A full-coupled multi-scale simulation method for material mechanical properties with molecular scale precision

Abstract

The application relates to the field of new material research and development, in particular to a material mechanics characteristic full-coupling multi-scale simulation method with molecular scale precision, which comprises the following steps: based on a material macroscopic mechanics physical experiment sample, a material macroscopic numerical geometry model is established, and a calculation unit including a Gaussian point is subjected to grid division based on a macroscopic numerical simulation method; based on a material chemical molecular formula, a micro-molecular group representation unit is established in combination with a molecular structure; the correlation between the physical mechanics characteristics of the molecular group representation unit and the stress and strain response of the macroscopic unit Gaussian point is established, the Gaussian point is solidified, and a multi-scale model is formed; a boundary condition is applied, the unit strain is solved, the unit strain is applied in the molecular group representation unit, the mechanical response is expressed through the molecular group representation unit, and a mechanical equilibrium equation is solved; and the macroscopic parameters of the material are obtained according to the multi-scale simulation result. The method provides an effective simulation prediction means for high-performance material design based on a molecular level.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new material research and development, in particular to a material mechanics property full-coupling multi-scale simulation method with molecular scale precision. BACKGROUND

[0002] The research and development of new materials is one of the key driving forces for modern scientific and technological progress. However, the traditional trial-and-error method still dominates the material 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, and elastic modulus, are among the most critical attributes in materials science. These properties are closely related to the composition, microstructure, and preparation method of the material.

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

[0004] Secondly, the preparation method of the material also has a profound impact on the mechanical properties. Traditional casting, forging, rolling, and other methods, as well as modern powder metallurgy, chemical vapor deposition, 3D printing, and other technologies, 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 current research and development of new materials still faces a major challenge: the lack of a quantitative description between the precise molecular structure and the macroscopic mechanical properties. This is mainly because the microstructure of the material is extremely complex, and the multi-scale characteristics from the atomic scale to the 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 seamless connection from the molecular scale to the macroscopic scale.

[0006] The development of multi-scale simulation methods makes 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 level, and then predict their mechanical properties at the macroscopic scale. However, the above methods are limited to a single scale, and small-scale simulation methods only provide mechanical parameters for large-scale simulation, ignoring the strong coupling between different scales, and cannot accurately describe the mechanical behavior of materials.

[0007] In summary, the development of new materials still continues the traditional trial and error method, and faces difficulties such as high cost and long cycle. Generally speaking, the mechanical properties of materials are related to the composition of materials and the preparation method. Fundamentally, the material structure formed by different material components and different preparation methods is often very different. From the point of view of condensed matter physics, the molecular structure is controlled by the material composition and the preparation method, and determines the macroscopic mechanical properties of the material. The key to the current development of new materials is the lack of quantitative description of the molecular structure-macroscopic mechanical properties. Therefore, it is necessary to establish a multi-scale simulation method that can link the molecular scale and the macroscopic scale. SUMMARY

[0008] In order to overcome the shortcomings of the prior art, the present application provides a material mechanical property full coupling multi-scale simulation method with molecular scale precision, which directly designs the material through chemical composition, establishes a numerical model to simulate the mechanical behavior of the material, and truly reflects the micro-mechanical response of the material, thereby greatly reducing the calculation amount of molecular material simulation.

[0009] According to an aspect of the present application, a material mechanical property full coupling multi-scale simulation method with molecular scale precision is provided, comprising:

[0010] Based on the material macroscopic mechanical physical experiment sample, a material macroscopic numerical geometric model is established, and based on the macroscopic numerical simulation method, the calculation unit including the Gaussian point is meshed;

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

[0012] The correlation between the physical and mechanical properties of the molecular group representation unit and the stress and strain response of the macroscopic unit Gaussian point is established, the Gaussian point is solidified, and a multi-scale model is formed;

