A multi-scale analytical method for simulating graphene oxide reinforced nylon composites

Abstract

This invention belongs to the technical field of analyzing graphene oxide content in composite materials. It addresses the difficulty of accurately controlling the nanoscale content of graphene oxide in composite materials using traditional experimental methods. It provides a multi-scale analytical method for simulating graphene oxide-reinforced nylon composites: using nylon as the matrix and graphene oxide as an inclusion; varying the volume fraction of the inclusion to generate multiple molecular dynamics models of the graphene oxide / nylon composite; and using nylon as the matrix and the composite material from the optimal molecular dynamics model of the graphene oxide / nylon composite as an inclusion; varying the volume fraction of the inclusion to generate multiple finite element models of the graphene oxide / nylon composite. This method combines molecular dynamics simulation with finite element simulation to reveal the behavior and properties of composite materials at different scales, helping to optimize the structure and properties of composite materials.

Description

Technical Field

[0001] The invention belongs to the technical field of graphene oxide content analysis in composite materials, and particularly relates to an analysis method for multi-scale simulated graphene oxide reinforced nylon composite materials. Background Art

[0002] Graphene oxide is a nanofiller with excellent mechanical properties and chemical stability. Its high surface area, high mechanical strength, and excellent thermal conductivity make it an ideal candidate for reinforcing composites. However, accurately determining the graphene oxide content in composites is crucial for achieving optimal properties. Therefore, developing an accurate and reliable analytical method to determine the graphene oxide content in composites is crucial.

[0003] Currently, commonly used experimental methods for measuring the content of graphene oxide in composite materials have some limitations, such as complex operations, time-consuming and labor-intensive processes, and the inability to achieve precise control at the nanoscale. Therefore, the use of computational simulation methods to analyze the content of graphene oxide in composite materials is of great significance.

[0004] Multiscale simulation is an effective computational method that can reveal the behavior and properties of materials at different scales. By combining molecular dynamics simulations with finite element simulations, the graphene oxide content in composite materials can be analyzed and predicted at both atomic and macroscales. This multiscale simulation approach can provide a deep understanding of the mechanical properties, structural characteristics, and interactions of composite materials.

[0005] Therefore, developing a multi-scale analytical method for simulating graphene oxide reinforced nylon composites can provide important guidance and optimization paths for the design and preparation of composites, and promote the performance improvement and application expansion of composites. Summary of the Invention

[0006] In order to solve at least one of the above-mentioned technical problems existing in the prior art, the present invention provides an analysis method for multi-scale simulation of graphene oxide reinforced nylon composite materials.

[0007] The present invention is implemented by the following technical solution: a multi-scale simulation analysis method of graphene oxide reinforced nylon composite material, comprising the following steps:

[0008] S1: Construct a molecular dynamics model of graphene oxide / nylon composites, where nylon is the matrix and graphene oxide is the inclusion. The volume fraction of the inclusion is varied to generate multiple molecular dynamics models of the graphene oxide / nylon composites.

[0009] S2: Simulate the motion of graphene oxide / nylon composites at the microscopic level to determine the molecular dynamics model of graphene oxide / nylon composites with optimal mechanical properties and the volume fraction of graphene oxide under this model;

[0010] S3: constructing a finite element model of a graphene oxide / nylon composite material, wherein nylon is used as a matrix, the composite material in the optimal molecular dynamics model of the graphene oxide / nylon composite material is used as an inclusion, and the volume fraction of the inclusion is changed to generate multiple finite element models of the graphene oxide / nylon composite material;

[0011] S4: Based on the simulation results of the finite element model, determine the finite element model of the graphene oxide / nylon composite material with the best mechanical properties and the largest equivalent elastic modulus and the volume fraction of graphene oxide under this model;

[0012] S5: The mechanical properties of inclusions and matrix, and the volume fraction of inclusions in the optimal molecular dynamics model of graphene oxide / nylon composite materials are brought into the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, and compared and mutually verified with the optimal molecular dynamics model of graphene oxide / nylon composite materials; the mechanical properties of inclusions and matrix in the optimal molecular dynamics model of graphene oxide / nylon composite materials and the volume fraction of inclusions in the optimal finite element model of graphene oxide / nylon composite materials are brought into the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, and compared and mutually verified with the optimal finite element model of graphene oxide / nylon composite materials; the optimal theoretical model suitable for characterizing the mechanical properties of graphene oxide / nylon composite materials is obtained.

