Simulation method of laser ablation of fully braided CFRP under tangential airflow

Abstract

This invention discloses a simulation method for laser ablation of fully woven carbon fiber reinforced plastic (CFRP) under tangential airflow. This method proposes a mechanical erosion model for the dense structure of fully woven materials under high-speed tangential airflow and high-power laser density, while also considering the influence of vortex evolution in the ablation crater on oxygen mass transfer and mechanical erosion. By establishing a fluid-solid coupling model, this method simultaneously analyzes the resin pyrolysis reaction, the oxidation and sublimation erosion of carbon fibers and residual carbon, the mechanical erosion caused by the external tangential airflow, and the mechanical erosion generated by the internal pyrolysis gas during the laser ablation process. This method addresses the different contributions of CFRP to erosion at different stages of laser ablation. This method can reproduce the ablation process of CFRP by any form of laser within a certain flow rate range, providing a theoretical and simulation basis for high-power laser damage to composite materials under high-velocity tangential airflow.

Description

Technical Field

[0001] The present invention belongs to the field of laser processing and damage, and in particular relates to a simulation method for laser ablation of fully woven CFRP under tangential airflow. Background Art

[0002] Carbon fiber reinforced resin composites (CFRP) are layered composite materials with carbon fibers as reinforcement and resin as the matrix. CFRP has the characteristics of high specific strength, high specific modulus, high hardness, high temperature resistance, corrosion resistance, low expansion, good fatigue resistance, low specific gravity, and excellent mechanical properties. Fully woven CFRP, due to its higher strength and superior mechanical properties compared to unidirectional and orthogonal CFRP, is more widely used in aerospace and military weapon manufacturing, especially in the field of multi-purpose unmanned aerial vehicles. Existing missile interception is costly and has limited accuracy; high-energy laser weapons have the advantages of continuous tracking and strike, light-speed damage, and low cost. Therefore, it is crucial to conduct research on the laser ablation characteristics of fully woven CFRP under high-speed airflow.

[0003] Laser ablation of CFRP is an extremely complex physicochemical process, involving the pyrolysis of the resin, the reaction and flow of pyrolysis products, irreversible expansion and mechanical ablation caused by internal pressure, oxidation of residual carbon and carbon fibers, and the resulting changes in material strength, as well as the shielding effect of pyrolysis plume particles on the laser and the obstruction of oxygen mass transfer. If high-speed gas flows over the material surface, the ablation process also includes external mechanical ablation effects, the dynamic evolution of oxygen mass transfer, and temperature evolution caused by convective heat transfer on the material surface. When the temperature reaches the vaporization temperature of carbon, sublimation occurs on the material surface. Therefore, the damage process of laser ablation of CFRP under tangential airflow can be described as: pyrolysis, oxidation, internal mechanical ablation, external mechanical ablation, and sublimation. The intense processes involved in laser ablation of CFRP make quantifying the various contributions to the ablation process difficult through experimental studies. Consequently, numerical simulation has become an increasingly important analytical tool.

[0004] Existing numerical simulations primarily focus on studying CFRP laser cutting at low power, oxidation ablation at low flow rates, and external mechanical erosion at high flow rates. Few studies fully consider the contribution of each physical and chemical stage, and research on laser ablation of fully woven CFRP under tangential airflow is even more limited. The unique structure of fully woven materials exhibits more complex behavior during ablation than unidirectional and orthogonal structures, making thermophysical property parameters more difficult to quantitatively analyze. When studying oxidation ablation and external mechanical erosion, many studies directly calculate the oxygen concentration and boundary velocity in the fluid domain as constants, failing to accurately account for the variable distribution resulting from the evolution of the ablation pit. Currently, internal mechanical erosion of CFRP materials simply considers temperature evolution, without considering the stage-by-stage characteristics of internal mechanical erosion in combination with actual conditions. Specifically, as pyrolysis is complete, the internal mechanical erosion rate gradually approaches zero.

