Material mechanical property full-coupling multi-scale simulation method with molecular scale precision

Abstract

The invention relates to the field of novel material research and development, in particular to a material mechanical property full-coupling multi-scale simulation method with molecular scale precision, which comprises the following steps: establishing a material macroscopic numerical geometric model based on a material macroscopic mechanical physical experiment sample, and establishing a material macroscopic numerical geometric model based on a macroscopic numerical simulation method. Grid division is carried out on the calculation unit comprising the Gaussian points; establishing a microscopic molecular group characterization unit based on a material chemical molecular formula and a molecular structure; establishing association between physical and mechanical properties of molecular group characterization units and stress-strain responses of Gaussian points of macroscopic units, and materializing the Gaussian points to form a multi-scale model; boundary conditions are applied, unit strain is solved, the unit strain is applied to a molecular group characterization unit, mechanical response is expressed through the molecular group characterization unit, and a mechanical equilibrium equation is solved; and obtaining macroscopic parameters of the material according to a multi-scale simulation result. The method provides an effective simulation and prediction means for high-performance material design based on molecular hierarchy.

Description

Technical Field

[0001] The present invention relates to the field of new material research and development, and specifically to a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy. Background Art

[0002] The research and development of new materials is one of the key driving forces of modern scientific and technological progress. However, the traditional trial-and-error method still dominates the material research and development process, which not only leads to high research and development costs, but also prolongs the research and development cycle. The mechanical properties of materials, including hardness, toughness, elastic modulus, etc., are one of the most critical properties in materials science. These properties are closely related to the composition, microstructure and preparation method of the material.

[0003] First of all, the composition of the material is the basis for determining its mechanical properties. Different elements and compounds, due to the different properties of their atomic structure and chemical bonds, will give the material different physical and chemical properties. For example, the element carbon can form two completely different allotropes, graphite and diamond, and their mechanical properties are also very different: graphite is soft and slippery, while diamond is the hardest substance in nature.

[0004] Secondly, the material preparation method also has a profound impact on the mechanical properties. Traditional methods such as casting, forging, rolling, as well as modern technologies such as powder metallurgy, chemical vapor deposition, and 3D printing will change the microstructure of the material to varying degrees, thereby affecting its macroscopic mechanical properties. For example, by controlling the cooling rate, the grain size of the metal can be adjusted, thereby affecting its strength and toughness.

[0005] However, the research and development of new materials still faces a major challenge: the lack of precise quantitative description between molecular structure and macroscopic mechanical properties. This is mainly because the microstructure of the material is extremely complex, and the multi-scale characteristics from atomic scale to macroscopic scale are difficult to fully capture and describe using traditional experimental methods. This requires us to develop new theories and computational methods to achieve a seamless connection from molecular scale to macroscopic scale.

[0006] The development of multi-scale simulation methods has made it possible to solve this problem. Through computational chemistry, molecular dynamics simulation, finite element analysis and other means, we can simulate the structure and behavior of materials at the atomic and molecular levels, and then predict their mechanical properties at the macroscopic scale. However, the above methods are limited to a single scale. The small-scale simulation method only provides mechanical parameters for the large-scale simulation, while ignoring the strong coupling relationship between different scales, and cannot accurately describe the mechanical behavior of the material.

[0007] In summary, the research and development of new materials still continues the traditional trial and error method, facing difficulties such as high cost and long cycle. Generally speaking, the mechanical properties of materials are related to the composition and preparation method of the materials. Fundamentally speaking, the material structures formed by different material components and different preparation methods are often very different. From the perspective of condensed matter physics, its molecular structure is controlled by the material composition and preparation method, and determines the macroscopic mechanical properties of the material. The key reason why the research and development of new materials cannot adopt a bottom-up approach at present is the lack of an accurate quantitative description of molecular structure-macroscopic mechanical properties. Therefore, it is necessary to establish a multi-scale simulation method that can connect the molecular scale and the macroscopic scale. Summary of the invention

[0008] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a fully coupled multi-scale simulation method of the mechanical properties of materials with molecular-scale accuracy. The material is directly designed through chemical composition, and a numerical model is established to simulate the mechanical behavior of the material, thereby truly reflecting the microscopic mechanical response of the material and greatly reducing the computational complexity of molecular material simulation.

