Low-frequency impedance design method and system for pipeline structures in underwater vehicles

Abstract

The present invention belongs to the field of vibration and noise control technology, and discloses a low-frequency impedance design method and system for a pipeline structure in an underwater vehicle. The low-frequency impedance design method for a pipeline structure in an underwater vehicle provided by the present invention includes the following steps: establishing a simplified mathematical model for impedance calculation for different pipeline systems; establishing a vibration equation for the mathematical model, solving its origin response, and then obtaining an impedance solution; generating a program to complete a rapid impedance prediction. A method for rapid estimation of low-frequency impedance of typical pipeline structures in underwater vehicles, including seagoing pipelines, cabin pipelines, and supports and hangers. Based on the impedance method, the present invention establishes a mathematical model for impedance calculation of different pipeline and shell coupling structures, studies the effect of the pipeline structure on the underwater vehicle in the low-frequency band, simplifies the effect into a force or bending moment applied to the shell, and obtains its impedance theoretical solution by analyzing the vibration characteristics of the shell structure, thereby realizing a rapid prediction of impedance.

Description

Technical Field

[0001] The present invention belongs to the technical field of vibration and noise control, and in particular relates to a method and system for designing low-frequency impedance of a pipeline structure in an underwater vehicle. Background Art

[0002] The structural vibration generated by the operation of mechanical equipment inside the ship is transmitted to the hull through the foundation, pipelines and other channels. The mechanical impedance method is widely used in the analysis of structural dynamic characteristics and acoustic vibration transmission laws. As one of the important design parameters, the input mechanical impedance of the ship foundation determines the proportion of vibration energy input from the excitation source to the hull structure. Using the physical mechanism of impedance mismatch between the components of the piping system to control vibration transmission is an effective technical approach to vibration control. Related research has established a method for estimating effective impedance related to the foundation, but has not yet established a complete impedance analysis mechanism for the piping system.

[0003] At present, impedance is usually obtained by building a finite element model or experimental testing. However, when the ship structure model is large, the finite element calculation takes a long time and has low calculation efficiency. The experimental measurement points are inconvenient to arrange and cannot be used as a reference in the early stage of ship design. Therefore, based on the impedance method, this paper intends to use a method that combines theoretical derivation and finite element simulation analysis to quickly predict the impedance of the pipeline and shell coupling structure.

[0004] Through the above analysis, the problems and defects of the prior art are as follows:

[0005] The existing impedance is usually obtained by establishing a finite element model or experimental testing. When the ship structure model is large, the finite element calculation takes a long time and has low calculation efficiency. The experimental measurement points are inconvenient to arrange and cannot be used as a reference in the early stage of ship design. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for designing the low-frequency impedance of a pipeline structure in an underwater vehicle.

[0007] The present invention conducts a comprehensive analysis on the vibration characteristics of typical piping systems (including seagoing pipelines, through-cabin pipelines and supports and hangers), abstracts them into simple systems under the action of concentrated forces, and lists motion equations based on the force characteristics. The origin impedance is obtained by solving the motion equations, and the cross-point impedance is obtained by approximation or electroacoustic analogy. The low-frequency impedance prediction of underwater vehicles is achieved through finite element simulation and comparison.

[0008] The present invention provides a low-frequency impedance design method for a pipeline structure in an underwater vehicle, the method comprising the following steps:

[0009] 1. According to the actual structure and size of the pipeline system in the underwater vehicle, a simplified mathematical model for impedance calculation is established, which can reflect the vibration characteristics of the pipeline system under stress;

[0010] 2. On the basis of simplified mathematical model, establish the vibration equation, and obtain the origin response of the piping system by solving the equation;

[0011] 3. Based on the origin response, the impedance solution of the pipeline system is calculated, and the cross-point impedance is obtained by approximation or electroacoustic analogy method;

[0012] 4. Write a program that can automatically generate the data and parameters required for impedance calculation and quickly complete impedance prediction to provide data support for the design and optimization of underwater vehicles.

[0013] The present invention provides a low-frequency impedance design system for underwater vehicles and pipeline structures in marine engineering, the system comprising:

[0014] 1. A data input module, used to receive actual structure and size data about the piping system;

[0015] 2. Model building module, which automatically builds a simplified mathematical model for impedance calculation based on the received data;

[0016] 3. Vibration analysis module, which performs vibration analysis on the established mathematical model, establishes and solves the vibration equation, and obtains the origin response of the piping system;

[0017] 4. Impedance calculation module, which calculates the impedance solution of the pipeline system based on the origin response and obtains the cross-point impedance using approximate or electroacoustic analogy methods;

[0018] 5. The prediction output module automatically generates impedance prediction data through the program and outputs it in the form of visualization or data report to provide decision support for the design and optimization of pipeline structure.

[0019] The present invention provides a method for designing low-frequency impedance of a pipeline structure in an underwater vehicle, comprising:

[0020] Step 1: Establish a simplified mathematical model for impedance calculation for different pipeline systems;

[0021] Step 2: Establish the vibration equation of the mathematical model, solve its origin response, and then obtain the impedance solution;

[0022] Step three, generate a program to complete the impedance rapid prediction.

[0023] Furthermore, the method for establishing a simplified mathematical model for impedance calculation is as follows:

[0024] (1) Low-frequency impedance prediction of sea-going pipelines;

[0025] (2) Low-frequency impedance prediction of supports and hangers;

[0026] (3) Prediction of low-frequency impedance of pipelines through the cabin.

