A multi-layer porous plate structure for shock absorption of a very large floating body

Abstract

The present invention relates to the field of ocean engineering and discloses a multi-layer porous plate structure for damping of ultra-large floating bodies. This structure is composed of multiple horizontally arranged porous plates. The porous plates are rigidly connected to the floating body through fixing devices and are made of high-strength lightweight materials. Openings are evenly distributed on the surface of each porous plate. The porosity, plate spacing, water entry depth, and number of plate layers of the porous plates can be flexibly adjusted according to the working environment of the floating body and wave conditions. The porosity ranges from 6% to 15%, the plate spacing is 4.2% to 16.7% of the working water depth of the floating body, and the water entry depth is 1 to 3 times the wave height downward from the bottom surface of the floating body. Through reasonable design and arrangement, the multi-layer porous plates can effectively reduce the transmission and reflection of wave energy, enhance the energy dissipation capacity, and achieve vibration reduction on the wave-facing side and dynamic stability on the leeward side. The present invention has the characteristics of flexible structure design, remarkable vibration reduction effect, and wide application range, and is applicable to ultra-large floating body projects in offshore and deep sea areas.

Description

Technical Field

[0001] The present invention relates to the technical field of ocean engineering, and particularly to a multi-layer pore plate structure for damping of ultra-large floating structures. Background Art

[0002] As a new type of ocean structure, the ultra-large floating structure (VLFS) has received extensive attention in the field of ocean development in recent years due to its broad application prospects and engineering advantages. However, in actual operation, the hydroelastic response of VLFS under wave action and the maximum force on the mooring system are key technical problems. The existence of these problems not only affects the stability and durability of the floating structure, but also poses a severe challenge to the safety of the mooring system.

[0003] Existing damping methods mainly rely on the adjustment of the stiffness or mass of the floating body itself, and the mitigation of the impact of wave energy on the floating body by adding external damping devices. Among them, although the methods of stiffness and mass adjustment can improve the dynamic response of the floating body to a certain extent, they usually increase the design complexity and construction cost of the floating body, and it is difficult to adapt to complex wave conditions. External damping devices, such as breakwaters or floating energy dissipation structures, although effective, often require a large layout space and are limited in high wave energy environments.

[0004] Regarding the application of the pore plate structure, existing research has shown that single-layer or double-layer pore plates have certain damping capabilities, especially in reducing the hydroelastic response on the wave-facing side of the floating body by dissipating wave energy. However, the existing pore plate designs have limitations in structural performance. For example, single-layer designs are difficult to meet the damping requirements under multi-wavelength conditions, and the energy dissipation efficiency of double-layer designs is still not ideal in high wave energy environments. In addition, the optimization ranges of key parameters such as porosity, plate spacing, and water entry depth are not clear, resulting in insufficient guidance and adaptability in actual engineering. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a multi-layer pore plate structure for damping of ultra-large floating structures, which solves the problems of insufficient damping performance, low energy dissipation efficiency, and difficulty in adapting to complex wave conditions in the prior art of single-layer or double-layer pore plate structures.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A multi-layer pore plate structure for damping of ultra-large floating structures, comprising a plurality of horizontally arranged pore plates, the plurality of pore plates are connected to each other to form a multi-layer pore plate structure, each pore plate is made of a high-strength lightweight material, the surface of the pore plate is provided with uniformly distributed openings, and the multi-layer pore plate is connected to the ultra-large floating structure through a fixing device for reducing the hydroelastic response and the maximum mooring force of the floating body, wherein:

[0007] The porosity of the pore plate is 6% to 15%.

[0008] The number of pore plate layers is 2 to 4 layers.

[0009] The plate spacing between adjacent pore plates is 4.2% - 16.7% of the working water depth of the floating body.

[0010] The water entry depth of the pore plate is 1 to 3 times the wave height downward from the bottom surface of the floating body.

[0011] Preferably, the pore plate is made of a lightweight and high-strength material, including acrylic plate or polycarbonate plate.

[0012] Preferably, the horizontal position of the pore plate is adjustable. Specifically:

[0013] The distance between the front edge position of the pore plate on the wave-facing side and the front edge of the floating body model is 0.25 times to 1 time the length of the pore plate.

[0014] The rear edge position of the pore plate on the lee side can be adjusted in the wave-facing direction or the lee direction of the floating body according to the wavelength, and the adjustment range is 0.25 times to 1 time the length of the pore plate.

[0015] Preferably, the connection method between the pore plate and the floating body is a rigid connection or an elastic connection, and is fixed by bolts, installed with an adjustable slide rail or elastically supported to adapt to different wave frequencies and mooring methods.

[0016] Preferably, the multi-layer pore plate structure is installed on the wave-facing side of the floating body or on both the wave-facing side and the lee side. When installed on both sides, the porosity and the number of layers of the pore plate on the wave-facing side and the lee side can be adjusted separately to optimize the vibration damping effect on the wave-facing side and the lee side.

