A ship equipment base and optimization design method based on impedance uniformity

Abstract

The present invention relates to the field of hull vibration isolation technology, and specifically to a ship equipment base based on impedance equalization and an optimization design method. The optimization design method determines the base object for vibration reduction and isolation design based on the common base types of ship machinery and equipment; determines the specific requirements for base vibration reduction and isolation based on equipment information and excitation load characteristics; constructs a vibration reduction and isolation evaluation finite element model based on the equipment base layout and structural form, and evaluates the base vibration reduction and isolation effect using the base impedance equalization coefficient and vibration level difference as evaluation indicators; and determines the equipment base improvement plan from the perspective of impedance equalization, and performs base parameter optimization design; establishes an improved vibration reduction and isolation system model based on the determined impedance equalization base parameters, and evaluates the optimized base vibration reduction and isolation effect. The present invention carries out base vibration reduction and isolation design from the perspective of impedance equalization, improves the traditional base vibration reduction and isolation level and low-frequency vibration isolation effect, and enhances the stability of equipment operation.

Description

Technical Field

[0001] The present invention relates to the technical field of ship hull vibration isolation, and in particular to a ship equipment base based on impedance homogenization and an optimization design method. Background Art

[0002] Vibration-induced structure-borne noise from shipboard machinery is transmitted outward as elastic waves through the primary transmission path from the base to the hull and back to the flow field, impacting the overall ship's radiated noise level. Controlling structure-borne noise from shipboard machinery is primarily achieved through vibration isolation devices such as bases, dampers, and isolators. As the primary pathway for transmitting vibration-induced structure-borne noise from equipment outward from the hull, effective vibration isolation design for the base is crucial for controlling mechanical noise.

[0003] In the traditional vibration isolation system design process, after obtaining the intrinsic characteristics of the equipment, the mechanical equipment vibration isolation device is designed and improved according to the control frequency band of each physical parameter to achieve a better vibration isolation effect. However, when the excitation frequency is too low, low-frequency vibration isolation can only be achieved by reducing the stiffness of the system or increasing the mass of the vibration isolation body. However, this means that the elastic elements of the isolation system require greater static deformation and system mass, which is detrimental to the stability of the vibration isolation system and the lightweighting of the ship. Therefore, new solutions are needed for low-frequency and even lower-frequency vibration isolation.

[0004] A search revealed a vibration reduction design method for mechanical equipment in Chinese patent document CN112861281A. This method primarily combines the parameter selection and design of the vibration reduction device with the equipment itself. Modal analysis and static structural analysis are used to determine the vibration mode, natural frequency, and maximum static displacement of the vibration reduction device. The vibration mode is then evaluated and the vibration reduction efficiency is calculated based on the ambient vibration conditions. Ultimately, a vibration reduction device is designed to meet the vibration mode, vibration reduction efficiency, and maximum static displacement requirements. However, this vibration reduction design method only considers vibration reduction within the system mode, which has certain limitations.

[0005] For another example, Chinese patent document CN106114797A discloses a double-layer vibration damping device for a full-rotation propeller and its design method. The double-layer vibration damping device can effectively damp the vertical, lateral, longitudinal, torsional directions and coupled vibrations of the full-rotation propeller device at the same time. Multiple vibration damping blocks are evenly arranged along the four sides of the mounting platform and divided into upper and lower layers, which can effectively control the deformation of the vibration damping blocks caused by the input shaft torque and propeller thrust at the same time, reducing the dynamic deformation problem of the input shaft of the propeller device and reducing the vibration transmitted from the propeller device to the stern structure, thereby improving operational stability. However, its design method calculates the number of vibration damping blocks in parallel and the stiffness of a single vibration damping block based on the total stiffness and the required vibration damping effect. The vibration isolation form is single and the lightweight is insufficient.

