Broadband omnidirectional high-target-intensity acoustic marker based on multi-layer composite board corner reflector

Abstract

The invention provides a broadband omnidirectional high-target-intensity acoustic marker based on a multi-layer composite board corner reflector. The broadband omnidirectional high-target-intensity acoustic marker comprises a supporting frame and a plurality of acoustic trihedral corner reflector units, the supporting frame is in a circular ring shape, and the acoustic three-face corner reflector units are evenly fixed to the supporting frame. Each acoustic trihedral corner reflector unit is of a trihedral structure formed by connecting three isosceles right triangle multilayer composite plates with the same size in a pairwise perpendicular mode, and the trihedral structure is provided with three reflection planes perpendicular to one another. And the acoustic trihedral corner reflector units are circumferentially, uniformly and fixedly mounted on the supporting frame by taking the vertexes of the acoustic trihedral corner reflector units as reference, so that the opening directions of all the acoustic trihedral corner reflector units face the radial outer side of the acoustic marker body. According to the invention, the target strength of the corner reflector is enhanced and the structure is designed to be lightweight by adopting multiple layers of composite plates made of different materials, and the target strength in a wide-band and wide-angle range is enhanced by combining a plurality of corner reflector units.

Description

Technical Field

[0001] This invention relates to the field of underwater target acoustic marker technology, specifically to a broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector. Background Technology

[0002] Currently, underwater acoustic beacons mainly operate using active sonar that emits single-frequency ultrasonic pulse signals. This method suffers from drawbacks such as high cost, high power consumption, narrow bandwidth, low communication speed, short operating time, and susceptibility to exposure. In recent years, the concept of passive underwater acoustic markers has been proposed and gradually researched and developed. These markers utilize the acoustic scattering characteristics of targets; the detected target only responds when questioned. They do not require a portable power source or accompanying equipment, and offer advantages such as low cost, long service life, and ease of deployment.

[0003] Passive acoustic markers in underwater environments need to possess characteristics such as small size, high target intensity, and good consistency between target intensity frequency and spatial orientation. Commonly used passive acoustic marker structures include spherical, cylindrical, and corner reflector types. While spherical structures offer the advantage of omnidirectional target intensity in space, achieving high target intensity requires a large sphere as the frequency decreases, which is inconvenient for experimental deployment and transportation. Cylindrical structures only exhibit high acoustic target intensity when the sound wave is perpendicularly incident, and the target intensity varies drastically with the incident angle. Corner reflector structures enhance the target echo through multiple scattering interferences of sound waves between different surfaces, and strong target echoes over a wide range can be achieved through different structural designs. Common underwater corner reflectors consist of mutually perpendicular steel plates; to achieve minimal sound wave transmission, the steel plate thickness is large, resulting in a large overall structural weight; and a single corner reflector only produces a strong echo in a specific direction.

[0004] Patent application CN108631064A discloses a dual-band corner reflector and its design method, comprising: three metal plates and a frequency selective surface dielectric plate; any two of the three metal plates are arranged perpendicularly to each other to form a semi-elliptical recessed structure, wherein the two perpendicular metal plates share a common connecting edge, and the length of the common connecting edge is equal; the frequency selective surface dielectric plate is connected to each of the three metal plates. However, this patent cannot completely solve the existing technical problems, nor can it meet the needs of this invention. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a broadband omnidirectional high-intensity acoustic marker based on a multilayer composite plate corner reflector.

[0006] The broadband omnidirectional high-target-intensity acoustic marker based on a multi-layer composite plate corner reflector provided by the present invention includes: a support frame and multiple acoustic trihedral corner reflector units; The support frame is in the form of a ring, and multiple acoustic trihedral reflector units are evenly fixed on the support frame. Each acoustic trihedral reflector unit consists of three isosceles right-angled triangular multilayer composite plates of the same size connected perpendicularly to each other in pairs to form a trihedral structure, which has three mutually perpendicular reflective planes; The acoustic trihedral reflector units are fixedly mounted circumferentially and uniformly on the support frame with their apex as a reference, so that the opening direction of all acoustic trihedral reflector units faces the radial outer side of the acoustic marker.

