Longitudinal vibration multi-mode coupling dual-band underwater acoustic transducer

Abstract

The invention relates to the field of underwater acoustic transducers, in particular to a longitudinal vibration multi-mode coupling dual-band underwater acoustic transducer which is vertically symmetrical and comprises a radiation head (1), a support ring (2), an inverted mass block and cantilever part (3), a driving vibrator (4), a central base (5) and a prestressed screw (6). The inverted mass block and the cantilever part (3) are connected to the back of the radiation head (1), and the inverted mass block and the cantilever part (3) are tightly connected with the supporting ring (2), the driving oscillator (4) and the center base (5) in sequence through the prestressed screw (6). By arranging the inverted mass block and the cantilever part (3), the position of a response notch point is changed, and multiple modes of the transducer are regulated and controlled to be coupled to form double frequency bands. The problem that radiation performance and broadband performance cannot be considered in the design of the broadband transducer is solved due to existence of the allowed notch response, multi-scene use of a single transducer is facilitated, and the broadband transducer can be applied to the fields of underwater acoustic communication, underwater detection and the like.

Description

Technical Field

[0001] The present invention relates to the field of underwater acoustic transducers, and in particular to a longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer. Background Art

[0002] In recent years, maritime defense has rapidly developed, with unmanned and intelligent systems becoming key trends. Unmanned platforms such as unmanned underwater vehicles (UUVs) and unmanned surface vessels (USVs) are gaining increasing attention in marine environments. Typically, these underwater platforms require a variety of sonar equipment covering different frequency bands to enable multi-functions such as detection, communication, and navigation. However, for small unmanned platforms, traditional solutions integrating multiple transducers are no longer feasible due to size and energy consumption limitations. There is an urgent need to miniaturize and enhance the functionality of these transducers.

[0003] However, there is currently a lack of single-unit transducer solutions that can operate stably over a wide frequency band. In 2011, Butler JL and Butler AL proposed a "single-ended excitation" method, using only half of the piezoelectric crystal stack for excitation. This method can excite the first three modes, forming a tri-resonant transducer (14–38 kHz). Although this method expands the frequency range, the fundamental frequency radiation is weak, and the broadband response has large fluctuations (over 10 dB). To address these issues, in 2021, Ji B et al. conducted in-depth research. They constructed a multi-port equivalent circuit model to address the multi-resonant excitation problem of the piezoelectric crystal stack and obtained the vibration velocity distribution of the radiating surface through numerical simulation. They discovered that the system has a "zero response point," which causes a notch in the transducer's transmit response curve, disrupting broadband formation. To mitigate this problem, they conducted extensive parameter sweep optimization design and developed a composite material ultra-wideband transducer with an operating frequency range of 100–1000 kHz. Despite the two-octave bandwidth, the in-band fluctuation exceeds 25 dB. Subsequently, the team developed a four-resonance transducer (20–80kHz) with better performance, but the fluctuations between its resonance peaks still exceeded 10dB.

[0004] Therefore, traditional ultra-wideband transducers still have obvious shortcomings in achieving multi-band and multi-scenario adaptability, and there is an urgent need to explore new multi-modal control mechanisms and structural design methods to achieve more reasonable frequency band division and response control.

[0005] Since optimizing a system's design necessarily requires increasing sensitivity in one frequency band at the expense of decreasing sensitivity in another, achieving multi-band performance requires precise design for each target frequency band, rather than relying on ultra-wideband coverage. This strategy allows for notched frequencies in non-operating bands, concentrating more energy on the operating band. Therefore, exploring the underlying principles of multimodal control and designing a multimodal transducer that can precisely control frequency bands, achieving high response at low frequencies and low fluctuations at wideband. Summary of the Invention

[0006] The object of the present invention is to overcome the above-mentioned defects of the prior art and thereby provide a longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer.

