Method and system for determining equivalent material parameters of structural acoustic covering layer

Abstract

The invention relates to a method and a system for determining equivalent material parameters of a structural acoustic covering layer. The method comprises the following steps: S1, setting acoustic characteristic requirements of the structural acoustic covering layer, setting value ranges and constraint conditions corresponding to the equivalent material parameters of the structural acoustic covering layer, and setting initial values of the equivalent material parameters; s2, based on the current value of the equivalent material parameter, calculating a sound characteristic parameter meeting a value range and a preset constraint condition by adopting a transfer matrix method; s3, judging whether the sound characteristic parameters meet sound characteristic requirements or not; if yes, current equivalent material parameters are output; otherwise, the equivalent material parameters are adjusted according to the constraint conditions within the preset range, and the step S2 is executed after adjustment. According to the numerical inversion method for the equivalent material parameters of the structural acoustic covering layer, the problem of simulation forecasting of the inhibition effect of the acoustic covering layer on active detection of the target is solved, and the forecasting technology for evaluating the efficiency of the structural acoustic covering layer is improved.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic covering layers, and in particular to a method and system for determining equivalent material parameters of a structural acoustic covering layer. Background Art

[0002] At present, when studying structural acoustic covering layers, the structural acoustic covering layers are usually equivalent to uniform multi-layer covering layers. The thickness, Young's modulus, Poisson's ratio, density and other parameters of the multi-layer covering layers are equivalent material parameters. By studying the equivalent material parameters, the acoustic characteristics of the structural acoustic covering layers can be studied. Therefore, it is necessary to provide a solution that can study the equivalent material parameters of the structural acoustic covering layers. Summary of the invention

[0003] In order to solve the above technical problem or at least partially solve the above technical problem, the present invention provides a method and system for determining equivalent material parameters of a structural acoustic cover layer.

[0004] In a first aspect, the present invention provides a method for determining equivalent material parameters of a structural acoustic cover layer, comprising:

[0005] S1. Setting acoustic characteristic requirements of the structural acoustic covering layer, setting value ranges and constraints corresponding to equivalent material parameters of the structural acoustic covering layer, and setting initial values ​​of the equivalent material parameters;

[0006] S2. Based on the current value of the equivalent material parameter, the transfer matrix method is used to calculate the acoustic characteristic parameter that satisfies the value range and the preset constraint condition;

[0007] S3, judging whether the acoustic characteristic parameters meet the acoustic characteristic requirements;

[0008] If yes, output the current equivalent material parameters;

[0009] Otherwise, the equivalent material parameters are adjusted within the preset range according to the constraint conditions, and the process returns to S2 after the adjustment.

[0010] In a second aspect, the present invention provides a system for determining equivalent material parameters of a structural acoustic cover layer, comprising:

[0011] A data setting module, used to execute S1, set the acoustic characteristic requirements of the structural acoustic covering layer, set the value range and constraint conditions corresponding to the equivalent material parameters of the structural acoustic covering layer, and set the initial value of the equivalent material parameters;

[0012] A parameter calculation module, used to execute S2, based on the current value of the equivalent material parameter, calculate the acoustic characteristic parameter that satisfies the value range and the preset constraint condition by using a transfer matrix method;

[0013] A parameter judgment module is used to execute S3 and judge whether the acoustic characteristic parameters meet the acoustic characteristic requirements; if so, output the current equivalent material parameters; otherwise, adjust the equivalent material parameters according to the constraint conditions within the preset range, and return to the parameter calculation module to execute S2 after adjustment.