[0013] Preferably, in step S1, the edges of the graphene sheets of graphene oxide are oxidized to carboxyl groups and combined with nylon, where nylon is a nylon chain polymerized from nylon monomers. A molecular dynamics model of a mixture of 2 chains, 4 chains, 6 chains, 8 chains, 10 chains, 12 chains, 14 chains and 16 chains is established, and a molecular dynamics model of a graphene oxide / nylon composite material is constructed together with the molecular dynamics model of graphene oxide.

[0014] Preferably, in step S2, LAMMPS is used to simulate the mechanical behavior and interaction of the composite material at the atomic scale, and the molecular dynamics simulation includes LAMMPS performing force field selection, step size setting, boundary condition selection, energy minimization setting, relaxation mode and time, and uniaxial stretching parameter setting.

[0015] Preferably, the initial time step of the molecular dynamics model of the graphene oxide / nylon composite material is set to 0.05 fs, periodic boundary conditions are set, and the conjugate gradient method is selected in the process of energy minimization; the relaxation mode, time and uniaxial stretching steps include:

[0016] T1: During the relaxation process, the model is first relaxed for 1000 fs at 100 K in the NVT ensemble, and then relaxed for 1000 fs in the NPT ensemble.

[0017] T2: Change the temperature to 300 K, relax for 1000 fs, then relax for 1000 fs in the NVT ensemble, then gradually increase the temperature to 500 K over 1000 fs, and relax for another 1000 fs;

[0018] T3: Lower the model temperature from 500K to 300K within 1000fs, and then relax for another 1000fs;

[0019] T4: At a temperature of 100 K, the NPT ensemble was selected, and the relaxation time was 25000 fs. Finally, the NVT ensemble was relaxed for 250 fs, and then uniaxial stretching was performed.

[0020] Preferably, in the molecular dynamics model of the graphene oxide / nylon composite material, the expression for the measure ξ of the elastic modulus of the graphene oxide reinforced nylon is:

[0021]

[0022] Where ξ is a measure of the elastic modulus of graphene oxide reinforced nylon; E(PA) is the elastic modulus of nylon; and E(k) is the elastic modulus of the composite material. This allows the molecular dynamics model of the graphene oxide / nylon composite material with optimal mechanical properties to be determined.

[0023] Preferably, the method for selecting the optimal size of the molecular dynamics model of the graphene oxide / nylon composite material is as follows: pre-setting the dimensions of the molecular dynamics model of the graphene oxide / nylon composite material in the xy direction, establishing n molecular dynamics models of the graphene oxide / nylon composite material along the z direction of the molecular dynamics model of the graphene oxide / nylon composite material, finding the molecular dynamics model of the graphene oxide / nylon composite material when the mechanical properties of the composite material along the z direction are optimal, and recording the dimension of the model in the z direction as zl; keeping the height of the molecular dynamics model of the graphene oxide / nylon composite material in the z direction as zl, changing the dimension in the xy direction, establishing m molecular dynamics models of the graphene oxide / nylon composite material along the xy plane of the molecular dynamics model of the graphene oxide / nylon composite material, finding the molecular dynamics model of the graphene oxide / nylon composite material when the mechanical properties of the composite material along the xy plane are optimal, recording the dimensions of the model in xy as xl and yl, where xl, yl, and zl are the optimal dimensions of the molecular dynamics model of the graphene oxide / nylon composite material to be established.

[0024] Preferably, in step S3, in order to ensure that the graphene oxide does not overlap with each other in nylon, finite element models of graphene oxide / nylon composite materials with graphene oxide volume fractions of 1%, 5%, 10%, 15% and 20% are established respectively for numerical simulation. By calculating the finite element model, the finite element model of the graphene oxide / nylon composite material with the optimal mechanical properties and the largest equivalent elastic modulus and the volume fraction of graphene oxide in the model are determined.