[0027] Furthermore, the low-frequency impedance prediction of the sea-going pipeline is:

[0028] The expression of compartment ring frequency is as follows:

[0029]

[0030] In the formula, C l is the longitudinal wave velocity of a plate with the same thickness as the cylindrical shell, R, E and υ are the radius, thickness, Young's modulus and Poisson's ratio of the cylindrical shell, respectively;

[0031] The differential equation of motion of a cylindrical shell can be expressed as:

[0032]

[0033] Where h is the thickness of the cylindrical shell; [L ij ] is the shell differential operator, {U}={u,v,w} T represents the axial, circumferential and radial displacements of the shell, {F} is the excitation force acting on the shell, and {q} = {0,0,q r} is the sound pressure of the external fluid acting on the shell surface;

[0034] Assume that N acts on the shell F point excitation, where the kth excitation axial and circumferential excitation is (x k ,θ k ), then the excitation force vector {F} is:

[0035]

[0036] Among them, F kx 、F kθ 、F kr 、M kx 、M kθ and M kxθ To act on (x k ,θ k ) out of the axial force, circumferential force, radial force, axial moment, circumferential moment and radial moment; δ is the Dirac function;

[0037] When both ends of the cylindrical shell are simply supported boundaries, the displacement function can be expressed as:

[0038]

[0039]

[0040]

[0041] In the formula, k m =mπ / L, α=1 (or 0) represents the symmetric mode (antisymmetric mode), m and n represent the axial half-wave number and the circumferential wave number respectively;

[0042] The radiated sound pressure of a finite length cylindrical shell simply supported at both ends on a rigid cylindrical baffle can be expressed as:

[0043]

[0044] In the formula,

[0045]

[0046] Where k0 = ω / c0, Therefore, the sound pressure {q} of the fluid acting on the single-layer cylindrical shell is ir for:

[0047] q r =p(R,θ,x) (7)

[0048] Substituting equations (3)-(7) into equation (2) and applying the orthogonality of trigonometric functions, both the symmetric mode and the antisymmetric mode can obtain a system of m×n×3 independent equations. Solving this system of equations can obtain all the displacement terms {U αmn ,V αmn ,W αmn} T ;

[0049] After obtaining the displacement response, the origin impedance of the cylindrical shell can be obtained by solving the following equation:

[0050]

[0051] Furthermore, the low-frequency impedance prediction of the support and hanger is:

[0052] The impedance at the mass point is: Z1 = jωm, and the impedance at the spring is: Z3 is the origin impedance of the support and hanger rooting position;

[0053] The origin impedance of the support bracket is

[0054]

[0055] The span impedance at the support bracket position is

[0056]

[0057] Furthermore, the low-frequency impedance prediction of the through-tank pipeline is:

[0058] The differential equation of motion of the circular plate / annular plate is

[0059]

[0060]

[0061]

[0062] In the formula, is the plate bending stiffness, h p 、E p and p are thickness, Young's modulus and Poisson's ratio respectively; To solve the above differential equation, the displacement function of the annular plate is

[0063]

[0064]

[0065]

[0066] In the formula,

[0067]

[0068]

[0069] Ψ pw,n5 =J n (k pB r),Ψ pw,n6 =I n (k pB r),Ψ pw,n7 =Y n (k pB r),Ψ pw,n8 =K n (k pB r) (11)

[0070] Substituting the above displacement function into the internal force expression of the annular plate, the displacement and internal force on the boundary are expressed by matrix as follows:

[0071]

[0072] Furthermore, when analyzing the circular plate, the inner radius of the circular plate can be set to be small enough, generally R / 100, and the corresponding boundary condition can be set to a free boundary;

[0073] When an external force is applied to the center point of the circular plate, the vibration control equation of the circular plate under different excitations can be obtained by simply modifying the corresponding boundary conditions and combining them with the boundary conditions at the outer radius of the circular plate.

[0074] Another object of the present invention is to provide a simplified calculation system for low-frequency impedance of a pipeline structure in an underwater vehicle, comprising:

[0075] Model building module, used to establish simplified mathematical models for impedance calculation for different piping systems;

[0076] The solution module is used to establish the vibration equation of the mathematical model, solve its origin response, and then obtain the impedance solution;

[0077] The prediction module is used to generate programs to complete rapid impedance prediction.

[0078] Another object of the present invention is to provide a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for designing the low-frequency impedance of the pipeline structure in the underwater vehicle.

[0079] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the method for designing the low-frequency impedance of a pipeline structure in an underwater vehicle.

[0080] Another object of the present invention is to provide an information data processing terminal, which is used to implement a simplified calculation system for the low-frequency impedance of the pipeline structure in the underwater vehicle.

[0081] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0082] First, the low-frequency impedance design method of the pipeline structure in the underwater vehicle provided by the present invention includes the following steps: establishing a simplified mathematical model for impedance calculation for different pipeline systems; establishing a vibration equation for the mathematical model, solving its origin response, and then obtaining the impedance solution; generating a program to complete the rapid prediction of impedance. A method for rapid estimation of low-frequency impedance of typical pipeline structures in underwater vehicles, including sea pipelines, cabin pipelines, and supports and hangers. Based on the impedance method, the present invention establishes a mathematical model for impedance calculation of different pipeline and shell coupling structures, studies the effect of the pipeline structure on the underwater vehicle in the low-frequency band, simplifies the effect into a force or bending moment applied to the shell, and obtains its impedance theoretical solution by analyzing the vibration characteristics of the shell structure, thereby realizing rapid prediction of impedance.