[0005] Therefore, it is necessary to develop a simulation method for laser ablation of fully woven CFRP under tangential airflow, and qualitatively and quantitatively analyze the stage-by-stage contributions of pyrolysis, oxidation, sublimation, external mechanical erosion, and internal mechanical erosion to the ablation process, so as to accurately determine the damage mechanism of laser on high-speed targets and realize the formulation of efficient laser strike strategies. Summary of the Invention

[0006] The purpose of the present invention is to provide a simulation method for laser ablation of fully braided CFRP under tangential airflow.

[0007] The technical solution to achieve the purpose of the present invention is: a simulation method for laser ablation of fully braided CFRP under tangential airflow, comprising the following steps:

[0008] Step 1: Use the volume averaging method to homogenize the density, constant pressure heat capacity, and thermal conductivity of the material;

[0009] Step 2: Establish the basic governing equations for the fluid and porous media domains based on the conservation theorems of momentum, mass, and energy, and use the moving mesh method to track the interface regression and ablation processes.

[0010] Step 3: Construct a dense structure physical model, track the changes in fluid velocity on the material surface within the ablation crater, map it to the material surface using the boundary similarity principle, and replace the velocity term in the original equation for correction;

[0011] Step 4: Based on the theory of dense structure, deduce and set the anisotropic thermal conductivity of the material;

[0012] Step 5: Consider the work done by the pressure change and viscous dissipation of the pyrolysis gas and add it to the porous media energy conservation equation for correction;

[0013] Step 6: Track the evolution of the temperature and pressure of the fluid on the surface of the material in the ablation crater, and calculate the distribution of oxygen concentration by combining it with the ideal gas equation, and replace the constant concentration term in the original equation for correction;

[0014] Step 7: Track the evolution of the Darcy velocity field on the material surface and modify the internal mechanical erosion equation;

[0015] Step 8: Set boundary conditions and initial values;

[0016] Step 9: Based on the rate equations derived and calculated above, set the mesh movement conditions and movement rates, and analyze the evolution of each erosion contribution during the ablation process through finite element iterative calculations.

[0017] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for simulating laser ablation of fully woven CFRP under tangential airflow when executing the computer program.

[0018] Compared with the existing technology, the present invention has the following significant advantages: It proposes a model for the external mechanical erosion of the dense structure of woven CFRP materials under high-speed tangential airflow and high-power laser density, and based on this model, derives the anisotropic thermal conductivity of the fully woven CFRP material. It also considers the influence of the vortex evolution in the ablation pit on oxygen mass transfer and external mechanical erosion, and corrects the internal mechanical erosion effect by combining the evolution of the Darcy velocity field on the material surface. The internal energy conservation equation is further corrected by considering the work done by the pyrolysis gas pressure change and viscous dissipation. By establishing a fluid-solid coupling model, this simulation method simultaneously analyzes the resin pyrolysis reaction, the oxidation and sublimation erosion of carbon fibers and residual carbon, the mechanical erosion caused by the external tangential airflow, and the mechanical erosion caused by the internal pyrolysis gas during laser ablation of carbon fiber-reinforced epoxy resin composites. This solves the problem of analyzing the different erosion contributions of carbon fiber-reinforced epoxy resin composites at different stages of laser ablation. This numerical simulation can reproduce the CFRP ablation process of any form of laser within a certain flow rate range, providing a theoretical and simulation basis for high-power laser damage to composite materials under high-velocity tangential airflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the two-dimensional modeling of the simulation method of laser ablation of fully woven CFRP materials under tangential airflow.

[0020] Figure 2 It is a schematic diagram of the physical model of dense structure.

[0021] Figure 3 Schematic diagram of the temperature and velocity distribution of irregular eddy currents in the ablation crater.

[0022] Figure 4 is the Darcy velocity evolution curve at the center point of the material.

[0023] Figure 5 It is a schematic diagram of mesh division.