[0025] Preferably, in step S5, the parameters input into the self-consistent theory model, the Mori-Tanaka model, and the Double-Inclusion model are: elastic tensors of inclusions and matrix, and volume fraction of inclusions; the parameters input into the Halpin-Tsai model are: elastic moduli of inclusions and matrix, and volume fraction of inclusions.

[0026] Preferably, a comprehensive evaluation is performed on the four theoretical models of the self-consistent theoretical model, the Mori-Tanaka model, the Double-Inclusion model, and the Halpin-Tsai model; the evaluation formula is defined as:

[0027]

[0028]

[0029]

[0030] In the formula, e is the evaluation factor of the model, E t is the result of the theoretical model, E e is the finite element model result, E mis the molecular dynamics model result, e1 is the percentage compared with the finite element result, and e2 is the percentage compared with the molecular dynamics result.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This method accurately establishes a molecular dynamics model of graphene oxide / nylon composites at the atomic scale and accurately determines the graphene oxide content through simulation and calculation. Combining molecular dynamics simulations with finite element modeling reveals the behavior and properties of the composite at different scales, helping to optimize its structure and properties. This method allows for flexible adjustment of model parameters and conditions to suit different composite systems and research needs, potentially expanding its application to other material systems and engineering fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a molecular dynamics model diagram of graphene oxide / nylon composite material;

[0035] Figure 2 are the energy and pressure changes of the model during the relaxation process;

[0036] Figure 3 This is a graph showing the fracture position analysis of the graphene oxide / nylon composite material using a molecular dynamics model.

[0037] Figure 4 It is the stress cloud diagram of uniaxial tension of graphene oxide / nylon composite material under molecular dynamics simulation;

[0038] Figure 5 are eight molecular dynamics models of graphene oxide / nylon composites along the z direction;

[0039] Figure 6 are eight molecular dynamics models of graphene oxide / nylon composites along the xy plane;

[0040] Figure 7 is the mechanical properties of the molecular dynamics model (z1-z8) of graphene oxide / nylon composites;

[0041] Figure 8 is the mechanical properties of the molecular dynamics model (xy1-xy8) of graphene oxide / nylon composites;

[0042] Figure 9 It is the model data of the molecular dynamics model of graphene oxide / nylon composite materials with the best mechanical properties;

[0043] Figure 10 is the isotropic uniaxial tension and isotropic shear diagram;

[0044] Figure 11 is to establish a cross-scale model of graphene oxide / nylon composites;

[0045] Figure 12 It is the stress cloud diagram during the uniaxial tension process of the finite element;

[0046] Figure 13 is the stress cloud diagram of graphene oxide during uniaxial stretching;

[0047] Figure 14 It is a comparison between the theoretical model results and the finite element results and molecular dynamics results.

[0048] In the figure: 1-graphene oxide; 2-nylon. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention are clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other implementations derived by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0050] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention. It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0051] The present invention provides an embodiment:

[0052] like Figures 1 to 14 As shown, a multi-scale simulation analysis method for graphene oxide reinforced nylon composites includes the following steps:

[0053] S1: Use Materials Studio to construct molecular dynamics models of graphene oxide and nylon, including selecting appropriate force field models and parameters and performing initial structural optimization. Nylon is used as the matrix and graphene oxide as the inclusion. By keeping the inclusion constant and varying the volume of the matrix, the volume fraction of the inclusion relative to the composite material is altered, generating multiple molecular dynamics models of the graphene oxide / nylon composite material.

[0054] S2: Simulate the motion of the graphene oxide / nylon composite at the microscopic level. Based on the molecular dynamics simulation results, determine the molecular dynamics model of the graphene oxide / nylon composite with the optimal mechanical properties and the volume fraction of graphene oxide under this model.

