Sound field control calculation method based on gradient phase change of bright spot model

Abstract

The application discloses a sound field regulation and control calculation method based on gradient phase change of bright spot model, relates to the technical field of acoustic metasurface, and comprises the following steps: determining a frequency parameter for sound field regulation and control; calculating a target surface bright spot to determine a main scattering position; arranging an acoustic metasurface at a position with strong scattering to perform regulation and control after the surface bright spot is calculated; verifying whether the result of piecewise superposition is consistent with the result of direct calculation of the piecewise bright spot model by using finite element software or through theoretical solution; if the result is consistent, the piecewise bright spot model method is correct; solving a scattered sound field by using the piecewise bright spot model method and adding phase change; and quickly calculating scattering characteristics of the acoustic metasurface. The sound field regulation and control calculation method based on gradient phase change of bright spot model can regulate the scattered sound field by using the bright spot model method and giving the gradient change phase, and the acoustic metasurface can be quickly calculated by setting a suitable phase.

Description

Technical Field

[0001] This invention relates to the field of acoustic metasurface technology, and in particular to a method for calculating acoustic field modulation based on gradient phase changes of a bright spot model. Background Technology

[0002] Acoustic metasurfaces are a novel type of acoustic metamaterial based on subwavelength dimensions, composed of arrays of metamaterial structural units. They control the wavefront phase of sound waves through the design of microstructural functional units, thereby achieving directional manipulation of reflected or transmitted sound waves. Actual underwater vehicles are quite complex, possessing intricate linear structures such as superstructures, sterns, and rudders. Current acoustic metasurfaces face significant challenges in modeling these complex, convex linear structures.

[0003] When calculating the scattering characteristics of simple structures, the bright spot model method has the advantages of fast calculation speed and accurate calculation results. The piecewise bright spot model method is a further development based on the bright spot model method, which makes the calculation of the scattering characteristics of arbitrary convex structures both fast and accurate.

[0004] The scattering characteristics of acoustic metasurfaces are mainly calculated using the finite element method or the plate element method. However, these two methods are relatively slow. Using the bright spot model method will greatly improve the calculation speed. This method can not only quickly calculate the scattering characteristics of acoustic metasurfaces, but also determine the control phase of the metasurface under actual conditions through calculation. Summary of the Invention

[0005] The purpose of this invention is to provide a sound field control calculation method based on the gradient phase change of the bright spot model, which solves the problems mentioned in the background art, realizes the control of the scattered sound field, and achieves rapid calculation of acoustic metasurfaces by setting an appropriate phase.

[0006] To achieve the above objectives, this invention provides a method for calculating sound field modulation based on gradient phase changes of a bright spot model, comprising the following steps:

[0007] Step S1: For any underwater vehicle, determine the frequency parameters for sound field control;

[0008] Step S2: Take any complex underwater vehicle structure as the target, use the plate element method to calculate the bright spots on the target surface, and decompose it into surface bright spot feature components. By observing the distribution of the bright spots on the target surface, determine the main location of scattering.

[0009] Step S3: After calculating the surface bright spots, acoustic metasurfaces are arranged at the locations with strong scattering to adjust the scattered sound field of the target surface.

[0010] Step S4: Use finite element software or theoretical solutions to verify whether the results of the piecewise superposition are consistent with the results of the direct calculation of the piecewise bright spot model. If they are consistent, the piecewise bright spot model method is correct.

[0011] Step S5: Solve the scattered sound field using the piecewise bright spot model method with phase change;

[0012] Step S6: Calculate the scattered sound field and then assign a corresponding phase to the metasurface or calculate the phase change of the metasurface to quickly calculate the scattering characteristics of the acoustic metasurface.

[0013] Preferably, in step S1, the frequency parameters include the calculated frequency and the step size, wherein the calculated frequency is set to 100Hz to 1000Hz and the step size is set to 10Hz.

[0014] Preferably, step S2 uses the plate element method to calculate the target surface bright spots, specifically including:

[0015] The target is divided into N surface elements, each representing a local region in the medium. The scattered sound field of each surface element is calculated using the plate element method. The model surface mesh is drawn using MATLAB, and the calculated scattered sound field values ​​are assigned to the mesh to obtain the bright spots on the target surface.