[0024] Figure 6 is the contribution evolution curve of different erosion. DETAILED DESCRIPTION

[0025] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is described in further detail below with reference to embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0026] This paper provides a simulation method for laser ablation of fully woven CFRP materials under tangential airflow. During the numerical modeling process, an external mechanical erosion model of the dense structure of woven CFRP materials under high-speed tangential airflow and high-power laser density was introduced. Based on this model, the anisotropic thermal conductivity of the fully woven CFRP materials was derived. The method fully considers the influence of vortex evolution in the ablation crater on oxygen mass transfer and external mechanical erosion. The internal mechanical erosion effect is corrected by combining the evolution of the Darcy velocity field on the material surface. Furthermore, the internal energy conservation equation is modified to account for work done by pyrolysis gas pressure changes and viscous dissipation, thereby improving the computational accuracy of the fluid-structure interaction model.

[0027] The schematic diagram of the two-dimensional numerical model of the present invention is as follows Figure 1 As shown. On the basis of ensuring the reliability of the numerical calculation results, the following assumptions and simplifications are made to the model:

[0028] (1) Assume that pyrolysis, oxidation, and sublimation do not affect the gas composition in the fluid domain;

[0029] (2) Ignoring the complex chemical reactions between pyrolysis gases and materials;

[0030] (3) Ignore the thermal expansion and contraction effects of materials;

[0031] (4) Ignoring the redistribution of the flow field caused by irregular ablation and extraction of materials;

[0032] The specific steps of this method are as follows:

[0033] Step 1: Use the volume averaging method to homogenize the density, constant pressure heat capacity, and thermal conductivity of the material.

[0034] V i =m i / ρ i i=f,p,ch,g

[0035]

[0036]

[0037]

[0038]

[0039] In the above formula, the density of each component is assumed to be constant, and f, p, ch, and g correspond to carbon fiber, resin, residual carbon, and pyrolysis gas, respectively. represents the volume fraction of each component, ρ i Indicates the constant density of each component, c pi represents the constant-pressure heat capacity of each group, and ξ is the mass fraction of pyrolysis gas.

[0040] Step 2: Establish the governing equations based on the conservation of momentum, mass, and energy, and use the moving mesh method to track the interface recession and ablation process.

[0041] The fluid domain calculation uses the compressible fluid-conservation form Navier-Stokes equations:

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048] In the above formula, ρ air is the air density, is the air velocity vector, p air is the air pressure, μ air is the kinematic viscosity of air, F is the force source term, c P,air is the constant pressure heat capacity of air, λ air is the thermal conductivity of air, I is the unit matrix tensor, Q vd is the viscous dissipation term, Q p is the pressure work term, is the Hamiltonian operator.

[0049] The basic governing equations for the porous media domain combine the modified Fourier equations, the single-step Arrhenius equations, the single-phase Darcy law formula, and the Connier-Karman permeability model theory. They are specifically described as follows:

[0050]

[0051]

[0052]

[0053]

[0054]

[0055] In the above formula, ρ eff is the overall equivalent density of the material, c p,eff is the overall equivalent specific heat capacity of the material, is the Hamiltonian operator, L P is the latent heat of pyrolysis, ρ g , ρ p are the densities of pyrolysis gas and resin, are the porosity and resin volume fraction, is the Darcy velocity vector of the pyrolysis gas, is the pre-exponential factor of the pyrolysis reaction, E p is the activation energy of the pyrolysis reaction, is the volume fraction of the reaction terminal resin, is the initial resin volume fraction, κ is the permeability, p g is the Darcy pressure caused by pyrolysis gas, μ g is the dynamic viscosity of pyrolysis gas, d particle is the particle size of the porous medium, R is the universal gas constant, T is the matrix temperature, t is the calculation time, ξ is the mass fraction of the pyrolysis gas, and n is the reaction order.

[0056] Step 3: Construct a physical model of external mechanical erosion dense structure, such as Figure 2 As shown, the fluid velocity changes on the material surface in the ablation crater are tracked, mapped to the material surface through the boundary similarity principle, and the velocity term of the original equation is replaced for modification.

[0057] Under the action of high-power laser irradiation and high-speed tangential airflow, the mechanical erosion of carbon fiber is more severe. On the one hand, the high temperature quickly reduces the strength of carbon fiber. On the other hand, the rapid pyrolysis of resin and the slow pyrolysis at lower power can better maintain the dense structure of the material. Therefore, based on the above facts, the present invention constructs an external mechanical erosion dense structure physical model.