[0083] Second, the pipeline needs to be designed during the ship design process. In order to ensure good vibration isolation of the pipeline, its cross-point impedance performance to the hull must be effectively estimated. At present, the estimation of pipeline impedance is mainly based on finite element calculation or experimental testing. When the ship structure is large, the finite element calculation takes a long time and has low calculation efficiency, and the arrangement of measurement points for experimental testing is more difficult. Therefore, the present invention obtains the impedance value of the hull pipeline structure through a rapid prediction method, which can provide a reference for the initial design stage of the hull structure. The calculation results are similar to the finite element calculation results, and the calculation process is faster.

[0084] Third, the technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0085] Mechanical impedance, as one of the important parameters of acoustic design, determines the proportion of vibration energy input into the hull through the structure. In order to reduce the input power and reduce the vibration and acoustic radiation of the hull structure, increasing the input mechanical impedance is a convenient and effective method. Through a large number of theoretical analyses, numerical experiments and actual ship tests, an effective impedance estimation method related to the base has been established, but the impedance analysis mechanism of the pipeline system has not yet been fully established. At present, it is an effective vibration control technical approach to control vibration transmission by utilizing the physical mechanism of impedance mismatch between components of the pipeline system. The present invention establishes a low-frequency impedance rapid estimation method for typical pipeline structures in underwater vehicles, including seagoing pipelines, cabin pipelines and supports and hangers, which can realize the estimation of pipeline impedance in the design stage, which is of great value for engineering applications.

[0086] Fourth, the present invention proposes an innovative low-frequency impedance design method for typical pipeline systems (sea pipelines, through-tank pipelines, and supports and hangers) in underwater vehicles. The core idea of ​​this method is to simplify the vibration characteristics of these pipeline systems into simple system models under concentrated forces by comprehensively analyzing them. This simplification enables us to understand the dynamic response characteristics of the system more intuitively, laying the foundation for subsequent impedance calculations.

[0087] In the specific implementation, the present invention first establishes simplified mathematical models for impedance calculation for different pipeline systems. These models accurately reflect the deformation and vibration behavior of the pipeline system under stress. Then, by establishing and solving the vibration equation for the mathematical model, we obtain the origin response of the system and then calculate the impedance solution. This step not only demonstrates the technical depth of the present invention, but also reflects its accuracy and reliability in solving practical problems.

[0088] In order to achieve impedance prediction more efficiently, the present invention has also developed a set of programs that can automatically generate the data and parameters required for impedance calculation and quickly complete impedance prediction. This innovation not only improves work efficiency, but also makes impedance prediction more convenient and accurate. Through this method, we can more accurately predict the impedance characteristics of underwater vehicles in the low-frequency band, providing an important reference for the design and optimization of vehicles.

[0089] In general, the present invention successfully solves the problem of low-frequency impedance design of pipeline structures in underwater vehicles by simplifying mathematical models, establishing vibration equations, and developing rapid prediction programs. Compared with the prior art, the present invention not only improves the accuracy and reliability of the design, but also greatly improves the work efficiency. This significant technological advancement is of great significance to the design and optimization of underwater vehicles and is expected to be widely used and promoted in the future.

[0090] Fifth, the present invention aims to solve the technical problems existing in the industrial application of the prior art, as well as the significant technological progress achieved in industrial applications. First, the traditional underwater vehicle pipeline structure design lacks systematicity and efficiency, and often faces the problems of low impedance prediction accuracy and long design cycle. In response to this problem, the present invention proposes a low-frequency impedance design method for pipeline structures based on comprehensive analysis and mathematical modeling. By simplifying the mathematical model and finite element simulation comparison, the accurate prediction of impedance is achieved, which greatly shortens the design cycle.

[0091] Secondly, in the traditional pipeline structure design process, there is a lack of methods to fully consider the vibration characteristics of the pipeline system, which often leads to a large deviation between the design results and the actual working environment. The present invention abstracts the pipeline system into a simple system, combines mechanical dynamics principles and finite element analysis technology, and fully considers the force characteristics and vibration characteristics of the pipeline system, achieving accurate prediction of low-frequency impedance and improving the accuracy and reliability of the design.

[0092] In addition, the traditional pipeline structure design method lacks effective use of experimental data, which often leads to large deviations between the design results and the actual situation. The present invention proposes a prediction system that integrates machine learning and experimental data, which automatically learns the experimental data features through machine learning algorithms, improves the accuracy and adaptability of pipeline structure impedance prediction, and provides a more reliable design reference for engineering practice.

[0093] Finally, the industrial application of the present invention has achieved significant technological progress and provided important support for the design, manufacture and operation of underwater vehicles. By improving the accuracy and efficiency of pipeline structure design, the present invention is expected to reduce the design cost of underwater vehicles, improve work efficiency, and thus promote the development and application of underwater vehicle technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 It is a flow chart of a method for designing low-frequency impedance of a pipeline structure in an underwater vehicle provided by an embodiment of the present invention.

[0095] Figure 2 It is a structural block diagram of a simplified calculation system for low-frequency impedance of a pipeline structure in an underwater vehicle provided by an embodiment of the present invention.

[0096] Figure 3 It is a pipeline impedance estimation flow chart provided by an embodiment of the present invention.

