Mechanical property simulation method for simulating defects of carbon fiber composite material based on Monte Carlo-finite element

Abstract

The invention relates to the field of composite material prediction based on a specific model, and discloses a mechanical property simulation method for simulating defects of a carbon fiber composite material based on Monte Carlo-finite element, which comprises the following steps: constructing a carbon fiber composite material RVE model in Monte Carlo software, setting an irradiation physical reaction process, and carrying out neutron irradiation analogue simulation. The method comprises the following steps: obtaining internal void defect information of a material, constructing a finite element RVE model containing void defects in finite element software, obtaining an elastic constant matrix of the whole RVE model, constructing a macroscopic tensile finite element model, carrying out material parameter setting and simulation boundary condition setting on the macroscopic model, and carrying out macroscopic tensile simulation to obtain simulation mechanical data. According to the method, the problems of high cost and long time of an irradiation experiment and a mechanical experiment are solved, a technical basis is provided for reliability evaluation research of the carbon fiber composite material in a nuclear radiation scene, and a large amount of time and economic cost are saved.

Description

Technical Field

[0001] The present invention relates to the field of composite material prediction based on a specific model, and in particular to a method for simulating the mechanical properties of a carbon fiber composite material after irradiation damage, and specifically to a method for simulating the mechanical properties of a carbon fiber composite material due to neutron irradiation-induced defects and resulting in performance degradation based on a Monte Carlo-finite element model. Background Art

[0002] Carbon fiber composites are widely used in aerospace, construction, electronics and other fields due to their advantages such as light weight, high strength, corrosion resistance and design flexibility. However, when carbon fiber composites are used in aerospace structural parts, especially in radiation environments, spacecraft and satellites in space are exposed to high-energy particles and radiation beams, which will have a significant impact on the material structure and performance. Carbon fiber composites must be able to withstand these radiation environments to avoid material aging, mechanical performance degradation and even failure caused by radiation, so as to avoid serious impact on the reliability of carbon fiber composite structural parts. Neutron irradiation usually causes significant and complex damage effects: due to its electrical neutrality, neutron irradiation can penetrate matter more effectively and collide elastically and inelasticly with atomic nuclei. These collisions cause displacement damage to the atomic nuclei, which will produce vacancy defects in the matrix and carbon fiber parts of the carbon fiber composites, resulting in performance parameter degradation of the mechanical strength and modulus of the carbon fiber composite structural parts, reducing the strength, toughness and fatigue life of the material, and increasing the brittleness and fracture risk of the material. Therefore, in design and engineering applications, it is necessary to fully consider and take effective measures to reduce the impact of defects caused by radiation on the mechanical properties of the material. A lot of research has been done at home and abroad on the degradation of mechanical properties of carbon fiber composites caused by neutron irradiation, and corresponding irradiation experiments and mechanical experiments have been carried out. However, for different types of carbon fiber composites, there are large differences in the degree of irradiation damage and the influence of nuclear radiation on mechanical properties parameters of carbon fiber composites, which makes the cost of conducting corresponding irradiation and mechanical experimental research high. The theoretical simulation research on the mechanical properties of carbon fiber composites has the advantages of short time consumption, high accuracy, and low economic cost. It is used as an important method to study the degradation analysis of mechanical properties of carbon fiber composites induced by radiation damage.

[0003] At present, the traditional research on mechanical properties of carbon fiber materials irradiated with damage mainly relies on experimental methods, but this requires a lot of time and economic costs. Therefore, it is very necessary to develop a simulation method to simulate the damage caused by defects in carbon fiber composites after irradiation. Summary of the invention

[0004] Aiming at the problem that carbon fiber composite materials are easily degraded by neutron irradiation in a radiation environment and their mechanical properties are easily degraded, while irradiation experiments and mechanical experiments are costly and time-consuming, the present invention designs and develops a method for simulating the material damage and degradation of carbon fiber composite materials after neutron irradiation using a Monte Carlo method, then imports the method into finite element software through a programming language to perform finite element modeling and complete simulation calculations of parameters such as tensile strength and tensile modulus, and finally establishes a simulation and analysis system for studying radiation damage and degradation of carbon fiber composite materials under neutron irradiation.

