Method and device for predicting the profile of a laser drilled hole in a composite material

Abstract

The present application relates to the technical field of laser processing, and provides a kind of prediction method and device for laser drilling hole pattern of composite material, the method comprises: constructing the geometric model of to-be-simulated composite material;Determine the boundary condition of geometric model, and determine the three-dimensional solid heat transfer and two-phase flow level set model corresponding to geometric model;According to rectangular wave function and the thickness of to-be-simulated composite material periodic arrangement, determine the heat transfer coefficient of to-be-simulated composite material in geometric model;The grid division is carried out to the geometric model and obtains multiple grid regions, and the laser drilling hole pattern is predicted according to the set parameters of each grid region.The present application uses the method of two-phase flow-level set to couple fluid heat transfer to carry out fluid dynamics simulation to reproduce laser selective melting process, can consider the case that the thermal conductivity of each layer of composite material is different, predict the shape generation process of small hole of composite material under laser irradiation, melt flow and the accumulation after melt condensation, so as to improve the efficiency of laser drilling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser processing, in particular to a prediction method and device for laser drilling hole shape of composite material. BACKGROUND

[0002] For pulsed laser processing of materials, according to its removal process, it can be divided into thermal processing removal process represented by millisecond, microsecond laser processing and non-thermal removal process represented by femtosecond, picosecond, the former is also called long pulse processing process, and the latter is called short pulse processing process. Long pulse processing process refers to using the thermal effect generated by projecting laser beam onto the material surface to complete the processing process, and in the processing process, laser obtains high energy through focusing, so as to eliminate solid materials through melting or evaporation. However, for composite materials, because the thermal physical parameters such as thermal conductivity coefficient are different in the fiber direction and the direction perpendicular to the fiber, the laser drilling finite element numerical simulation for composite materials is relatively few and simple.

[0003] At present, there are a large number of one-dimensional models related to laser drilling. Since such models are not suitable for complex conditions such as strong boiling and melt injection, they cannot predict the melt flow and the accumulation after melt condensation, cannot track the ablation surface, and cannot view the geometric shape difference of small holes formed under different laser parameters. Therefore, the existing model cannot predict the laser drilling hole shape of composite material. SUMMARY

[0004] The present application provides a prediction method and device for laser drilling hole shape of composite material, which solves the problem of predicting the laser drilling hole shape of composite material. By using the two-phase flow-level set method to couple fluid heat for fluid dynamics simulation, the laser selective melting process is reproduced. Considering the different thermal conductivity coefficients of each layer of composite material, the shape generation process of small holes, melt flow and accumulation after melt condensation of composite material under laser irradiation can be predicted, thereby improving the efficiency of laser drilling.

[0005] The present application provides a prediction method for laser drilling hole shape of composite material, comprising:

[0006] Constructing a geometric model of a composite material to be simulated;

[0007] Determining the boundary conditions of the geometric model and determining the three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model;

[0008] According to the rectangular wave function and the thickness of the periodic arrangement of the composite material to be simulated, the heat transfer coefficient of the composite material to be simulated in the geometric model is determined;

[0009] Grid the geometry model to obtain a plurality of grid regions, and predict a laser drilling hole type according to a set parameter of each grid region.

[0010] In one embodiment, the determination of the heat transfer coefficient of the composite material to be simulated in the geometry model according to the rectangular wave function and the thickness of the periodic arrangement of the composite material to be simulated comprises:

[0011] Determination of the rectangular wave function according to the radial heat transfer coefficient, the axial heat transfer coefficient and the single-layer thickness of the composite material to be simulated;

[0012] Modulo operation on the thickness of the periodic arrangement of the composite material to be simulated and the corresponding coordinate information of the composite material to be simulated;

[0013] Determination of the heat transfer coefficient of the composite material to be simulated in the geometry model according to the modulo operation result and the rectangular wave function.

[0014] In one embodiment, the grid division of the geometry model to obtain a plurality of grid regions, and the prediction of a laser drilling hole type according to a set parameter of each grid region comprises:

[0015] Determination of the grid division parameter of the geometry model;

[0016] Grid division of the geometry model according to the grid division parameter to obtain a plurality of grid regions;

[0017] Prediction of a laser drilling hole type according to the temperature, speed, pressure and phase composition of each grid region.

[0018] In one embodiment, the determination of the boundary condition of the geometry model comprises:

[0019] Determination of the initial condition, boundary heat source condition and two-phase flow level set boundary condition of the geometry model.

[0020] In one embodiment, the determination of the three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometry model comprises:

[0021] Determination of the mass conservation equation, momentum conservation equation, energy conservation equation and level set equation of the fluid;

[0022] Determination of the three-dimensional solid heat transfer and two-phase flow level set model according to the mass conservation equation, the momentum conservation equation, the energy conservation equation and the level set equation.

[0023] In one embodiment, the determination of the mass conservation equation comprises:

[0024] The mass conservation equation is determined based on the fluid velocity, a first set function, a mass loss of the composite material to be simulated, a density of the metal vapor, and a density of the liquid metal.

[0025] In one embodiment, determining the momentum conservation equation includes:

[0026] The momentum conservation equation is determined based on the fluid velocity, a body force, a unit matrix, a gravitational acceleration of the earth, a surface tension, a recoil force, a Marangoni force, a first set function, a second set function, and a dynamic viscosity, a density, a temperature, and a liquid pressure in the finite element region.

[0027] In one embodiment, determining the energy conservation equation includes:

[0028] The energy conservation equation is determined based on the fluid velocity, a density, a specific heat capacity, a temperature, and a thermal conductivity in the finite element region, a liquid density, an absorptivity of the composite material to be simulated to laser, an evaporation latent heat, a recession velocity of the evaporation front, a heat transfer coefficient, a surface emissivity, a Boltzmann constant, a first set function, a surface heat source, and an action time distribution of the laser pulse.

[0029] In one embodiment, determining the level set equation includes:

[0030] The level set equation is determined based on a level set parameter, a fluid velocity, a mass loss of the composite material to be simulated, a density of the metal vapor, a density of the liquid metal, a volume fraction of the vapor, a volume fraction of the liquid, a first set function, and a second set function.