[0097] Figure 4 It is a schematic diagram of a sea-access pipeline provided by an embodiment of the present invention.

[0098] Figure 5 It is a simplified model diagram of a sea-access pipeline provided by an embodiment of the present invention.

[0099] Figure 6 It is a partial schematic diagram of the support and hanger provided in an embodiment of the present invention.

[0100] Figure 7 It is a simplified schematic diagram of the support and hanger provided in an embodiment of the present invention.

[0101] Figure 8 It is an equivalent mechanical circuit diagram provided by an embodiment of the present invention.

[0102] Fig. 9 It is a schematic diagram of the through-cabin pipeline provided by an embodiment of the present invention.

[0103] Fig.10 It is a simplified schematic diagram of the through-cabin pipeline provided in an embodiment of the present invention.

[0104] Fig.11 It is a simplified model diagram of the through-tank piping provided in an embodiment of the present invention.

[0105] Fig.12 It is a finite element comparison diagram of the sea-going pipeline provided by an embodiment of the present invention.

[0106] Fig.13 It is a comparison diagram of the impedance of the support bracket origin provided by an embodiment of the present invention.

[0107] Fig.14 It is a comparison diagram of the cross-point impedance of the support and hanger provided in an embodiment of the present invention.

[0108] Fig.15 1 is a comparison diagram of the vibration response of a circular plate provided by an embodiment of the present invention. (a) Normal impedance of the excitation point under the action of normal force; (b) Radial impedance of the excitation point under the action of radial force. DETAILED DESCRIPTION

[0109] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0110] The following are two specific embodiments of the present invention in industrial applications:

[0111] Embodiment 1: During the design phase of an underwater vehicle, engineers need to accurately predict the low-frequency impedance of the sea-going pipeline to ensure the stability and safety of the vehicle when operating underwater. Using the impedance design method of the present invention, engineers first established a simplified mathematical model for impedance calculation based on the actual structure and size of the sea-going pipeline. Then, they used the model to establish the vibration equation, and obtained the origin response and impedance solution by solving it. Finally, the impedance prediction data was automatically generated by the program. These data provide engineers with detailed information on the impedance characteristics of the sea-going pipeline in the low-frequency band, helping them optimize the design and layout of the vehicle, thereby improving the stability and performance of the vehicle.

[0112] Embodiment 2: In the field of marine engineering, through-cabin pipelines are important channels connecting subsea facilities with surface platforms. These pipelines are subjected to complex loads and vibrations during operation, so accurate impedance design is required. Using the impedance design method of the present invention, engineers first conducted a detailed force analysis of the through-cabin pipelines and established a simplified mathematical model for impedance calculation. Then, they established the vibration equation based on the model, and obtained the origin response and impedance solution by solving it. In order to verify the accuracy of the prediction results, the engineers also used finite element simulation software for comparative analysis. Finally, through the impedance data generated by the rapid prediction program, the engineers successfully carried out the impedance design of the through-cabin pipelines, ensuring the safe connection and stable operation between the subsea facilities and the surface platform.

[0113] like Figure 1 As shown, a method for designing low-frequency impedance of a pipeline structure in an underwater vehicle provided by an embodiment of the present invention comprises the following steps:

[0114] S101, establish a simplified mathematical model for impedance calculation for different pipeline systems;

[0115] S102, establishing a vibration equation for the mathematical model, solving its origin response, and then obtaining an impedance solution;

[0116] S103, generating a program to complete the impedance rapid prediction.

[0117] The present invention aims to provide a method for designing the low-frequency impedance of a pipeline structure in an underwater vehicle. The method comprehensively analyzes the vibration characteristics of a typical pipeline system and abstracts it into a simple system under the action of a concentrated force. The force analysis is performed based on the force characteristics, and the motion equations are listed. The origin impedance is then solved and the cross-point impedance is obtained by using an approximate or electroacoustic analogy method. Finally, the finite element simulation is used for comparison to realize the prediction of the low-frequency impedance of the underwater vehicle.

[0118] 1. Establish a simplified mathematical model for impedance calculation:

[0119] -For different piping systems, according to their structural characteristics and stress conditions, corresponding simplified mathematical models for impedance calculation are established. These models abstract the piping system into a simple system under the action of concentrated force, which is convenient for subsequent analysis and calculation.

[0120] 2. Establishment and solution of vibration equation:

[0121] -Establish vibration equations for mathematical models, and list corresponding motion equations based on the stress conditions and dynamic characteristics of the piping system. These equations describe the response behavior of the piping system when subjected to external excitation.

[0122] -Further solve these motion equations to obtain the origin response of the piping system, that is, the response when a unit force is applied at the origin.

[0123] 3. Impedance solution calculation:

[0124] -According to the origin response, the impedance solution of the piping system is calculated. The impedance solution reflects the impedance characteristics of the piping structure at different frequencies and is an important parameter for evaluating the vibration characteristics of the piping system.

[0125] 4. Rapid impedance prediction:

[0126] -Generate corresponding programs or algorithms for rapid prediction of impedance of pipeline structures. These programs can quickly calculate the corresponding impedance values ​​based on given pipeline system parameters and external excitation conditions, providing important reference for the design and optimization of underwater vehicles.

[0127] Through the above steps, the present invention realizes the design and prediction of the low-frequency impedance of the pipeline structure in the underwater vehicle, and provides important technical support for the structural design and performance optimization of the underwater vehicle.

