Method for analyzing superhigh-speed impact damage of porous heat-resistant material

Abstract

The application relates to a kind of porous heat-resistant material ultra-high speed impact damage analysis method, belong to reusable spacecraft heat protection field.First, set initial material parameter, establish porous heat-resistant material model based on discrete element method, according to the density of simulated porous material and material component, the number of various types of particle microelement in the calculation domain of given size is calculated, and the particle of specified number and parameter is generated in random position and direction in the calculation domain.Fiber particle microelement or other irregular particle microelement in the skeleton model of porous material is replaced by the combination of spherical particles, the first connecting key is used between spherical particles, sintering between fiber particle microelement is simulated by the second connecting key, the porous heat-resistant material model is generated, space debris impact porous heat-resistant material simulation calculation is carried out, and the mechanical property degradation law of porous heat-resistant material after being impacted by space debris at ultra-high speed is evaluated.The model established by the application has high precision and good calculation stability.

Description

Technical Field

[0001] This invention relates to a method for analyzing ultra-high-speed impact damage of porous heat-resistant materials, particularly a method for analyzing the damage of porous heat-resistant materials under the impact of ultra-high-speed space debris, which belongs to the field of thermal protection for reusable aircraft. Background Technology

[0002] With the development of space technology, reusable launch vehicle technology for round-trip flights between Earth and space has become a focal point of competition among major powers. Due to prolonged exposure to extreme environments of high heat flux and high enthalpy, reusable spacecraft face increasingly higher requirements for their thermal protection systems, including long-term non-ablation, efficient heat insulation, high reliability, and lightweight design. Looking at the development paths of foreign aerospace technologies, it is clear that thermal protection technology is one of the first technical challenges they have addressed.

[0003] As the outermost "barrier" of an aircraft, the thermal protection system protects the fuselage and internal structure from damage caused by aerodynamic heat and other loads. Its reliability has become a bottleneck restricting the development of reusable launch vehicle technology. For reusable aircraft to operate in orbit for extended periods, in addition to the impact risks from accidental falling debris during launch and reentry, the greater threat comes from space debris. In recent years, due to increasingly frequent human space activities, the amount of space debris has increased rapidly. Impacts from space debris on aircraft are unavoidable, requiring thermal protection materials to possess certain impact resistance properties, and ensuring that damage to the thermal protection material after impact does not affect its thermal protection and load-bearing capacity.

[0004] Porous thermal protection materials, such as quartz fiber composite rigid thermal insulation tiles and porous ceramics, possess advantages such as high temperature resistance, low density, and good high-temperature mechanical properties, making them widely used in thermal protection systems for reusable aircraft. During long-term on-orbit missions, these porous thermal protection materials are exposed on the aircraft surface and inevitably subjected to impacts from space debris. Damage and failure analysis of porous thermal protection materials under the ultra-high-speed impact of space debris requires the establishment of a multi-scale constitutive model for these materials. Based on this model, a method for predicting the impact damage mechanical properties can be developed to accurately predict the nonlinear damage process of materials under ultra-high-speed impacts, providing a foundation for the application of porous thermal protection materials in the thermal protection of reusable aircraft.

[0005] While there are relatively mature research results on metal-based impact protection materials, studies on the damage of porous heat-resistant materials prepared from non-metallic materials under ultra-high-speed impact are limited. Furthermore, existing finite element methods or meshless methods (such as the smoothed particle flow method) still have some shortcomings in handling this problem. Firstly, they struggle to describe discontinuous media with high porosity, relying solely on macroscopic phenomenological constitutive models, which may differ significantly from reality. Secondly, high strain rates can lead to finite element mesh distortion when dealing with ultra-high-speed impact problems, and the computational stability of meshless methods depends on the selection of the kernel function. Therefore, a damage analysis method suitable for ultra-high-speed impact of porous heat-resistant materials is needed. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the drawbacks of existing methods that rely on traditional design approaches, and to provide a method for analyzing ultra-high-speed impact damage in porous heat-resistant materials.

