Carbon-carbon composite material array hole laser processing step-by-step heat accumulation solving method

Abstract

The invention discloses a step-by-step solution heat accumulation method for laser processing of carbon-carbon composite material array holes, belongs to the field of material processing numerical simulation, and relates to a step-by-step solution-based carbon-carbon composite material array hole laser processing heat accumulation analysis method. According to the method, a single-hole high-precision ablation model considering the actual physical heat dissipation process is constructed on the basis of a single-hole machining temperature field obtained by solving a high-precision finite element in the single-hole machining process and COMSOL Multiphysics software. In the single-hole machining process, time-varying heat distribution serves as input to be applied to the array hole machining model, and the time cost of calculation in the array hole machining process is reduced on the premise that the calculation precision is guaranteed. And finally, solving the carbon-carbon composite material array hole laser processing model to obtain the temperature field change in the array hole laser processing process. According to the method, the calculation speed can be remarkably increased on the premise that the solving precision is guaranteed, and high-precision and high-efficiency laser processing of the carbon-carbon composite material is achieved.

Description

Technical Field

[0001] This invention belongs to the field of numerical simulation of materials processing, and relates to a method for thermal accumulation analysis of laser processing of array holes in carbon-carbon composite materials based on step-by-step solution. Background Technology

[0002] Carbon-carbon composites are superior materials with low density, low coefficient of thermal expansion, and unique high-temperature mechanical properties. With the widespread application of carbon-carbon composites in the aerospace field, thin-walled, high-density array-hole carbon-carbon composite components, exemplified by ion engine gate assemblies, have emerged. Although most composite components utilize near-net-shape forming processes, the demand for high-quality and efficient processing technologies for carbon-carbon composites is increasingly prominent to meet dimensional accuracy requirements and improve performance. The hardness, brittleness, and strong anisotropy of carbon-carbon composites make it difficult to achieve high-quality and efficient processing using traditional methods. In contrast, laser processing, known for its high precision, non-impact characteristics, and high processing flexibility, provides a feasible solution for the manufacturing of carbon-carbon composite parts.

[0003] Given the high manufacturing cost of carbon-carbon composite materials, relying solely on experimental research requires significant human and material resources and makes it difficult to efficiently and accurately obtain the temperature field during array hole processing under different technological conditions. Accurately predicting the heat accumulation and thermal interaction processes during array hole processing using finite element simulation is crucial not only for achieving high-quality and efficient laser processing of array holes in carbon-carbon composite materials but also for providing a reference for the laser manufacturing of complex structures in advanced materials.

[0004] Existing technical literature 1, the invention patent "Simulation Method of Temperature Field for Laser Processing of Alloy Mesh Materials" by Zhai Zhaoyang et al. (Patent Publication No. CN119889535A), simulated the temperature field of laser-processed alloy mesh materials, obtaining the temperature changes on the workpiece surface and the trend and direction of heat conduction. However, it did not take into account the temperature changes caused by material removal. Existing technical literature 2, the invention patent "Finite Element Simulation Method, Equipment and Storage Medium for Laser Through-holes" by Yuan Songmei et al. (Patent Publication No. CN115510700A), simulated the formation process of through-holes during laser processing of structural components based on finite element analysis. However, the proposed method is for processing single holes and is difficult to directly apply to the laser processing analysis of array holes. Furthermore, accurately describing the temperature changes during the laser processing of carbon-carbon composite materials undoubtedly requires considering many actual physical processes, such as the heat carried away by the phase transformation during the ablation of carbon-carbon composite materials, the radiative heat during processing, and the cooling effect brought by the airflow during processing. For large-scale array hole processing, the time cost of full-precision simulation calculation is prohibitive. Therefore, there is an urgent need for a finite element simulation method for carbon-carbon composite materials that can comprehensively consider the actual physical process and ensure the solution speed, so as to achieve high-precision and high-efficiency acquisition of the temperature field during the laser processing of array holes in carbon-carbon composite materials. Summary of the Invention