[0055] S3: constructing a finite element model of a graphene oxide / nylon composite material, wherein nylon is used as a matrix, the composite material in the optimal molecular dynamics model of the graphene oxide / nylon composite material is used as an inclusion, and the volume fraction of the inclusion is changed to generate multiple finite element models of the graphene oxide / nylon composite material;

[0056] S4: Based on the simulation results of the finite element model, determine the finite element model of the graphene oxide / nylon composite material with the best mechanical properties and the largest equivalent elastic modulus and the volume fraction of graphene oxide under this model;

[0057] S5: The mechanical properties of inclusions and matrix, and the volume fraction of inclusions in the optimal molecular dynamics model of graphene oxide / nylon composite materials are brought into the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, and compared and mutually verified with the optimal molecular dynamics model of graphene oxide / nylon composite materials; the mechanical properties of inclusions and matrix in the optimal molecular dynamics model of graphene oxide / nylon composite materials and the volume fraction of inclusions in the optimal finite element model of graphene oxide / nylon composite materials are brought into the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, and compared and mutually verified with the optimal finite element model of graphene oxide / nylon composite materials; the optimal theoretical model suitable for characterizing the mechanical properties of graphene oxide / nylon composite materials is obtained.

[0058] In this example, graphene oxide is an ideally oxidized graphene sheet, with all edges of the sheet oxidized to carboxyl groups for effective bonding to the matrix. The sheet remains unoxidized to maintain the mechanical properties of the graphene. Nylon is polymerized from a single nylon monomer with 20 repeating units, forming a polymerized nylon chain. Molecular dynamics models of nylon with mixed chains of 2, 4, 6, 8, 10, 12, 14, and 16 chains were established to ensure applicability. Together with the molecular dynamics model of graphene oxide, a molecular dynamics model of a graphene oxide / nylon composite was constructed.

[0059] In step S2, LAMMPS is used to simulate the mechanical behavior and interactions of the composite material at the atomic scale. The molecular dynamics simulation includes LAMMPS selection of the force field, setting of the step size, selection of the boundary conditions, setting of the energy minimization, relaxation mode and time, and setting of the uniaxial stretching parameters.

[0060] The specific parameters are set as follows: the initial time step of the molecular dynamics model of graphene oxide / nylon composite material is set to 0.05fs, periodic boundary conditions are set, and the conjugate gradient method is selected in the energy minimization process; the relaxation mode, time and uniaxial stretching steps include:

[0061] T1: During the relaxation process, the model is first relaxed for 1000 fs at 100 K in the NVT ensemble, and then relaxed for 1000 fs in the NPT ensemble.

[0062] T2: Change the temperature to 300 K, relax for 1000 fs, then relax for 1000 fs in the NVT ensemble, then gradually increase the temperature to 500 K over 1000 fs, and relax for another 1000 fs;

[0063] T3: Lower the model temperature from 500K to 300K within 1000fs, and then relax for another 1000fs;

[0064] T4: At 100 K, relax for 25,000 fs in the NPT ensemble, and finally relax for 250 fs in the NVT ensemble, followed by uniaxial stretching.

[0065] In LAMMPS, the stress of each atom can be calculated. The stress during uniaxial stretching of the model can also be obtained by pressure equivalence, that is:

[0066]

[0067] Where: α and β represent atomic indices; m and v are the mass and velocity of the atom, respectively; i and j are indices in the Cartesian coordinate system; r αβ is the distance between α and β atoms; f αβis the force between α and β atoms; V is the volume of the atom.

[0068] Based on the molecular dynamics simulation results, the elastic phase of the curve was fitted by visualizing the stress-strain curve. In the molecular dynamics model of graphene oxide / nylon composite materials, the expression for the elastic modulus ξ of graphene oxide reinforced nylon is:

[0069]

[0070] Where ξ is a measure of the elastic modulus of graphene oxide reinforced nylon; E(PA) is the elastic modulus of nylon; and E(k) is the elastic modulus of the composite material. This allows the molecular dynamics model of the graphene oxide / nylon composite material with optimal mechanical properties to be determined.

[0071] like Figure 5 、 Figure 6 As shown, the method for selecting the optimal size of the molecular dynamics model of the graphene oxide / nylon composite material is as follows: the size of the molecular dynamics model of the graphene oxide / nylon composite material in the xy direction is pre-given, and eight molecular dynamics models of the graphene oxide / nylon composite material are established by stretching the molecular dynamics model of the graphene oxide / nylon composite material along the z direction, and the molecular dynamics model of the graphene oxide / nylon composite material when the mechanical properties of the composite material along the z direction are optimal is found, and the size of the model in the z direction is recorded as zl; while keeping the height of the molecular dynamics model of the graphene oxide / nylon composite material in the z direction as zl, the size in the xy direction is changed, and eight molecular dynamics models of the graphene oxide / nylon composite material are established by stretching the molecular dynamics model of the graphene oxide / nylon composite material along the xy plane, and the molecular dynamics model of the graphene oxide / nylon composite material when the mechanical properties of the composite material along the xy plane are optimal is found, and the xy sizes of the models are recorded as xl and yl, where xl, yl, and zl are the optimal sizes of the molecular dynamics model of the graphene oxide / nylon composite material to be established.