[0009] According to one aspect of the present invention, a method for fully coupled multi-scale simulation of mechanical properties of materials with molecular scale accuracy is provided, comprising:

[0010] Based on the macroscopic mechanical and physical experimental samples of materials, a macroscopic numerical geometric model of materials is established, and based on the macroscopic numerical simulation method, the calculation units including Gaussian points are meshed;

[0011] Based on the chemical molecular formula of the material, the molecular cluster characterization unit is established in combination with the molecular structure;

[0012] Establish the relationship between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model;

[0013] Apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material;

[0014] According to the multi-scale simulation results, the macroscopic parameters of the material are obtained.

[0015] As a further technical solution, the macroscopic numerical simulation method includes but is not limited to the material point method, the smooth particle method or the finite element method.

[0016] As a further technical solution, the computing unit grid is divided into nodes, and the control equation of the material is solved based on the nodes. The control equation of the material includes a mass conservation equation and a momentum conservation equation. The functional relationship expression of the mass conservation equation and the momentum conservation equation is as follows:

[0017] (1);

[0018] (2);

[0019] in, is the density of the material, is the object speed, is the stress tensor, For physical strength; is the gradient operator.

[0020] As a further technical solution, when the grid is divided into calculation units, Gaussian point information is extracted for unit stress integration, and the unit stress is integrated into the node force through the basis function. The functional relationship expression of the node force is as follows:

[0021] (3);

[0022] in, is the nodal force, p is the material point, is the computational domain, is the basis function value of the Gaussian point at node I, is the stress tensor.

[0023] As a further technical solution, the functional relationship expression of the stress-strain response of the macroscopic unit Gaussian point of the molecular cluster characterization unit is:

[0024] (4);

[0025] in, is the mass of atom i, is the spatial coordinate, is the velocity of the corresponding atom, is the unit volume, and W is the Virial term.

[0026] As a further technical solution, the multi-scale simulation method further includes:

[0027] After the macroscopic deformation field is applied, the unit nodes are displaced, forming unit strain;

[0028] The unit strain acts on the molecular cluster characterization unit, the molecules in the unit are rearranged, the intermolecular forces change, and a macroscopic stress response is caused;

[0029] The stress response is then mapped to the macroelements and integrated to the nodal forces;

[0030] Solve the equilibrium equation and adjust the node displacement until the molecules of the molecular cluster representation unit collectively enter the equilibrium state.

[0031] As a further technical solution, the unit strain acts on the molecular cluster characterization unit, including:

[0032] Molecular dynamics is used to simulate the molecular cluster characterization unit. First, the entire molecular cluster characterization unit is affine deformed, and the molecules of the molecular cluster characterization unit are collectively moved to the equilibrium point in the current state through the conjugate gradient descent method. The stress tensor is calculated according to the functional relationship expression of the stress-strain response of the Gaussian point of the macro unit.

[0033] According to one aspect of the present invention, a fully coupled multi-scale simulation system for mechanical properties of materials with molecular scale accuracy is provided, comprising:

[0034] The first main module is used to establish a macroscopic numerical geometric model of the material based on the macroscopic mechanical and physical experimental samples of the material, and to mesh the calculation units including Gaussian points;

[0035] The second main module is used to establish a microscopic molecular cluster characterization unit based on the material chemical molecular formula and combined with the molecular structure;

[0036] The third main module is used to establish the association between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model;

[0037] The fourth main module is used to apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply the unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express the mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material;

[0038] The fifth main module is used to obtain the macroscopic parameters of the material based on the multi-scale simulation results.

[0039] According to one aspect of the present invention, there is provided a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the steps of a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy.

[0040] According to one aspect of the present specification, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores computer instructions, wherein the computer instructions enable the computer to execute the steps of a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention can simulate the material test loading process by adopting a fully coupled simulation method, obtain the mechanical properties of the material such as material strength and stiffness, provide an effective simulation and prediction method for the design of high-performance materials based on the molecular level, and greatly reduce the material research and development design cost and experimental cycle.

[0043] 2. The present invention provides a fully coupled multi-scale simulation method for the mechanical properties of materials with molecular-scale accuracy. This method can directly consider the molecular-level dynamic behavior of materials and reflect the influence of intermolecular forces on the macroscopic material properties.