[0058] In fluid-structure interaction models, a velocity domain exists on the material surface, so theoretically, the flow velocity close to the material surface should be zero. However, this is not the case. The irregular ablation morphology on the material surface can disrupt the ideal velocity domain. Therefore, to characterize the mechanical erosion effect of tangential airflow on the material, the fluid velocity at a certain distance above the material surface is tracked. Using the boundary similarity mapping principle, the changing velocity field in the irregular ablation crater can be accurately tracked. This in turn corrects the mechanical erosion rate, thereby more accurately calculating the contribution of mechanical erosion.

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069] In the above formula, v out is the external mechanical equivalent erosion rate, D p is the external mechanical erosion rate of the resin matrix, D u is the mechanical erosion rate of the outer radial carbon fiber, D f is the mechanical erosion rate of the axial carbon fiber, δ is the ratio of the thickness of the fiber layer to the resin layer, ρ f , ρ p is a constant density of carbon fiber and resin, is the pre-exponential factor of the gasification reaction of carbon fiber and resin, E Af 、E Ap is the activation energy of the gasification reaction of carbon fiber and resin, λ f ,λ p is the thermal conductivity of carbon fiber and resin, c f 、c p is the constant pressure heat capacity of carbon fiber resin, are the initial strength of carbon fiber in the axial and radial directions and the initial strength of the resin matrix, σ f , σ f⊥ , σ pTare the real-time strength of axial, radial and resin matrix, are the strength variation factors of carbon fiber and resin matrix, is the temperature-dependent variable for the modified intensity factor, are the real-time volume fractions of carbon fiber, resin, and residual carbon, respectively. is the initial volume fraction of the resin, T w is the real-time temperature of the material surface, T0 is the initial temperature of the material surface, t is the laser action time, R is the universal gas constant, P ∑ The pressure head on the material surface.

[0070] Track the changes in fluid velocity on the material surface within the ablation crater, such as Figure 1 As shown, the velocity term of the original equation is replaced by the velocity term to make corrections, where the material surface pressure head is described as follows using the material surface velocity correction:

[0071] P ∑ =ρ air (u airsurface (t)·cos(θ)) 2

[0072] where ρ air is the air density, u airsurface (t) is the airflow velocity on the material surface as the ablation crater evolves, and θ is the angle between the velocity normal and the horizontal plane.

[0073] Step 4: Based on the dense structure theory, deduce and set the anisotropic thermal conductivity of the material, which is described as:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] In the above formula, λ solid is the solid equivalent thermal conductivity, λ1, λ2 are the thermal conductivities in the material surface direction, and λ3 is the thermal conductivity in the material thickness direction; ch ,λ p ,λ fare the constant thermal conductivities of residual carbon, resin, and carbon fiber, respectively; are the real-time volume fractions of carbon fiber, residual carbon, and resin, respectively. is the initial volume fraction of carbon fiber, A * 、N1、N2、b * 、s b 、s p is an intermediate variable, and η is the ratio of the thermal conductivity of residual carbon to the thermal conductivity of the matrix.

[0083] Step 5: Consider the work done by the pressure change and viscous dissipation of the pyrolysis gas and add it to the energy conservation equation of the porous medium for correction.

[0084] The generation of pyrolysis gas will cause changes in the internal pressure of the material. At the same time, due to the pressure gradient between the interior and the boundary, the pyrolysis gas will continuously overflow to the boundary. The pressure is constantly changing during the escape of the pyrolysis gas, and there is viscosity between the pyrolysis gas and the pores. Therefore, considering the work done by pressure change and viscous dissipation can more accurately calculate the evolution law of the internal temperature of the material.

[0085]

[0086]

[0087]

[0088]

[0089] In the above formula, ρ eff To describe the equivalent density of porous media, c p,eff is the equivalent constant-pressure heat capacity, λ eff is the equivalent thermal conductivity matrix, ρ p is the constant density of the resin, is the real-time volume fraction of the resin, L P is the latent heat of resin pyrolysis, c pg is the constant-pressure heat capacity of the pyrolysis gas, ρ g is the pyrolysis gas density, is the Darcy velocity vector of the pyrolysis gas, p g is the pyrolysis gas pressure, Q vd ′ is the viscous dissipation caused by the pyrolysis gas flow, Q p ′ is the work term of the internal pyrolysis gas pressure change, T is the material temperature, t represents the calculation time, is the Hamiltonian operator.

