Vibration Reduction Method for Ship Equipment Based on Waveform Conversion and Surface Wave Attenuation

Abstract

The present invention discloses a vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation, belonging to the technical field of vibration isolation of ship equipment, including: establishing a simulation calculation model of the equipment-base-hull structure coupled vibration system according to the preset types of ship mechanical equipment, layout drawings and structure drawings to determine the vibration reduction design requirements of the system; designing an initial vibration reduction structure for the ship equipment according to the vibration reduction design requirements of the system; establishing a simulation calculation model of the equipment-surface wave vibration reduction structure-base-hull structure according to the simulation calculation model of the equipment-base-hull structure coupled vibration system and the initial vibration reduction structure for the ship equipment to evaluate whether the vibration reduction effect of the initial vibration reduction structure for the ship equipment meets the requirements of the equipment vibration reduction index. If not, redesign until the final vibration reduction structure for the ship equipment is obtained. This method is based on the principles of waveform conversion and liquid surface wave attenuation, breaks through the limitations of traditional vibration reduction structure design methods, and effectively enhances the dissipation of vibration energy.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration isolation and reduction for ship equipment, and particularly relates to a vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation. Background Art

[0002] The ship vibration reduction structure is an important way to suppress the radiation of the vibration energy of mechanical equipment to the hull structure and the surrounding flow field. The traditional vibration isolation and reduction structure is designed based on the classical vibration isolation theory, relying on the point-to-point transmission of excitation force by vibration isolators, and requiring that the ratio of the excitation force frequency to the natural frequency of the vibration reduction element is not less than To further improve the vibration isolation and reduction effect towards low frequencies, active control needs to be adopted or the structural natural frequency needs to be reduced as much as possible, which is not conducive to the lightweight design of the structure. And using metamaterials or meta-structures cannot guarantee the structural strength. Therefore, new vibration reduction methods need to be explored.

[0003] The vibration reduction design methods in the related technologies mainly include the following two: One is the vibration reduction design method for mechanical equipment. Its vibration reduction design method mainly combines the parameter selection of the vibration reduction device, the design of the vibration reduction device with the equipment, obtains the vibration mode, natural frequency and maximum static displacement of the vibration reduction device through modal analysis and static structural analysis, evaluates the vibration mode of the vibration reduction device and calculates the vibration reduction efficiency in combination with the environmental vibration conditions, and finally completes the vibration reduction device that meets the vibration mode, vibration reduction efficiency and maximum static displacement. However, this scheme only considers the vibration reduction under the system mode and does not consider the broadband vibration reduction ability during equipment operation, resulting in poor vibration reduction effect. The other is a semi-active vibration reduction base and control method. This vibration reduction base includes an upper end plate and a lower end plate. There are several cylindrical particle dampers between the upper end plate and the lower end plate. Solid particles are placed in the particle dampers. A coil is sleeved outside the particle dampers, and the coil is connected to a controller. The controller is connected to the lower end plate through a sensor. The particle dampers, the coil and the controller form a closed current loop. When vibration occurs in the low frequency band, the particles in the upper half of the particle damper are excited and participate in the consumption of vibration energy, and at the same time drive some of the particles in the lower half to also participate in the collision and friction, so that the device can achieve good vibration reduction and low vibration reduction noise. However, the manufacturing process of this method is relatively complex and the cost is relatively high, making it difficult to be widely applied.

[0004] In summary, there is an urgent need for a new vibration reduction structure and method for ship equipment to improve the vibration reduction effect. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related technologies to some extent.

[0006] For this purpose, an object of the present invention is to propose a vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation.

[0007] Another object of the present invention is to propose a computer device.

[0008] Another object of the present invention is to provide a non-transitory computer-readable storage medium.

[0009] To achieve the above object, an embodiment of the present invention on one hand provides a vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation, including the following steps: Step S1, according to the preset types of ship mechanical equipment, layout drawings and structure drawings, establish a simulation calculation model of the equipment-base-hull structure coupled vibration system to determine the vibration reduction design requirements of the system; Step S2, design an initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation according to the vibration reduction design requirements of the system; Step S3, establish a simulation calculation model of the equipment-surface wave vibration reduction structure-base-hull structure according to the simulation calculation model of the equipment-base-hull structure coupled vibration system and the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation, and evaluate whether the vibration reduction effect of the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation meets the equipment vibration reduction index requirements. If not, iterate and execute Step S2 to redesign the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation until it meets the requirements, and obtain the final ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation.

