Molecular dynamics simulation analysis method and system for hydrodynamic properties of aluminum gel

Abstract

The embodiment of the application discloses a kind of molecular dynamics simulation analysis method and system of the hydraulic performance of aluminum gel, it includes: S1, based on gibbsite or bayer gibbsite crystal structure, construct anhydrous aluminum gel cluster model and form initial simulation configuration;S2, initial simulation configuration is balanced to NVT, and simulation configuration with stable hydration structure is formed;S3, based on the simulation configuration, obtain a series of water layer thickness controllable aluminum gel cluster model;S4, based on each water layer thickness controllable aluminum gel cluster model, construct three-dimensional aluminum gel structure model capable of simulating the stacking state of cluster in space;S5, molecular dynamics simulation is carried out to the three-dimensional aluminum gel structure model to obtain simulation analysis result.The application realizes the accurate prediction analysis of the mechanical properties of aluminum gel by constructing cluster model based on gibbsite / bayer gibbsite, and systematically controlling the uniaxial tensile simulation of gel water content.

Description

Technical Field

[0001] This invention relates to the field of materials micromechanical calculation and analysis technology, and in particular to a molecular dynamics simulation analysis method and system for the mechanical properties of hydrated aluminum gel. Background Technology

[0002] Sulfoaluminate cement (SAC) is a low-carbon special cement mainly composed of anhydrous calcium sulfoaluminate and dicalcium silicate minerals. In SAC, ettringite (AFt) accounts for 50%–60% of the total hydration products and is the main source of early strength development. In contrast, another key hydration product—aluminum gel (mainly AH3 phase)—although its content is less than 30%, has a specific surface area that is more than three times that of traditional calcium silicate hydrate (CSH), resulting in significantly enhanced van der Waals forces and cohesion. It plays a crucial role in regulating the macroscopic mechanical properties of cement paste, especially contributing significantly to long-term strength and toughness. Therefore, in-depth understanding of the microstructural characteristics and mechanical response mechanism of AH3 aluminum gel is of great significance for establishing a "micro-macro" performance correlation model for SAC materials.

[0003] Existing research shows that AH3 aluminum gel in SAC exhibits a nanoscale microcrystalline structure: its atomic arrangement is well-ordered in the short range due to the interaction of chemical bonds and the rational regulation of intramolecular energy, forming a locally ordered structure (locally ordered); however, as the crystal size increases, the atomic arrangement gradually loses its regularity under the combined influence of temperature, pressure and intermolecular impurities, and exhibits disordered characteristics in the long range. Therefore, using the aluminum gel cluster model to characterize aluminum gel can more accurately reproduce the actual configuration of aluminum gel than the traditional ideal continuous crystal model.

[0004] However, existing molecular simulation techniques have significant limitations and cannot be directly applied to the problems to be solved in this application, such as:

[0005] First, existing analytical models lack specificity and accuracy, making them difficult to apply to AH3 alumina gel simulation analysis technology. Current molecular simulation research techniques for cement-based materials are mostly aimed at polyelectrolyte gels, geopolymers (NASH or CASH), or calcium silicate systems. Their atomic composition, bonding mode, and topological structure are fundamentally different from those of alumina gel with Al(OH)3 octahedral as the basic unit (i.e., in terms of elemental composition, coordination environment, and bonding mode). Directly applying these existing models cannot accurately describe the unique "short-range order, long-range disorder" nanocrystal and cluster aggregation characteristics of alumina gel.

[0006] Secondly, the impact of the key structural variable—actual water content—is neglected: In real-world environments, the water content (gel water) of aluminum gel is a core variable that profoundly affects the interactions between its clusters. However, traditional modeling often assumes completely dry or saturated hydration conditions, failing to systematically consider the intermediate water content state of aluminum gel under experimental conditions. Or, although water is involved in the simulation, it is only removed as a byproduct of the polymerization reaction, without considering different gel water contents as a systematic and controllable input variable to quantitatively study its impact on the mechanical properties and failure modes of the material. Even though relevant technologies have been used to study the properties of this gel, the object is a polyelectrolyte gel, and the focus is on the activity coefficient, which is completely different from the correlation mechanism between mechanical properties and water content.

[0007] Furthermore, there is a lack of research on the interaction mechanism between clusters—in particular, existing technologies have not revealed how different water contents affect the overall mechanical properties and failure mechanism by changing the bridging atom type at the cluster interface. That is, the binding, evolution, and failure mechanism of the interface between aluminum gel clusters under different water contents are unclear.

[0008] In summary, the lack of simulation and analysis methods for aluminum gel structures that incorporate the key variable of gel water, as well as the lack of understanding of the interfacial damage mechanism between clusters, prevents existing technologies from fundamentally elucidating the mechanical properties of aluminum gels at the microscopic level. This severely restricts the ability to optimize the performance of sulfoaluminate cement materials through microscopic design. Summary of the Invention

[0009] Based on this, in order to address the shortcomings of existing technologies, a molecular dynamics simulation analysis method and system for the hydrodynamic properties of aluminum gel is proposed.