[0007] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0008] A longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer, comprising a radiation head, a support ring, an inverted mass block and a cantilever part, a driving vibrator, a central base and a prestressed screw;

[0009] The prestressed screw tightly connects the radiation head, support ring, driving vibrator and central base in sequence; a group of radiation head, support ring and driving vibrator are respectively arranged on both sides of the central base;

[0010] The mass and rigidity of the support ring are both smaller than those of the radiation head, and it plays an elastic supporting role in the structure;

[0011] The driving vibrator is axially connected to the interior of the underwater acoustic transducer;

[0012] The central base is perpendicular to the axial direction of the underwater acoustic transducer, and its mounting surface is a stepped concave surface or a flat surface;

[0013] The inverted mass block and cantilever part include several groups of parallel and evenly distributed inverted mass blocks and cantilever structures; the inverted mass block is axially connected to the back of the radiation head through several cantilevers, and the inverted mass block and cantilever part are located inside the underwater acoustic transducer.

[0014] One end of the cantilever is connected to the back of the radiation head through a thread or the like, and the other end passes through the inverted mass block and is fixed with a nut.

[0015] The mass and rigidity of the support ring are both smaller than those of the radiation head, and it plays an elastic supporting role in the structure;

[0016] The inverted mass block and cantilever part include one or more groups of parallel and evenly distributed cantilevers and inverted mass blocks, and the transducer includes at least one group of inverted mass blocks and cantilever structures in the axial direction;

[0017] The mounting surface of the central base is a stepped concave surface or a flat surface, and is made of a high-hardness material. The mounting surface is perpendicular to the axial direction of the underwater acoustic transducer.

[0018] The inverted mass and cantilever portion are always axially connected to the radiating head via the cantilever and are located within the transducer. By adjusting the weight of the inverted mass and the elasticity of the cantilever, the position of the notch frequency can be controlled, thereby adjusting the transducer's dual-band response.

[0019] As an improvement to the above transducer, the support ring may be a ring whose cross section changes with height, and may be made of a variety of materials.

[0020] As an improvement of the above-mentioned transducer, the inverted mass block and cantilever part include two inverted mass blocks and two groups of cantilevers continuously connected along the axial direction. The number of cantilevers can be selected according to needs and evenly distributed on the inverted mass block. The inverted mass block can be ring-shaped.

[0021] As an improvement to the above transducer, the dual-band transmission response of the transducer is a single resonance peak plus a broadband, or two broadbands.

[0022] As an improvement to the above transducer, the transducer transmits a response of a single resonance peak plus a broadband, or two single resonance peaks plus a broadband.

[0023] As an improvement to the above transducer, the radiation head is made of metal, preferably aluminum alloy, titanium alloy or other materials with a similar impedance to water. The radiation head is in the shape of a cone, cylinder, truncated cone, square, arc or polygon.

[0024] As an improvement to the above-mentioned transducer, the driving vibrator is two groups of axially symmetrical piezoelectric ceramic crystal stacks; the piezoelectric ceramic crystal stacks are formed by bonding an even number of piezoelectric ceramic sheets; the piezoelectric ceramic sheets are polarized along the thickness direction, and the polarization directions of two adjacent piezoelectric ceramic sheets are opposite. An electrode sheet is also provided between each two piezoelectric ceramic sheets, each group of piezoelectric ceramic sheets is electrically connected in parallel, and the two groups of piezoelectric ceramics are placed axially symmetrically according to the polarization direction of the piezoelectric ceramics.

[0025] As an improvement to the above transducer, the driving vibrators are two sets of axially symmetrical magnetostrictive vibrators, each comprising at least one magnetostrictive rod, a permanent magnet, and an excitation coil. The one or more magnetostrictive rods are positioned horizontally within the transducer along the axial direction, with their top and bottom connected to the radiation head and center base, respectively, via permanent magnets. The excitation coil is coaxially wound around the magnetostrictive rods.

[0026] As an improvement of the above transducer, the magnetostrictive rod is made of magnetostrictive material, and the permanent magnet material is a high magnetic energy product material. Preferably, the high magnetic energy product material is made of neodymium iron boron or samarium cobalt permanent magnet material.