[0016] Preferably, step S4 specifically includes:

[0017] The surface bright spot feature is segmented into multiple segmented units. The segmented bright spot model is then used to calculate the values ​​for each segmented unit, and the phases of each segmented unit are superimposed to form the entire segmented bright spot model. Assuming the transfer function of each tiny segmented unit is I... i The transfer function after phase superposition is:

[0018]

[0019] In the formula, δ i Let θ be the phase distance of the i-th unit, θ be the incident angle, j be the imaginary number, k be the wave number, and N be the number of slice units;

[0020] The formula for calculating the target intensity of the entire patch bright spot model is obtained based on the transfer function, as shown below:

[0021]

[0022] In the formula, TS represents the target intensity, N represents the number of slice units, and λ represents the wavelength;

[0023] The accuracy of the target strength is verified through simulation calculations or theoretical formulas.

[0024] Preferably, step S5 specifically includes: assigning a phase to each segment unit, wherein the assigned phase is a phase with gradient changes, so that there are gradient changes between different segment units, thereby controlling the scattered sound field.

[0025] Preferably, the specific steps of step S6 are as follows:

[0026] Step S61: Find the maximum value of the difference between the original target intensity and the modulated target intensity through the objective function, and optimize the phase parameters by combining the genetic algorithm;

[0027] Step S62: Depending on the requirements, change the objective function and optimization parameter settings to obtain the phase change corresponding to the target sound field.

[0028] Preferably, the expression for the objective function in step S61 is as follows:

[0029]

[0030] In the formula, TS 原 TS represents the original target intensity value. 新 denoted by , where f represents the target intensity value after regulation, and f represents the frequency.

[0031] Preferably, the parameters of the genetic algorithm are set in step S62, including: initial population size of 500, crossover rate of 0.5, elite rate of 0.3, maximum number of generations of evolution of 400, and other parameters are all default values.

[0032] Therefore, the present invention adopts the above-mentioned sound field control calculation method based on the gradient phase change of the bright spot model. By using the bright spot model method and assigning a gradient phase change, the scattered sound field can be controlled. By setting an appropriate phase, the acoustic metasurface can be calculated quickly. By using the piecewise bright spot model method for sound field control, not only can the advantages of the fast calculation of the bright spot model be utilized, but the calculation accuracy of the scattering characteristics of complex models can also be improved, and the sound field control effect is obvious.

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating an embodiment of a sound field modulation calculation method based on gradient phase change of a bright spot model according to the present invention.

[0035] Figure 2 This is a surface bright spot distribution diagram of a model when a sound wave is incident at 45°, according to an embodiment of the sound field control calculation method based on the gradient phase change of a bright spot model of the present invention.

[0036] Figure 3This is a surface bright spot distribution diagram of the model when a sound wave is incident at 90°, according to an embodiment of the sound field control calculation method based on the gradient phase change of the bright spot model of the present invention.

[0037] Figure 4 This is a surface bright spot distribution diagram of the model when a sound wave is incident at 120°, according to an embodiment of the sound field control calculation method based on the gradient phase change of the bright spot model of the present invention.

[0038] Figure 5 The diagram shows the segmented bright spot model of the present invention, wherein (a) is a calculation model diagram and (b) is an approximate schematic diagram;

[0039] Figure 6 This is a comparison chart of the target intensity values ​​calculated by the patch bright spot model and empirical formulas in this invention;

[0040] Figure 7 This is a calculation model diagram of the segmented cylindrical shell of the present invention;

[0041] Figure 8 This is a comparison of the target intensity values ​​calculated by the segmented bright spot model of the present invention under two conditions: no phase and phase.

[0042] Figure 9 The following are comparison results of the target intensity values ​​of the present invention: (a) is a comparison of no phase added and phase changing according to π / 9; (b) is a comparison of no phase added and phase changing according to π / 7; (c) is a comparison of no phase added and phase changing according to π / 6; (d) is a comparison of no phase added and phase changing according to π / 5; (e) is a comparison of no phase added and phase changing according to π / 4; and (f) is a comparison of no phase added and phase changing according to π / 3.