[0007] The technical solution of this invention is:

[0008] A method for analyzing ultra-high-speed impact damage of porous heat-resistant materials includes:

[0009] Set the initial material parameters, including the elastic modulus, Poisson's ratio, and density of each component material;

[0010] The porous heat-resistant material is composed of particulate micro-elements, including spherical particulate micro-elements, short fiber particulate micro-elements, or other irregular particulate micro-elements. The parameters of these particulate micro-elements, including diameter d, fiber length l, and particle size distribution Ψ, are obtained by scanning the porous heat-resistant material with an electron microscope. d (d) Length distribution Ψ l (l);

[0011] The number of various particle micro-elements in a given-size computational domain is calculated based on the density and composition of the simulated porous heat-resistant material. Particle micro-elements of the specified number and parameters are generated in the computational domain at random positions and orientations. The porous material skeleton model formed by the accumulation of particle micro-elements is adjusted to make its porosity consistent with that of the simulated porous heat-resistant material.

[0012] The fibrous particle micro-elements or other irregular particle micro-elements in the porous material skeleton model are replaced with a combination of spherical particle micro-elements. The spherical particle micro-elements are connected by a first connecting bond. The normal stiffness, tangential stiffness, tensile strength, and shear strength of the first connecting bond are consistent with the material mechanical properties of each component.

[0013] The second bonding bond is used to simulate the sintering between fiber particle micro-elements;

[0014] A porous heat-resistant material model is generated. Based on the probability distribution of particle size, velocity, and impact angle of space debris particles, space debris particles are generated. The space debris particles are simulated using spherical or irregular particles. The simulation step size Δt is adjusted to stabilize the calculation. Simulation calculation of space debris impacting the porous heat-resistant material is carried out.

[0015] The state of the bonds between micro-elements and the interaction forces between micro-elements, as well as the velocity of micro-elements, are extracted from the simulation results. The stress cloud map, damage evolution, and propagation and energy dissipation laws of shock waves inside micro-elements are obtained by using the coarsening method.

[0016] Based on simulation calculations, the changes in the force chain network before and after the space debris impact are obtained, the damage impact range of the space debris impact is determined, and for porous heat-resistant materials damaged by impact, uniaxial tensile test, direct shear test and three-point bending test simulation calculations are carried out to evaluate the degradation law of the mechanical properties of porous heat-resistant materials after ultra-high speed impact of space debris.

[0017] Preferably, the second bonding parameters between the fiber particle micro-elements need to be corrected based on actual mechanical property data. The correction method is to conduct uniaxial tensile tests, direct shear tests, and three-point bending tests on the generated porous heat-resistant material, compare the stress-strain curves of the simulation and the test, and iteratively calculate until the stress-strain curves of the simulation and the test are consistent. At this time, the second bonding parameters between the fiber particle micro-elements corresponding to the simulation are the micro-scale parameters that are consistent with the macroscopic mechanics of the porous heat-resistant material. The porous heat-resistant material model is generated based on the micro-scale parameters.

[0018] Preferably, the formation process of the porous material framework model is as follows:

[0019] (1) In a given size computational domain, set up a container according to the geometric shape of the porous heat-resistant material, and calculate the mass of various particle micro-elements in the given size container according to the density and material composition of the simulated porous heat-resistant material.

[0020] (2) Establish contact force models between micro-particles and between micro-particles and the container. The contact force model decomposes the contact force between micro-particles into normal and tangential contact forces F. n F t and normal and tangential damping forces F n d F t d The specific form is expressed as follows:

[0021]

[0022] In the formula, E * It is the equivalent elastic modulus, satisfying E i Ej Let v be the elastic modulus of particle element i,j. i ,v j Let be the Poisson's ratio of particles i and j;

[0023] R * It is the equivalent radius, satisfying R i ,R j Let be the radius of particle element i,j;