[0128] The method for establishing a simplified mathematical model for impedance calculation provided by the embodiment of the present invention is as follows:

[0129] (1) Low-frequency impedance prediction of sea-going pipelines;

[0130] (2) Low-frequency impedance prediction of supports and hangers;

[0131] (3) Prediction of low-frequency impedance of pipelines through the cabin.

[0132] The low-frequency impedance prediction of the sea-going pipeline provided by the embodiment of the present invention:

[0133] The expression of compartment ring frequency is as follows:

[0134]

[0135] Where R is the cabin radius, C l is the longitudinal wave velocity of a plate with the same thickness as the cylindrical shell,

[0136] The differential equation of motion of a cylindrical shell can be expressed as:

[0137]

[0138] Where R, h, E and υ are the radius, thickness, Young's modulus and Poisson's ratio of the cylindrical shell respectively; [L ij ] is the shell differential operator, {U}={u,v,w} T represents the axial, circumferential and radial displacements of the shell, {F} is the excitation force acting on the shell, and {q} = {0,0,q r} is the sound pressure of the external fluid acting on the shell surface;

[0139] Assume that N acts on the shell F point excitation, where the kth excitation axial and circumferential excitation is (x k ,θ k ), then the excitation force vector {F} is:

[0140]

[0141] Among them, F kx 、F kθ 、F kr 、M kx 、M kθ and M kxθ To act on (x k ,θ k ) out of the axial force, circumferential force, radial force, axial moment, circumferential moment and radial moment; δ is the Dirac function;

[0142] When both ends of the cylindrical shell are simply supported boundaries, the displacement function can be expressed as:

[0143]

[0144]

[0145]

[0146] In the formula, k m =mπ / L, α=1 (or 0) represents the symmetric mode (antisymmetric mode), m and n represent the axial half-wave number and the circumferential wave number respectively;

[0147] The radiated sound pressure of a finite length cylindrical shell simply supported at both ends on a rigid cylindrical baffle can be expressed as:

[0148]

[0149] In the formula,

[0150]

[0151] Where k0 = ω / c0, Therefore, the sound pressure {q} of the fluid acting on the single-layer cylindrical shell is ir for:

[0152] q r =p(R,θ,x) (7)

[0153] Substituting equations (3)-(7) into equation (2) and applying the orthogonality of trigonometric functions, both the symmetric mode and the antisymmetric mode can obtain a system of m×n×3 independent equations. Solving this system of equations can obtain all the displacement terms {U αmn ,V αmn ,W αmn} T ;

[0154] After obtaining the displacement response, the origin impedance of the cylindrical shell can be obtained by solving the following equation:

[0155]

[0156] The low-frequency impedance prediction of the support and hanger provided by the embodiment of the present invention:

[0157] The impedance at the mass point is: Z1 = jωm, and the impedance at the spring is: Z3 is the origin impedance of the support and hanger rooting position;

[0158] The origin impedance of the support bracket is

[0159]

[0160] The span impedance at the support bracket position is

[0161]

[0162] The low-frequency impedance prediction of the through-tank pipeline provided by the embodiment of the present invention is as follows:

[0163] The differential equation of motion of the circular plate / annular plate is

[0164]

[0165]

[0166]

[0167] In the formula, is the plate bending stiffness, h p 、E p and p are thickness, Young's modulus and Poisson's ratio respectively; To solve the above differential equation, the displacement function of the annular plate is

[0168]

[0169]

[0170]

[0171] In the formula,

[0172]

[0173]

[0174] Ψ pw,n5 =J n (k pB r),Ψ pw,n6 =I n (k pB r),Ψ pw,n7 =Y n (k pB r),Ψ pw,n8 =K n (k pB r) (11)

[0175] Substituting the above displacement function into the internal force expression of the annular plate, the displacement and internal force on the boundary are expressed by matrix as follows:

[0176]

[0177] When analyzing the circular plate provided in the embodiment of the present invention, the inner radius of the circular plate can be set to be small enough, generally R / 100, and the corresponding boundary condition is set to be a free boundary;

[0178] When an external force is applied to the center point of the circular plate, the vibration control equation of the circular plate under different excitations can be obtained by simply modifying the corresponding boundary conditions and combining them with the boundary conditions at the outer radius of the circular plate.

[0179] like Figure 2As shown, a simplified calculation system for low-frequency impedance of a pipeline structure in an underwater vehicle provided by an embodiment of the present invention includes:

[0180] Model building module, used to establish simplified mathematical models for impedance calculation for different piping systems;

[0181] The solution module is used to establish the vibration equation of the mathematical model, solve its origin response, and then obtain the impedance solution;

[0182] The prediction module is used to generate programs to complete rapid impedance prediction.

[0183] A computer device is provided in an embodiment of the present invention, the computer device comprising a memory and a processor, the memory storing a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for designing low-frequency impedance of a pipeline structure in an underwater vehicle.

[0184] A computer-readable storage medium provided by an embodiment of the present invention stores a computer program. When the computer program is executed by a processor, the processor executes the steps of the method for designing low-frequency impedance of a pipeline structure in an underwater vehicle.

[0185] An embodiment of the present invention provides an information data processing terminal, which is used to implement a simplified calculation system for low-frequency impedance of a pipeline structure in the underwater vehicle.