[0010] To achieve the above design objectives, the technical solution of the present invention is as follows:

[0011] A molecular dynamics simulation analysis method for the hydrodynamic properties of aluminum gel, comprising:

[0012] S1. Based on the crystal structure of gibbsite or gibbsite, construct an anhydrous aluminum gel cluster model, and form an initial simulation configuration based on the anhydrous aluminum gel cluster model.

[0013] S2. Perform NVT balancing on the initial simulation configuration to form a simulation configuration with a stable hydration structure;

[0014] S3. In the visualization modeling software, with the cluster center as the origin, and based on the simulation configuration according to a number of predefined water layer thicknesses, obtain a series of aluminum gel cluster models with controllable water layer thickness.

[0015] S4. Based on the aluminum gel cluster model with controllable water layer thickness, space is filled in a face-centered cubic lattice arrangement to construct a three-dimensional aluminum gel structure model that can simulate the stacking state of clusters in space.

[0016] S5. Perform molecular dynamics simulation on the three-dimensional aluminogel structure model to obtain simulation analysis results.

[0017] Furthermore, S1 specifically includes the following steps:

[0018] S11. Based on the crystal structure of gibbsite or gibbsite, construct an anhydrous aluminum gel cluster model;

[0019] S12. Based on a predefined simulation box, water molecules are randomly generated around the anhydrous aluminum gel cluster model to form an aluminum gel cluster model containing a water molecule layer, i.e., the initial simulation configuration.

[0020] Furthermore, S4 specifically includes the following steps:

[0021] Molecular structures were created for aluminum gel cluster models with different gel water contents according to molecular templates, and then filled in the Lammps software based on face-centered cubic lattice structures. The corresponding filling rule is that the side length of the cubic box and the side length of the FCC-style lattice are preset multiples of the diameter of the aluminum gel cluster models with different gel water contents.

[0022] Furthermore, S5 specifically includes the following steps:

[0023] S51. Configure molecular force field simulation conditions for the three-dimensional aluminogel structure model, and then define the molecular force field framework for the short-range repulsion / attraction and long-range electrostatic interaction relationships between various atoms in the aluminogel-water multiphase system for the three-dimensional aluminogel structure model.

[0024] S52. Under the molecular force field framework, the three-dimensional aluminogel structure model is subjected to energy minimization processing;

[0025] S53. Set a two-stage balancing strategy and perform balancing constraint processing on the three-dimensional aluminogel structure model based on the two-stage balancing strategy to obtain the simulation reference configuration.

[0026] S54. Perform uniaxial tensile simulation and multi-scale failure analysis on the simulated benchmark configuration to obtain the corresponding mechanical property parameters of aluminum gel and the dominant type of interfacial bond breaking, and establish the quantitative relationship between the gel water content of the aluminum gel and the mechanical property parameters of the aluminum gel. Then, based on the determined dominant type of interfacial bond breaking, give the corresponding mechanical property change analysis results.

[0027] In some more specific embodiments, S54 specifically includes the following steps:

[0028] S541. At a given temperature, the simulated reference configuration is subjected to uniform uniaxial tensile simulation along a one-dimensional direction until the model fractures. Stress-strain data are collected simultaneously and atomic motion trajectory files are output.

[0029] S542. Based on the stress-strain data, calculate the corresponding mechanical property parameters of the aluminum gel, namely the Young's modulus, ultimate tensile strength, strain energy density and failure strain of the aluminum gel.

[0030] S543. Based on the atomic motion trajectory file, perform visualization analysis and count the number of Al-OH bonds formed by aluminum atoms and hydroxyl oxygen atoms and Al-OW bonds formed by aluminum atoms and water molecule oxygen atoms during the stretching process. Calculate the bond breakage normalization number to determine the dominant type of interfacial bond breakage under different gel water contents.

[0031] S544. Establish a quantitative relationship between the gel water content of the aluminum gel and the various macroscopic mechanical property parameters obtained in step S542, and analyze the reasons for the changes in the macroscopic mechanical properties in conjunction with the interface bond breaking type determined in step S543.

[0032] In some more specific embodiments, determining the dominant type of interfacial bond breakage under different gel water contents includes calculating the number of Al-OH bonds formed between aluminum atoms and hydroxyl oxygen atoms, and Al-OW bonds formed between aluminum atoms and water molecule oxygen atoms during stretching, and quantitatively analyzing the failure mechanism of the aluminum gel by calculating the bond breakage normalized number; wherein, the bond breakage normalized number is calculated by the following formula:

[0033]

[0034] In the formula, Represents the normalized number of broken bonds. N and N 0 represents the number of a certain bond under a specific strain state and the initial strain state, respectively.

