A method for characterizing the internal structure network of granular materials based on inter-particle contact

Abstract

The application discloses a granular material internal structure network characterization method based on intergranular contact, which comprises the following steps: S1, constructing a particle center coordinate table and a contact data table; S2, constructing an initial node coordinate table and an initial triangular facet vertex serial number table; S3, constructing a particle boundary polygon vertex serial number table; S4, performing area judgment on all initial triangular facets in the initial triangular facet set, performing segmentation and correction as required, generating solid triangular facets and pore triangular facets, and respectively merging to form solid units and pore units; S5, based on pore centers, dividing the pore units, respectively merging with the solid units sharing an edge to form solid cells, and constructing a solid cell vertex serial number table; S6, based on particle centers, dividing the solid units, respectively merging with the pore units sharing an edge to form pore cells, and constructing a pore cell vertex serial number table; and S7, constructing a solid cell adjacency table and a pore cell adjacency table. Thus, the double-cell network characterization of the granular material internal structure is realized.

Description

Technical Field

[0001] This invention relates to the field of characterization and topology analysis of the internal structure of particulate materials, and in particular to a method for characterizing the internal structure network of particulate materials based on interparticle contact. Background Technology

[0002] The macroscopic mechanical properties of granular materials are closely related to their internal structure. Granular systems consist of a large number of particles and their contact relationships, and their internal structure exhibits discreteness, randomness, and complexity. With the development of structural characterization methods, the characterization of the internal structure of granular materials needs to reflect not only their geometric features but also the connectivity and topological organization between particles or cells, in order to form a data foundation that can be used for network representation and related analysis. Therefore, how to generate data results that can simultaneously characterize geometric features and topological connections is a crucial issue in the structural analysis and related numerical implementation of granular materials.

[0003] In granular materials, intergranular contacts play a crucial role in force transmission, deformation response, and overall mechanical properties. Therefore, constructing network representations based on intergranular contact relationships facilitates a systematic study of the internal structure of granular systems from the perspectives of connectivity and topological organization. In existing technologies, constructing cellular systems based on intergranular contact relationships is a typical approach, reconstructing granular systems into interconnected solid and porous cellular systems, thus providing a foundation for internal structural analysis.

[0004] In practical applications, it is also necessary to develop an implementation method that matches the actual particle-contact data, based on the aforementioned contact-based cell partitioning approach. On the one hand, it is necessary to uniformly organize and process the original particle and contact information; on the other hand, after completing the cell reconstruction, it is also necessary to further extract the adjacency relationships between cells, so that the results can reflect the topological relationships between cells while characterizing the geometric boundaries of cells, and form data representation results that can be used for network analysis.

[0005] Therefore, it is necessary to propose a network characterization method for the internal structure of particulate materials based on interparticle contact, so as to achieve unified processing of original particle and contact information, form the geometric boundary results and topological connection results of twin cells, and provide a corresponding data characterization basis for the geometric analysis, topological characterization and network analysis of the internal structure of particulate materials. Summary of the Invention

[0006] The technical problem to be solved by this invention is: to address the lack of a data characterization method based on interparticle contact that can form twin-cell network characterization results in the study of the internal structure of particulate materials, this invention provides a network characterization method for the internal structure of particulate materials based on interparticle contact, so as to form data characterization results that can be used for random network analysis.

[0007] To address the aforementioned technical problems, this invention provides a method for characterizing the internal structure network of particulate materials based on interparticle contact, the technical solution of which is as follows:

[0008] S1. Construct a particle center coordinate table and a contact data table;

[0009] S2. Generate an initial set of triangular facets based on the contact data table, and construct an initial node coordinate table and an initial triangular facet vertex number table based on the initial set of triangular facets.

[0010] S3. Generate particle boundary polygons based on the particle center coordinate table and the contact data table, and construct a particle boundary polygon vertex number table based on the particle boundary polygons;

[0011] S4. Perform region determination on all initial triangular elements in the initial triangular element set to obtain triangular elements that need to be segmented and corrected. Perform segmentation and correction on the triangular elements that need to be segmented and corrected to generate solid triangular elements and porous triangular elements. Merge the solid triangular elements and porous triangular elements to form solid units and porous units respectively.

[0012] S5. Based on the pore center, the pore unit is divided into multiple pore triangular facets, and the pore triangular facets are merged with the solid unit to form a solid cell; a solid cell vertex index table is constructed based on the solid cell;

[0013] S6. Based on the particle center, the solid unit is divided into multiple solid triangular facets, and the solid triangular facets are merged with the pore unit to form a pore cell; a pore cell vertex index table is constructed based on the pore cell.

[0014] S7. Extract the adjacency relationships between solid cells and between pore cells that have common contact points, and construct the adjacency table for solid cells and the adjacency table for pore cells.

[0015] Preferably, the particle center coordinate table in step S1 is constructed by collecting the particle center coordinates, and the particle center coordinate table records the number of each particle and its center coordinates; the contact data table is constructed by collecting the contact point coordinates and contact pair index data, and the contact data table records the number of each contact point, the coordinates of each contact point, and the numbers of the two contact objects corresponding to each contact point.

