A method for manufacturing a bionic anisotropic acoustic superstructure

Abstract

The present invention provides a method for manufacturing a biomimetic anisotropic acoustic superstructure, relating to the field of additive manufacturing technology. The method comprises: obtaining a fly's eye sandwich structure by simulating the structural characteristics of the fly's eye; determining a parameter combination of the fly's eye sandwich structure to construct an initial model; determining noise analysis environment parameters and optimization targets, performing noise simulation on the initial model, and obtaining a final three-dimensional model; determining additive and subtractive regions based on design requirements; determining a laser deposition strategy; performing additive manufacturing in the additive region using the laser deposition strategy to obtain a macroscopic array structure; and performing subtractive manufacturing in the subtractive region using different laser processing methods to form a microscopic array structure. The present invention achieves material-structure-performance integrated manufacturing of a biomimetic anisotropic acoustic superstructure, fully accounting for the spatially anisotropic material distribution and achieving excellent acoustic wave control characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a method for manufacturing a bionic anisotropic acoustic superstructure. Background Art

[0002] Faced with the dramatic transformation of the environmentally friendly shipping industry, the issue of acoustic pollution has become increasingly concerning, and calls for "acoustic neutralization" are growing louder to prevent and control shipping. After millions of years of evolution, organisms in nature have developed external and internal structures that have excellent performance in response to external environments. This is the result of natural selection, where the fittest survive.

[0003] So far, a variety of superstructures have been designed based on the concept of bionics to achieve noise suppression. Bionic structures often have complex geometric shapes and anisotropic material distribution. Therefore, traditional machining technology is difficult to meet the manufacturing needs of bionic structures. Additive manufacturing technology, which integrates multiple disciplines such as physics, electromechanics, optics, and materials, is a representative technology of advanced manufacturing. It is known as one of the landmark technologies of the third industrial revolution and is expected to solve the problem of fast and high-precision manufacturing of complex bionic structures. Complex bionic structures usually have their own characteristics at different scales. Traditional laser additive manufacturing methods are difficult to meet the needs of rapid manufacturing. There is an urgent need for a cross-scale composite manufacturing method to provide new ideas for the material distribution and geometric shape of bionic anisotropic superstructures.

[0004] Chinese patent application number 201410336236.2 discloses a method for designing biomimetic acoustic metamaterials for the cochlea and cochlear hair cells. This method, based on analogy to the structure and function of the cochlea, includes the design of intelligent broadband biomimetic acoustic devices and broadband mechanical wave energy recovery devices that mimic the function and structure of the entire cochlea, as well as the design of integrated ciliary composite biomimetic acoustic metamaterials that mimic the function and structure of hair cells. However, this existing technology can only meet simple requirements but cannot meet the needs of noise control, and the accuracy of the metastructure cannot be guaranteed. Summary of the Invention

[0005] In view of this, the present invention provides a method for manufacturing a bionic anisotropic acoustic superstructure. Based on the bionic fly's compound eye, a multi-scale characteristic composite acoustic superstructure is designed, and based on selective plasma micro-impact-ultrafast laser etching composite laser additive and subtractive material manufacturing, the material-structure-performance integrated manufacturing of the bionic anisotropic acoustic superstructure is realized, which can fully consider the spatial anisotropic material distribution and achieve excellent sound wave control characteristics.

[0006] The technical purpose of the present invention is achieved in this way:

[0007] The present invention provides a method for manufacturing a bionic anisotropic acoustic superstructure, comprising the following steps:

[0008] S1 biomimetic fly compound eye structural characteristics, and the structural characteristics of the fly compound eye are analyzed to obtain the fly compound eye sandwich structure, which is composed of inner layer array units, outer layer array units and middle layer array units. Among them, the inner layer array units and outer layer array units are macro arrays, and the middle layer array units are micro arrays;

[0009] S2 determines the parameter combination of the fly's eye sandwich structure, iteratively calculates the parameter combination based on the conjugate gradient method, obtains the optimal parameter combination, and constructs the initial model based on the optimal parameter combination;

[0010] S3 determines the noise analysis environment parameters and optimization targets, performs noise simulation on the initial model, and further optimizes the parameter combination of the initial model according to the optimization targets to obtain the final three-dimensional model;

[0011] S4 determines the material addition area and material reduction area according to the design requirements;

[0012] S5 performs slicing and layering processing on the three-dimensional model to obtain layered contour data, and determines the laser deposition strategy according to the layered contour data;

[0013] S6 uses a laser deposition strategy to perform additive manufacturing in the additive area to establish a macro array structure;

[0014] S7 divides the subtractive area into a first sub-area and a second sub-area according to the size range, performs subtractive manufacturing on the first sub-area using a first laser processing method, and performs subtractive manufacturing on the second sub-area using a second laser processing method to form a micro array structure.

