A local oscillator optimization design method for cylindrical shell vibration reduction

Abstract

The invention relates to a local oscillator optimization design method for cylindrical shell vibration reduction, comprising: constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, and obtaining the dynamic equation of the cylindrical shell physical model to determine the resonance frequency band of the cylindrical shell including the superstructure unit; dividing a plurality of superstructure unit groups; determining structural parameters for influencing the resonance frequency of the superstructure unit, and constructing an optimization parameter group for all superstructure unit groups; determining the resonance frequency of a superstructure unit group, and constructing the distribution law of the resonance frequencies between the plurality of superstructure unit groups; adding material parameters to the cylindrical shell physical model and exciting it, and picking up the frequency response of the outer surface of the cylindrical shell physical model; constructing an optimization model based on the optimization parameter group, the distribution law and the frequency response, and determining the optimal solution of the structural parameters in the optimization parameter group based on the optimization model and with the minimum vibration amplitude as the goal, so as to realize the optimization of the local oscillator for cylindrical shell vibration reduction.

Description

Technical Field

[0001] The invention relates to the field of vibration control, and in particular to a local vibrator optimization design method for cylindrical shell vibration reduction. Background Art

[0002] Cylindrical shell structures are widely used in aviation, aerospace and navigation due to their excellent mechanical properties and light weight. Specific application equipment includes rockets, aircraft, etc. However, when various equipment, components and pipelines installed inside are working, the vibration of the cylindrical shell is aggravated, which seriously disrupts the stable working environment of its internal components, affects the physical and mental health of drivers and passengers, reduces the overall acoustic stealth characteristics of the structure, and even causes structural failure. Traditional vibration reduction measures, such as additional damping and structural modification, increase the mass and complexity of the system. Therefore, it is of great significance to propose lightweight and efficient vibration suppression methods to improve the acoustic stealth performance of cylindrical shell structures, extend the service life of the structure, and ensure the physical and mental health of combatants.

[0003] The introduction of acoustic superstructures provides a new idea for solving the above problems. Acoustic superstructures are a type of composite structure or composite material constructed by artificial microstructure units, which have properties that natural materials do not have, such as negative elastic modulus, negative mass density and negative refractive index. Since these extraordinary properties usually depend on microstructure units rather than material components, they provide new ideas and more possibilities for elastic wave regulation and structural functional material design. Acoustic superstructures can accurately regulate elastic waves through band gaps, but they have the disadvantage of narrow frequency bands and great limitations in broadband design. A multi-resonance idea has greatly expanded the broadband performance, but this requires precise control of the coupling effect between band gaps, which adds a lot of difficulty to the design. Summary of the invention

[0004] The object of the present invention is to provide a local vibrator optimization design method for cylindrical shell vibration reduction.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a local vibrator optimization design method for cylindrical shell vibration reduction, comprising the following steps:

[0006] S1. constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, and obtaining a dynamic equation of the cylindrical shell physical model to determine a resonant frequency band of the cylindrical shell including the superstructure unit; wherein the cylindrical shell is provided with reinforcing ribs, and the superstructure unit is periodically arranged on the inner side of the cylindrical shell;

[0007] S2. Divide the super structure unit into multiple super structure unit groups according to preset rules;

[0008] S3. Determine the structural parameters for influencing the resonance frequency of the superstructure unit, and construct an optimization parameter group for all the superstructure unit groups based on the structural parameters;

[0009] S4. Based on the structural parameters, determining the resonance frequency of one of the superstructure unit groups, wherein the determined resonance frequency of the superstructure unit group is the first resonance frequency when the cylindrical shell is in a bare shell state;

[0010] S5. constructing a distribution law of resonance frequencies between the plurality of superstructure unit groups;

[0011] S6. Adding material parameters to the cylindrical shell physical model and exciting a preset position of the cylindrical shell physical model to pick up a frequency response of the outer surface of the cylindrical shell physical model;

[0012] S7. Construct an optimization model for the cylindrical shell physical model based on the optimization parameter group, the distribution law and the frequency response, and determine the optimal solution of the structural parameters in the optimization parameter group based on the optimization model and with the minimum vibration amplitude as the goal, so as to achieve local oscillator optimization for cylindrical shell vibration reduction.