[0007] Preferably, the isosceles right-angled triangular multilayer composite board is made of multiple layers of boards of different materials and thicknesses, and sound reflection is achieved by impedance matching between boards of different materials.

[0008] Preferably, the multilayer composite panel includes an outer steel plate, a middle polyurethane plate, and an inner steel plate, wherein the outer and inner steel plates are made of stainless steel, and the middle layer is made of polyurethane.

[0009] Preferably, the inner steel plate has a thickness of 2 mm, the middle polyurethane plate has a thickness of 10 mm, and the outer steel plate has a thickness of 4 mm.

[0010] Preferably, the reflectance coefficient of the acoustic marker is calculated using the following formula:

[0011] in, , , , ; Indicates the acoustic impedance of the incident medium; Indicates the acoustic impedance of the exiting medium; , , , These are elements in the overall transfer matrix F; , , This demonstrates the effect of medium thickness on sound wave propagation. This demonstrates the influence of the interface on sound wave propagation. and These are the transfer matrix and thickness of the nth layer material, respectively.

[0012] Preferably, the overall transfer matrix F is calculated using the transfer matrix of the multilayer board, wherein each transfer matrix... With the thickness of the nth layer material Related to acoustic properties, it is used to describe the propagation behavior of sound waves in multilayer composite panels.

[0013] Preferably, the length of the right-angled side of the isosceles right-angled triangular multilayer composite plate of the acoustic trihedral reflector unit is 0.4m, and the target intensity of the reflector unit can be changed by adjusting the length of the right-angled side and the thickness of the multilayer plate.

[0014] Preferably, the number of acoustic trihedral reflector units is six, which are evenly distributed circumferentially on the annular support frame to enhance the target intensity over a wider angle range.

[0015] Preferably, the circular support frame is made of a composite material with low density, high strength and good acoustic transmittance to avoid interference with sound wave reflection; and the support frame is provided with hanging rings for easy deployment and retrieval.

[0016] Preferably, the stainless steel material of the steel plate has a density of 7800 kg / m³. Young's modulus is 2.1 × Pa, Poisson's ratio is 0.3; the density of the polyurethane material is 500 kg / m³. Young's modulus is 1.45 × Pa, Poisson's ratio is 0.35.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector. It uses multi-layer composite plates of different materials to enhance the target intensity of the corner reflector and achieve a lightweight design. By combining multiple corner reflector units, it achieves target intensity enhancement over a wide range of angles. The marker has advantages such as strong concealment, simple structure, low cost, and high stability. The marker can be used for underwater target positioning, navigation, etc. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 Reflectance coefficient curves of steel plates and multi-layer composite panels incident at different angles in water; Figure 2 This is a structural diagram of a single trihedral corner reflector unit; Figure 3 A graph showing the target intensity calculation for a trihedral corner reflector element; Figure 4 This is a geometric diagram of the combined corner reflector; Figure 5 The image shows the simulation results of the target intensity from all directions for the combined corner reflector structure. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0020] Example This invention proposes a broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector. When sound waves are incident on the corner reflector, multiple scattering interferences occur, enhancing the echo intensity. The acoustic marker employs multiple composite plates of different materials, achieving enhanced target intensity while maintaining a lightweight structure. By combining multiple corner reflector units, broadband and wide-range target intensity enhancement is achieved, thus improving the angular consistency of target intensity. This invention's passive underwater acoustic marker offers advantages such as strong concealment, simple structure, low cost, and high stability.

[0021] The broadband omnidirectional target intensity acoustic marker based on multilayer composite plate corner reflectors of the present invention includes a ring-shaped support frame and multiple acoustic trihedral corner reflector units uniformly fixed thereon; The trihedral reflector unit consists of three isosceles right-angled triangular multilayer composite plates of the same size, connected perpendicularly to each other in pairs to form a trihedral structure. This structure has three mutually perpendicular reflective planes. The target intensity of the reflector unit can be changed by adjusting the length of the right-angled sides and the thickness of the multilayer plates.

