Acoustic filter with bridge type structure
By introducing a bridge structure design into the acoustic filter, the problem of difficulty in forming a band gap in the low frequency range in the prior art is solved, and the adjustability of the width and position of the band gap is achieved, suitable for lightweight design, and production costs are reduced.
Patent Information
- Application Number
- CN202411888327.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-04-25
AI Technical Summary
Existing Lamb acoustic filters are difficult to form a band gap in the low frequency range, with a high band gap frequency and a heavier design structure, so they cannot effectively adjust the width and position of the band gap, resulting in poor adjustability of the band gap.
An acoustic filter with a bridge structure is designed, through periodically arranged acoustic metamaterial units, including a substrate plate, a scatterer and a bridge structure. The scatterer is embedded inside the substrate plate and connected through the bridge structure to adjust the length and position of the bridge structure to control the width and position of the band gap.
It realizes the formation of a broadband band gap in a lower frequency range, and the band gap frequency is reduced, which improves the adjustability of the band gap. The structural design is simple, the material is used less, and the overall weight is lighter. It is suitable for lightweight design, and the band gap is adjusted without adding additional materials, reducing production costs.
Smart Images
Figure CN119892005A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of acoustic filters, and in particular to an acoustic filter with a bridge structure. Background Art
[0002] Acoustic metamaterials are a class of artificial materials with periodic structures that can form a complete phononic band gap within a specific frequency range, thereby preventing elastic waves from propagating within this frequency range. With the deepening of research, more and more studies have begun to focus on the propagation of Lamb waves in periodic composite plates. In the prior art, two-dimensional phononic crystal plates mostly control the propagation of sound waves through periodically arranged short structures or surface resonators. However, the band gap frequency of these technologies is relatively high, and most of the technologies focus on phononic crystal systems with external surface resonators, and fail to make full use of the resonator structure inside the plate to adjust the band gap.
[0003] The disadvantages of conventional Lamb wave acoustic filters are mainly manifested in: low-frequency band gaps are difficult to achieve, the band gap frequency is high, and the design structure is heavy; the width and position of the band gap cannot be effectively adjusted, resulting in poor adjustability of the band gap; most Lamb wave acoustic filters increase the use of additional materials, resulting in a heavier system and are not suitable for lightweight design. Summary of the invention
[0004] Purpose of the invention: In view of the above problems, the purpose of the present invention is to provide an acoustic filter with a bridge-type structure, which can form a band gap in a lower frequency range, and effectively adjust the width and position of the band gap by adjusting the length and position of the bridge structure to extract the Lamb wave signal of the desired frequency band.
[0005] Technical solution: An acoustic filter with a bridge-type structure of the present invention comprises acoustic metamaterial units arranged periodically, wherein the acoustic metamaterial units comprise a substrate plate, a scatterer and a bridge-type structure, the scatterer is embedded in the interior of the substrate plate, there is a gap between the scatterer and the substrate plate, and the scatterer and the substrate plate are connected by the bridge-type structure.
[0006] Furthermore, by adjusting the length and position of the bridge structure, the width and position of the band gap of the acoustic filter can be controlled.
[0007] Furthermore, the material of the scatterer is a rigid material.
[0008] Furthermore, the base plate is made of elastic material.
[0009] Furthermore, the material of the bridge structure is a rigid material.