[0017] Preferably, elastic floating balls are arranged between adjacent pore plates on the wave-facing side or the lee side. The elastic floating balls are fixed between adjacent pore plates through a fishing net or a frame structure, and the material of the elastic floating balls is rubber with a density close to that of water.

[0018] Preferably, the multi-layer pore plate structure is applicable to a floating body system using a subsea anchor chain mooring method or a mooring post mooring method. Specifically:

[0019] In the case of the subsea anchor chain mooring method, a bilateral installation mode is adopted.

[0020] In the case of the mooring post mooring method, a single-sided installation mode on the wave-facing side is adopted.

[0021] Preferably, the multi-layer pore plate structure adjusts the wave reflection coefficient, transmission coefficient and energy dissipation coefficient of the floating body by changing the porosity, plate spacing, number of layers, horizontal position and water entry depth of the pore plate to adapt to different marine environments and wave conditions.

[0022] Preferably, under wave conditions where the ratio of the wavelength to the floating body length is less than 0.3, the multi-layered perforated plate structure can reduce the maximum values of the hydroelastic responses on the wave-facing side and the lee side of the floating body; under wave conditions where the ratio of the wavelength to the floating body length is greater than 0.3, the vibration damping effect is concentrated on the wave-facing side of the floating body.

[0023] The present invention provides a multi-layered perforated plate structure for damping vibration of a very large floating structure (VLFS). It has the following beneficial effects:

[0024] 1. By adopting the multi-layered perforated plate structure, the present invention significantly reduces the hydroelastic response of the very large floating structure (VLFS) under wave action, especially on the wave-facing side. Under medium and short wave conditions, the optimized porosity, plate spacing, and draft can effectively reduce the vibration amplitude of the floating body structure and improve the structural stability, thus meeting the strict requirements of ocean engineering against wave disturbances.

[0025] 2. By adjusting the geometric parameters and installation methods of the perforated plates (including single-sided or double-sided installation, multi-layer design, etc.), the present invention can reduce the maximum mooring force of the VLFS, especially showing a good reduction effect in the short wave range. This performance optimization helps to extend the service life of the mooring system, reduce its force peak value, and improve the safety and reliability of the system.

[0026] 3. Through the porous design and layer number optimization of the perforated plate structure, the dissipation effect of wave energy is significantly enhanced. When the wave passes through the perforated plate, the fluid flows in the pores, generating frictional resistance and vortex dissipation. The combined action of the two effectively reduces the transmitted energy of the wave and improves the overall vibration damping effect, thereby achieving the control of the flow field around the VLFS.

[0027] 4. By reasonably designing the parameters of the perforated plate (such as porosity, plate spacing, draft, etc.), the present invention can exhibit excellent performance in different wavelength ranges (short wave, medium wave, and long wave), especially achieving the best vibration damping effect in the medium wave range, with good environmental adaptability and wide engineering applicability.

[0028] 5. The multi-layered perforated plate structure allows for the adjustment of the number of layers, plate spacing, and porosity to meet different engineering requirements. This modular design is convenient for flexible configuration during engineering implementation, adapting to different floating body structures, wave conditions, and vibration damping goals, while reducing the manufacturing and installation difficulties. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the structural diagram of the multi-layered perforated plate of the present invention;

[0030] Figure 2 is the schematic diagram of the perforated plate of the present invention;

[0031] Figure 3Schematic diagram of the U-shaped connector of the present invention;

[0032] Figure 4 Schematic diagram of the installation position of the fixing device of the present invention;

[0033] Figure 5 Schematic diagram of filling elastic floating balls into the multi-layer pore plate of the present invention;

[0034] Figure 6 Schematic diagram of the material composition of the VLFS model of the present invention;

[0035] Figure 7 Schematic diagram of the arrangement of the VLFS model in water of the present invention;

[0036] Figure 8 Schematic diagram of the mooring method of the present invention. Specific embodiments

[0037] Next, in conjunction with the accompanying drawings of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0038] Please refer to the appendix Figure 1 - appendix Figure 8 , the present invention provides a multi-layer pore plate structure for the vibration reduction of super-large floating bodies, aiming to solve the problems of insufficient vibration reduction effect, poor adaptability and limited optimization of mooring force of single-layer or double-layer pore plates in the prior art for super-large floating body structures (VLFS). By optimizing the structural parameters and arrangement methods of the multi-layer pore plate, the hydroelastic response and maximum mooring force of the floating body under regular waves and irregular waves can be significantly reduced, and the stability and safety of the super-large floating body structure can be improved.

[0039] The multi-layer pore plate of the present invention is proposed based on three-dimensional physical model tests in the laboratory and related theoretical research, and has high vibration reduction performance and wide applicability.