[0010] The vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation in the embodiment of the present invention utilizes the characteristic that elastic waves will undergo waveform conversion in different media. By adding a liquid vibration isolation layer to the vibration reduction structure, the vibration waves transmitted to the vibration reduction structure are forced to undergo waveform conversion, converting the bending waves propagating in the solid into longitudinal waves in the liquid, effectively reducing the transmission of vibration energy; utilizing the principle that the wave energy is mainly concentrated on the liquid surface and decays with the depth from the surface, by reasonably dividing and discretizing the panel structure arranged on the surface of the vibration isolation liquid layer, a surface wave environment is constructed, effectively enhancing the dissipation of vibration energy; breaking through the limitation of the natural frequency ratio in the design of traditional vibration reduction structures, compared with the limitations of large mass or insufficient stability that may be brought about by the traditional passive vibration isolation and reduction design method when further improving the low-frequency vibration isolation and reduction level of the structure, it has the advantages of lightweight and more efficient vibration reduction effect; has high versatility, good practicability and a wide range of application fields, and is convenient for technology promotion.

[0011] In addition, the vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation according to the above embodiment of the present invention may further have the following additional technical features:

[0012] Further, in an embodiment of the present invention, the step S1 specifically includes: step S101, determining the equipment vibration reduction index requirements according to the preset types of ship mechanical equipment; step S102, establishing a simulation calculation model of the equipment-base-hull structure coupled vibration system according to the preset layout plan and structure diagram; step S103, using the vibration acceleration level and vibration level drop as the vibration reduction effect evaluation indexes, and calculating the initial system vibration characteristics of the equipment-base-hull structure coupled vibration system simulation calculation model by using numerical methods; step S104, comparing the initial system vibration characteristics with the preset indexes to determine the vibration reduction design requirements of the system.

[0013] Further, in an embodiment of the present invention, the step S2 specifically includes: step S201, determining the equipment mass and momentum characteristics during operation according to the preset types of ship mechanical equipment, layout plan, structure diagram and the vibration reduction design requirements of the system, and further determining the stiffness requirements of the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation; step S202, determining the equipment foot position and excitation characteristics according to the preset types of ship mechanical equipment, layout plan, structure diagram and the vibration reduction design requirements of the system, and further determining the number and arrangement positions of the sub-panels of the chain discrete panel; step S203, determining the coverage range and the number of liquid sacs of the vibration isolation liquid layer according to the arrangement position of the chain discrete panel, and determining the thickness of the vibration isolation liquid layer according to the vibration reduction design requirements and surface wave attenuation characteristics; step S204, determining the size of the limit box-shaped structure according to the coverage range and thickness of the vibration isolation liquid layer; step S205, determining the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation according to the stiffness requirements, the number and arrangement positions of the sub-panels of the chain discrete panel, the coverage range of the vibration isolation liquid layer, the number and thickness of the liquid sacs, and the size of the limit box-shaped structure.

[0014] Further, in an embodiment of the present invention, the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation includes: a chain discrete panel, a vibration isolation liquid layer and a limit box-shaped structure, wherein the chain discrete panel is arranged on the surface of the vibration isolation liquid layer, and the top of the chain discrete panel has a support end surface connected to the equipment; the vibration isolation liquid layer is arranged in the limit box-shaped structure; the bottom of the limit box-shaped structure is connected to the base panel or raft structure by bolts.

[0015] Further, in an embodiment of the present invention, the chain discrete panel includes a sub-panel structure and a hinge connection structure, wherein there is a gap between adjacent sub-panel structures, and the adjacent sub-panel structures are connected by the hinge connection structure.

[0016] Further, in an embodiment of the present invention, the vibration isolation liquid layer includes a plurality of liquid sacs, and each liquid sac includes a hyperelastic material sac body and a contained liquid.

[0017] Further, in an embodiment of the present invention, the limiting box-shaped structure is an open box-shaped structure, the height of which is lower than the thickness of the vibration isolation liquid layer, and there is no direct contact with the chain-type discrete panel.