[0044] 3. The multi-scale numerical simulation method provided by the present invention can directly support the design of materials from the molecular level, greatly reducing the material research and development design costs and experimental cycle.

[0045] 4. The multi-scale numerical simulation method designed in the present invention adopts a macro-micro direct coupling method, which can greatly reduce the amount of calculation required for molecular motion simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are 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.

[0047] Figure 1 A schematic flow chart of a method for fully coupled multi-scale simulation of material mechanical properties with molecular-scale accuracy provided in an embodiment of the present invention.

[0048] Figure 2 A schematic diagram of a multi-scale numerical model generation method for a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy provided in an embodiment of the present invention.

[0049] Figure 3 A schematic diagram of a method for generating a molecular cluster characterization unit for a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy provided in an embodiment of the present invention.

[0050] Figure 4 A schematic diagram of a conjugate gradient descent method for solving a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy provided in an embodiment of the present invention.

[0051] Figure 5A schematic diagram of the analysis of multi-scale numerical model results of a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy provided in an embodiment of the present invention.

[0052] Figure 6 Schematic diagram of the system structure of a fully coupled multi-scale simulation system of material mechanical properties with molecular-scale accuracy provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, for example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in 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. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0055] The embodiment of the present invention provides a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy, comprising the following steps:

[0056] Step 1: Based on the macroscopic mechanical and physical experimental samples of the material, a macroscopic numerical geometric model of the material is established, and based on the macroscopic numerical simulation method, the calculation unit including the Gaussian point is meshed;

[0057] Step 2: Based on the chemical molecular formula of the material and combined with the molecular structure, a microscopic molecular cluster characterization unit is established;

[0058] Step 3, establish the association between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model;

[0059] Step 4: Conduct multi-scale simulation:

[0060] Apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material;

[0061] Step 5, obtaining macroscopic parameters of the material according to the multi-scale simulation results, wherein the macroscopic parameters include one or more of elastic modulus, tensile strength, fracture toughness, indentation hardness and Poisson's ratio.

[0062] In step 1, a macroscopic numerical geometric model of the material is established based on the macroscopic mechanical and physical experimental samples of the material, including: establishing a geometric model according to the sample size and shape of the material design and test experiment.

[0063] Macroscopic mechanical and physical experiments on materials include but are not limited to uniaxial compression, triaxial tests, shear tests, nanoindentation and other material parameter testing experiments.

[0064] Macro numerical simulation methods include, but are not limited to, material point method, smoothed particle method or finite element method. These algorithms can be coupled at the macro level and all require Gaussian points for stress integration. When the two methods are coupled, each Gaussian point can be simulated using molecular cluster characterization units.

[0065] The macroscopic numerical simulation method involved in the present invention may also have the following characteristics:

[0066] The computational unit grid is divided into nodes, and the material control equations are solved based on the nodes. The material control equations include the mass conservation equation and the momentum conservation equation. The functional relationship between the mass conservation equation and the momentum conservation equation is as follows:

[0067] (1);

[0068] (2);

[0069] in, is the density of the material, is the object speed, is the stress tensor, For physical strength; is the gradient operator.

[0070] When meshing the calculation unit, the Gauss point information is extracted for unit stress integration. The unit stress is integrated into the node force through the basis function. The functional relationship expression of the node force is as follows:

[0071] (3);

[0072] in, is the nodal force, p is the material point, is the computational domain, is the basis function value of the Gaussian point at node I, is the stress tensor.

[0073] The molecular level numerical simulation method involved in the present invention may also have the following characteristics:

[0074] In step 2, the molecular characterization unit has different strategies for generating its molecular structure according to the type of material. First, the ratio of different chemical elements in the molecular characterization unit can be determined according to the chemical composition of the material;

[0075] Secondly, if the material is a crystalline material, then its molecular structure is regular and presents a periodic distribution. Then we can directly generate a periodically distributed crystal molecular structure based on the crystal constants measured experimentally.