[0010] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:
[0011] 1. The present invention can form a broadband band gap in a relatively low frequency range. The frequency of the band gap is several dozen times lower than that of the traditional phononic crystal plate, and is particularly suitable for low-frequency noise control and vibration isolation;
[0012] 2. The present invention can accurately control the width and position of the band gap by adjusting the length and position of the bridge structure, thereby improving the adjustability of the band gap;
[0013] 3. The present invention has a simple structure design, uses less materials, and has a light overall weight, and is suitable for use in fields requiring lightweight design;
[0014] 4. The present invention can adjust the band gap by adjusting the bridge structure without adding additional materials, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a structural schematic diagram of an acoustic filter with a bridge structure;
[0016] Figure 2 is a cross-sectional schematic diagram of an acoustic filter;
[0017] Figure 3 is a cross-sectional schematic diagram of an acoustic metamaterial unit;
[0018] Figure 4 It is a structural schematic diagram of an acoustic filter with a bridgeless structure;
[0019] Figure 5 The energy band structure and frequency response curve of the acoustic filter with a bridgeless structure;
[0020] Figure 6 The energy band structure and frequency response curve of the acoustic filter with a bridge structure;
[0021] Figure 7 The structural diagram of the acoustic metamaterial unit when the bridge structure position is different;
[0022] Figure 8 The energy band structure and frequency response curve of the acoustic filter when h = 1mm;
[0023] Fig. 9 The energy band structure and frequency response curve of the acoustic filter when h = 5mm;
[0024] Fig.10 The energy band structure and frequency response curve of the acoustic filter when h = 7mm;
[0025] Fig.11 The energy band structure and frequency response curve of the acoustic filter when h = 9mm;
[0026] Fig.12The distribution of vocal band gap changes with the position of the bridge structure;
[0027] Fig.13 The structural diagram of the acoustic metamaterial unit with different bridge structure lengths;
[0028] Fig.14 The energy band structure and frequency response curve of the acoustic filter when l = 5mm;
[0029] Fig.15 The energy band structure and frequency response curve of the acoustic filter when l = 15mm;
[0030] Fig.16 The energy band structure and frequency response curve of the acoustic filter when l = 28mm;
[0031] Fig.17 The distribution of vocal band gap changes with the length of the bridge structure. DETAILED DESCRIPTION
[0032] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.
[0033] like Figure 1 FIG. 1 is a schematic diagram of the structure of an acoustic filter with a bridge structure according to this embodiment. Figure 2 The cross-sectional schematic diagram of the acoustic filter includes N acoustic metamaterial units arranged periodically. Each acoustic metamaterial unit includes a substrate, a scatterer and a bridge structure. In the figure, A represents the scatterer, B represents the substrate, and C represents the bridge structure. The scatterer is embedded in the substrate, and there is a gap between the scatterer and the substrate. The scatterer and the substrate are connected by the bridge structure.
[0034] In this example, the scatterer is a cube, and the Figure 1 In the rectangular coordinate system shown in , the x-axis is the direction of the periodic arrangement of the acoustic metamaterial, that is, the direction of sound wave propagation, the y-axis is the length direction of the substrate, and the z-axis is the vertical direction of sound wave propagation. The thickness a of the acoustic metamaterial unit in the y-direction is numerically equal to the lattice constant, and it can be infinitely extended in the z-direction.
[0035] like Figure 3 Figure 1 is a cross-sectional diagram of an acoustic metamaterial unit. The width and length of the scatterer are d and c, respectively, and the width and length of the bridge structure are w and l, respectively. h represents the distance between the center line of the bridge structure and the center line of the substrate in the y direction, and h can be used to characterize the position of the bridge structure.
[0036] Furthermore, by adjusting the length and position parameters of the bridge structure, the width and position of the band gap of the acoustic filter can be controlled.
[0037] Further, the material of the scatterer is a rigid material, such as steel. The material of the base plate is an elastic material, such as rubber. The material of the bridge structure is a rigid material, such as steel.
[0038] Embodiment 1
[0039] In the acoustic filter with a bridge structure described in this example, the base plate is made of rubber, and the scatterer and the bridge structure are made of steel. The distance between the scatterer and the base plate is b and remains unchanged. The values of the parameters are: a = 34 mm, b = 1 mm, c = d = 28 mm, w = 1 mm, l = 15 mm, h = 0 mm.
