Double-layer elastomer composite underwater sound absorption structure with inner-embedded sleeve structure and design method thereof

Abstract

The application belongs to the field of underwater sound absorption structure design, and relates to a double-layer elastomer composite underwater sound absorption structure with an embedded sleeve structure and a design method thereof. The structure comprises a plurality of periodically spliced structure units. The structure unit is in a regular hexagonal prism configuration. The structure unit comprises a rigid embedded support part and an elastomer sound absorption composite part. The rigid embedded support part comprises a rigid outer frame and a rigid sleeve embedded in the elastomer sound absorption composite part. The elastomer sound absorption composite part comprises two layers of rubber material layers arranged in an up-down mode and different in type. The Young's modulus of the upper rubber material layer is greater than that of the lower rubber material layer. The inner diameter and thickness of the rigid sleeve, the thickness of the rigid outer frame, and the thickness of the upper rubber material layer or the lower rubber material layer are optimized and designed through a simulated annealing algorithm. Compared with the prior art, the application has good compression resistance and low-frequency broadband sound absorption performance, and can realize efficient low-frequency broadband sound absorption under a certain hydrostatic pressure.

Description

Technical Field

[0001] This invention relates to the field of underwater sound-absorbing structure design, and in particular to a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure and its design method. Background Technology

[0002] In recent years, with the advancement of marine resource development technologies, the operating depth and complexity of underwater equipment have been continuously increasing. Rapid advancements in manufacturing processes have enabled submarine hulls to withstand greater external water pressure, allowing them to dive into deeper waters. However, increased water depth leads to a significant increase in hydrostatic pressure. Under high pressure, the microstructure of traditional stealth coatings undergoes significant deformation: the movement of polymer matrix molecular chains is hindered, free volume decreases, and damage occurs at the interface between the filler and the matrix. The dynamic mechanical parameters of the coating, such as storage modulus and loss factor, drift, and the glass transition temperature increases, resulting in frequency shifts and attenuation of the sound absorption peak. This change significantly reduces the coating's sound absorption efficiency, making it difficult to maintain the original broadband stealth performance, enhancing the acoustic characteristics of the equipment, and making it easier to detect. Therefore, developing novel stealth coatings with pressure-resistant mechanisms has become a crucial issue urgently needing breakthroughs in the field of deep-sea technology.

[0003] Meanwhile, sonar detection technology continues to upgrade, significantly enhancing its ability to identify and distinguish underwater targets. New sonar systems have made substantial progress in low-frequency broadband, multi-beamforming, synthetic aperture processing, and AI-assisted target recognition, enabling the extraction of weak echo characteristics from complex marine environmental noise. This advancement helps achieve more accurate detection and obstacle avoidance in complex deep-sea terrain, providing crucial protection for navigation safety. On the other hand, the increasing accuracy of identification also means that underwater equipment is finding it more difficult to remain invisible to sonar – even slight differences in acoustic characteristics or echo distortion caused by localized coating failures can be detected and classified by the new generation of sonar systems. This poses a more severe challenge to the stealth performance of equipment, forcing stealth technology to develop towards lower detectability, wider bandwidth adaptability, and active countermeasures.

[0004] The aforementioned two development trends jointly indicate that traditional underwater stealth solutions are no longer sufficient to meet the practical requirements for achieving low-frequency broadband sound absorption under high-pressure environments. Existing patent application CN120690163A discloses an underwater sound absorber and its design method that combine low-frequency broadband sound absorption and high pressure resistance. The sound absorber includes multiple sequentially assembled hexagonal honeycomb units. Each honeycomb unit consists of a hexagonal metal honeycomb skeleton, a rubber coating, an irregularly shaped embedded neck, and a cavity. The hexagonal honeycomb skeleton forms a hexagonal cylindrical cavity. The rubber coating is applied to the sidewalls and bottom plate of the honeycomb skeleton, and its acoustic impedance matches the underwater acoustic impedance, effectively absorbing sound wave energy. The irregularly shaped embedded neck is embedded in the honeycomb skeleton cavity, and the neck structure protrudes inward, significantly enhancing the sound wave velocity and thermal viscous loss. The cavity, formed by the honeycomb skeleton and rubber coating, is used to store sound energy and provide resonance space. However, this underwater sound absorber uses a cavity-type sound absorption structure, which is more prone to deformation in high-pressure environments, leading to a decrease in sound absorption performance. In addition, the structure is relatively complex and the manufacturing cost is high, which cannot meet the needs of today's deep-water operation environment. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure and its design method. The designed structure has good compressive strength and low-frequency broadband sound absorption performance, and can achieve efficient low-frequency broadband sound absorption under certain hydrostatic pressure, meeting the current harsh deep-water operating environment.