[0031] In one embodiment, the three-dimensional solid heat transfer and two-phase flow level set model includes:

[0032] The mass conservation equation is:

[0033]

[0034] wherein, denotes a gradient operator, denotes a fluid velocity, δ denotes a first set function, denotes a mass loss of the composite material to be simulated, ρ v denotes a density of the metal vapor, ρ L denotes a density of the liquid metal, denotes a normal vector;

[0035] The momentum conservation equation is:

[0036]

[0037] wherein, denotes a gradient operator, represents a fluid velocity, p represents a density in the finite element region, p represents a liquid pressure in the finite element region, T represents a current temperature in the finite element region, μ represents a dynamic viscosity in the finite element region, I represents a unit matrix, represents a volume force, δ represents a first set function, φ represents a second set function, represents a gravitational acceleration of the earth, represents a surface tension, represents a recoil force, represents a Marangoni force, and represents a normal vector;

[0038] Energy conservation equation:

[0039]

[0040] wherein, represents a gradient operator, represents a fluid velocity, p represents a density in the finite element region, C p represents a specific heat capacity in the finite element region, k represents a thermal conductivity in the finite element region, T0 represents an initial temperature in the finite element region, T represents a current temperature in the finite element region, α represents an absorption rate of the composite material to be simulated to laser, L v represents a latent heat of evaporation, v e represents a recession velocity of the evaporation front, p l represents a liquid density, h represents a heat transfer coefficient, ξ represents a surface emissivity, k b represents a Boltzmann constant, S represents a surface heat source, g(t) represents an action time distribution of the laser pulse, δ represents a first set function;

[0041] Level set equation:

[0042]

[0043] wherein, represents a gradient operator, represents a fluid velocity, δ represents a first set function, φ represents a second set function, represents a mass loss amount of the vaporization of the composite material to be simulated, ε and γ represent level set parameters, p v represents a density of the metal vapor, p L represents a density of the liquid metal, V f,v represents a volume fraction of the vapor, V f,L represents a volume fraction of the liquid.

[0044] The application also provides a laser drilling method, comprising:

[0045] determine a first drilling parameter of a predicted laser drilling hole type;

[0046] adjust a second drilling parameter according to the first drilling parameter, and perform laser drilling according to the adjusted second drilling parameter.

[0047] The application further provides a composite material laser drilling hole type prediction device, comprising:

[0048] a construction module configured to construct a geometric model of a composite material to be simulated;

[0049] a first determination module configured to determine boundary conditions of the geometric model, and determine a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model;

[0050] a second determination module configured to determine a heat transfer coefficient of the composite material to be simulated in the geometric model according to a rectangular wave function and a thickness of periodic arrangement of the composite material to be simulated;

[0051] a prediction module configured to divide the geometric model into a plurality of grid regions, and predict a laser drilling hole type according to a set parameter of each grid region.

[0052] The application further provides a laser drilling device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the composite material laser drilling hole type prediction method or the laser drilling method.

[0053] The application further provides a non-transitory computer readable storage medium, which stores a computer program executable on a processor to implement the composite material laser drilling hole type prediction method or the laser drilling method.

[0054] The composite material laser drilling hole type prediction method and device provided by the application can reproduce a laser selective melting process by using a two-phase flow-level set method coupled with fluid heat transfer for fluid dynamics simulation, can predict a small hole shape generation process, melt flow and melt condensation and accumulation of a composite material under laser irradiation in consideration of different heat conduction coefficients of each layer of the composite material, and thus improves the efficiency of laser drilling. BRIEF DESCRIPTION OF DRAWINGS

[0055] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0056] Figure 1 This is a flowchart illustrating the method for predicting the pore shape of laser-made composite materials provided by the present invention.

[0057] Figure 2 This is a schematic diagram of the geometric model of the composite material to be simulated provided by the present invention;

[0058] Figure 3 This is a schematic diagram of the grid region provided by the present invention;

[0059] Figure 4 This is a schematic diagram of the rectangular wave function provided by the present invention;

[0060] Figure 5 This is a schematic diagram of the simulated laser hole-making provided by the present invention;

[0061] Figure 6 This is a schematic diagram of the structure of the composite material laser hole pattern prediction device provided by the present invention;

[0062] Figure 7 This is a schematic diagram of the structure of the laser hole-making device provided by the present invention. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0064] The following is combined with Figures 1-7 The present invention describes a method and apparatus for predicting the pore shape of laser-induced holes in composite materials.

[0065] Specifically, this invention provides a method for predicting the pore shape of laser-formed holes in composite materials, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the method for predicting the hole shape of laser-made composite materials provided by the present invention.

[0066] The method for predicting the pore shape of laser-induced holes in composite materials provided in this invention includes:

[0067] Step 100, constructing a geometric model of a composite material to be simulated;

[0068] It should be noted that the application simulates the whole process of material melting and sublimation by the two-phase flow-level set method in COMSOL software, and based on this, simulates the generation process of a small hole in the laser drilling process.

[0069] Specifically, for how to construct the geometric model of the composite material to be simulated, reference can be made to Figure 2 In COMSOL, a geometric model of the composite material to be simulated, i.e., a material domain model, is established, and the size of the solid region is 1mm (width) * 0.8mm (height), and the size of the gaseous region is 1mm (width) * 0.2mm (height), and the common edge of the two regions is the two-phase flow interface.

[0070] It can be understood that the material parameters, laser parameters and environmental parameters in the simulation process also need to be determined.

[0071] The material parameters mainly include one or more of the melting latent heat and the gasification latent heat of the composite material to be simulated; can also include the solid density, the thermal conductivity, and the specific heat capacity of the composite material to be simulated, and the liquid density, the thermal conductivity, and the specific heat capacity of the composite material to be simulated; can also include the phase transition temperature, the laser absorption coefficient, the convective heat transfer coefficient to the environment, and the radiation emissivity to the environment of the composite material to be simulated.

[0072] The dynamic viscosity of the solid region of the composite material to be simulated, the dynamic viscosity of the liquid region, and the surface tension coefficient and the derivative of the surface tension with respect to the temperature.

[0073] The laser parameters mainly include one or more of the laser power, the laser focal point radius, the laser action time, and the action frequency.

[0074] The environmental parameters mainly include at least one of the environmental temperature and the environmental pressure.