[0006] In summary, in the process of implementing vibration isolation optimization for marine equipment, how to design an optimization method to improve the impedance uniformity of the vibration isolation device, improve the vibration isolation performance, and form an effective evaluation of the vibration isolation effect has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0007] The purpose of the present invention is to provide an optimization method for improving the impedance uniformity of the vibration isolation device, improving the vibration isolation performance, and forming an effective evaluation of the vibration isolation effect during the process of implementing vibration isolation optimization for ship equipment.

[0008] To achieve the above-mentioned object, the present invention adopts the following scheme: a ship equipment base based on impedance equalization is proposed, comprising a spring limit device, a vibration isolation liquid layer structure and a panel;

[0009] One end of the spring limit device is connected to the hull structure, and the other end of the spring limit device is connected to the panel. The vibration isolation liquid layer structure is located between the panel and the hull structure. The top of the panel has a supporting end surface connected to the marine equipment.

[0010] The vibration isolation liquid layer structure includes a vibration isolation liquid bag. A plurality of vibration isolation liquid bags are arranged on the hull structure. The bag bodies of the vibration isolation liquid bags are respectively connected to the hull structure and the panel. The interior of the bag body has a buffer cavity for accommodating liquid.

[0011] Preferably, the panels on the vibration isolation bladder are constructed as multiple plates, with gaps between adjacent plates and connected by connecting structures. This arrangement creates a discontinuous plate structure, facilitating the rational discretization of the base panels and effectively isolating and controlling elastic waves within the panel response surface, thereby effectively improving the vibration reduction and isolation performance of the base.

[0012] Preferably, the plate-like structures are connected by hinges. In this arrangement, the hinges are used to further absorb elastic energy between the plate-like structures, thereby further improving the vibration reduction and isolation performance of the base.

[0013] The present invention also proposes an optimization design method for the ship equipment base based on impedance equalization, comprising:

[0014] Step S1: Determine the vibration reduction and isolation design foundation object, i.e., the first foundation structure, based on the commonly used foundation types of marine machinery and equipment;

[0015] Step S2: determining the specific vibration reduction and isolation requirements of the first base structure based on the ship machinery and equipment information and the excitation load characteristics;

[0016] Step S3: Based on the equipment foundation layout and structural form, a finite element model for vibration reduction and isolation evaluation of the "equipment-foundation-hull structure" is constructed, and the vibration reduction and isolation effect of the first foundation structure is evaluated using the foundation impedance uniformity coefficient and vibration level difference as evaluation indicators;

[0017] Step S4: Based on the vibration reduction and isolation requirements of different types of equipment, determine the equipment base improvement plan from the perspective of impedance uniformity and perform base parameter optimization design;

[0018] Step S5: establishing an improved vibration reduction and isolation system model based on the determined impedance homogenization base parameters, and evaluating the vibration reduction and isolation effect of the optimized base;

[0019] Step S6: Compare the vibration reduction and isolation effects of the impedance equalization base and the first base structure. If the vibration reduction and noise reduction goals are not achieved, return to step S4 and redesign until the expected design goals are met.

[0020] Preferably, the common foundation types for marine machinery and equipment in step S1 include small foundations that only provide support without vibration isolation requirements, foundations that require stable equipment operation, and foundations that require support height.

[0021] Preferably, the ship machinery equipment information in step S2 includes equipment weight and size, equipment installation status, equipment protection level and maximum allowable offset, and the excitation load characteristics include excitation load form and excitation load curve.

[0022] Preferably, step S3 further includes:

[0023] Step S31: Establish a vibration reduction and isolation evaluation structural model of "equipment-base-hull structure" in finite element simulation software according to the actual structural dimensions;

[0024] Step S32: assigning material properties to the structural model according to actual material information;

[0025] Step S33: setting the model boundary conditions according to the actual boundaries;

[0026] Step S34: Divide the finite element grid according to calculation requirements;

[0027] Step S35: Calculate the base impedance uniformity coefficient and vibration level difference according to the simulation calculation results;

[0028] The calculation formula of the base impedance uniformity coefficient is:

[0029]

[0030] Where m is the number of frequency points in the analysis band, V iTo calculate the coefficient of dispersion (also called coefficient of variation), which is defined as the ratio of the standard deviation of the data to its mean, ZDC is the discretization coefficient of the base impedance, defined as

[0031] The calculation formula for vibration level difference is:

[0032]

[0033] Where 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.