[0090] Step 6: Track the evolution of fluid temperature and pressure near the material surface in the ablation crater, and calculate the distribution of oxygen concentration in combination with the ideal gas equation, and then replace the constant concentration term in the original equation for correction.

[0091] In the fluid-solid coupling model, as the ablation pit deepens, a heat flow from the downwind to the upwind area will form in the ablation pit, and as the inflow velocity increases, this vortex heat flow becomes increasingly unstable and develops in a disordered direction, such as Figure 3 As shown in the figure, a region of airflow with drastically fluctuating temperatures will occur within the ablation crater. The large and irregular evolution of the airflow temperature will lead to differences in the oxygen concentration distribution within the ablation crater. Combined with the changing pressure within the ablation crater, the evolution of the oxygen concentration distribution within the ablation crater can be calculated based on the ideal gas equation. This can then be used to modify the oxidation ablation rate equation, making the calculation results more accurate.

[0092]

[0093]

[0094] In the above formula, v oxi is the oxidation reaction rate, A oxi is the pre-exponential factor of the oxidation reaction, E oxi is the activation energy of the oxidation reaction, M i is the average molar mass of the surface material participating in the oxidation reaction, is the equivalent surface density participating in the oxidation reaction, p air,surface is the oxygen partial pressure near the ablation crater surface, T air,surface is the gas temperature near the ablation crater surface, T surface is the material surface temperature, ζ is the correction coefficient, and R is the universal gas constant.

[0095] Step 7: Track the evolution of the Darcy velocity field on the material surface and modify the internal mechanical erosion equation based on the distribution characteristics of the Darcy field on the material surface.

[0096] During the laser ablation process, the resin first undergoes pyrolysis at a relatively low temperature. Due to the extremely high temperature rise rate, a large amount of pyrolysis gas accumulates in a short period of time, causing the internal pressure near the surface of the material to increase rapidly. During this stage, according to experimental observations, the internal mechanical erosion effect is the most severe. As the resin pyrolysis is complete, no more pyrolysis gas accumulates and escapes from the surface. Therefore, the internal mechanical erosion effect gradually decreases and tends to be stable. Figure 4 Based on the above facts, the present invention tracks the evolution of the Darcy velocity field on the material surface and uses it to correct the internal mechanical erosion rate, which is expressed as:

[0097]

[0098]

[0099] In the above formula, v int is the internal mechanical erosion rate, is the pre-exponential factor of the resin pyrolysis reaction, λ p is the thermal conductivity of the resin, ρ p is the resin density, c p is the constant pressure heat capacity of the resin, K is the permeability, l0 is the pore size, σ pT is the resin strength, E P is the activation energy of resin pyrolysis reaction, R is the universal gas constant, T surface is the surface temperature of the material, σ compsite,T is the composite material strength, Φ is the correction term, χ is the correction coefficient, u is the Darcy velocity of the material surface, u max is the peak Darcy velocity constant on the material surface, and ω is a constant.

[0100] Step 8: Calculate the vaporization rate on the material surface based on the Hertz-Langmuir vaporization equation and the Clausius-Cappellon saturated vapor pressure equation.

[0101]

[0102]

[0103]

[0104] ΔH sub =M c L sub

[0105] In the above formula, v sub is the sublimation rate, m sub is the mass flux density of carbon dissipation, is the equivalent density of the material surface participating in gasification, P th is the saturated vapor pressure, β is the reverse diffusion coefficient, ΔH sub is the gasification enthalpy of carbon, M c is the molar mass of carbon, L sub is the latent heat of carbon vaporization, T sub is the gasification temperature of carbon, T surface is the surface temperature of the material, P0 is the standard atmospheric pressure, and R is the universal gas constant.

[0106] Step 9: Set boundary conditions and initial conditions.