[0005] This invention aims to achieve high-precision and efficient prediction of heat accumulation during laser machining of arrayed holes in carbon-carbon composite materials. A step-by-step heat accumulation analysis method is proposed for laser machining of arrayed holes. This invention solves the problem of difficulty in solving the large scale difference between single-hole simulation and arrayed hole simulation by using a step-by-step method of high-precision solution of the single-hole temperature field and rapid solution of the global arrayed hole temperature field, thus achieving high-precision and efficient heat accumulation analysis of laser machining of arrayed holes in carbon-carbon composite materials. Based on high-precision single-hole ablation simulation, time-varying heat results are extracted from single-hole machining and applied to arrayed hole modeling to obtain the heat accumulation changes of the entire workpiece during arrayed hole laser machining, fully revealing the temperature field distribution throughout the entire arrayed hole machining process. Based on COMSOL Multiphysics software, a high-precision single-hole ablation model considering the actual physical heat dissipation process is constructed; the time-varying heat distribution during single-hole machining is used as input to the arrayed hole machining model to reduce the computational time cost during arrayed hole machining; the carbon-carbon composite material arrayed hole laser machining model is solved to obtain the temperature field changes during arrayed hole laser machining. This method can significantly improve the calculation speed while ensuring the accuracy of the solution, and has important guiding significance for realizing high-precision and high-efficiency laser processing of carbon-carbon composite materials.

[0006] The technical solution adopted in this invention is a step-by-step solution for heat accumulation in laser processing of array holes in carbon-carbon composite materials. The method is characterized by extracting the temperature field of a single hole from a high-precision finite element solution of the single hole processing process and applying the single hole temperature field result to the finite element simulation of the array hole, which significantly improves the computational efficiency of the model while reducing the difficulty of model solution.

[0007] The specific steps of this method are as follows:

[0008] Step 1: Create an equivalent homogeneous model of carbon-carbon composite materials.

[0009] To address the significant scale difference between the fiber (~7μm) and the model domain size (2000μm×2000μm×600μm) during single-pore simulation calculations, an equivalent homogeneous finite element model of carbon-carbon composite materials based on the principle of composite material mixing was established. The equivalent physical property parameters of the carbon-carbon composite materials were obtained by calculating the weighted average of the fiber and matrix volume fractions, as shown in equations (1) to (4).

[0010]

[0011] Among them, V f and V m ρ represents the volume fraction of the fiber and the matrix, respectively. f and ρ m C fand C m T f and T m H f and H m These represent the density, specific heat capacity, vaporization temperature, and latent heat of vaporization of the fiber and matrix, respectively, while ρ e C e T e and H e These represent the equivalent density, specific heat capacity, vaporization temperature, and latent heat of vaporization of carbon-carbon composite materials, respectively.

[0012] Furthermore, the anisotropy of carbon-carbon composites should be considered in heat transfer analysis. This anisotropy manifests in the difference between the axial and radial thermal conductivity of the fibers. For carbon-carbon composites, the total thermal resistance K along the fiber radial direction is... r This can be considered as a series combination of the thermal resistances of the fiber and the matrix, and the total thermal resistance along the fiber axis K a It can be regarded as a parallel combination of the thermal resistance of the fiber and the matrix, as shown in equation (5).

[0013]

[0014] Among them, K f and K m These represent the thermal conductivity of carbon fiber and carbon matrix, respectively.

[0015] A finite element model of carbon-carbon composite material was established using COMSOL Multiphysics simulation software. The model consists of six layers of material with a thickness of 0.1 mm and is used to simulate the fiber arrangement of [0° / 60° / -60°] laminated carbon-carbon composite material. This arrangement differs from the traditional 0° / 90° fiber layup, which defines the thermal conductivity in an orthogonal coordinate system.

[0016] To achieve fiber alignment, the x-axis in a spatial orthogonal coordinate system is used as the parallel fiber direction, defining the single-layer thermal conductivity of the top and bottom 0° oriented fibers. Two rotating coordinate systems are constructed by rotating the x-axis by 60° and -60° respectively, thus defining the thermal conductivity of the middle four layers of 60° and -60° oriented fibers. A free triangular element is used to generate the material surface mesh. Subsequently, a sweep operation is used to delineate the mesh of the entire geometry, and local mesh refinement is performed in the laser-affected area to improve solution accuracy.

[0017] Step 2: Establish a pulsed laser heat source model.