[0040] The acoustic filter with a bridge structure in this example is combined with Figure 4 Compared with the existing bridgeless acoustic filter shown in FIG. Figure 5 The band structure and frequency response curve of the acoustic filter without bridge structure are shown in Figure 2. Figure 5 As shown in the middle figure (a), when the acoustic filter is a bridgeless structure, there are seven energy bands in the frequency range of 0 to 2.5 kHz, and no band gap. To verify the correctness of the band structure analysis, the frequency response curve of the acoustic filter composed of 20 acoustic metamaterial units is calculated in this example. The results are as follows: Figure 5 As shown in (b), it can be clearly seen from the figure that the frequency response curve is basically consistent with the calculated results of the dispersion curve.
[0041] When the acoustic filter is connected in a bridge structure, the band structure and frequency response curve are as follows: Figure 6 As shown. Figure 6 As shown in the middle figure (a), when the acoustic filter has a bridge structure, it contains 8 energy bands in the frequency range of 0-2.5kHz, and involves two band gaps, as shown in the shaded area in the figure. The first band gap is between the third and fourth energy bands, with a frequency range of 0.223kHz to 0.774kHz and a band gap width of 0.551kHz; the second band gap is between the fifth and sixth energy bands, with a frequency range of 0.854kHz to 1.02kHz and a band gap width of 0.166kHz. Figure (b) is the calculated frequency response curve of the acoustic filter, from which it can be clearly seen that the frequency response curve is basically consistent with the calculated results of the dispersion curve.
[0042] pass Figure 5 and Figure 6 It can be found that with the introduction of the bridge structure, the acoustic filter can form a band gap in a lower frequency range.
[0043] Embodiment 2
[0044] In the acoustic filter with a bridge structure described in this example, the base plate is made of rubber, and the scatterer and the bridge structure are made of steel. The structural parameters in Example 1 are used, that is, the values of each parameter are: a = 34mm, b = 1mm, c = d = 28mm, w = 1mm, l = 15mm. The position parameter h of the bridge structure is changed within the range of 0mm to 10mm. In the implementation, four cases of h = 1mm, h = 5mm, h = 7mm, and h = 9mm are selected respectively. The structure is as follows Figure 7 shown.
[0045] When the bridge structure is moved along the positive direction of the y-axis to h = 1 mm, the resulting band structure is as follows: Figure 8 As shown in Figure (a), there are 9 energy bands involved in the band structure. From the right, there is a band gap between the third and fourth energy bands, as shown in the gray shadow part of the figure. The frequency range is 0.173-0.661kHz, the band gap width is 0.487kHz, and the fourth and fifth energy bands almost overlap. At the same time, the frequency domain response analysis is performed, and the frequency response curve is shown in Figure (b). The results show that the frequency response curve is basically consistent with the band gap result.
[0046] When the bridge structure is moved along the positive direction of the y-axis to h = 5 mm, the resulting band structure is as follows: Fig. 9 As shown in Figure (a), it can be observed that the lower sideband of the bandgap increases while the upper sideband decreases, resulting in a decrease in bandwidth. The frequency range is 0.276-0.5kHz, and the bandgap width is 0.224kHz. The frequency response curve obtained by frequency domain response analysis is shown in Figure (b). Figure 8 By comparison, it is found that the bandgap bandwidth is also reduced.
[0047] When the bridge structure is moved along the positive direction of the y-axis to h = 7 mm, the resulting band structure is as follows: Fig.10 As shown in Figure (a), the band gap in the low-frequency range is severely reduced, and a new band gap is opened between the eighth and ninth energy bands. The frequency response curve obtained by frequency domain response analysis is shown in Figure (b). The position of the band gap shown in the frequency response curve basically corresponds to the position in the dispersion curve diagram.
[0048] When the bridge structure is moved along the positive direction of the y-axis to h = 9 mm, the resulting band structure is as follows: Fig.11 As shown in Figure (a), the frequency response curve obtained by frequency response analysis is shown in Figure (b). It can be found that the band gap in the low-frequency range disappears, and the band gap width between the eighth and ninth energy bands increases as the position of the bridge structure continues to move toward the positive direction of the y-axis.