[0018] Further, in an embodiment of the present invention, step S3 specifically includes: step S301, based on the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation, on the basis of the simulation calculation model of the equipment-pedestal-hull structure coupling vibration system, establish a simulation calculation model of the equipment-surface wave vibration reduction structure-pedestal-hull structure, and use the vibration acceleration level and the vibration level drop as the evaluation indexes of the vibration reduction effect to calculate and optimize the vibration characteristics of the system; step S302, compare the optimized system vibration characteristics with the equipment vibration reduction index requirements and the system vibration reduction design requirements to obtain the vibration reduction effect of the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation; step S303, determine whether the vibration reduction effect meets the preset vibration reduction requirements. If it does not meet the vibration reduction requirements, then iteratively execute step S2 to redesign the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation until it is satisfied, and obtain the final ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation.

[0019] To achieve the above object, another embodiment of the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the ship equipment vibration reduction method based on waveform conversion and surface wave attenuation as described in the above embodiment.

[0020] To achieve the above object, yet another embodiment of the present invention provides a non-temporary computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the ship equipment vibration reduction method based on waveform conversion and surface wave attenuation as described in the above embodiment.

[0021] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0022] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, in which:

[0023] Figure 1 It is a flowchart of a ship equipment vibration reduction method based on waveform conversion and surface wave attenuation according to an embodiment of the present invention;

[0024] Figure 2 The detailed design flowchart of the vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation according to an embodiment of the present invention;

[0025] Figure 3 The schematic diagram of the vibration reduction structure of ship equipment based on waveform conversion and surface wave attenuation according to an embodiment of the present invention;

[0026] Figure 4 The specific schematic diagram of the vibration reduction structure of ship equipment based on waveform conversion and surface wave attenuation according to an embodiment of the present invention;

[0027] Figure 5 The schematic diagram of the waveform conversion principle according to an embodiment of the present invention;

[0028] Figure 6 The schematic diagram of the vibration reduction principle of surface wave attenuation according to an embodiment of the present invention;

[0029] Figure 7 The comparison diagram of the vibration isolation effect curves of the final vibration reduction structure of ship equipment according to an embodiment of the present invention.

[0030] Explanation of the reference numerals: 1 - chain - type discrete panel, 2 - vibration isolation liquid layer, 3 - limit box - type structure, 4 - sub - panel structure, 5 - hinge connection structure, 6 - liquid sac, 7 - hull structures such as base panel / raft frame, 8 - marine equipment. Detailed implementation manners

[0031] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] The vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation proposed according to an embodiment of the present invention will be described below with reference to the drawings.

[0033] Figure 1 It is the flowchart of the vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation according to an embodiment of the present invention.

[0034] As Figure 1 and 2 shown, the vibration reduction method for ship equipment based on waveform conversion and surface wave attenuation includes the following steps:

[0035] In step S1, according to the preset types of ship mechanical equipment, layout drawings, and structure drawings, a simulation calculation model of the equipment-base-hull structure coupled vibration system is established to determine the vibration reduction design requirements of the system.

[0036] Further, in an embodiment of the present invention, step S1 specifically includes:

[0037] Step S101, determining the vibration reduction index requirements of the equipment according to the preset types of ship mechanical equipment.

[0038] Among them, the equipment types include common ship mechanical equipment such as the main engine, auxiliary equipment, and pump equipment with vibration reduction requirements. The equipment information to be clarified includes but is not limited to the equipment weight and size, equipment installation conditions, equipment protection level, and allowable maximum offset, etc.; the equipment vibration reduction index requirements include the vibration index requirements of the equipment operating environment and the vibration reduction level requirements that the equipment vibration reduction structure needs to achieve.

[0039] Step S102, establishing a simulation calculation model of the equipment-base-hull structure coupled vibration system according to the preset layout drawings and structure drawings.

[0040] Specifically, during the modeling process, the equipment is simplified into a mean cube structure with equal mass. The simplification of the base structure and hull structure models must be consistent with the total mass and mass distribution of the original models, and the models can be reasonably truncated according to the calculation efficiency requirements; the connection of the vibration isolators between the equipment and the base is simplified into a spring connection; on the basis of establishing the structure model, the corresponding material properties are given to the structure model, including necessary material parameters such as the density of the structural material, damping, Young's modulus, and Poisson's ratio, to ensure that the material information of the established model is consistent with the actual structure; the boundary conditions are set according to the actual application situation; according to the calculation frequency band requirements, the finite element model is meshed to ensure that the meshed model has sufficient calculation accuracy and high calculation efficiency.

[0041] Step S103, taking the vibration acceleration level and vibration level drop as the vibration reduction effect evaluation indexes, and using numerical methods to calculate the initial system vibration characteristics of the equipment-base-hull structure coupled vibration system simulation calculation model.

