Hull Composite Wave-Damping Base Based on Acoustic Black Hole Effect

Abstract

The present invention discloses a hull composite wave-blocking base based on the acoustic black hole effect. The hull composite wave-blocking base includes: a base panel, a base bottom plate, a base web and a base bracket. The base web is located between the base panel and the base bottom plate; the base bracket is configured to be perpendicular to the base panel, the base bottom plate and the base web at the same time; wherein, a plurality of acoustic black hole structures are arranged on the base web and / or the base bracket, and the plurality of acoustic black hole structures are arranged in at least three straight lines, and the acoustic black hole structures on any two adjacent straight lines are periodically arranged according to different arrangement rules. According to the hull composite wave-blocking base of the present invention, by arranging a plurality of acoustic black hole structures and arranging the acoustic black hole structures in a certain arrangement manner, high-efficiency vibration energy absorption can be achieved, thereby achieving the purpose of vibration reduction and noise reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of acoustic optimization design of ship structures, and particularly to a hull composite wave-blocking pedestal based on the acoustic black hole effect. Background Art

[0002] Traditional ship pedestal structures are mainly used to bear the weight of equipment. When designing, factors such as structural strength and installation convenience are mainly considered. The common structure is composed of a panel, a web, and a bracket, and its acoustic performance is basically not considered.

[0003] With the improvement of the overall ship acoustic index requirements, the potential of elastic vibration isolation has been deeply explored, but it still cannot meet the requirements. Usually, the pedestal is a bridge for the vibration of equipment to be transmitted to the hull. Therefore, it is urgent to improve the pedestal and provide a hull composite wave-blocking pedestal based on the acoustic black hole effect to achieve high-efficiency vibration energy absorption so as to play a role in vibration reduction and noise reduction, and at least partially solve the above problems. Summary of the Invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further detailed in the Detailed Description section. The Summary of the Invention section of the present invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the protection scope of the claimed technical solution.

[0005] To at least partially solve the above problems, the present invention provides a hull composite wave-blocking pedestal based on the acoustic black hole effect. The hull composite wave-blocking pedestal includes: a pedestal panel; a pedestal bottom plate; a pedestal web located between the pedestal panel and the pedestal bottom plate; a pedestal bracket configured to be perpendicular to the pedestal panel, the pedestal bottom plate, and the pedestal web at the same time; wherein, a plurality of acoustic black hole structures are provided on the pedestal web and / or the pedestal bracket, and the plurality of acoustic black hole structures are arranged in at least three straight lines, and the acoustic black hole structures on any two adjacent straight lines are periodically arranged according to different arrangement rules.

[0006] Thus, a plurality of acoustic black hole structures are provided on the pedestal web and / or the pedestal bracket. The acoustic black hole realizes a gradual change in structural impedance through the change of the structural thickness, thereby causing a change in the propagation of bending waves in the structure and realizing the aggregation of waves in a local area of the structure. Moreover, the plurality of acoustic black hole structures are arranged in at least three straight lines, and the acoustic black hole structures on any two adjacent straight lines are periodically arranged according to different arrangement rules, which can achieve high-efficiency energy absorption to achieve the purpose of vibration reduction and noise reduction.

[0007] Preferably, between any acoustical black hole structures arranged in a straight line, acoustical discontinuities with different lengths are provided according to the different shortest distances between two adjacent acoustical black hole structures, so that any acoustical black hole structures arranged in a straight line are connected end to end through the acoustical discontinuities.

[0008] Thus, the effective wave blocking frequency of the acoustical discontinuity is usually above several hundred hertz. Through the cooperation of the acoustical black hole structure and the acoustical discontinuity, the effective vibration reduction frequency band can be broadened to the low frequency. That is, the periodically arranged acoustical black hole structures and acoustical discontinuities exacerbate the waveform conversion, scattering and reflection of the vibration wave in the hull grillage to suppress the transmission of vibration energy and further lower the cut-off frequency of vibration reduction.

[0009] Preferably, the acoustical black hole structure includes a recessed portion that is recessed inward from the surface of the base web and / or the base bracket. The recessed portion has a cavity in the shape of a truncated cone and a central region located at the center of the recessed portion.