[0040] In the physical model test of VLFS, the geometric similarity ratio, mass similarity and stiffness similarity of the model are strictly controlled. The test adopts a 1:50 scaling ratio to test the vibration reduction effect of the pore plate structure under different wave conditions. The test covers a wavelength range from 0.6 meters to 7.2 meters, and the prototype wavelength is from 30 meters to 360 meters, covering most of the wavelength ranges of the actual VLFS working environment. Based on the test results, various parameters of the multi-layer pore plate are optimized to make it have excellent vibration reduction performance under different wave periods and mooring methods.

[0041] The multi-layered perforated plate structure of the present invention mainly includes multi-layered perforated plates, fixing devices, and optionally used elastic floating balls. All the absolute dimensions involved in the following multi-layered perforated plate structure are model dimensions, and the prototype dimensions can be scaled according to the actual scale ratio.

[0042] Multi-layered perforated plates

[0043] As Figure 1 shown, the multi-layered perforated plates are the core vibration damping structure of the present invention. By optimizing the number of perforated plate layers, plate spacing, porosity, and installation position, and combining with the VLFS, it can effectively reduce the transmission of wave energy and reduce the hydroelastic response and maximum mooring force.

[0044] Generally, the multi-layered perforated plates are vertically stacked by several layers of perforated plates. Each layer of perforated plate is evenly distributed with openings and fixed together by rigid or elastic connectors. The arrangement methods of the multi-layered perforated plates include single-sided installation (wave-facing side) and double-sided installation (wave-facing side and wave-back side). Specifically, its performance is significantly affected by porosity, plate spacing, number of layers, and submergence depth. This embodiment will elaborate on the design, parameter optimization, and installation method of the multi-layered perforated plates.

[0045] Design of the perforated plates

[0046] In this embodiment, the perforated plates are made of high-strength lightweight materials, and the surface is provided with evenly distributed circular openings, which are used to introduce additional resistance and dissipate wave energy during wave propagation.

[0047] In some embodiments, the material of the perforated plates is selected from acrylic plates, polycarbonate plates, or other composite materials resistant to the marine environment. As an option, metal composite materials with better corrosion resistance can be selected according to actual engineering needs to improve the structural durability.

[0048] As Figure 2 shown, specifically, the opening diameter on the surface of the perforated plates is between 5 mm and 30 mm, and the porosity is controlled between 6% and 15%.

[0049] Structure of the multi-layered perforated plates

[0050] In this embodiment, the multi-layered perforated plate structure is composed of 2 to 4 layers of horizontally stacked perforated plates. The perforated plates are kept at a fixed distance from each other through brackets or connectors, while allowing necessary adjustments.

[0051] As an option, the plate spacing is designed to be 4.2% - 16.7% of the working water depth of the floating body. Generally, a smaller plate spacing is suitable for short-wave band waves and can more effectively dissipate high-frequency wave energy; a larger plate spacing is suitable for long-wave band wave conditions and helps to improve the vibration damping performance during long-wave propagation.

[0052] In a possible implementation, the pore plates are connected by a plurality of stainless steel screws.

[0053] Installation method and submergence depth

[0054] In this embodiment, the multi-layer pore plates are installed on the wave-facing side and / or the wave-back side of the VLFS through rigid or elastic connectors. Specifically, the installation methods include the following:

[0055] As an option, the fixing methods of the pore plates include bolt fixing, slide rail adjustment, and elastic support. Bolt fixing can ensure the rigid stability of the pore plates; slide rail adjustment allows flexible adjustment of the horizontal position and submergence depth; elastic support further optimizes the vibration damping performance by absorbing impact forces.

[0056] Generally, the submergence depth of the pore plates is designed to be 1 to 3 times the wave height below the bottom surface of the floating body. Selecting an appropriate submergence depth can improve the wave dissipation effect of the multi-layer pore plate structure. Usually, the optimal submergence depth of the pore plates is between 1 to 3 times the wave height below the bottom surface of the floating body.

[0057] In some embodiments, the distance between the front edge horizontal position of the wave-facing side pore plate and the front edge of the floating body can be adjusted to 0.25 to 1 times the length of the pore plate. When installed on both sides, the horizontal position of the wave-back side pore plate can be adjusted according to the wavelength to play a role in optimizing the response on the wave-back side.

[0058] In this embodiment, the parameter design of the multi-layer pore plates combines the results of laboratory physical model tests and actual engineering requirements, specifically including the following optimization schemes:

[0059] As a possible optimization method, the optimal values of the porosity in different wavelength ranges can be selected as follows:

[0060] Short wave band (the ratio of wavelength to floating body length is less than or equal to 0.3): The porosity is recommended to be 10% to 15%;

[0061] Long wave band (the ratio of wavelength to floating body length is greater than 0.3): The porosity is recommended to be 6% to 10%.