[0076] If the material is an amorphous material, it cannot be directly generated according to the above method, so the corresponding molecular structure is generated according to the material preparation process. For example, for glass materials, in practice we use the melting-cooling-quenching process to prepare glass, so the melting-cooling-quenching process is simulated by molecular dynamics to form the required molecular structure; if the material is an amorphous gel material, then the corresponding molecular structure is formed by simulating the deposition-agglomeration process of the gel material. Among them, the most representative simulation method is the non-canonical system Monte Carlo method.

[0077] Molecular characterization units all use periodic boundaries. Periodic boundaries are a solution for processing boundaries in order to avoid unrealistic interface effects during molecular dynamics simulations.

[0078] The molecular cluster and macro unit association method involved in the present invention may also have the following characteristics:

[0079] In step 3, the Gaussian stress-strain response of the macro-unit of the molecular cluster characterization unit is derived by statistical mechanics:

[0080] (4);

[0081] in, is the mass of atom i, is the spatial coordinate, is the velocity of the corresponding atom, is the unit volume, W is the Virial term; , are spatial coordinates (x, y, z), Respectively represented as velocity vector exist or The velocity component in the direction, It can be =x, it can be =y, and it can be =z.

[0082] The multi-scale numerical simulation method involved in the present invention may also have the following characteristics:

[0083] Step 1: After applying the macroscopic deformation field, the unit nodes are displaced to form unit strain;

[0084] Step 2: The unit strain acts on the molecular cluster characterization unit, the molecules in the unit are rearranged, the intermolecular forces change, and a macroscopic stress response is caused;

[0085] Step 3, the stress response is then mapped to the macro-elements and integrated into the nodal forces;

[0086] Step 4, solve the equilibrium equation and adjust the node displacement until the molecules of the molecular cluster characterization unit collectively enter the equilibrium state.

[0087] The molecular cluster characterization unit simulation involved in the multi-scale numerical simulation method of the present invention may also have the following characteristics:

[0088] The unit strain acts on the molecular cluster characterization unit, including: using molecular dynamics to simulate the molecular dynamic process inside the molecular cluster characterization unit, first performing affine deformation on the entire molecular cluster characterization unit, and then moving the molecules of the molecular cluster characterization unit collectively to the equilibrium point in the current state by the conjugate gradient descent method, and calculating the stress tensor according to formula (4).

[0089] In affine transformation, the new coordinates ( ) is determined by the initial coordinates ( ) is generated by the following translation, rotation and uniform deformation changes:

[0090] ;

[0091] ;

[0092] ;

[0093] Among them, a, b, and c are the new coordinate axes x after deformation. new The projection coefficients on the three axes of the old coordinate axis before deformation. Similarly, d, e, f and h, i, j are y new and z new The corresponding projection coefficients, k, l, and m, are the three translation components of the coordinate center.

[0094] like Figure 1As shown, the present invention involves a fully coupled multi-scale simulation method of material mechanical properties with molecular-level accuracy, including macroscopic material geometry modeling and meshing; establishing a microscopic molecular cluster characterization unit based on the material chemical formula in combination with the molecular structure; combining the macro-micro model to materialize the Gaussian points and form a multi-scale model; applying boundary conditions, solving the unit macroscopic strain and mapping it to the microscopic molecular cluster characterization unit, obtaining the macroscopic stress, and returning to the macroscopic model to solve the equilibrium equation; finally, conducting macro-micro analysis to obtain the mechanical properties and microscopic response of the material.

[0095] like Figure 2 As shown, the multi-scale numerical model generation method involved in the present invention includes two parts: macroscopic and microscopic.

[0096] Firstly, according to the microscope uniaxial compression test sample, the macroscopic numerical experimental model is designed and the geometric model is established. The sample size is selected as a Φ1.5×3.0mm cylinder, and the grid is divided to establish the macroscopic model. Figure 2 As shown in Figure 21.

[0097] Then, at the microscopic level, a molecular cluster characterization unit is established based on the chemical molecular formula and molecular structure characteristics of the material. The embodiment selects a molecular cluster with a chemical molecular formula of The metallic glass material has an amorphous structure, and the generated multiple molecular cluster characterization units are as follows Figure 2 As shown in Figure 22.

[0098] Finally, the generated molecular cluster characterization units of multiple different configurations are associated with the Gaussian points of the macroscopic model to form a multi-scale model.