[0072] Figure 7 It can be seen that the mechanical properties of the z5 model are the best. After determining the height of the model z5 as the optimal height, the length and width of the model are changed, and the Figure 8 It can be concluded that the mechanical properties of the xy5 model are the best, and thus the molecular dynamics model of the graphene oxide / nylon composite material with the best mechanical properties is found with a length, width and height of 3.91172nm, 3.9117nm and 6.96478nm respectively. By studying and analyzing 16 molecular dynamics models of graphene oxide / nylon composite materials, the molecular dynamics model of the graphene oxide / nylon composite material with the best mechanical properties is obtained. The model data is as follows Figure 9 shown. Figure 3 It shows that as the height of the composite model increases, the location where the mechanical properties of the model fail shifts from near the graphene oxide to the nylon; Figure 4 The microscopic mechanism of graphene oxide reinforcement of nylon is shown in that in the composite material, the carboxyl groups around the graphene oxide interact with the nylon chains, thereby enhancing the mechanical properties of the composite material.

[0073] like Figures 10 to 13 As shown, in step S3, in order to ensure that the graphene oxide does not overlap with each other in nylon, finite element models of graphene oxide / nylon composite materials with graphene oxide volume fractions of 1%, 5%, 10%, 15% and 20% are established for numerical simulation. Through calculation of the finite element model, when the volume fraction of graphene oxide is 20%, the mass fraction of graphene oxide is 1.0699%, and the mechanical properties of the finite element model of the graphene oxide / nylon composite material are optimal and the equivalent elastic modulus is maximum. Figure 10 It represents the process of establishing the finite element model, realizing cross-scale numerical simulation, from nanometer-level calculation to micrometer-level calculation, which will correspond to the actual macroscopic situation. Figure 10 The cross-scale model of graphene oxide / nylon composite materials refers to the realization of cross-scale numerical simulation from nanometer-level calculation to micrometer-level calculation by randomly distributing the geometric dimensions of the molecular dynamics model in the nylon matrix and assigning the mechanical parameters calculated in the molecular dynamics to the corresponding model.

[0074] In step S5, the parameters input into the self-consistent theory model, the Mori-Tanaka model, and the Double-Inclusion model are: the elastic tensors of the inclusion and matrix, and the volume fraction of the inclusion; the parameters input into the Halpin-Tsai model are: the elastic modulus of the inclusion and matrix, and the volume fraction of the inclusion.

[0075] like Figure 14 As shown in the figure, by comparing the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, it is found that the four theoretical models are comprehensively evaluated, and the evaluation formula is defined as:

[0076]

[0077]

[0078]

[0079] In the formula, e is the evaluation factor of the model, E t is the result of the theoretical model, E e is the finite element model result, E m is the molecular dynamics model result, e1 is the percentage compared with the finite element result, and e2 is the percentage compared with the molecular dynamics result.

[0080] By comparison, it can be found that the DI model has a smaller error and the smallest evaluation factor for analyzing the mechanical properties of graphene oxide / nylon composites. The DI model can be used to effectively analyze the mechanical properties of graphene oxide / nylon composites.

[0081] The Double-Inclusion model has a small error in analyzing the mechanical properties of graphene oxide / nylon composites and can effectively analyze the mechanical properties of graphene oxide / nylon composites. The specific calculation is based on the following formula:

[0082]

[0083] φ Ω =[(C B -C Ω ) -1 :C B -S Ω ] -1

[0084] φ R =[(C B -C R ) -1 :C B -S R ] -1

[0085] where φ = f Ω φ Ω +f R φ R , f Ω =Ω / B, f R =R / B; the model is a linear elastic two-phase composite material consisting of inclusion Ω and matrix B, is the equivalent elastic tensor of the composite material, C Ω and C B are the elastic tensors of inclusion and matrix respectively, S is the Eshelby tensor of inclusion, I is the unit tensor; R is the error between inclusion and matrix.