[0013] Boundary conditions are applied, the element strain is calculated according to the macroscopic deformation of the material, the element strain is applied in the molecular group representation unit, molecular dynamics is used for simulation, the mechanical response is expressed through the molecular group representation unit, the macroscopic numerical geometric model is returned to solve the mechanical equilibrium equation, and the macroscopic deformation of the material is simulated;

[0014] According to the multi-scale simulation result, 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 calculation unit is meshed to form nodes, and the control equation of the substance is solved based on the nodes, the control equation of the substance includes a mass conservation equation and a momentum conservation equation, and a functional relationship expression of the mass conservation equation and the momentum conservation equation is as follows:

[0017] (1);

[0018] (2);

[0019] wherein, is a substance density, is an object velocity, is a stress tensor, is a substance body force; is a gradient operator.

[0020] As a further technical solution, when the calculation unit is meshed, Gaussian point information is extracted for element stress integration, and the element stress is integrated to the node force through a basis function, and a functional relationship expression of the node force is as follows:

[0021] (3);

[0022] wherein, is a node force, p is a substance point, is a calculation domain, is a basis function value of the Gaussian point at the node I, is a stress tensor.

[0023] As a further technical solution, a functional relationship expression of the macroscopic element Gaussian point stress-strain response of the molecular group representing element is as follows:

[0024] (4);

[0025] wherein, is a mass of an atom i, is a spatial coordinate, is a velocity of a corresponding atom, is a volume representing element, and W is a Virial term.

[0026] As a further technical solution, the multiscale simulation method further includes:

[0027] After a macroscopic deformation field is applied, the element nodes are displaced to form element strain;

[0028] The element strain acts on the molecular group representing element, the molecules in the element are rearranged, the intermolecular force is changed, and a macroscopic stress response is caused;

[0029] The stress response is then mapped to the macroscopic element and integrated to the nodal force;

[0030] The equilibrium equation is solved, the nodal displacement is adjusted, and the molecular collective of the molecular group representation element enters an equilibrium state.

[0031] As a further technical solution, the element strain acts on the molecular group representation element, including:

[0032] The molecular dynamics is used to simulate the molecular group representation element, affine deformation is first performed on the entire molecular group representation element, the molecular collective of the molecular group representation element is moved to an equilibrium point in a current state by using the conjugate gradient descent method, and the stress tensor is calculated according to the function relationship expression of the macroscopic element Gaussian point stress strain response.

[0033] According to an aspect of the present application, a material mechanics characteristic full-coupling multi-scale simulation system with molecular scale precision is provided, including:

[0034] The first main module is used to establish a material macroscopic numerical geometry model based on a material macroscopic mechanics physical experiment sample, and perform grid division on a calculation element including a Gaussian point;

[0035] The second main module is used to establish a microcosmic molecular group representation element based on a material chemical molecular formula and in combination with a molecular structure;

[0036] The third main module is used to establish a correlation between the physical mechanics characteristic of the molecular group representation element and the Gaussian point stress strain response of the macroscopic element, materialize the Gaussian point, and form a multi-scale model;

[0037] The fourth main module is used to apply a boundary condition, obtain an element strain according to a material macroscopic deformation, apply the element strain in the molecular group representation element, simulate by using the molecular dynamics, express a mechanics response through the molecular group representation element, return to the macroscopic numerical geometry model to solve a mechanics equilibrium equation, and simulate a material macroscopic deformation;

[0038] The fifth main module is used to obtain a material macroscopic parameter according to a multi-scale simulation result.

[0039] According to an aspect of the present application, a computer device is provided, including a memory and a processor, the memory stores a computer program, and the processor implements the steps of a material mechanics characteristic full-coupling multi-scale simulation method with molecular scale precision when executing the computer program.

[0040] According to an aspect of the present application, a non-transitory computer readable storage medium is provided, the non-transitory computer readable storage medium stores computer instructions, and the computer instructions make the computer execute the steps of a material mechanics characteristic full-coupling multi-scale simulation method with molecular scale precision.