[0013] According to one aspect of the present invention, in step S1, in the step of obtaining the dynamic equation of the cylindrical shell physical model, the dynamic equation is expressed as:

[0014] ;

[0015] ;

[0016] ;

[0017] ;

[0018] ;

[0019] in, represents the mass matrix, , and denote the acceleration, velocity and displacement vector of the cylindrical shell, respectively. represents the damping matrix, represents the stiffness matrix, represents the mechanical load vector acting on the superstructure element, , , …, denote the mass of the superstructure unit, , , …, are the damping factors of the superstructure unit, , , …, They represent the stiffness of the superstructure unit, , , …, denote the load excitation acting on the superstructure unit, Represents the number of superstructure units.

[0020] According to one aspect of the present invention, in step S1, in the step of constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, the superstructure unit includes: a rubber part and a mass part;

[0021] The rubber part and the mass part are fixedly connected to each other;

[0022] The surface of the rubber part away from the mass part is arranged to match the inner side surface of the cylindrical shell;

[0023] The rubber part and the mass part have the same width and curvature.

[0024] According to one aspect of the present invention, the natural frequency of the superstructure unit is expressed as:

[0025] ;

[0026] in, is the natural frequency of the superstructure unit, is the equivalent mass of the superstructure unit, is the equivalent stiffness of the superstructure unit, subscript is the serial number of the superstructure unit.

[0027] According to one aspect of the present invention, in step S2, in the step of dividing the super-structure unit into a plurality of super-structure unit groups according to a preset rule, each of the super-structure unit groups contains a plurality of the super-structure units, and the structural parameters of the plurality of super-structure units in the same super-structure unit group are consistent;

[0028] The preset rule is: along the axial direction of the cylindrical shell physical model, multiple superstructure units in the same annular area are divided into a group; or along the circumferential direction of the cylindrical shell physical model, multiple superstructure units in the same arc area are divided into a group.

[0029] According to one aspect of the present invention, in step S3, in the step of determining the structural parameters for influencing the resonance frequency of the superstructure unit, and constructing the optimization parameter group of all the superstructure unit groups based on the structural parameters, the structural parameters include: the thickness of the rubber part of the rubber part , the mass portion thickness of the mass portion , the unit arc length of the superstructure unit ;

[0030] The optimization parameter group of the super structure unit group is expressed as:

[0031] ;

[0032] in, , , represents the structural parameters of the superstructure unit in the first group of superstructure units, , , represents the structural parameters of the superstructure unit in the second group of superstructure units, , , Indicates Group superstructure unit Structural parameters of the superstructure units in the group.

[0033] According to one aspect of the present invention, in step S5, in the step of constructing a distribution law of the resonance frequencies between the plurality of superstructure unit groups, the distribution law is that the resonance frequencies of the plurality of superstructure unit groups obey a geometric distribution and are expressed as:

[0034] ;

[0035] in, represents the resonant frequency of the first superstructure unit group, represents the resonant frequency of the second superstructure unit group, represents the resonant frequency of the third superstructure unit group, Indicates The resonant frequency of the superstructure unit group, Indicates The resonant frequency of the superstructure unit group, It represents the common ratio of the geometric progression distribution of the resonance frequencies of two adjacent groups of superstructure units, and it is a constant.

[0036] According to one aspect of the present invention, in step S6, in the step of exciting a preset position of the cylindrical shell physical model to pick up the frequency response of the outer surface of the cylindrical shell physical model, the middle and both ends of the cylindrical shell physical model are excited;

[0037] The frequency response is expressed as:

[0038] ;

[0039] in, , , Respectively indicate along , , The magnitude of the acceleration of the axis, represents the reference acceleration value, and .

[0040] According to one aspect of the present invention, in step S7, in the step of constructing an optimization model for the cylindrical shell physical model based on the optimization parameter group, the distribution law and the frequency response, the optimization model is expressed as:

[0041] ;

[0042] ;

[0043] ;

[0044] in, Indicates the initial parameters preset by the optimization parameter group. is the matrix used to represent the linear inequality constraints, is the matrix used to represent the linear inequality constraints, is the matrix used to represent the equality constraints, is the matrix used to represent the equality constraints, is the lower limit constraint of the structural parameters of the superstructure unit, is the upper limit constraint of the structural parameters of the superstructure unit, , , is the lower limit of the structural parameter of the superstructure unit, , , is the upper limit of the structural parameter of the superstructure unit, represents the fitness function value, f represents the optimized frequency range, i.e., the resonant frequency band of the cylindrical shell containing the superstructure unit.