[0075] Step 200, determining the boundary conditions of the geometric model, and determining the three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model;

[0076] After constructing the geometric model of the composite material to be simulated, the boundary conditions of the geometric model of the composite material to be simulated need to be determined, including initial conditions, boundary heat source conditions, and two-phase flow level set boundary conditions. At the same time, the three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model need to be determined.

[0077] Step 300, determining the heat transfer coefficient of the composite material to be simulated in the geometric model according to the rectangular wave function and the thickness of the periodic arrangement of the composite material to be simulated;

[0078] It should be noted that for composite materials, the axial thermal conductivity and radial thermal conductivity of the composite material need to be considered, as well as the different thermophysical coefficients (such as the coefficient of thermal expansion) caused by the anisotropic properties of the composite material.

[0079] Based on the rectangular wave function and the thickness of the periodically laid composite material to be simulated, the heat transfer coefficient of the composite material to be simulated in the geometric model is determined. For example, by using the form of a composite function, different thermal conductivity values ​​of the composite material are assigned according to different heights of the material in the geometric model, simulating the situation where the thermal conductivity of different composite material layers is inconsistent.

[0080] Step 400: The geometric model is divided into multiple mesh regions, and the laser hole shape is predicted according to the set parameters of each mesh region;

[0081] The geometric model is meshed to obtain multiple mesh regions, which can be referenced. Figure 3 ,Depend on Figure 3 It is known that the size of each grid region can be the same or different. Then, the laser-formed hole shape is predicted based on the set parameters of each grid region. These set parameters mainly include temperature, velocity, pressure, and phase composition. For example, the melt flow and the accumulation of melt after solidification are predicted based on the temperature, velocity, pressure, and phase composition of each node, and the ablation surface is tracked. The differences in the geometric shape of the small hole formed under different laser parameters are also observed. Based on this, the laser-formed hole shape can be predicted. For example, taking temperature as an example, a 3D viewing node is created under the result node, and the temperature change result can be obtained by inputting an expression; taking velocity as an example, a 3D viewing node is created under the result node, and the velocity change result can be obtained by inputting an expression.

[0082] This invention provides a method for predicting the hole shape of laser-drilled composite materials. By setting a periodic function in COMSOL, different layers of the finite element region are given different thermal conductivity, avoiding the inability to perform finite element deformation across layers. At the same time, the laser drilling process of composite materials is simulated by using a two-phase flow-level set method. The model can predict the melt flow and the accumulation of melt after laser irradiation of the composite material. It can also track the ablation surface and observe the differences in the geometric shape of the hole formed under different laser parameters, thereby improving the efficiency of laser drilling.

[0083] In one embodiment, the heat transfer coefficient of the composite material to be simulated in the geometric model is determined according to a rectangular wave function and a thickness of a periodic arrangement of the composite material to be simulated, specifically comprising: determining the rectangular wave function according to a radial heat transfer coefficient, an axial heat transfer coefficient of the composite material to be simulated and a single layer thickness; taking a modulus of the thickness of the periodic arrangement of the composite material to be simulated and coordinate information corresponding to the composite material to be simulated; and determining the heat transfer coefficient of the composite material to be simulated in the geometric model according to the modulus result and the rectangular wave function. For example, first, a rectangular wave is established in COMSOL, with an upper limit of 1 and a lower limit of k sr / k sa , and a pulse width of a single layer thickness t f of the composite material to be simulated, where k sr represents the radial heat transfer coefficient of the composite material to be simulated, and k sa represents the axial heat transfer coefficient of the composite material to be simulated. Generally, the axial heat transfer coefficient of the composite material fiber is relatively large, and it is assumed that k sr / k sa = 1 / 2, and t f = 0.2 mm, and the rectangular wave function can be obtained as shown in FIG. 1. Figure 4

[0084] Secondly, the mod function in COMSOL is used to take a modulus of (y, t fp ), where y represents the longitudinal coordinate of the composite material to be simulated, and t fp represents the thickness of the periodic arrangement of the composite material to be simulated, such as a (0 / 90) cyclic arrangement of the composite material with a thickness of 0.2 mm, and the thickness of the periodic arrangement is 0.4 mm, where t fp / t f represents the number of layers of the periodically arranged composite material.

[0085] Finally, the modulus result is input into the rectangular wave function and multiplied by the axial heat transfer coefficient k sa of the composite material to be simulated, and the heat transfer coefficient of the composite material to be simulated varying with the thickness of the composite material to be simulated can be obtained, and the specific expression is as follows:

[0086] k1 = k sa *rect(mod(y, t fp )) (1)

[0087] In formula (1), k1 represents the heat transfer coefficient of the composite material to be simulated, k sa represents the axial heat transfer coefficient of the composite material to be simulated, y represents the longitudinal coordinate of the composite material to be simulated, and t fp represents the thickness of the periodic arrangement of the composite material to be simulated.

[0088] ​The embodiments of the present invention determine the heat transfer coefficient of the composite material to be simulated in the geometric model based on the model taking results and the rectangular wave function, thereby improving the accuracy of determining the heat transfer coefficient and further improving the accuracy of predicting the laser-made hole shape of the composite material.

[0089] In one embodiment, a geometric model is meshed to obtain multiple mesh regions. The laser-induced aperture shape is predicted based on set parameters for each mesh region. Specifically, this includes: determining the meshing parameters of the geometric model; then, meshing the geometric model according to the meshing parameters to obtain multiple mesh regions; determining the temperature, velocity, pressure, and phase composition of each mesh region; and finally, predicting the laser-induced aperture shape based on the temperature, velocity, pressure, and phase composition of each mesh region. For example, software can automatically mesh the model using free tetrahedrons based on physical fields. The meshing structure mainly contains at least one of multiple mesh elements, multiple boundary elements, and multiple edge elements.