[0014] The method and system for determining equivalent material parameters of a structural acoustic covering layer provided by the present invention first set the acoustic characteristic requirements of the structural acoustic covering layer, the value range of the equivalent material parameters, the constraint conditions and the initial value, then calculate the acoustic characteristic parameters based on the initial value, and judge whether the calculated acoustic characteristic parameters meet the acoustic characteristic requirements. If not, adjust the parameters and continue to iterate until the acoustic characteristic requirements are met, and obtain the equivalent material parameters that meet the acoustic characteristic requirements. It can be seen that the present invention proposes a numerical inversion method for equivalent material parameters of a structural acoustic covering layer, which solves the problem of simulation prediction of the suppression effect of the acoustic covering layer on active target detection, and improves the prediction technology for evaluating the effectiveness of the structural acoustic covering layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0017] Figure 1a and 1b It is a schematic flow chart of a method for determining equivalent material parameters of a structural acoustic covering layer in an embodiment of the present invention;

[0018] Figure 2a is a schematic diagram of a structural acoustic covering layer in an embodiment of the invention;

[0019] Figure 2b Schematic diagram of an equivalent multi-layer covering layer in an embodiment of the invention;

[0020] Figure 3a A schematic diagram of the relationship between the structural acoustic cover layer and the incident sound wave in an embodiment of the invention;

[0021] Figure 3b A schematic diagram of the periodic distribution of the computing units in an embodiment of the invention;

[0022] Figure 3cis a spatial schematic diagram of incident sound waves in an embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of a computing unit in an embodiment of the present invention;

[0024] Figure 5 It is a schematic diagram comparing the reflection coefficients when the structural acoustic covering layer is divided into one layer and four layers in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In a first aspect, the present invention provides a method for determining equivalent material parameters of a structural acoustic cover layer, such as Figure 1a and 1b As shown, the method comprises the following steps:

[0027] S1. Setting acoustic characteristic requirements of the structural acoustic covering layer, setting value ranges and constraints corresponding to equivalent material parameters of the structural acoustic covering layer, and setting initial values ​​of the equivalent material parameters;

[0028] It is understandable that the parameters reflecting the acoustic characteristics of the structural acoustic covering layer may include reflection coefficient, transmission coefficient, absorption coefficient, etc. In this solution, the reflection coefficient and transmission coefficient may be specifically used. Before executing this solution, the measured values ​​of the acoustic characteristic parameters may be obtained by measurement, and then the structural acoustic covering layer may be equivalent through this solution, and then the acoustic characteristic parameters may be calculated based on the equivalent structure. If the calculated acoustic characteristic parameters are close to the measured acoustic characteristic parameters, it means that the values ​​of the equivalent material parameters in the equivalent structure are also reasonable. Therefore, in the specific implementation, the acoustic characteristic requirements may include: the difference between the calculated acoustic characteristic parameters and the measured acoustic characteristic parameters is less than the preset value; the acoustic characteristic parameters may include reflection coefficient and transmission coefficient.

[0029] When studying structural acoustic covering layers, they can be equivalent to multiple uniform covering layers, called equivalent multi-layer covering layers, for example, Figure 2a The structural acoustic covering layer can be equivalent to Figure 2bThe illustrated four-layer covering layer. The thickness of each layer in the equivalent multi-layer covering layer and the Young's modulus, Poisson's ratio, density and other parameters of each layer can be used as equivalent material parameters. Each parameter has a corresponding range of values, and after a large number of experimental studies, it is believed that the equivalent material parameters of each layer are easier to achieve the acoustic characteristics requirements when certain parameter gradient requirements are met. The parameter gradient requirements here can be understood as constraints.

[0030] In a specific implementation, the constraint conditions may include: the impedance of the first layer of the equivalent multi-layer covering layer corresponding to the structural acoustic covering layer matches the water impedance, and the loss factor of the first layer is determined by the high-frequency reflection coefficient; the sound velocity of each layer gradually decreases with the frequency; the loss factor of each layer gradually increases with the frequency; the impedance of each layer changes monotonically at the same frequency. Among them, the high-frequency reflection coefficient is the reflection coefficient corresponding to the sound wave of the preset high-frequency frequency, and the loss factor of the first layer is determined by the reflection coefficient.

[0031] It is understandable that, in this step, an initial value is set for the equivalent material parameter within the value range of the equivalent material parameter to participate in subsequent steps.