[0043] Figure 10 This is a schematic diagram of the ellipsoid segmentation of the present invention;

[0044] Figure 11 The diagram shows the adjustment effect of the segmented highlight model of the present invention at different angles. Detailed Implementation

[0045] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0047] Example

[0048] Please see Figure 1-11 This invention provides a method for calculating sound field modulation based on the gradient phase change of a bright spot model, comprising the following steps:

[0049] Step S1: For any underwater vehicle, determine the frequency parameters for sound field control. The frequency parameters include the calculated frequency and the step size. In this embodiment, the calculated frequency is set to 100Hz to 1000Hz, and the step size is set to 10Hz.

[0050] Step S2: Taking any complex underwater vehicle structure as the target, calculate the bright spots on the target surface using the plate element method, and decompose it into surface bright spot feature components. By observing the distribution of the bright spots on the target surface, determine the main locations of scattering. The calculation of target surface bright spots using the plate element method specifically includes:

[0051] The target is divided into N surface elements, each representing a local region in the medium. The scattered sound field of each surface element is calculated using the plate element method. The model surface mesh is drawn using MATLAB, and the calculated scattered sound field values ​​are assigned to the mesh to obtain the bright spots on the target surface.

[0052] Step S3: After calculating the bright spots on the surface, an acoustic metasurface is placed at the location with strong scattering for manipulation, thereby changing the scattered sound field of the target surface.

[0053] Step S4: Use finite element software or theoretical solutions to verify whether the results of the piecewise superposition are consistent with the results of directly calculating the piecewise bright spot model. If they are consistent, the piecewise bright spot model method is correct.

[0054] Step S5: Solve the scattered sound field using the piecewise bright spot model method with phase change. Assign a phase to each piecewise unit; this phase is a gradient-varying phase, creating gradient changes between different piecewise units, thereby controlling the scattered sound field. Specifically, this includes:

[0055] The surface bright spot feature is segmented into multiple segmented units. The segmented bright spot model is then used to calculate the values ​​for each segmented unit, and the phases of each segmented unit are superimposed to form the entire segmented bright spot model. Assuming the transfer function of each tiny segmented unit is I... i The transfer function after phase superposition is:

[0056]

[0057] In the formula, δ i Let θ be the phase distance of the i-th unit, θ be the incident angle, j be the imaginary number, k be the wave number, and N be the number of slice units;

[0058] The formula for calculating the target intensity of the entire patch bright spot model is obtained based on the transfer function, as shown below:

[0059]

[0060] In the formula, TS represents the target intensity, N represents the number of slice units, and λ represents the wavelength.

[0061] The accuracy of the target strength is verified through simulation calculations or theoretical formulas.

[0062] Step S6: Calculate the scattered sound field and then assign a corresponding phase to the metasurface or calculate the phase change of the metasurface to quickly calculate the scattering characteristics of the acoustic metasurface. The specific steps are as follows:

[0063] Step S61: Find the maximum value of the difference between the original target intensity and the modulated target intensity through the objective function, and optimize the phase parameters by combining the genetic algorithm.

[0064] Step S62: Depending on the requirements, change the objective function and optimization parameter settings to obtain the phase change corresponding to the target sound field.

[0065] The above method will be further explained below with reference to the accompanying drawings of this application.

[0066] Please see below Figure 2-4 , Figure 2 , Figure 3 , Figure 4The figures show the surface bright spot distribution of the model when the sound wave is incident at 45°, 90°, and 120°. The main scattering bright spots are shown in the red box in the figure. The darker the color, the stronger the echo. Therefore, acoustic metasurfaces need to be placed at the bright spot positions in the figure to control the scattering sound field of the strong scattering component, which can change the direction or energy of its scattered echo.

[0067] The location of the acoustic metasurface was determined by surface bright spot calculation, which is the area in the red box in the figure.