[0024] 'a' is the contact radius, which satisfies... x i ,x j Let be the centroid displacement vector of particle element i,j;

[0025]

[0026] In the formula, m * It is equivalent quality, satisfying m i ,m j Let i be the mass of the particle element i,j;

[0027] In the formula, the normal component of the relative velocity V i V j Let i be the velocity of particle element i,j, and let j be the normal vector of the contact surface. Normal stiffness Damping coefficient e ij Let be the collision recovery coefficient of particle element i,j;

[0028] F t =-S t δ

[0029] In the formula, δ is the tangential overlap. For tangential stiffness, G * It is the equivalent shear modulus, which satisfies G i G j Let i be the shear modulus of particle element i,j;

[0030]

[0031] In the formula, It is the tangential component of the relative velocity;

[0032] (3) Temporarily reduce the friction coefficient μ between the micro-particles. ij Set the pressure to 0, apply a constant pressure to the particle stack for triaxial compression, gradually increasing the pressure until the particle element stabilizes, i.e., the particle element velocity is less than 10. -3m / s, calculate the porosity of the particle pack after stabilization;

[0033] (4) When the porosity of the particle stack is consistent with that of the target porous heat-resistant material, maintain the pressure and reduce the friction coefficient μ between the particle micro-elements. ij Adjust to the actual measured value, set the coefficient of restitution e = 0.001, and rapidly stabilize the particle pile until the velocity of the particle element is less than 10. -4 m / s.

[0034] Preferably, the first linker satisfies:

[0035] Normal force

[0036] Tangential force

[0037] normal torque

[0038] Tangential torque

[0039] In the formula These are the normal stiffness and tangential stiffness, respectively, and their initial values ​​are as follows: Given, u n u t θ represents normal deformation and tangential deformation, respectively. n θ t These represent the changes in the normal and tangential direction angles, respectively. A = πR B 2 R B R is the radius of the first bonding bond. B =R i .

[0040] Preferably, when the displacement of the centroid of the particle element is greater than the sum of the radii of the particle element, the shear force of the first bonding bond is... The tensile force of the first connecting key is

[0041] When the shear or tensile force exceeds the threshold, the fiber breaks.

[0042] Preferably, the radius of the second linker

[0043] Preferably, the normal stiffness and tangential stiffness of the second connecting key satisfy Where E porous G porous These are the elastic modulus and shear modulus of the porous heat-insulating material.

[0044] Preferably, the method for obtaining the internal stress of a particle micro-element using a coarsening method is as follows:

[0045] In a solution domain containing N infinitesimal particles, the velocity v(x) and stress σ(x) at any point x are determined by a radius R from that point. w The velocities of the infinitesimal particles within the space and the contact forces between the infinitesimal particles are calculated as follows:

[0046]

[0047] Where m α It is the mass of the particle element α, x α v α α is the position vector and velocity vector of the center of mass of the particle element α, and W is the weighting function;

[0048]

[0049] Where xα β =xα-x β It is the position vector from the center of mass of particle α to particle β, v'α(x) = vα - v(x) is the velocity fluctuation of particle α, and f αβ Let be the contact force between particle element α and particle element β.

[0050] Preferred weight function

[0051]

[0052] in It is a radius of R w The volume of the spherical region, where γ is a variable.

[0053] The advantages of this invention compared to the prior art are:

[0054] (1) This invention establishes a microstructural description of porous heat-resistant materials based on microscopic features such as fiber skeleton and pores. Compared with the commonly used finite element method and meshless method, this invention starts only from the microscopic contact model and assumes fewer constitutive models that do not rely on macroscopic phenomenology, which can achieve an accurate description of discontinuous media such as porous heat-resistant materials.

[0055] (2) This invention achieves the correction of macroscopic mechanical properties to microscopic models through performance testing and simulation, and establishes the relationship between microscopic parameters of particles with practical physical significance and macroscopic mechanical properties of porous heat-resistant materials.