[0186] The present invention is specifically implemented:

[0187] Figure 3 Pipeline impedance estimation flow chart

[0188] Theory of low-frequency impedance prediction for sea-going pipelines

[0189] The schematic diagram of a typical sea pipeline is as follows: Figure 4 As shown in the figure, the excitation generated by the sea-going pipeline directly acts on the shell. Due to the existence of the flexible pipe at the end, the force form of the sea-going port is complex and can be decomposed into forces and moments in the radial, axial and circumferential directions along the shell surface. When the analysis frequency is above the cylindrical shell ring frequency, the input mechanical impedance is irrelevant to the boundary conditions because the bending wave wavelength is too small and can be regarded as an infinite plate. Therefore, only the low frequency band below the ring frequency is considered.

[0190] The expression of compartment ring frequency is as follows:

[0191]

[0192] In the formula, C l is the longitudinal wave velocity of a plate with the same thickness as the cylindrical shell,

[0193] The simplified mathematical model of the low-frequency band of the sea-going pipeline can be established as the origin impedance of the cylindrical shell under six excitations. When conducting vibration analysis of the sea-going pipeline, the excitation force of the sea-going port is solved according to the above form. The simplified mathematical model is as follows Figure 5 shown.

[0194] For the impedance calculation of the simplified model above, firstly, the vibration control equation of the cylindrical shell under multiple excitations is established. Based on the Flügge thin shell theory, the differential equation of motion of the cylindrical shell can be expressed as:

[0195]

[0196] Where R, h, E and υ are the radius, thickness, Young's modulus and Poisson's ratio of the cylindrical shell respectively; [L ij ] is the shell differential operator, {U}={u,v,w} T represents the axial, circumferential and radial displacements of the shell, {F} is the excitation force acting on the shell, and {q} = {0,0,q r} is the sound pressure of the external fluid acting on the shell surface.

[0197] Assume that N acts on the shell F point excitation, where the kth excitation axial and circumferential excitation is (x k ,θ k ), then the excitation force vector {F} is:

[0198]

[0199] Among them, F kx 、F kθ 、F kr 、M kx 、M kθ and M kxθ To act on (x k ,θ k ) are the axial force, circumferential force, radial force, axial moment, circumferential moment and radial moment; δ is the Dirac function.

[0200] When both ends of the cylindrical shell are simply supported boundaries, the displacement function can be expressed as:

[0201]

[0202]

[0203]

[0204] In the formula, k m =mπ / L, α=1 (or 0) represents the symmetric mode (antisymmetric mode), m and n are the axial half-wave number and the circumferential wave number, respectively.

[0205] The radiated sound pressure of a finite length cylindrical shell simply supported at both ends on a rigid cylindrical baffle can be expressed as:

[0206]

[0207] In the formula,

[0208]

[0209] Where k0 = ω / c0, Therefore, the sound pressure {q} of the fluid acting on the single-layer cylindrical shell is ir for:

[0210] q r =p(R,θ,x) (7)

[0211] Substituting equations (3)-(7) into equation (2) and applying the orthogonality of trigonometric functions, both the symmetric mode and the antisymmetric mode can obtain a system of m×n×3 independent equations. Solving this system of equations can obtain all the displacement terms {U αmn ,V αmn ,W αmn} T .

[0212] After obtaining the displacement response, the origin impedance of the cylindrical shell can be obtained by solving the following equation:

[0213]

[0214] Theory of low frequency impedance prediction of supports and hangers

[0215] The schematic diagram of a typical support and hanger is as follows: Figure 6 As shown, in actual situations, the same pipeline often has many supports and hangers to control its vibration. The supports and hangers are connected in parallel, and the total impedance of the supports and hangers is the sum of the number of all supports and hangers. The supports and hangers are connected in series with the hull, and the gravity of the pipeline is evenly distributed on each support and hanger.

[0216] Because the support bracket is directly connected to the shell, its simplified schematic diagram is as follows Figure 7 shown.

[0217] The support bracket is in the form of elastic support, and its stiffness is K. The support bracket is connected to the shell, the upper end is connected to the cylindrical shell, and the lower end is connected to the mass point. It is converted into an equivalent mechanical circuit diagram through electroacoustic analogy, as follows Figure 8 shown.

[0218] Among them, the impedance at the mass point is: Z1 = jωm, and the impedance at the spring is: Z3 is the origin impedance of the support and hanger rooting position (shell), which can be calculated using the impedance of the cylindrical shell under radial force derived from the sea pipeline section.

[0219] Therefore, the origin impedance of the support bracket is

[0220]

[0221] The span impedance at the support bracket position is

[0222]

[0223] Theory of low frequency impedance prediction for pipelines through cabins

[0224] The schematic diagram of the through-tank pipeline is as follows Fig. 9 The excitation generated by the through-cabin pipeline directly acts on the bulkhead structure, and the bulkhead structure then transmits the excitation to the shell.

[0225] The impedance of the shell under the excitation of the through-tank pipeline can be simplified to the impedance of a cylindrical shell with the bulkhead subjected to axial force and radial force, where the axial force can be converted into a radial bending moment acting on the shell, and the radial force acts directly on the shell along the bulkhead. The simplified model diagram is shown in the figure below: Fig.10 shown.

[0226] The calculation of cylindrical shell impedance has been derived in detail in the section on sea-going pipelines. In order to obtain the excitation of the pipeline on the bulkhead, it is necessary to estimate the impedance of the origin of the through-cabin pipeline.