[0034] Preferably, step S4 further includes:

[0035] Step S41: Improve the original traditional single steel structure base form into a "chain panel-vibration isolation liquid layer-base base" composite structure form;

[0036] Step S42: Optimize the design of the base parameters, wherein the optimized parameters include: vibration isolation liquid layer structural characteristic parameters and base panel parameters. The vibration isolation liquid layer structural parameters include liquid density, liquid dynamic viscosity coefficient, liquid layer area and number of liquid capsules. The base panel parameters include base panel thickness, the ratio of the number of base panels to the number of machine feet.

[0037] Preferably, step S5 further includes:

[0038] Step S51: establishing an improved vibration reduction and isolation system model as an "equipment-base-hull structure" vibration reduction and isolation evaluation model in finite element simulation software;

[0039] Step S52: assigning material attributes to the structural model according to actual material information;

[0040] Step S53: setting the model boundary conditions according to the actual boundaries;

[0041] Step S54: Divide the finite element mesh according to calculation requirements;

[0042] Step S55: Calculate the base impedance uniformity coefficient and vibration level difference according to the simulation calculation results. The evaluation basis is that the larger the impedance uniformity coefficient and vibration level difference, the better the vibration reduction and isolation effect of the base.

[0043] Preferably, the comparative evaluation index of the vibration reduction and isolation effect of the impedance equalization base and the first base structure is the average vibration response of the vibration isolation system, and the expected design goal is the vibration reduction and noise reduction goal of actual ship application.

[0044] Compared with the prior art, the ship equipment foundation and optimization design method based on impedance equalization provided by the present invention have the following outstanding substantive features and significant improvements:

[0045] 1. This marine equipment base based on impedance homogenization uses a vibration isolation liquid sac to form a vibration isolation liquid layer structure between the hull structure and the marine equipment. The liquid in the sac acts as a liquid load to affect the vibration of the base panel. Part of the vibration energy will be dissipated in the form of waves through the fluid medium in contact with it. When the fluid impedance shows pure resistance, the action of the fluid medium will provide inertial force, effectively controlling low-frequency vibration energy. Combined with the physical properties of the liquid, the impedance of the entire base is uniformed, thereby improving the vibration reduction and isolation capability of the marine equipment base and enhancing the comfort and acoustic performance of the ship.

[0046] 2. This optimized design method for marine equipment foundations based on impedance homogenization conducts foundation vibration reduction and isolation design from the perspective of impedance homogenization. It uses liquid layer vibration isolation instead of traditional rigid vibration isolation design to isolate the transmission of vibration energy. Compared with the defect of traditional foundation design methods that the foundation input impedance is uneven in space, resulting in a weakened vibration isolation effect, this method effectively improves the foundation's vibration reduction and isolation level.

[0047] 3. This optimized design method for marine equipment foundations based on impedance homogenization achieves superior vibration isolation without adding additional equipment. This method is superior to traditional foundation design methods, which may cause foundation stability limitations by changing system mass, stiffness, and damping during low-frequency vibration isolation.

[0048] 4. The optimization design method of the ship equipment base based on impedance homogenization has high versatility. The design of the vibration isolation base can be quantitatively calculated and the vibration isolation effect can be effectively evaluated through the present invention. It has good practicality and a wide range of applications, which facilitates technology promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a structural diagram of a ship equipment base based on impedance equalization in an embodiment of the present invention;

[0050] Figure 2 yes Figure 1 A reference diagram of the use status of a ship equipment base based on impedance equalization;

[0051] Figure 3 is a flow chart of the optimization design method of the base in an embodiment of the present invention;

[0052] Figure 4 is a flow chart for obtaining the impedance equalization coefficient;

[0053] Figure 5 This is a comparison curve of the vibration isolation effects of the traditional base and the impedance equalization base.