[0005] To achieve the above purpose, the technical solution of the present invention is: The mechanical properties simulation method based on Monte Carlo-finite element simulation of carbon fiber composite material defects includes the following steps: S1 performs structural analysis on carbon fiber composite materials; S2 simplified and constructed the carbon fiber RVE model in Monte Carlo software, and filled it with epoxy resin material to complete the construction of the overall carbon fiber composite material RVE model; S3 sets the irradiation physical reaction process and performs neutron irradiation simulation; S4 constructs a finite element RVE model containing void defects in finite element software; S5 performs material parameter setting and unit periodicity analysis on the finite element RVE model to obtain the elastic constant matrix of the overall RVE model; S6 builds a macroscopic tensile finite element model, sets material parameters and simulation boundary conditions for the macroscopic model; S7 adds tensile load parametric sweep to perform macro tensile simulation.

[0006] Where: RVE is the representative volume element, Furthermore, in step S1, the carbon fiber composite material structure is analyzed by microscopic observation.

[0007] Furthermore, the step S3 specifically includes the following steps: S31 sets different neutron fluences to simulate the particle motion trajectory of incident particles in the composite material RVE model; S32 counts the vacancy defect information generated inside carbon fiber and epoxy resin in composite materials respectively; S33 converts the vacancy defect information generated inside into defects inside the material through a volume conversion formula; S34 converts defect information into the percentage of mass loss within the material.

[0008] Furthermore, the neutron flux is 1x10 12 n / cm 2 Up to 7x10 12 n / cm2 .

[0009] Furthermore, the mass loss percentage includes the mass loss percentage of the epoxy resin matrix and the mass loss percentage of the carbon fiber region.

[0010] Furthermore, the calculation formula for the mass loss ratio of the epoxy resin matrix is: in is the percentage of total atomic mass loss in the epoxy resin matrix, It is C 12 Atom loss number of atoms, m0 is C 12 Atomic mass, is the number of lost H atoms, m1 is the mass of H atoms, and Z is the mass of O 16 Atomic loss number of atoms, m2 is O 16 Atomic mass, is the density of epoxy resin matrix, V RVE is the composite RVE volume; The calculation formula for the mass loss ratio of the carbon fiber area is: in is the percentage of total atomic mass loss in the carbon fiber region, C is C 12 Atomic loss number of atoms, m3 is C 12 Atomic mass, It is the density of carbon fiber.

[0011] Furthermore, the physical model adopted in the physical reaction process is one of elastic scattering, inelastic scattering and neutron capture.

[0012] In particular, the RVE volume of the composite material is set to 1 mm 3 Furthermore, the step S4 is specifically as follows: S41 Write a defect random distribution algorithm in finite element software; S42 inputs the internal mass loss percentage statistically analyzed in the neutron irradiation simulation into the defect random distribution algorithm to construct a finite element RVE model containing void defects.

[0013] Specifically, the material parameters in step S5 include: Young's modulus E of the carbon fiber in three directions f1 , E f2 , E f3 , the shear modulus G of carbon fiber in three shear directions f12 , G f13 , G f23 , Poisson's ratio v of carbon fiber in three directions 12 , v 13 , v23 , the density of carbon fiber ρ2, the Young's modulus of epoxy resin matrix E m , the shear modulus of the epoxy resin matrix G m , Poisson's ratio V of epoxy resin matrix m , the density of epoxy resin ρ1, ε is the filling factor (carbon fiber volume fraction) of the fiber bundle.

[0014] Furthermore, the step S41 is specifically as follows: S411 defines the size of the RVE model and carbon fiber as well as the position in three-dimensional coordinates, and sets a small cube of a fine defect model; S412 Added constraints on the location of small defects in carbon fiber and epoxy resin S413 detects whether small defects overlap. If so, the position is invalid. If not, the position is valid.