[0015] On the basis of the above solution, preferably, in step S2, the parameter combination includes cell type, cell number, geometric parameters and materials used in the fly's eye sandwich structure.

[0016] Based on the above solution, preferably, step S3 includes:

[0017] S31 determines noise analysis environment parameters, including temperature cycle load and mechanical vibration load;

[0018] S32 determines that the optimization target is a sound pressure level less than 10dB;

[0019] S33 applies temperature cycle load and mechanical vibration load, simulates the initial model, and calculates the response of the acoustic field. After the simulation is completed, the simulation results are obtained, including sound pressure level and acoustic field distribution;

[0020] S34 evaluates the performance of the initial model in a noisy environment based on simulation results:

[0021] If the sound pressure level is not less than 10 dB, the parameters in the parameter combination are adjusted to obtain a new initial model and the process goes to step S33 to perform the simulation again.

[0022] If the sound pressure level is less than 10 dB, the current parameter combination is used as the final parameter combination, and the final three-dimensional model is obtained according to the final parameter combination.

[0023] Based on the above solution, preferably, step S33 includes:

[0024] Apply temperature cycle loads and mechanical vibration loads to simulate the acoustic field response under actual working conditions;

[0025] Set the acoustic-solid coupling boundary, including the boundary conditions of the acoustic medium domain and the solid structure domain;

[0026] According to the Helmholtz equation, the acoustic medium domain is discretized by finite element method, and a numerical equation for solving the sound field is established. By solving the numerical equation, the distribution of the sound field is obtained;

[0027] The sound pressure at any point in the solid structure domain is calculated according to the sound pressure calculation formula, and the sound pressure level is calculated based on the sound pressure.

[0028] Based on the above solution, preferably, the Helmholtz equation for plane acoustic waves in an ideal medium is:

[0029]

[0030] Where p is the sound pressure; is the Laplace operator, which represents the sum of the second-order partial derivatives; k is the wave number, and the relationship between it and the sound wave frequency f and the sound speed c is k = 2πf / c;

[0031] The sound pressure calculation formula is:

[0032]

[0033] Where, ∫ Γ Refers to the integration of the entire solid domain; s is the displacement response of the acoustic-solid coupling boundary; i is the imaginary unit; ω is the excitation frequency; g is the pressure response of the acoustic-solid coupling boundary; h is the pressure response of the solid domain; Y is the acoustic-solid coupling boundary matrix of the solid domain; H is the pressure response matrix of the solid domain; G is the pressure response matrix of the acoustic-solid coupling boundary; A is the transfer matrix of the acoustic-solid coupling boundary; f(ω) is the excitation function at the excitation frequency ω; n is the unit external normal vector;

[0034] The formula for calculating the sound pressure level is:

[0035] SPL=20*log(10(p / Pref))

[0036] Where SPL is the sound pressure level; p is the sound pressure; and Pref is the reference sound pressure.

[0037] Based on the above solution, preferably, in step S6, the laser deposition strategy specifically includes:

[0038] The additive manufacturing process is carried out in an argon environment;

[0039] The laser power is 1200W, the scanning speed is 1m / s, the overlap rate is 50%, and the powder feeding rate is 3g / min;

[0040] Using ultrasonic coaxial powder feeding, during the additive manufacturing process, the powder mixing ratio transitions from 8:2 to 2:8 to achieve material gradient distribution;

[0041] The powder mixing ratio is the ratio of the material powder of the macro array to the material powder of the micro array.

[0042] Based on the above solution, preferably, in step S7, the first laser processing method includes:

[0043] A femtosecond pulse laser with a wavelength of 1030 nm, a repetition rate of 19.12 MHz, a pulse width of 800 fs, a scanning speed of 1 m / s, and a spot overlap rate of 75% was used.

[0044] The second laser processing method includes:

[0045] An ultrashort pulse femtosecond laser is used to induce plasma microshock. The pulse width of the ultrashort pulse femtosecond laser is 220fs, the single pulse energy is 100μJ, and the polarization state is horizontal polarization.

[0046] Based on the above solution, preferably, the macro array is a submillimeter structure, and the micro array is a micron structure.

[0047] Based on the above solution, preferably, in the final three-dimensional model, the macro array adopts IN 718 material and the micro array adopts AlSi10Mg material.