[0054] Figure numerals: 1. Spring limit device; 2. Vibration isolation liquid layer structure; 3. Hull structure; 4. Panel; 5. Connection structure; 6. Marine equipment; 7. Vibration response peak point. DETAILED DESCRIPTION

[0055] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0056] Example 1

[0057] like Figure 1-2 The illustrated impedance-homogenized marine equipment base is used to improve the vibration isolation capability of the marine equipment base during vibration isolation optimization of the hull structure. This impedance-homogenized marine equipment base utilizes a vibration isolation liquid bladder to form a vibration isolation liquid layer between the hull structure and the marine equipment. The liquid within the bladder acts as a liquid load, affecting the vibration of the base panel. Some of the vibration energy is dissipated as waves through the fluid medium in contact with it. When the fluid impedance exhibits pure resistance, the fluid medium provides inertial force, effectively controlling low-frequency vibration energy. Combined with the physical properties of the liquid, the impedance of the entire base is homogenized, improving the vibration isolation capability of the marine equipment base and enhancing the comfort and acoustic performance of the ship.

[0058] like Figure 1 As shown, a ship equipment base based on impedance equalization includes a spring limit device 1, a vibration isolation liquid layer structure 2 and a panel 4. One end of the spring limit device 1 is connected to the hull structure 3. The other end of the spring limit device 1 is connected to the panel 4. The vibration isolation liquid layer structure 2 is located between the panel 4 and the hull structure 3. The top of the panel 4 has a supporting end surface connected to the ship equipment 6. The vibration isolation liquid layer structure 2 includes a vibration isolation liquid bag. A plurality of vibration isolation liquid bags are arranged on the hull structure 3. The bag body of the vibration isolation liquid bag is respectively connected to the hull structure 3 and the panel 4. The interior of the bag body has a buffer cavity for containing liquid.

[0059] The spring limiter 1 uses a piston-type molecular spring isolator. This configuration utilizes a molecular spring hybrid medium composed of water and a porous hydrophobic material. When pressure is applied to the molecular spring hybrid medium, water molecules enter the hydrophobic nanopores of the porous hydrophobic material. When the pressure is unloaded, the water molecules escape from the pores, storing and releasing energy, thereby eliminating vibration and further enhancing the vibration reduction and isolation performance of the base.

[0060] like Figure 2As shown, the panel 4 on the vibration isolation liquid bag is a multi-plate structure. There is a gap between adjacent plate structures. Adjacent plate structures are connected by a connecting structure 5. With this arrangement, the panel 4 presents a discontinuous plate structure, which is convenient for reasonably discretizing the base panel 4, and is beneficial for effectively isolating and controlling the elastic waves within the response surface of the panel 4, thereby effectively improving the vibration reduction and isolation performance of the base. For example, the plate structures are connected by hinges. With this arrangement, the hinges are used to further absorb the elastic energy between the plate structures, thereby further improving the vibration reduction and isolation performance of the base.

[0061] When the impedance-homogenized marine equipment base proposed in Example 1 of the present invention is used, the presence of the vibration-isolating liquid layer structure (vibration-isolating liquid sac) will make the input impedance at all locations on the base panel more uniform, avoiding large differences in input impedance calculations caused by structural reinforcement under the base panel. This keeps the impedance dispersion coefficient curve of the base at a low level, effectively reducing the vibration response under the equipment excitation force. At the same time, the improved uniformity of the base impedance will reduce the vibration aggravation caused by the unbalanced excitation force and torque acting on the base structure, and realize the transformation of the excitation from concentrated point load to surface load, thereby improving the system's vibration reduction and isolation capabilities.