[0062] Generally, the optimized range of the plate spacing is 4.2% - 16.7% of the working water depth of the floating body, and the optimal value is closely related to the ratio of the wavelength to the floating body length. The submergence depth range is between 1 to 3 times the wave height below the bottom surface of the floating body, and its selection is affected by the wave period and the size of the floating body.

[0063] In a possible implementation, the multi-layer pore plates can also be combined with a real-time adjustment system to dynamically adjust the plate spacing and submergence depth through electric slide rails and sensors to adapt to different wave conditions. Real-time adjustment can further improve the vibration damping performance of the structure and expand its application range.

[0064] Fixing device

[0065] The fixing device is a key connecting component between the multi-layer pore plate structure of the present invention and the very large floating structure (VLFS). Its design has an important impact on the vibration damping performance and installation flexibility of the pore plate. Through the fixing device, the pore plate can be firmly connected to the wave-facing side and / or the wave-back side of the VLFS, and necessary adjustments are allowed to adapt to different wave conditions and engineering requirements.

[0066] Generally, the fixing device needs to meet the requirements of both rigid connection and elastic adjustment, which can not only ensure the stability of the pore plate but also flexibly adjust the horizontal position, water entry depth and other parameters of the pore plate. Specifically, the fixing device includes a bolt fixing component, a slide rail adjustment component and an elastic support component, which can meet various installation requirements of the multi-layer pore plate. The design and working mode of the fixing device are described in detail in this embodiment.

[0067] Bolt fixing component

[0068] In this embodiment, the bolt fixing component is used to achieve the rigid connection between the multi-layer pore plate and the VLFS, and is suitable for use in the case of relatively stable waves or fixed vibration damping parameters.

[0069] Generally, the bolt fixing component is composed of high-strength stainless steel bolts and nuts, and has the characteristics of corrosion resistance and fatigue resistance. As an option, the connection points between the pore plate and the VLFS can adopt the way of reserved holes to facilitate the rapid installation or replacement of the pore plate.

[0070] In some embodiments, the bolt fixing component is used in conjunction with gaskets or rubber support members to further reduce the impact of vibration on the connecting components and improve the impact resistance of the pore plate.

[0071] In one embodiment, a pair of U-shaped connectors are installed on the end side of the VLFS model. Through the screw holes on it, it can be connected to the pore plate structure, so as to fix the pore plate structure directly below the VLFS model, as Figure 3 and Figure 4 shown, which shows the dimensions of the connector and its installation position on the VLFS model.

[0072] Specifically, the bolt fixing component is suitable for the installation of pore plates on the wave-facing side and the wave-back side of the VLFS, and different bolt specifications and spacings can be designed according to needs. For example, for the pore plate on the wave-facing side, larger bolt diameters and dense arrangements can be preferentially used; for the pore plate on the wave-back side, the number of connection points can be appropriately reduced to optimize the overall weight.

[0073] Slide rail adjustment component

[0074] In this embodiment, the slide rail adjustment component is used to flexibly adjust the horizontal position and the water entry depth of the pore plate, and is suitable for use in scenarios where wave conditions are variable or shock absorption performance needs to be optimized.

[0075] In a possible implementation, the slide rail adjustment component includes a fixed slide rail, a sliding block, and a locking mechanism. The fixed slide rail is installed on the wave-facing side or the wave-back side surface of the VLFS. The sliding block enables the horizontal sliding or vertical lifting of the pore plate through the slide rail, and the locking mechanism is used to lock the pore plate after it is adjusted to the target position.

[0076] Generally, the slide rail adjustment component is made of corrosion-resistant aluminum alloy or stainless steel materials to ensure its reliability for long-term use. The guide rail part of the slide rail can be designed as a flat slide rail or a grooved slide rail, and the sliding block is equipped with rollers or sliders to reduce sliding friction. As an option, the slide rail adjustment component can also be combined with an electric drive device to automatically adjust the horizontal position and the water entry depth of the pore plate by monitoring wave conditions through sensors.

[0077] Elastic support component

[0078] In this embodiment, the elastic support component is used to absorb the impact caused by wave forces while fixing the pore plate, and is suitable for use in scenarios where wave conditions are severe or the impact resistance of the pore plate needs to be improved.

[0079] Generally, the elastic support component is composed of an elastic pad, a spring, or a rubber support member. The elastic element is connected between the pore plate and the VLFS by bolts or welding. In some embodiments, the elastic support component can be designed as a multi-segment structure to disperse the impact force and improve its energy absorption capacity.

[0080] As an option, the elastic support component can be used in combination with the slide rail adjustment component, which not only realizes the adjustment function of the pore plate but also enhances the impact resistance of the pore plate. For example, in the case of a seabed anchor chain mooring method, the elastic support component can absorb the vertical component of the wave force, thereby reducing the additional load on the VLFS; in the case of a bollard mooring method, the elastic support component can reduce the impact force of the floating body movement on the pore plate.