[0107] Energy conservation at the fluid-solid boundary:

[0108]

[0109] In the above formula, λ eff is the overall equivalent thermal conductivity of the material, is the temperature gradient, α is the absorption coefficient of the material to the laser, I Laseis the power density distribution, ε is the radiation coefficient, σ is the Stefan-Boltzmann constant, T surface is the surface temperature of the material, T e is the ambient temperature, is the equivalent density of the material surface participating in oxidation and sublimation, L oxi is the latent heat of oxidation, L sub is the latent heat of sublimation, v oxi is the oxidation rate, v sub is the sublimation rate.

[0110] Fluid-solid heat transfer boundary conditions and initial conditions:

[0111] Upper boundary of the fluid domain:

[0112] At the entrance of the fluid domain:

[0113] At the outlet of the fluid domain:

[0114] On a solid drop boundary:

[0115] Initial condition: T priamry =273.15[K]

[0116] In the above formula is the normal vector perpendicular to the boundary, λ air is the thermal conductivity of air, is the temperature gradient, ρ air is the air density, is the inlet enthalpy difference, h aL is the natural convection heat transfer coefficient, T enviroment is the ambient temperature, and T is the material temperature.

[0117] Boundary conditions and initial conditions for fluid flow:

[0118] Set normal flow at the fluid domain entrance: u in =u air

[0119] Static pressure at the fluid domain outlet: P out =1[atm]

[0120] Symmetry is set on the upper boundary of the fluid domain:

[0121] The slip condition is set at the extended boundary below the fluid domain (as shown in the figure): u air =u in

[0122] The no-slip condition is set on the lower boundary of the solid: u air =0

[0123] In the above formula is the normal vector perpendicular to the boundary, u air is the incoming flow velocity, P out is the outlet pressure.

[0124] Darcy's law boundary conditions and initial conditions:

[0125] Porous media boundary setting outlet pressure: P boundary =1[atm]

[0126] Initial condition inside porous media: P priamry =1[atm]

[0127] In the above formula, P boundary is the boundary pressure, P priamry is the initial pressure inside the porous medium.

[0128] Initial conditions for the domain differential equations characterizing resin pyrolysis:

[0129] Initial conditions for the domain differential equations characterizing carbon fiber body ablation:

[0130] In the above formula is the initial volume fraction of the resin, is the initial volume fraction of carbon fiber.

[0131] Step 10: Divide the grid into quadrilaterals, such as Figure 5 As shown in the figure, the grid movement conditions and rates are set, and the evolution of each erosion contribution during the ablation process is analyzed through finite element iterative calculations, as shown in the figure. Figure 6 shown.

[0132] v total =v out +v int +v oxi +v sub

[0133] Figure 6The ablation rate evolution curve for the material center point shows a clear upward trend in both internal and external mechanical erosion rates during the initial ablation phase, consistent with the physical reality of surface expansion caused by pyrolysis gases. With the complete release of pyrolysis gases, internal mechanical erosion contributes little to the erosion after 2.5 seconds. As the groove depth increases, the fluid velocity near the wall gradually decreases, and after 2.3 seconds, it contributes little to the erosion. As the temperature rises, the oxidation rate on the material surface gradually increases to a stable value of approximately 0.2 mm / s. However, in the case model, since the temperature does not reach the carbon vaporization temperature, no significant vaporization erosion rate is shown in the figure. Throughout the ablation process, the overall ablation rate increases rapidly from 0 to 1.5 seconds, reaching a peak of 0.85 mm / s around 1.5 seconds. It then decreases until around 2.3 seconds, remaining essentially constant at approximately 0.23 mm / s, marking the material's steady-state ablation phase.