[0010] Thus, through the above-mentioned acoustical black hole structure, high-efficiency vibration energy absorption can be achieved to achieve the purpose of vibration reduction and noise reduction.

[0011] Preferably, from the first edge where the central region is connected to the cavity to the second edge at the end of the recessed portion, the cavity wall is an exponentially varying region.

[0012] Thus, by setting the thickness distribution form of the acoustical black hole structure, the structural impedance can be changed, and it is easy to realize the manipulation of waves.

[0013] Preferably, at the second edge position, the thickness of the acoustical black hole structure along the recessed direction of the recessed portion is determined by the exponential function and the maximum diameter of the acoustical black hole structure.

[0014] Thus, the transition between the base web and / or the base bracket and the acoustical black hole structure is uniform, and wave reflection caused by discontinuity can be avoided as much as possible.

[0015] Preferably, a damping layer is provided on the surface of the base web and / or the base bracket and / or the base panel.

[0016] Thus, the damping layer converts vibration energy into heat energy by shear deformation, consumes most of the bending wave energy, produces a damping vibration reduction effect, and suppresses the high-frequency coincidence effect and low-frequency resonance.

[0017] Preferably, the thickness of the damping layer is 1-1.5 times the thickness of the base web and / or the base bracket.

[0018] Preferably, the acoustical discontinuity is a mounting member with a cross-section in the shape of T, H, L or rectangle.

[0019] Preferably, the material thickness of the contact part of the acoustic discontinuity with the base web and / or the base gusset is 0.5-1 times the thickness of the base web and / or the base gusset.

[0020] Preferably, the area formed by the projection of the acoustic discontinuity on the base web and / or the base gusset is configured not to completely cover the acoustic black hole structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following drawings of the present invention are used as part of the present invention to understand the present invention. The embodiments of the present invention are shown in the drawings and their descriptions are used to explain the principles of the present invention.

[0022] In the drawings:

[0023] Figure 1 is a three-dimensional view of a hull composite wave-damping base based on the acoustic black hole effect according to a preferred embodiment of the present invention;

[0024] Figure 2 is Figure 1 the front view of the hull composite wave-damping base based on the acoustic black hole effect shown;

[0025] Figure 3 is Figure 1 the side view of the hull composite wave-damping base based on the acoustic black hole effect shown;

[0026] Figure 4 is Figure 1 the schematic diagram of the acoustic black hole structure in the hull composite wave-damping base based on the acoustic black hole effect shown;

[0027] Figure 5 is along Figure 4 the sectional view taken along line A-A in, and at the same time shows the base web;

[0028] Figure 6 is Figure 5 the exponential function change region of the cavity in the acoustic black hole structure shown;

[0029] Figure 7 is the comparison data graph of the vibration acceleration level response of the base bottom plate of the hull composite wave-damping base based on the acoustic black hole effect according to a preferred embodiment of the present invention and the base of the prior art; and

[0030] Figure 8 is Figure 1 a single base segment in the hull composite wave-damping base based on the acoustic black hole effect shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that embodiments of the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the embodiments of the present invention.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprises" and / or "comprising" are used in this specification, they specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0033] Now, exemplary embodiments according to the present invention will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the present disclosure will be thorough and complete, and the concept of these exemplary embodiments will be fully conveyed to those of ordinary skill in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity, and the same reference numerals are used to denote the same elements, and thus their description will be omitted.

[0034] Hereinafter, Figures 1 to 7 a detailed description will be given of a hull composite wave-blocking base according to the present invention based on the acoustic black hole effect.

[0035] As Figure 1 shown, the hull composite wave-blocking base 100 according to the present invention based on the acoustic black hole effect mainly includes a base panel 110, a base bottom plate 120, a base web 130, and a base gusset 140. The base web 130 is located between the base panel 110 and the base bottom plate 120, and the base gusset 140 is configured to be perpendicular to the base panel 110, the base bottom plate 120, and the base web 130 simultaneously. A plurality of threaded holes or through holes 121 with a spacing in the range of 100 mm - 500 mm may be drilled around the base bottom plate 120, so that the base bottom plate 120 is installed at a set position of the hull by passing a connecting member through the threaded holes or through holes.