[0041] Compared with the prior art, the present application has the beneficial effects that:

[0042] 1. The present application can simulate the process of material test loading by adopting full coupling simulation method, obtain the mechanical properties of materials such as material strength and stiffness, and provide effective simulation prediction means for high-performance material design based on molecular level, thereby greatly reducing the material research and development design cost and experimental period.

[0043] 2. The present application provides a material mechanical property full coupling multiscale simulation method with molecular scale precision, which can directly consider the molecular level dynamics behavior of the material and reflect the influence of the intermolecular force of the material on the macroscopic material properties.

[0044] 3. The multiscale numerical simulation method provided by the present application can directly support the design of materials from the molecular level, thereby greatly reducing the material research and development design cost and experimental period.

[0045] 4. The multiscale numerical simulation method designed by the present application adopts a macro-micro direct coupling method, which can greatly reduce the calculation amount required for molecular motion simulation. BRIEF DESCRIPTION OF DRAWINGS

[0046] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0047] Figure 1 A flowchart of a material mechanical property full coupling multiscale simulation method with molecular scale precision provided by the present application.

[0048] Figure 2 A multiscale numerical model generation method schematic diagram of a material mechanical property full coupling multiscale simulation method with molecular scale precision provided by the present application.

[0049] Figure 3 A molecular group representation unit generation method schematic diagram of a material mechanical property full coupling multiscale simulation method with molecular scale precision provided by the present application.

[0050] Figure 4 A conjugate gradient descent method solving schematic diagram of a material mechanical property full coupling multiscale simulation method with molecular scale precision provided by the present application.

[0051] Figure 5A multi-scale numerical model result analysis schematic diagram of a material mechanics characteristic full coupling multi-scale simulation method with molecular scale precision provided for an embodiment of the present application.

[0052] Figure 6 A system structure schematic diagram of a material mechanics characteristic full coupling multi-scale simulation system with molecular scale precision provided for an embodiment of the present application. DETAILED DESCRIPTION

[0053] The terms "comprising" and "having" and any variations thereof in the specification and claims and the above drawings are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or equipment including a series of steps or units, not necessarily limited to which steps or units are clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or equipment.

[0054] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application. In addition, the technical features in each embodiment or single embodiment provided by the present application can be combined with each other to form new technical schemes, and such combination is not restricted by the order of steps and / or structure composition mode, but must be based on the implementation by those skilled in the art, and when the combination of technical schemes appears contradictory or unimplementable, it should be considered that the combination of technical schemes does not exist, and is not within the protection scope required by the present application.

[0055] The embodiments of the present application provide a material mechanics characteristic full coupling multi-scale simulation method with molecular scale precision, which comprises the following steps:

[0056] Step 1, based on a material macroscopic mechanics physical experiment sample, a material macroscopic numerical geometry model is established, and based on a macroscopic numerical simulation method, a calculation unit including a Gaussian point is meshed;

[0057] Step 2, based on a material chemical molecular formula, a micro-molecular group characterization unit is established in combination with a molecular structure;

[0058] Step 3, the correlation between the physical and mechanical characteristics of the molecular group characterization unit and the stress and strain response of the Gaussian point of the macroscopic unit is established, the Gaussian point is solidified, and a multi-scale model is formed;

[0059] Step 4, multi-scale simulation is carried out:

[0060] Applying boundary conditions, obtaining element strain according to macroscopic deformation of the material, applying element strain in the molecular group characterization unit, simulating by molecular dynamics, expressing mechanical response through the molecular group characterization unit, returning to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulating the macroscopic deformation of the material.

[0061] Step 5, obtaining the 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, the material macroscopic numerical geometric model is established based on the material macroscopic mechanics physical experiment sample, including: establishing a geometric model according to the sample size and shape of the material design and test experiment.