[0035] In some more specific embodiments, the two-stage balancing strategy includes: a first balancing constraint stage, which first applies spring constraints to the water molecules of the three-dimensional aluminogel structure model and performs NVT balancing; and a second balancing constraint stage, which performs full-system anisotropic NPT balancing on the three-dimensional aluminogel structure model after NVT balancing to obtain the simulation baseline configuration.

[0036] Based on the same inventive essence, this application also proposes a molecular dynamics simulation analysis system for the hydrodynamic properties of aluminum gel, which includes:

[0037] The preprocessing unit is used to construct an anhydrous alumina gel cluster model based on the crystal structure of gibbsite or gibbsite, and to form an initial simulation configuration based on the anhydrous alumina gel cluster model.

[0038] The first balancing unit is used to perform NVT balancing on the initial simulation configuration to form a simulation configuration with a stable hydration structure.

[0039] The model building unit is used to obtain a series of aluminum gel cluster models with controllable water layer thickness based on the simulation configuration, with the cluster center as the origin and according to a number of predefined water layer thicknesses.

[0040] The model filling unit, based on the aluminum gel cluster model with controllable thickness of each water layer, fills the space in a face-centered cubic lattice arrangement to construct a three-dimensional aluminum gel structure model that can simulate the stacking state of clusters in space.

[0041] The model simulation analysis unit is used to perform molecular dynamics simulations on the three-dimensional aluminogel structure model to obtain simulation analysis results.

[0042] Implementing the embodiments of the present invention will have the following beneficial effects:

[0043] This invention achieves accurate prediction of the mechanical properties of alumina gel by constructing a cluster model based on gibbsite / gibbsite and systematically controlling the gel water content for uniaxial tensile simulation. Furthermore, it quantitatively reveals the nonlinear variation and extreme values ​​of the macroscopic mechanical properties of alumina gel (such as strength and modulus) with water content, and elucidates the microscopic mechanism of the transformation of interfacial bonding types (Al-OH and Al-OW bonds) through bond breakage analysis, providing crucial microscopic theoretical basis for the performance optimization of sulfoaluminate cement. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] in:

[0046] Figure 1 This is a flowchart of the basic steps corresponding to the solution described in this invention;

[0047] Figure 2 This is a flowchart illustrating the effect of step 1 in an embodiment of the present invention.

[0048] Figure 3The aluminum gel cluster model corresponding to the embodiment of the present invention is filled with an FCC style model diagram;

[0049] Figure 4 These are stress-strain curves of aluminum gel cluster models with different water contents corresponding to the embodiments of the present invention;

[0050] Figure 5 The diagrams show the Young's modulus and ultimate strength of aluminum gel cluster models with different water contents corresponding to the embodiments of this invention.

[0051] Figure 6 The strain energy density and failure strain diagrams of aluminum gel cluster models with different water contents corresponding to the embodiments of the present invention are shown.

[0052] Figure 7 This is a diagram illustrating the uniaxial tensile failure process of aluminum gel corresponding to an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. It is understood that the terms “first,” “second,” etc., as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a second element without departing from the scope of this application, and similarly, a second element may be referred to as a first element. Both the first element and the second element are elements, but they are not the same element.

[0055] To deeply analyze the performance regulation mechanism of sulfoaluminate cement-based materials, this invention essentially designs a method based on molecular dynamics simulation to study the mechanical properties and failure mechanism of aluminum gel under different gel water contents, so as to design the microstructure and predict the performance of aluminum gel, the main hydration product of sulfoaluminate cement.

[0056] Based on the aforementioned design requirements, the overall architecture of this application establishes a molecular dynamics simulation analysis method for the hydrodynamic properties of aluminum gel through the following core steps:

[0057] First, construct an AH3 gel model specifically for the hydration products of sulfoaluminate cement. That is, based on the real crystal structure of the hydration product AH3 of sulfoaluminate cement, select the unit cell of gibbsite or gibbsite as the basic crystal building unit.

[0058] Secondly, a single-cluster water-bearing simulation system was established, and based on the single-cluster water-bearing simulation system, a series of cluster water-bearing simulation models with controllable water layer thickness were obtained according to several predefined water layer thicknesses.

[0059] Simultaneously, a multi-cluster assembly strategy based on FCC arrangement was used to form a multi-cluster system and obtain a three-dimensional aluminum gel structure model;

[0060] Finally, through simulation and visualization, molecular dynamics simulation was performed on the three-dimensional aluminogel structure model to obtain simulation analysis results, which determined that its mechanical properties change nonlinearly with the thickness of the water layer and that there is an extreme point law. At the same time, its tensile failure mechanism was also discovered.

[0061] Based on the above design framework, this embodiment proposes a molecular dynamics simulation analysis method for the hydrodynamic properties of aluminum gel, such as... Figure 1 As shown, the method includes the following steps:

[0062] S1. Based on the crystal structure of gibbsite or gibbsite, construct an anhydrous aluminum gel cluster model, and form an initial simulation configuration based on the anhydrous aluminum gel cluster model.