[0036] Specifically, a plurality of acoustic black hole structures 150 are provided on the base web 130 and / or the base gusset 140, and the plurality of acoustic black hole structures 150 are arranged in at least three straight lines, and the acoustic black hole structures 150 on any two adjacent straight lines are periodically arranged according to different arrangement rules.

[0037] In this embodiment, as Figure 1 and Figure 3 shown, a plurality of acoustic black hole structures 150 are provided on both the base web 130 and the base gusset 140. Now, referring to Figure 1 , the arrangement of the plurality of acoustic black hole structures 150 provided on the base web 130 will be described in detail.

[0038] As Figure 1 shown, the plurality of acoustic black hole structures 150 provided on the base web 130 are arranged in three rows. It can be understood that in other embodiments, the plurality of acoustic black hole structures 150 can be arranged in, for example, two rows, four rows, or arranged in multiple columns (such as 8 columns, 10 columns). The specific number of rows and columns can be set according to actual needs.

[0039] As can be seen from Figure 1 , the distances between the plurality of acoustic black hole structures 150 arranged in a straight line in the first row are equal. This arrangement where the distances between any two adjacent acoustic black hole structures 150 are equal can be understood as being arranged according to the first arrangement rule.

[0040] The plurality of acoustic black hole structures 150 arranged in a straight line in the second row can be roughly divided into several (such as 4) acoustic black hole structure units. Each acoustic black hole structure unit can include two or three or other appropriate numbers of acoustic black hole structures 150. The distance between any two adjacent acoustic black hole structure units is the first distance, and within each acoustic black hole structure unit, the distance between any two adjacent acoustic black hole units is a second distance different from the first distance. It can be understood that the acoustic black hole structures 150 arranged in this way are arranged according to a second arrangement rule different from the first arrangement rule.

[0041] The plurality of acoustic black hole structures 150 arranged in a straight line in the third row can be arranged according to a third arrangement rule different from the first and second arrangement rules. Different arrangement rules can be understood as: the distances between adjacent acoustic black hole structures 150 are different, and the cycle of repetition is different, which can be set according to actual needs accordingly.

[0042] Of course, as Figure 1 and Figure 2 shown, the plurality of acoustic black hole structures 150 arranged in a straight line in the third row can be arranged according to the same first arrangement rule as the first row. Although the plurality of acoustic black hole structures 150 arranged in a straight line in the first row and the third row are arranged according to the same arrangement rule, the arrangement methods of any two adjacent rows of the plurality of acoustic black hole structures 150 are different. Therefore, cross - cycle arrangement of all the acoustic black hole structures 150 provided on the base web 130 can be achieved. Therefore, the purpose of high - efficiency vibration energy absorption or vibration reduction and noise reduction can be achieved.

[0043] It can be understood that when a plurality of acoustic black hole structures 150 provided on the base web 130 are arranged in multiple straight columns (not shown in the figure), it is necessary to ensure that any two adjacent columns of acoustic black hole structures 150 are arranged in different arrangements, so that the cross-period arrangement of all the acoustic black hole structures 150 provided on the base web 130 can be realized, and further, high-efficiency vibration energy absorption can be achieved to achieve the purpose of vibration reduction and noise reduction.

[0044] Furthermore, in any straight-line arrangement of acoustic black hole structures 150, acoustic discontinuities 160 of different lengths are provided according to the different shortest distances between two adjacent acoustic black hole structures 150, so that any straight-line arrangement of acoustic black hole structures 150 is connected end to end through the acoustic discontinuities 160. As Figure 2 shown, since the distances between the multiple straight-line arranged acoustic black hole structures 150 in the first row and the third row are equal, the lengths of the acoustic discontinuities 160 between adjacent acoustic black hole structures 150 are equal. Since the distances between the multiple straight-line arranged acoustic black hole structures 150 in the second row are different, the lengths of the acoustic discontinuities 160 between adjacent acoustic black hole structures 150 are also different. By arranging the acoustic black hole structures 150 and the acoustic discontinuities 160 in each row to be connected end to end, high-efficiency vibration energy absorption can be achieved to achieve the purpose of vibration reduction and noise reduction.