[0018] The low transmittance of carbon materials to near-infrared wavelengths indicates that the interaction between the laser and the carbon-carbon composite material occurs on the material surface. Therefore, in the numerical simulation of the pulsed laser single-hole model, the laser beam can be regarded as a Gaussian distributed thermal pulse propagating along a specified path, as shown in equation (6):

[0019]

[0020] Where η is the material absorption coefficient of the laser, P is the laser power, r0 is the laser spot radius, x and y are spatial coordinates, R0 is the radius of the machining hole, v0 is the laser scanning speed, t is time, and ONOFF is the event physics field in COMSOL Multiphysics, with a value of 1 or 0 representing the continuous state and the off state of the pulse, respectively.

[0021] Step 3: Construct the governing equations for the single-hole machining model.

[0022] The laser ablation process of carbon-carbon composite materials follows the law of conservation of energy, and the governing equation is as shown in equation (7):

[0023]

[0024] Where, q i Let be the heat flux component, n be the unit vector perpendicular to the surface, Q be the unit heat generation rate of the internal heat source, ρ be the density, C be the specific heat capacity, T be the material temperature, and t be the time of action.

[0025] According to Fourier's law, we have equation (8):

[0026]

[0027] Where K is the thermal conductivity.

[0028] Combining equations (7) and (8), a three-dimensional nonlinear transient heat transfer control equation for laser processing of carbon-carbon composite materials in Cartesian coordinates is constructed:

[0029]

[0030] Among them, K x K y With K z These represent the thermal conductivity of the carbon-carbon composite material in the x, y, and z directions, respectively.

[0031] Step 4: Set boundary conditions for single-hole machining process.

[0032] To ensure the uniqueness of the solution, the following three types of boundary conditions are set during the solution process, as shown in equations (10) to (12):

[0033] Type I boundary conditions are:

[0034]

[0035] The initial temperature of the model was the ambient temperature of 293K.

[0036] Type II boundary conditions in the laser-processed region include both laser heat flux density and air convection heat transfer. The coaxial assist gas used in laser processing generates a cooling effect; therefore, forced convection heat transfer is employed on the laser-processed surface.

[0037]

[0038] Among them, the convective heat transfer coefficient h1 is taken as an empirical value. , The ambient temperature.

[0039] Type III boundary conditions are the heat exchange boundary conditions caused by carbon-carbon composite materials during solid-gas phase transition:

[0040]

[0041] Where dm / dt represents the rate of change of phase transition mass per unit time.

[0042] Step 5: Solving and Deriving the Temperature Field in a Single Hole

[0043] Input laser processing parameters and solve the model. Obtain the temperature distribution of a single hole in the laser-ablated carbon-carbon composite material under the input processing parameter combination. Then, export the temperature field of the single hole.

[0044] Step 6: Establish the simulation model and control equations for laser processing of arrayed holes.

[0045] In the process of machining array holes, the thickness of the carbon-carbon composite material differs from its length and width by nearly an order of magnitude, thus the temperature gradient along the thickness direction is negligible. The main concern when machining array holes in thin plates is the in-plane temperature variation of the carbon-carbon composite material. Therefore, a two-dimensional approximation method is used to analyze the laser machining process of array holes in carbon-carbon composite materials.

[0046] A macroscopic homogeneous finite element simulation model of carbon-carbon composite material was established using COMSOL Multiphysics software, and the maximum mesh size was set to 30 μm to ensure calculation accuracy.

[0047] To analyze the heat transfer process in the laser processing of arrayed holes in carbon-carbon composite materials, the temperature field of a single hole obtained in step 5 is imported into the arrayed hole simulation as a time-varying temperature field. This operation essentially transforms the boundary conditions from Neumann conditions to Dirichlet conditions, and its governing equation is as shown in equation (13):

[0048]

[0049] Among them, T b (x,y,t) is a temperature field that varies with time. It describes the process of heat diffusion in space. Here, K is the gradient operator, and K is the thermal conductivity of the material.

[0050] In a two-dimensional Cartesian coordinate system, for anisotropic carbon-carbon composite materials, the equation can be expressed as, equation (14):

[0051]

[0052] Step 7: Set boundary conditions for the array hole machining process.