[0063] S2. Perform NVT balancing on the initial simulation configuration to form a simulation configuration with a stable hydration structure;

[0064] S3. In the visualization modeling software, with the cluster center as the origin, and based on the simulation configuration according to a number of predefined water layer thicknesses, obtain a series of aluminum gel cluster models with controllable water layer thickness.

[0065] S4. Based on the aluminum gel cluster model with controllable water layer thickness, space is filled in a face-centered cubic (FCC) lattice arrangement to construct a macroscopic three-dimensional structural model that can efficiently simulate the stacking state of clusters in space.

[0066] S5. Perform molecular dynamics simulation on the three-dimensional aluminogel structure model to obtain simulation analysis results.

[0067] In some specific embodiments, S1 specifically includes the following steps:

[0068] S11. Based on the crystal structures of gibbsite or bayerite, construct an anhydrous aluminogel cluster model. Specifically, there are two common crystal structures of aluminogel, namely gibbsite and bayerite, and the chemical formulas of both gibbsite and bayerite can be represented in the form of Al(OH)₃. In this example, bayerite is selected from the open-source Materials Project database, with its unit cell parameters a = 5.062 Å, b = 8.671 Å, c = 4.713 Å, α = 90°, β = 90.27°, γ = 90°. Subsequently, in a pre-selected software, such as Ovito, use the replicate command to expand the unit cell of the bayerite aluminogel crystal structure to obtain a three-dimensional crystal model. Then, select the atoms within the sphere range from the three-dimensional crystal model, and delete the unselected part, that is, cut out a spherical nanocluster from the three-dimensional crystal model in Ovito by the spherical truncation method (x² + y² + z² < r², where x, y, and z are coordinates respectively, and r represents the sphere radius), such as Figure 2 , to construct an initial nano-scale aluminogel cluster model with a water content of 0 (such as a diameter of 5.0 nm). In this aluminogel cluster model, the atomic molar ratio of Al 3+ to OH - is preferably 1:3 to ensure that the spherical cluster has no net charge, thereby truly simulating its microcrystalline characteristics of "short-range order and long-range disorder".

[0069] S12. Based on a predefined simulation box, place the anhydrous aluminogel cluster at the center of the simulation box, and write a water molecule txt file (in this txt file, the bond lengths between atoms are defined, such as setting the water molecule density to 1 mol / L). Through this file, randomly generate water molecules around the anhydrous aluminogel cluster model in the box, make the initial spatial positions of the water molecules in a random distribution state, and make the water molecules naturally adsorb on the cluster surface to form an aluminogel cluster model containing a water molecule layer, that is, the initial simulation configuration, namely the initial hydrated simulation system. The whole process is as shown in Figure 3 . In this step, the nano-scale cluster model combines the spherical truncation method to avoid structural distortion caused by ideal periodic crystals, providing an anhydrous reference model for the subsequent establishment of the hydrated model.

[0070] In some specific embodiments, S2. Perform NVT equilibration on the initial simulation configuration to form a simulation configuration with a stable hydrated structure, that is, a single-cluster hydrated simulation system. Specifically, it means converting the model file formed in S1 into a data file and importing it into the Lammps software to perform equilibration in the NVT ensemble (preferably, the energy convergence criterion energy_tol is less than 1.0e -6The equilibrium time was set to 500,000 fs with a time step of 1 fs, allowing randomly distributed water molecules to spontaneously and stably adsorb onto the aluminum gel surface, forming a stable hydration structure. This provides an initial configuration with a reasonable hydration structure for the subsequent construction of water content gradient models, ensuring that different water content models obtained through subsequent trimming have a consistent and reasonable initial water distribution, and avoiding distortion of interfacial interactions due to unreasonable water molecule positions.

[0071] In some specific embodiments, S3, within the visualization modeling software, taking the cluster center as the origin and according to several predefined water layer thicknesses, based on the simulated configuration, a series of aluminum gel cluster models with different water contents (i.e., controllable water layer thickness) are obtained. Specifically, within the visualization modeling software Ovito, the thickness of the water layer surrounding the aluminum gel cluster is controlled by adjusting the spherical cutoff radius (wherein the water layer thickness takes values ​​in the range of 0 nm to 1.0 nm, for example: 0, 0.3, 0.5, 0.8, 1.0 nm). By extracting all atoms within the corresponding spheres and deleting the outer portion, a series of aluminum gel model models with different gel water contents were systematically and quantitatively constructed (i.e., aluminum gel cluster models containing water layers with sphere diameters of 5, 5.3, 5.5, 5.8, and 6 nm, respectively). The data files required for molecular dynamics simulation were output, using gel water content as the core variable. By adjusting the cluster radius, the water layer thickness was designed to be controllable and precisely introduced into the control system. Thus, for the first time, a one-to-one correspondence between water content and cluster size was established to form an aluminum gel-water multiphase system.