[0134] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A simulation method for laser ablation of fully woven CFRP under tangential airflow, characterized in that: The following steps are involved: Step 1: Use the volume averaging method to homogenize the density, constant pressure heat capacity, and thermal conductivity of the material; Step 2: Establish the basic governing equations for the fluid and porous media domains based on the conservation theorems of momentum, mass, and energy, and use the moving mesh method to track the interface regression and ablation processes. Step 3: Construct a dense structure physical model, track the changes in fluid velocity on the material surface within the ablation crater, map it to the material surface using the boundary similarity principle, and replace the velocity term in the original equation for correction; Step 4: Based on the theory of dense structure, deduce and set the anisotropic thermal conductivity of the material; Step 5: Consider the work done by the pressure change and viscous dissipation of the pyrolysis gas and add it to the porous media energy conservation equation for correction; Step 6: Track the evolution of the temperature and pressure of the fluid on the surface of the material in the ablation crater, and calculate the distribution of oxygen concentration by combining it with the ideal gas equation, and replace the constant concentration term in the original equation for correction; Step 7: Track the evolution of the Darcy velocity field on the material surface and modify the internal mechanical erosion equation; Step 8: Set boundary conditions and initial values; Step 9: Based on the rate equations derived and calculated above, set the mesh movement conditions and movement rates, and analyze the evolution of each erosion contribution during the ablation process through finite element iterative calculations.

2. The simulation method for laser ablation of fully woven CFRP under tangential airflow according to claim 1, characterized in that: In the second step, the fluid domain calculation uses the compressible fluid-conservation form Navier-Stokes equations: In the above formula, ρ air is the air density, is the air velocity vector, p air is the air pressure, μ air is the kinematic viscosity of air, F is the force source term, c P，air is the constant pressure heat capacity of air, λ air is the thermal conductivity of air, I is the unit matrix tensor, Q vd is the viscous dissipation term, Q p is the pressure work term, is the Hamiltonian operator.

3. The simulation method for laser ablation of fully woven CFRP under tangential airflow according to claim 2, characterized in that: In the second step, the basic governing equations of the porous media domain are a combination of the modified Fourier equation, the single-step Arrhenius equation, the single-phase Darcy law formula, and the Connier-Karman permeability model theory, and are specifically described as follows: In the above formula, ρ eff is the overall equivalent density of the material, c p，eff is the overall equivalent specific heat capacity of the material, L P is the latent heat of pyrolysis, ρ g , ρ p are the densities of pyrolysis gas and resin, are the porosity and resin volume fraction, is the Darcy velocity vector of the pyrolysis gas, is the pre-exponential factor of the pyrolysis reaction, E p is the activation energy of the pyrolysis reaction, is the volume fraction of the reaction terminal resin, is the initial resin volume fraction, κ is the permeability, p g is the Darcy pressure caused by pyrolysis gas, μ g is the dynamic viscosity of pyrolysis gas, d particle is the particle size of the porous medium, R is the universal gas constant, T is the matrix temperature, t is the calculation time, ξ is the mass fraction of the pyrolysis gas, and n is the reaction order.

4. The simulation method for laser ablation of fully woven CFRP under tangential airflow according to claim 3, characterized in that: In the third step, a dense structural mechanics erosion model is constructed, which is described as: In the above formula, v out is the external mechanical equivalent erosion rate, D p is the external mechanical erosion rate of the resin matrix, D u is the mechanical erosion rate of the outer radial carbon fiber, D f is the mechanical erosion rate of the axial carbon fiber, δ is the ratio of the thickness of the fiber layer to the resin layer, ρ f , ρ p is a constant density of carbon fiber and resin, is the pre-exponential factor of the gasification reaction of carbon fiber and resin, E Af 、E Ap is the activation energy of the gasification reaction of carbon fiber and resin, λ f ,λ p is the thermal conductivity of carbon fiber and resin, c f 、c p is the constant pressure heat capacity of carbon fiber resin, are the initial strength of carbon fiber in the axial and radial directions and the initial strength of the resin matrix, σ f , σ f⊥ , σ pT are the real-time strength of axial, radial and resin matrix, are the strength variation factors of carbon fiber and resin matrix, is the temperature-dependent variable for the modified intensity factor, are the real-time volume fractions of carbon fiber, resin, and residual carbon, respectively. is the initial volume fraction of the resin, T w is the real-time temperature of the material surface, T0 is the initial temperature of the material surface, t is the laser action time, P ∑ The indenter is the material surface; Considering the change of fluid velocity on the material surface in the ablation crater, the velocity term of the original equation is replaced and corrected. The material surface pressure head is described by the material surface velocity correction as follows: P ∑ =ρ air (u airsurface (t)·cos(θ)) 2 Among them, u airsurface (t) is the airflow velocity on the material surface as the ablation crater evolves, and θ is the angle between the velocity normal and the horizontal plane.