[0099] like Figure 3 As shown, the metallic glass material molecular cluster unit involved in the present invention adopts the GCMC generation algorithm, including random generation of molecular coordinates based on Monte Carlo; random trial displacement of molecules; calculation of the energy of the system in the current state, and determination of whether to accept the particle generation based on the initial energy; and repeating the above steps until the set target density is reached.

[0100] like Figure 4 As shown, the conjugate gradient descent algorithm process involved in the present invention includes reading the interaction potential and molecular topology; assigning the initial position and velocity and calculating the corresponding energy gradient search direction; finding the optimal step length along the current search direction; calculating the conjugate parameter; and updating the search direction in combination with the conjugate parameter. Repeat the above steps until the new energy gradient is less than the set threshold.

[0101] like Figure 5 As shown, the multi-scale simulation method of the present invention applies load to the model, adopts displacement control loading, and the loading rate is 0.01μs -1, the macroscopic deformation of the material was obtained51, and the stress response of the molecular cluster characterization unit was simulated at the same time, and the molecular cluster microscopic evolution characteristics were obtained by solving equation (4)52. The material showed a band-like failure that penetrated the specimen at the macroscopic level. The molecular cluster characterization unit inside was analyzed and its local strain characteristics were statistically analyzed. It was found that the molecular cluster showed local band-like failure characteristics at the microscopic level, which led to the macroscopic bearing failure of the unit.

[0102] The implementation basis of each embodiment of the present invention is to implement programmed processing through a device with a processor function. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present invention are encapsulated into various modules. Based on this reality, on the basis of the above embodiments, an embodiment of the present invention provides a fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy, which is used to execute a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy in the above method embodiment.

[0103] See also Figure 6 The system includes: a first main module, which is used to establish a macroscopic numerical geometric model of the material based on the macroscopic mechanical physical experimental sample of the material, and to mesh the calculation unit including the Gaussian point; a second main module, which is used to establish a microscopic molecular cluster characterization unit based on the chemical molecular formula of the material and in combination with the molecular structure; a third main module, which is used to establish the association between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the macroscopic unit Gaussian point, materialize the Gaussian point, and form a multi-scale model; a fourth main module, which is used to apply boundary conditions, calculate the unit strain according to the macroscopic deformation of the material, apply the unit strain to the molecular cluster characterization unit, use molecular dynamics for simulation, express the mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material; a fifth main module, which is used to obtain the macroscopic parameters of the material according to the multi-scale simulation results.

[0104] The fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy provided by the embodiment of the present invention adopts Figure 6 Several modules in it directly design materials through chemical composition, establish numerical models to simulate the mechanical behavior of materials, truly reflect the microscopic mechanical response of materials, and greatly reduce the computational complexity of molecular material simulation.

[0105] It should be noted that the system embodiment provided by the present invention is used to implement the methods in the above method embodiment as well as the methods in other method embodiments provided by the present invention. The only difference is that the corresponding functional modules are set. The principle is basically the same as the principle of the above system embodiment provided by the present invention. As long as the technical personnel in this field refer to the specific technical solutions in other method embodiments on the basis of the above system embodiment, obtain the corresponding technical means and the technical solutions composed of these technical means by combining the technical features, and on the premise of ensuring the practicality of the technical solutions, improve the modules in the above system embodiment to obtain the corresponding system class embodiments, which are used to implement the methods in other method class embodiments. For example:

[0106] Based on the contents of the above system embodiments, as a preferred embodiment, the fully coupled multi-scale simulation system of material mechanical properties with molecular-scale accuracy provided in the embodiments of the present invention, the macroscopic numerical simulation methods include but are not limited to the material point method, the smooth particle method or the finite element method.

[0107] Based on the content of the above system embodiment, as a preferred embodiment, the fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy provided in the embodiment of the present invention divides the computing unit grid into nodes, and solves the control equation of the material based on the nodes. The control equation of the material includes the mass conservation equation and the momentum conservation equation. The functional relationship expression of the mass conservation equation and the momentum conservation equation is as follows:

[0108] (1);

[0109] (2);

[0110] in, is the density of the material, is the object speed, is the stress tensor, For physical strength; is the gradient operator.