[0032] S2. Based on the current value of the equivalent material parameter, the transfer matrix method is used to calculate the acoustic characteristic parameter that satisfies the value range and the preset constraint condition;

[0033] In specific implementation, S2 may specifically include the following steps:

[0034] S21, dividing the structural acoustic cover layer into calculation units that are periodically distributed and infinitely extended along the x and y directions;

[0035] In order to facilitate calculation and description, the structural acoustic cover layer can be divided into multiple calculation units in the x-direction and the y-direction. In this way, the calculation units are periodically distributed and infinitely extended in the x-direction and the y-direction. The calculation unit becomes the smallest unit representing the structural acoustic cover layer. According to the Bloch theory, the calculation range is reduced to a finite area. The wave system expansion is used outside the calculation unit, and the single moment method is used to construct the basis function within the calculation unit. Then, the finite element method is used to solve the basis function to obtain the acoustic characteristic parameters.

[0036] The acoustic cover material is a viscoelastic material, see Figure 3b , the computational units are periodically distributed in the x and y directions and extend infinitely, and the intervals between adjacent computational units are a and b respectively. Figure 3a , unit simple harmonic plane wave p in The incident wave is in water, the wave number is k, and the time factor e is ignored jωt See also Figure 3c, the angle between the incident direction of the sound wave and the z-axis is θ, and the angle between the projection of the incident direction of the sound wave on the xy plane and the x-axis is

[0037] Since the calculation units are distributed periodically in the x and y directions and extend infinitely, according to the Bloch theory of periodic physical fields, the sound pressure or displacement function F can be expressed as follows to represent the periodic relationship between the calculation units:

[0038]

[0039] S22, using the basis function cluster of the upper interface and the basis function cluster of the lower interface of the computing unit to construct a basis function of any point in the computing unit, and constructing boundary conditions of each order component of the basis function; wherein the basis function is used to represent the sound pressure field or displacement field of the arbitrary point; the upper interface is the interface where the upper layer of the computing unit contacts water, and the lower interface is the interface where the lower layer of the computing unit contacts water;

[0040] For a computing unit, such as Figure 4 As shown, the space is divided into three regions in the z-axis direction. Regions I and III are semi-infinite media, and region II is a computing unit in the cover layer. The upper interface of the computing unit is S ab , the lower interface is S und , the four sides of the computing unit are S1, S2, S3, and S4.

[0041] For region I (hereinafter referred to as the first region), there are incident waves and reflected waves. The reflected waves are expanded into the form of Fourier series. The total sound field corresponding to the first region can be expressed as:

[0042]

[0043] For region III (hereinafter referred to as the third region), there is only a transmitted wave, so the total sound field in the third region can be expressed as:

[0044]

[0045] In the above formula, m and n are the orders, p in is the acoustic field of the incident wave, p s is the sound field of the reflected wave, p t is the transmitted wave acoustic field, k mn 2 =|k| 2 -(2mπ / a+k x ) 2 -(2nπ / b+k y ) 2 , V mnis the amplitude of the (m,n)th order reflected wave, T mn is the amplitude of the (m,n)th order transmitted wave.

[0046] For region II, define the basis function cluster In the fluid medium, it is the acoustic pressure field p, in the elastic medium, it is the displacement field u, and the upper interface S of the calculation unit is ab With the following interface S und The boundary conditions are different. To ensure the completeness of the basis function, the basis function cluster is expressed as:

[0047]

[0048] Among them, the basis function cluster of the upper interface Basis function cluster of the lower interface The field ψ (sound pressure field or displacement field) at any point in the calculation unit is the (m, n)th order component of the corresponding basis function cluster, which can be expressed by the basis function:

[0049]

[0050] Where ψ(x, y, z) is the basis function corresponding to the point with coordinates (x, y, z) in the calculation unit. is the (m, n)th order component in the basis function cluster of the upper interface, is the (m, n)th order component in the basis function cluster of the lower interface, for The expansion coefficient of for The expansion coefficient of .

[0051] It can be seen that the sound pressure field p, displacement field u and can all be expressed using the above basis functions.