[0072] In some specific embodiments, S4, based on the aluminum gel cluster models with controllable water layer thickness, space is filled using a face-centered cubic (FCC) lattice arrangement to construct a macroscopic three-dimensional aluminum gel structure model that can efficiently simulate the stacking state of clusters in space; specifically, this refers to creating molecular structures for aluminum gel cluster models with different gel water contents according to molecular templates, and efficiently filling them in Lammps software based on the face-centered cubic (FCC) lattice structure. The corresponding filling rule is that the side length of the cubic box and the side length of the FCC-style lattice are preset multiples of the diameter of the aluminum gel cluster models with different gel water contents, such as... The random number seed can be set to 3453, such as... Figure 3 The image shows an aluminum gel cluster model with a radius of 5.5 nm assembled in a cubic box. It can be observed that after assembly and molecular dynamics equilibrium, the interaction between the cluster interfaces of the aluminum gel cluster models with different water contents exhibits a water content dependence. That is, the interaction between the cluster interfaces comes from the bridging effect of the atomic chains. When the water content is low, the bridging chains are mainly aluminum and oxygen atom chains, while when the water content is high, the bridging chains are mainly water molecules. Therefore, it can be determined that the interfacial interaction between clusters is determined by the water content.

[0073] In some specific embodiments, S5, molecular dynamics simulation is performed on the three-dimensional aluminum gel structure model to obtain simulation analysis results; this specifically includes the following steps:

[0074] S51. Configure molecular force field simulation conditions for the three-dimensional aluminogel structure model, thereby defining a molecular force field framework for the short-range repulsion / attraction and long-range electrostatic interactions between various atoms (Al, O, H) in the aluminogel-water multiphase system. For example, import the three-dimensional aluminogel structure model into Lammps, adopt a full-atom force field model (using real units, atomic style full), and configure molecular force field simulation conditions that can describe the complex non-bonded interactions between aluminogel clusters and water molecules to provide a physical analysis basis for subsequent mechanical property prediction. Preferably, the molecular force field simulation conditions include: using the LJ / cut + coul / long combined force field and the long-range Coulomb potential solution method, i.e., Ewald summation, with a cutoff radius set to 10 Å and an accuracy set to 1.0 e. -4 Furthermore, the LJ potential parameters between different types of atoms are mixed using the arithmetic mean method; this step defines short-range van der Waals interactions using the lj / cut potential function, and accurately processes Al³ using the coul / long and Ewald summation methods. + OH - and the long-range electrostatic interaction between H2O;

[0075] S52. Within the molecular force field framework, the three-dimensional aluminogel structure model is subjected to energy minimization processing to eliminate atomic position conflicts and unreasonable internal stresses introduced by the geometric construction, so that the system reaches a stable state with the lowest local energy; wherein the force convergence criterion force_tol is set to 1.0e. -6 Kcal / (mol·Å), energy convergence criterion energy_tol set to 1.0e -6 To ensure the numerical stability and physical authenticity of subsequent molecular dynamics simulations; preferably, the maximum force iteration step number is set to 10,000 steps, and the maximum energy iteration step number is set to 10,000 steps.

[0076] S53. Set a two-stage balancing strategy and perform balancing constraint processing on the three-dimensional aluminogel structure model based on the two-stage balancing strategy to obtain a simulated baseline configuration; wherein, the two-stage balancing strategy includes: a first balancing constraint stage, that is, firstly, only spring constraints are applied to the water molecules of the three-dimensional aluminogel structure model and NVT balancing processing is performed, so that it adapts to the interface environment of the adjacent clusters while retaining the initial hydration layer distribution. Preferably, the configuration method of the first balancing constraint stage is to perform NVT balancing on the three-dimensional aluminogel structure model at a temperature of 298K, use the shake algorithm to fix the bond length and bond angle of the water molecules, apply a spring force to the oxygen atoms of the water molecules with a spring constant of 0.3, and bind them near the initial position, with 200 balancing steps. Step 0; The second equilibrium constraint stage, namely, performing full-system anisotropic NPT equilibrium on the three-dimensional aluminogel structure model after NVT equilibrium processing to simulate the reference configuration for stretching. Preferably, the configuration method of the first equilibrium constraint stage refers to performing NPT simulation on all atoms of the three-dimensional aluminogel structure model after NVT equilibrium processing, with anisotropic pressure control, a target pressure of 0 atm, running for 100,000 steps, and recording the z-axis length of the box at this time as the reference length for stretching. It can be seen that this scheme first adopts a two-stage equilibrium scheme of "first equilibrating water molecules and then equilibrating the whole system to zero pressure", which can effectively avoid the structural instability problem that is very easy to occur in the water-containing nanocluster model when directly equilibrating all atoms, thereby ensuring the physical reliability of subsequent stretching simulation.