[0062] Since there is no shear elasticity in the liquid medium, shear waves cannot propagate in the liquid medium. When the vibration energy caused by the operation of the equipment is transmitted to the hull structure in the form of waves, a sudden change of the medium occurs in the transmission path, causing impedance mismatch between the structures and forced wave conversion. At this time, part of the vibration energy caused by the equipment will be limited above the vibration isolation liquid layer, and the vibration elastic wave cannot continue to be transmitted to the underlying structure, thereby playing a good isolation role for the vibration wave and improving the vibration isolation performance of the base.

[0063] Under the influence of the equipment's gravity, the discontinuous base panel will come into close contact with the vibration isolation sac. The liquid in the sac will act as a liquid load, affecting the vibration of the base panel. Some of the vibration energy will be dissipated as waves through the fluid medium in contact with it. When the fluid impedance exhibits pure resistance, the fluid medium will provide inertial force, effectively controlling low-frequency vibration energy. The discontinuous base panel is a rational discretization of the base panel, which can effectively isolate and control elastic waves within the panel's response surface, thereby effectively improving the base's vibration reduction and isolation capabilities.

[0064] Example 2

[0065] like Figure 3-4 The optimized design method of a ship equipment base based on impedance equalization shown in the figure includes the following steps:

[0066] Step S1: Determine the vibration reduction and isolation design foundation object based on the common foundation types of marine machinery and equipment;

[0067] Specifically, for small bases that provide support but do not require vibration isolation, their structures are simple and their functions are relatively single, so the original structural form can be retained without modification. For equipment bases that require vibration isolation, an impedance equalization base design is carried out based on the traditional vibration reduction and isolation design (such as adding reinforcing components such as elbow plates).

[0068] Step S2: Determine the specific requirements for base vibration reduction and isolation based on the ship's mechanical equipment information and excitation load characteristics.

[0069] Specifically, in step S21, according to the device type, basic information of the device is clarified, including but not limited to the weight and size of the device, the installation status of the device, the protection level of the device, and the maximum allowable offset;

[0070] Step S22: Determine the characteristics of the equipment excitation load, including but not limited to the excitation load form and excitation load curve. Excitation load forms include unbalanced excitation force, unbalanced excitation torque, and the combined effect of unbalanced excitation force and torque. The excitation load curve includes the equipment excitation frequency distribution and excitation response peak information, so as to facilitate targeted control measures during the base vibration reduction and isolation design.

[0071] Step S3: Based on the equipment foundation layout and structural form, a finite element model of "equipment-foundation-hull structure" vibration reduction and isolation evaluation is constructed, and the vibration reduction and isolation effect of a certain type of foundation is evaluated using the foundation impedance uniformity coefficient as an evaluation index;

[0072] like Figure 4 As shown:

[0073] Step S31: Based on the equipment foundation structure and layout information, a finite element structural model of the "equipment-foundation-hull structure" vibration reduction and isolation evaluation is established in the finite element simulation software ABAQUS. The model includes a simplified equipment model, a vibration isolation system model including the foundation and raft, a hull structure model, and a vibration and acoustic radiation system evaluation model, ensuring that the structural form and size of the established model are consistent with the actual structure;

[0074] The device model can be replaced by a cube of equal mass. The simplified model must maintain the same total mass as the original model and a consistent mass distribution. The model can be truncated appropriately based on computational efficiency requirements.

[0075] Step S32: assigning corresponding material property parameters to the established structural model in the finite element simulation software ABAQUS, including necessary material parameters such as structural material density, damping, Young's modulus, and Poisson's ratio, to ensure that the established model material information is consistent with the actual structure;

[0076] Step S33, setting boundary conditions in the established finite element model to ensure that the boundary conditions of the established model are consistent with the boundary conditions in actual application;

[0077] Step S34, meshing the finite element model according to calculation requirements to ensure that the meshed model has sufficient calculation accuracy;

[0078] Step S35: numerically calculate the input impedance and transfer impedance of the current form of the base, and on this basis calculate parameter indicators such as the impedance uniformity coefficient and the vibration level drop.