[0063] The material macroscopic mechanics physical experiment includes but is not limited to uniaxial compression, triaxial test, shear test, nanoindentation and other material parameter test experiments.

[0064] The macroscopic numerical simulation method includes but is not limited to material point method, smooth particle method or finite element method. These algorithms can be coupled at the macroscopic level, and all need to use Gaussian points for stress integration. When the two methods are coupled, the respective Gaussian points can be simulated by using the molecular group characterization unit.

[0065] The macroscopic numerical simulation method disclosed by the application can also have the following characteristics:

[0066] The grid division forms nodes for the calculation unit, and the control equation of the material is solved based on the nodes, wherein the control equation of the material includes the mass conservation equation and the momentum conservation equation, and the functional relationship expression of the mass conservation equation and the momentum conservation equation is as follows:

[0067] (1);

[0068] (2);

[0069] Wherein, The density of the material is, The velocity of the object is, The stress tensor is, The material body force is; The gradient operator is.

[0070] When the grid division calculation unit is divided, the Gaussian point information is extracted, which is used for element stress integration, and the element stress is integrated to the node force through the basis function, and the functional relationship expression of the node force is as follows:

[0071] (3);

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

[0073] The molecular level numerical simulation method disclosed by the present application can also have the following characteristics:

[0074] In step 2, the strategy for generating the molecular structure of the molecular characterization unit is different according to the type of the material. First, according to the chemical composition of the material, the proportion of different chemical elements in the molecular characterization unit can be determined.

[0075] Secondly, if the material belongs to a crystalline material, the molecular structure of the material is regular and periodically distributed, and then the periodic distribution of the crystalline molecular structure can be directly generated according to the experimentally measured crystal constant.

[0076] If the material belongs to an amorphous material, it cannot be directly generated according to the above method, and then the corresponding molecular structure is generated according to the preparation process of the material. For example, glass material is prepared by the process of melting-cooling-quenching in practice, and then the required molecular structure is formed by simulating the process of melting-cooling-quenching by molecular dynamics simulation. If the material belongs to a gel material, the corresponding molecular structure is formed by simulating the process of deposition-agglomeration of the gel material, and the most representative simulation method is the non-regular system Monte Carlo method.

[0077] The periodic boundary is used in the molecular characterization unit. The periodic boundary is a scheme for processing the boundary in the process of molecular dynamics simulation to avoid the generation of unreal interface effects.

[0078] The molecular group and macro unit association method disclosed by the present application can also have the following characteristics:

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

[0080] (4);

[0081] wherein, is the mass of atom i, is the spatial coordinate, is the velocity of the corresponding atom, is the volume of the characterization unit, and W is the Virial term. 、 is the spatial coordinate (x, y, z), respectively, is the velocity vector is Or The velocity component in the direction, Can be = x, also can be = y, also can be = z.

[0082] The multiscale numerical simulation method involved in the application can also have the following characteristics:

[0083] Step 1, after applying a macroscopic deformation field, the unit node is displaced to form a unit strain;

[0084] Step 2, the unit strain acts on the molecular group representation unit, the molecules in the unit are rearranged, the intermolecular force is changed, and a macroscopic stress response is caused;

[0085] Step 3, the stress response is then mapped to the macroscopic unit and integrated to the node force;

[0086] Step 4, solve the equilibrium equation, adjust the node displacement, until the molecular group representation unit enters the equilibrium state.

[0087] The molecular group representation unit simulation involved in the multiscale numerical simulation method of the application can also have the following characteristics:

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

[0089] In affine deformation, the new coordinates (x ) are generated from the initial coordinates (x ) through the following translation, rotation and uniform deformation:

[0090] ;

[0091] ;

[0092] ;

[0093] Where a, b, c are the projection coefficients of the three axes x new On the old coordinate axis before deformation, similarly, d, e, f and h, i, j are the projection coefficients of y new And z new Corresponding, k, l, m are the three translation components of the coordinate center.