[0056] (3) The calculation method of the present invention is stable and avoids the mesh distortion problem caused by high strain rate when the finite element method is dealing with ultra-high speed impact. It also does not need to consider the influence of kernel function on calculation stability as in the meshless method. Attached Figure Description

[0057] Figure 1 Histogram of fiber aspect ratio distribution (log-normal distribution);

[0058] Figure 2 Schematic diagram of non-spherical particles;

[0059] Figure 3 Porous fiber skeleton;

[0060] Figure 4 Particle contact force model;

[0061] Figure 5 Flowchart for analysis of ultra-high speed impact damage in porous heat-resistant materials; Detailed Implementation

[0062] The invention will now be further described with reference to the accompanying drawings.

[0063] This invention provides a method for dynamic simulation and damage analysis of porous thermal protection materials under ultra-high-speed impact. During their on-orbit service, porous thermal protection materials have a certain probability of being subjected to ultra-high-speed impacts from space debris, causing damage. Upon reentry, the already damaged porous thermal protection materials will still be subjected to complex forces, thermal loads, vibrations, and noise. To assess the reliability of thermal protection systems composed of porous thermal protection materials, it is necessary to accurately predict the nonlinear damage process of the material under ultra-high-speed impacts from space debris. This invention establishes a set of impact damage analysis methods and procedures considering the microstructural characteristics and macroscopic mechanical properties of porous thermal protection materials. This method can be applied to the ultra-high-speed impact damage analysis of porous thermal protection materials with different processes and material compositions.

[0064] The steps of this invention are as follows:

[0065] 1) Set initial material parameters, including the elastic modulus, Poisson's ratio, and density of each component material;

[0066] 2) A porous heat-resistant material model was established based on the discrete element method. The porous heat-resistant material model is composed of particle micro-elements, including spherical particle micro-elements, short fiber particle micro-elements, or other irregular particle micro-elements. The diameter d, fiber length l, and particle size and length distribution Ψ required for modeling were obtained through electron microscopy scanning results. d (d), Ψ l (l).

[0067] 3) Calculate the number of various particle elements in a given-size computational domain based on the density and composition of the simulated porous material. Generate a specified number of particles with specified parameters at random positions and orientations within the computational domain. Adjust the porous material framework formed by particle packing to make its porosity consistent with the simulated porous material.

[0068] 4) Considering the potential for fiber failure, the fiber particles or other irregular particle elements in the porous material skeleton model are replaced with a combination of spherical particles. The spherical particles are connected by a first bonding bond, and the normal stiffness, tangential stiffness, tensile strength, and shear strength of the first bonding bond are consistent with the mechanical properties of each component.

[0069] 5) The sintering between fiber particles is simulated using a second bonding mechanism. The parameters of this second bonding mechanism need to be corrected based on actual mechanical property data. Simulations of uniaxial tensile testing, direct shear testing, and three-point bending testing are performed on the generated porous material. The stress-strain curves from the simulation and experiments are compared and iteratively calculated until the simulation and experimental stress-strain curves are consistent. At this point, the parameters of the second bonding mechanism match the macroscopic mechanical properties of the porous material.

[0070] 6) Generate a porous heat-resistant material model based on the corrected mesoscopic parameters. Generate space debris particles according to the probability distribution of particle size, velocity, and impact angle. These particles can be simulated as spherical or irregular particles. Adjust the simulation step size Δt to stabilize the calculation and conduct simulation calculations of space debris impacting the porous heat-resistant material.

[0071] 7) Extract the state of interparticle bonds and the time-varying interparticle interaction forces, as well as the time-varying particle velocity. Use coarsening methods to obtain stress cloud maps, damage evolution, shock wave propagation, and energy dissipation patterns within the particles.

[0072] 8) Based on simulation calculations, the changes in the force chain network before and after the space debris impact are obtained, the damage impact range of the space debris impact is determined, and for porous heat-resistant materials damaged by impact, simulation calculations of uniaxial tensile test, direct shear test and three-point bending test are carried out to evaluate the degradation law of the mechanical properties of porous heat-resistant materials after being subjected to ultra-high speed impact of space debris.