[0079] The specific method is: select evenly distributed reference points on the base panel structure as excitation points and response pickup points. The selection of reference points should be based on the actual structural dimensions of the base panel and should ensure that they are evenly distributed on all parts of the base panel. The number of reference points can usually be 4-8. The ratio of the excitation force to the vibration response of the excitation point is the input impedance, which is calculated as follows:

[0080]

[0081] Where, F i is the generalized excitation force of the excitation point, X i is the generalized vibration response at the excitation point.

[0082] The ratio of the excitation force to the vibration response of the non-excitation point is the transfer impedance, which is calculated as follows:

[0083]

[0084] Where, X j is the generalized vibration response at the non-excitation point.

[0085] Among them, the specific calculation method of the base impedance uniformity coefficient is:

[0086] Select n loading points evenly on the surface of the base structure. Each loading point has an input impedance Z0i(f) at the frequency f. The n loading points on the base have a standard deviation S at the frequency i. i ,writing:

[0087]

[0088] Where, It represents the average input impedance of each loading point at frequency i.

[0089] The ratio of the standard deviation of the data to its mean is defined to calculate the coefficient of variation V i :

[0090]

[0091] The impedance standard deviation curve and dispersion coefficient curve at each frequency point in the required frequency band are averaged to obtain the base impedance discretization coefficient ZDC:

[0092]

[0093] Where m is the number of frequency points in the analysis band.

[0094] The derivative of the base impedance discretization coefficient is the impedance uniformity coefficient ZSC:

[0095]

[0096] The calculation formula for vibration level difference is:

[0097]

[0098] Where 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.

[0099] Step S4: Based on the vibration reduction and isolation requirements of different types of equipment, determine an improvement plan for equipment base impedance uniformity from the perspective of impedance uniformity, and perform optimal design of base parameters;

[0100] Specifically:

[0101] Step S41: Based on the original model, the original traditional single steel structure foundation is improved into a composite structure of "chain panel-vibration isolation liquid layer-foundation base";

[0102] Step S42: Optimize the design of the base parameters. The optimized parameters include but are not limited to: vibration isolation liquid layer characteristic parameters and base panel parameters. Specifically, the vibration isolation liquid layer parameters include liquid density, liquid dynamic viscosity coefficient, liquid layer area, and the number of liquid capsules. The base panel parameters include base panel thickness and the ratio of the number of base panels to the number of machine feet.

[0103] As an example, Figure 1 Combine Figure 2As shown, the vibration isolation base is used for vertical vibration reduction of marine equipment 6, and includes a spring limiter 1, a vibration isolation liquid layer structure 2, a hull structure 3, a base panel 4, and a connection structure 5. The impedance equalization base design mainly includes the design of the vibration isolation liquid layer structure 2 and the design of the base panel 4; the marine equipment 6 includes but is not limited to air compressors, pump controllers, motors and other large, medium and small equipment with vibration isolation requirements; the spring limiter 1 includes but is not limited to various types of limiters that serve as elastic supports; the liquid in the vibration isolation liquid layer structure 2 includes but is not limited to Newtonian and non-Newtonian liquids such as water and oil; the hull structure 3 includes but is not limited to bottom support structures such as decks and rafts; the number of base panels 4 includes but is not limited to the number shown in the figure, and is selected according to the vibration isolation design requirements; the panel connection structure 5 includes but is not limited to hinge structures, latch structures, and other mechanisms and structures that serve to connect two adjacent panels.

[0104] Step S5: establishing an improved vibration reduction and isolation system model based on the determined impedance homogenization base parameters, and evaluating the vibration reduction and isolation effect of the optimized base;

[0105] Specifically:

[0106] Step S51: In the finite element software ABAQUS, based on the original model, a vibration reduction and isolation system evaluation model of "base panel-vibration isolation liquid layer-hull structure" is established using the finite element method. The model includes a simplified equipment model, a base panel model, a vibration isolation liquid layer model, a raft and hull structure model, and a vibration and acoustic radiation system evaluation model, ensuring that the structural form and size of the established model are consistent with the actual structure;

[0107] The panel connection structure and the limit structure can be replaced by spring connections. Contact is set between the base panel and the vibration isolation liquid layer, and between the vibration isolation liquid layer and the base structure. The simplified model must maintain the same total mass as the original model and the mass distribution is consistent.