[0006] The objective of this invention can be achieved through the following technical solutions: A double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure includes multiple periodically spliced ​​structural unit cells. Each structural unit cell has a regular hexagonal prism configuration and includes a rigid nested support part and an elastomer sound-absorbing composite part. The rigid nested support part includes a rigid outer frame and a rigid sleeve embedded inside the elastomer sound-absorbing composite part. The elastomer sound-absorbing composite part includes two layers of different types of rubber materials arranged vertically, with the Young's modulus of the upper rubber material layer being greater than that of the lower rubber material layer.

[0007] Furthermore, the rigid sleeve divides the elastomeric sound-absorbing composite into an inner sound-absorbing part and an outer sound-absorbing part, both of which include two layers of different types of rubber material arranged vertically.

[0008] Furthermore, the thickness of the upper rubber material layer of the inner sound-absorbing part and the outer sound-absorbing part is different.

[0009] Furthermore, the structural parameters of the double-layer elastomer composite underwater sound-absorbing structure are optimized using a simulated annealing algorithm.

[0010] Furthermore, the structural parameters include the inner diameter and thickness of the rigid sleeve, the thickness of the rigid outer frame, and the thickness of the upper or lower rubber material layer.

[0011] Furthermore, the upper rubber material layer is made of polyurethane, and the lower rubber material layer is made of TPU.

[0012] Furthermore, the rigid nested support is made of steel.

[0013] The present invention also provides an optimized design method for the double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure as described above, comprising the following steps: Obtain the structural design requirements parameters and the structural parameters that need to be optimized. Based on the structural design requirements, an initial solution for the structural parameters is generated. The optimization objective is to maximize the average sound absorption coefficient of the structure within a set frequency range. The simulated annealing algorithm is used to find the optimal solution and obtain the global optimal solution that satisfies all geometric and physical constraints, thus completing the optimization design.

[0014] Furthermore, the structural design requirements parameters include the total height and radius of the structural unit cell.

[0015] Furthermore, the structural parameters include the inner diameter and thickness of the rigid sleeve, the thickness of the rigid outer frame, and the thickness of the upper or lower rubber material layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The structural unit cell of the present invention includes a rigid nested support and an elastomer sound-absorbing composite. The rigid nested support includes a rigid outer frame and a rigid sleeve embedded inside the elastomer sound-absorbing composite, which is used to resist hydrostatic pressure, reduce the deformation of the overall structure, and maintain the sound absorption performance of the structure under high pressure. The elastomer sound-absorbing composite includes two layers of different types of rubber materials arranged on the upper and lower sides. The rubber materials have a high attenuation coefficient and undertake the main sound absorption function, exhibiting gradient impedance characteristics. The upper rubber material is made of a material with a large Young's modulus, and its acoustic impedance is closer to that of water, which can reduce the scattering behavior of sound waves at the interface and ensure that sound waves are projected into the elastomer as much as possible. The lower rubber material is made of a material with a small Young's modulus. When sound waves enter this layer, they interact with the rubber layer, causing the rubber layer to deform significantly, converting the sound energy carried by the sound waves into heat energy, and achieving effective sound energy loss. This invention achieves broadband low-frequency sound absorption underwater with excellent sound absorption performance. The average sound absorption coefficient is 0.9458 in the 1000 Hz - 10000 Hz range, a significant improvement compared to the existing technology's average sound absorption coefficient of 0.9162. It offers a wide sound absorption range and highly efficient sound absorption effect. The sound absorption coefficient reaches over 0.8 around 1200 Hz, achieving low-frequency sound absorption.