[0049] In order to more intuitively observe the influence of the position of the bridge structure on the band structure, Fig.12The upper and lower sidebands of the band gap change. The position of the band gap is shown in the shaded part of the figure. It can be seen from the figure that as h moves along the positive direction of the y-axis, the upper sideband of the band gap shows a downward trend, the lower sideband shows an upward trend, and the band gap width is gradually shrinking. At the same time, a new band gap is generated, the upper sideband of the new band gap shows an upward trend, the lower sideband shows a downward trend, and the band gap width increases.
[0050] In this example, by adjusting the position of the bridge structure, the frequency and width of the band gap in the acoustic filter changed significantly, verifying the regulating effect of the bridge structure position on the band gap.
[0051] Embodiment 3
[0052] In the acoustic filter with a bridge structure described in this example, the base plate is made of rubber, and the scatterer and the bridge structure are made of steel. The structural parameters of the first embodiment are adopted, that is, the values of each parameter are: a = 34mm, b = 1mm, c = d = 28mm, w = 1mm, h = 1mm, and the length parameter l of the bridge structure is changed within the range of 5mm to 28mm. In the implementation, three cases of l = 5mm, l = 15mm, and l = 28mm are selected respectively. Fig.13 shown.
[0053] When l = 5 mm, the resulting band structure is as follows Fig.14 As shown in Figure (a), there are 9 energy bands involved in the band structure, and a band gap appears between the third and fourth energy bands, with a frequency range of 0.126kHz to 0.559kHz and a band gap width of 0.433kHz. The frequency response curve obtained by frequency response analysis is shown in Figure (b), and the results show that the frequency response curve is basically consistent with the band gap calculation result.
[0054] When l = 15 mm, the resulting band structure is as follows Fig.15 As shown in Figure (a), the band structure involves 8 energy bands and two band gaps. The first band gap is located between the third and fourth energy bands, with a frequency range of 0.223kHz to 0.774kHz and a band gap width of 0.551kHz; the second band gap is located between the fifth and sixth energy bands, with a frequency range of 0.854kHz to 1.02kHz and a band gap width of 0.166kHz. The frequency response curve obtained by frequency response analysis is shown in Figure (b), and the results show that the frequency response curve is basically consistent with the band gap calculation results.
[0055] When l = 28 mm, the resulting band structure is as follows Fig.16As shown in Figure (a), the band structure involves 7 bands. Compared with the dispersion curve when l = 15mm, it is found that a new band gap appears at a higher frequency, while the width of the first band gap decreases and the width of the second band gap increases. The frequency response curve obtained by frequency response analysis is shown in Figure (b), and the results show that the frequency response curve is basically consistent with the band gap calculation results.
[0056] In order to more intuitively observe the influence of the position of the bridge structure on the band structure, Fig.17 The upper and lower sidebands of the band gap are shown as they change with the length of the bridge structure. It can be seen that when the length of the bridge structure is small, there is only one band gap in the frequency range of 0-3kHz. As the length of the bridge structure increases, new band gaps appear at higher frequencies.
[0057] In this example, by adjusting the length of the bridge structure, the frequency and width of the band gap in the acoustic filter changed significantly, verifying the regulating effect of the bridge structure length on the band gap.
Claims
1. An acoustic filter with a bridge structure, characterized in that: The invention comprises acoustic metamaterial units arranged along a periodic pattern, wherein the acoustic metamaterial units comprise a substrate plate, a scatterer and a bridge-type structure, the scatterer is embedded in the substrate plate, a gap exists between the scatterer and the substrate plate, and the scatterer and the substrate plate are connected by the bridge-type structure.
2. An acoustic filter with a bridge structure according to claim 1, characterized in that: By adjusting the length and position of the bridge structure, the width and position of the band gap of the acoustic filter can be controlled.
3. The acoustic filter with a bridge structure according to claim 1, characterized in that: The material of the scatterer is a rigid material.
4. The acoustic filter with a bridge structure according to claim 1, characterized in that: The material used for the base plate is elastic material.
5. The acoustic filter with a bridge structure according to claim 1, characterized in that: The material of the bridge structure is a rigid material.