[0053] In the initial stage of the entire processing, the workpiece temperature is equal to room temperature, therefore the initial conditions are:

[0054]

[0055] In step 4, the cooling effect caused by the coaxial laser airflow and the solid-gas phase change of the carbon-carbon composite material has been considered. The un-irradiated surface of the workpiece undergoes convective heat transfer with the environment and radiates heat outward. Therefore, the boundary conditions are:

[0056]

[0057] Where ε is the surface emissivity and σ is the Stefan-Boltzmann constant.

[0058] Step 8: Solve the model.

[0059] By inputting laser processing parameters and solving the model, the temperature field of laser-processed carbon-carbon composite material array holes under different processing parameter conditions is finally obtained.

[0060] The beneficial effects of this invention are as follows: Addressing the challenge of balancing accuracy and efficiency in simulating the temperature field during laser processing of arrayed holes in carbon-carbon composite materials, this invention presents a step-by-step heat accumulation method for laser processing of arrayed holes in carbon-carbon composite materials. This method considers the heat changes inherent in the actual physical processes during material processing. Through a step-by-step solution strategy—high-precision solution of the temperature field at a single hole followed by rapid solution of the temperature field across the entire array of holes—it ensures the accuracy of single-hole temperature calculations while significantly reducing the overall solution difficulty of the model. This substantially improves the solution efficiency for large-size arrayed hole models, achieving high-precision and high-efficiency acquisition of the temperature field during laser processing of arrayed holes in carbon-carbon composite materials. Attached Figure Description

[0061] Figure 1 This is a flowchart of a step-by-step heat accumulation solution method for laser processing of array holes in carbon-carbon composite materials.

[0062] Figure 2 Finite element analysis results of temperature distribution during laser processing of a single hole in a carbon-carbon composite material at different time points.

[0063] Figure 3 The finite element method (FEM) results and experimental results are compared to show the temperature distribution during laser processing of array holes in carbon-carbon composite materials at different time points. Figures a), b), e), and f) show the experimentally measured temperature fields, while figures c), d), g), and h) show the temperature fields obtained through step-by-step simulation. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0065] Appendix Figure 1 This is a flowchart illustrating a step-by-step solution method for thermal accumulation in the laser machining of arrayed holes in carbon-carbon composite materials. This invention employs a step-by-step solution method—high-precision solution of the single-hole temperature field followed by rapid solution of the global arrayed hole temperature field—to achieve high-precision and efficient thermal accumulation analysis in the laser machining of arrayed holes in carbon-carbon composite materials. This method addresses the problem of difficulty in solving the problem due to the significant scale difference between the single-hole simulation and the arrayed hole simulation. Based on COMSOL Multiphysics software, a high-precision ablation model of the single hole is constructed, taking into account the actual physical heat dissipation process. Then, the time-varying heat distribution during the single-hole machining process is used as input to the arrayed hole machining model to reduce the computational time cost during the arrayed hole machining process. Finally, the laser machining model of the carbon-carbon composite material arrayed holes is solved to obtain the temperature field changes during the laser machining process. This method significantly improves the computational speed while ensuring solution accuracy, and has important guiding significance for achieving high-precision and efficient laser machining of carbon-carbon composite materials.

[0066] This embodiment uses a quasi-continuous laser processing of a square carbon-carbon composite material sample with a 6×6 array of holes as an example to illustrate the simulation process of this method in detail.

[0067] The specific steps of this method are as follows:

[0068] Step 1: Create an equivalent homogeneous model of carbon-carbon composite materials.

[0069] First, an equivalent homogeneous geometric model of the carbon-carbon composite material is established in the finite element software COMSOL Multiphysics. Then, in the main interface of the software, select "Model Wizard," choose "3D" for the spatial dimension, and create a model with a length l of 2mm, a width b of 2mm, and a single-layer thickness h. s It is a geometric model with a thickness of 0.1mm, composed of 6 layers of stacked materials, and a total thickness h of 0.6mm.

[0070] Next, the equivalent density, specific heat capacity, vaporization temperature and latent heat of vaporization of carbon-carbon composite materials are calculated using formulas (1) to (4).

[0071]

[0072] The thermal conductivity of carbon fiber and carbon matrix is ​​calculated using formula (5).