[0017] 2. This invention has good compressive strength. By embedding a rigid sleeve structure in the matrix sound-absorbing material, the overall rigidity of the structure is effectively improved, ensuring that it maintains its structure under high water pressure and maintains efficient underwater sound absorption performance.

[0018] 3. This invention employs a combined structure of a rigid nested support and an elastomer sound-absorbing composite, resulting in a compact structure that achieves good sound absorption with a relatively small size. Tests have shown that this invention can achieve dimensions of 59mm radius and 45mm height or less. Attached Figure Description

[0019] Figure 1 This is an overall schematic diagram of a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure designed in an embodiment of the present invention; Figure 2 yes Figure 1 Schematic diagram of the structural unit cell of the medium structure; Figure 3 yes Figure 1 A partial cross-sectional diagram of the middle structure; Figure 4 Based on Figure 3 The established three-dimensional axisymmetric element model; Figure 5 This is a sound absorption coefficient curve of a double-layer elastomer composite underwater sound absorption structure with an inner nested cylinder structure designed in an embodiment of the present invention, with a frequency range of 50Hz-10000Hz. Figure 6 These are comparative curves of the sound absorption coefficients of underwater sound-absorbing structures when they are made of pure rubber, have an external rigid frame structure, or have an internal rigid sleeve structure. Figure 7 The sound absorption coefficient comparison curves of the underwater sound-absorbing structure with an inner-nested cylinder structure are shown when it contains only the first rubber layer, only the second rubber layer, and both layers of composite rubber. Figure 8 This is a schematic diagram of the design variables involved in the simulation degradation algorithm optimization of a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure designed in an embodiment of the present invention. Figure 9 This is a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure designed in this embodiment of the invention. The sound absorption coefficient comparison curves before and after optimization using the simulated annealing algorithm are shown. Figure 10 This is a comparison curve of the sound absorption coefficient of a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure designed in an embodiment of the present invention under different hydrostatic pressures. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0021] Example 1 This embodiment provides a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure. Figure 1 The overall configuration of the structure is shown, which is composed of periodically combined structural units of regular hexagonal prisms. The regular hexagonal prisms are easy to interlock and splice, and can be flexibly configured to form different shapes and sizes to meet the deployment needs of various submarine hull surfaces.

[0022] Figure 2 and Figure 3 The diagrams show a structural unit cell and a partial cross-sectional view of the structure. The structural unit cell includes a rigid nested support section and an elastomeric sound-absorbing composite section. The rigid nested support section comprises a rigid outer frame 3 and a rigid sleeve 4 embedded inside the elastomeric sound-absorbing composite section. The elastomeric sound-absorbing composite section consists of two layers of different types of rubber material, designated as a first rubber layer 1 and a second rubber layer 2. The Young's modulus of the upper rubber material layer is greater than that of the lower rubber material layer. The structural unit cell has two layers of rigid support from the outside in, providing the necessary strength and stiffness to resist hydrostatic pressure, reduce overall structural deformation, and maintain the structure's sound absorption performance under high pressure. The internally embedded rigid sleeve divides the elastomeric sound-absorbing composite section into inner and outer parts. Each part of the rubber is composed of two layers of different types of rubber. The rubber material has a high attenuation coefficient, undertaking the main sound absorption function, and exhibits gradient impedance characteristics, ensuring that sound waves are projected into the elastomer, achieving effective sound energy dissipation.