[0022] The three-sided corner reflector unit is fixedly mounted circumferentially and uniformly on the circular support frame with its vertex as the reference, so that the opening direction of all units faces the radial outer side of the marker body.

[0023] The isosceles right-angled triangular multilayer composite plate is made of multiple layers of different materials and thicknesses. It achieves excellent acoustic reflection performance by utilizing the impedance mismatch between the different materials, and selects highly corrosion-resistant materials to ensure long-term underwater corrosion resistance. The target intensity of the reflector unit can be changed by altering the length of the right-angled sides, the different plate materials, and the plate thickness.

[0024] The circular support frame is made of a composite material with low density, high strength, and good acoustic transmittance to avoid unnecessary interference from the reflection of sound waves.

[0025] The support frame is equipped with hanging rings for suspension, which facilitates the placement and retrieval of the marker.

[0026] This invention utilizes wave propagation theory in layered media to obtain the reflection coefficient of sound waves incident on a multilayer board through the transfer matrix method. The formula for the reflection coefficient is as follows:

[0027] in, , , , ; Indicates the acoustic impedance of the incident medium; Indicates the acoustic impedance of the exiting medium; , , , These are elements in the overall transfer matrix F; , , This demonstrates the influence of medium thickness on sound wave propagation. This demonstrates the influence of the interface on sound wave propagation.

[0028] The reflection coefficients of 10kHz sound waves incident at different angles on steel plates and multi-layer composite panels in water were obtained using the above formula. Figure 1 As shown, 0° indicates that the sound wave is incident perpendicularly on the plate. The solid black line represents the reflection coefficient of the steel plate in water, and the dashed blue line represents the reflection coefficient of the steel-polyurethane-steel composite plate in water. The reflection coefficient of the steel plate is unstable and decreases rapidly with increasing sound wave incident angle; while the reflection coefficient of the composite plate is more stable with sound wave incident angle, close to 1. Therefore, this invention uses a multi-layer composite plate to form a three-sided corner reflector to enhance the target intensity.

[0029] The steel plate described in this invention has a thickness of 6mm, and the density of the stainless steel material is... =7800kg / m3, Young's modulus is E=2.1 1011 Pa, Poisson's ratio =0.3; The multi-layer composite board of the present invention is composed of an outer steel plate, a polyurethane plate, and an inner steel plate. The thickness of the inner steel plate is hp1=2mm, the thickness of the middle polyurethane plate is hp2=10mm, the thickness of the outer steel plate is hp3=4mm, and the density of the polyurethane material is... =500kg / m3, Young's modulus is E=1.45 108 Pa, Poisson's ratio =0.35.

[0030] The single trihedral corner reflector unit structure described in this invention is as follows: Figure 2 As shown, a triangular composite panel of three identical isosceles right triangles is connected perpendicularly to each other in pairs to form a trihedral structure. This structure has three mutually perpendicular reflecting planes. The target intensity of the reflector unit can be changed by adjusting the length of the right-angled sides and the thickness of the multilayer panels. The angle between the incident direction of the sound wave and the z-axis is... The angle between the incident direction of the sound wave and the x-axis is given.

[0031] The target strength of the trihedral corner reflector element described in this invention was numerically calculated using multiphysics coupling in the commercial finite element software Comsol Multiphysics. Specifically, the pressure acoustics module and the solid mechanics module were coupled. The right-angle side length of the trihedral corner reflector described in this invention is L = 0.4 m, the calculation frequency is 10 kHz, and the incident direction of the sound wave is... =90° =0-90°, the calculation result is as follows Figure 3 As shown.