[0081] In some embodiments, the design of the fixing device can be optimized in combination with the specific parameters of the multi-layer pore plate. For example:

[0082] As a possible optimization method, the adjustment range of the slide rail adjustment component can be dynamically adjusted according to wave conditions:

[0083] The sliding range of the horizontal slide rail can be designed to be 10% to 30% of the floating body length to meet the optimization requirements for different wave wavelengths;

[0084] The adjustment range of the vertical slide rail can be designed to be 1 to 3 times the wave height of the wave to optimize the adjustment effect of the water entry depth.

[0085] Generally, the bolt diameter of the bolt fixing assembly can be selected between 10 mm and 20 mm according to the size and material of the pore plate, and it is used in combination with an anti-loosening gasket.

[0086] As an extended design, the fixing device can be combined with a real-time adjustment system. By driving the slide rail assembly with a servo motor and combining sensor feedback, automatic adjustment of the position of the pore plate can be achieved to adapt to complex wave environments.

[0087] Elastic floating ball

[0088] Such as Figure 5 As shown, the elastic floating ball is an optional component in the multi-layer pore plate structure of the present invention, which is used to further enhance the vibration damping performance of the pore plate. By arranging the elastic floating ball between the multi-layer pore plates, this component can effectively dissipate wave energy, while providing elastic support and additional resistance to the pore plate, thereby improving the control effect of the hydroelastic response.

[0089] Generally, the elastic floating ball and the multi-layer pore plate are fixed together by a fishing net or a frame, and are applicable to different wavelength ranges under regular waves and irregular waves. Specifically, the diameter, material, density and arrangement method of the elastic floating ball have a significant impact on its vibration damping effect. This embodiment describes in detail the design, parameters and implementation method of the elastic floating ball.

[0090] Design of the elastic floating ball

[0091] In this embodiment, the elastic floating ball is made of a highly elastic rubber or similar material with a density close to that of water, which can produce elastic deformation under wave impact and dissipate energy through the deformation recovery process.

[0092] As an option, the diameter range of the elastic floating ball is designed to be 20 mm to 50 mm. Generally, elastic floating balls with a smaller diameter are suitable for the energy consumption requirements of short-wavelength waves, while elastic floating balls with a larger diameter have a better energy dissipation effect on long-wavelength waves.

[0093] In some embodiments, the material of the elastic floating ball can be selected as a rubber material with good corrosion resistance and anti-aging performance, and the material can be treated for seawater corrosion prevention or added with anti-ultraviolet additives according to specific environmental conditions to enhance its applicability and service life.

[0094] Specifically, the density of the elastic floating ball is preferably 0.95 g / cm 3 to 1.05 g / cm 3 , slightly lower than or close to the density of water, to ensure that the floating ball does not affect the buoyancy of the structure in water and maintains stable elastic recovery performance.

[0095] Arrangement method of elastic floating balls

[0096] In this embodiment, the elastic floating balls are fixed between adjacent pore plates through a fishing net or a frame, forming a floating ball - pore plate combined structure. The arrangement method of the floating balls has a significant impact on its vibration reduction performance.

[0097] As an option, the elastic floating balls can be evenly distributed in the fishing net or the frame, and the spacing between the floating balls preferably ranges from 2 to 5 times the diameter of the floating ball. Generally, a smaller spacing can enhance the collision effect between the floating balls, while a larger spacing is more conducive to the fluid exchange between the waves and the pore plates.

[0098] In some embodiments, the arrangement position of the floating balls can be adjusted according to the wave direction and intensity. For example, dense floating balls are preferentially arranged between the pore plates on the wave - facing side to improve the wave energy dissipation effect on the wave - facing side; while the number of floating balls between the pore plates on the leeward side is appropriately reduced to reduce the obstruction to fluid flow.

[0099] Specifically, when the elastic floating balls are arranged in the middle layer of the multi - layer pore plate structure, their energy absorption performance can be maximized, and they can provide support for the pore plates. In a possible implementation, the floating balls are arranged in the area with a water entry depth of 20% to 80% from the water surface to adapt to the energy concentration range of different wave periods.

[0100] Fixing method of elastic floating balls

[0101] In this embodiment, the elastic floating balls are fixedly connected to the pore plates through a fishing net or a frame. The fishing net is usually made of high - strength and corrosion - resistant polyethylene fibers, and its mesh size is preferably 0.5 to 0.8 times the diameter of the floating ball to ensure that the floating balls can be stably positioned in the fishing net.

[0102] In some embodiments, the fixing method of the elastic floating balls can also be used in combination with a slide rail adjustment device to adjust the arrangement position and depth of the floating balls. For example, by adjusting the vertical slide rail of the frame, the real - time adjustment of the arrangement depth of the floating balls can be achieved, so as to adapt to the changes of different wave conditions.