[0042] Specifically, several uniformly distributed reference points are selected on the base panel and the hull structure as excitation points and response pickup points respectively. The selection of the reference points should be based on the actual structural dimensions of the base panel and the hull structure, and it should be ensured that they are uniformly distributed in each part of the structure. The number of reference points is usually 4 - 8;

[0043] Vibration acceleration level L a The calculation formula is:

[0044]

[0045] Wherein, a is the generalized vibration response at the reference point, and a0 is the generalized vibration response at the excitation point.

[0046] The calculation formula for the vibration level drop is:

[0047]

[0048] Wherein, Z0 is the input impedance, Z n is the transfer impedance, L Z0 is the input impedance level, L Z1 is the transfer impedance level.

[0049] Step S104: Compare the initial system vibration characteristics with the preset indexes to determine the system vibration reduction design requirements.

[0050] It should be noted that if the calculated structural vibration acceleration level and vibration level drop meet the system index requirements, there is no need for vibration reduction design. If they do not meet the index requirements, the system vibration reduction design requirements are determined according to the over-standard situation of the vibration acceleration level and the non-compliance situation of the vibration level drop, including the vibration level drop requirements of the vibration reduction structure and the requirements for the system vibration acceleration level.

[0051] In step S2, an initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation is designed according to the system vibration reduction design requirements, which can be simply referred to as the surface wave vibration reduction structure.

[0052] Furthermore, in an embodiment of the present invention, step S2 specifically includes:

[0053] Step S201: Determine the equipment mass and momentum characteristics during operation according to the preset ship mechanical equipment type, layout drawing, structure drawing and system vibration reduction design requirements, and then determine the stiffness requirements of the ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation, wherein the stiffness requirements include static stiffness requirements and dynamic stiffness requirements.

[0054] Step S202: Determine the equipment foot position and excitation characteristics according to the preset ship mechanical equipment type, layout drawing, structure drawing and system vibration reduction design requirements, and then determine the number and arrangement position of the sub-panels of the chain-type discrete panel.

[0055] Specifically, according to the distribution of the equipment feet, the overall size of the chain-type discrete panel structure is initially determined so that the equipment is located in the middle of the panel structure during installation, and the panel area is slightly larger than the equipment; according to the equipment foot position and quantity, the arrangement position and quantity of the sub-panels are initially determined so that the equipment foot position is maintained at the center position of the sub-panel structure directly below it, and the sub-panel area is larger than the foot; according to the equipment excitation characteristics, the sub-panel structure size and the gap between adjacent sub-panel structures are determined, and adjacent sub-panels are connected by hinges; according to the strength and stiffness requirements of the vibration reduction structure, the thickness and material of the chain-type discrete panel are determined.

[0056] Step S203: Determine the coverage range of the vibration isolation liquid layer and the number of liquid sacs according to the arrangement position of the chain - type discrete panel, and determine the thickness of the vibration isolation liquid layer according to the vibration reduction design requirements and the surface wave attenuation characteristics.

[0057] Specifically, determine the area of the vibration isolation liquid layer according to the overall area of the chain - type discrete panel, so that the area of the vibration isolation liquid layer completely covers and is slightly larger than the panel on all four sides; determine the number of liquid sacs included in the vibration isolation liquid layer according to the arrangement position of the sub - panel structure of the chain - type discrete panel, and it is a better choice to arrange 2 - 3 sub - structure panels on the surface of a single liquid sac; determine the thickness of the vibration isolation liquid layer according to the equipment excitation frequency and the surface wave attenuation characteristics; determine the liquid medium in the liquid sac and the material of the sac body according to the fluctuation characteristics and energy loss characteristics of the fluid medium.

[0058] Step S204: Determine the size of the limit box - type structure according to the coverage range and thickness of the vibration isolation liquid layer. Specifically, the limit box - type structure is a completely open box - type structure, and the liquid sac is placed inside the box - type structure. Determine the bottom area of the limit box - type structure according to the area of the vibration isolation liquid layer, and the bottom area is the same as the area of the vibration isolation liquid layer; determine the height of the limit box - type structure according to the thickness of the vibration isolation liquid layer, and the height of the limit box - type structure is less than the thickness of the vibration isolation liquid layer, so that it has no direct contact with the chain - type discrete panel structure in both the static and operating states of the equipment; determine the thickness and material of the limit box - type structure according to the requirements of structural strength and stiffness.