[0090] The method for determining the velocity of the grid region is as follows:

[0091] When a Gaussian heat source acts on an opaque material, it can be considered equivalent to a surface heat source, and its simplified expression is:

[0092]

[0093] In equation (2), S0 is the peak laser power, r0 is the laser spot radius, and x is the transverse coordinate of the finite element domain. The duration distribution of the laser pulse is as follows:

[0094]

[0095] In equation (3), t p The pulse duration, taking into account heat loss due to evaporation, convection, and surface radiation to the environment, yields the following:

[0096]

[0097] In equation (4), Let represent the gradient operator, k represent the thermal conductivity in the finite element region, T0 represent the initial temperature in the finite element region, T represent the current temperature in the finite element region, α represent the absorptivity of the composite material to be simulated for laser light, and L represent the gradient operator. v Represents the latent heat of vaporization, v e ρ represents the receding velocity of the evaporation front obtained from the vapor mass flow rate of liquid surface evaporation derived from the Hertz–Knudsen formula. l Let ξ represent the liquid density, h represent the heat transfer coefficient, ξ represent the surface emissivity, and k represent the surface emissivity. b This represents the Boltzmann constant.

[0098] Wherein, the back-off speed v can be determined by formula (4) e Based on this, the speed of each grid area can be determined.

[0099] It should be noted that the finite element region refers to the region corresponding to the geometric model of the composite material to be simulated, such as the region constructed as shown in Figure 2 .

[0100] The embodiment of the present application determines the grid division parameters of the geometric model, then performs grid division on the geometric model according to the grid division parameters to obtain a plurality of grid regions, and finally predicts the laser drilling hole type according to the temperature, speed, pressure and phase composition of each grid region. Based on this, the shape generation process of a small hole, melt flow and the accumulation after melt condensation of different materials under laser irradiation can be predicted, thereby improving the efficiency of laser drilling.

[0101] In one embodiment, the boundary conditions of the geometric model are determined, including: determining the initial conditions, boundary heat source conditions and two-phase flow level set boundary conditions of the geometric model, wherein the initial condition refers to the initial temperature of the material domain being 0 or 20℃ (room temperature); the boundary heat source condition includes heat source, heat convection and heat radiation; and the two-phase flow level set boundary condition includes surface tension, recoil force and Marangoni force (i.e. Marangoni force).

[0102] By determining the boundary conditions of the geometric model, simulation is performed based on the boundary conditions, thereby improving the accuracy of the simulation.

[0103] In one embodiment, the mass conservation equation, momentum conservation equation, energy conservation equation and level set equation of the fluid are determined, and then a three-dimensional solid heat transfer and two-phase flow level set model is determined according to the mass conservation equation, momentum conservation equation, energy conservation equation and level set equation. It should be noted that the mass conservation equation, momentum conservation equation, energy conservation equation and level set equation in the embodiment of the present application are obtained by modifying the corresponding basic equations, wherein each basic equation is as follows:

[0104] The mass conservation basic equation is:

[0105]

[0106] The momentum conservation basic equation is:

[0107]

[0108] The energy conservation basic equation is:

[0109]

[0110] In formula (5) to (7), represents the gradient operator, represents fluid velocity, μ, ρ, C p , k are the values of dynamic viscosity, density, specific heat capacity and thermal conductivity in the whole finite element region, respectively, represents volume force, I represents unit matrix, and T represents the current temperature in the finite element region, represents the gravitational acceleration of the earth (take 9.8 N / kg), and p represents the liquid pressure in the finite element region.

[0111] wherein, for the specific heat capacity of the material, the equivalent heat capacity considering the latent heat of fusion and the latent heat of vaporization of the material needs to be considered when defining:

[0112] C p,eff =C p +L m D m +L v D v (8)

[0113] In formula (8), there are are two Gaussian functions, wherein, T m and T v respectively represent the melting point and boiling point of the composite material to be simulated, L m and L v respectively represent the latent heat of fusion and the latent heat of vaporization of the composite material to be simulated, and the formula ensures that the heat capacity of the material is a continuous function, which is convenient for calling in calculation.

[0114] The level set basic equation is:

[0115]

[0116] In formula (9), ε and γ represent two level set parameters, which are related to the thickness of the level set interface and the flow rate, respectively, and φ represents the second setting function, wherein the expression of the second setting function is φ (x, y, t), the value range of φ (x, y, t) is between 0 and 1, which is used to distinguish liquid and gas phases, and is defined according to the Heaviside equation as follows:

[0117] For the material domain, y < -ε:

[0118] φ (x, y, t) = 0 (10)

[0119] For the liquid-vapor interface domain of the material, y = 0:

[0120] φ (x, y, t) = 0.5 (11)

[0121] For the vapor region, y > ε:

[0122] φ (x, y, t) = 1 (12)

[0123] It can be understood that the Heaviside equation ensures that the gasification of the molten material only occurs on the two-phase flow boundary of the two-phase flow level set, and the boundary transition zone is very smooth. The second setting function φ(x, y, t) is automatically calculated in the COMSOL finite element simulation. When the value range of the second setting function φ(x, y, t) changes between 0 and 1, the physical properties (μ, ρ, C p ,k) of the boundary will change to the following equivalent dynamic viscosity, density, specific heat capacity and thermal conductivity:

[0124] ρ=ρ l +(ρ air -ρ)φ

[0125] μ=μ l +(μ air -μ)φ (13)

[0126] k=k l +(k air -k)φ

[0127] C p =C peff +(C pair -C peff )φ (14)

[0128] This process can be understood as the physical properties (μ, ρ, C p ,k) of the material on the liquid-gas transition boundary change gradually from the physical properties (μ, ρ, C p ,k) of the liquid material to the physical properties (μ, ρ, C p ,k) of the material after gasification.

[0129] For the two-phase flow boundary, a δ function (i.e. the first setting function) is defined:

[0130]

[0131] On the two-phase flow boundary, the function has a value, and the value in other regions is 0, so multiplying the δ function in the control equation can ensure that the corresponding source term is only loaded on the solid-liquid interface. The function is also automatically calculated by the COMSOL software when calculating the two-phase flow field, which is the δ function of the fluid phase interface.

[0132] During the transition of the material from the liquid phase to the gas phase, the material will lose mass, so the mass conservation equation and the momentum conservation equation in the corresponding NS equation need to be modified, wherein the mass loss term can be expressed as:

[0133]

[0134] In formula (16), m represents the atomic mass of the metal workpiece material, k b represents the Boltzmann constant, β represents the condensation coefficient (the coefficient of vapor molecules returning to the liquid region and liquid molecules), T v represents the evaporation temperature, L v represents the latent heat of evaporation, P0 represents one standard atmosphere, and T represents the current temperature in the finite element region.