[0073] Example:

[0074] The method of the present invention will be illustrated by taking fiber-reinforced porous ceramics as an example.

[0075] 1) Input the performance parameters of each material according to the composition of the fiber-reinforced porous ceramic, including elastic modulus, Poisson's ratio, and density; also consider the interaction between particles (including particles of the same material and particles of different materials), and set the friction coefficient, collision recovery coefficient, and rolling friction. The friction coefficient can be obtained through experiments such as the angle of repose test of fiber materials; the collision recovery coefficient can be calibrated according to subsequent simulation results, and the initial value is set to 0.9. Rolling friction characterizes the ability of the particle contact interface to resist rotation. It is a parameter related to particle shape. In the simulation, non-spherical particles are used directly and the sintering between particles is considered. Rotation is not likely to occur, so this effect can be ignored and set to 0.01.

[0076] 2) Obtain the distribution of fiber diameter d, fiber length l, and aspect ratio Ψ required for modeling based on the electron microscopy scanning results of each component material. l (l). For example Figure 1 As shown, ignoring minute variations in fiber diameter, the fiber length distribution approximates a log-normal distribution. First, spherical particles for each component material are established, with diameters matching the fiber diameters. Then, a multi-spherical approximation method is used to generate… Figure 2 The short fiber model (or other non-spherical particles) shown has a fiber aspect ratio distribution that follows Ψ. l (l).

[0077] 3) Set up a container based on the geometry of the target porous material, and calculate the mass of various particle elements in the container of a given size based on the density and composition of the simulated porous material. Set the initial gravitational acceleration to 0, and generate particles of a specified mass at random positions and directions within the designated area. At this point, the generated fiber particles are not yet in contact, and the porosity is too high. The porosity of the particle stack needs to be adjusted to match that of the target porous fiber skeleton, such as... Figure 3 The specific measures are as follows:

[0078] A contact force model is established between particles and between particles and the container, decomposing the contact force between particles into normal and tangential contact forces F. n F t and normal and tangential damping forces F n d F t d The specific form is expressed as follows:

[0079] Normal contact force

[0080] In the formula, E * It is the equivalent elastic modulus, satisfying E i E j Let v be the elastic modulus of particles i and j. i ,v j Let be the Poisson's ratio of particles i and j.

[0081] In the formula, R * It is the equivalent radius, satisfying R i ,R j Where is the particle radius.

[0082] In the formula, 'a' is the contact radius, which satisfies... x i ,x j This is the displacement vector of the particle's center of mass.

[0083]

[0084] In the formula, m * It is equivalent quality, satisfying m i ,m j This refers to particle mass.

[0085] In the formula, the normal component of the relative velocity V i V j The particle velocity. The normal vector of the contact surface. Normal stiffness Damping coefficient e ij Let be the collision recovery coefficient of particle element i,j;

[0086] F t =-S t δ (3)

[0087] In the formula, δ is the tangential overlap. G represents the tangential stiffness. * It is the equivalent shear modulus, which satisfies G i G j Let be the shear modulus of particles i and j.

[0088]

[0089] In the formula, It is the tangential component of the relative velocity.

[0090] In this step, the friction coefficient μ between particles is temporarily set. ij Set to 0, apply a constant pressure (σ) to the particle stack. x =σ y =σ z =p) Perform triaxial compression, gradually increasing the pressure, with each stage loading until the particles stabilize, i.e., the particle velocity is less than 10. -3 m / s. Calculate the porosity of the particle pack after stabilization. The porous heat-insulating material contains n components, ∑m i′ V is the mass of the i′ component particle. b It is the outer envelope volume of the particle stack, ρ i' Let be the density of the i′ component particles.