[0027] As an improvement of the above-mentioned transducer, this transducer realizes transmission responses in both low-frequency and high-frequency bands through only one structure, thereby being adaptable to different usage scenarios.

[0028] As an improvement to the above transducer, the prestressed screw is used to compress multiple structural parts to ensure good displacement transmission during vibration.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] 1. The present invention utilizes the coupling relationship of multimodal resonance to set the third resonant system (the inverted mass block and the cantilever part) to the first-order resonant mode, and uses the radiation head and support ring as the second resonant system (rather than the traditional outermost radiation system) to radiate sound waves to the outside world. By adjusting the structural mass and stiffness, the position of the notch point can be flexibly controlled to achieve precise control of the dual frequency bands.

[0031] 2. The present invention rationally designs the notch point so that the transducer has both a stronger low-frequency radiation response within the working frequency band and maintains smaller fluctuations within the broadband range.

[0032] 3. In the longitudinal vibration multi-modal coupled dual-band underwater acoustic transducer provided by the present invention, the third resonance system is integrated on the back of the radiating head, which effectively reduces the overall volume of the transducer and is conducive to the miniaturization design and convenient deployment of the transducer.

[0033] 4. The longitudinal vibration multi-modal coupled dual-band underwater acoustic transducer provided by the present invention has dual-band radiation effects in both axial and radial directions within a wider frequency band (more than two octaves), which is conducive to expanding the use scenarios of the transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A cross-sectional view showing the structural schematic diagram of the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer of the present invention;

[0035] Figure 2 Schematic diagram of the structure of the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer of the present invention;

[0036] Figure 3 Schematic diagram of the principle of the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer of the present invention;

[0037] Figure 4The third-order longitudinal vibration mode within the operating frequency band of the transducer of the present invention and the bending mode of the radiation head, wherein (a) is the first-order resonant mode involved in the structural design of the present invention, which is controlled by the inverted mass block and the cantilever portion; (b) is the second-order resonant mode involved in the structural design of the present invention, which is mainly controlled by the radiation head and the support ring; (c) is the third-order resonant mode involved in the structural design of the present invention, which is mainly controlled by the driving vibrator; (d) is the bending mode to be avoided in the structural design of the present invention, which is mainly controlled by the shape and size of the radiation head;

[0038] Figure 5 A single resonance peak and a broadband dual-band transmission voltage response curve are formed for the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer of the present invention;

[0039] Figure 6 This is a cross-sectional view of a schematic diagram of a structure of two sets of continuously connected inverted mass blocks and cantilevers in the present invention. In this case, the transducer can form two single resonance peaks and a broadband transmission response characteristic;

[0040] Figure 7 This is a cross-sectional view of a schematic diagram of a transducer structure in the present invention, in which the support ring is composed of three rings whose cross sections change with height. In this case, the transducer can form two broadband transmission response characteristics;

[0041] Figure 8 This is a cross-sectional view of the structural schematic diagram of the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer in which the driving vibrator is driven by a magnetostrictive rod in the present invention.

[0042] Figure 9 The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer of the present invention forms two single resonance peaks and a broadband transmission voltage response curve.

[0043] Figure 10 Two broadband transmission voltage response curves are formed for the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer of the present invention.

[0044] Figure ID:

[0045] 1. Radiating head; 2. Support ring; 3. Inverted mass block and cantilever part; 4. Driving vibrator; 5. Center base; 6. Prestressed screw; 7. Magnetostrictive rod; 8. Permanent magnet; 9. Excitation coil. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings.

[0047] Combine Figure 1-2As shown, a longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer, the transducer is symmetrical in the upper and lower parts, including a radiation head 1, a support ring 2, an inverted mass block and a cantilever part 3, a driving vibrator 4, a central base 5 and a prestressed screw 6. The inverted mass block and the cantilever part 3 are connected to the back of the radiation head 1, and the prestressed screw 6 tightly connects them with the support ring 2, the driving vibrator 4 and the central base 5 in turn. The present invention changes the position of the response notch point by setting the inverted mass block and the cantilever part 3, and regulates the coupling of multiple modes of the transducer to form a dual-band. Allowing the existence of notch response solves the problem that the radiation performance and broadband performance cannot be taken into account at the same time in the design of wide-band transducers, which is conducive to the use of a single transducer in multiple scenarios, and can be applied to underwater acoustic communications, underwater detection and other fields.