[0135] When the surface temperature exceeds the boiling point, the material will vaporize and be accompanied by mass loss, so two source terms should be added to the equation, and the equations (5) and (9) are multiplied by the delta function on the interface, respectively.

[0136] The mass conservation equation is:

[0137]

[0138] In formula (17), m represents the atomic mass of the metal workpiece material, k represents the gradient operator, represents the fluid velocity, δ represents the first set function, represents the mass loss of the composite material to be simulated, ρ v represents the density of the metal vapor, ρ L represents the density of the liquid metal, represents the normal vector.

[0139] The level set equation is:

[0140]

[0141] In formula (18), m represents the atomic mass of the metal workpiece material, k represents the gradient operator, represents the fluid velocity, δ represents the first set function, and φ represents the second set function, represents the mass loss of the composite material to be simulated, ε and γ represent the level set parameters, ρ v represents the density of the metal vapor, ρ L represents the density of the liquid metal, V f,v represents the volume fraction of the vapor, V f,L represents the volume fraction of the liquid.

[0142] According to the energy conservation basic equation and the heat loss caused by evaporation, convection and surface radiation to the environment during the processing process, combined with formulas (4) and (7), the energy conservation equation is obtained:

[0143]

[0144] In formula (19), m represents the atomic mass of the metal workpiece material, k represents the gradient operator, represents the fluid velocity, p represents the density in the finite element region, C p represents the specific heat capacity in the finite element region, k represents the thermal conductivity in the finite element region, T0 represents the initial temperature in the finite element region, T represents the current temperature in the finite element region, a represents the absorption rate of the composite material to be simulated to the laser, L v represents the latent heat of vaporization, v e represents the recession velocity of the evaporation front, p l represents the liquid density, h represents the heat transfer coefficient, x represents the surface emissivity, k b represents the Boltzmann constant, S represents the surface heat source, g(t) represents the time distribution of the action of the laser pulse, and d represents the first set function.

[0145] Considering the recoil pressure of the melt, the Marangoni force, and the surface tension, the two-phase flow boundary can be represented as:

[0146]

[0147] In formula (20), the right three terms are respectively the expressions of the surface tension, the recoil force, and the Marangoni force of the fluid, wherein the vapor recoil pressure is about the saturated pressure of the vapor at the evaporation surface, b r represents the saturated pressure of the vapor at the evaporation surface, and the diffusion coefficient can be obtained from the Clausius-Clayperon relationship:

[0148]

[0149] The Marangoni force is caused by the radial surface tension gradient. The three forces are applied as volume forces to the fluid control equation, and equation (6) is rewritten as a momentum conservation equation:

[0150]

[0151] In formula (22), represents the gradient operator, represents the fluid velocity, p represents the density in the finite element region, p represents the liquid pressure in the finite element region, T represents the current temperature in the finite element region, m represents the dynamic viscosity in the finite element region, and I represents the unit matrix, represents the volume force, d represents the first set function, and f represents the second set function, represents the gravitational acceleration of the earth, represents the surface tension, represents the recoil force, represents the Marangoni force, and represents the normal vector.

[0152] Finally, combined with equations (17) (18) (19) (22), the three-dimensional solid heat transfer and two-phase flow level set model can be obtained. Based on the multi-physics simulation technology of Comsol Multiphysics, the model can be implemented in Comsol Multiphysics. The model can simulate the generation process of small holes in laser drilling of homogeneous materials, and has a solid theoretical basis.

[0153] For example, in COMSOL, the specific parameters of the material need to be given first to calculate the above simulation. Taking SiO2 as an example, the parameter table required for simulation is given, as shown in Table 1:

[0154] Table 1

[0155]

[0156]

[0157] According to the above equations (17) (18) (19) (22) and physical parameters, the finite element calculation simulation in COMSOL software is established. In COMSOL, the fluid heat transfer and two-phase flow level set module is selected, which includes the basic form of fluid mass conservation equation, momentum conservation equation, energy conservation equation and level set equation. Then, according to the above derivation, source terms are added to the fluid mass conservation equation, momentum conservation equation, energy conservation equation and level set equation.

[0158] The mass loss term (17) (18) in the mass conservation equation and the level set equation needs to add a weak contribution item under the node, wherein the mass loss amount The calculation is carried out by formula (16) under the condition that the temperature distribution of the finite element region is known.

[0159] The input of the laser heat source is realized by adding a heat source term under the node of fluid heat transfer, that is, the energy conservation equation needs to add a heat source term under the node of fluid heat transfer. The surface convection and thermal radiation to the environment can be added by software under the node of fluid heat transfer.

[0160] For the modification of the momentum conservation equation, the volume force is added under the node of the momentum equation. The Darcy friction force, surface tension, recoil force and Marangoni force of the fluid are realized by adding volume force.

[0161] Among them, the expression of Darcy friction force is:

[0162]

[0163] wherein B represents a liquid volume fraction, zeta represents a tiny amount preventing the formula from being divided by zero, which can be set to 0.001, A mush represents a paste zone constant. The friction is approximately 10^8 N in the solid zone, rapidly decreases at the melting point, and is essentially 0 in the liquid zone. The Darcy friction is mainly used to stabilize the finite element region representing the solid in the two-phase flow.

[0164] The expression of the surface tension is wherein sigma represents a surface tension coefficient of the liquid phase, and the surface curvature is calculated by the local gradient along the normal direction of the gas / liquid surface.

[0165] The expression of the recoil force is formula (21), the temperature T is a variable, and can be calculated by a thermal field. In COMSOL, the expression of the action of the recoil force can be added on the two-phase flow interface.

[0166] The expression of the Marangoni force is which can also be added on the two-phase flow interface by multiplying a delta function.

[0167] The final simulation result is shown in Figure 5 , the process of forming a small hole of a composite material can be simulated, and the melt flow velocity field can be seen.

[0168] The cooling process can also be seen in the calculation result, wherein the cooling process produces the phenomenon of melt material backflow to the bottom of the small hole in the processing area. The comparison chart of the actual experiment can also find that the material melts and flows due to various forces and finally condenses on the wall and bottom of the small hole, which indicates that the simulation is similar to the actual laser drilling process, and the forming process of the material small hole can be simulated in detail.