[0045] Specifically, the acoustic discontinuity 160 can be a mounting member with a T-shaped, H-shaped, L-shaped or rectangular cross-section. In this embodiment, the acoustic discontinuity 160 is a mounting member with a T-shaped cross-section. And more specifically, the thickness of the part of the acoustic discontinuity 160 mounted on the base web 130 and / or the base gusset 140 is 0.5-1 times the thickness of the base web 130 and / or the base gusset 140.

[0046] Preferably, the area formed by the projection of the acoustic discontinuity 160 on the base web 130 is configured not to completely cover the acoustic black hole structure 150. It can be understood that Figure 2 the width dimension of the acoustic discontinuity 160 shown in

[0047] cannot be greater than the maximum diameter of the acoustic black hole structure 150. Figure 3 Next, with reference to

[0048] In this embodiment, as Figure 3As shown, a plurality of acoustic black hole structures 150 are arranged in a row, and an acoustic discontinuity 160 is provided between adjacent acoustic black hole structures 150. The acoustic black hole structure 150 and the acoustic discontinuity 160 are connected end to end through a portion extending in the width direction of the acoustic discontinuity 160. It can be understood that if the base gusset 140 is large enough, it can also be arranged in the same way as the plurality of acoustic black holes and the acoustic discontinuity 160 provided on the base web 130 described above. For the sake of brevity in writing, it will not be elaborated here.

[0049] It can be understood that Figure 1 If an acoustic black hole structure 150 and an acoustic discontinuity are provided on the surface of the base web 130 visible in [reference], then acoustic black hole structures 150 and / or acoustic discontinuities 160 can also be symmetrically provided on the opposite surface of the base web 130. Similarly, acoustic black hole structures 150 and / or acoustic discontinuities 160 can be provided on both opposite surfaces of the base gusset 140.

[0050] Furthermore, a damping layer can be provided on the surface of the base web 130 and / or the base gusset 140 and / or the base panel 110. Thus, the damping layer converts the vibration energy into heat energy by shear deformation, consumes most of the bending wave energy, produces a damping and vibration reduction effect, and suppresses the high-frequency coincidence effect and low-frequency resonance. Specifically, the thickness of the damping layer can be 1 - 1.5 times the thickness of the base web 130 and / or the base gusset 140.

[0051] Next, refer to Figures 4 to 6 to describe in detail the specific structure of the acoustic black hole structure 150.

[0052] As Figure 1 , Figure 4 and Figure 5 shown, the acoustic black hole structure 150 can include a recessed portion that is recessed inward from the surface of the base web 130 and / or the base gusset 140. The recessed portion has a cavity 151 in the shape of a frustum of a cone and a central region 152 located at the center of the recessed portion.

[0053] Specifically, as Figure 4 shown, from the first edge 153 where the central region 152 is connected to the cavity 151 to the second edge 154 at the end of the recessed portion ( Figure 4 in, the diameter of the first edge 153 is 16 mm, and the diameter of the second edge 154 is 80 mm), the cavity wall of the cavity 151 is a region that varies according to an exponential function. The exponential function is h(x) = ex m(The exponent m is not less than 2). Wherein, h is the shortest distance between the upper and lower surfaces of the cavity 151, x is the cross-sectional radius of the acoustic black hole structure 150, and e is determined according to the structural form. If in the thickness variation exponential function, h1 = 0.4 mm, x1 = 8 mm, m = 2, and e = 0.0625, then the shape and cross-section of the acoustic black hole within the range of x from 0 to 40 mm are as Figure 6 shown.

[0054] Reference Figure 5 , at the second edge position, the thickness of the acoustic black hole structure 150 along the depression direction of the depression part is equal to the thickness of the base web 130 (or the base gusset 140) where the acoustic black hole structure 150 is located. Thus, the transition between the base web 130 and / or the base gusset 140 and the acoustic black hole structure 150 is uniform, and wave reflection caused by discontinuity can be avoided as much as possible.