[0086] The mechanical properties of the uniaxial tension process were numerically simulated in molecular dynamics. As the height, width and length of the model increased, the elastic modulus of the composite material first increased and then decreased. Analysis showed that the model with a length, width and height of 3.91172nm, 3.9117nm and 6.96478nm respectively had the best mechanical properties. The mass fraction of graphene oxide was 5.3495%, which effectively improved the elastic modulus of the composite material by 44%.

[0087] Through calculation of the finite element model, when the volume fraction of graphene oxide is 20%, the mass fraction of graphene oxide is 1.0699%, and the mechanical properties of the composite material are the best.

[0088] The results show that the Double-Inclusion model has a small error in analyzing the mechanical properties of graphene oxide / nylon composites and can effectively analyze the mechanical properties of graphene oxide / nylon composites. The accuracy of the finite element model and molecular dynamics model was also verified through theoretical calculations.

[0089] The foregoing description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed herein should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A multi-scale simulation analysis method for graphene oxide reinforced nylon composite materials, characterized in that: The following steps are involved: S1: Construct a molecular dynamics model of graphene oxide / nylon composites, where nylon is selected as the matrix and graphene oxide as the inclusion. The volume fraction of the inclusion is changed to generate multiple molecular dynamics models of the graphene oxide / nylon composites. S2: Simulate the motion of graphene oxide / nylon composites at the microscopic level to determine the molecular dynamics model of graphene oxide / nylon composites with optimal mechanical properties and the volume fraction of graphene oxide under this model; S3: constructing a finite element model of a graphene oxide / nylon composite material, wherein nylon is selected as a matrix, a composite material in an optimal molecular dynamics model of the graphene oxide / nylon composite material is selected as an inclusion, and the volume fraction of the inclusion is changed to generate multiple finite element models of the graphene oxide / nylon composite material; S4: Based on the simulation results of the finite element model, determine the finite element model of the graphene oxide / nylon composite material with the best mechanical properties and the largest equivalent elastic modulus and the volume fraction of graphene oxide under this model; S5: The mechanical properties of inclusions and matrix, and the volume fraction of inclusions in the optimal molecular dynamics model of graphene oxide / nylon composite materials are brought into the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, and compared and mutually verified with the optimal molecular dynamics model of graphene oxide / nylon composite materials; the mechanical properties of inclusions and matrix in the optimal molecular dynamics model of graphene oxide / nylon composite materials and the volume fraction of inclusions in the optimal finite element model of graphene oxide / nylon composite materials are brought into the self-consistent theoretical model, Mori-Tanaka model, Double-Inclusion model, and Halpin-Tsai model, and compared and mutually verified with the optimal finite element model of graphene oxide / nylon composite materials; the optimal theoretical model suitable for characterizing the mechanical properties of graphene oxide / nylon composite materials is obtained.

2. The method for analyzing a multi-scale simulated graphene oxide reinforced nylon composite material according to claim 1, wherein: In step S1, the edges of the graphene sheets of graphene oxide are oxidized to carboxyl groups and combined with nylon. Nylon is a nylon chain polymerized from nylon monomers. Molecular dynamics models of nylon mixed with 2 chains, 4 chains, 6 chains, 8 chains, 10 chains, 12 chains, 14 chains, and 16 chains are established, and a molecular dynamics model of the graphene oxide / nylon composite material is constructed together with the molecular dynamics model of graphene oxide.

3. The method for analyzing a multi-scale simulation of graphene oxide reinforced nylon composite material according to claim 2, wherein: In step S2, LAMMPS is used to simulate the mechanical behavior and interactions of the composite material at the atomic scale. The molecular dynamics simulation includes LAMMPS selection of the force field, setting of the step size, selection of the boundary conditions, setting of the energy minimization, relaxation mode and time, and setting of the uniaxial stretching parameters.