[0108] Step S52: assign corresponding material property parameters to the established structural model in the finite element simulation software ABAQUS, and assign liquid properties to the established vibration isolation liquid layer model, including necessary liquid property parameters such as liquid density and viscosity coefficient, to ensure that the established model material information is consistent with the actual situation;

[0109] Step S53: setting boundary conditions in the established finite element model, ensuring that the boundary conditions of the established model are consistent with the boundary conditions in actual application;

[0110] Step S54: meshing the finite element model according to calculation requirements to ensure that the meshed model has sufficient calculation accuracy;

[0111] Step S55: Numerical methods are used to calculate the input impedance and transfer impedance of the improved impedance equalization base. Based on this, parameters such as the impedance equalization coefficient and vibration level drop are calculated. A higher value for this parameter indicates a better vibration reduction and isolation effect of the base. The calculation method for these parameters is the same as in step S35.

[0112] Step S6: Using the average vibration response of the vibration isolation system as the evaluation index, compare the vibration reduction and isolation effects of the improved impedance equalization base with those of the original base. If the expected design goal is achieved, the vibration reduction design process of the base based on impedance equalization is completed. If the expected design goal is not achieved, return to step S4, redesign the characteristic parameters of the "base panel-vibration isolation liquid layer-hull structure" vibration reduction and isolation system, and perform calculation and evaluation until the expected design goal is met.

[0113] As an example of comparing the average vibration response, the dimensions of the traditional base are: base panel 1.8m×1.0m, thickness 0.02m, total base height 0.17m, number of base axis plates 6, 3 evenly distributed on each side, thickness 0.01m, and base material Q235 steel; the dimensions of the improved impedance uniformization base are: number of discontinuous base panels 3, single panel size 0.6m×1.0m, thickness 0.02m, vibration isolation liquid layer thickness 0.12m, and the liquid is water.

[0114] like Figure 5 As shown in the figure, the spectrum is the vibration acceleration response of the vibration reduction and isolation system obtained by numerical simulation calculation using the finite element software ABAQUS. The acceleration response spectrum curve of the uniformly distributed reference points is extracted and averaged, and the average vibration acceleration level is calculated using the acceleration level formula. The spectrum of the average vibration response comparison before and after the base improvement is obtained. Figure 5 It can be seen from the figure that the number of peak frequency points 7 of the vibration acceleration response of the improved impedance uniformization base is significantly reduced, and the peak value is significantly reduced, and the vibration reduction and isolation effect is obvious in the low frequency band.

[0115] The present invention is not limited to the specific technical solutions described in the above embodiments. In addition to the above embodiments, the present invention may also have other implementation methods. For those skilled in the art, any technical solutions formed by modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An optimization design method for ship equipment base based on impedance equalization, characterized in that The following steps are involved: Step S1: Determine the vibration reduction and isolation design foundation object, i.e., the first foundation structure, based on the commonly used foundation types of marine machinery and equipment; Step S2: determining the specific vibration reduction and isolation requirements of the first base structure based on the ship machinery and equipment information and the excitation load characteristics; Step S3: Based on the equipment foundation layout and structural form, a finite element model for vibration reduction and isolation evaluation of the "equipment-foundation-hull structure" is constructed. The vibration reduction and isolation effect of the first foundation structure is evaluated using the foundation impedance uniformity coefficient and vibration level difference as evaluation indicators. Step S4: Based on the vibration reduction and isolation requirements of different types of equipment, determine the equipment base improvement plan from the perspective of impedance uniformity and perform base parameter optimization design; Step S5: establishing an improved vibration reduction and isolation system model based on the determined impedance homogenization base parameters, and evaluating the vibration reduction and isolation effect of the optimized base; Step S6: Compare the vibration reduction and isolation effects of the impedance equalization base and the first base structure. If the vibration reduction and noise reduction goals are not achieved, return to step S4 and redesign until the expected design goals are met. Wherein, the ship equipment base based on impedance equalization includes a spring limit device, a vibration isolation liquid layer structure and a panel; One end of the spring limit device is connected to the hull structure, and the other end of the spring limit device is connected to the panel. The vibration isolation liquid layer structure is located between the panel and the hull structure. The top of the panel has a supporting end surface connected to the marine equipment. The vibration isolation liquid layer structure includes a vibration isolation liquid bag. A plurality of vibration isolation liquid bags are arranged on the hull structure. The bag bodies of the vibration isolation liquid bags are respectively connected to the hull structure and the panel. The interior of the bag body has a buffer cavity for accommodating liquid.