[0048] On the basis of the above scheme, preferably, the temperature cycle load is to set the temperature to 10℃-40℃ cycle, and the mechanical vibration load is to apply random vibration harmonic excitation, wherein the excitation frequency is 100Hz and the amplitude acceleration is 300mm / s 2 , amplitude speed is 9mm / s.

[0049] The method of the present invention has the following beneficial effects compared to the prior art:

[0050] (1) The present invention analyzes the structural characteristics of the fly's eye to obtain the cellular characteristics of the fly's eye sandwich structure, thereby achieving efficient biomimetic structural design, so that the manufactured acoustic superstructure has excellent performance. Furthermore, through additive and subtractive manufacturing, the acoustic superstructure is precisely manufactured to ensure the accuracy of its geometric shape and size.

[0051] (2) The present invention uses noise simulation technology to perform noise analysis on the initial model, so that the acoustic superstructure has better performance in a specific noise environment and improves its noise control capability;

[0052] (3) The present invention proposes a selective plasma micro-impact-ultrafast laser etching composite additive and subtractive manufacturing method for the designed bionic superstructure, which can be customized according to the material and structure, breaking through the shackles of traditional additive manufacturing with low precision and inability to manufacture high-precision structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0055] Figure 2 Schematic diagram of the fly eye structure in an embodiment of the present invention;

[0056] Figure 3 A schematic diagram of a fly's eye sandwich structure according to an embodiment of the present invention;

[0057] Figure 4 Schematic diagram of the manufacturing process of an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only 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 making creative efforts are within the scope of protection of the present invention.

[0059] like Figure 1 As shown, the present invention provides a method for manufacturing a biomimetic anisotropic acoustic superstructure, comprising the following steps:

[0060] S1 bionic fly compound eye structural characteristics, and the structural characteristics of the fly compound eye are analyzed to obtain the cellular characteristics of the fly compound eye sandwich structure. The fly compound eye sandwich structure consists of inner layer array units, outer layer array units and middle layer array units. Among them, the inner layer array units and outer layer array units are macro arrays, and the middle layer array units are micro arrays.

[0061] S2 determines the parameter combination of the fly's eye sandwich structure, iteratively calculates the parameter combination based on the conjugate gradient method, obtains the optimal parameter combination, and constructs the initial model based on the optimal parameter combination;

[0062] S3 determines the noise analysis environment parameters and optimization targets, performs noise simulation on the initial model, and further optimizes the parameter combination of the initial model according to the optimization targets to obtain the final three-dimensional model;

[0063] S4 determines the material addition area and material reduction area according to the design requirements;

[0064] S5 performs slicing and layering processing on the three-dimensional model to obtain layered contour data, and determines the laser deposition strategy according to the layered contour data;

[0065] S6 uses a laser deposition strategy to perform additive manufacturing in the additive area to build a macro array structure;

[0066] S7 divides the subtractive area into a first sub-area and a second sub-area according to the size range, performs subtractive manufacturing on the first sub-area using a first laser processing method, and performs subtractive manufacturing on the second sub-area using a second laser processing method to form a micro array structure.

[0067] The fly compound eye structure of the present invention is as follows Figure 2 As shown, it is a sandwich structure, which is formed by expanding the hexagonal cells arranged in an array. By analyzing the structural characteristics of the fly's eye, the cellular characteristics of its sandwich structure can be obtained. According to the cellular characteristics, the acoustic superstructure of the present invention is designed. It is a fly's eye sandwich structure, which consists of an inner array unit, an outer array unit and an intermediate array unit. The intermediate array unit is embedded between the inner array unit and the outer array unit. The specific structure is as shown in FIG. Figure 3 As shown, the inner array unit and the outer array unit are macro arrays, which are sub-millimeter structures. Figure 3 The unit side length of the hexagonal macro array is 1 mm; the middle layer array unit is a microstructure, that is, Figure 3 The cell size of the mesoscopic, microscopic array shown in does not exceed the cell size of the macroscopic array.

[0068] In one embodiment of the present invention, step S2 includes:

[0069] Determine the parameter combination of the fly's eye sandwich structure, the parameter combination including cell type, cell number, geometric parameters and the material used in the fly's eye sandwich structure.

[0070] Cell type: The fly's eye sandwich structure can be composed of different types of cells, such as squares, hexagons, etc. The cell type is determined to determine the shape of each cell. In this embodiment, a hexagon is selected.

[0071] Number of cells: Determine the number of cells in the fly eye sandwich structure. The choice of the number of cells may be limited by practical application and design requirements.

