figure 1 For clarity, only two periodic units are shown in each segment. Each periodic unit includes a sandwich layer 1, an inductor circuit 4 (L), and a load circuit 5. Covering layers 2 are provided on both the upper and lower surfaces of the sandwich layer 1. Several piezoelectric wafers 3 are provided outside the covering layers 2. The piezoelectric wafers 3 located above the sandwich layer 1 are upper wafers, and the piezoelectric wafers 3 located below the sandwich layer 1 are lower wafers. The load circuit 5 is connected to the piezoelectric wafers 3 through the inductor circuit 4. All upper wafers have the same thickness, the lower wafers in the same segment have the same thickness, and the lower wafers in different segments have different thicknesses, thus forming a gradient classification of each segment. The load circuit 5 consists of a full-bridge rectifier 51, a storage capacitor 52, and a load 53.

[0019] Let the total number of segments be S, and the specific segment number be n, where n = 1, 2, ..., S. Let the thickness of the upper wafer be h0, where 0.1 ≤ h0 ≤ 0.2 mm. Let the thickness of the lower wafer within each segment be... ①, among which m is a natural number and m≥2, when m=2, At this time, the attenuation area and power generation area of ​​the vibration within the bandgap are at their maximum, according to the resonant frequency domain of the electromechanical localized oscillator. ②, If the capacitance is the inherent capacitance of the piezoelectric crystal, then =C0+C n C0 is the inherent capacitance of the upper chip, C n This corresponds to the inherent capacitance of the lower wafer in the segment. , If the frequency range of the vibration source is [f1, f2], then... s The inductance of the piezoelectric crystal is L < 1H, and the inherent capacitance of the piezoelectric crystal in the first segment is... + The inherent capacitance of the piezoelectric crystal in the last segment + Where A = b * k, A is the area of ​​the piezoelectric crystal electrode, 15 ≤ b ≤ 30 mm, 35 ≤ k ≤ 50 mm, let the area of ​​the piezoelectric crystal electrode in formula ② be... = f= To obtain the thickness h1 of the lower wafer in the first segment, let the thickness h1 in formula ② be... =C s f = f s The thickness h of the lower wafer in the last segment is obtained. sThus, the range of gradient thickness variation Δh = h1 - h is obtained. s Finally, by substituting the values ​​of h1 and Δh into formula ①, the thickness h of the lower wafer in each segment can be obtained. n .

[0020] To better arrange the number of segments, let ,but .

[0021] Its working principle is as follows: First, in practical applications, the first method is to connect the vibration source to the sandwich layer; the second method is to directly attach the piezoelectric crystal to the vibration source, thus eliminating the need for the sandwich layer and the capping layer. Each segment contains several periodic units of the same local oscillator to improve the attenuation effect of vibration within the bandgap. To lower the center frequency of each resonant bandgap, each pair of asymmetric piezoelectric crystals adopts a parallel connection mode; therefore, the polarization directions of the asymmetric piezoelectric crystals are the same. Furthermore, to better realize the multifunctional characteristics of the metamaterial's low-frequency broadband, the thickness of the crystal under the local oscillator between each segment maintains a fractional-order gradient distribution.

[0022] When performing vibration reduction and power generation, the vibration reduction mechanism mainly relies on the low-frequency elastic wave bandgap characteristics of the electromechanical coupling metamaterial to suppress or weaken the propagation of low-frequency vibrations; the power generation mechanism utilizes the positive piezoelectric effect of the piezoelectric crystal to convert the mechanical energy in the matrix into the electrical energy of the piezoelectric crystal, providing electrical energy to each node.

[0023] Example 1: A transverse displacement excitation is applied to the left end face of a force-electro-coupled metamaterial beam. The displacement excitation amplitude is 1 mm, the excitation frequency range is 390-500 Hz, the inductance L = 0.33 H, q = 1 / 2, h0 = 0.1 mm, A = 20 mm * 45 mm, the load R = 100 kΩ, the number of segments S = 11, the periodic element t = 3 within each segment, and the total beam length l = 2140 mm. Under these initial parameters, the thickness h of the lower wafer in each segment is obtained using formula ①. n After rounding, we get h1 = 0.5 mm. 11 =0.1mm, simulation experiments were conducted using the above parameters. Figure 3 and Figure 4 Frequency response curves for vibration transmission and total output power of the metamaterial are presented respectively. Figure 3 The vibration transmission frequency response curve shows that there is significant attenuation of the vibration in the 390-500Hz frequency range. Figure 4 The total output power frequency response curve shows that it exhibits a continuous wideband power generation effect in the 390-500Hz frequency range.