[0015] Specifically, the composite material RVE model is a cube with a side length of 1 mm, the carbon fiber cylindrical model has a radius of 0.282 mm, and the small defect model cube has a side length of 0.05 mm.

[0016] Furthermore, the elastic constants in step S5 include the isotropic tensile modulus and isotropic shear modulus of the overall finite element RVE model, and the isotropic tensile modulus calculation formula is: Among them, E 11 is the longitudinal tensile modulus of RVE; E 22 , E 33 E is the tensile modulus of RVE in transverse and thickness directions; f1 is the longitudinal tensile modulus of the fiber, E f2 E is the transverse tensile modulus of the fiber; m is the tensile modulus of the matrix; ε is the filling factor of the fiber bundle; The calculation formula of the isotropic shear modulus is: Among them, G 12 , G 13 is the longitudinal shear modulus; G 23 is the transverse shear modulus; G f12 is the longitudinal shear modulus of the fiber; G f23 is the longitudinal shear modulus of the fiber; G m is the matrix and shear modulus v 12 、v 13 is the longitudinal Poisson of the fiber bundle; V 23 is the transverse Poisson’s ratio; v m is the matrix Poisson’s ratio, v f12 is the Poisson's ratio in the longitudinal direction of the fiber.

[0017] Specifically, in step S6, a component is reconstructed as a macro model of carbon fiber composite materials according to the national standard GBT / 3354-2014 "Test method for tensile properties of oriented fiber reinforced polymer matrix composite materials", and the elastic constant matrix material in step S4 is linked to the macro model material setting.

[0018] Furthermore, in step S7, the macroscopic tensile simulation results can be used to calculate the tensile strength and tensile modulus of the entire composite material. The tensile strength formula is: where σ t is the mechanical simulation stress, P max is the maximum breaking load when tension or compression is applied, W is the width of the specimen gauge section, and h is the thickness of the specimen gauge section; The tensile modulus formula is: Where Δσ is the stress change, Δε is the strain change, and E t is the mechanical simulation modulus.

[0019] Beneficial effects of the present invention: 1. The present invention theoretically calculates the displacement damage effect of the internal area of ​​the unidirectional carbon fiber composite material, uses the Monte Carlo method to simulate the random incidence of neutrons in the RVE model of the carbon fiber composite material, and introduces defects in the RVE to simulate the long-term damage caused by neutron irradiation by importing the defect law information induced by neutron irradiation. Finally, the mechanical properties caused by irradiation damage are calculated through the visualization window in combination with the finite element function characteristics. The method is easy to operate, has high calculation efficiency, accurate calculation results, and low economic cost. It solves the problems of high cost and long time of traditional irradiation experiments and mechanical experiments, and provides a technical basis for the reliability assessment research of carbon fiber composite materials in radiation scenarios, saving a lot of time and economic costs.

[0020] 2. The technical solution of the present invention can simulate the mechanical properties caused by internal defects of materials under different energies and different injection rates, and can solve the energy conditions that are difficult to achieve in actual irradiation experiments. It can also simulate the mechanical properties through simulation under some extreme energy or injection conditions, and provide a basis for studying the reliability of composite materials in extreme radiation scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. For those skilled in the art, other drawings can be obtained based on the drawings without paying creative work.