[0045] According to one aspect of the present invention, the superstructure unit is a cubic arc structure;

[0046] In the superstructure unit, the rubber portion and the mass portion are connected by vulcanization.

[0047] According to one scheme of the present invention, the local oscillator optimization design method of the present invention is simple and efficient. Based on the excellent characteristics of acoustic superstructure wave regulation, the structural parameters of the superstructure unit are optimized to achieve broadband vibration suppression of the cylindrical shell, which has good engineering application value.

[0048] According to a solution of the present invention, compared with traditional vibration reduction solutions, the vibration reduction solution combined with the acoustic superstructure of the present invention is lighter and more effective, has a simpler design space, and realizes the flexible adjustability of the band gap, thereby better localizing the elastic waves and limiting their propagation.

[0049] According to a solution of the present invention, the present invention expansively couples the superstructure unit and the cylindrical shell for modeling, which greatly reduces the model calculation time, thereby realizing iterative optimization of structural parameters and completing a better vibration reduction design solution for the cylindrical shell.

[0050] According to one solution of the present invention, the present invention designs the resonance frequencies of multiple superstructure unit groups according to a geometric progression arrangement, which greatly broadens the broadband vibration suppression capability of the superstructure shell and realizes an efficient vibration reduction design.

[0051] According to one solution of the present invention, superstructure units are periodically added inside a cylindrical shell, and the superstructure units are grouped, and structural parameters of each group of units are optimized to achieve a broadband vibration reduction effect of the cylindrical shell; wherein the superstructure unit is a quasi-elastic-mass system composed of rubber mass blocks, and when the vibration frequency of the shell approaches the resonant frequency of the superstructure unit, the superstructure unit localizes the elastic wave, thereby quickly dissipating the vibration energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a block diagram schematically showing the steps of a local oscillator optimization design method according to an embodiment of the present invention;

[0053] Figure 2 is a diagram schematically showing a three-dimensional model of a cylindrical shell according to an embodiment of the present invention;

[0054] Figure 3 is a diagram schematically showing a physical model of a cylindrical shell according to an embodiment of the present invention;

[0055] Figure 4 is a diagram schematically showing a periodic arrangement of a three-dimensional model of a superstructure unit on the inner side of a three-dimensional model of a cylindrical shell according to an embodiment of the present invention;

[0056] Figure 5 Schematically showing a model diagram of a super-structure unit according to an embodiment of the present invention, wherein (a) shows a three-dimensional model diagram of the super-structure unit, and (b) shows a physical model diagram of the super-structure unit;

[0057] Figure 6 is a diagram schematically showing a grouping of superstructure units according to an embodiment of the present invention;

[0058] Figure 7is a diagram schematically showing an optimized structure of a superstructure unit according to an embodiment of the present invention;

[0059] Figure 8 It is a diagram schematically showing a comparison between the vibration reduction optimization results of the superstructure unit on the cylindrical shell according to an embodiment of the present invention and the control group. DETAILED DESCRIPTION

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0061] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0062] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0063] like Figure 1 As shown, according to one embodiment of the present invention, a local vibrator optimization design method for cylindrical shell vibration reduction of the present invention comprises the following steps:

[0064] S1. constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, and obtaining a dynamic equation of the cylindrical shell physical model to determine a resonant frequency band of the cylindrical shell including the superstructure unit; wherein a reinforcing rib is provided in the cylindrical shell, and the superstructure unit is periodically arranged on the inner side of the cylindrical shell;

[0065] S2. Divide the super-structure unit into multiple super-structure unit groups according to preset rules;

[0066] S3. Determine the structural parameters for influencing the resonance frequency of the superstructure unit, and construct an optimization parameter group for all superstructure unit groups based on the structural parameters;

[0067] S4. Based on the structural parameters, determining the resonance frequency of one of the superstructure unit groups, wherein the determined resonance frequency of the superstructure unit group is the first resonance frequency when the cylindrical shell is in a bare shell state;

[0068] S5. Construct the distribution law of resonance frequencies between multiple superstructure unit groups;

[0069] S6. Adding material parameters to the cylindrical shell physical model, and exciting a preset position of the cylindrical shell physical model to pick up a frequency response of the outer surface of the cylindrical shell physical model;

[0070] S7. Based on the optimization parameter group, distribution law and frequency response, an optimization model for the cylindrical shell physical model is constructed, and based on the optimization model and with the minimum vibration amplitude as the goal, the optimal solution of the structural parameters in each optimization parameter group is determined to achieve local oscillator optimization for cylindrical shell vibration reduction.