[0048] The working principle of the longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer disclosed in the present invention is as follows:

[0049] Figure 3 This is the physical model of the multi-resonant oscillator of the longitudinal vibration multi-modal coupling dual-band underwater acoustic transducer of the present invention. The mass and stiffness of the driving oscillator are equivalent to M1 and K1, the radiation head and the support ring are equivalent to M2 and K2, and the inverted mass block and the cantilever part are equivalent to M3 and K3. Since for this three-resonance system (three-spring three-mass model), when the excitation force is applied to M1, the notch frequency point of the mass block M2 of the second resonant system is the pole of the third independent subsystem. With the three-resonance system as the design goal, considering applying excitation to the first mass block, at this time, the second mass block has a zero point of 3-1-|2-1|=1. The zero point frequency is determined by the subsystem where the third mass block is located. At this time, by adjusting the zero point position to the middle of the first and second order resonances through K3 and M3, a peak-wideband dual-band vibration velocity response can be formed.

[0050] In the past, almost all longitudinal vibration transducers used the outermost mass block as the radiation head to radiate sound waves, because it is at the outermost periphery and needs to be in direct contact with water. In order to achieve a dual-band effect using the second mass block as the radiation head, the present invention hangs the third mass block and the spring upside down behind the second mass block. From the analysis of vibration characteristics, the vibration behavior of the three mass blocks M1, M2, and M3 will not be affected in any way. The only difference is that the expansion and contraction state of the spring is opposite to that of the original model. This is exactly what the present invention does. Figure 1 The reason why the inverted mass block and the cantilever part 3 described above need to be axially connected to the back of the radiation head 1 through the cantilever is as follows.

[0051] Figure 4The third-order longitudinal vibration mode of the transducer within the operating frequency band and the bending mode of the radiating head are shown. In the design, in order to reduce the influence of the bending mode on the dual-band radiation effect, the thickness and radius of the radiating head are adjusted to make the resonant frequency of the bending mode away from the operating range while keeping the mass of the radiating head basically unchanged. At this time, the axial and radial transmission voltage responses of the transducer are as follows: Figure 5 As shown, the low frequency has a higher radiation response, and the broadband part has a small fluctuation (less than 6dB).

[0052] Example 1

[0053] Combine Figure 1 and Figure 2 A longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer includes a radiation head 1 and a support ring portion 2, an inverted mass block and a cantilever portion 3, a driving vibrator 4, a central base 5, and a prestressed screw 6. The inverted mass block and cantilever portion 3 are connected to the back of the radiation head 1 by means of threads or other means. The prestressed screw 6 tightly connects them to the support ring 2, the driving vibrator 4, and the central base 5 in sequence. A set of radiation heads 1, support rings 2, and driving vibrators 4 are respectively arranged on both sides of the central base 5.

[0054] The support ring 2 has a smaller mass and stiffness than the radiation head 1 and plays an elastic supporting role in the structure;

[0055] The underwater acoustic transducer includes two groups of inverted mass blocks and cantilever structures in the axial direction; one group is arranged on the back of a radiation head 1, and each group of inverted mass blocks and cantilever structures has multiple parallel and evenly distributed cantilevers and an inverted mass block. One end of the cantilever is connected to the radiation head by a thread, and the other end passes through the annular inverted mass block and is fixed with a nut.

[0056] The central base 5 is a high-hardness material with a stepped concave surface or a flat surface, and its plane is perpendicular to the axial direction;

[0057] The inverted mass and cantilever portion 3 are always axially connected to the radiating head 1 via the cantilever. The inverted mass and cantilever portion 3 are located within the transducer. By adjusting the weight of the inverted mass and the elasticity of the cantilever, the location of the notch frequency can be controlled, thereby adjusting the transducer's dual-band response.