[0022] Figure 1 The flowchart of the mechanical property simulation method of the present invention based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects; Figure 2 A simplified carbon fiber RVE ideal model provided by the present invention; Figure 3 A medium-scale carbon fiber RVE model provided by the Monte Carlo software of the present invention; Figure 4 The isometric carbon fiber RVE model provided by the present invention is filled with an epoxy resin matrix; Figure 5 A schematic diagram of the neutron irradiation physical reaction process provided by the present invention; Figure 6 A schematic diagram of a simulation of a neutron-irradiated carbon fiber-epoxy resin composite material provided by the present invention; Figure 7 A schematic diagram of the present invention for counting all vacancy defect information and converting it into a quality damage ratio; Figure 8 The present invention provides a defect random distribution algorithm in finite element software; Fig. 9 The random defect modeling in the finite element software provided by the present invention; Fig.10 The unit periodic boundary condition setting provided by the present invention; Fig.11 The elastic constant matrix for obtaining RVE provided by the present invention; Fig.12 A macro tensile specimen model provided by the present invention; Fig.13 A schematic diagram of linking the elastic constant matrix material to the macro model provided by the present invention; Fig.14 The present invention provides for setting and simulating mechanical boundary conditions for the macro model; Fig.15 The Von Mises cloud diagram of tensile stress of the ideal model under the failure load provided by the present invention; Fig.16 The present invention provides a neutron irradiation of 1x10 12n / cm 2 Von mises cloud diagram of tensile stress; Fig.17 The present invention provides a neutron irradiation of 7x10 12 n / cm 2 Von mises cloud diagram of tensile stress; Fig.18 The present invention provides a neutron irradiation of 1x10 13 n / cm 2 Von mises cloud diagram of tensile stress; Fig.19 The modulus calculated (slope value) according to the strain-stress curve data provided by the present invention; Fig. 20 Comparison of the tensile strength experiment and simulation data before and after neutron irradiation provided by the present invention; Fig.21 Comparison of the tensile modulus experiment and simulation data before and after neutron irradiation provided by the present invention; Fig. 22 The neutron irradiation provided by the present invention is 1x10 13 n / cm 2 Lower tensile strength; Fig.23 The neutron irradiation provided by the present invention is 1x10 13 n / cm 2 Lower tensile modulus; Fig.24 Schematic diagram of the generation of vacancy defects inside the material provided by the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, the present invention provides a mechanical property simulation method for simulating defects of carbon fiber composite materials based on Monte Carlo-finite element method, comprising the following steps: S1 performs structural analysis on carbon fiber composite materials; S2 simplified and constructed the carbon fiber RVE model in Monte Carlo software, and filled it with epoxy resin material to complete the construction of the overall carbon fiber composite material RVE model; S3 sets the irradiation physical reaction process and performs neutron irradiation simulation; S4 constructs a finite element RVE model containing void defects in finite element software; S5 performs material parameter setting and unit periodicity analysis on the finite element RVE model to obtain the elastic constant matrix of the overall RVE model; S6 builds a macroscopic tensile finite element model, sets material parameters and simulation boundary conditions for the macroscopic model; S7 adds tensile load parametric sweep to perform macro tensile simulation.

[0025] Step S3 of the present invention is specifically: S31 sets different neutron fluences to simulate the particle motion trajectory of incident particles in the composite material RVE model; S32 counts the vacancy defect information generated inside carbon fiber and epoxy resin in composite materials respectively; S33 converts the vacancy defect information generated inside into defects inside the material through a volume conversion formula; S34 converts defect information into the percentage of mass loss within the material.

[0026] The physical model used in the physical reaction process is one of elastic scattering, inelastic scattering and neutron capture.

[0027] Step S4 of the present invention is specifically as follows: S41 Write a defect random distribution algorithm in finite element software; S42 inputs the internal mass loss percentage statistically analyzed in the neutron irradiation simulation into the defect random distribution algorithm to construct a finite element RVE model containing void defects.

[0028] Step S41 of the present invention is specifically as follows: S411 defines the size of the RVE model and carbon fiber as well as the position in three-dimensional coordinates, and sets a small cube of a fine defect model; S412 Add constraints for locations where small defects occur in carbon fiber and epoxy resin respectively S413 detects whether small defects overlap. If so, the position is invalid. If not, the position is valid.

[0029] In step S5 of the present invention, the elastic constants include the isotropic tensile modulus and isotropic shear modulus of the overall finite element RVE model, and the tensile modulus and shear modulus can be calculated according to the calculation formula.