[0077] S54. Perform uniaxial tensile simulation and multi-scale failure analysis on the simulated benchmark configuration to obtain the corresponding mechanical property parameters of aluminum gel and the dominant type of interfacial bond breaking, and establish the quantitative relationship between the gel water content of the aluminum gel and the mechanical property parameters of the aluminum gel. Then, based on the determined dominant type of interfacial bond breaking, give the corresponding mechanical property change analysis results.

[0078] In some more specific embodiments, S54 specifically includes the following steps:

[0079] S541. Perform uniaxial tensile molecular dynamics simulations to evaluate the mechanical behavior of the alumina gel: At a given temperature, perform uniform uniaxial tensile simulations along a one-dimensional direction on the simulation baseline configuration until the model fractures. Simultaneously acquire stress-strain data and output atomic motion trajectory files, i.e., data files containing atomic coordinates; for example, in the Lammps software, using the NVT system, apply a constant tensile strain rate along the z-axis of the model construction direction to perform uniaxial tensile simulations, as shown in the figure, with the temperature constant at 298K and the tensile strain rate at 0.00008 fs. -1The time step is 1 fs, the strain time is 10000 fs, and the simulation continues until the total strain reaches the preset value (e.g., 0.8). At this point, the stress value drops from the peak value to below 10% of its peak value, indicating that the model has fractured. The tensile simulation of the model uses periodic boundary conditions in the x, y, and z directions. Based on the material properties of the simulated volume, strain is defined as the relative change in the length of the simulated box in the z-direction compared to the equilibrium length before stretching; that is, the difference between the length of the simulated box in the z-direction and the initial equilibrium length divided by the initial length. To ensure configurable data accuracy, stress data is collected every 25 steps, and the data from five consecutive collections are averaged. Stress data is output every 125 steps, and finally, an averaged stress-strain data point is output every 125 steps, thus obtaining a smooth and reliable stress-strain curve, such as... Figure 4 As shown;

[0080] S542. Based on the stress-strain data, calculate the corresponding mechanical property parameters of the aluminum gel, namely the Young's modulus, ultimate tensile strength, strain energy density and failure strain of the aluminum gel; the Young's modulus, ultimate strength, strain energy density and failure strain are calculated through the aforementioned curves.

[0081] S543. Based on the atomic motion trajectory file, perform visualization analysis and count the number of Al-OH bonds formed between aluminum atoms and hydroxyl oxygen atoms, and the number of Al-OW bonds formed between aluminum atoms and water molecule oxygen atoms during stretching. Calculate the bond breakage normalization number to determine the dominant type of interfacial bond breakage under different gel water contents. Specifically, this refers to the atomic motion trajectory file containing the coordinates of all atoms changing over time. Import this file into visualization post-processing software such as Ovito, count the number of bonds under specific strain states and initial strain states, calculate the bond breakage normalization number for different atomic pairs, and deeply analyze the mechanical properties and failure mechanisms of aluminum gels with different gel water contents. This enables visualization analysis of model deformation and microstructure evolution during stretching (e.g., Figure 7 As shown in the image), the visualization analysis clearly shows that the bond breakage during the stretching process of the aluminum gel in its dry state is mainly Al-O. H Fracture is the primary process. In the aqueous state, the fracture is mainly Al-O. W The aluminum gel clusters exhibit strong cohesion, primarily composed of bonds. The structural breakage mechanism manifests as interfacial fracture, with key interfacial interactions stemming from atomic chain bridging. Specifically, the breakage occurs at the interfaces between aluminum gel clusters, meaning the water content regulates the interfacial bonding type. At low water content, the bridging chains are primarily aluminum and oxygen atom chains, while at high water content, they are primarily water molecule chains. This directly demonstrates that water molecules alter the chemical properties of the interfacial bridging chains.

[0082] S544. Establish a quantitative relationship between the gel water content of the aluminum gel and the various macroscopic mechanical property parameters obtained in step S542, and analyze the reasons for the changes in the macroscopic mechanical properties in conjunction with the interface bond breaking type determined in step S543.

[0083] Therefore, the breakage mechanism of the aluminum gel can be quantitatively analyzed by calculating the number of Al-OH bonds formed between aluminum atoms and hydroxyl oxygen atoms, and the number of Al-OW bonds formed between aluminum atoms and water molecule oxygen atoms during the stretching process, and calculating the bond breakage normalized number. The bond breakage normalized number is calculated using the following formula:

[0084]

[0085] In the formula, Represents the normalized number of broken bonds. N and N 0 represents the number of a certain bond under specific strain state and initial strain state, respectively. For example, under the initial state (strain ε=0) and a series of specific strain states, the number of all Al-OH and Al-OW bonds in the system is identified and counted by using set cutoff radii (e.g., the cutoff radius for identifying Al-O bonds is 2.5 Å, the cutoff radius for identifying OH bonds in hydroxyl groups is 1.2 Å, and the cutoff radius for the atomic pairs in hydroxyl groups formed by hydrogen and oxygen in aluminum octahedra and oxygen and hydrogen in water is 2.4 Å). The above formula is used to explore the bond breaking mechanism and the mechanism of intermolecular interaction during uniaxial stretching. Furthermore, the water content of aluminum gel determines the interfacial strength and toughness by regulating the chemical nature of the interfacial bridging chains between aluminum gel nanoclusters (strong covalent / ionic Al-OH bonds and weak hydrogen / coordinated Al-OW bonds), which ultimately manifests as a nonlinear dependence of macroscopic mechanical properties and the appearance of extreme points.