[0094] For example, Figure 1As shown, the present invention relates to a fully coupled multi-scale simulation method for material mechanical properties with molecular-level precision, comprising macroscopic material geometric modeling and mesh generation; establishing microscopic molecular cluster characterization units based on the material's chemical formula and molecular structure; solidifying Gaussian points by combining macroscopic and microscopic models to form a multi-scale model; applying boundary conditions, solving for the macroscopic strain of the unit and mapping it to the microscopic molecular cluster characterization units to obtain macroscopic stress, returning to the macroscopic model to solve the equilibrium equations; and finally, conducting macroscopic and microscopic 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 this invention includes both macroscopic and microscopic components.

[0096] First, based on the microscopic uniaxial compression experiment example, a macroscopic numerical experimental model was designed and a geometric model was established. The sample size was selected as a cylinder with a diameter of Φ1.5×3.0mm, and a mesh was generated to establish the macroscopic model as follows: Figure 2 As shown in Figure 21.

[0097] Then, at the microscopic level, molecular cluster characterization units are established based on the chemical formula and molecular structure characteristics of the material. In the examples, units with the chemical formula [missing information] are selected. The metallic glass material has an amorphous structure, and the multiple molecular clusters formed are characterized by units such as... Figure 2 As shown in Figure 22.

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

[0099] like Figure 3 As shown, the molecular cluster units of the metallic glass material involved in this invention are established using 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 this particle generation based on the initial energy; repeating the above steps until the set target density is reached.

[0100] like Figure 4 As shown, the conjugate gradient descent algorithm involved in this invention includes: reading the interaction potential and molecular topology; allocating initial position and velocity and calculating the corresponding energy gradient search direction; finding the optimal step size along the current search direction; calculating the conjugate parameters; and updating the search direction based on the conjugate parameters. The above steps are repeated until the new energy gradient is less than a set threshold.

[0101] like Figure 5 As shown, the multi-scale simulation method involved in this invention applies loads to the model using displacement-controlled loading with a loading rate of 0.01 μs / s. -1, the material macroscopic deformation 51 is obtained, and the stress response of the molecular group representation unit is simulated at the same time, formula (4) is solved, and the micro evolution characteristics 52 of the molecular group are obtained. The material shows a band-shaped damage throughout the sample in macroscopic performance, and the local strain characteristics of the molecular group representation unit in the material are analyzed and counted, and it is found that the molecular group shows a local band-shaped damage characteristic in micro performance, resulting in the macroscopic bearing failure of the unit.

[0102] The implementation basis of each embodiment of the present application is realized by the programmed processing of the device with the processor function. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present application are packaged into various modules. Based on this actual situation, on the basis of each embodiment described above, the embodiment of the present application provides a material mechanics characteristic full-coupling multi-scale simulation system with molecular scale precision, which is used to execute one of the material mechanics characteristic full-coupling multi-scale simulation methods with molecular scale precision in the above method embodiment.

[0103] Referring to Figure 6 , the system comprises: a first main module, which is used to establish a material macroscopic numerical geometry model based on a material macroscopic mechanics physical experiment sample, and perform grid division on a calculation unit comprising a Gauss point; a second main module, which is used to establish a micro molecular group representation unit based on a material chemical formula and in combination with a molecular structure; a third main module, which is used to establish the correlation between the physical mechanics characteristics of the molecular group representation unit and the stress and strain response of the Gauss point of the macroscopic unit, materialize the Gauss point, and form a multi-scale model; a fourth main module, which is used to apply a boundary condition, obtain an element strain according to the macroscopic deformation of the material, apply the element strain in the molecular group representation unit, adopt molecular dynamics for simulation, express the mechanics response through the molecular group representation unit, return to the macroscopic numerical geometry model to solve a mechanics balance equation, and simulate the macroscopic deformation of the material; and a fifth main module, which is used to obtain the macroscopic parameters of the material according to the multi-scale simulation result.