[0052] Wherein, each basis function component satisfies the Helmholtz equation and boundary conditions. If the calculation unit is divided into four layers from top to bottom, the boundary conditions of each order component of the basis function may include the following formula:

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] In the formula, S ab is the upper interface, k mn 2 =|k| 2 -(2mπ / a+k x ) 2 -(2nπ / b+k y ) 2 , The magnitude of k is the wave number of the sound wave, the direction is the incident direction of the sound wave, and θ is the angle between the incident direction of the sound wave and the z-axis. is the angle between the projection of the incident direction of the sound wave on the xy plane and the x-axis; a is the distance between adjacent calculation units in the x-axis direction, and b is the distance between adjacent calculation units in the y-axis direction; S und is the lower interface; S 1 , S 2 , S 3 , S 4 are four sides of the computing unit.

[0062] S23, constructing a first boundary condition corresponding to the continuous node pressure and a second boundary condition corresponding to the continuous particle normal vibration velocity for the upper interface and the lower interface of the calculation unit;

[0063] It can be understood that the upper and lower interfaces of the calculation unit satisfy the continuity of node sound pressure and particle normal velocity. The boundary condition for node sound pressure continuity is the first boundary condition, and the boundary condition for particle normal velocity continuity is the second boundary condition:

[0064] Wherein, the first boundary condition may include:

[0065]

[0066]

[0067] Among them, since both sides of the upper and lower interfaces are the same medium, the particle normal continuity is equivalent to the inverse continuity of the pressure, so the second boundary condition can include:

[0068]

[0069]

[0070] In the formula, R ab For S ab The set of midplane nodes; R und For S und The set of midplane nodes; pt is the transmitted wave acoustic field corresponding to the third region located above the upper interface, p in is the incident wave acoustic field in the first region below the lower interface, p s It is a reflected wave acoustic field in a first region below the lower interface, and the acoustic wave is incident from the first region below the lower interface.

[0071] S24, construct finite element formulations for coupling fluid and elastic body;

[0072] In a specific implementation, the finite element formula may include:

[0073]

[0074] Where ω is the angular frequency, ρ L is the density of the fluid, K L is the stiffness matrix of the fluid, M L is the mass matrix of the fluid, K S is the stiffness matrix of the viscoelastic body, M S is the mass matrix of the viscoelastic body, L 耦合 is the coupling matrix between the viscoelastic body and the fluid; u is the displacement matrix in the viscoelastic body field, p is the pressure vector in the fluid field, Q S is the node load matrix vector of the viscoelastic body, Q L is the nodal load matrix vector for the fluid.

[0075] Among them, u and p can be expressed by the above-mentioned basis function ψ.

[0076] S25, solving the basis function and the finite element formula according to the boundary conditions of the components of each order, the first boundary condition and the second boundary condition, to obtain the reflected wave amplitude and the transmitted wave amplitude of each order of each layer in the calculation unit;

[0077] It can be understood that p and u in the finite element formula are expressed by the above-mentioned basis function ψ, and then the finite element formula is solved, and the solution process is constrained by the boundary conditions, first boundary conditions and second boundary conditions of each order component in the basis function, so as to obtain the amplitude V of each order plane wave mn 、T mn , in fact, the coefficients of the basis function can also be calculated at the same time

[0078] S26, calculating the reflection coefficient of each layer according to the amplitude of the reflected wave of each order of each layer; calculating the transmission coefficient of each layer according to the amplitude of the transmitted wave of each order of each layer;

[0079] In a specific implementation, the calculation formula of the reflection coefficient of each layer may include:

[0080]

[0081] In a specific implementation, the calculation formula of the transmission coefficient of each layer may include:

[0082]

[0083] Where V mn is the (m, n)th order reflection wave amplitude of each layer, T mn is the (m, n)th order transmission wave amplitude of each layer, V is the reflection coefficient of each layer, and T is the transmission coefficient of each layer.

[0084] At this point, the acoustic characteristic parameters of each layer are obtained.