[0086] In summary, S54 achieved a quantitative correlation analysis among the macroscopic mechanical properties, microscopic bond breaking mechanism, and gel water content of aluminum gel. It can not only accurately predict the mechanical properties of aluminum gel under different water contents, but more importantly, it reveals that the microscopic root cause of its performance changes lies in the transformation of the interfacial bridging bond type. This provides a direct theoretical basis for optimizing material performance by precisely controlling the water content.

[0087] Meanwhile, the corresponding simulation results also demonstrate the correctness of this step. For example, by analyzing the stress-strain curve, the slope in the elastic deformation stage is calculated to obtain the Young's modulus, and the ultimate strength is the maximum stress that the model can withstand. Figure 5 As shown; the strain energy density is obtained by integrating the area under the stress-strain curve, and the failure strain is the strain corresponding to zero stress, as shown. Figure 6 .from Figure 5The data shows that the relationship between the size of the aluminum gel clusters and the thickness of the water layer is nonlinear, and extreme values ​​appear at specific sizes. The Young's modulus and ultimate strength are the largest in the aluminum gel with a radius of 5.3 nm, and the smallest in the Bayesian gibbsite aluminum gel with a radius of 5.5 nm. Figure 6 The variation trends of intermediate strain energy density and failure strain are basically consistent, both reaching the maximum in the 5.0 nm radius boehmite aluminate gel and the minimum in the 5.5 nm radius aluminate gel. This indicates that the 5.5 nm radius boehmite aluminate gel is more prone to failure, suggesting that the water layer thickness has a significant impact on the mechanical properties of boehmite aluminate gel.

[0088] Based on the same inventive concept, this invention also proposes a molecular dynamics simulation analysis system for the hydrodynamic properties of aluminum gel, comprising:

[0089] The preprocessing unit is used to construct an anhydrous alumina gel cluster model based on the crystal structure of gibbsite or gibbsite, and to form an initial simulation configuration based on the anhydrous alumina gel cluster model.

[0090] The first balancing unit is used to perform NVT balancing on the initial simulation configuration to form a simulation configuration with a stable hydration structure.

[0091] The model building unit is used to obtain a series of aluminum gel cluster models with controllable water layer thickness based on the simulation configuration, with the cluster center as the origin and according to a number of predefined water layer thicknesses.

[0092] The model filling unit, based on the aluminum gel cluster model with controllable thickness of each water layer, fills the space in a face-centered cubic lattice arrangement to construct a three-dimensional aluminum gel structure model that can simulate the stacking state of clusters in space.

[0093] The model simulation analysis unit is used to perform molecular dynamics simulations on the three-dimensional aluminogel structure model to obtain simulation analysis results.

[0094] Based on the same inventive concept, the present invention also proposes a computer-readable storage medium including computer instructions that, when executed on a computer, cause the computer to perform the method described thereon.

[0095] Based on the same inventive concept, the present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method when executing the program.

[0096] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method of analysis of the molecular dynamics of the hydrodynamic properties of an aluminum gel, characterized by, The method comprises the following steps: S1, based on the crystal structure of gibbsite or Bayer gibbsite, a model of an anhydrous aluminum gel cluster is constructed, and an initial simulation configuration is formed based on the model of the anhydrous aluminum gel cluster; S2, the initial simulation configuration is balanced in NVT to form a simulation configuration with a stable hydration structure; S3, in the visualization modeling software, taking the center of the cluster as the origin, based on the simulation configuration, a series of aluminum gel cluster models with controllable water layer thickness are obtained according to a pre-defined water layer thickness; S4, based on each of the aluminum gel cluster models with controllable water layer thickness, space filling is performed in a face-centered cubic lattice arrangement manner to construct a three-dimensional aluminum gel structure model capable of simulating the stacking state of the cluster in space; S5, molecular dynamics simulation is performed on the three-dimensional aluminum gel structure model to obtain simulation analysis results.

2. The method of claim 1, wherein the aluminum gel is characterized by, The S1 specifically comprises the following steps: S11, based on the crystal structure of gibbsite or Bayer gibbsite, a model of an anhydrous aluminum gel cluster is constructed; S12, based on a pre-defined simulation box, water molecules are randomly generated around the anhydrous aluminum gel cluster model to form an aluminum gel cluster model containing a layer of water molecules, i.e. an initial simulation configuration.