[0072] Geometric parameters: including the size, spacing, and arrangement of cells. These geometric parameters determine the shape and layout of the fly's eye sandwich structure.

[0073] Materials: Select the materials that constitute the sandwich structure of the fly's eye, including the materials used in the macro array and the materials used in the micro array.

[0074] After determining the parameter combination, an iterative calculation based on the conjugate gradient method can be used to obtain the optimal parameter combination. This iterative calculation method is an optimization algorithm that continuously adjusts the parameter combination to minimize or maximize the objective function. Here, through iterative calculation, the optimal parameter combination is found to achieve the optimal performance of the fly's eye sandwich structure. Based on this optimal parameter combination, an initial model is constructed, representing the initial design of the fly's eye sandwich structure. This initial model will serve as the basis for further analysis, optimization, and evaluation in subsequent steps.

[0075] Specifically, in one embodiment of the present invention, step S3 includes:

[0076] S31 determines noise analysis environment parameters, including temperature cycle load and mechanical vibration load.

[0077] Temperature cycling load refers to the temperature change to which the model is subjected within a certain period of time. Mechanical vibration load refers to the mechanical vibration force to which the model is subjected.

[0078] In this embodiment, the temperature cycle load is set to cycle at a temperature of 10°C-40°C, and the mechanical vibration load is applied with random vibration harmonic excitation, wherein the excitation frequency is 100 Hz and the amplitude acceleration is 300 mm / s. 2 , amplitude speed is 9mm / s.

[0079] S32 determines that the optimization target is a sound pressure level less than 10 dB.

[0080] Sound pressure level is a measure of sound intensity; a level less than 10dB indicates low noise levels. By setting the optimization objective to a sound pressure level less than 10dB, we ensure that the model performs well in noisy environments.

[0081] S33 applies temperature cycle load and mechanical vibration load, simulates the initial model, and calculates the response of the sound field. After the simulation, the simulation results are obtained, including sound pressure level and sound field distribution.

[0082] Specifically, step S33 includes:

[0083] Temperature cycle loads and mechanical vibration loads are applied to simulate the acoustic field response under actual working conditions.

[0084] Set up acoustic-solid coupling boundaries, including boundary conditions between the acoustic medium domain and the solid structure domain. In acoustic simulations, you need to define boundary conditions between the acoustic medium domain and the solid structure domain to implement acoustic-solid coupling analysis. These boundary conditions can include acoustic pressure, velocity, displacement, and more.

[0085] According to the Helmholtz equation, the acoustic medium domain is discretized by finite element method, and a numerical equation for solving the sound field is established. By solving the numerical equation, the distribution of the sound field is obtained.

[0086] Specifically, discrete points on the boundary, called boundary elements or boundary nodes, are selected. These boundary elements represent the boundary conditions of the acoustic field. Finite element discretization is performed on the interior of the acoustic medium domain. Based on the Helmholtz equation, the pressure of the acoustic field can be discretized within this interior.

[0087] The Helmholtz equation for plane acoustic waves in an ideal medium is:

[0088]

[0089] Where p is the sound pressure; is the Laplace operator, representing the sum of second-order partial derivatives; k is the wave number, and its relationship with the sound wave frequency f and the sound speed c is k = 2πf / c. This equation is the numerical equation of the sound field.

[0090] The numerical equations of the acoustic field can be solved by dividing the acoustic medium domain into several small units. The pressure p(x, y, z) on each small unit can be expressed by a linear combination of the finite element basis functions N(x, y, z):

[0091] p(x,y,z)=∑N i (x,y,z)p i

[0092] Among them, N i (x, y, z) is the finite element basis function, pi is the pressure value on the corresponding node.

[0093] Substituting the above expression into the Helmholtz equation, we can obtain:

[0094]

[0095] For each small unit, the weighted residual method of the finite element method can be used to multiply the above equation by the weight function W i (x,y,z), and integrate over the entire acoustic medium domain to obtain the discretized numerical equation:

[0096]

[0097] Where dV represents the volume of the small unit.

[0098] By summing up each small unit, the numerical equation for the entire acoustic medium domain can be obtained:

[0099]

[0100] Finally, the numerical equation of the sound field can be obtained based on the boundary conditions and the response functions of the internal nodes.

[0101] After the numerical equation is obtained, it can be solved by Gaussian elimination method, Jacobi iteration method, Gauss-Seidel iteration method or successive super relaxation iteration method to obtain the distribution of the sound field.

[0102] The sound pressure at any point in the solid structure domain is calculated according to the sound pressure calculation formula, and the sound pressure level is calculated based on the sound pressure.