[0030] In step S7 of the present invention, the macroscopic tensile simulation results can be used to calculate the tensile strength and tensile modulus of the overall composite material. Specifically, refer to Figures 2 to 7 , which is the process of converting mass damage percentage of carbon fiber composite materials simulating neutron irradiation damage using Monte Carlo software Geant4.

[0031] First, Figure 2 As shown, the structure of the carbon fiber composite material is analyzed and a simplified RVE ideal model is constructed. Specifically, the structure of the carbon fiber composite material is observed and analyzed through a microscope, and it is observed that the internal structure of the composite material is mainly columnar carbon fiber materials arranged in the same direction, and the fiber gaps are filled with epoxy resin. Then, based on the results of observation and analysis, a simplified RVE (representative volume element) ideal model of the composite material is constructed. The representative volume element is a unit cell structure of the carbon fiber composite material, in which the carbon fiber consists of a middle cylinder and a quarter of the cylinders around it, and the epoxy resin consists of other regional parts.

[0032] Secondly, Figure 3 and Figure 4 In the Monte Carlo Geant4 software, an equal-scale RVE model was established. Figure 5 The neutron irradiation physical reaction process is set as shown in the figure. The physical model of the physical reaction process adopts physical models such as elastic scattering, inelastic scattering, and neutron capture, and simulates the particle motion trajectory of the incident particles in the composite material RVE under different energies and different neutron injections. Figure 6 The neutron irradiation simulation is finally Figure 7 The parameter information of all secondary particles is counted. Each secondary particle that leaves its original position represents a vacancy defect, which can be further converted into defects inside the material. Finally, the defect information is converted into the percentage of mass loss inside the material. The mass loss inside the material is the sum of the internal defects.

[0033] like Fig.24 As shown, when the neutron collides with atom A, the energy is transferred linearly to the lattice atoms. When the energy reaches the displacement threshold energy of the lattice atoms, the lattice atoms shift and leave vacancy defects in place. The displaced atoms continue to produce displacement effects with other atoms, thereby generating cascade defects, namely cluster defects, and even voids B.

[0034] The secondary particle parameter information includes the information of the lattice atoms leaving the original position and arriving at the predetermined position. The position left has a vacancy defect. In this embodiment, only the vacancy defect information needs to be simulated. The vacancy defect information includes the number and position of defects. The defect information obtained by Monte Carlo software includes the number and position of vacancy defects.

[0035] The internal mass loss ratio of the material is divided into the atomic mass loss ratio in the epoxy resin group and the atomic mass loss ratio in the carbon fiber area. The relevant formula is: in is the percentage of total atomic mass loss in the epoxy resin matrix, It is C12 Atom loss number of atoms, m0 is C 12 The atomic mass is 1.993*10-26kg. is the number of lost H atoms, m1 is the mass of the H atom, which is 1.6726*10-27kg, and Z is O 16 Atomic loss number of atoms, m2 is O 16 The atomic mass is 2.6573*10-26kg, is the density of epoxy resin matrix, V RVE is the RVE volume, set to 1mm 3 ; in is the percentage of total atomic mass loss in the carbon fiber region, C is C 12 Atomic loss number of atoms, m3 is C 12 The atomic mass is 1.993*10-26kg. It is the density of carbon fiber.

[0036] refer to Figures 8 to 14 , which is a finite element based multi-scale modeling and simulation calculation process.