[0071] Combination Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, according to an embodiment of the present invention, in step S1, in the step of constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, a cylindrical shell three-dimensional model is constructed based on three-dimensional software, and further, based on the shell physics module in the finite element software, the cylindrical shell three-dimensional model is converted into a cylindrical shell physical model. In this embodiment, a reinforcing rib is arranged on the inner side of the cylindrical shell, wherein a plurality of reinforcing ribs are arranged at equal intervals along the axial direction of the cylindrical shell, and accordingly, the reinforcing rib is also retained in the constructed cylindrical shell physical model; in addition, the constructed cylindrical shell physical model also needs to retain the boundary conditions corresponding to the cylindrical shell (such as simply supported, fixedly supported, free, etc.) and other features.

[0072] Furthermore, the superstructure unit is an acoustic superstructure unit, which is a quasi-elastic-mass system as a whole. Specifically, the superstructure unit includes: a rubber part and a mass part. In this embodiment, the rubber part and the mass part are fixedly connected to each other; specifically, the rubber part and the mass part are connected by vulcanization. Furthermore, the surface of the rubber part away from the mass part is matched with the inner side of the cylindrical shell, wherein the rubber part is connected to the inner side of the cylindrical shell by a fixed connection, for example, by a bonding or vulcanization process.

[0073] In this embodiment, the superstructure unit is a cubic arc-shaped structure; wherein the rubber part can be set as an arc-shaped plate layer, and the mass part can be set as an arc-shaped plate layer.

[0074] In this embodiment, when the superstructure units are periodically arranged on the inner side of the cylindrical shell physical model, the superstructure units are fixed to the inner side of the cylindrical shell by bonding, and the superstructure units are arranged accordingly in the cylindrical shell three-dimensional model, wherein multiple circles of superstructure units are evenly spaced along the axial direction of the cylindrical shell, and multiple superstructure units are evenly spaced in each circle of superstructure units along the circumferential direction of the cylindrical shell. In this embodiment, the superstructure units can also be constructed using three-dimensional software and arranged on the corresponding cylindrical shell three-dimensional model. Furthermore, based on the multi-layer shell physics module in the finite element software, the three-dimensional model of the superstructure unit is converted into a superstructure unit physical model to achieve coupling on the inner side of the cylindrical shell physical model, see Figure 6 .

[0075] According to an embodiment of the present invention, in step S1, in the step of obtaining the dynamic equation of the cylindrical shell physical model, the dynamic equation is expressed as:

[0076] ;

[0077] ;

[0078] ;

[0079] ;

[0080] ;

[0081] in, represents the mass matrix, , and denote the acceleration, velocity and displacement vector of the cylindrical shell, respectively. represents the damping matrix, represents the stiffness matrix, represents the mechanical load vector acting on the superstructure element, , , …, denote the mass of the superstructure unit, , , …, are the damping factors of the superstructure unit, , , …, They represent the stiffness of the superstructure unit, , , …, denote the load excitation acting on the superstructure unit, Represents the number of superstructure units.

[0082] In this implementation, by solving the dynamic equation of the physical model of the cylindrical shell, the vibration response curve of the cylindrical shell can be obtained, thereby determining the resonance frequency band of the cylindrical shell.

[0083] Furthermore, assuming an undamped single degree of freedom, the natural frequency of the superstructure element is expressed as:

[0084] ;

[0085] in, is the natural frequency of the superstructure unit, is the equivalent mass of the superstructure unit, is the equivalent stiffness of the superstructure element, subscript is the serial number of the superstructure unit.

[0086] Therefore, based on the determined resonance frequency band of the cylindrical shell and the natural frequency formula of the superstructure unit, the equivalent mass can be realized. and equivalent stiffness to determine the scope.

[0087] Combination Figure 4 and Figure 5 As shown, according to an embodiment of the present invention, in step S2, in the step of dividing the superstructure unit into multiple superstructure unit groups according to a preset rule, each superstructure unit group contains multiple superstructure units, and the structural parameters of the multiple superstructure units in the same superstructure unit group are consistent; wherein the preset rule is: along the axial direction of the cylindrical shell physical model, multiple superstructure units in the same annular area are divided into a group; or, along the circumferential direction of the cylindrical shell physical model, multiple superstructure units in the same arc area are divided into a group.