[0169] The embodiment of the present application couples fluid heat transfer by using the two-phase flow-level set method to perform fluid dynamics simulation, and reproduces the laser selective melting process. The laser selective melting process can predict the shape generation process of a small hole of a composite material under laser irradiation, melt flow, and the accumulation condition after melt condensation under the condition that the thermal conductivity of each layer of the composite material is different, thereby improving the efficiency of laser drilling.

[0170] In one embodiment, a laser drilling method is provided, which is applied to a composite material laser drilling hole type prediction method, comprising: determining a first drilling parameter of a predicted laser drilling hole type, then adjusting a second drilling parameter according to the first drilling parameter, and performing laser drilling according to the adjusted second drilling parameter. The first drilling parameter is a drilling parameter predicted by simulation, and the second drilling parameter is a drilling parameter of a laser drilling device. By adjusting the second drilling parameter of the laser drilling device by using the first drilling parameter predicted by simulation, the accuracy and efficiency of laser drilling can be improved.

[0171] Figure 6 Figure 1 is a structural schematic diagram of a prediction device for a laser drilling hole shape of a composite material provided by the present application, referring to Figure 6 The embodiment of the present application provides a prediction device for a laser drilling hole shape of a composite material, which comprises a construction module 601, a first determination module 602, a second determination module 603 and a prediction module 604.

[0172] The construction module 601 is used for constructing a geometric model of a composite material to be simulated.

[0173] The first determination module 602 is used for determining boundary conditions of the geometric model and determining a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model.

[0174] The second determination module 603 is used for determining a heat transfer coefficient of the composite material to be simulated in the geometric model according to a rectangular wave function and a thickness of periodic arrangement of the composite material to be simulated.

[0175] The prediction module 604 is used for performing grid division on the geometric model to obtain a plurality of grid regions and predicting a laser drilling hole shape according to a set parameter of each grid region.

[0176] The embodiment of the present application provides a prediction device for a laser drilling hole shape of a composite material, which constructs a geometric model of a composite material to be simulated, determines boundary conditions of the geometric model and determines a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model, determines a heat transfer coefficient of the composite material to be simulated in the geometric model according to a rectangular wave function and a thickness of periodic arrangement of the composite material to be simulated, performs grid division on the geometric model to obtain a plurality of grid regions and predicts a laser drilling hole shape according to a set parameter of each grid region. The present application couples fluid heat transfer by using a two-phase flow-level set method to perform fluid dynamics simulation on a laser selective melting process, can predict a small hole shape generation process, melt flow and melt condensation and accumulation of a composite material under laser irradiation in consideration of different heat transfer coefficients of each layer of the composite material, and thus improves the efficiency of laser drilling.

[0177] In one embodiment, the second determination module 603 is specifically configured to

[0178] determine the rectangular wave function according to a radial heat transfer coefficient, an axial heat transfer coefficient and a single-layer thickness of the composite material to be simulated;

[0179] perform modulus operation on the thickness of periodic arrangement of the composite material to be simulated and coordinate information corresponding to the composite material to be simulated;

[0180] determine a heat transfer coefficient of the composite material to be simulated in the geometric model according to the modulus operation result and the rectangular wave function.

[0181] In one embodiment, the prediction module 603 is specifically configured to:

[0182] determine a meshing parameter of the geometric model;

[0183] mesh the geometric model according to the meshing parameter to obtain a plurality of mesh regions;

[0184] predict a laser drilling hole shape according to a temperature, a velocity, a pressure and a phase composition of each mesh region.

[0185] In one embodiment, the first determination module 602 is specifically configured to:

[0186] determine an initial condition, a boundary heat source condition and a two-phase flow level set boundary condition of the geometric model.

[0187] In one embodiment, the first determination module 602 is specifically configured to:

[0188] determine a mass conservation equation, a momentum conservation equation, an energy conservation equation and a level set equation of the fluid;

[0189] determine the three-dimensional solid heat transfer and two-phase flow level set model according to the mass conservation equation, the momentum conservation equation, the energy conservation equation and the level set equation.

[0190] In one embodiment, the first determination module 602 is specifically configured to:

[0191] determine the mass conservation equation according to a fluid velocity, a first set function, a mass loss amount of gasification of the composite material to be simulated, a density of metal vapor and a density of liquid metal.

[0192] In one embodiment, the first determination module 602 is specifically configured to:

[0193] determine the momentum conservation equation according to a fluid velocity, a body force, a unit matrix, a gravitational acceleration of the earth, a surface tension, a recoil force, a Marangoni force, a first set function, a second set function and dynamic viscosity, density, temperature and liquid pressure in a finite element region.

[0194] In one embodiment, the first determination module 602 is specifically configured to:

[0195] The energy conservation equation is determined according to a fluid velocity, a density in a finite element region, a specific heat capacity, a temperature and a thermal conductivity, a liquid density, an absorptivity of a composite material to be simulated to laser, an evaporation latent heat, a recession velocity of an evaporation front, a heat transfer coefficient, a surface emissivity, a Boltzmann constant, a first set function, a surface heat source and an action time distribution of a laser pulse.

[0196] In one embodiment, the first determining module 602 is specifically configured to:

[0197] The level set equation is determined according to a level set parameter, a fluid velocity, a mass loss amount of a composite material to be simulated to be vaporized, a density of a metal vapor, a density of a liquid metal, a volume fraction of a vapor, a volume fraction of a liquid, a first set function and a second set function.