3. The method of claim 1, wherein the aluminum gel is characterized by, The S4 specifically comprises the following steps: The aluminum gel cluster models with different gel water contents are created into molecular structures according to molecular templates, and filling is performed in the Lammps software according to the face-centered cubic lattice structure as the reference, and the corresponding filling rule is that the edge length of the cubic box and the lattice edge length of the FCC pattern are a pre-set multiple of the diameter of the aluminum gel cluster model with different gel water contents.

4. The method of claim 1, wherein the aluminum gel is characterized by, The S5 specifically comprises the following steps: S51, a molecular force field simulation condition is configured for the three-dimensional aluminum gel structure model, and a molecular force field framework of short-range repulsion / attraction and long-range electrostatic interaction between various atoms in the aluminum gel-water multiphase system is defined for the three-dimensional aluminum gel structure model; S52, energy minimization processing is performed on the three-dimensional aluminum gel structure model under the molecular force field framework; S53, a two-stage equilibrium strategy is set, and equilibrium constraint processing is performed on the three-dimensional aluminum gel structure model based on the two-stage equilibrium strategy to obtain a simulation reference configuration; S54, uniaxial stretching simulation and multi-scale damage analysis are performed on the simulation reference configuration to obtain corresponding aluminum gel mechanical property parameters and interface bond breaking dominant types, and a quantitative relationship between the gel water content of the aluminum gel and the aluminum gel mechanical property parameters is established, and then combined with the determined interface bond breaking dominant type, corresponding mechanical property change analysis results are given.

5. The molecular dynamics simulation analysis method for the aqueous mechanical properties of the aluminum gel according to claim 4, wherein S54 specifically comprises the following steps: S541, under a given temperature, uniform uniaxial stretching simulation is performed on the simulation reference configuration in a one-dimensional direction until the model breaks, stress-strain data is synchronously collected, and an atomic trajectory file is output; S542, based on the stress-strain data, corresponding aluminum gel mechanical property parameters, i.e. the Young's modulus, ultimate tensile strength, strain energy density and failure strain of the aluminum gel are calculated. S543, based on the atomic motion trajectory file, visual analysis is performed, and the number of broken Al-OH bonds formed by aluminum atoms and hydroxyl oxygen atoms and the number of broken Al-OW bonds formed by aluminum atoms and water molecule oxygen atoms in the stretching process are counted, the broken bond normalization number is calculated, and the dominant type of interface broken bond under different gel water contents is determined; S544, the quantitative relationship between the gel water content of the aluminum gel and each macroscopic mechanical property parameter obtained in step S542 is established, and the dominant type of interface broken bond determined in step S543 is combined to analyze the reason for the change of the macroscopic mechanical property.

6. The molecular dynamics simulation analysis method of the aqueous mechanical property of the aluminum gel according to claim 5, characterized in that, determining the dominant type of interface broken bond under different gel water contents comprises counting the number of broken Al-OH bonds formed by aluminum atoms and hydroxyl oxygen atoms and the number of broken Al-OW bonds formed by aluminum atoms and water molecule oxygen atoms in the stretching process, calculating the broken bond normalization number, and quantitatively analyzing the failure mechanism of the aluminum gel; wherein the broken bond normalization number is calculated by the following formula: wherein represents the number of broken bonds normalized, N and N 0 represents the number of bonds in a certain state of strain and in the initial state of strain, respectively.

7. The molecular dynamics simulation analysis method of the aqueous mechanical property of the aluminum gel according to claim 5, characterized in that, the two-stage equilibrium strategy comprises: a first equilibrium constraint stage, that is, first applying a spring constraint only to the water molecules of the three-dimensional aluminum gel structure model and performing NVT equilibrium processing; and a second equilibrium constraint stage, that is, performing full-system anisotropic NPT equilibrium on the three-dimensional aluminum gel structure model after NVT equilibrium processing to obtain a simulation reference configuration.

8. A molecular dynamics simulation analysis system based on the method of one of claims 1 to 7, characterized in that comprise: a preprocessing unit configured to construct an anhydrous aluminum gel cluster model based on the crystal structure of bayerite or bayerdellite, and form an initial simulation configuration based on the anhydrous aluminum gel cluster model; a first equilibrium processing unit configured to perform NVT equilibrium on the initial simulation configuration to form a simulation configuration with a stable hydration structure; a model establishing unit configured to obtain a series of aluminum gel cluster models with controllable water layer thicknesses based on the simulation configuration with the cluster center as the origin and according to a predefined water layer thickness; a model filling unit configured to perform spatial filling on each of the aluminum gel cluster models with controllable water layer thicknesses in a face-centered cubic lattice arrangement manner to construct a three-dimensional aluminum gel structure model capable of simulating the stacking state of the clusters in space; a model simulation analysis unit configured to perform molecular dynamics simulation on the three-dimensional aluminum gel structure model to obtain simulation analysis results.

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