[0023] To improve simulation and optimization efficiency, the unit cell model has been reasonably simplified in this embodiment. Figure 4 Based on Figure 3 A three-dimensional cylindrical axisymmetric unit model was established. Analysis shows that, under appropriate structural parameters, the acoustic performance of the regular hexagonal prism unit cell structure can be equivalently approximated as a cylindrical axisymmetric structure. Based on this approximation, the three-dimensional model can be further simplified into a corresponding two-dimensional axisymmetric model, thereby significantly reducing the amount of numerical computation and greatly accelerating the optimization design process of the overall structure.

[0024] Specifically, in the aforementioned structural unit cell, the outer side of the nested cylinder structure is a rigid outer frame, while the inner side contains an embedded rigid sleeve. On one hand, the two rigid layers provide support, effectively reducing deformation under high pressure and maintaining excellent sound absorption performance. On the other hand, the two rigid layers resonate during sound absorption, improving the overall sound absorption performance to some extent. In the elastomer structure, the upper and lower layers are composited using different types of rubber materials. This utilizes the deformation of the rubber to dissipate sound energy, achieving effective sound absorption, and further enhances sound absorption performance through an acoustic impedance gradient. Specifically, the upper rubber material uses a material with a high Young's modulus, whose acoustic impedance is closer to that of water, reducing sound wave scattering at the interface and ensuring that sound waves are projected into the elastomer as much as possible. The lower rubber material uses a material with a low Young's modulus; when sound waves enter this layer, they interact with it, causing significant deformation and converting the sound energy carried by the sound waves into heat energy, achieving effective sound energy dissipation.

[0025] In this embodiment, the relevant geometric parameters of the three-dimensional cylindrical axisymmetric element model are as follows: total height h = 45mm, radius r = 59 mm. The geometric parameters of the inner and outer rigid support structures, as well as the thickness of each rubber layer, need to be determined after optimization design using a simulation degradation algorithm.

[0026] In this embodiment, the rigid support structure is made of steel, with the following material properties: density of 7850 kg / m³, Young's modulus of 200 GPa, and Poisson's ratio of 0.3. The elastomer is composed of two types of rubber. The lower layer is polyurethane (hereinafter referred to as the first rubber), with the following material properties: density of 1090 kg / m³, Young's modulus of 8 MPa, and Poisson's ratio of 0.46, and a decay coefficient of 0.3. The upper layer is TPU (hereinafter referred to as the second rubber), with the following material properties: density of 1100 kg / m³, Young's modulus of 75 MPa, and Poisson's ratio of 0.46, and a decay coefficient of 0.4.

[0027] Furthermore, based on Figure 4 Based on the cylindrical approximate unit cell structure of this feature, a corresponding two-dimensional axisymmetric finite element model was established. Simulation calculations were performed on the model to determine its sound absorption coefficient. The environmental material of the fluid layer in the model was set to water with a density of 1000 kg / m³. 3 The sound velocity is 1500 m / s. The sound absorption coefficient of the structure is obtained by simulation calculation, and its sound absorption curve is plotted.

[0028] like Figure 5As shown, the curve represents the sound absorption coefficient of the low-frequency broadband sound-absorbing structure based on a multi-layer nested structure in this embodiment within the range of 50Hz to 10000Hz. The structure achieves an average sound absorption coefficient of 0.9458 within the range of 1000Hz to 10000Hz, and the sound absorption coefficient after 1200Hz is higher than 0.8, effectively achieving the low-frequency broadband sound absorption target.

[0029] This embodiment studies the impact of a double-layer elastomer composite underwater sound-absorbing structure with an inner-nested cylinder structure on sound absorption performance. By comparing the sound absorption coefficients of different structural configurations in the frequency range of 50 Hz - 10000 Hz, the improvement effect of different structural configurations on sound absorption is analyzed and evaluated.

[0030] like Figure 6 As shown, the square-marked curve represents the sound absorption coefficient of the pure rubber structure in the range of 50 Hz - 10000 Hz; the circular-marked curve represents the sound absorption coefficient of the structure including the outer frame in the same range; and the triangular-marked curve represents the sound absorption coefficient of the structure including both the outer frame and the inner sleeve support in the same range. Analysis and comparison show that adding an outer frame support structure to the existing rubber as the sound-absorbing material improves the overall sound absorption performance of the structure. Furthermore, embedding an inner sleeve support further enhances the sound absorption performance.