4. The method for analyzing multi-scale simulation of graphene oxide reinforced nylon composite materials according to claim 3, wherein: The initial time step of the molecular dynamics model of the graphene oxide / nylon composite material was set to 0.05 fs, periodic boundary conditions were set, and the conjugate gradient method was selected during the energy minimization process. The relaxation mode, time, and uniaxial stretching steps included: T1: During the relaxation process, the model is first relaxed for 1000 fs at 100 K in the NVT ensemble, and then relaxed for 1000 fs in the NPT ensemble. T2: Change the temperature to 300 K, relax for 1000 fs, then relax for 1000 fs in the NVT ensemble, then gradually increase the temperature to 500 K over 1000 fs, and relax for another 1000 fs; T3: Lower the model temperature from 500K to 300K within 1000fs, and then relax for another 1000fs; T4: At a temperature of 100 K, the NPT ensemble was selected, and the relaxation time was 25000 fs. Finally, the NVT ensemble was relaxed for 250 fs, and then uniaxial stretching was performed.

5. The method for analyzing multi-scale simulated graphene oxide reinforced nylon composite materials according to claim 4, wherein: In the molecular dynamics model of graphene oxide / nylon composite materials, the expression for the measure of the elastic modulus ξ of graphene oxide reinforced nylon is: Where ξ is a measure of the elastic modulus of graphene oxide reinforced nylon; E(PA) is the elastic modulus of nylon; and E(k) is the elastic modulus of the composite material. This allows the molecular dynamics model of the graphene oxide / nylon composite material with optimal mechanical properties to be determined.

6. The method for analyzing multi-scale simulation of graphene oxide reinforced nylon composite materials according to claim 5, characterized in that: The method for selecting the optimal size of the molecular dynamics model of the graphene oxide / nylon composite material is as follows: the size of the molecular dynamics model of the graphene oxide / nylon composite material in the xy direction is given in advance, n molecular dynamics models of the graphene oxide / nylon composite material are established along the z direction of the molecular dynamics model of the graphene oxide / nylon composite material, the molecular dynamics model of the graphene oxide / nylon composite material when the mechanical properties of the composite material along the z direction are optimal is found, and the size of the model in the z direction is recorded as zl; while keeping the height of the molecular dynamics model of the graphene oxide / nylon composite material in the z direction as zl, the size in the xy direction is changed, and m molecular dynamics models of the graphene oxide / nylon composite material are established along the xy plane of the molecular dynamics model of the graphene oxide / nylon composite material, the molecular dynamics model of the graphene oxide / nylon composite material when the mechanical properties of the composite material along the xy plane are optimal is found, and the xy sizes of the models are recorded as xl and yl, where xl, yl, and zl are the optimal sizes of the molecular dynamics model of the graphene oxide / nylon composite material to be established.

7. The method for analyzing multi-scale simulated graphene oxide reinforced nylon composite materials according to claim 6, characterized in that: In step S3, to ensure that the graphene oxide does not overlap with each other in nylon, finite element models of graphene oxide / nylon composite materials with graphene oxide volume fractions of 1%, 5%, 10%, 15% and 20% are established for numerical simulation. By calculating the finite element model, the finite element model of the graphene oxide / nylon composite material with the best mechanical properties and the largest equivalent elastic modulus and the volume fraction of graphene oxide under the model are determined.

8. The method for analyzing multi-scale simulated graphene oxide reinforced nylon composite materials according to claim 7, wherein: In step S5, the parameters input into the self-consistent theory model, the Mori-Tanaka model, and the Double-Inclusion model are: the elastic tensors of the inclusion and matrix, and the volume fraction of the inclusion; the parameters input into the Halpin-Tsai model are: the elastic modulus of the inclusion and matrix, and the volume fraction of the inclusion.

9. The method for analyzing multi-scale simulated graphene oxide reinforced nylon composite materials according to claim 8, characterized in that: A comprehensive evaluation is conducted on four theoretical models: the self-consistent theoretical model, the Mori-Tanaka model, the Double-Inclusion model, and the Halpin-Tsai model. The evaluation formula is defined as: In the formula, e is the evaluation factor of the model, E t is the result of the theoretical model, E e is the finite element model result, E m is the molecular dynamics model result, e1 is the percentage compared with the finite element result, and e2 is the percentage compared with the molecular dynamics result.

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