[0073]

[0074] The material parameters of the equivalent homogeneous model were calculated using the above formulas, as shown in Table 1. Furthermore, based on the fiber arrangement of the [0° / 60° / -60°] laminated carbon-carbon composite material, the x-axis in a spatial orthogonal coordinate system was used as the parallel fiber direction to define the single-layer thermal conductivity of the top and bottom 0° oriented fibers. Two rotating coordinate systems were constructed by rotating the x-axis by 60° and -60° respectively, thereby defining the thermal conductivity of the middle four layers of 60° and -60° oriented fibers. Free triangular elements were used to generate the material surface mesh. To ensure calculation accuracy, the mesh near the laser scanning path was refined, with the maximum mesh size in the refined area set to 15 μm, and the mesh size in the remaining areas selected as "normal". A sweep operation was then performed, with one mesh per layer thickness direction, to obtain the mesh for the entire geometry.

[0075] Table 1 Material parameters of the equivalent homogeneous model

[0076]

[0077] Step 2: Establish a pulsed laser heat source model.

[0078] The low transmittance of carbon materials to near-infrared wavelengths indicates that the interaction between the laser and the carbon-carbon composite material occurs on the material surface. Therefore, in the numerical simulation of the pulsed laser single-hole model, the laser beam can be regarded as a Gaussian distributed thermal pulse propagating along a specified path, expressed by formula (6).

[0079]

[0080] The material absorption coefficient η of the laser is 0.875, the laser spot radius r0 is 38.6μm, and the processing hole radius R0 is 0.5mm.

[0081] Step 3: Construct the governing equations for the single-hole machining model.

[0082] Combining equations (7) and (8), a three-dimensional nonlinear transient heat transfer control equation for laser processing of carbon-carbon composite materials in Cartesian coordinates is constructed, which is expressed by equation (9).

[0083]

[0084] Step 4: Set boundary conditions for single-hole machining process.

[0085] To ensure the uniqueness of the solution, the following three types of boundary conditions were set during the solution process.

[0086] The initial temperature of the model is set to the ambient temperature of 293K. The type I boundary conditions can then be expressed by formula (10).

[0087]

[0088] Type II boundary conditions refer to the boundary conditions of the laser processing area, which include laser heat flux density and air convection heat transfer. The coaxial assist gas used in laser processing will produce a cooling effect, therefore forced convection heat transfer is used on the laser processing surface, which can be expressed by formula (11).

[0089]

[0090] Among them, the convective heat transfer coefficient h1 is taken as an empirical value. .

[0091] Type III boundary conditions are the heat exchange boundary conditions caused by carbon-carbon composite materials during solid-gas phase transition, and can be expressed by formula (12).

[0092]

[0093] Step 5: Solving and Deriving the Temperature Field in a Single Hole

[0094] Input laser processing parameters and solve the model. Obtain the temperature distribution of a single pore in the laser-ablated carbon-carbon composite material under this combination of processing parameters, such as... Figure 2 As shown. Next, the temperature field of the single hole is derived.

[0095] Step 6: Establish the simulation model and control equations for laser processing of arrayed holes.

[0096] Enter the software's main interface, select "Model Wizard," choose "2D" for the spatial dimension, and create a geometric model with an overall size of 40mm × 40mm. Use a free triangular element mesh to mesh the geometric model. To ensure computational accuracy, the maximum mesh size is set to 30μm.

[0097] To analyze the heat transfer process in the laser processing of arrayed holes in carbon-carbon composite materials, the temperature field of a single hole obtained in step 5 is imported into the arrayed hole simulation as a time-varying temperature field. This operation essentially transforms the boundary conditions from Neumann conditions to Dirichlet conditions, and its governing equation is shown in equation (14):

[0098]

[0099] Step 7: Set boundary conditions for the array hole machining process.

[0100] In the initial stage of the entire processing, the workpiece temperature is equal to room temperature, therefore the initial conditions are expressed by formula (15).

[0101]

[0102] In step 4, the cooling effect caused by the coaxial laser airflow and the solid-gas phase change of the carbon-carbon composite material has been considered. The un-irradiated surface of the workpiece undergoes convective heat transfer with the environment and radiates heat outward. Therefore, the boundary conditions are expressed by formula (16).