[0088] In this embodiment, multiple superstructure units in the same arc region are divided into one group along the circumference of the cylindrical shell physical model, that is, a row of multiple superstructure units aligned along the axial direction of the cylindrical shell physical model is one group.

[0089] like Figure 5 As shown, according to an embodiment of the present invention, in step S3, the structural parameters for influencing the resonance frequency of the superstructure unit are determined, and in the step of constructing the optimization parameter group of all superstructure unit groups based on the structural parameters, since the rubber part and the mass part in the superstructure unit have structural parameters such as thickness, width / length or radius, respectively, the structural parameters selected here include: the thickness of the rubber part of the rubber part , the mass part thickness of the mass part , the unit arc length of the superstructure unit By adjusting the three specific parameters in the structural parameters, different equivalent masses can be obtained. and equivalent stiffness , thereby determining different resonant frequencies.

[0090] Further, based on the determined structural parameters of the super-structure unit and the parameters in the corresponding super-structure unit group, that is, ( ), ),…,( ) to construct the corresponding optimization parameter group, thus, the optimization parameter group of the super structure unit group is expressed as:

[0091] ;

[0092] in, , , represents the structural parameters of the superstructure unit in the first group of superstructure units, , , represents the structural parameters of the superstructure unit in the second group of superstructure units, , , Indicates Group superstructure unit Structural parameters of the superstructure units in the group.

[0093] According to one embodiment of the present invention, in step S4, in the step of determining the resonant frequency of one of the superstructure unit groups based on the structural parameters, one of the superstructure unit groups is selected as the first superstructure unit group, and the resonant frequency thereof can be made consistent with the first resonant frequency of the cylindrical shell by adjusting the structural parameters of the superstructure unit, wherein the first resonant frequency is the first resonant frequency of the cylindrical shell when the cylindrical shell is only a bare shell.

[0094] According to an embodiment of the present invention, in step S5, in the step of constructing the distribution law of the resonance frequencies between multiple superstructure unit groups, the resonance frequencies of the remaining superstructure unit groups can be determined based on the determined first superstructure unit group and the distribution law of the resonance frequencies between the determined multiple superstructure unit groups, thereby optimizing the design of the structural parameters of the superstructure units in each superstructure unit group based on all the determined resonance frequencies. In this embodiment, the determined distribution law is that the resonance frequencies of the multiple superstructure unit groups obey geometric distribution, and is expressed as:

[0095] ;

[0096] in, represents the resonant frequency of the first superstructure unit group, represents the resonant frequency of the second superstructure unit group, represents the resonant frequency of the third superstructure unit group, Indicates The resonant frequency of the superstructure unit group, Indicates The resonant frequency of the superstructure unit group, represents the common ratio of the geometric progression distribution of the resonance frequencies of two adjacent superstructure unit groups, and is a constant. Specifically, The value directly affects the bandwidth and performance of vibration control. In short, The smaller the value, the narrower the bandwidth of vibration control, but the stronger the vibration attenuation within the bandwidth. Conversely, the wider the bandwidth, the weaker the attenuation.

[0097] In this embodiment, different geometric distributions are achieved in the process of optimizing the structural parameters of the superstructure unit through the set distribution rules, thereby achieving different vibration suppression effects.

[0098] According to an embodiment of the present invention, in step S6, in the step of adding material parameters to the cylindrical shell physical model, the material parameters are set based on the materials of the cylindrical shell and the superstructure unit, as shown in Table 1.

[0099] Table 1

[0100]

[0101] Further, in step S7, the preset position of the cylindrical shell physical model is excited to pick up the frequency response of the outer surface of the cylindrical shell physical model, and the middle and both ends of the cylindrical shell physical model are excited; wherein the excitation applied to the cylindrical shell physical model is displacement excitation and force excitation. In this embodiment, the frequency response is expressed as:

[0102] ;

[0103] in, , , Respectively indicate along , , The magnitude of the acceleration of the axis, represents the reference acceleration value, and .

[0104] Through the above settings, by exciting the middle and both ends of the cylindrical shell physical model, it is possible to effectively avoid excitation at the vibration node position, so as to prevent certain modes of the structure from being unable to be excited, and ensure that all modes can be excited.