[0104] The material mechanics characteristic full-coupling multi-scale simulation system with molecular scale precision provided by the embodiment of the present application adopts Figure 6 several modules, directly designs the material through the chemical composition, establishes a numerical model to simulate the mechanics behavior of the material, truly reacts the micro mechanics response of the material, and greatly reduces the calculation amount of the molecular material simulation.

[0105] It should be noted that the system embodiments provided by the present application are used to implement the methods in the above method embodiments, and are also used to implement the methods in other method embodiments provided by the present application, the difference is only that the corresponding function modules are set, and the principle is basically the same as that of the above system embodiments provided by the present application, as long as the person skilled in the art improves the modules in the above system embodiments on the basis of the above system embodiments, refers to the specific technical solutions in other method embodiments, obtains the corresponding technical means by combining technical features, and the technical solutions composed of these technical means, on the premise of ensuring the practicability of the technical solutions, the corresponding system class embodiments are obtained, which are used to implement the methods in other method class embodiments. For example:

[0106] Based on the content of the above system embodiment, as a preferred embodiment, the material mechanics property full coupling multiscale simulation system with molecular scale precision provided in the embodiment of the present application, the macro numerical simulation method includes but is not limited to material point method, smooth particle method or finite element method.

[0107] Based on the content of the above system embodiment, as a preferred embodiment, the material mechanics property full coupling multiscale simulation system with molecular scale precision provided in the embodiment of the present application, the calculation unit grid is divided to form nodes, the control equation of the substance is solved based on the nodes, the control equation of the substance includes the mass conservation equation and the momentum conservation equation, and the functional relationship expression of the mass conservation equation and the momentum conservation equation is as follows:

[0108] (1);

[0109] (2);

[0110] Among them, is the density of the substance, is the object velocity, is the stress tensor, is the material body force; is the gradient operator.

[0111] Based on the content of the above system embodiment, as a preferred embodiment, in the material mechanics property full coupling multiscale simulation system with molecular scale precision provided in the embodiment of the present application, when the grid is divided to calculate the unit, the Gaussian point information is extracted, which is used for element stress integration, and the element stress is integrated to the node force through the basis function, and the functional relationship expression of the node force is as follows:

[0112] (3);

[0113] Among them, is the node force, p is the material point, is the calculation domain, is the value of the basis function at node I for the Gaussian point, is the stress tensor.

[0114] Based on the content of the above system embodiment, as a preferred embodiment, in the material mechanics property full coupling multiscale simulation system with molecular scale precision provided in the embodiment of the application, the function relationship expression of the macro unit Gaussian point stress strain response of the molecular group representation unit is:

[0115] (4);

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

[0117] Based on the content of the above system embodiment, as a preferred embodiment, in the material mechanics property full coupling multiscale simulation system with molecular scale precision provided in the embodiment of the application, the multiscale simulation further includes:

[0118] After the macroscopic deformation field is applied, the unit node is displaced to form a unit strain;

[0119] The unit strain acts on the molecular group representation unit, the molecules in the unit are rearranged, the intermolecular force is changed, and a macroscopic stress response is caused;

[0120] The stress response is then mapped to the macro unit and integrated to the node force;

[0121] The equilibrium equation is solved, the node displacement is adjusted, and the molecular group representation unit is adjusted until the molecular group representation unit enters the equilibrium state.

[0122] Based on the content of the above system embodiment, as a preferred embodiment, in the material mechanics property full coupling multiscale simulation system with molecular scale precision provided in the embodiment of the application, the unit strain acting on the molecular group representation unit includes:

[0123] Molecular dynamics is used for simulation, affine deformation is first performed on the entire molecular group representation unit, the molecular group representation unit is moved to the equilibrium point in the current state by the conjugate gradient descent method, and the stress tensor is calculated according to the function relationship expression of the macro unit Gaussian point stress strain response.