[0198] In one embodiment, the first determining module 602 is specifically configured to:

[0199] A mass conservation equation is:

[0200]

[0201] wherein, denotes a gradient operator, denotes a fluid velocity, and δ denotes a first set function, denotes a mass loss amount of a composite material to be simulated to be vaporized, and ρ v denotes a density of a metal vapor, and ρ L denotes a density of a liquid metal, denotes a normal vector;

[0202] A momentum conservation equation is:

[0203]

[0204] wherein, denotes a gradient operator, denotes a fluid velocity, ρ denotes a density in a finite element region, p denotes a liquid pressure in the finite element region, T denotes a current temperature in the finite element region, μ denotes a dynamic viscosity in the finite element region, and I denotes a unit matrix, denotes a volume force, δ denotes a first set function, and φ denotes a second set function, denotes a gravitational acceleration of the earth, denotes a surface tension, denotes a recoil force, denotes a Marangoni force, and denotes a normal vector;

[0205] An energy conservation equation is:

[0206]

[0207] in, Represents the gradient operator, C represents the fluid velocity, ρ represents the density in the finite element region, and C represents the density in the finite element region. p Let represent the specific heat capacity in the finite element region, k represent the thermal conductivity in the finite element region, T0 represent the initial temperature in the finite element region, T represent the current temperature in the finite element region, α represent the absorptivity of the composite material to be simulated for laser light, and L represent the specific heat capacity in the finite element region. v Represents the latent heat of vaporization, v e ρ represents the receding velocity of the evaporation front. l Let ξ represent the liquid density, h represent the heat transfer coefficient, ξ represent the surface emissivity, and k represent the surface emissivity. b Let represent the Boltzmann constant, S represent the surface heat source, g(t) represent the time distribution of the laser pulse, and δ represent the first set function;

[0208] Level set equation:

[0209]

[0210]

[0211] in, Represents the gradient operator, Let δ represent the fluid velocity, φ represent the first set function, and φ represent the second set function. ρ represents the mass loss during the gasification of the composite material being simulated, ε and γ represent the level set parameters, and ρ represents the mass loss during the gasification of the composite material being simulated. v ρ represents the density of a metal vapor. L V represents the density of liquid metal. f,v V represents the volume fraction of steam. f,L It indicates the volume fraction of the liquid.

[0212] Figure 7 An example is a schematic diagram of the physical structure of a laser hole-making device, such as... Figure 7 As shown, the laser drilling device may include: a processor 710, a communication interface 720, a memory 730, and a communication bus 740. The processor 710, communication interface 720, and memory 730 communicate with each other via the communication bus 740. The processor 710 can call logic instructions from the memory 730 to execute a method for predicting the laser drilling pattern of composite materials. This method includes:

[0213] Construct a geometric model of the composite material to be simulated;

[0214] determine boundary conditions of the geometric model, and determine a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model;

[0215] determine a heat transfer coefficient of the composite material in the geometric model according to a rectangular wave function and a thickness of a periodic layup of the composite material to be simulated;

[0216] divide the geometric model into a plurality of grid regions, and predict a laser drilling profile according to a set parameter of each grid region.

[0217] Alternatively, the processor 710 can invoke the logical instructions in the memory 730 to perform a laser drilling method, which includes:

[0218] determine a first drilling parameter of the predicted laser drilling profile;

[0219] adjust a second drilling parameter according to the first drilling parameter, and perform laser drilling according to the adjusted second drilling parameter.

[0220] In addition, the logical instructions in the memory 730 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0221] On the other hand, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the prediction method of the composite material laser drilling profile provided by the above-mentioned methods, which includes:

[0222] constructing a geometric model of a composite material to be simulated;

[0223] determine boundary conditions of the geometric model, and determine a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model;

[0224] determine a heat transfer coefficient of the composite material in the geometric model according to a rectangular wave function and a thickness of a periodic layup of the composite material to be simulated;

[0225] Grid the geometry model to obtain a plurality of grid regions, and predict a laser drilling hole type according to a set parameter of each grid region.

[0226] Alternatively, the computer program is executed by a processor to implement the laser drilling method provided by the above-mentioned method, and the method comprises:

[0227] Determine the first drilling parameter of the predicted laser drilling hole type;

[0228] Adjust the second drilling parameter according to the first drilling parameter, and perform laser drilling according to the adjusted second drilling parameter.

[0229] The device embodiments described above are only illustrative, wherein the units illustrated as separate components can or can not be physically separated, and the components illustrated as units can or can not be physical units, i.e., they can be located in one place or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0230] From the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and necessary universal hardware platforms, and of course, can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of software products, which can be stored in a computer readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and include a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0231] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of predicting a laser drilling hole profile of a composite material, characterized by, The method comprises the following steps: constructing a geometric model of a composite material to be simulated; determining boundary conditions of the geometric model and determining a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model; determining a heat transfer coefficient of the composite material to be simulated in the geometric model according to a rectangular wave function and a thickness of periodic arrangement of the composite material to be simulated; dividing the geometric model into a plurality of grid regions by grid division, and predicting a laser drilling hole type according to a set parameter of each grid region; the determination of the boundary conditions of the geometric model comprises: determining initial conditions, boundary heat source conditions and two-phase flow level set boundary conditions of the geometric model; the determination of the three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model comprises: determining a mass conservation equation, a momentum conservation equation, an energy conservation equation and a level set equation of the fluid; determining the three-dimensional solid heat transfer and two-phase flow level set model according to the mass conservation equation, the momentum conservation equation, the energy conservation equation and the level set equation; the three-dimensional solid heat transfer and two-phase flow level set model comprises: mass conservation equation: ； wherein, denotes the gradient operator, denotes the fluid velocity, denotes a first set function, denotes the mass loss of the composite material to be simulated, denotes the density of the metal vapor, denotes the density of the liquid metal, denotes the normal vector; momentum conservation equation: ； wherein denotes the gradient operator, denotes the fluid velocity, denotes the density in the finite element region, denotes the liquid pressure in the finite element region, denotes the current temperature in the finite element region, denotes the dynamic viscosity in the finite element region, denotes the unit matrix, denotes the volume force, denotes a first set function, denotes a second set function, denotes the gravitational acceleration of the earth, denotes the surface tension, denotes the recoil force, denotes the Marangoni force, and denotes the normal vector; energy conservation equation: ； wherein, denotes the gradient operator, denotes the fluid velocity, denotes the density in the finite element region, denotes the specific heat capacity in the finite element region, denotes the thermal conductivity in the finite element region, denotes the initial temperature in the finite element region, denotes the current temperature in the finite element region, denotes the absorption rate of the composite material to be simulated for the laser, denotes the latent heat of evaporation, denotes the recession velocity of the evaporation front, denotes the liquid density, denotes the heat transfer coefficient, denotes the surface emissivity, denotes the Boltzmann constant, denotes the surface heat source, denotes the time profile of the action of the laser pulse, denotes a first set function; level set equation: ； wherein denotes the gradient operator, denotes the fluid velocity, denotes a first set function, denotes a second set function, denotes the mass loss of the composite material to be simulated, and denotes a level set parameter, denotes the density of the metal vapor, denotes the density of the liquid metal, denotes the volume fraction of the vapor, denotes the volume fraction of the liquid.