[0103] The sound pressure calculation formula is:

[0104]

[0105] Where, ∫ Γ Refers to the integration of the entire solid domain; s is the displacement response of the acoustic-solid coupling boundary; i is the imaginary unit; ω is the excitation frequency; g is the pressure response of the acoustic-solid coupling boundary; h is the pressure response of the solid domain; Y is the acoustic-solid coupling boundary matrix of the solid domain; H is the pressure response matrix of the solid domain; G is the pressure response matrix of the acoustic-solid coupling boundary; A is the transfer matrix of the acoustic-solid coupling boundary; f(ω) is the excitation function at the excitation frequency ω; n is the unit external normal vector;

[0106] The formula for calculating the sound pressure level is:

[0107] SPL=20*log(10(p / Pref))

[0108] Where SPL is the sound pressure level; p is the sound pressure; and Pref is the reference sound pressure.

[0109] S34 evaluates the performance of the initial model in a noisy environment based on simulation results:

[0110] If the sound pressure level is not less than 10 dB, the parameters in the parameter combination are adjusted to obtain a new initial model and the process goes to step S33 to perform the simulation again.

[0111] If the sound pressure level is less than 10 dB, the current parameter combination is used as the final parameter combination, and the final three-dimensional model is obtained according to the final parameter combination.

[0112] Through the above iterative optimization process, a parameter combination that meets the sound pressure level can be finally obtained, and the final three-dimensional model can be obtained based on this parameter combination.

[0113] Specifically, in this embodiment, after the initial model is optimized by the conjugate gradient method and the noise simulation, in the final three-dimensional model, the material of the macro array is IN 718 material, which is a high-temperature alloy material. It is a nickel-based alloy, also known as nickel-chromium alloy 718. It has strong impact resistance and can absorb sound wave impact well, but has poor toughness; the micro array uses AlSi10Mg material, which is an aluminum-based alloy material. It is an alloy composed of elements such as aluminum (Al), silicon (Si) and magnesium (Mg). It has the advantages of light weight and high toughness, but low strength; the use of these two materials, while maintaining the unique properties of nickel and aluminum alloys, has a "complementary effect", which can better exert the sound wave control function.

[0114] In one embodiment of the present invention, step S4 includes:

[0115] After obtaining a 3D model, the strategy for additive and subtractive manufacturing must be determined. Specifically, according to the design requirements, additive and subtractive regions are defined on the 3D model. Additive regions are where the object is built through laser deposition, while subtractive regions are where microstructures are formed through etching or material removal. Additive regions are used for additive manufacturing of macro-array structures, while subtractive regions are used for subtractive manufacturing of micro-array structures.

[0116] In one embodiment of the present invention, step S5 includes:

[0117] Slicing and layering: In this step, the 3D model is sliced ​​and layered along planes perpendicular to the build direction. This divides the 3D model into a series of 2D slices, each representing a horizontal layer of the built object.

[0118] Hierarchical Contour Data Acquisition: For each slice, its contour data is acquired. This can be achieved by extracting boundary points or boundary curves on the slice plane. By acquiring contour data for each slice, the shape and boundary of each layer can be understood.

[0119] Laser deposition strategy determination: Based on the layered profile data, the laser deposition strategy can be determined. The laser deposition strategy specifically includes:

[0120] The additive manufacturing process is carried out in an argon environment.

[0121] The laser power is 1200W, the scanning speed is 1m / s, the overlap rate is 50%, and the powder feeding rate is 3g / min.

[0122] Using ultrasonic coaxial powder feeding, during the additive manufacturing process, the powder mixing ratio transitions from 8:2 to 2:8 to achieve material gradient distribution;

[0123] The powder mixing ratio is the ratio of the material powder of the macro array to the material powder of the micro array.

[0124] Specifically, during additive manufacturing, the use of an argon environment can provide a degree of protection. Argon is an inert gas with excellent chemical stability and thermal conductivity. During laser deposition, argon reduces oxidation and contamination of the material, improving its quality and purity. Furthermore, argon provides a cooling effect, helping to control the material's temperature and prevent overheating and deformation.

[0125] Laser power, scan speed, overlap ratio, and powder feed rate: These parameters are critical in the laser deposition process and have a significant impact on the quality and performance of the final product.

[0126] Laser power: The selection of laser power should take into account the material's melting and sintering temperatures, as well as the desired deposition rate. Higher laser power can increase deposition speed, but may also cause overheating and material deformation. A laser power of 1200W can maintain deposition speed while controlling material temperature.