[0111] Based on the content of the above system embodiment, as a preferred embodiment, in the fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy provided in the embodiment of the present invention, when the grid is divided into calculation units, Gaussian point information is extracted for unit stress integration, and the unit stress is integrated into the node force through the basis function. The functional relationship expression of the node force is as follows:

[0112] (3);

[0113] in, is the nodal force, p is the material point, is the computational domain, is the basis function value of the Gaussian point at node I, is the stress tensor.

[0114] Based on the content of the above system embodiment, as a preferred embodiment, in the fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy provided in the embodiment of the present invention, the functional relationship expression of the macro unit Gaussian point stress-strain response of the molecular cluster characterization unit is:

[0115] (4);

[0116] in, is the mass of atom i, is the spatial coordinate, is the velocity of the corresponding atom, is the unit volume, and W is the Virial term.

[0117] Based on the contents of the above system embodiment, as a preferred embodiment, in the fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy provided in the embodiment of the present invention, carrying out multi-scale simulation also includes:

[0118] After the macroscopic deformation field is applied, the unit nodes are displaced, forming unit strain;

[0119] The unit strain acts on the molecular cluster characterization unit, the molecules in the unit are rearranged, the intermolecular forces change, and a macroscopic stress response is caused;

[0120] The stress response is then mapped to the macroelements and integrated to the nodal forces;

[0121] Solve the equilibrium equation and adjust the node displacement until the molecules of the molecular cluster representation unit collectively enter the equilibrium state.

[0122] Based on the contents of the above system embodiment, as a preferred embodiment, in the fully coupled multi-scale simulation system of material mechanical properties with molecular scale accuracy provided in the embodiment of the present invention, the unit strain acts on the molecular cluster characterization unit, including:

[0123] Molecular dynamics simulation is used to first perform affine deformation on the entire molecular cluster characterization unit, and then the molecules of the molecular cluster characterization unit are collectively moved to the equilibrium point in the current state through the conjugate gradient descent method, and the stress tensor is calculated according to the functional relationship expression of the stress-strain response of the Gaussian point of the macro unit.

[0124] Based on the same inventive concept as the above-mentioned embodiment, the embodiment of the present invention further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy are implemented as follows:

[0125] Based on the macroscopic mechanical and physical experimental samples of materials, a macroscopic numerical geometric model of materials is established, and based on the macroscopic numerical simulation method, the calculation units including Gaussian points are meshed;

[0126] Based on the chemical molecular formula of the material, the molecular cluster characterization unit is established in combination with the molecular structure;

[0127] Establish the relationship between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model;

[0128] Apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material;

[0129] According to the multi-scale simulation results, the macroscopic parameters of the material are obtained.

[0130] Based on the same inventive concept as the above-mentioned embodiment, the embodiment of the present invention further provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions enable the computer to execute the steps of a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy, as shown below:

[0131] Based on the macroscopic mechanical and physical experimental samples of materials, a macroscopic numerical geometric model of materials is established, and based on the macroscopic numerical simulation method, the calculation units including Gaussian points are meshed;

[0132] Based on the chemical molecular formula of the material, the molecular cluster characterization unit is established in combination with the molecular structure;

[0133] Establish the relationship between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model;

[0134] Apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material;

[0135] According to the multi-scale simulation results, the macroscopic parameters of the material are obtained.

[0136] In summary, the present invention performs numerical geometric modeling based on macroscopic experimental samples of materials, divides grid units and extracts Gaussian point information; establishes molecular cluster characterization units according to the chemical molecular formula and molecular structure of the material; materializes Gaussian points through molecular cluster characterization units, and associates the mechanical state of Gaussian points of grid units with the statistical mechanical characteristics of molecular clusters; applies boundary conditions for iterative simulation, calculates strain according to the macroscopic deformation of the material, applies it to the molecular cluster characterization unit, and after molecular-level calculation, statistically calculates the microscopic mechanical properties of the molecular cluster characterization unit and feeds back as the macroscopic stress of the material to solve the mechanical equilibrium equation; through the above process, the material experimental loading process can be simulated to obtain macroscopic parameter information such as material strength and stiffness. This method provides an effective simulation and prediction method for the design of high-performance materials based on the molecular level, greatly reducing the cost of material research and development design and the experimental cycle.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A fully coupled multi-scale simulation method for material mechanical properties with molecular scale accuracy, characterized in that: The following steps are involved: Based on the macroscopic mechanical and physical experimental samples of materials, a macroscopic numerical geometric model of materials is established, and based on the macroscopic numerical simulation method, the calculation units including Gaussian points are meshed; Based on the chemical molecular formula of the material, the molecular cluster characterization unit is established in combination with the molecular structure; Establish the relationship between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model; Apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material; According to the multi-scale simulation results, the macroscopic parameters of the material are obtained.