[0055] Next, the structural dynamics response problem of the base containing the acoustic black hole structure 150 of the present invention under time-domain load designed by the finite element method will be described in detail. Considering that at least 10 elements are included in each wavelength to ensure the calculation accuracy and the cost of each operation, a single base segment 101 is selected as the research object, as Figure 8 shown. The distance between the base webs 130 is 500 mm, the distance between the base panel 110 and the base bottom plate 120 is 480 mm, and the cross-section of the acoustic discontinuity 160 is a T-shaped beam of 36 mm * 36 mm * 6 mm. The radius of the uniform region (central region 152) of the acoustic black hole structure 150 is 8 mm, and the radius of the non-uniform region (ABH) is 40 mm. The thickness of the base web 130 and the base gusset 140 is 10 mm, the thickness of the base panel is 16 mm, the thickness of the mounting boss 111 and the bottom plate is 20 mm, and the thickness of the damping layer is 1 times the plate thickness. In order to calculate high-frequency data and reduce the calculation scale, one segment of the base is taken as the calculation and analysis object (which contains the periodic acoustic black hole structure 150, the acoustic discontinuity 160, and the damping layer). A single base segment contains 255395 nodes and 191692 high-quality hexahedral elements. A unit frequency-domain load (10 Hz - 8 kHz swept-frequency excitation) is applied to the central region of the upper panel of the base, and 5 points are selected at the same position on the base bottom plate 120 for energy averaging, and the acceleration responses of the base bottom plate 120 of the traditional base (without the periodic acoustic black hole structure 150, the acoustic discontinuity 160, and the damping layer) and the base of the present invention are compared respectively.

[0056] As Figure 7It can be seen that, compared with the traditional pedestal, the pedestal of the present invention has obvious vibration damping effects in the full frequency band (16 Hz - 6.3 kHz) (specific data can be seen in Table 1), and the vibration damping effect near the middle frequency band of 1250 Hz reaches more than 10 dB. It is worth noting that in the low frequency band below 200 Hz, there is still a vibration damping effect of more than 5 dB, realizing effective vibration damping of low frequency vibration waves and solving the problem of low frequency vibration damping that commonly exists in single acoustic treatment means. In the present invention, the introduction of the damping layer (acoustic coating) can increase the overall damping performance of the structure, and strengthen the acoustic black hole effect by reducing the reflection of bending waves from the acoustic black hole structure 150. The acoustic black hole structures 150 and the acoustic discontinuities 160 are arranged periodically, which intensifies the waveform conversion, scattering and reflection of vibration waves in the hull grillage. The scattered and reflected acoustic wave energy can be absorbed by the surrounding acoustic black holes twice or multiple times, further shifting down the cut-off frequency of vibration damping.

[0057] For the analysis of the pedestal bearing capacity, a three-directional load spectrum of 10 KN is applied to the central area of the pedestal panel 110. The maximum stresses of the pedestal of the present invention and the traditional pedestal are 153 Mpa and 145 Mpa respectively, with comparable bearing capacities, both meeting the strength criteria. The addition of the acoustic black hole structure 150 does not reduce the bearing capacity of the pedestal, and the area with the maximum stress distribution is not near the acoustic black hole structure 150, but at the junction of the pedestal web 130 and the pedestal bottom plate 120, which is in line with the actual situation. At the same time, it further shows that for some occasions where ordinary vibration isolators with high bearing requirements or special bearing directions cannot be used, the pedestal of the present invention is applicable and has good vibration damping ability while meeting the bearing requirements.

[0058] The hull composite wave-blocking pedestal based on the acoustic black hole effect according to the present invention consumes the vibration energy on the transmission path while supporting the power device, comprehensively utilizes the band gap effect, impedance mismatch and damping vibration damping design technologies of the acoustic black hole, intensifies the waveform conversion and reflection of vibration waves in the pedestal structure, so as to suppress the transmission of vibration energy, realize multi-composite vibration damping and significantly improve the vibration damping effect, has good economy and broad application prospects, and is applicable to the pedestal structures of various marine power equipment.