[0127] Scanning speed: Scanning speed determines the dwell time of the laser on the material surface. Higher scanning speeds can improve production efficiency, but may also lead to reduced deposition quality. A scanning speed of 1m / s can ensure production efficiency while controlling deposition quality.

[0128] Overlap rate: The overlap rate refers to the degree of overlap between adjacent scan paths. A higher overlap rate can improve deposition density and bond strength, but it also increases material consumption and manufacturing time. A 50% overlap rate can ensure structural strength while controlling material consumption and manufacturing time.

[0129] Powder feed rate: The powder feed rate refers to the rate at which the material powder is added. A higher feed rate can increase the deposition rate, but it can also lead to excessive powder accumulation and uneven deposition. A feed rate of 3g / min can control powder accumulation and distribution while maintaining a high deposition rate.

[0130] Ultrasonic coaxial powder feeding is a powder injection technology that uses ultrasonic waves to deliver powder into the laser melting area. This method can achieve uniform powder injection and distribution, improving deposition quality and uniformity.

[0131] The powder mix ratio is the ratio of material powders in the macro and micro arrays. By adjusting the powder mix ratio, a gradient distribution of materials can be achieved. For example, transitioning from an 8:2 powder mix ratio to a 2:8 powder mix ratio can achieve a gradual change in material properties during the additive manufacturing process. This gradient distribution can provide improved mechanical, chemical, and acoustic properties.

[0132] In one embodiment of the present invention, step S6 includes:

[0133] 1. Prepare the material powder and equipment required for additive manufacturing. Ensure the equipment is operating in an argon environment and set the laser power to 1200W.

[0134] 2. Depending on the desired macro array structure, set the scanning speed to 1 m / s and the overlap rate to 50%. These parameters will affect the time the laser stays on the material surface and the degree of overlap between adjacent scanning paths.

[0135] 3. Set the powder mixing ratio according to the required material gradient distribution.

[0136] 4. Use ultrasonic coaxial powder feeding to spray powder into the laser melting area.

[0137] 5. Start the laser deposition process. The laser melts the material powder in an argon atmosphere. According to the set scanning parameters, the laser scans the material surface at a speed of 1m / s, while controlling the laser power and overlap rate.

[0138] 6. As additive manufacturing progresses, the ratio of material powder gradually transitions from 8:2 to 2:8 according to the set powder mixing ratio.

[0139] 7. During the additive manufacturing process, the powder feeding rate was controlled at 3 g / min to control the accumulation and distribution of powder.

[0140] 8. Continue laser deposition until the macro array structure is completed, depending on the desired manufacturing size and shape. For example, if the shape is hexagonal, the manufacturing size is 1 mm per side.

[0141] In one embodiment of the present invention, in step S7, the relevant contents are described in detail as follows:

[0142] Divide the subtractive area: Divide the subtractive area into the first sub-area and the second sub-area according to the size range.

[0143] First Laser Processing Method: Subtractive manufacturing was performed on the first sub-region using the first laser processing method. This method used a femtosecond pulsed laser with a wavelength of 1030 nm. The repetition rate of the femtosecond pulsed laser was 19.12 MHz, and the pulse width was 800 fs. The laser scanning speed was set to 1 m / s, and the spot overlap was 75%.

[0144] Second laser processing method: Subtractive manufacturing of the second sub-region is performed using a second laser processing method. This method uses ultrashort pulse femtosecond laser-induced plasma micro-shocks. The ultrashort pulse femtosecond laser has a pulse width of 220 fs, a single pulse energy of 100 μJ, and a horizontal polarization state.

[0145] Step S7 is described with a specific embodiment:

[0146] 1. Design the subtractive area: Determine the shape, size, and location of the subtractive area based on actual needs and design requirements. Specifically, in this embodiment, the shape is a simulated hole with a size of 5 μm and a location within the range of the macro array unit cell.

[0147] 2. Divide the subtractive area: Divide the subtractive area into a first sub-area and a second sub-area based on the size range. Specifically, the first sub-area is a larger pattern area with a size ranging from 10μm to 100μm; the second sub-area is a smaller area with a size range below 10μm.

[0148] 3. Laser processing of the first sub-area: Subtractive manufacturing is performed on the first sub-area using the first laser processing method. The laser output beam is focused onto the first sub-area through a lens system. The laser scanning speed and spot overlap ratio are controlled to enable interaction between the laser and the material, achieving subtractive manufacturing. The first laser processing method uses a femtosecond pulsed laser with a wavelength of 1030nm, a repetition rate of 19.12MHz, and a pulse width of 800fs. The scanning speed is set to 1m / s, and the spot overlap ratio is 75%.