2. The method of predicting a laser drilling window for a composite material according to claim 1, wherein, the determination of the heat transfer coefficient of the composite material to be simulated in the geometric model according to the rectangular wave function and the thickness of periodic arrangement of the composite material to be simulated comprises: determining the rectangular wave function according to a radial heat transfer coefficient, an axial heat transfer coefficient and a single-layer thickness of the composite material to be simulated; modularizing the thickness of periodic arrangement of the composite material to be simulated and coordinate information corresponding to the composite material to be simulated; determining the heat transfer coefficient of the composite material to be simulated in the geometric model according to the modularization result and the rectangular wave function.

3. The method of predicting a laser drilling window for a composite material according to claim 1, wherein, the grid division of the geometric model into a plurality of grid regions by grid division, and the prediction of a laser drilling hole type according to a set parameter of each grid region comprises: determining grid division parameters of the geometric model; dividing the geometric model into a plurality of grid regions by grid division according to the grid division parameters; predicting a laser drilling hole type according to temperature, speed, pressure and phase composition of each grid region.

4. The method of predicting a laser drilling window for a composite material of claim 1, wherein, the determination of the mass conservation equation comprises: determining the mass conservation equation according to fluid speed, a first set function, a mass loss amount of gasification of the composite material to be simulated, a density of metal vapor and a density of liquid metal.

5. The method of predicting a laser drilling window for a composite material of claim 1, wherein, the determination of the momentum conservation equation comprises: determining the momentum conservation equation according to fluid speed, a body force, a unit matrix, a gravitational acceleration of the earth, a surface tension, a recoil force, a Marangoni force, a first set function, a second set function and dynamic viscosity, density, temperature and liquid pressure in a finite element region.

6. The method of predicting a laser drilling window for a composite material of claim 1, wherein, the determination of the energy conservation equation comprises: determining the energy conservation equation according to fluid speed, density, specific heat capacity, temperature and heat conductivity in a finite element region, liquid density, absorptivity of the composite material to be simulated to laser, latent heat of vaporization, recession speed of a vaporization front, heat transfer coefficient, surface emissivity, Boltzmann constant, a first set function, a surface heat source and action time distribution of a laser pulse.

7. The method of predicting a laser drilling window for a composite material of claim 1, wherein, A level set equation is determined, comprising: The level set equation is determined according to the level set parameter, the fluid velocity, the mass loss of the composite material to be simulated, the density of the metal vapor, the density of the liquid metal, the volume fraction of the vapor, the volume fraction of the liquid, a first set function, and a second set function.

8. A method of laser drilling, characterized by, The method for predicting the laser drilling hole pattern of the composite material according to any one of claims 1 to 7, comprising: determining a first drilling parameter of the predicted laser drilling hole pattern; adjusting a second drilling parameter according to the first drilling parameter, and performing laser drilling according to the adjusted second drilling parameter.

9. A device for predicting a laser drilling hole profile of a composite material, characterized in that, Comprise: a construction module, configured to construct a geometric model of a composite material to be simulated; a first determination module, configured to determine boundary conditions of the geometric model, and determine a three-dimensional solid heat transfer and two-phase flow level set model corresponding to the geometric model; a second determination module, configured to determine a heat transfer coefficient of the composite material to be simulated in the geometric model according to a rectangular wave function and a thickness of periodic laying of the composite material to be simulated; a prediction module, configured to divide the geometric model into a plurality of grid regions, and predict a laser drilling hole pattern according to set parameters of each grid region; the first determination module is further configured to determine initial conditions, boundary heat source conditions and two-phase flow level set boundary conditions of the geometric model; the first determination module is further configured to determine a mass conservation equation, a momentum conservation equation, an energy conservation equation and a level set equation of the fluid; and determine the three-dimensional solid heat transfer and two-phase flow level set model according to the mass conservation equation, the momentum conservation equation, the energy conservation equation and the level set equation; the three-dimensional solid heat transfer and two-phase flow level set model comprises: a mass conservation equation: ； wherein, denotes the gradient operator, denotes the fluid velocity, denotes a first set function, denotes the mass loss of the compound material to be simulated, denotes the density of the metal vapor, denotes the density of the liquid metal, denotes the normal vector; a momentum conservation equation: ； wherein denotes the gradient operator, denotes the fluid velocity, denotes the density in the finite element region, denotes the liquid pressure in the finite element region, denotes the current temperature in the finite element region, denotes the dynamic viscosity in the finite element region, denotes the unit matrix, denotes the volume force, denotes a first set function, denotes a second set function, denotes the gravitational acceleration of the earth, denotes the surface tension, denotes the recoil force, denotes the Marangoni force, and denotes the normal vector; an energy conservation equation: ； wherein, denotes the gradient operator, denotes the fluid velocity, denotes the density in the finite element region, denotes the specific heat capacity in the finite element region, denotes the thermal conductivity in the finite element region, denotes the initial temperature in the finite element region, denotes the current temperature in the finite element region, denotes the absorption rate of the composite material to be simulated for the laser, denotes the latent heat of evaporation, denotes the evaporation front retreat speed, denotes the liquid density, denotes the heat transfer coefficient, denotes the surface emissivity, denotes the Boltzmann constant, denotes the surface heat source, denotes the action time distribution of the laser pulse, denotes a first set function; a level set equation: ； wherein denotes the gradient operator, denotes the fluid velocity, denotes a first set function, denotes a second set function, denotes the mass loss of the composite material to be simulated, and denotes a level set parameter, denotes the density of the metal vapor, denotes the density of the liquid metal, denotes the volume fraction of the vapor, denotes the volume fraction of the liquid.

10. A laser drilling apparatus comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, The processor executes the program to realize the method for predicting the laser drilling hole pattern of the composite material according to any one of claims 1 to 7, or realize the laser drilling method according to claim 8. 11.A non-transitory computer-readable storage medium having stored thereon a computer program. The computer program is executed by the processor to realize the method for predicting the laser drilling hole pattern of the composite material according to any one of claims 1 to 7, or realize the laser drilling method according to claim 8.

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