[0031] like Figure 7 As shown, the circular curve represents the sound absorption coefficient of the structure in the 50 Hz - 10000 Hz range when the matrix is ​​only the first rubber; the triangular curve represents the sound absorption coefficient of the structure in the 50 Hz - 10000 Hz range when the matrix is ​​only the second rubber; and the square curve represents the sound absorption coefficient of the structure in the 50 Hz - 10000 Hz range when the matrix is ​​composed of two layers of rubber. Analysis and comparison show that when the second rubber, with its higher Young's modulus, is used as the matrix sound-absorbing material, the overall sound absorption performance of the structure is better than that of the structure using the first rubber. Furthermore, by combining the first and second rubbers, the sound absorption coefficient of the structure is further improved.

[0032] Specifically, the Young's modulus of the first and second rubbers differs significantly. The Young's modulus of a rubber material affects its sound absorption performance in two ways: firstly, increasing the Young's modulus effectively increases the acoustic impedance of the matrix, narrowing the difference between it and water, thus allowing more sound waves to penetrate the sound-absorbing structure and be absorbed. Secondly, for rubber materials with a smaller Young's modulus, sound waves propagating internally are more likely to cause material deformation, resulting in energy loss as heat. In this embodiment, the Young's modulus of the second rubber is required to be as large as possible to increase the acoustic impedance, making it close to that of water and reducing sound wave scattering. The selection of the Young's modulus of the first rubber needs to ensure that sound waves are sufficiently attenuated during propagation.

[0033] Based on this, a first rubber and a second rubber composite are used to create an upper and lower acoustic impedance gradient for the matrix sound-absorbing layer. On the one hand, the acoustic impedance of the upper second rubber is closer to that of water, which can increase the proportion of sound waves projected into the sound-absorbing structure. On the other hand, the first rubber has a small Young's modulus, which can ensure that the sound waves entering the sound-absorbing structure are more likely to cause deformation of the rubber material, so that the sound energy is fully dissipated in the sound-absorbing structure.

[0034] In other embodiments, the first rubber may also be made of other conventional rubber materials such as epoxy resin, chlorinated polyethylene rubber, or TPU.

[0035] Example 2 Building upon Example 1, to obtain optimal structural geometric parameters and achieve the best sound absorption performance, an intelligent optimization algorithm is needed to optimize the structural design. Therefore, this example employs a simulated annealing algorithm for structural optimization, including the following steps: obtaining structural design requirement parameters and the structural parameters to be optimized. The structural design requirement parameters include the total height and radius of the structural unit cell, and the structural parameters include the inner diameter and thickness of the rigid sleeve, the thickness of the rigid outer frame, and the thickness of the upper or lower rubber material layer. Based on the structural design requirement parameters, an initial solution for the structural parameters is generated. An optimization objective is established to maximize the average sound absorption coefficient within a set frequency range. The simulated annealing algorithm is then used to find the optimal solution that satisfies all geometric and physical constraints, thus completing the optimization design. The optimized sound-absorbing structure exhibits significantly improved sound absorption performance within the target frequency band, effectively enhancing the low-frequency broadband sound absorption effect.

[0036] Simulated annealing is a commonly used intelligent optimization method inspired by the physical phenomena observed during solid-state annealing. This algorithm can perform a global search while also considering detailed optimization in local regions, effectively avoiding getting trapped in local optima. It is suitable for handling optimization problems with complex constraints. Specifically, the basic process of this algorithm in this embodiment can be summarized as follows: (1) Generating a perturbation solution based on the step size. The algorithm generates a perturbation solution based on the current solution and the current temperature, according to a certain step size. In this embodiment, a dynamic step size strategy is adopted, which dynamically adjusts and updates the step size according to the ratio of the current temperature to the initial temperature. Specifically, when the temperature is high, the step size is larger, which is conducive to global exploration and reduces the probability of getting trapped in a local optimum; as the temperature decreases, the step size also decreases, and the algorithm will perform local fine-grained search.