[0149] 4. Laser processing of the second sub-area: Subtractive manufacturing of the second sub-area is performed using the second laser processing method. An ultrashort pulse femtosecond laser is focused onto the second sub-area through a lens system. The laser parameters are controlled to allow interaction between the laser and the material, achieving subtractive manufacturing. The second laser processing method uses ultrashort pulse femtosecond laser-induced plasma microshocks. The ultrashort pulse femtosecond laser has a pulse width of 220 fs, a single pulse energy of 100 μJ, and a horizontal polarization state.

[0150] 5. Forming a Microscopic Array Structure: Through laser processing of the first and second sub-regions, a subtractive manufacturing process forms a microscopic array structure. Different laser processing methods for the first and second sub-regions can achieve different microstructural morphologies.

[0151] 6. Post-processing: Based on actual needs and design requirements, subsequent cleaning, surface treatment, and other process steps may be performed to achieve the final manufacturing goal. For example, the material after subtractive manufacturing must be cleaned. Dust, oil, and other contaminants on the surface can be removed using solvents, ultrasonic cleaners, and other tools. The treated material is inspected to ensure that the surface treatment meets the requirements. If surface defects or non-compliance are found, repairs can be performed. Repair methods may include polishing and coating. The treated material is then subjected to a final inspection to ensure that the surface quality and treatment effect meet the manufacturing requirements.

[0152] It should be noted that the present embodiment achieves the following effects by adopting different laser processing methods:

[0153] 1. Better meet the manufacturing needs of different regions. The high overlap rate and fast scanning speed of the first laser processing method can improve manufacturing efficiency, while the ultra-short pulse and micro-impact of the second laser processing method can achieve higher manufacturing precision.

[0154] 2. Introducing diversity in the structure of the microscopic array. For example, the first sub-region has a flatter and more uniform surface, while the second sub-region has more subtle and complex structural features.

[0155] 3. Adapt to different material properties and manufacturing requirements. For example, the first laser processing method is suitable for melting and solidifying materials, while the second laser processing method is suitable for micro-deformation and surface modification of materials.

[0156] See also Figure 4 , Figure 4It is a schematic diagram of the overall manufacturing process of the present invention. The present invention first determines the bionic fly eye sandwich structure to be manufactured by the present invention by analyzing the fly eye structure, and then determines the parameter combination of the structure, including the required various structural parameters, to establish an initial model. Then, the external loads such as temperature and mechanical vibration are determined to perform noise simulation on the initial model. The sound pressure level is obtained according to the thermosetting acoustic coupling calculation to determine whether the sound pressure level meets the requirement. If not, the model establishment stage is returned to the update parameter combination and the noise simulation is performed again until the sound pressure level meets the requirement. Then, the additive and subtractive areas are determined, the deposition laser parameters are set in the additive area, and the infrared array is manufactured by directional deposition. After that, the area is subtracted and divided into two sub-areas according to the size range. Femtosecond laser etching and plasma impact are used for subtractive manufacturing respectively to form a microstructure, i.e., a micro array. After the manufacturing is completed, the fly eye sandwich structure is obtained.

[0157] The present invention breaks through the problem that the single scale of existing superstructures is difficult to meet specific functional requirements. It proposes a method of designing a multi-scale characteristic composite acoustic superstructure based on the bionic fly compound eye, which can further broaden the design ideas of acoustic superstructures. In view of the problem that existing technologies are difficult to manufacture cross-scale anisotropic composite structures, selective plasma micro-impact-ultrafast laser etching composite laser additive and subtractive manufacturing is proposed, which provides a new way for the integrated forming of cross-scale structures.

[0158] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for manufacturing a biomimetic anisotropic acoustic superstructure, characterized in that: The following steps are involved: S1 The structural characteristics of the bionic fly compound eye are analyzed to obtain the fly compound eye sandwich structure. The fly compound eye sandwich structure consists of inner array units, outer array units, and middle array units. Among them, the inner array units and outer array units are macro arrays, and the middle array units are micro arrays. S2 determines the parameter combination of the fly's eye sandwich structure, iteratively calculates the parameter combination based on the conjugate gradient method, obtains the optimal parameter combination, and constructs the initial model based on the optimal parameter combination; S3 determines the noise analysis environment parameters and optimization targets, performs noise simulation on the initial model, and further optimizes the parameter combination of the initial model according to the optimization targets to obtain the final 3D model; S4 Determine the material addition area and material reduction area according to design requirements; S5 slices and layers the three-dimensional model to obtain layered contour data, and determines the laser deposition strategy based on the layered contour data; S6 uses a laser deposition strategy to perform additive manufacturing in the additive area to build a macro array structure; S7 divides the subtractive region into a first subregion and a second subregion according to the size range, performs subtractive manufacturing on the first subregion using a first laser processing method, and performs subtractive manufacturing on the second subregion using a second laser processing method to form a microscopic array structure; Step S3 includes the following steps: S31 Determine noise analysis environment parameters, including temperature cycle load and mechanical vibration load; S32 determines that the optimization target is a sound pressure level less than 10dB; S33 applies temperature cycle loads and mechanical vibration loads, simulates the initial model, and calculates the response of the acoustic field. After the simulation, the simulation results are obtained, including the sound pressure level and acoustic field distribution; S34 evaluates the performance of the initial model in a noisy environment based on simulation results.

2. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 1, wherein: In step S2, the parameter combination includes the cell type, the number of cells, the geometric parameters and the material used in the fly's eye sandwich structure.

3. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 1, wherein: In step S34, the performance of the initial model in a noisy environment is evaluated based on the simulation results, specifically including: If the sound pressure level is not less than 10 dB, the parameters in the parameter combination are adjusted to obtain a new initial model and the process goes to step S33 to perform the simulation again. If the sound pressure level is less than 10 dB, the current parameter combination is used as the final parameter combination, and the final three-dimensional model is obtained according to the final parameter combination.

4. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 3, wherein: Step S33 includes the following steps: Apply temperature cycle loads and mechanical vibration loads to simulate the acoustic field response under actual working conditions; Set the acoustic-solid coupling boundary, including the boundary conditions of the acoustic medium domain and the solid structure domain; According to the Helmholtz equation, the acoustic medium domain is discretized by finite element method, and a numerical equation for solving the sound field is established. By solving the numerical equation, the distribution of the sound field is obtained; The sound pressure at any point in the solid structure domain is calculated according to the sound pressure calculation formula, and the sound pressure level is calculated based on the sound pressure.

5. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 4, wherein: The Helmholtz equation for plane acoustic waves in an ideal medium is: ； Where, is the sound pressure; is the Laplace operator, which represents the sum of second-order partial derivatives; is the wave number, which is the same as the sound wave frequency f Harmony c The relationship between ; The sound pressure calculation formula is: ； Where, refers to the integration over the entire solid domain; is the displacement response of the acoustic-solid coupling boundary; is an imaginary unit; is the excitation frequency; is the pressure response of the acoustic-solid coupling boundary; is the pressure response of the solid domain; is the acoustic-solid coupling boundary matrix of the solid domain; is the pressure response matrix of the solid domain; is the pressure response matrix of the acoustic-solid coupling boundary; is the transfer matrix of the acoustic-solid coupling boundary; is the excitation frequency The activation function at ; is the unit external normal vector; The formula for calculating the sound pressure level is: ； Where, is the sound pressure level; is the sound pressure; is the reference sound pressure.

6. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 1, wherein: In step S6, the laser deposition strategy specifically includes: The additive manufacturing process is carried out in an argon environment; The laser power is 1200W, the scanning speed is 1m / s, the overlap rate is 50%, and the powder feeding rate is 3g / min; Using ultrasonic coaxial powder feeding, during the additive manufacturing process, the powder mixing ratio transitions from 8:2 to 2:8 to achieve material gradient distribution; The powder mixing ratio is the ratio of the material powder of the macro array to the material powder of the micro array.

7. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 1, wherein: In step S7, the first laser processing method includes: A femtosecond pulse laser with a wavelength of 1030 nm, a repetition rate of 19.12 MHz, a pulse width of 800 fs, a scanning speed of 1 m / s, and a spot overlap rate of 75% was used; The second laser processing method includes: An ultrashort pulse femtosecond laser is used to induce plasma microshock. The pulse width of the ultrashort pulse femtosecond laser is 220fs, the single pulse energy is 100μJ, and the polarization state is horizontal polarization.

8. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 1, wherein: The macro array is a submillimeter structure, and the micro array is a micron structure.

9. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 1, wherein: In the final 3D model, the macro array is made of IN 718 material and the micro array is made of AlSi10Mg material.

10. The method for manufacturing a biomimetic anisotropic acoustic superstructure according to claim 3, wherein: The temperature cycle load is a cycle with a set temperature of 10℃-40℃, and the mechanical vibration load is a random vibration harmonic excitation with an excitation frequency of 100Hz and an amplitude acceleration of 300mm / s. 2 , amplitude speed is 9mm / s.

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