[0037] like Figure 8 As shown, the built-in programming module of the finite element software COMSOL is used to write a defect random distribution algorithm. The algorithm code first defines the size of the RVE model (cube with a side length of 1mm) and the carbon fiber (cylindrical model radius 0.282mm) as well as the position in the three-dimensional coordinates, and sets a small defect model small cube with a side length of 0.05mm. Secondly, the position constraint code for the occurrence of small defects is added. Different small defects need to be set in the carbon fiber and epoxy resin respectively. Then, the code for randomizing small defects within the constraint range is written. Finally, the code for checking whether small defects overlap is written. If there is overlap, the position is invalid. If there is no overlap, the position is valid. The statistical internal mass loss ratio of the material is input into the random algorithm, and the volume of a single small defect is set to 0.000125mm 3 .like Fig. 9 As shown in the figure, a random defect RVE model containing carbon fiber and matrix defects is constructed in the finite element software COMSOL, and the material parameters of carbon fiber and epoxy resin are set for the model. The material parameters include: Young's modulus E f1 , E f2 , E f3 , the shear modulus G of carbon fiber in three shear directions f12 , G f13 , G f23 , Poisson's ratio v of carbon fiber in three directions 12 , v 13 , v23 , the density of carbon fiber ρ2, the Young's modulus of epoxy resin matrix E m , the shear modulus of the epoxy resin matrix G m , Poisson's ratio V of epoxy resin matrix m , the density of epoxy resin ρ1, ε is the filling factor of the fiber bundle (carbon fiber volume fraction). Fig.10 As shown in the figure, the unit periodic boundary conditions are set according to the material parameters, specifically, three boundary pairs are applied to the composite material RVE model, respectively stretching the X, Y, and Z simulations and shearing the XY, XZ, and YZ directions. Fig.11 As shown in the figure, based on the material parameters and unit periodic boundary conditions, the elastic constant matrix of the overall RVE model is obtained, which is the mesoscale RVE simulation.

[0038] The formula used to calculate the effective elastic constant matrix data for unit periodicity is: Among them, Fig.11 As shown in the above formula, E 11 , E 22 , E 33 , G 12 , G 13 , G 23 Corresponding to the diagonal data respectively.

[0039] After completing the simulation of mesoscale RVE, it is necessary to realize the transition from mesoscale to macroscale, such as Fig.12 As shown in the figure, the macroscopic tensile mechanical model of carbon fiber composite materials is constructed according to the national standard GBT / 3354-2014 "Test method for tensile properties of oriented fiber reinforced polymer matrix composites", as shown in the figure. Fig.13 Link the elastic constant matrix material to the macromodel material settings as shown in . Fig.14 As shown in the figure, the simulation boundary conditions of the macro model are set.

[0040] refer to Figures 15 to 19 , which is the output result diagram of tensile stress and tensile modulus of finite element simulation.

[0041] After setting the macro-model simulation boundary conditions, set the macro-simulation steady-state solver, add the tensile load parametric sweep, and add the stress Von mises maximum value probe and the first principal strain probe in the macro-model gauge section. Simulate and calculate the stress Von mises simulation cloud map under the failure load. The stress Von mises under this failure load can be regarded as the strength, and the modulus (slope value) is calculated based on the strain-stress curve data, such as Fig.15 As shown, the ideal model under the failure load is drawn, as Fig.16 As shown, the neutron irradiation is 1x1012 n / cm 2 When drawing the tensile stress Von mises cloud diagram, such as Fig.17 Neutron irradiation shown is 7x10 12 n / cm 2 When drawing the tensile stress Von mises cloud diagram, Fig.18 The results of stress Von Mises fitting modulus data are shown as follows: Fig.19 As shown, the neutron irradiation is 1x10 13 n / cm 2 When drawing the tensile stress Von mises cloud diagram.

[0042] The above stress Von Mises is von Mises stress, which is an equivalent stress based on shear strain energy.

[0043] The tensile strength calculation formula is as follows:

[0044] And the tensile modulus calculation formula is as follows:

[0045] In order to verify the accuracy of the simulation results, the tensile properties test of carbon fiber composite materials before and after neutron irradiation were compared with the simulation data.

[0046] like Fig. 20 and Fig.21 As shown, it is a schematic diagram comparing the tensile properties test and simulation data of carbon fiber composite materials before and after neutron irradiation.