[0059] Due to the interaction of multiple vibration damping mechanisms, compared with the traditional pedestal structure type, the average vibration damping effect of the present invention can be increased by more than 10 dB in the low and middle frequency ranges, and the vibration damping effects on low-middle-high frequencies are more obvious, which has important engineering application value for vibration reduction and noise reduction in ship cabins. For places with compact installation space and small equipment vibration excitation sources, the installation space of vibration isolators can be saved, avoiding the defects of short service life and poor stability of the elastic support vibration damping system, and at the same time ensuring the vibration isolation efficiency for the excitation equipment. For equipment with large vibration excitation sources, it can be used in combination with elastic supports to further improve the vibration damping effect on the equipment.

[0060] Unless otherwise defined, the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the technical field of the present invention. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. Terms such as "arranged" that appear herein can either mean that one component is directly attached to another component or that one component is attached to another component through an intermediate member. Features described in one embodiment herein can be applied to another embodiment alone or in combination with other features, unless the feature is not applicable or otherwise stated in that other embodiment.

[0061] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are for illustrative and exemplary purposes only and are not intended to limit the present invention to the scope of the described embodiments. Those skilled in the art can understand that according to the teachings of the present invention, more variations and modifications can be made, and all such variations and modifications fall within the scope of protection required by the present invention.

Claims

1. A hull composite wave-blocking pedestal based on the acoustic black hole effect, Characterized in that, The hull composite wave-blocking pedestal includes: A pedestal panel; A pedestal bottom plate; A pedestal web, the pedestal web is located between the pedestal panel and the pedestal bottom plate; A pedestal bracket, the pedestal bracket is configured to be perpendicular to the pedestal panel, the pedestal bottom plate and the pedestal web at the same time; Wherein, a plurality of acoustic black hole structures are arranged on the pedestal web and / or the pedestal bracket, and the plurality of acoustic black hole structures are arranged in at least three straight lines, and the acoustic black hole structures on any two adjacent straight lines are periodically arranged according to different arrangement rules, Between any straight-line arranged acoustic black hole structures, acoustic discontinuities with different lengths are provided according to the different shortest distances between two adjacent acoustic black hole structures, so that any straight-line arranged acoustic black hole structures are connected end to end through the acoustic discontinuities, The width dimension of the acoustic discontinuity cannot be greater than the maximum diameter of the acoustic black hole structure, The acoustic discontinuity is a mounting member with a T-shaped, H-shaped, L-shaped or rectangular cross-section, A damping layer is provided on the surface of the pedestal web and / or the pedestal bracket and / or the pedestal panel.

2. The hull composite wave-blocking pedestal based on the acoustic black hole effect according to claim 1, Characterized in that, The acoustic black hole structure includes a recessed portion recessed inward from the surface of the pedestal web and / or the pedestal bracket, and the recessed portion has a cavity in the shape of a frustum of a cone and a central region located at the center of the recessed portion.

3. The hull composite wave-blocking pedestal based on the acoustic black hole effect according to claim 2, Characterized in that, From the first edge where the central region is connected to the cavity to the second edge at the end of the recessed portion, the cavity wall is a region with an exponential function change.

4. The hull composite wave-blocking pedestal based on the acoustic black hole effect according to claim 3, Characterized in that, At the second edge position, the thickness of the acoustic black hole structure along the recessed direction of the recessed portion is determined by the exponential function and the maximum diameter of the acoustic black hole structure.

5. The hull composite wave-blocking pedestal based on the acoustic black hole effect according to claim 1, Characterized in that, The thickness of the damping layer is 1-1.5 times the thickness of the pedestal web and / or the pedestal bracket.

6. The hull composite wave-blocking pedestal based on the acoustic black hole effect according to claim 1, Characterized in that, The material thickness of the contact part of the acoustic discontinuity with the pedestal web and / or the pedestal bracket is 0.5-1 times the thickness of the pedestal web and / or the pedestal bracket.

Images