[0085] S27, constructing a third boundary condition corresponding to the continuity of pressure and the continuity of particle velocity between the layers according to the current value of the equivalent material parameters of each layer and the projection coefficient and reflection coefficient of each layer;

[0086] It is understandable that the third boundary condition is constructed according to the current values ​​of the equivalent material parameters of each layer and the acoustic characteristic parameters, and the third boundary condition reflects the pressure continuity characteristics between the layers and the particle vibration velocity continuity characteristics between the layers.

[0087] S28, according to the third boundary condition, the transfer matrices of each layer are connected to obtain a total transfer matrix;

[0088] S29. Calculate the corresponding total input impedance according to the total transfer matrix; and calculate the reflection coefficient and projection coefficient of the calculation unit according to the total input impedance.

[0089] It is understandable that the calculation process of the transmission parameters is similar, and the acoustic characteristic parameters are calculated at this point.

[0090] It can be seen that after calculating the acoustic characteristic parameters of each layer, according to the boundary conditions corresponding to the node pressure continuity and particle vibration velocity continuity between the layers, the transfer matrices of each layer are connected according to the boundary conditions to obtain the total transfer matrix of the multilayer structure. The input impedance of the entire layer system is obtained from the boundary conditions of the interface on the last semi-infinite medium, and thus the acoustic characteristic parameters of the entire layer system can be obtained.

[0091] For example, the general process of S27 to S29 can be seen in the following flow:

[0092] Taking the nth layer as an example, the transfer matrix in the fluid and elastic medium layer is given. The thickness and density of the layer are d (n) and ρ (n) The subscripts S and T denote the fluid and elastomeric media, respectively.

[0093] If the nth layer is a fluid medium, there are longitudinal waves propagating in the positive z direction and longitudinal waves propagating in the negative z direction in the layer, and the corresponding potential function can be expressed as:

[0094]

[0095] The sound pressure in the layer p (n) , normal vibration velocity υ z (n) The relationship with the potential function is as follows:

[0096]

[0097] According to the above formula, for the upper interface of the nth layer, z = d (n) , (omit factors ),have:

[0098]

[0099] The lower interface of the nth layer, i.e. z=0, has:

[0100]

[0101] In the formula, the superscript (n+) and (n-) Respectively represent the values ​​of the physical quantity at the upper and lower interfaces of the nth layer of the medium. According to the continuity conditions of the upper and lower interfaces, we can get:

[0102]

[0103] In the formula, A S (n) is the transfer matrix of the fluid medium.

[0104] If the nth layer is an elastic medium, there are longitudinal waves and transverse waves propagating in the positive z and negative z directions respectively, and the corresponding potential function is:

[0105]

[0106] ψ=(ψ'e jβz +ψ"e -jβz ) j(σx-ωt)

[0107] Where σ = k x =κ x , k and κ are the longitudinal and transverse wave numbers respectively.

[0108] The velocity component of a particle at any point in the layer is:

[0109] υ y =0,

[0110] The stress tensor components are:

[0111] σ y =0,

[0112] Among them, μ and λ are Lamé constants, u x 、u z is the displacement component:

[0113]

[0114] From the above expression, we can find υ x ,υ z , σ x and σ z .

[0115] When z=d, we can get:

[0116]

[0117] The coefficient matrix on the right side of the equation is denoted as A 4 (n) . When z=0, we have:

[0118]

[0119] We can get:

[0120]

[0121] The coefficient matrix on the right side of the equation is denoted as B 4 (n) , thus:

[0122]

[0123] A T (n) is the transfer matrix of the elastic medium.

[0124] When solving the reflection coefficient, you need to determine the initial matrix first. If medium 1 is a fluid, then:

[0125]

[0126] If the medium is an elastic body:

[0127]

[0128] In the formula, D represents the independent variable matrix, M (n) =A (n) ·M (n-1) , A (n)is the transfer matrix.

[0129] If the incident medium n+1 is a semi-infinite fluid medium, at its lower interface:

[0130]

[0131] A is the transfer matrix of the fluid or elastic medium.