[0068] To verify the accuracy of the segmented bright spot model for calculating the cylindrical shell structure, the total length of the cylinder is 42m and the radius is 3.75m. A cross-section of the cylinder is taken, which can be approximated as N infinitesimal cylindrical segments. The bright spot transfer function of the infinitesimal elliptical frustum is assumed to be... The origin O is the reference point for calculating the phase distance. Therefore, the bright spot transfer function considering the phase is:

[0069]

[0070] In the formula, j represents the imaginary part, k represents the wave number, and L i This represents the phase distance, and N represents the number of slice units.

[0071] Finally, the bright spot transfer functions, taking phase into account, are coherently superimposed. The scattered sound field or target intensity of the variable cross-section oblique convex structure is then approximated using the superimposed bright spot transfer functions. The target intensity calculation formula is as follows:

[0072]

[0073] The bright spot transfer function is: It can be calculated using the following formula:

[0074]

[0075] To verify the accuracy of the segmented bright spot model calculation method, the following empirical formula was used when the sound wave was incident transversely:

[0076]

[0077] Where a is the radius and L is the length.

[0078] from Figure 6 The results show that the segmented bright spot model agrees well with the empirical formula and the results of the plate element, proving the reliability of the segmented bright spot model in calculating cylindrical shells.

[0079] When performing phase manipulation on a cylindrical shell structure, a specific phase can be assigned to each segment when using a piecewise bright spot model, resulting in a gradient change in the cylindrical shell structure, such as... Figure 7As shown, the calculation frequency is 100Hz to 1000Hz, and the step size is 10Hz. First, the target intensity comparison is calculated when the phase of the sound wave changes according to π / 8 under normal transverse incidence.

[0080] from Figure 8 The calculation results show that when the sound wave is incident transversely, adding a phase to each micro-cylinder element has a significant effect on reducing the target intensity, with an average reduction of about 18.7 dB.

[0081] The objective function can be defined as finding the maximum value of the difference between the original target intensity and the adjusted target intensity. Since the target intensity in the lateral direction is the maximum in the circumferential angle range, this example only optimizes the lateral direction.

[0082] The objective function is:

[0083]

[0084] In the formula, TS 原 TS represents the original target intensity value. 新 This represents the target intensity value after regulation, where f is the frequency. The parameters for the genetic algorithm are set; different parameter settings affect both the accuracy and speed of the reflection coefficient parameter inversion. The initial population size is 500, crossover rate is 0.5, elite rate is 0.3, maximum number of generations is 400, and other parameters are default values.

[0085] Figure 9 This demonstrates the results of the genetic algorithm optimization process after parameter rounding. Different phase parameters are selected based on varying required reduction amounts. Figure 9 The calculation results show that the effect of adding phase to the cylinder is better as the phase adjustment range increases. When the phase changes by π / 9, the target intensity decreases by an average of 17.39 dB; when the phase changes by π / 7, the target intensity decreases by an average of 20.40 dB; when the phase changes by π / 6, the target intensity decreases by an average of 21.75 dB; when the phase changes by π / 5, the target intensity decreases by an average of 23.46 dB; when the phase changes by π / 4, the target intensity decreases by an average of 25.62 dB; and when the phase changes by π / 3, the target intensity decreases by an average of 28.31 dB.

[0086] When sound waves are incident at a low angle, the bow ellipsoid acts as the primary scatterer. The aforementioned method is used to modulate its scattered sound field. The ellipsoid is segmented as follows: Figure 10 As shown in the figure. After calculation, the effect of controlling the scattered sound field at a low incident angle when the incident frequency is 2000Hz is as follows: Figure 11 As shown.

[0087] The results above demonstrate that using the bright spot model method and assigning a gradient-varying phase allows for the manipulation of the scattered sound field. By setting an appropriate phase, rapid calculations of acoustic metasurfaces can be achieved. Using the piecewise bright spot model method for sound field manipulation not only leverages the fast computational advantage of the bright spot model but also improves the computational accuracy of the scattering characteristics of complex models, resulting in a significant sound field manipulation effect.