[0037] Once the perturbation solution is generated, it needs to be verified whether it meets the constraints. If not, one of three repair strategies is dynamically selected based on the current temperature: First, direct scaling, which pulls variables that exceed the boundary back into the feasible region proportionally; second, reflection processing, which mimics the principle of light reflection to symmetrically bounce solutions that do not meet the constraints back into the feasible region, thereby maintaining the diversity of solutions; and third, re-random generation, which directly obtains feasible solutions through multiple random attempts at high temperatures to enhance the randomness of the search.

[0038] The algorithm adopts a dynamic step size strategy and a dynamic repair strategy in the step of generating new solutions. The iteration step size and repair strategy are reasonably selected according to the current temperature. The three repair strategies correspond to the three stages of temperature reduction: regeneration at high temperature, reflection processing at medium temperature, and direct scaling at low temperature. This is conducive to global exploration and local fine-grained search, and improves the search accuracy. (2) Calculate the objective function value and determine whether to accept the perturbation solution. After generating the perturbation solution, it is necessary to calculate the objective function value of the perturbation solution and compare it with the optimal solution to determine whether to accept the perturbation solution. If the perturbation solution is better, it is directly accepted as the new current solution. If the perturbation solution is worse than the current solution, it is accepted with a certain probability according to the Metropolis criterion. The acceptance probability formula is: in For the function value increment, This is the current temperature.

[0039] During algorithm execution, the optimal solution and corresponding objective function value for each iteration are recorded. Furthermore, the temperature value is gradually decreased, and the algorithm's search accuracy gradually increases, ensuring both precision and minimizing the risk of getting trapped in local optima. When the temperature drops to a certain value, or the number of iterations reaches a set maximum, the optimization process stops, and the algorithm outputs the final optimal solution and corresponding objective function value.

[0040] Figure 8 To optimize the mapping between design variables and the geometric parameters of the structure in the design process. Specifically, n 1 and n 2 represents the inner diameter and thickness of the inner sleeve structure, respectively. n 3 represents the thickness of the outer frame structure. n 4 andn 5 represents the thickness of the second rubber in the inner and outer composite rubber bodies, respectively. The objective function is the average sound absorption coefficient of the structure in the frequency range of 1010 Hz - 10000 Hz. The final design goal is to maximize the objective function, i.e., the average sound absorption coefficient of the structure.

[0041] The constraints in the optimization problem designed in this embodiment are: (1) Design variables n 1. n 2. n 3. n 4. n All 5 are greater than 0, that is: n i > 0 ( i = 1, 2, 3, 4, 5) (2) n 1. n 2. n The sum of 3 must be less than the overall thickness of the structure, that is: n 1 + n 2 + n 3 < 59 mm (3) n 4 and n 5 needs to be less than the overall height of the structure, that is: n 4 < 45 mm n 5 < 45 mm The optimized parameters are shown in Table 1.

[0042] Table 1 like Figure 9 As shown, the solid square markings represent the sound absorption coefficient of the low-frequency broadband sound-absorbing structure based on a multi-layer nested structure in the range of 50 Hz to 10000 Hz before optimization using the simulated annealing algorithm. The dashed square markings represent the sound absorption coefficient of the structure in the range of 50 Hz to 10000 Hz after optimization using the algorithm. After optimization, the sound absorption performance of the structure is significantly improved, and the sound absorption coefficient is more stable.

[0043] To evaluate the compressive strength of the designed double-layer elastomer composite underwater sound-absorbing structure with an inner-nested cylinder structure, it is necessary to study the effect of different hydrostatic pressures on its sound absorption coefficient, thereby verifying whether the structure has sufficient pressure resistance to ensure that it can maintain stable sound absorption performance under high pressure.