[0091] c. Maintain pressure when the porosity of the particle pack matches that of the target porous material. The friction coefficient μ between particles... ij Adjust the values ​​to the actual measured values, and set the interparticle restitution coefficients to 0.001 to quickly stabilize the particle pile until the particle velocity is less than 1. 0-4 m / s.

[0092] 4) Considering the potential damage to the fibers themselves, replace the fiber particles or other irregular particle elements in the porous material skeleton model with a combination of spherical particles. This particle replacement differs from the multi-spherical approximation in step (2). There is no overlap between the spherical particles; they are connected by a first bonding bond. The function of the first bonding bond is as follows: Figure 4 As shown, it can be expressed in the following form:

[0093] Normal force

[0094] Tangential force

[0095] normal torque

[0096] Tangential torque

[0097] In the formula These are the normal stiffness and tangential stiffness, respectively, and their initial values ​​are as follows: The result is given and corrected through simulation and experimental calibration. n u t θ represents normal deformation and tangential deformation, respectively. n θ t These represent the changes in the normal and tangential direction angles, respectively.

[0098] In the formula A = πR B 2 R B Let R be the radius of the first bond, which can be set to be the same as the particle radius. B =R i .

[0099] When the tensile or shear force exceeds the threshold, the first bond breaks.

[0100]

[0101] Where σ max τ max The tensile strength and shear strength of the fiber are given respectively, which are the threshold values ​​for tensile force and shear force.

[0102] After the first bond breaks, the interaction between particles is calculated according to the contact force model in step (3).

[0103] 5) In porous heat-resistant materials, fibers are bonded together by sintering to form a porous fiber skeleton. In the discrete element model, the sintering between fiber particles is represented by a second bonding bond. Its expression is the same as the first bonding bond in step (4), but the parameter values ​​of the second bonding bond need to take into account the sintering effect. The radius R of the second bonding bond is... B 'satisfy:

[0104]

[0105] Normal stiffness and tangential stiffness in the second connecting key You can press first Given, where E porous G porous For porous materials, these are the elastic modulus and shear modulus. Bond fracture strength σ0 max * τ max * The initial values ​​can be given based on the tensile and shear strengths of the porous material. However, parameter calibration is still required based on the comparison between uniaxial tensile and three-point bending test results and simulations. The prepared simulated specimen is subjected to a constant rate. ( (where H is the strain rate and H is the specimen height) The specimen is stretched until it breaks in the simulation. The value must be small enough (satisfying) P is the applied pressure, ensuring the system is in a quasi-static state. The second bonding parameters are adjusted so that the slope and peak value of the linear segment of the simulated strain-stress curve match the experimental results. Parameters calibrated using experimental results can be used as input for subsequent simulations.

[0106] A porous heat-resistant material model is generated based on the corrected microscopic parameters. Space debris particles are generated based on the particle size, velocity, and impact angle probability distribution of the space debris particles. For space particles with high strength and small particle size, a single spherical particle can be used for simulation. For particles with larger particle size, the method in step (4) can be used to simulate multiple spherical particles aggregated into arbitrary irregular shapes. The size of the contact search domain during simulation is set to 2.5 times the fiber radius. The simulation step size Δt needs to be adjusted to stabilize the calculation. Generally, the simulation step size Δt is set to 20% of the Rayleigh wave step size (i.e., the time required for the Rayleigh wave to travel through the hemisphere). v i Let ρ be the Poisson's ratio of the particulate micro-element i material. i G represents the density of the particulate micro-element material i. i Let V be the shear modulus of the particle element i, and let V be the relative velocity between particles during ultra-high-speed impact. i,j Large, with the following additional constraint: Δt≤0.2min{R i} / max{V i,j The simulation step size is the smaller of the two values. In the simulation calculation, the interaction between particles after the first and second bonds break is calculated according to the contact force model in step (3).

[0107] 6) Extract the interaction forces between particle elements and the particle velocities at each moment in the simulation results. Use a coarsening method to obtain stress and velocity contour maps within the particles. Through the coarsening method, for a solution domain containing N particles, the velocity v(x) and stress σ(x) at any point within the domain can be calculated from the particle velocities and contact forces within a radius Rw from that point.