[0103] Parameter optimization of elastic floating balls

[0104] In this embodiment, the diameter, density and arrangement method of the elastic floating balls are all optimized through experiments to ensure that their vibration reduction performance reaches the best state under regular wave and irregular wave conditions.

[0105] Generally, the diameter of the floating ball is selected in the range of 20 mm to 50 mm, and the floating ball with a diameter of 30 mm is suitable for most wave conditions. Under regular wave conditions, the recommended distance between floating balls is about 3 times their diameter; under irregular wave conditions, the distance can be appropriately reduced to enhance the collision effect between floating balls.

[0106] As a possible optimization method, the arrangement density of the floating balls can be adjusted according to the wave period. For example, under short-period wave conditions, it is recommended to arrange 200 to 300 floating balls per square meter; under long-period wave conditions, it is recommended to arrange 100 to 150 floating balls per square meter.

[0107] Scope of application of elastic floating balls

[0108] In this embodiment, the elastic floating balls are applicable to various scenarios under the action of regular waves and irregular waves, and can effectively enhance the vibration reduction performance of the multi-layer perforated plates.

[0109] Under the seabed chain mooring method, the elastic floating balls can reduce the vertical component of the wave force, thereby optimizing the motion response of the VLFS; under the bollard mooring method, the elastic floating balls can reduce the impact force between the floating body and the cable, further improving the safety of the mooring system.

[0110] As an extended design, the elastic floating balls can also be combined with an intelligent adjustment system to adjust the arrangement density and depth of the floating balls in real time by monitoring the wave conditions, so as to achieve more precise vibration reduction control.

[0111] Generally speaking, the present invention effectively reduces the hydroelastic response and the maximum mooring force of the floating body under wave action by optimizing the number of layers, porosity, plate spacing and water depth of the perforated plates, and combining rigid or elastic fixing devices with the floating body structure. The multi-layer perforated plates are made of high-strength lightweight materials with uniformly distributed openings on the surface, and elastic floating balls can be arranged between the perforated plates according to needs to further improve the vibration reduction performance and wave energy dissipation capacity. The present invention is applicable to various wave conditions and floating body application scenarios, and its design is verified by physical model tests, which can meet the safety and stability requirements of super-large floating body structures in complex marine environments, and provides an efficient and flexible solution for floating body vibration reduction technology.

[0112] To better understand the present invention, the above solutions will be described in detail below in conjunction with specific embodiments.

[0113] The following examples were all carried out relying on the long and short period combined wave-making flume of the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The effective size of the flume is 40.0m×24.0m×1.2m, the maximum working water depth is 0.9m, the maximum wave height is 0.25m, and the period range is from 0.5s to 5.0s. The tests are based on a push-plate wave maker to generate regular waves and irregular waves, and are used to study the vibration reduction effect of multi-layer perforated plate structures in very large floating structures (VLFS).

[0114] To ensure the similarity between the model test and the actual project, the following examples follow the gravity similarity criterion and the elastic similarity criterion. Through multiple adjustments, a sandwich structure composed of 2 layers of aluminum plates and 2 layers of polyethylene foam plates is used as the VLFS model. The geometric dimensions refer to the first-phase test of the Japan Mega-Float Technology Research Association and are designed according to a 1:50 scale ratio. The model is 6m long, 1.25m wide, and 78mm thick. The VLFS model is arranged at the center of the flume. In the test, the influence of multi-layer perforated plates on the hydroelastic response and mooring force of VLFS under different wave conditions was studied. Table 1 shows the main parameters of the waves and the VLFS model. The material composition of the VLFS model is as Figure 6 shown, and the arrangement of the VLFS model in water is as Figure 7 shown.

[0115] Table 1 Main parameters of waves and VLFS model

[0116] parameter model prototype Length (m) 6 300 Width (m) 1.25 62.5 Thickness (m) 0.078 3.9 Draft (m) 0.02 1 <![CDATA[Flexural rigidity (N·m 2 )]]> <![CDATA[2.2742×10 4 > <![CDATA[7.1069×10 12 > Water depth (m) 0.6 30 Wavelength (m) 0.6～7.2 30～360 Mass (kg) 92 <![CDATA[1.15×10 7 >

[0117] Two mooring methods are adopted: seabed chain mooring and bollard mooring, as Figure 8 shown. High-precision optical measurement equipment Optrak Certus and multi-channel wave gauges are also arranged on the test model to record the motion response, wave characteristics, and mooring force of VLFS.

[0118] Example 1:

[0119] This example is based on the seabed chain mooring method and studies the influence of different porosities on the vibration reduction effect of multi-layer perforated plate structures. Through the analysis of 2-layer, 3-layer, and 4-layer perforated plate structures, the regulation effects on the hydroelastic response and maximum mooring force of VLFS under different wavelength conditions are tested. The water depth of the perforated plate in this example is 0.12m, the plate spacing is 0.05m, and the ratio range of the wavelength to the VLFS length is 0.1 - 1.0.