2. According to claim 1, a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy is characterized in that: The macroscopic numerical simulation method includes but is not limited to the material point method, the smooth particle method or the finite element method.

3. According to claim 1, a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy is characterized in that: The computing unit grid is divided into nodes, and the control equation of the material is solved based on the nodes. The control equation of the material includes a mass conservation equation and a momentum conservation equation. The functional relationship expression of the mass conservation equation and the momentum conservation equation is as follows: （1）； （2）； in, is the material density, t is the time, is the object speed, is the stress tensor, For physical strength; is the gradient operator.

4. According to claim 3, a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy is characterized in that: When meshing the calculation unit, the Gauss point information is extracted for unit stress integration. The unit stress is integrated into the node force through the basis function. The functional relationship expression of the node force is as follows: （3）； in, is the nodal force, p is the material point, is the computational domain, is the basis function value of the Gaussian point at node I, is the stress tensor.

5. According to claim 1, a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy is characterized in that: The functional relationship expression of the stress-strain response of the macro-unit Gaussian point of the molecular cluster characterization unit is as follows: （4）； in, is the mass of atom i, is the spatial coordinate, is the velocity of the corresponding atom, is the unit volume, and W is the Virial term.

6. A fully coupled multi-scale simulation method for material mechanical properties with molecular scale accuracy according to claim 4, characterized in that: The multi-scale simulation method further comprises: After the macroscopic deformation field is applied, the unit nodes are displaced, forming unit strain; The unit strain acts on the molecular cluster characterization unit, the molecules in the unit are rearranged, the intermolecular forces change, and a macroscopic stress response is caused; The stress response is then mapped to the macroelements and integrated to the nodal forces; Solve the equilibrium equation and adjust the node displacement until the molecules of the molecular cluster representation unit collectively enter the equilibrium state.

7. A fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy according to claim 6, characterized in that: The unit strain acts on the molecular cluster characterization unit, including: using molecular dynamics to simulate the molecular dynamic process inside the molecular cluster characterization unit, first performing affine deformation on the entire molecular cluster characterization unit, and collectively moving the molecules of the molecular cluster characterization unit to the equilibrium point in the current state through the conjugate gradient descent method, and calculating the stress tensor according to the functional relationship expression of the stress-strain response of the Gaussian point of the macro unit.

8. A fully coupled multi-scale simulation system for material mechanical properties with molecular scale accuracy, characterized in that: include: The first main module is used to establish a macroscopic numerical geometric model of the material based on the macroscopic mechanical and physical experimental samples of the material, and to mesh the calculation units including Gaussian points; The second main module is used to establish a microscopic molecular cluster characterization unit based on the material chemical molecular formula and combined with the molecular structure; The third main module is used to establish the association between the physical and mechanical properties of the molecular cluster characterization unit and the stress-strain response of the Gaussian point of the macro unit, materialize the Gaussian point, and form a multi-scale model; The fourth main module is used to apply boundary conditions, calculate unit strain according to the macroscopic deformation of the material, apply the unit strain to the molecular cluster characterization unit, use molecular dynamics to simulate, express the mechanical response through the molecular cluster characterization unit, return to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulate the macroscopic deformation of the material; The fifth main module is used to obtain the macroscopic parameters of the material based on the multi-scale simulation results.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a fully coupled multi-scale simulation method of material mechanical properties with molecular scale accuracy as described in any one of claims 1 to 7 are implemented.

10. A non-transitory computer readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores computer instructions, which enable the computer to execute the steps of a fully coupled multi-scale simulation method of material mechanical properties with molecular-scale accuracy as described in any one of claims 1 to 7.

Images