[0227] Since the stiffness of the bulkhead and the shell is similar, the impedance of the through-cabin pipeline can be simplified to the impedance of a four-sided simply supported circular plate under the action of radial force and axial force. The mathematical model is as follows: Fig.11 shown.

[0228] Based on the thin plate theory, the differential equation of motion of the circular plate / annular plate is

[0229]

[0230]

[0231]

[0232] In the formula, is the plate bending stiffness, h p 、E p and p are thickness, Young's modulus and Poisson's ratio respectively. To solve the above differential equation, the displacement function of the annular plate is

[0233]

[0234]

[0235]

[0236] In the formula,

[0237]

[0238]

[0239] Ψ pw,n5 =J n (k pB r),Ψ pw,n6 =I n (k pB r),Ψ pw,n7 =Y n (k pB r),Ψ pw,n8 =K n (k pB r) (11)

[0240] Substituting the above displacement function into the internal force expression of the annular plate, the displacement and internal force on the boundary are expressed by matrix as follows:

[0241]

[0242] When analyzing a circular plate, the inner radius of the circular plate can be set small enough, generally R / 100, and the corresponding boundary condition can be set as a free boundary. When an external force is applied to the center of the circular plate, the vibration control equation of the circular plate under different excitations can be obtained by simply modifying the corresponding boundary conditions and combining them with the boundary conditions at the outer radius of the circular plate.

[0243] After obtaining the displacement response under forced vibration, the impedance expression of the circular plate is as follows:

[0244]

[0245] Impedance prediction results

[0246] A cylindrical shell model with two ends simply supported was established for the Tonghai Pipeline to estimate and compare the above predictions. The cylindrical shell length L = 10m, radius R = 3.5m, shell thickness H = 0.028m, material is steel, density 7850kg / m 3 , Young's modulus is 210GPa, Poisson's ratio is 0.3, and loss factor is 0.01. The comparison between the finite element results and the theoretical results is as follows:

[0247] Depend on Fig.12It can be seen that the low-frequency theoretical calculation results of the sea-going pipeline are well compared with the finite element simulation results. The best correspondence is between the theoretical solution under radial force and the impedance finite element calculation results. Under the action of axial and tangential bending moments, there is a certain peak offset between the impedance theoretical solution and the finite element solution, but they are in the same order of magnitude and have the same trend. The finite element calculation results fluctuate around the theoretical solution. Under radial force, there is a large resonance peak due to the presence of the end plate during finite element modeling, but the impedance calculation results are generally accurate.

[0248] The support and hanger establishes a cylindrical shell model with two ends simply supported to estimate and compare the above predictions. The material parameters of the cylindrical shell are the same as those of the sea-going pipeline. The difference is that there is a spring with a stiffness of 107N / m in the middle of the cylindrical shell, and there is a mass point with a mass of 1000kg above the spring. A radial force is applied at the mass point. The comparison between the finite element results and the theoretical results is as follows:

[0249] Depend on Fig.13 , 14 It can be seen that the low-frequency theoretical calculation results of the support and hanger are in good comparison with the finite element simulation results, with similar magnitudes, but different peak and valley positions. The finite element calculation results fluctuate above and below the theoretical solution, which can meet the needs of engineering estimation.

[0250] The through-tank pipeline is built with simply supported steel circular plates on all sides, with radius and thickness set to 3.5m and 0.03m respectively; normal force and radial force are applied to the center of the plate respectively, and the calculation frequency is 1-200Hz. The comparison between the finite element results and the theoretical results is as follows Fig.15 :

[0251] When the normal excitation is applied, only the axisymmetric mode of the circular plate, i.e., the n=0 mode, can be excited. The two modes are well matched at low frequencies, but peak shift occurs when the frequency increases. When the radial excitation is applied, since the in-plane stiffness of the circular plate is significantly higher than the out-of-plane bending stiffness, only one resonance peak appears in the range of 1-200Hz, and the resonance peak frequencies and amplitudes obtained by the two methods are consistent. Overall, the theoretical model is well matched with the FEM results, which verifies the correctness of the solution of the circular plate's origin impedance.

[0252] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0253] The present invention respectively establishes a cylindrical shell model with two ends simply supported, a steel annular plate with four sides simply supported, and a cylindrical shell model with two ends simply supported with springs to simulate the effects of seagoing pipelines, through-cabin pipelines, and supports and hangers on the hull, which can realize the rapid prediction of impedance, and the impedance results obtained are similar to the simulation. Through the obtained impedance results, the vibration characteristics of the hull containing the pipeline structure can be analyzed, and the vibration isolation performance of the pipeline and hull structure can be evaluated through the impedance characteristics. The through-cabin pipeline section can be used to study the effect of the bulkhead on the vibration of the hull, and the impedance results can be used as an effective evaluation parameter for the vibration isolation design of the equipment.

[0254] The present invention compares the theoretical results through simulation experiments, and respectively establishes a cylindrical shell model with two ends simply supported, a steel annular plate with four sides simply supported, and a cylindrical shell model with two ends simply supported with springs to simulate the sea pipeline, the cabin pipeline and the support bracket and perform finite element simulation. The simulation results are as follows Figure 12-15 As shown, the theoretical calculation results are well compared with the finite element simulation results, and the magnitude is comparable. The finite element calculation results fluctuate around the theoretical solution. This can meet the needs of impedance engineering estimation. After obtaining the impedance results, vibration and acoustic performance analysis based on impedance can be performed.