[0105] According to an embodiment of the present invention, in step S7, in the step of constructing an optimization model for a cylindrical shell physical model based on the optimization parameter group, distribution law and frequency response, the optimization model is expressed as:

[0106] ;

[0107] ;

[0108] ;

[0109] in, Indicates the initial parameters preset by the optimization parameter group. is the matrix used to represent the linear inequality constraints, is the matrix used to represent the linear inequality constraints, is the matrix used to represent the equality constraints, is the matrix used to represent the equality constraints, is the lower limit constraint of the structural parameters of the superstructure unit, is the upper limit constraint of the structural parameters of the superstructure unit, , , is the lower limit of the structural parameter of the superstructure unit, , , is the upper limit of the structural parameter of the superstructure unit, represents the fitness function value, f It represents the optimized frequency range, i.e., the resonance frequency band of the cylindrical shell containing the superstructure unit, fval represents the return value of the fitness function during the optimization process, and fmincon represents the optimization algorithm.

[0110] Furthermore, in step S7, based on the optimization model and with the minimum vibration amplitude as the goal, the optimal solution of the structural parameters in the optimization parameter group is determined to achieve local oscillator optimization for cylindrical shell vibration reduction. In this embodiment, the optimization algorithm used in the iterative optimization step is selected from genetic algorithm, random forest algorithm, ant colony algorithm, etc., thereby, by establishing an interface between the finite element software and the external optimization model (i.e., optimization algorithm), the iterative optimization of the structural parameters of the super-structure unit in the cylindrical shell physical model can be performed to achieve broadband vibration reduction of the cylindrical shell. In this embodiment, the optimization algorithm adjusts the dynamic equation based on the structural parameters in the solved optimization parameter group during the iterative optimization process, so that the corresponding vibration response curve can be obtained by solving the dynamic equation, thereby executing the iterative process with the minimum vibration amplitude as the goal to obtain the optimal solution.

[0111] Furthermore, in order to speed up convergence, a mapping function can be introduced into the optimization model at the same time. The mapping function is expressed as:

[0112] ;

[0113] in, is the target vibration attenuation amplitude, is the transformation factor; where the fitness function value in the optimization process is With target attenuation value After comparison, different mapping values ​​are taken to focus on the values ​​less than the target attenuation value. structure is optimized.

[0114] like Figure 7 As shown in the figure, it is a schematic diagram of the optimized structure of the superstructure unit, and each group of units shows different structural parameters. In order to more intuitively reflect the optimization effect, Figure 8 As shown, the frequency responses of the optimization results and the control group are plotted; wherein, the control group adopts a cylindrical shell with the same parameters (mass and size) as the aforementioned cylindrical shell but without any vibration reduction structure; it can be seen that the vibration is greatly attenuated, and there is an attenuation of about 30 dB in the analysis frequency band, which proves the effectiveness of the optimization method of the present invention.

[0115] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0116] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A local oscillator optimization design method for cylindrical shell vibration reduction, characterized in that: The following steps are involved: S1. constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, and obtaining a dynamic equation of the cylindrical shell physical model to determine a resonant frequency band of the cylindrical shell including the superstructure unit; wherein the cylindrical shell is provided with reinforcing ribs, and the superstructure unit is periodically arranged on the inner side of the cylindrical shell; S2. Divide the super structure unit into multiple super structure unit groups according to preset rules; S3. Determine the structural parameters for influencing the resonance frequency of the superstructure unit, and construct an optimization parameter group for all the superstructure unit groups based on the structural parameters; S4. Based on the structural parameters, determining the resonance frequency of one of the superstructure unit groups, wherein the determined resonance frequency of the superstructure unit group is the first resonance frequency when the cylindrical shell is in a bare shell state; S5. constructing a distribution law of resonance frequencies between the plurality of superstructure unit groups; S6. Adding material parameters to the cylindrical shell physical model and exciting a preset position of the cylindrical shell physical model to pick up a frequency response of the outer surface of the cylindrical shell physical model; S7. constructing an optimization model for the cylindrical shell physical model based on the optimization parameter group, the distribution law and the frequency response, and determining the optimal solution of the structural parameters in the optimization parameter group based on the optimization model and with the goal of minimizing the vibration amplitude, so as to achieve local oscillator optimization for cylindrical shell vibration reduction; In step S1, in the step of obtaining the dynamic equation of the cylindrical shell physical model, the dynamic equation is expressed as: in, represents the mass matrix, , and denote the acceleration, velocity and displacement vector of the cylindrical shell, respectively. represents the damping matrix, represents the stiffness matrix, represents the mechanical load vector acting on the superstructure element, , , …, denote the mass of the superstructure unit, , , …, are the damping factors of the superstructure unit, , , …, They represent the stiffness of the superstructure unit, , , …, denote the load excitation acting on the superstructure unit, represents the number of superstructure units; In step S2, in the step of dividing the super-structure unit into a plurality of super-structure unit groups according to a preset rule, each super-structure unit group includes a plurality of super-structure units, and the structural parameters of the plurality of super-structure units in the same super-structure unit group are consistent; The preset rule is: along the axial direction of the cylindrical shell physical model, multiple superstructure units in the same annular area are divided into a group; or along the circumferential direction of the cylindrical shell physical model, multiple superstructure units in the same arc area are divided into a group.