[0120] In this example, through the comparative analysis of multi-layer perforated plates with different porosities (0.06, 0.1, 0.15), the following laws are obtained:

[0121] Influence on hydroelastic response

[0122] The multi-layered porous plate structures with different porosities show consistent regularity in the hydroelastic response of VLFS with respect to the change in wavelength. When the wavelength is short (the ratio of the wavelength to the length of VLFS ranges from 0.1 to 0.2), the hydroelastic response decreases with the increase in porosity. A larger porosity is more conducive to dissipating wave energy and reducing the response amplitude of the floating body at this time.

[0123] However, when the wavelength is in the intermediate range (the ratio of the wavelength to the length of VLFS ranges from 0.3 to 0.4), the hydroelastic response increases with the increase in porosity, indicating that a larger porosity will cause a greater response of the floating body under medium-wavelength conditions. For longer wavelengths (the ratio of the wavelength to the length of VLFS ranges from 0.5 to 0.6), the multi-layered porous plates with different porosities may all achieve the best vibration reduction effect, and the specific effect is related to the wavelength.

[0124] When the wavelength further increases (the ratio of the wavelength to the length of VLFS is greater than 0.6), the sensitivity of the hydroelastic response to the change in porosity decreases significantly, indicating that the influence of porosity on the response of the floating body is smaller under long-wave conditions.

[0125] Influence of the maximum mooring force

[0126] The influence of the multi-layered porous plate structures with different porosities on the maximum mooring force of the VLFS model. For the 2-layer porous plate structure, when the porosity is P = 0.15, the maximum mooring force is the smallest, while when P = 0.1, the maximum mooring force reaches the maximum value.

[0127] For the 3-layer porous plate structure, when the ratio of the wavelength to the length of VLFS is equal to 0.5, the structure with a porosity of P = 0.15 has the maximum mooring force; while when the ratio of the wavelength to the length of VLFS is equal to 0.7, the structure with a porosity of P = 0.06 has the maximum mooring force. Under other wavelength conditions, the influence of different porosities on the maximum mooring force is relatively close.

[0128] For the 4-layer porous plate structure, when the ratio of the wavelength to the length of VLFS is in the range of 0.5 to 0.7, the structure with a porosity of P = 0.06 has the maximum mooring force, while the structure with a porosity of P = 0.15 has the minimum mooring force. Under other wavelength conditions, the change in porosity has a relatively small influence on the maximum mooring force.

[0129] This embodiment shows that the selection of porosity in the multi-layered porous plate structure has a significant influence on the hydroelastic response and mooring force of VLFS. Specifically:

[0130] A larger porosity is suitable for short-wave conditions and can more effectively reduce the hydroelastic response;

[0131] A medium porosity may cause a higher hydroelastic response in some wavelength ranges;

[0132] The porosity has little effect on the long-wave condition, but its effect on the maximum mooring force varies with the number of plate layers and the wavelength.

[0133] In practical engineering, the appropriate porosity can be selected according to the wave conditions of the water area to optimize the vibration reduction effect within different wavelength ranges.

[0134] Example 2:

[0135] This example studied the influence of multi-layer porous plate structures with different porosities on the hydroelastic response and the maximum mooring force of VLFS under the mooring method of a mooring post. In the example, porous plate structures with 2, 3, and 4 layers were adopted, and their vibration reduction effects and mechanical properties were analyzed within the ratio of the wavelength to the length of VLFS equal to 0.1 - 1.0. The test parameters included a draft of 0.12 m and a plate spacing of 0.1 m (for the 2-layer structure) and 0.05 m (for the 3-layer and 4-layer structures).

[0136] Influence on the hydroelastic response

[0137] The influence of different porosities on the hydroelastic response shows a significant pattern with the change of wavelength:

[0138] When the ratio of the wavelength to the length of VLFS is equal to 0.1 - 0.2, the hydroelastic response of VLFS decreases with the increase of porosity. At this time, a higher porosity (0.1 or 0.15) can dissipate wave energy more efficiently and reduce the response amplitude on the wave-facing side.

[0139] When the ratio of the wavelength to the length of VLFS is equal to 0.3 - 0.5, the hydroelastic response on the wave-facing side increases with the increase of porosity, while the response on the lee side changes little. This indicates that under medium-wavelength conditions, a larger porosity may lead to higher fluid resistance and cause greater deformation of the floating body.

[0140] When the ratio of the wavelength to the length of VLFS is greater than 0.5, the sensitivity of the hydroelastic response to porosity decreases significantly, indicating that under long-wave conditions, the porosity of the porous plate has a limited influence on the vibration reduction effect.