[0132] The total input impedance can be calculated as:

[0133]

[0134] Note: Impedance = sound pressure / vibration speed, because is the independent variable matrix, and after division and elimination, the impedance can be expressed as a matrix The (1,1)th order variable is divided by the (2,1)th order variable.

[0135] Thus, the reflection coefficient V can be obtained:

[0136]

[0137] Among them, Z (n+1) =ρ (n+1) c (n+1) / cosθ (n+1) .

[0138] S3, judging whether the acoustic characteristic parameters meet the acoustic characteristic requirements;

[0139] If yes, output the current equivalent material parameters;

[0140] Otherwise, the equivalent material parameters are adjusted within the preset range according to the constraint conditions, and the process returns to S2 after the adjustment.

[0141] It is understandable that if the calculated acoustic characteristic parameters meet the acoustic characteristic requirements, it means that the equivalent material parameters at this time meet the requirements of the equivalent covering layer, and the equivalent material parameters at this time can be used as the final equivalent material parameters to exit the iteration process. If the calculated acoustic characteristic parameters do not meet the acoustic characteristic requirements, it means that the equivalent material parameters at this time do not meet the requirements of the equivalent covering layer, and need to be adjusted based on the current values, and then enter the next iteration process after the adjustment.

[0142] It is understandable that the present invention, based on the acoustic properties of the actual covering layer, equates the covering layer to a uniform viscoelastic medium, and uses a parameter matching search method to obtain the thickness of each layer and the equivalent density, Young's modulus, loss factor, Poisson's ratio and other parameters of each layer according to the acoustic property requirements. In other words, based on the acoustic parameters of the acoustic covering layer measured in a laboratory sound tube, constructing a multilayer covering layer with similar acoustic properties is an inverse problem. The parameters of each layer in the acoustic covering layer are obtained using a parameter matching search method according to the control requirements of the acoustic properties. The present invention can construct an acoustic covering layer with a multilayer structure whose acoustic properties are similar in a single frequency or a wide frequency band, and obtain an equivalent characterization method of the acoustic covering layer in the problem of low-frequency sound scattering using equivalent material parameters.

[0143] It is understandable that the present invention adopts the finite element method to solve the basis function, because the finite element method can solve any boundary problem and the sound propagation mechanism is clear.

[0144] It is understandable that the value range of each equivalent material parameter is set according to the laws of physics, and the equivalent material parameters must meet certain conditions, such as the change law of loss factor, the change law of impedance, etc. Parameters that meet the conditions are searched according to the value range and constraints, and then it is determined whether the acoustic characteristic parameters calculated at this time can meet the acoustic characteristic requirements. If not, further corrections are made based on the current values ​​of each parameter. Through continuous corrections, parameters that meet the acoustic characteristic requirements are finally obtained.

[0145] It is understandable that the present invention is based on the theoretical prediction model of the low-frequency acoustic target intensity laminate of the elastic shell with the acoustic covering layer, and proposes a numerical inversion method for the equivalent material parameters of the structural acoustic covering layer. One of the key points of the present invention is the numerical inversion method for the equivalent material parameters of the structural acoustic covering layer proposed in combination with the target low-frequency acoustic target intensity simulation technology for laying the acoustic covering layer, which is a key element necessary for predicting the target low-frequency acoustic target intensity for laying the acoustic covering layer. The numerical inversion method for the equivalent material parameters of the structural acoustic covering layer provided by the present invention solves the problem of simulation prediction of the suppression effect of the structural acoustic covering layer on active target detection, and improves the prediction technology for evaluating the effectiveness of the structural acoustic covering layer.

[0146] The present invention matches the material parameters of the covering layer according to the gradient requirements (i.e., constraints) of the uniform multi-layer acoustic covering layer, the value range, and the acoustic characteristic requirements of the acoustic covering layer. For example, the covering layer material is divided into one layer and four layers respectively, and the material parameters of each layer are obtained by using the parameter matching method according to the requirements of the reflection characteristics. The comparison of the reflection coefficient of the anechoic tile in the case of one layer and four layers can be seen in Table 1 below. Figure 5 The results show that the equivalent material parameters that meet the requirements of structure-borne acoustic characteristics control can be obtained by using parameter matching technology. The range of material parameters that meet the requirements is different for different backing structures.