[0088] Therefore, the present invention adopts the above-mentioned sound field control calculation method based on the gradient phase change of the bright spot model. By using the bright spot model method and assigning a gradient phase change, the scattered sound field can be controlled. By setting an appropriate phase, the acoustic metasurface can be calculated quickly. By using the piecewise bright spot model method for sound field control, not only can the advantages of the fast calculation of the bright spot model be utilized, but the calculation accuracy of the scattering characteristics of complex models can also be improved, and the sound field control effect is obvious.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for calculating sound field control based on gradient phase change of a bright spot model, characterized in that, Includes the following steps: Step S1: For any underwater vehicle, determine the frequency parameters for sound field control; Step S2: Take any complex underwater vehicle structure as the target, use the plate element method to calculate the bright spots on the target surface, and decompose it into surface bright spot feature components. By observing the distribution of the bright spots on the target surface, determine the main location of scattering. Step S3: After calculating the surface bright spots, acoustic metasurfaces are arranged at the locations with strong scattering to adjust the scattered sound field of the target surface. Step S4: Use finite element software or theoretical solutions to verify whether the results of the piecewise superposition are consistent with the results of the direct calculation of the piecewise bright spot model. If they are consistent, the piecewise bright spot model method is correct. Step S5: Solve the scattered sound field using the piecewise bright spot model method with phase change; Step S6: Calculate the scattered sound field and then assign the corresponding phase to the metasurface or calculate the phase change of the metasurface to quickly calculate the scattering characteristics of the acoustic metasurface; Step S5 specifically includes: assigning a phase to each segment unit, wherein the assigned phase is a phase with gradient changes, so that there are gradient changes between different segment units, thereby controlling the scattered sound field.

2. The sound field control calculation method based on the gradient phase change of the bright spot model according to claim 1, characterized in that: In step S1, the frequency parameters include the calculated frequency and the step size, wherein the calculated frequency is set to 100Hz~1000Hz and the step size is set to 10Hz.

3. The sound field control calculation method based on the gradient phase change of the bright spot model according to claim 2, characterized in that, Step S2 uses the plate element method to calculate the target surface bright spots, specifically including: Divide the target into N Each surface element represents a local region in the medium. The scattered sound field of each surface element is calculated using the plate element method. The model surface mesh is drawn using MATLAB, and the calculated scattered sound field values ​​are assigned to the mesh to obtain the target surface bright spots.

4. The sound field control calculation method based on the gradient phase change of the bright spot model according to claim 3, characterized in that, Step S4 specifically includes: The surface bright spot feature is segmented into multiple segmented units. Each segmented unit is then calculated using the segmented bright spot model, and the phases of all segmented units are superimposed to form the entire segmented bright spot model. Assuming the transfer function of each tiny segmented unit is... The transfer function after phase superposition is: ； In the formula, For the first i Phase distance of each unit, The angle of incidence, represents an imaginary number, Indicates wave number, N Indicates the number of slice units; The formula for calculating the target intensity of the entire patch bright spot model is obtained based on the transfer function, as shown below: ； In the formula, Indicates target intensity. N Indicates the number of slice units. Indicates wavelength; The accuracy of the target strength is verified through simulation calculations or theoretical formulas.

5. The sound field control calculation method based on the gradient phase change of the bright spot model according to claim 4, characterized in that, The specific steps of step S6 are as follows: Step S61: Find the maximum value of the difference between the original target intensity and the modulated target intensity through the objective function, and optimize the phase parameters by combining the genetic algorithm; Step S62: Depending on the requirements, change the objective function and optimization parameter settings to obtain the phase change corresponding to the target sound field.

6. The sound field control calculation method based on the gradient phase change of the bright spot model according to claim 5, characterized in that, The expression for the objective function in step S61 is as follows: ； In the formula, TSoriginal represents the original target intensity value, TSnew represents the target intensity value after adjustment, and f represents the frequency.

7. The sound field control calculation method based on the gradient phase change of the bright spot model according to claim 6, characterized in that, In step S62, the parameters of the genetic algorithm are set, including: initial population size 500, crossover rate 0.5, elite rate 0.3, maximum number of generations 400, and other parameters are all default values.

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