[0059] Step S205: Determine the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation according to the stiffness requirements, the number and arrangement position of the sub - panels of the chain - type discrete panel, the coverage range of the vibration isolation liquid layer, the number and thickness of the liquid sacs, and the size of the limit box - type structure. Among them, the initial ship equipment vibration reduction structure includes parameters such as the size, material, position, and number of the chain - type discrete panel, the vibration isolation liquid layer, and the box - type limit structure.

[0060] It should be noted that, as Figure 3 shown, this surface wave vibration reduction structure is used between the ship mechanical equipment 8 and the structures such as the equipment base / raft 7, and includes: a chain - type discrete panel 1, a vibration isolation liquid layer 2, and a limit box - type structure 3. Among them, the chain - type discrete panel 1 is arranged on the surface of the vibration isolation liquid layer 2, and the top of the chain - type discrete panel 1 has a support end surface connected to the equipment; the vibration isolation liquid layer 2 is arranged in the limit box - type structure 3. The bottom of the limit box - type structure 2 is connected to the base panel or raft structure by bolts; the vibration energy dissipation is realized by using the waveform conversion between solid - liquid media during the vibration wave transmission process and the principle that the liquid surface wave attenuates with depth.

[0061] Furthermore, in an embodiment of the present invention, the chain - type discrete panel 1 includes a number of discontinuous sub - panel structures 4 and hinge connection structures 5. Among them, there are gaps between adjacent sub - panel structures 4, and they are connected by hinge connection structures 5.

[0062] Specifically, as Figure 3 shown, the chain - type discrete panel 1 is arranged on the surface of the vibration isolation liquid layer 2. The top of the chain - type discrete panel 1 has a supporting end surface connected to the marine equipment 8, which is conducive to effectively isolating and controlling the elastic waves in the panel response surface, constructing a surface wave environment on the liquid surface, increasing the energy dissipation, and thus effectively improving the vibration isolation and shock absorption performance of the base.

[0063] Furthermore, in an embodiment of the present invention, the vibration isolation liquid layer 2 includes a plurality of liquid sacs 6. The liquid sac includes a hyper - elastic material sac body and the contained liquid.

[0064] It should be noted that the contained liquid is mainly a low - density and high - viscosity liquid, which is conducive to forcibly converting the vibration waves transmitted to the vibration - damping structure and attenuating them in the depth direction in the liquid.

[0065] Furthermore, in an embodiment of the present invention, the limit box - type structure is an open - top box - type structure, with a height lower than the thickness of the vibration isolation liquid layer and having no direct contact with the chain - type discrete panel.

[0066] Specifically, as Figure 4 shown, the vibration isolation liquid layer 2 is arranged in the box - type limit structure 3. The box - type limit structure 3 is an open - top box - type structure, with a height lower than the thickness of the vibration isolation liquid layer, which is conducive to avoiding rigid contact with the panel structure, reducing energy transfer. The bottom of the box - type limit structure 3 is connected to the base panel or the raft structure 7 by bolts.

[0067] Still further, as Figure 5 shown, the waveform conversion described in the embodiment of the present invention is based on the principle that the propagation forms of elastic waves are different in different media. By changing the physical properties of the vibration - damping structure suddenly, the transmission characteristics of the vibration waves are changed. The transverse waves propagating in the panel structure are converted into longitudinal waves propagating in the liquid sacs through the vibration isolation liquid layer, as follows:

[0068] Based on the elastic wave theory, the bending vibration equation of an infinite undamped homogeneous thin plate under transverse harmonic excitation is as follows:

[0069]

[0070] where D is the bending stiffness of the plate, is the Laplace operator, w is the vertical deflection of the plate, ρ is the material density of the plate, h is the thickness of the plate, t is time, F0 is the amplitude per unit area on the plate surface, e is the base of the natural logarithm, j is the imaginary unit, k x is the wave number of the plate in the x - direction, k y is the wave number of the plate in the y - direction, and x, y, z are the coordinates of the origin in the mid - plane of the plate.

[0071] When the vibration energy is transmitted into the liquid, the particle velocity of the fluid perpendicular to the plate surface is:

[0072]

[0073] where v z is the particle velocity, ρ0 is the liquid density, and p is the acoustic pressure of the fluid in the direction perpendicular to the plate surface.