[0147] Table 1. Equivalent material parameters for 1 layer and 4 layers

[0148]

[0149] In a second aspect, the present invention provides a system for determining equivalent material parameters of a structural acoustic cover layer, comprising:

[0150] A data setting module, used to execute S1, set the acoustic characteristic requirements of the structural acoustic covering layer, set the value range and constraint conditions corresponding to the equivalent material parameters of the structural acoustic covering layer, and set the initial value of the equivalent material parameters;

[0151] A parameter calculation module, used to execute S2, based on the current value of the equivalent material parameter, calculate the acoustic characteristic parameter that satisfies the value range and the preset constraint condition by using a transfer matrix method;

[0152] A parameter judgment module is used to execute S3 and judge whether the acoustic characteristic parameters meet the acoustic characteristic requirements; if so, output the current equivalent material parameters; otherwise, adjust the equivalent material parameters according to the constraint conditions within the preset range, and return to the parameter calculation module to execute S2 after adjustment.

[0153] It is understandable that the explanations, examples, specific implementation methods, beneficial effects, etc. of the relevant contents in the system provided in this aspect can be referred to the corresponding contents in the first aspect and will not be repeated here.

[0154] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0155] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0156] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as RON / RAN, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0157] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for determining equivalent material parameters of a structural acoustic covering layer, characterized in that: include: S1. Setting acoustic characteristic requirements of the structural acoustic covering layer, setting value ranges and constraints corresponding to equivalent material parameters of the structural acoustic covering layer, and setting initial values ​​of the equivalent material parameters; S2. Based on the current value of the equivalent material parameter, the transfer matrix method is used to calculate the acoustic characteristic parameter that satisfies the value range and the preset constraint condition; S3, judging whether the acoustic characteristic parameters meet the acoustic characteristic requirements; If yes, output the current equivalent material parameters; Otherwise, the equivalent material parameters are adjusted within the preset range according to the constraint conditions, and the process returns to S2 after the adjustment.

2. The method according to claim 1, characterized in that The constraint conditions include: the impedance of the first layer of the equivalent multi-layer covering layer corresponding to the structural acoustic covering layer matches the water impedance, and the loss factor of the first layer is determined by the high-frequency reflection coefficient; the sound velocity of each layer gradually decreases with the frequency; the loss factor of each layer gradually increases with the frequency; the impedance of each layer changes monotonically at the same frequency.

3. The method according to claim 1, characterized in that The acoustic characteristic requirement includes: a difference between a calculated acoustic characteristic parameter and a measured acoustic characteristic parameter is less than a preset value; and the acoustic characteristic parameters include a reflection coefficient and a transmission coefficient.

4. The method according to claim 1, characterized in that: The method of calculating the acoustic characteristic parameters satisfying the value range and the preset constraint conditions based on the current value of the equivalent material parameter by using the transfer matrix method includes: Dividing the structural acoustic cover layer into calculation units that are periodically distributed and infinitely extended along the x and y directions; The basis function cluster of the upper interface and the basis function cluster of the lower interface of the calculation unit are used to construct the basis function of any point in the calculation unit, and the boundary conditions of each order component of the basis function are constructed; wherein the basis function is used to represent the sound pressure field or displacement field of the arbitrary point; the upper interface is the interface where the upper layer of the calculation unit contacts water, and the lower interface is the interface where the lower layer of the calculation unit contacts water; Constructing a first boundary condition corresponding to the node pressure continuity and a second boundary condition corresponding to the particle normal velocity continuity for the upper interface and the lower interface of the calculation unit; Construct finite element formulations for coupling fluids and elastic bodies; Solving the basis function and the finite element formula according to the boundary conditions of the components of each order, the first boundary condition and the second boundary condition to obtain the reflected wave amplitude and the transmitted wave amplitude of each order of each layer in the calculation unit; Calculate the reflection coefficient of each layer according to the amplitude of the reflected wave of each order of each layer; calculate the transmission coefficient of each layer according to the amplitude of the transmitted wave of each order of each layer; According to the current values ​​of the equivalent material parameters of each layer and the projection coefficient and reflection coefficient of each layer, a third boundary condition corresponding to the pressure continuity and particle vibration velocity continuity between the layers is constructed; According to the third boundary condition, the transfer matrices of each layer are connected to obtain a total transfer matrix; According to the total transfer matrix, the corresponding total input impedance is calculated; and according to the total input impedance, the reflection coefficient and the projection coefficient of the calculation unit are calculated.