[0255] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for designing low-frequency impedance of a pipeline structure in an underwater vehicle, characterized in that: The following steps are involved: Step 1: Establish a simplified mathematical model for impedance calculation for different pipeline systems; Step 2: Establish the vibration equation of the mathematical model, solve its origin response, and then obtain the impedance solution; Step 3: Generate a program to complete the impedance rapid prediction; The method for establishing a simplified mathematical model for impedance calculation is as follows: (1) Low-frequency impedance prediction of sea-going pipelines; (2) Low-frequency impedance prediction of supports and hangers; (3) Low-frequency impedance prediction of pipelines through the cabin; The low-frequency impedance prediction of the sea-going pipeline: The expression of compartment ring frequency is as follows: In the formula, C l is the longitudinal wave velocity of a plate with the same thickness as the cylindrical shell, The differential equation of motion of a cylindrical shell is expressed as: Where R, h, E and υ are the radius, thickness, Young's modulus and Poisson's ratio of the cylindrical shell respectively; [L ij ] is the shell differential operator, {U}={u,v,w} T represents the axial, circumferential and radial displacements of the shell, {F} is the excitation force acting on the shell, and {q} = {0,0,q r } is the sound pressure of the external fluid acting on the shell surface; Assume that N acts on the shell F point excitation, where the kth excitation axial and circumferential excitation is (x k ,θ k ), then {F} is: Among them, F kx 、F kθ 、F kr 、M kx 、M kθ and M kxθ They act on (x k ,θ k ) at the axial force, circumferential force, radial force, axial moment, circumferential moment and radial moment; δ is the Dirac function; When both ends of the cylindrical shell are simply supported boundaries, the displacement function is expressed as: In the formula, k m =mπ / L, α=1 represents a symmetric mode, α=0 represents an antisymmetric mode, m and n are the axial half-wave number and the circumferential wave number respectively; the radiated sound pressure of a finite-length cylindrical shell simply supported at both ends on a rigid cylindrical baffle is expressed as: In the formula, Where k0 = ω / c0, Therefore, q in {q} r for: q r =p(R,θ,x)(7) Substituting equations (3)-(7) into equation (2) and applying the orthogonality of trigonometric functions, both the symmetric mode and the antisymmetric mode can obtain a system of m×n×3 independent equations. Solving the system of equations yields all the displacement terms {Uα mn ,Vα mn ,Wα mn } T ; After obtaining the displacement response, the origin impedance of the cylindrical shell can be obtained by solving the following equation:

2. The method for designing low-frequency impedance of a pipeline structure in an underwater vehicle as claimed in claim 1, characterized in that: The low frequency impedance prediction of the support and hanger: The impedance at the mass point is: Z1 = jωm1, and the impedance at the spring is: Z3 is the origin impedance of the support and hanger rooting position; The origin impedance of the support bracket is The span impedance at the support bracket position is 3. The method for designing low-frequency impedance of a pipeline structure in an underwater vehicle as claimed in claim 1, characterized in that: Set the inner radius of the annular plate to R / 100, and set the corresponding boundary condition to free boundary; When an external force is applied to the center point of the circular plate, the vibration control equation of the circular plate under different excitations can be obtained by simply modifying the corresponding boundary conditions and combining them with the boundary conditions at the outer radius of the circular plate.

4. A simplified calculation system for low-frequency impedance of a pipeline structure in an underwater vehicle implementing the method for designing low-frequency impedance of a pipeline structure in an underwater vehicle as claimed in any one of claims 1 to 3, characterized in that: The simplified calculation system for low-frequency impedance of a pipeline structure in an underwater vehicle comprises: Model building module, used to establish simplified mathematical models for impedance calculation for different piping systems; The solution module is used to establish the vibration equation of the mathematical model, solve its origin response, and then obtain the impedance solution; The prediction module is used to generate programs to complete rapid impedance prediction.

5. A low-frequency impedance design method for a pipeline structure in an underwater vehicle based on the design method of claim 1, characterized in that: The method comprises the following steps: According to the actual structure and size of the pipeline system in the underwater vehicle, a simplified mathematical model for impedance calculation is established, which can reflect the vibration characteristics of the pipeline system under stress. On the basis of simplified mathematical model, the vibration equation is established, and the origin response of the piping system is obtained by solving the equation. Based on the origin response, the impedance solution of the pipeline system is calculated, and the cross-point impedance is obtained using approximate or electroacoustic analogy methods; Write a program that can automatically generate the data and parameters required for impedance calculation and quickly complete impedance prediction, providing data support for the design and optimization of underwater vehicles.

6. A low-frequency impedance design system for underwater vehicles and pipeline structures in marine engineering based on the design method of claim 1, characterized in that: The system includes: A data input module, for receiving actual structure and size data about the piping system; The model building module automatically builds a simplified mathematical model for impedance calculation based on the received data; The vibration analysis module performs vibration analysis on the established mathematical model, establishes and solves the vibration equation, and obtains the origin response of the piping system; The impedance calculation module calculates the impedance solution of the pipeline system based on the origin response and obtains the cross-point impedance using the electroacoustic analogy method; The prediction output module automatically generates impedance prediction data through the program and outputs it in the form of visualization or data report to provide decision support for the design and optimization of pipeline structure.

7. An information data processing terminal, characterized in that: The information data processing terminal is used to implement the simplified calculation system for the low-frequency impedance of the pipeline structure in the underwater vehicle as described in claim 4.

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