5. The simulation method for laser ablation of fully woven CFRP under tangential airflow according to claim 4, characterized in that: The fourth step is to derive the anisotropic thermal conductivity of the solid phase of the fully woven composite material based on the dense structure, which is described as: In the above formula, λ solid is the solid equivalent thermal conductivity, λ1 and λ2 are the thermal conductivity in the material surface direction, and λ3 is the thermal conductivity in the material thickness direction; ch is the constant thermal conductivity of residual carbon; is the real-time volume fraction of residual carbon, is the initial volume fraction of carbon fiber, A * 、N1、N2、b * 、s b 、s p is an intermediate variable, and η is the ratio of the thermal conductivity of residual carbon to the thermal conductivity of the matrix.

6. The simulation method for laser ablation of fully woven CFRP under tangential airflow according to claim 5, characterized in that: In the fifth step, the viscous dissipation of the pyrolysis gas and the work done by the pressure change are considered and added to the energy conservation equation of the solid porous medium for correction, which is described as: In the above formula, λ eff is the equivalent thermal conductivity matrix, c pg is the constant-pressure heat capacity of the pyrolysis gas, Q vd ′ is the viscous dissipation caused by the pyrolysis gas flow, Q p ′ is the work term of the internal pyrolysis gas pressure change, T is the material temperature, and t represents the calculation time.

7. The simulation method for laser ablation of fully braided CFRP under tangential airflow according to claim 6, characterized in that: The sixth step is to consider the evolution of temperature and pressure of the fluid on the surface of the material in the ablation crater, simplify the chemical reaction on the material surface, assume sufficient oxygen, and only consider the carbon oxidation reaction. Combined with the ideal gas equation, the real-time distribution of oxygen concentration is calculated and the concentration term of the original equation is replaced to make corrections, which can be described as: In the above formula, v oxi is the oxidation reaction rate, A oxi is the pre-exponential factor of the oxidation reaction, E oxi is the activation energy of the oxidation reaction, M i is the average molar mass of the surface material participating in the oxidation reaction, is the equivalent surface density participating in the oxidation reaction, p air，surface is the oxygen partial pressure near the ablation crater surface, T air，surface is the gas temperature near the ablation crater surface, T surface is the surface temperature of the material, and ζ is the correction coefficient.

8. The simulation method for laser ablation of fully braided CFRP under tangential airflow according to claim 7, characterized in that: In the seventh step, the internal mechanical erosion equation is modified by considering the Darcy velocity field evolution on the material surface, which is described as: In the above formula, v int is the internal mechanical erosion rate, is the pre-exponential factor of the resin pyrolysis reaction, c p is the constant pressure heat capacity of the resin, K is the permeability, l0 is the pore size, σ pT is the resin strength, E P is the activation energy of resin pyrolysis reaction, T surface is the surface temperature of the material, σ compsite，T is the composite material strength, Φ is the correction term, χ is the correction coefficient, u is the Darcy velocity of the material surface, u max is the peak Darcy velocity constant on the material surface, and ω is a constant.

9. The simulation method for laser ablation of a fully woven carbon fiber reinforced epoxy resin composite material under tangential airflow according to claim 8, characterized in that: In the eighth step, the energy conservation of the fluid-solid interface is described as: In the above formula, λ eff is the overall equivalent thermal conductivity of the material, is the temperature gradient, α is the absorption coefficient of the material to the laser, I Laser is the power density distribution, ε is the radiation coefficient, σ is the Stefan-Boltzmann constant, T surface is the surface temperature of the material, T e is the ambient temperature, is the equivalent density of the material surface participating in oxidation and sublimation, L oxi is the latent heat of oxidation, L sub is the latent heat of sublimation, v oxi is the oxidation rate, v sub is the sublimation rate.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 9 are implemented.

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