2. The local oscillator optimization design method according to claim 1, characterized in that: In step S1, in the step of constructing a cylindrical shell physical model of a cylindrical shell including a superstructure unit, the superstructure unit includes: a rubber part and a mass part; The rubber part and the mass part are fixedly connected to each other; The surface of the rubber part away from the mass part is arranged to match the inner side surface of the cylindrical shell; The rubber part and the mass part have the same width and curvature.

3. The local oscillator optimization design method according to claim 2, characterized in that: The natural frequency of the superstructure unit is expressed as: in, is the natural frequency of the superstructure unit, is the equivalent mass of the superstructure unit, is the equivalent stiffness of the superstructure unit, subscript is the serial number of the superstructure unit.

4. The local oscillator optimization design method according to claim 3, characterized in that: In step S3, the structural parameters for influencing the resonance frequency of the superstructure unit are determined, and based on the structural parameters, the optimization parameter group of all the superstructure unit groups is constructed. The structural parameters include: the thickness of the rubber part of the rubber part; , the mass portion thickness of the mass portion , the unit arc length of the superstructure unit ; The optimization parameter group of the super structure unit group is expressed as: in, , , represents the structural parameters of the superstructure unit in the first group of superstructure units, , , represents the structural parameters of the superstructure unit in the second group of superstructure units, , , Indicates Group superstructure unit Structural parameters of the superstructure units in the group.

5. The local oscillator optimization design method according to claim 4, characterized in that: In step S5, in the step of constructing the distribution law of the resonance frequencies between the plurality of superstructure unit groups, the distribution law is that the resonance frequencies of the plurality of superstructure unit groups obey geometric distribution and are expressed as: in, represents the resonant frequency of the first superstructure unit group, represents the resonant frequency of the second superstructure unit group, represents the resonant frequency of the third superstructure unit group, Indicates The resonant frequency of the superstructure unit group, Indicates The resonant frequency of the superstructure unit group, It represents the common ratio of the geometric progression distribution of the resonance frequencies of two adjacent groups of superstructure units, and it is a constant.

6. The local oscillator optimization design method according to claim 5, characterized in that: In step S6, in the step of exciting a preset position of the cylindrical shell physical model to pick up the frequency response of the outer surface of the cylindrical shell physical model, the middle and both ends of the cylindrical shell physical model are excited; The frequency response is expressed as: in, , , Respectively indicate along , , The magnitude of the acceleration of the axis, represents the reference acceleration value, and .

7. The local oscillator optimization design method according to claim 6, characterized in that: In step S7, in the step of constructing an optimization model for the cylindrical shell physical model based on the optimization parameter group, the distribution law and the frequency response, the optimization model is expressed as: in, Indicates the initial parameters preset by the optimization parameter group. is the matrix used to represent the linear inequality constraints, is the matrix used to represent the linear inequality constraints, is the matrix used to represent the equality constraints, is the matrix used to represent the equality constraints, is the lower limit constraint of the structural parameters of the superstructure unit, is the upper limit constraint of the structural parameters of the superstructure unit, is the lower limit of the structural parameter of the superstructure unit, is the upper limit of the structural parameter of the superstructure unit, represents the fitness function value, represents the optimized frequency range, i.e., the resonant frequency band of the cylindrical shell containing the superstructure unit.

8. The local oscillator optimization design method according to claim 7, characterized in that: The superstructure unit is a cubic arc structure; the rubber part and the mass part in the superstructure unit are vulcanized and connected.

Images