[0058] The radiation head 1 in this embodiment is made of aluminum alloy and has a truncated cone shape.

[0059] The driving oscillator in this embodiment comprises two upper and lower piezoelectric ceramic stacks, symmetrically arranged along the transducer's axis. Each stack is constructed from an even number of bonded piezoelectric ceramic sheets. The sheets are polarized along their thickness, with adjacent sheets polarized in opposite directions. An electrode sheet is positioned between each pair of piezoelectric sheets, and each set of piezoelectric ceramic sheets is electrically connected in parallel. The polarization directions of the two piezoelectric ceramic sheets are symmetrical along the axis.

[0060] In this embodiment, the support ring 2 is made of aluminum alloy with equal cross-section.

[0061] In addition to the piezoelectric ceramic crystal stack, the driving oscillator in this embodiment may also be made of a piezoelectric single crystal stack or other ferroelectric materials and antiferroelectric materials.

[0062] In addition to being made of aluminum alloy, the radiation head 1 and the support ring 2 in this embodiment can also be made of titanium alloy or other alloy materials. In addition to using a truncated cone-shaped radiation head, the radiation head 1 can also use a conical, cylindrical, square, arc-shaped or polygonal radiation head.

[0063] The axial and radial voltage responses of the transducer are as follows: Figure 5 As shown, the low frequency has a higher radiation response, and the broadband part has a small fluctuation (less than 6dB).

[0064] Example 2

[0065] The structure is basically the same as that of Example 1, except that:

[0066] Combine Figure 6 In this embodiment, the back of a radiation head 1 is connected to an inverted mass block and a cantilever part 3, and an inverted mass block and a cantilever part 3 include two groups of parallel and evenly distributed inverted mass blocks and cantilever structures; the first group of inverted mass blocks is connected to the radiation head 1 through the cantilever, and the second group of inverted mass blocks is connected to the inverted mass blocks of the first group through the cantilever.

[0067] Each group of inverted mass blocks and cantilever structures has multiple parallel and evenly distributed cantilevers and an inverted mass block. One end of the cantilever is connected to the radiation head or the inverted mass block through a thread, and the other end passes through the annular inverted mass block and is fixed with a nut.

[0068] Combine Figure 9 In this embodiment, the size of the two inverted mass blocks and the stiffness of the cantilever can be symmetrically adjusted to control the transducer to achieve two single resonance peaks and a broadband transmission response characteristic.

[0069] Example 3

[0070] The structure is basically the same as that of Example 1, except that:

[0071] Combine Figure 7In this embodiment, the support ring 2 is composed of three rings whose cross-sections change with height. The middle part of the ring with a larger cross-section is made of copper alloy, while the two parts with small cross-sections are made of aluminum alloy.

[0072] Combine Figure 10 The transducer of this embodiment has four resonance peaks. By controlling the inverted mass block and the cantilever part 3 to move the notch frequency to between the second and third resonance frequencies, the transducer can achieve two broadband transmission response characteristics. In this embodiment, due to the change in directivity, the radial transmission dual broadband effect is better.

[0073] In this embodiment, in addition to the above materials, the support ring 2 may also be made of stainless steel or other high-density materials for the portion with a larger cross-section, and titanium alloy or other lightweight metal materials for the portion with a smaller cross-section.

[0074] In this embodiment, the support ring 2 may be formed integrally from the same material such as copper alloy or aluminum alloy, in addition to being made of different materials.

[0075] Example 4

[0076] The structure is basically the same as that of Example 1, except that:

[0077] Combine Figure 8 In this embodiment, the driving vibrators 4 are two sets of axially symmetrical magnetostrictive vibrators. The magnetostrictive vibrators include at least one magnetostrictive rod 7, a permanent magnet 8, and an excitation coil 9. The magnetostrictive rod 7 is made of a magnetostrictive material, and the permanent magnet 8 is made of a high-energy-product material. The one or more magnetostrictive rods 7 are positioned horizontally within the transducer along the axial direction. The top and bottom of the magnetostrictive rods 7 are connected to the radiation head 1 and the center base 5, respectively, via the permanent magnet 8. The excitation coil 9 is coaxially wound around the magnetostrictive rods. The magnetostrictive material is terbium-dysprosium-iron or iron-gallium material; the high-energy-product material is a permanent magnet such as neodymium-iron-boron or samarium-cobalt.