[0044] The following is a simulation calculation process for the sound absorption coefficient of a structure under hydrostatic pressure. This process mainly consists of two steps: The first step is mechanical analysis, which involves establishing a separate solid domain model and applying hydrostatic pressure as a boundary load to the acoustic-structure interaction surface, calculating the resulting structural deformation. The second step is acoustic simulation, which involves importing the deformed model, supplementing it with a water area model to complete the acoustic modeling, and then performing acoustic simulation calculations to obtain the sound absorption coefficient of the structure under hydrostatic pressure.

[0045] like Figure 10 As shown, the square-marked curve represents the sound absorption coefficient of the multi-layered nested structure at a hydrostatic pressure of 0.1 MPa; the circular-marked curve represents the sound absorption coefficient of the multi-layered nested structure at a hydrostatic pressure of 1 MPa; and the triangular-marked curve represents the sound absorption coefficient of the multi-layered nested structure at a hydrostatic pressure of 3 MPa. Comparative analysis shows that the sound absorption coefficient curves of this structure at hydrostatic pressures of 0.1 MPa, 1 MPa, and 3 MPa are basically identical, indicating that the structure has excellent compressive strength and can effectively ensure that it maintains excellent sound absorption performance under high hydrostatic pressure.

[0046] In other implementations, optimization algorithms such as genetic algorithms, particle swarm optimization, and ant colony optimization can be used to replace the simulated annealing algorithm described above.

[0047] This invention designs a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure, and optimizes the geometric parameters of the structure using a simulated annealing algorithm. The designed structure exhibits good sound absorption performance in the 50 Hz - 10000 Hz range and has a certain degree of pressure resistance, effectively meeting the requirements for efficient low-frequency broadband sound absorption under high-pressure environments and coping with more demanding underwater operating environments.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A double-layer elastomer composite underwater sound-absorbing structure with an inner nested tube structure, comprising multiple periodically spliced ​​structural unit cells, wherein the structural unit cells are in a regular hexagonal prism configuration, characterized in that, The structural unit cell includes a rigid nested support and an elastomeric sound-absorbing composite. The rigid nested support includes a rigid outer frame and a rigid sleeve embedded inside the elastomeric sound-absorbing composite. The elastomeric sound-absorbing composite includes two layers of different types of rubber material arranged on the upper and lower sides. The Young's modulus of the upper rubber material layer is greater than that of the lower rubber material layer.

2. The double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure according to claim 1, characterized in that, The rigid sleeve divides the elastomeric sound-absorbing composite into an inner sound-absorbing part and an outer sound-absorbing part, both of which include two layers of different types of rubber material arranged vertically.

3. The double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure according to claim 2, characterized in that, The thickness of the upper rubber material layer of the inner and outer sound-absorbing parts is different.

4. The double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure according to claim 1, characterized in that, The structural parameters of the double-layer elastomer composite underwater sound-absorbing structure were optimized using a simulated annealing algorithm.

5. The double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure according to claim 4, characterized in that, The structural parameters include the inner diameter and thickness of the rigid sleeve, the thickness of the rigid outer frame, and the thickness of the upper or lower rubber material layer.

6. The double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure according to claim 1, characterized in that, The upper rubber material layer is made of polyurethane, and the lower rubber material layer is made of TPU.

7. The double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure according to claim 1, characterized in that, The rigid nested support is made of steel.

8. An optimized design method for a double-layer elastomer composite underwater sound-absorbing structure with an inner nested cylinder structure as described in any one of claims 1-7, characterized in that, Includes the following steps: Obtain the structural design requirements parameters and the structural parameters that need to be optimized. Based on the structural design requirements, an initial solution for the structural parameters is generated. The optimization objective is to maximize the average sound absorption coefficient of the structure within a set frequency range. The simulated annealing algorithm is used to find the optimal solution and obtain the global optimal solution that satisfies all geometric and physical constraints, thus completing the optimization design.

9. The optimization design method according to claim 8, characterized in that, The structural design requirements parameters include the total height and radius of the structural unit cell.

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