[0047] like Fig. 20 As shown, in the unirradiated state, the neutron injection is 1x10 12 n / cm 2 、Neutron injection up to 7x10 12 n / cm 2 The experimental tensile strength of the carbon fiber composite material was 2301.01MPa, 2355.82MPa, and 2375MPa, respectively, while the simulated tensile strength was 2315.15MPa, 2340.15MPa, and 2372.46MPa, respectively. After the neutron irradiation injection accumulation, the experimental tensile strength and simulated tensile strength of the material were correspondingly improved, and the maximum difference between the experimental results and the simulation results was only 0.665%, as shown in Table 1: Table 1 Comparison of test and simulation data of tensile strength of carbon fiber composites before and after neutron irradiation Unirradiated state <![CDATA[1x10 12 n / cm 2 ]]> <![CDATA[7x10 12 n / cm 2 ]]> Experimental tensile strength MPa 2301.01 2355.82 2375 Simulated tensile strength MPa 2315.15 2340.15 2372.46 Deviation percentage % 0.614 0.665 0.107 like Fig.21 As shown, in the unirradiated state, the neutron injection is 1x10 12n / cm 2 、Neutron injection up to 7x10 12 n / cm 2 The experimental tensile modulus of the carbon fiber composite material was 136.362GPa, 135.412GPa, 135.921GPa, respectively, while the simulated tensile modulus was 128.003GPa, 128.281GPa, 128.911GPa, respectively. After the neutron irradiation injection accumulation, the experimental tensile strength and simulated tensile strength of the material have slight changes, and the maximum difference between the experimental results and the simulation results is only 6.1%, which is much less than 10%, as shown in Table 2: Table 2 Comparison of tensile modulus test and simulation data of carbon fiber composites before and after neutron irradiation Unirradiated state <![CDATA[1x10 12 n / cm 2 ]]> <![CDATA[7x10 12 n / cm 2 ]]> Experimental tensile modulus GPa 136.362 135.412 135.921 Simulated tensile modulus GPa 128.003 128.281 128.911 Deviation percentage % 6.13 5.266 5.157 It can be seen from Tables 1 and 2 that the comparison error between the experimental and simulation data of the tensile modulus and tensile modulus of carbon fiber composites before and after neutron irradiation is very small, indicating that this method can well simulate the degradation law of mechanical properties of carbon fiber composites after neutron irradiation damage.

[0048] like Figure 22 to Figure 23 As shown in the figure, carbon fiber composites were also tested at neutron injection of 1x10 13 n / cm 2 The simulation data of carbon fiber composite materials with neutron injection of 1x10 13 n / cm 2 Tensile strength and tensile modulus.

[0049] In this embodiment, the simulated physical model is the result of different injections under the condition of constant incident particle energy, but changing the energy of the incident particles can also be simulated through the technical solution of the present invention.

[0050] In this embodiment, the simulated different fluence data cannot be exhaustively listed. As long as the energy and number of particles that can excite particles and generate particle irradiation are achieved, simulation can be performed using the technical solution of the present invention.

[0051] Although the preferred implementation cases of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms of specific changes without departing from the scope of protection of the invention spirit and claims, which all fall within the scope of protection of the present invention.

Claims

1. A mechanical properties simulation method for simulating defects in carbon fiber composite materials based on Monte Carlo-finite element method, characterized in that: The following steps are involved: S1 performs structural analysis on carbon fiber composite materials; S2 simplified and constructed the carbon fiber RVE model in Monte Carlo software, and filled it with epoxy resin material to complete the construction of the overall carbon fiber composite material RVE model; S3 sets the irradiation physical reaction process and performs neutron irradiation simulation; S4 constructs a finite element RVE model containing void defects in finite element software; S5 sets material parameters for the finite element RVE model, sets unit periodic boundary conditions, and obtains the elastic constant matrix of the overall RVE model; S6 builds a macroscopic tensile finite element model, sets material parameters and simulation boundary conditions for the macroscopic model; S7 adds tensile load parametric sweep to perform macro tensile simulation.

2. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 1 is characterized in that: In the step S1, the carbon fiber composite material structure is analyzed by microscopic observation.

3. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 1 is characterized in that: The step S3 comprises the following steps: S31 sets different neutron fluences to simulate the particle motion trajectory of incident particles in the composite material RVE model; S32 counts the vacancy defect information generated inside carbon fiber and epoxy resin in composite materials respectively; S33 converts the vacancy defect information generated inside into defects inside the material through a volume conversion formula; S34 converts defect information into the percentage of mass loss within the material.

4. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 3 is characterized in that: The neutron fluence is 0 to 1x10 13 n / cm 2 .

5. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 4 is characterized in that: The mass loss ratio includes the mass loss ratio of the epoxy resin matrix and the mass loss ratio of the carbon fiber area; The calculation formula for the mass loss ratio of the epoxy resin matrix is: in is the percentage of total atomic mass loss in the epoxy resin matrix, It is C 12 Atom loss number of atoms, m0 is C 12 Atomic mass, is the number of lost H atoms, m1 is the mass of H atoms, Z is O 16 Atomic loss number of atoms, m2 is O 16 Atomic mass, is the density of epoxy resin matrix, V RVE is the RVE volume; The calculation formula for the mass loss ratio of the carbon fiber area is: in is the percentage of total atomic mass loss in the carbon fiber region, C is C 12 Atomic loss number of atoms, m3 is C 12 Atomic mass, It is the density of carbon fiber.

6. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to any one of claims 3 to 5, characterized in that: The physical model adopted in the physical reaction process is one of elastic scattering, inelastic scattering and neutron capture.

7. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 1 is characterized in that: The step S4 is specifically as follows: S41 Write a defect random distribution algorithm in finite element software; S42 inputs the internal mass loss percentage statistically analyzed in the neutron irradiation simulation into the defect random distribution algorithm to construct a finite element RVE model containing void defects.

8. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 8, characterized in that: The step S41 is specifically as follows: S411 defines the RVE model of the composite material and the size of the carbon fiber as well as the position in three-dimensional coordinates, and sets a small cube of a fine defect model; S412 Add constraints for locations where small defects occur in carbon fiber and epoxy resin respectively S413 detects whether small defects overlap. If so, the position is invalid. If not, the position is valid.

9. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 1, characterized in that: The elastic constants in step S5 include the isotropic tensile modulus and isotropic shear modulus of the overall finite element RVE model, and the isotropic tensile modulus calculation formula is: Among them, E 11 is the longitudinal tensile modulus of RVE; E 22 , E 33 E is the tensile modulus of RVE in transverse and thickness directions; f1 is the longitudinal tensile modulus of the fiber, E f2 E is the transverse tensile modulus of the fiber; m is the tensile modulus of the matrix; ε is the filling factor of the fiber bundle, that is, the volume fraction of carbon fiber in the composite material; The calculation formula of the isotropic shear modulus is: Among them, G 12 , G 13 is the longitudinal shear modulus; G 23 is the transverse shear modulus; G f12 is the longitudinal shear modulus of the fiber; G f23 is the longitudinal shear modulus of the fiber; G m is the matrix and shear modulus v 12 、v 13 is the longitudinal Poisson of the fiber bundle; V 23 is the transverse Poisson's ratio; v m is the matrix Poisson’s ratio, v f12 is the longitudinal Poisson’s ratio of the fiber, and ε is the filling factor of the fiber bundle.

10. The mechanical properties simulation method based on Monte Carlo-Finite Element Simulation of Carbon Fiber Composite Material Defects according to claim 1, characterized in that: In step S7, the macroscopic tensile simulation results can be used to calculate the tensile strength and tensile modulus of the entire composite material. The tensile strength formula is: where σ t is the mechanical simulation stress, P max is the maximum breaking load when tension or compression is applied, W is the width of the specimen gauge section, and h is the thickness of the specimen gauge section; The tensile modulus formula is: Where Δσ is the stress change, Δε is the strain change, and E t is the mechanical simulation modulus.

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