[0078] The transmission response frequency band characteristics of the transducer in this embodiment are the same as those in embodiment 1.

[0079] Any content not described in detail in the present invention can be based on conventional technical knowledge in the art.

[0080] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer, characterized in that: It comprises a radiation head (1), a support ring (2), an inverted mass block and a cantilever part (3), a driving vibrator (4), a central base (5) and a prestressed screw (6); The prestressed screw (6) tightly connects the radiation head (1), the support ring (2), the driving vibrator (4), and the central base (5) in sequence; a group of radiation heads (1), support rings (2), and driving vibrators (4) are respectively arranged on both sides of the central base (5); The support ring (2) has a smaller mass and stiffness than the radiation head (1), and plays an elastic supporting role in the structure; The driving vibrator (4) is axially connected to the interior of the underwater acoustic transducer; The central base (5) is perpendicular to the axial direction of the underwater acoustic transducer, and its mounting surface is a stepped concave surface or a flat surface; The inverted mass block and cantilever portion (3) comprises a plurality of groups of parallel and evenly distributed inverted mass blocks and cantilever structures; the inverted mass block is axially connected to the back of the radiation head (1) through a plurality of cantilevers, and the inverted mass block and cantilever portion (3) are located inside the underwater acoustic transducer.

2. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The cross section of the support ring (2) varies with height, and support rings of different heights are made of different materials.

3. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The inverted mass block and cantilever part (3) comprises two groups of parallel and evenly distributed inverted mass blocks and cantilever structures; the first group of inverted mass blocks is connected to the radiation head (1) via the cantilever, and the second group of inverted mass blocks is connected to the first group of inverted mass blocks via the cantilever.

4. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The radiation head (1) is made of aluminum alloy or titanium alloy; the radiation head (1) is in the shape of a cone, a column, a truncated cone, a square, an arc or a polygon.

5. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The driving vibrator (4) is a piezoelectric ceramic crystal stack; the piezoelectric ceramic crystal stack is formed by bonding an even number of piezoelectric ceramic sheets; the piezoelectric ceramic sheets are polarized along the thickness direction, and the polarization directions of two adjacent piezoelectric ceramic sheets are opposite. An electrode sheet is also provided between each two piezoelectric ceramic sheets, and the piezoelectric ceramic sheets are electrically connected in parallel; The piezoelectric ceramic crystal stacks on both sides of the central base (5) are placed axially symmetrically according to the polarization direction of the piezoelectric ceramic.

6. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The driving vibrators (4) are two groups of magnetostrictive vibrators that are symmetrical along the axial direction; Each group of magnetostrictive vibrators comprises: at least one magnetostrictive rod (7), two groups of permanent magnets (8) and an excitation coil (9); The magnetostrictive rods are horizontal to each other and are placed inside the underwater acoustic transducer along the axial direction. The top of the magnetostrictive rod is connected to the radiation head (1) through a permanent magnet (8), and the bottom of the magnetostrictive rod is connected to the central base (5) through a permanent magnet (8). The excitation coil (9) is coaxially wound around the magnetostrictive rod (7).

7. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The underwater acoustic transducer achieves transmission responses in both low-frequency and high-frequency bands through a single structure, thus being adaptable to different usage scenarios.

8. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1 is characterized in that: The dual-band transmission response of the underwater acoustic transducer is a single resonance peak plus a broadband, or a single resonance peak plus two broadbands.

9. The longitudinal vibration multi-mode coupled dual-band underwater acoustic transducer according to claim 1, characterized in that: The underwater acoustic transducer transmits a response of a single resonance peak plus a broadband, or two single resonance peaks plus a broadband.

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