[0103]

[0104] Wherein, the surface emissivity ε is taken as 0.87, and the Stefan-Boltzmann constant σ is... for.

[0105] Step 8: Solve the model.

[0106] By inputting laser processing parameters and solving the model, the temperature field of laser-processed carbon-carbon composite material array holes under different processing parameter conditions is finally obtained.

[0107] Figure 3 This paper compares the finite element method (FEM) results with experimental results for the temperature distribution during laser processing of array holes in carbon-carbon composite materials at different time points. Figures (a), (b), (e), and (f) show the experimentally measured temperature fields, while figures (c), (d), (g), and (h) show the temperature fields obtained through step-by-step simulation. Figure 3 As shown, the temperature distribution of the workpiece space obtained by simulation and experiment are in good agreement. When t=0.1s, t=1.5s, t=3.4s, and t=15.2s, the highest temperatures measured in the experiment are 2078K, 1820K, 1898K, and 1799K, respectively, while the simulation results are 2334K, 2013K, 2120K, and 2004K, respectively. The relative errors corresponding to the highest temperatures are 12.3%, 10.6%, 11.7%, and 11.4%, respectively, and the average relative error is 11.5%.

Claims

1. A step-by-step method for solving heat accumulation in laser processing of arrayed holes in carbon-carbon composite materials, characterized in that, This method is based on the single-hole machining temperature field obtained by high-precision finite element solution of single-hole machining process. The single-hole temperature field results are extracted and applied to array-level finite element simulation, which significantly improves the computational efficiency of the model while reducing the difficulty of model solution. The specific steps of the method are as follows: Step 1: Create an equivalent homogeneous model of carbon-carbon composite materials; To address the significant scale difference between the ~7μm fiber and the 2000μm×2000μm×600μm model domain size during single-pore simulation calculations, an equivalent homogeneous finite element model of carbon-carbon composite material was established based on the composite material mixing rules. The equivalent physical property parameters of the carbon-carbon composite material were obtained by calculating the weighted average of the fiber and matrix volume fractions, as shown in equations (1) to (4). Among them, V f and V m ρ represents the volume fraction of the fiber and the matrix, respectively. f and ρ m C f and C m T f and T m H f and H m These represent the density, specific heat capacity, vaporization temperature, and latent heat of vaporization of the fiber and matrix, respectively, while ρ e C e T e and H e These represent the equivalent density, specific heat capacity, vaporization temperature, and latent heat of vaporization of carbon-carbon composite materials, respectively. Furthermore, the anisotropy of carbon-carbon composites should also be considered in heat transfer analysis; this anisotropy is mainly reflected in the difference between the axial and radial thermal conductivity of the fibers; for carbon-carbon composites, the total thermal resistance K along the fiber axis is... a It can be considered as a parallel combination of the thermal resistance of the fiber and the matrix, while the total thermal resistance K along the radial direction of the fiber is... r It can then be regarded as a series combination of the thermal resistance of the fiber and the matrix, as shown in equation (5); Among them, K f and K m These represent the thermal conductivity of carbon fiber and carbon matrix, respectively. A finite element model of carbon-carbon composite material was established using COMSOL Multiphysics simulation software. The model consists of six layers of material with a thickness of 0.1 mm, used to simulate the fiber arrangement of [0° / 60° / -60°] laminated carbon-carbon composite material. This arrangement differs from the traditional 0° / 90° fiber layup, which defines the thermal conductivity in an orthogonal coordinate system. To achieve fiber alignment, the x-axis in a spatial orthogonal coordinate system is used as the parallel fiber direction, defining the single-layer thermal conductivity of the top and bottom 0° oriented fibers. Two rotating coordinate systems are constructed by rotating the x-axis by 60° and -60° respectively, thereby defining the thermal conductivity of the middle four layers of 60° and -60° oriented fibers. Free triangular elements are used to generate the material surface mesh. Subsequently, a sweep operation is used to delineate the mesh of the entire geometry, and local mesh refinement is performed on the laser-affected area to improve the solution accuracy. Step 2: Establish a pulsed laser thermal source model; The low transmittance of carbon materials to near-infrared wavelengths indicates that the interaction between the laser and the carbon-carbon composite material occurs on the material surface; therefore, when performing numerical simulation of the pulsed laser single-hole model, the laser beam