[0124] Based on the same inventive concept as the foregoing embodiments, the embodiments of the present application also provide a computer device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the steps of a material mechanics property full-coupling multiscale simulation method with molecular scale precision when executing the computer program, as follows:

[0125] Based on a material macroscopic mechanics physical experiment sample, a material macroscopic numerical geometry model is established, and a macroscopic numerical simulation method is used to divide the calculation unit including the Gauss point into grids;

[0126] Based on a material chemical molecular formula, a molecular group representation unit is established in combination with a molecular structure;

[0127] The correlation between the physical mechanics property of the molecular group representation unit and the stress and strain response of the Gauss point of the macroscopic unit is established, the Gauss point is solidified, and a multiscale model is formed;

[0128] Boundary conditions are applied, the element strain is calculated according to the macroscopic deformation of the material, the element strain is applied to the molecular group representation unit, molecular dynamics is used for simulation, the mechanical response is expressed through the molecular group representation unit, the macroscopic numerical geometry model is returned to solve the mechanical equilibrium equation, and the macroscopic deformation of the material is simulated;

[0129] According to the multiscale simulation result, the macroscopic parameters of the material are obtained.

[0130] Based on the same inventive concept as the foregoing embodiments, the embodiments of the present application also provide a non-transitory computer readable storage medium storing computer instructions, the computer instructions causing a computer to execute the steps of a material mechanics property full-coupling multiscale simulation method with molecular scale precision, as follows:

[0131] Based on a material macroscopic mechanics physical experiment sample, a material macroscopic numerical geometry model is established, and a macroscopic numerical simulation method is used to divide the calculation unit including the Gauss point into grids;

[0132] Based on a material chemical molecular formula, a molecular group representation unit is established in combination with a molecular structure;

[0133] The correlation between the physical mechanics property of the molecular group representation unit and the stress and strain response of the Gauss point of the macroscopic unit is established, the Gauss point is solidified, and a multiscale model is formed;

[0134] Boundary conditions are applied, the element strain is calculated according to the macroscopic deformation of the material, the element strain is applied to the molecular group representation unit, molecular dynamics is used for simulation, the mechanical response is expressed through the molecular group representation unit, the macroscopic numerical geometry model is returned to solve the mechanical equilibrium equation, and the macroscopic deformation of the material is simulated;

[0135] According to the multiscale simulation result, the macroscopic parameters of the material are obtained.

[0136] In summary of the above embodiments, the present application performs numerical geometric modeling based on a material macroscopic experimental sample, divides grid cells and extracts Gaussian point information; establishes a molecular group representation unit according to a material chemical molecular formula and a molecular structure; solidifies the Gaussian point through the molecular group representation unit, and relates the mechanical state of the grid cell Gaussian point to the statistical mechanics characteristics of the molecular group; iteratively simulates by applying boundary conditions, obtains the strain of the material macroscopic deformation, applies it in the molecular group representation unit, after the molecular level calculation, statistically obtains the microscopic mechanical properties of the molecular group representation unit and feeds back the material macroscopic stress to solve the mechanical equilibrium equation; through the above process, the material experimental loading process can be simulated, and the material strength, stiffness and other macroscopic parameter information can be obtained. The method provides an effective simulation prediction means for the design of high-performance materials based on the molecular level, and greatly reduces the material research and design cost and the experimental period.

[0137] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present application.