[0141] The experiment also shows that the influence patterns of the 2-layer, 3-layer, and 4-layer porous plate structures on the hydroelastic response are similar, but the increase in the number of layers will strengthen their effect on the wave-facing side.

[0142] Influence on the maximum mooring force

[0143] The influence of different porosities on the maximum mooring force of VLFS:

[0144] For the two-layer perforated plate structure, when the ratio of the wavelength to the VLFS length is less than or equal to 0.4, the maximum mooring force is less than that without the perforated plate structure, indicating that a larger porosity can effectively reduce the peak of the mooring force; when the ratio of the wavelength to the VLFS length is greater than 0.4, the presence of the perforated plate will increase the peak of the mooring force.

[0145] For the three-layer and four-layer perforated plate structures, when the ratio of the wavelength to the VLFS length is less than or equal to 0.6, the maximum mooring force is less than or close to that without the perforated plate; while when the ratio of the wavelength to the VLFS length is greater than 0.6, the maximum mooring force increases significantly with the increase in the number of perforated plate layers.

[0146] Experiments show that the three-layer and four-layer perforated plate structures may cause larger additional forces under long-wave conditions, and optimization needs to be considered comprehensively according to engineering requirements.

[0147] This embodiment shows that different porosities have a significant impact on the hydroelastic response and maximum mooring force of the VLFS. Specifically:

[0148] The optimization of porosity needs to be determined according to the wavelength range: under short-wave conditions, a larger porosity (such as 0.15) has a better effect; while under medium-wavelength conditions, a smaller porosity (such as 0.06) has a better effect; under long-wave conditions, the influence of porosity on the vibration reduction effect is smaller.

[0149] In terms of the maximum mooring force, porosity has little influence on short-wave and medium-wave conditions, but has a significant influence on long-wave conditions. The combination of the number of layers and porosity needs to be reasonably selected to reduce the additional mooring force.

[0150] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made therein without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-layer porous plate structure for shock absorption of super-large floating bodies, characterized in that: The invention comprises a plurality of horizontally arranged porous plates, which are interconnected to form a multi-layer porous plate structure, each of which is an acrylic plate or a polycarbonate plate, and the surface of the porous plate is provided with evenly distributed openings, and the multi-layer porous plates are connected to the super-large floating structure through a fixing device, so as to reduce the hydroelastic response and the maximum mooring force of the floating body, wherein: The porosity of the porous plate is 6% to 15%. The number of porous plate layers is 2 to 4. The spacing between adjacent porous plates is 4.2% to 16.7% of the working water depth of the floating body. The immersion depth of the porous plate is 1 to 3 times the wave height below the bottom of the floating body; The horizontal position of the aperture plate can be adjusted, specifically: The distance between the front position of the porous plate on the wave-facing side and the front position of the floating body model is 0.25 to 1 times the length of the porous plate; The rear edge position of the aperture plate on the back-wave side can be adjusted to the wave-facing direction or the back-wave direction of the floating body according to the wavelength, and the adjustment range is 0.25 times to 1 times the length of the aperture plate; The connection between the aperture plate and the floating body is a rigid connection or an elastic connection, which is fixed by bolts, adjustable installation of slide rails or elastic support to adapt to different wave frequencies and mooring methods; The multi-layer porous plate structure is installed on the wave-facing side or both the wave-facing side and the wave-repelling side of the floating body. When installed on both sides, the porosity and the number of layers of the wave-facing side porous plate and the wave-repelling side porous plate can be adjusted respectively to optimize the vibration reduction effect of the wave-facing side and the wave-repelling side; An elastic buoy is arranged between adjacent porous plates on the wave-facing side or the wave-back side. The elastic buoy is fixed between adjacent porous plates through a fishing net or a frame structure. The elastic buoy is made of rubber with a density close to that of water. The multi-layer porous plate structure adjusts the wave reflection coefficient, transmission coefficient and energy dissipation coefficient of the floating body by changing the porosity, plate spacing, number of layers, horizontal position and water immersion depth of the porous plate to adapt to different marine environments and wave conditions.

2. A multi-layer porous plate structure for shock absorption of a super-large floating body according to claim 1, characterized in that: The multi-layer porous plate structure is suitable for a floating system using a seabed anchor chain mooring method or a mooring bollard mooring method, specifically: In the submarine anchor chain mooring mode, the double-side installation mode is adopted; In the bollard mooring mode, the single-side installation mode on the wave-facing side is adopted.

3. The multi-layer porous plate structure for shock absorption of a super-large floating body according to claim 1, characterized in that: The multi-layer porous plate structure can reduce the maximum value of the hydroelastic response of the wave-facing side and the wave-rear side of the floating body under the wave condition where the ratio of the wavelength to the floating body length is less than 0.3; under the wave condition where the ratio of the wavelength to the floating body length is greater than 0.3, the vibration reduction effect is concentrated on the wave-facing side of the floating body.

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