[0108]

[0109] Where m a It is particle mass, x a v a These are the position and velocity vectors of the particle's center of mass. W is the weighting function.

[0110]

[0111] Where x αβ =x α -x β It is the position vector from the center of mass of particle α to particle β. α (x)=v α -v(x) is the velocity fluctuation of particle α, f αβ Let be the contact force between particle element α and particle element β.

[0112] Using a sphere-Gauss weight function:

[0113]

[0114] in It is a radius of R w The volume of the spherical region.

[0115] 7) Based on simulation calculations, the changes in the force chain network before and after the space debris impact are obtained, the damage impact range of the space debris impact is determined, and for porous heat-resistant materials damaged by impact, uniaxial tensile tests, direct shear tests, and three-point bending tests are conducted to evaluate the degradation law of the mechanical properties of porous heat-resistant materials after ultra-high-speed impact of space debris. The overall analysis process is as follows: Figure 5 As shown. The constitutive model refers to the bonding model between particle elements.

[0116] The parts of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A method for analyzing ultra-high-speed impact damage of porous heat-resistant materials, characterized in that... include: Set the initial material parameters, including the elastic modulus, Poisson's ratio, and density of each component material; The porous heat-resistant material is composed of particulate micro-elements, including spherical particulate micro-elements, short fiber particulate micro-elements, or other irregular particulate micro-elements. The parameters of these particulate micro-elements, including diameter d, fiber length l, and particle size distribution Ψ, are obtained by scanning the porous heat-resistant material with an electron microscope. d (d) Length distribution Ψ l (l); The number of various particle micro-elements in a given-size computational domain is calculated based on the density and composition of the simulated porous heat-resistant material. Particle micro-elements of the specified number and parameters are generated in the computational domain at random positions and orientations. The porous material skeleton model formed by the accumulation of particle micro-elements is adjusted to make its porosity consistent with that of the simulated porous heat-resistant material. The fibrous particle micro-elements or other irregular particle micro-elements in the porous material skeleton model are replaced with a combination of spherical particle micro-elements. The spherical particle micro-elements are connected by a first connecting bond. The normal stiffness, tangential stiffness, tensile strength, and shear strength of the first connecting bond are consistent with the material mechanical properties of each component. The second bonding bond is used to simulate the sintering between fiber particle micro-elements; A porous heat-resistant material model is generated. Based on the probability distribution of particle size, velocity, and impact angle of space debris particles, space debris particles are generated. The space debris particles are simulated using spherical or irregular particles. The simulation step size Δt is adjusted to stabilize the calculation. Simulation calculation of space debris impacting the porous heat-resistant material is carried out. The state of the bonds between micro-elements and the interaction forces between micro-elements, as well as the velocity of micro-elements, are extracted from the simulation results. The stress cloud map, damage evolution, and propagation and energy dissipation of shock waves inside the micro-elements are obtained by using the coarsening method. Based on simulation calculations, the changes in the force chain network before and after the space debris impact are obtained, the damage impact range of the space debris impact is determined, and for porous heat-resistant materials damaged by impact, simulation calculations of uniaxial tensile test, direct shear test and three-point bend test are carried out to evaluate the degradation law of the mechanical properties of porous heat-resistant materials after being subjected to ultra-high speed impact of space debris. The formation process of the porous material framework model is as follows: (1) In a given size computational domain, set up a container according to the geometric shape of the porous heat-resistant material, and calculate the mass of various particle micro-elements in the given size container according to the density and material composition of the simulated porous heat-resistant material. (2) Establish contact force models between micro-particles and between micro-particles and the container. The contact force model decomposes the contact force between micro-particles into normal and tangential contact forces F. n F t and normal and tangential damping forces F n d F t d The specific form is expressed as follows: In the formula, E * It is the equivalent elastic modulus, satisfying E i E j Let v be the elastic modulus of particle element i,j. i ,v j Let be the Poisson's ratio of particles i and j; R * It is the equivalent radius, satisfying R i ,R j Let be the radius of particle element i,j; 'a' is the contact radius, which satisfies... x i ,x j Let be the centroid displacement vector of particle element i,j; In the formula, m * It is equivalent quality, satisfying m i ,m j Let i be the mass of the particle element i,j; In the formula, the normal component of the relative velocity V i V j Let i be the velocity of particle element i,j, and let j be the normal vector of the contact surface. Normal stiffness Damping coefficient e ij Let be the collision recovery coefficient of particle element i,j; F t =-S t d In the formula, δ is the tangential overlap. For tangential stiffness, G * It is the equivalent shear modulus, G i G j Let i be the shear modulus of particle element i,j; In the formula, It is the tangential component of the relative velocity; (3) Temporarily reduce the friction coefficient μ between the micro-particles. ij Set the pressure to 0, apply a constant pressure to the particle stack for triaxial compression, gradually increasing the pressure until the particle element stabilizes, i.e., the particle element velocity is less than 10. -3 m / s, calculate the porosity of the particle pack after stabilization; (4) When the porosity of the particle stack is consistent with that of the target porous heat-resistant material, maintain the pressure and reduce the friction coefficient μ between the particle micro-elements. ij Adjust to the actual measured value, set the coefficient of restitution e = 0.001, and rapidly stabilize the particle pile until the velocity of the particle element is less than 10. - 4 m / s; The method for obtaining the internal stress of a particle element using a coarsening approach is as follows: In a solution domain containing N infinitesimal particles, the velocity v(x) and stress σ(x) at any point x are determined by a radius R from that point. w The velocities of the infinitesimal particles within the space and the contact forces between the infinitesimal particles are calculated as follows: Where m α It is the mass of the particle element α, x α v α α is the position vector and velocity vector of the center of mass of the particle element α, and W is the weighting function; Where x αβ =x α -x β It is the position vector from the center of mass of particle element α to particle element β, v 'α (x)=v α -v(x) is the velocity fluctuation of particle α, f αβ Let be the contact force between particle element α and particle element β.

2. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 1, characterized in that, The second bonding parameters between the fiber particle micro-elements need to be corrected based on the actual mechanical property data. The correction method is to conduct uniaxial tensile tests, direct shear tests, and three-point bending tests on the generated porous heat-resistant material, compare the stress-strain curves of the simulation and the test, and iteratively calculate until the stress-strain curves of the simulation and the test are consistent. At this time, the second bonding parameters between the fiber particle micro-elements corresponding to the simulation are the micro-scale parameters that are consistent with the macroscopic mechanics of the porous heat-resistant material. The porous heat-resistant material model is generated based on the micro-scale parameters.

3. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 1, characterized in that, G * satisfy 4. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 3, characterized in that, The first join key satisfies: Normal force Tangential force normal torque Tangential torque In the formula These are the normal stiffness and tangential stiffness, respectively, and their initial values ​​are as follows: Given, u n u t θ represents normal deformation and tangential deformation, respectively. n θ t These represent the changes in the normal and tangential direction angles, respectively. A = πR B 2 R B R is the radius of the first bonding bond. B =R i .

5. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 4, characterized in that, When the displacement of the centroid of the particle element is greater than the sum of the radii of the particle element, the shear force of the first bonding bond is: The tensile force of the first connecting key is When the shear or tensile force exceeds the threshold, the fiber breaks.

6. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 4, characterized in that, Radius of the second bond 7. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 6, characterized in that, Normal and tangential stiffness of the second connecting key satisfy Where E porous G porous These are the elastic modulus and shear modulus of the porous heat-insulating material.

8. The method for analyzing ultra-high-speed impact damage of porous heat-resistant materials according to claim 1, characterized in that, weight function in It is a radius of R w The volume of the spherical region, where γ is a variable.

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