Claims

1. A method of full-coupled multiscale simulation of material mechanical properties with molecular scale precision, characterized in that, The method comprises the following steps: Based on the material macroscopic mechanics physical experiment sample, a material macroscopic numerical geometry model is established, and the calculation unit including the Gauss point is meshed based on the macroscopic numerical simulation method; Based on the material chemical molecular formula, a molecular group representation unit is established in combination with the molecular structure; The correlation between the physical and mechanical properties of the molecular group representation unit and the stress and strain response of the macroscopic unit Gauss point is established, the Gauss point is solidified, and a multiscale model is formed; The correlation function relationship expression between the physical and mechanical properties of the molecular group representation unit and the stress and strain response of the macroscopic unit Gauss point is as follows: ； where m is the mass of the atom i i , a, b are spatial coordinates, v is the velocity of the corresponding atom, vol is the unit volume, and W is the Virial term.​ Boundary conditions are applied, the element strain is calculated according to the macroscopic deformation of the material, the element strain is applied to the molecular group representation unit, molecular dynamics is used for simulation, the mechanical response of the molecular group representation unit is expressed, the mechanical equilibrium equation of the macroscopic numerical geometry model is solved, and the macroscopic deformation of the material is simulated; According to the multiscale simulation result, the macroscopic parameters of the material are obtained; The multiscale simulation method further comprises: After the macroscopic deformation field is applied, the element node is displaced to form an element strain; The element strain acts on the molecular group representation unit, the molecules in the element are rearranged, the intermolecular force is changed, and a macroscopic stress response is caused; The stress response is then mapped to the macroscopic element and integrated to the node force; The equilibrium equation is solved, the node displacement is adjusted, and the molecular group representation unit is in an equilibrium state; The element strain acting on the molecular group representation unit comprises: using molecular dynamics to simulate the molecular dynamic process in the molecular group representation unit, performing affine deformation on the entire molecular group representation unit, moving the molecular group of the molecular group representation unit to the equilibrium point in the current state by the conjugate gradient descent method, and calculating the stress tensor according to the function relationship expression of the macroscopic unit Gauss point stress and strain response.

2. The method of claim 1, wherein the method is characterized by, 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. The method of claim 1, wherein the method is characterized by, The calculation unit is meshed to form nodes, and the control equation of the material is solved based on the nodes, the control equation of the material includes the mass conservation equation and the momentum conservation equation, and the function relationship expression of the mass conservation equation and the momentum conservation equation is as follows: ； ； where p is the density of the material, t is time, v is the velocity of the object, s is the stress tensor, b is the body force of the material; and V is the gradient operator.

4. The method of claim 3, wherein the method is characterized by, When the calculation unit including the Gauss point is meshed, the Gauss point information is extracted for element stress integration, and the element stress is integrated to the node force through the basis function, and the function relationship expression of the node force is as follows: ； where, F I is the nodal force, p is the material point, Ω is the computational domain, is the value of the basis function at the node I for the Gauss point, σ is the stress tensor.

5. A material mechanics property fully coupled multiscale simulation system with molecular scale precision, for implementing a material mechanics property fully coupled multiscale simulation method with molecular scale precision as claimed in claim 1, characterized in that, It comprises: A first main module is used for establishing a material macroscopic numerical geometry model based on a material macroscopic mechanics physical experiment sample, and meshing a calculation unit including a Gauss point; A second main module is used for establishing a micro molecular group representation unit based on a material chemical molecular formula in combination with a molecular structure; A third main module is used for establishing the correlation between the physical and mechanical properties of the molecular group representation unit and the stress and strain response of the macroscopic unit Gauss point, solidifying the Gauss point, and forming a multiscale model; a fourth main module for applying boundary conditions, obtaining element strain according to macroscopic deformation of the material, applying the element strain in the molecular group representation element, simulating by molecular dynamics, expressing mechanical response through the molecular group representation element, returning to the macroscopic numerical geometric model to solve the mechanical equilibrium equation, and simulating macroscopic deformation of the material; a fifth main module for obtaining macroscopic parameters of the material according to the multi-scale simulation result. 6.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-5 when the computer program is executed by the processor. The processor executes the computer program to implement the steps of the material mechanics characteristic full-coupling multi-scale simulation method with molecular scale precision according to any one of claims 1 to 4.

7. A non-transitory computer-readable storage medium, comprising: The non-transitory computer readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the steps of the material mechanics characteristic full-coupling multi-scale simulation method with molecular scale precision according to any one of claims 1 to 4.

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