[0024] Example 2: Referring to the thickness values ​​of the upper and lower piezoelectric wafers in the first segment of Example 1, the total thickness of the upper and lower piezoelectric wafers in the first segment is 0.6 mm. Based on this, a symmetrical electromechanical coupling metamaterial structure is constructed, with the thickness of all segmented piezoelectric wafers set to 0.3 mm. All other parameters are consistent with Example 1. Simulation experiments are conducted using these parameters. Figure 5 and Figure 6 Symmetrical frequency response curves for vibration transmission and total output power of the electromechanical coupled metamaterial are presented. Figure 5 The vibration transmission frequency response curves show that in the 480-515Hz frequency range, the vibration exhibits significant attenuation due to the band gap, while in the 390-480Hz range, the vibration propagates almost without attenuation. Correspondingly, the vibration is transmitted through a frequency response curve that is significantly different from the frequency response curves observed in the frequency range. Figure 6 The total output power frequency response curve shows that the metamaterial exhibits better power generation performance in the bandgap frequency band. Compared with Example 1, the symmetric mode bandgap has a narrower bandwidth and a higher bandgap position. Therefore, the metamaterial structure proposed in this invention shows certain advantages in vibration reduction and power generation performance.

[0025] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A structure for vibration reduction and power generation using an asymmetric electromechanical coupling metamaterial, characterized in that: It includes several segments, each segment consisting of several periodic units. Each periodic unit includes a sandwich layer, an inductor circuit, and a load circuit. A cover layer is provided on both the upper and lower surfaces of the sandwich layer. Several piezoelectric wafers are provided outside the cover layer. The piezoelectric wafers located above the sandwich layer are upper wafers, and the piezoelectric wafers located below the sandwich layer are lower wafers. The load circuit is connected to the piezoelectric wafers through the inductor circuit. All upper wafers have the same thickness. The lower wafers in the same segment have the same thickness. The lower wafers in different segments have different thicknesses, thus forming a gradient classification of each segment. Let the total number of segments be S, and the specific segment number be n, where n = 1, 2, ..., S. Let the thickness of the upper wafer be h0, where 0.1 ≤ h0 ≤ 0.2 mm. Let the thickness of the lower wafer within each segment be... ①, among which m is a natural number, and m≥2, according to the resonant frequency domain of the electromechanical localized oscillator. ②, If the capacitance is the inherent capacitance of the piezoelectric crystal, then =C0+C n C0 is the inherent capacitance of the upper chip, C n This corresponds to the inherent capacitance of the lower wafer in the segment. , If the frequency range of the vibration source is [f1, f2], then... s The inductance of the piezoelectric crystal is L < 1H, and the inherent capacitance of the piezoelectric crystal in the first segment is... + The inherent capacitance of the piezoelectric crystal in the last segment + Where A = b * k, A is the area of ​​the piezoelectric crystal electrode, 15 ≤ b ≤ 30 mm, 35 ≤ k ≤ 50 mm, let the area of ​​the piezoelectric crystal electrode in formula ② be... = f= To obtain the thickness h1 of the lower wafer in the first segment, let the thickness h1 in formula ② be... =C s f = f s The thickness h of the lower wafer in the last segment is obtained. s Thus, the range of gradient thickness variation Δh = h1 - h is obtained. s Finally, by substituting the values ​​of h1 and Δh into formula ①, the thickness h of the lower wafer in each segment can be obtained. n .

2. The asymmetric electromechanical coupling metamaterial structure for vibration reduction and power generation according to claim 1, characterized in that: Let m=2, then .

3. The asymmetric electromechanical coupling metamaterial structure for vibration reduction and power generation according to claim 1, characterized in that: make ,but .

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