2. The optimization design method of a ship equipment foundation based on impedance equalization according to claim 1, characterized in that: Common types of foundations for marine machinery and equipment in step S1 include small foundations that only provide support without vibration isolation requirements, foundations that require stable equipment operation, and foundations that require support height.

3. The optimization design method of a ship equipment foundation based on impedance equalization according to claim 1, characterized in that: The ship machinery equipment information in step S2 includes equipment weight and size, equipment installation status, equipment protection level and maximum allowable offset, and the excitation load characteristics include excitation load form and excitation load curve.

4. The optimization design method of a ship equipment foundation based on impedance equalization according to claim 1, characterized in that: The step S3 comprises: Step S31: Establish a vibration reduction and isolation evaluation structural model of "equipment-base-hull structure" in finite element simulation software according to the actual structural dimensions; Step S32: assigning material properties to the structural model according to actual material information; Step S33: setting the model boundary conditions according to the actual boundaries; Step S34: Divide the finite element grid according to calculation requirements; Step S35: Calculate the base impedance uniformity coefficient and vibration level difference according to the simulation calculation results; The calculation formula of the base impedance uniformity coefficient is: Where m is the number of frequency points in the analysis band, V i To calculate the coefficient of dispersion (also called coefficient of variation), which is defined as the ratio of the standard deviation of the data to its mean, ZDC is the discretization coefficient of the base impedance, defined as The vibration level difference calculation formula is: Where 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.

5. The optimization design method of a ship equipment foundation based on impedance equalization according to claim 1, characterized in that: The step S4 comprises: Step S41: Improve the original traditional single steel structure base form into a "chain panel-vibration isolation liquid layer-base base" composite structure form; Step S42: Optimize the design of the base parameters, including: vibration isolation liquid layer structural characteristic parameters and base panel parameters. The vibration isolation liquid layer structural parameters include liquid density, liquid dynamic viscosity coefficient, liquid layer area and number of liquid capsules. The base panel parameters include base panel thickness, the ratio of the number of base panels to the number of machine feet.

6. The optimization design method of a ship equipment foundation based on impedance equalization according to claim 1, characterized in that: The step S5 comprises: Step S51: Establishing an improved vibration reduction and isolation system model as an "equipment-base-hull structure" vibration reduction and isolation evaluation model in finite element simulation software; Step S52: assigning material attributes to the structural model according to actual material information; Step S53: setting the model boundary conditions according to the actual boundaries; Step S54: Divide the finite element mesh according to calculation requirements; Step S55: Calculate the base impedance uniformity coefficient and vibration level difference according to the simulation calculation results. The evaluation basis is that the larger the impedance uniformity coefficient and vibration level difference, the better the vibration reduction and isolation effect of the base.

7. The optimization design method for a ship equipment foundation based on impedance equalization according to claim 1, characterized in that: The comparative evaluation index of the vibration reduction and isolation effects of the impedance homogenization base and the first base structure is the average vibration response of the vibration isolation system, and the expected design goal is the vibration reduction and noise reduction goal of actual ship application.

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