5. The method according to claim 4, characterized in that The basis functions of any point in the computing unit include: Where ψ(x, y, z) is the basis function corresponding to the point with coordinates (x, y, z) in the calculation unit, is the (m, n)th order component in the basis function cluster of the upper interface, is the (m, n)th order component in the basis function cluster of the lower interface, for The expansion coefficient of for The expansion coefficient of .

6. The method according to claim 5, characterized in that If the calculation unit is divided into four layers from top to bottom, correspondingly, the boundary conditions of each order component of the basis function include: In the formula, S ab is the upper interface, k mn 2 =|k| 2 -(2mπ / a+k x ) 2 -(2nπ / b+k y ) 2 , The magnitude of k is the wave number of the sound wave, the direction is the incident direction of the sound wave, and θ is the angle between the incident direction of the sound wave and the z-axis. is the angle between the projection of the incident direction of the sound wave on the xy plane and the x-axis; a is the distance between adjacent calculation units in the x-axis direction, and b is the distance between adjacent calculation units in the y-axis direction; S und is the lower interface; S1, S2, S3, S4 are the four side surfaces of the computing unit.

7. The method according to claim 5, characterized in that The finite element formula includes: Where ω is the angular frequency, ρ L is the density of the fluid, K L is the stiffness matrix of the fluid, M L is the mass matrix of the fluid, K S is the stiffness matrix of the viscoelastic body, M S is the mass matrix of the viscoelastic body, L 耦合 is the coupling matrix between the viscoelastic body and the fluid; u is the displacement matrix in the viscoelastic body field, p is the pressure vector in the fluid field, Q S is the node load matrix vector of the viscoelastic body, Q L is the nodal load matrix vector for the fluid.

8. The method according to claim 5, characterized in that The first boundary condition includes: The second boundary condition includes: In the formula, R ab For S ab The set of midplane nodes; R und For S und The set of midplane nodes; p t is the transmitted wave acoustic field corresponding to the third region located above the upper interface, p in is the incident wave acoustic field in the first region below the lower interface, p s It is a reflected wave acoustic field in a first region below the lower interface, and the acoustic wave is incident from the first region below the lower interface.

9. The method according to claim 6, characterized in that: The calculation formula of the reflection coefficient of each layer includes: The calculation formula of the transmission coefficient of each layer includes: Where V mn is the (m, n)th order reflection wave amplitude of each layer, T mn is the (m, n)th order transmission wave amplitude of each layer, V is the reflection coefficient of each layer, and T is the transmission coefficient of each layer.

10. A system for determining equivalent material parameters of a structural acoustic covering layer, characterized in that: include: A data setting module, used to execute S1, set the acoustic characteristic requirements of the structural acoustic covering layer, set the value range and constraint conditions corresponding to the equivalent material parameters of the structural acoustic covering layer, and set the initial value of the equivalent material parameters; A parameter calculation module, used to execute S2, based on the current value of the equivalent material parameter, calculate the acoustic characteristic parameter that satisfies the value range and the preset constraint condition by using a transfer matrix method; A parameter judgment module is used to execute S3 and judge whether the acoustic characteristic parameters meet the acoustic characteristic requirements; if so, output the current equivalent material parameters; otherwise, adjust the equivalent material parameters according to the constraint conditions within the preset range, and return to the parameter calculation module to execute S2 after adjustment.

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