[0074] The wave impedance (also known as the acoustic radiation impedance) in the fluid can be expressed as:

[0075]

[0076]

[0077] where Z wf is the acoustic radiation impedance, p is the acoustic pressure of the fluid in the direction perpendicular to the plate surface, v z is the particle velocity, ρ0 is the liquid density, c is the sound speed in the liquid, k p is the bending wave number in the plate, and k0 is the wave number in the liquid.

[0078] When there is a liquid load on one side of the flat plate structure, it can be seen from the above formula that when k0 > k p , the presence of the liquid load will dissipate the vibration energy of the structure, and can effectively reduce the vibration level of the structure.

[0079] As Figure 4 shown, the surface wave attenuation in the embodiment of the present invention is based on the principle that the fluid fluctuation in the liquid medium is mainly concentrated on the liquid surface, the surface wave energy accounts for 70% of the total energy, and the trajectory of the fluid particle movement in the linear wave theory is an ellipse, and the ellipse radius decays along the water depth. By adding a liquid medium to the vibration damping structure and constructing a surface wave environment through a discrete panel, the dissipation of vibration energy is increased, specifically as follows:

[0080] The vibration isolation liquid layer is the main structural design in the embodiment of the present invention. The water wave attenuation theory on which it is based, taking water as an example, the wave equation formula is as follows:

[0081]

[0082] where ρ is the density of the elastic body, and λ, μ are the Lame constants,

[0083] The wave equation is separated into independent equations of scalar potential and vector potential:

[0084]

[0085] where Φ is the scalar potential and Ψ is the vector potential.

[0086] The assumed solution of the equation is as follows:

[0087]

[0088] where k s = ω / c s , C s is the surface wave sound velocity, α and β are undetermined coefficients reflecting the attenuation degree of the surface wave. From the boundary conditions and the relationship between wavelength and wave velocity, the formula for the attenuation degree of the surface wave can be solved as follows:

[0089]

[0090]

[0091] In the formula, (C T is the shear wave velocity), (C L is the longitudinal wave velocity), λ s is the wavelength; it can be seen that the attenuation degree of the surface wave is inversely proportional to the wavelength of the surface wave. The smaller the wavelength, the faster the attenuation speed of the structural surface wave.

[0092] In step S3, based on the simulation calculation model of the equipment - pedestal - hull structure coupled vibration system and the initial ship equipment vibration damping structure based on waveform conversion and surface wave attenuation, a simulation calculation model of the equipment - surface wave vibration damping structure (i.e., the initial ship equipment vibration damping structure) - pedestal - hull structure is established to evaluate whether the vibration damping effect of the initial ship equipment vibration damping structure based on waveform conversion and surface wave attenuation meets the requirements of the equipment vibration damping index. If not, step S2 is iteratively executed to redesign the initial ship equipment vibration damping structure based on waveform conversion and surface wave attenuation until it meets the requirements, and the final ship equipment vibration damping structure based on waveform conversion and surface wave attenuation is obtained.

[0093] Furthermore, in an embodiment of the present invention, step S3 specifically includes:

[0094] Step S301, based on the initial ship equipment vibration damping structure based on waveform conversion and surface wave attenuation, on the basis of the simulation calculation model of the equipment - pedestal - hull structure coupled vibration system, establish a simulation calculation model of the equipment - surface wave vibration damping structure - pedestal - hull structure, and calculate and optimize the vibration characteristics of the system with the vibration acceleration level and the vibration level drop as the evaluation indexes of the vibration damping effect.

[0095] Specifically, during the modeling process, the simplification methods and steps of the equipment, the base, and the hull structure are the same as those in step S102. The hinge connection structure between adjacent sub-panel structures of the chain-type discrete panel of the initial ship equipment vibration damping structure can be simplified to a hinged unit, and the vibration isolation liquid layer can be simplified to an acoustic unit. On the basis of establishing the structural model, the corresponding material properties are assigned to the structural model, including necessary material parameters such as the density, damping, Young's modulus, and Poisson's ratio of the structural material, to ensure that the material information of the established model is consistent with the actual structure. The boundary conditions are set according to the actual application situation. According to the requirements of the calculation frequency band, the finite element model is meshed to ensure that the meshed model has sufficient calculation accuracy and high calculation efficiency.

[0096] Step S302: Compare the optimized system vibration characteristics with the equipment vibration damping index requirements and the system vibration damping design requirements to obtain the vibration damping effect of the initial ship equipment vibration damping structure based on waveform conversion and surface wave attenuation.