[0032] The individual trihedral corner reflector unit has a strong echo only in a specific direction. By combining the corner reflector units, a larger range of target intensity enhancement can be achieved. The geometry of the combined corner reflector is as follows: Figure 4 As shown, it includes a ring-shaped support frame and six acoustic trihedral corner reflector units uniformly fixed thereon.

[0033] The six trihedral corner reflector units are circumferentially and uniformly fixed on the annular support frame with their vertices as reference, such that the opening direction of all units faces the radially outward of the marker body.

[0034] The simulation results of the omnidirectional target strength of the combined corner reflector structure are as follows: Figure 5 As shown, the target intensity of the 10kHz combined corner reflector structure and the direction of sound wave incidence. =90° =0-360°, and its target intensity value is mainly distributed between -9dB and -3dB. Compared with a rigid sphere of the same size, the target intensity is increased by 5.1dB. Therefore, the underwater passive acoustic marker based on multi-layer composite plate corner reflectors of this invention can not only achieve a lightweight structural design, but also enhance the target intensity over a wide angle range through the combination of corner reflector units.

[0035] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0036] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector, characterized in that, include: Support frame and multiple acoustic trihedral reflector units; The support frame is in the form of a ring, and multiple acoustic trihedral reflector units are evenly fixed on the support frame. Each acoustic trihedral reflector unit consists of three isosceles right-angled triangular multilayer composite plates of the same size connected perpendicularly to each other in pairs to form a trihedral structure, which has three mutually perpendicular reflective planes; The acoustic trihedral reflector units are fixedly mounted circumferentially and uniformly on the support frame with their apex as a reference, so that the opening direction of all acoustic trihedral reflector units faces the radial outer side of the acoustic marker.

2. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 1, characterized in that, The isosceles right-angled triangular multilayer composite board is made of multiple layers of boards of different materials and thicknesses, and sound reflection is achieved by using impedance matching between boards of different materials.

3. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 2, characterized in that, The multi-layer composite panel includes an outer steel plate, a middle polyurethane plate, and an inner steel plate, wherein the outer and inner steel plates are made of stainless steel, and the middle layer is made of polyurethane.

4. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 3, characterized in that, The inner steel plate has a thickness of 2mm, the middle polyurethane plate has a thickness of 10mm, and the outer steel plate has a thickness of 4mm.

5. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 1, characterized in that, The reflectance coefficient of the acoustic marker is calculated using the following formula: in, , , , ; Indicates the acoustic impedance of the incident medium; Indicates the acoustic impedance of the exiting medium; , , , These are elements in the overall transfer matrix F; , , This demonstrates the effect of medium thickness on sound wave propagation. This demonstrates the influence of the interface on sound wave propagation. and These are the transfer matrix and thickness of the nth layer material, respectively.

6. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 5, characterized in that, The overall transfer matrix F is calculated from the transfer matrix of the multilayer board, where each transfer matrix... With the thickness of the nth layer material Related to acoustic properties, it is used to describe the propagation behavior of sound waves in multilayer composite panels.

7. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 1, characterized in that, The isosceles right-angled triangular multilayer composite plate of the acoustic trihedral reflector unit has a right-angled side length of 0.4m. The target intensity of the reflector unit can be changed by adjusting the right-angled side length and the thickness of the multilayer plate.

8. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 1, characterized in that, The number of acoustic trihedral reflector units is six, which are evenly distributed circumferentially on the annular support frame to enhance the target intensity over a wider angle range.

9. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 1, characterized in that, The circular support frame is made of a composite material with low density, high strength and good acoustic transmittance to avoid interference with sound wave reflection; and the support frame is equipped with hanging rings for easy deployment and retrieval.

10. The broadband omnidirectional high-intensity acoustic marker based on a multi-layer composite plate corner reflector according to claim 3, characterized in that, The stainless steel material of the steel plate has a density of 7800 kg / m³. Young's modulus is 2.1 × Pa, Poisson's ratio is 0.3; the density of the polyurethane material is 500 kg / m³. Young's modulus is 1.45 × Pa, Poisson's ratio is 0.35.

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