can be regarded as a Gaussian distributed thermal pulse propagating along a specified path, as shown in equation (6): Where η is the material absorption coefficient of the laser, P is the laser power, r0 is the laser spot radius, x and y are spatial coordinates, R0 is the radius of the machining hole, v0 is the laser scanning speed, t is time, and ONOFF is the event physics field in COMSOL Multiphysics, with a value of 1 or 0 representing the continuous state and the off state of the pulse, respectively. Step 3: Construct the governing equations for the single-hole machining model; The laser ablation process of carbon-carbon composite materials follows the law of conservation of energy, as shown in equation (7): Where q i Let be the heat flux component, n be the unit vector perpendicular to the surface, Q be the unit heat generation rate of the internal heat source, ρ be the density, C be the specific heat capacity, T be the material temperature, and t be the time of action. According to Fourier's law, we have equation (8): Where K is the thermal conductivity; Combining equations (7) and (8), a three-dimensional nonlinear transient heat transfer control equation for laser processing of carbon-carbon composite materials in Cartesian coordinates is constructed: Among them, K x K y With K z These represent the thermal conductivity of the carbon-carbon composite material in the x, y, and z directions, respectively. Step 4: Set boundary conditions for single-hole machining process; To ensure the uniqueness of the solution, the following three types of boundary conditions are set during the solution process, as shown in equations (10) to (12): Type I boundary conditions are: The initial temperature of the model was the ambient temperature of 293K; Type II boundary conditions include laser heat flux density and air convection heat transfer in the laser processing area; the coaxial auxiliary gas used in laser processing will produce a cooling effect, so forced gas convection heat transfer is used on the laser processing surface; The convective heat transfer coefficient h1 is taken as an empirical value. ,in The ambient temperature; Type III boundary conditions are heat exchange boundary conditions caused by carbon-carbon composite materials during solid-gas phase transition; Where dm / dt represents the rate of change of phase transition mass per unit time; Step 5: Solving and Deriving the Temperature Field in a Single Hole Input the laser processing parameters and solve the model; obtain the temperature distribution of a single hole in the laser ablation carbon-carbon composite material under the combination of processing parameters; then, export the temperature field of the single hole. Step 6: Establishment of simulation model and control equations for laser processing of arrayed holes; During the processing of array holes, the thickness of the carbon-carbon composite material differs from its length and width by nearly an order of magnitude, so the temperature gradient along the thickness direction can be ignored. However, the main concern when processing array holes in thin plates is the in-plane temperature change of the carbon-carbon composite material. Therefore, a two-dimensional approximation method is used to analyze the laser processing of array holes in carbon-carbon composite materials. A macroscopic homogeneous finite element model of carbon-carbon composite material was established using COMSOL Multiphysics software, and the maximum mesh size was set to 30 μm to ensure calculation accuracy. To analyze the heat transfer process in the laser processing of array holes in carbon-carbon composite materials, the single-hole temperature field obtained in step 5 is used as the time-varying temperature field and imported into the array hole simulation; this operation essentially transforms the boundary conditions from Neumann conditions to Dirichlet conditions, and its governing equation is as shown in equation (13): Among them, T b (x,y,t) is a temperature field that varies with time. Describe the process of heat diffusion in space. Here, K is the gradient operator, and K is the thermal conductivity of the material. In a two-dimensional Cartesian coordinate system, this equation can be expressed as equation (14): Step 7: Set boundary conditions for the array hole machining process; In the initial stage of the entire processing, the workpiece temperature is equal to room temperature, therefore the initial conditions are: In step 4, the cooling effect caused by the coaxial laser airflow and the solid-gas phase transition of the carbon-carbon composite material has been considered. The un-irradiated surface of the workpiece undergoes convective heat transfer with the environment and radiates heat outward. Therefore, the boundary conditions are: Where ε is the surface emissivity (~0.87). It is the Stefan-Boltzmann constant; Step 8: Solve the model; By inputting laser processing parameters and solving the model, the temperature field of laser-processed carbon-carbon composite material array holes under different processing parameter conditions is finally obtained.

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