[0097] Specifically, the selection of the assessment points is the same as that in step S104; according to the calculated vibration acceleration level and vibration level drop, compare with the system vibration damping design requirements and the equipment vibration damping index requirements in step S104 to evaluate the vibration damping effect of the initial ship equipment vibration damping structure.

[0098] Step S303: Judge whether the vibration damping effect meets the preset vibration damping requirements. If it does not meet the vibration damping requirements, iterate and execute step S2 to redesign the initial ship equipment vibration damping structure based on waveform conversion and surface wave attenuation until it meets the requirements, and obtain the final ship equipment vibration damping structure based on waveform conversion and surface wave attenuation.

[0099] As Figure 7 shown, the spectrogram is the vibration acceleration response of the vibration isolation and damping system obtained by numerical simulation calculation using finite element software. The acceleration response spectrum curves of uniformly distributed reference points are extracted and averaged, and the average vibration acceleration level is calculated through the acceleration level formula to obtain the spectrogram of the comparison of the average vibration responses before and after the traditional vibration damping base and the surface wave vibration damping structure. It can be seen from Figure 7 this that the number of peak frequency points of the vibration acceleration response of the improved impedance homogenized base is significantly reduced, and the peak value is significantly reduced, and the vibration isolation and damping effect is obvious in the low frequency band.

[0100] It should be noted that the foregoing explanation of the embodiment of the ship equipment vibration damping structure based on waveform conversion and surface wave attenuation also applies to the method of this embodiment, and will not be elaborated here.

[0101] The ship equipment vibration reduction method based on waveform conversion and surface wave attenuation proposed according to the embodiments of the present invention has the following beneficial effects: (1) Utilizing the characteristic that elastic waves will undergo waveform conversion in different media, by adding a liquid isolation layer to the vibration reduction structure, the vibration waves transmitted to the vibration reduction structure are forced to undergo waveform conversion, converting the flexural waves propagating in the solid into longitudinal waves in the liquid, effectively reducing the transmission of vibration energy; (2) Utilizing the principle that the wave energy is mainly concentrated on the liquid surface and attenuates with the depth from the surface, by reasonably dividing and discretizing the panel structure arranged on the surface of the isolation liquid layer to construct a surface wave environment, effectively enhancing the dissipation of vibration energy; (3) Breaking through the limitation of the natural frequency ratio in the design of traditional vibration reduction structures, compared with the limitations of large mass or insufficient stability that may be brought about by the traditional passive vibration isolation and reduction design method when further improving the low-frequency vibration isolation and reduction level of the structure, it has a lightweight and more efficient vibration reduction effect; (4) It has high versatility, good practicability and a wide range of application fields, facilitating the popularization of technology.

[0102] To implement the above embodiments, the present invention also proposes a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the ship equipment vibration reduction method based on waveform conversion and surface wave attenuation as described in the foregoing embodiments.

[0103] To implement the above embodiments, the present invention also proposes a non-temporary computer-readable storage medium, on which a computer program is stored. When the computer program is executed by the processor, it implements the ship equipment vibration reduction method based on waveform conversion and surface wave attenuation as described in the foregoing embodiments.

[0104] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or N embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0105] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0106] Any process or method description represented in a flowchart or otherwise described herein can be understood to represent a module, segment, or portion of code including one or more N executable instructions for implementing a customized logical function or process. The scope of the preferred embodiments of the present invention includes additional implementations where functions may be executed in a substantially simultaneous manner or in the reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

[0107] The logic and / or steps represented in a flowchart or otherwise described herein, for example, can be considered a sequenced list of executable instructions for implementing a logical function, and can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection portion having one or more N wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or otherwise appropriate processing if necessary, and then stored in a computer memory.

[0108] It should be understood that various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above embodiments, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one of the following techniques well known in the art or a combination thereof can be used: discrete logic circuits having logic gate circuits for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0109] Those of ordinary skill in the art can understand that all or part of the steps carried by the method of the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0110] In addition, in each embodiment of the present invention, the functional units can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the above integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0111] The above-mentioned storage medium can be a read-only memory, a magnetic disk or an optical disc, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A vibration damping method for ship equipment based on waveform conversion and surface wave attenuation, characterized in that, It includes the following steps: Step S1: According to the preset types of ship mechanical equipment, layout drawings and structure drawings, establish a simulation calculation model of the equipment-base-hull structure coupled vibration system to determine the vibration reduction design requirements of the system; Step S2: Design an initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation according to the vibration reduction design requirements of the system; Step S3: Establish a simulation calculation model of the equipment-surface wave vibration reduction structure-base-hull structure based on the simulation calculation model of the equipment-base-hull structure coupled vibration system and the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation, and evaluate whether the vibration reduction effect of the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation meets the equipment vibration reduction index requirements. If not, iterate and execute Step S2 to redesign the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation until it meets the requirements, and obtain the final ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation.

2. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 1, characterized in that, The specific content of Step S1 includes: Step S101: Determine the equipment vibration reduction index requirements according to the preset types of ship mechanical equipment; Step S102: Establish the simulation calculation model of the equipment-base-hull structure coupled vibration system according to the preset layout drawings and structure drawings; Step S103: Take the vibration acceleration level and vibration level drop as the vibration reduction effect evaluation indexes, and use numerical methods to calculate the initial system vibration characteristics of the simulation calculation model of the equipment-base-hull structure coupled vibration system; Step S104: Compare the initial system vibration characteristics with the preset indexes to determine the vibration reduction design requirements of the system.

3. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 1, characterized in that, The specific content of Step S2 includes: Step S201: Determine the equipment mass and momentum characteristics during operation according to the preset types of ship mechanical equipment, layout drawings and structure drawings and the vibration reduction design requirements of the system, and then determine the stiffness requirements of the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation; Step S202: Determine the equipment foot position and excitation characteristics according to the preset types of ship mechanical equipment, layout drawings and structure drawings and the vibration reduction design requirements of the system, and then determine the number of sub-panels and arrangement positions of the chain discrete panel; Step S203: Determine the coverage range and number of liquid sacs of the vibration isolation liquid layer according to the arrangement position of the chain discrete panel, and determine the thickness of the vibration isolation liquid layer according to the vibration reduction design requirements and surface wave attenuation characteristics; Step S204: Determine the size of the limit box structure according to the coverage range and thickness of the vibration isolation liquid layer; Step S205: Determine the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation according to the stiffness requirements, the number of sub-panels and arrangement positions of the chain discrete panel, the coverage range of the vibration isolation liquid layer, the number and thickness of liquid sacs, and the size of the limit box structure.

4. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 3, characterized in that, The initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation includes: a chain discrete panel, a vibration isolation liquid layer and a limit box structure, where the chain discrete panel is arranged on the surface of the vibration isolation liquid layer, and the top of the chain discrete panel has a support end surface connected to the equipment; The vibration isolation liquid layer is arranged in the limit box-shaped structure; The bottom of the limit box-shaped structure is connected to the base panel or the raft structure by bolts.

5. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 4, characterized in that, The chain-type discrete panel includes a sub-panel structure and a hinge connection structure. Among them, there is a gap between adjacent sub-panel structures, and the adjacent sub-panel structures are connected by the hinge connection structure.

6. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 4, characterized in that, The vibration isolation liquid layer includes a plurality of liquid sacs, and each liquid sac includes a hyperelastic material sac body and the contained liquid.

7. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 4, characterized in that, The limit box-shaped structure is an open box-shaped structure, with a height lower than the thickness of the vibration isolation liquid layer and having no direct contact with the chain-type discrete panel.

8. The vibration damping method for ship equipment based on waveform conversion and surface wave attenuation according to claim 1, characterized in that, The specific steps of step S3 include: Step S301: Based on the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation, on the basis of the simulation calculation model of the equipment-base-hull structure coupling vibration system, establish a simulation calculation model of the equipment-surface wave vibration reduction structure-base-hull structure, and use the vibration acceleration level and the vibration level drop as the vibration reduction effect evaluation indexes to calculate and optimize the vibration characteristics of the system; Step S302: Compare the optimized system vibration characteristics with the equipment vibration reduction index requirements and the system vibration reduction design requirements to obtain the vibration reduction effect of the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation; Step S303: Judge whether the vibration reduction effect meets the preset vibration reduction requirements. If it does not meet the vibration reduction requirements, iterate and execute step S2 to redesign the initial ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation until it is satisfied, and obtain the final ship equipment vibration reduction structure based on waveform conversion and surface wave attenuation.

9. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the ship equipment vibration reduction method based on waveform conversion and surface wave attenuation as described in any one of claims 1-8.

10. A non-transitory computer-readable storage medium, on which a computer program is stored, characterized in that, When the computer program is executed by the processor, it implements the ship equipment vibration reduction method based on waveform conversion and surface wave attenuation as described in any one of claims 1-8.

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