[0016] Preferably, the construction of the initial triangular element set in step S2 specifically involves: taking all contact points in the contact data table as a set of geometric vertices, performing Delaunay triangulation on the set of geometric vertices using the Bowyer-Watson algorithm to generate the initial triangular element set; the initial node coordinate table records the node number and node coordinates corresponding to all contact points, and the initial triangular element vertex number table records the vertex node number corresponding to each initial triangular element.

[0017] Preferably, in step S3, generating particle boundary polygons based on the particle center coordinate table and the contact data table specifically involves: extracting all contact points associated with any particle from the contact data table, performing Delaunay triangulation, merging the triangular facets generated by the triangulation to form the coverage area corresponding to any particle, and then extracting the outer contour of the coverage area to generate the particle boundary polygon corresponding to any particle, thus obtaining all particle boundary polygons corresponding to all particles.

[0018] Preferably, in step S3, the vertex number table of the particle boundary polygon is constructed based on the vertex node numbers and arrangement order of all particle boundary polygons.

[0019] Preferably, in step S4, region determination is performed on all initial triangular facets in the initial triangular facet set to obtain the triangular facets that need to be segmented and corrected, specifically:

[0020] When the contact object numbers of the three vertices of an initial triangular element all contain the same particle number, the initial triangular element is determined to be a solid triangular element.

[0021] When the contact object numbers of the three vertices of an initial triangular element do not contain the same particle number, and the initial triangular element does not geometrically overlap with the internal region of any particle boundary polygon, the initial triangular element is determined to be a pore triangular element.

[0022] When the contact object numbers of the three vertices of an initial triangular element do not contain the same particle number, and the initial triangular element geometrically overlaps with the internal region of any particle boundary polygon, the initial triangular element is determined to be a triangular element that needs to be segmented and corrected.

[0023] Preferably, in step S4, the triangular facets to be segmented and corrected are segmented and corrected to generate solid triangular facets and porous triangular facets, specifically as follows:

[0024] One or more sets of triangular facets that geometrically overlap with the boundary polygon of the same particle are merged to form a polygon to be segmented.

[0025] The polygon to be segmented is divided using the same particle boundary polygon to obtain a solid region polygon located inside the same particle boundary polygon and a pore region polygon located outside the same particle boundary polygon.

[0026] The solid region polygon and the pore region polygon are triangulated to generate solid triangular elements and pore triangular elements.

[0027] Preferably, in step S5, the porous unit is divided into multiple porous triangular facets, and the porous triangular facets are merged with adjacent solid units to form a solid cell. Specifically, the porous unit is divided into multiple porous triangular facets using the center point and the endpoints of each boundary side of the porous unit as vertices. For each solid unit, the porous triangular facets corresponding to the common boundary in the porous unit with which it shares a common boundary are incorporated into the solid unit to form a corresponding solid cell.

[0028] Preferably, in step S6, the solid unit is divided into multiple solid triangular facets, and the solid triangular facets are merged with adjacent pore units to form a pore cell. Specifically, the solid unit is divided into multiple solid triangular facets using the center point and the endpoints of each boundary side of the solid unit as vertices. For each pore unit, the solid triangular facets corresponding to the common boundary in the solid unit with which it shares a common boundary are incorporated into the pore unit to form a corresponding pore cell.

[0029] Preferably, in step S7, the adjacency relationships between solid cells and between porous cells with common contact points are extracted respectively. Specifically, when two solid cells or two porous cells have at least one common contact point, they are determined to be adjacent; otherwise, they are determined not to be adjacent. The solid cell adjacency table and the porous cell adjacency table represent the topological adjacency relationships between cells of the same type.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention achieves a unified characterization of geometric features and topological connectivity features in the internal structure of granular materials by constructing the geometric boundary results of solid cells and porous cells, and further extracting the adjacency relationships between cells of the same type.

[0032] 2. This invention provides a clear data organization method for the region determination, segmentation correction, and subsequent unit and cell reconstruction processes of the initial triangular facet, enabling solid units, porous units, solid cells, and porous cells to be expressed with corresponding data structures.

[0033] 3. This invention provides data representation results that can be used for random network analysis, facilitating further analysis of adjacency relationships and topological features between cells, and making it easy for related programs to call them. Attached Figure Description

[0034] Figure 1 This is a flowchart of the present invention;

[0035] Figure 2 This is a particle arrangement diagram from the embodiment;

[0036] Figure 3 This is a diagram showing the global Delaunay triangulation results in the embodiment;

[0037] Figure 4 This is a schematic diagram illustrating the initial triangular element region determination and segmentation correction in the embodiment.

[0038] Figure 5 This is a schematic diagram showing the distribution of solid units and porous units in the embodiment;

[0039] Figure 6 This is a schematic diagram of the pore unit breakdown in the embodiment;

[0040] Figure 7 The diagram shows the result of the twin-cell system constructed in the example. Detailed Implementation

[0041] The present invention will be further described below with reference to preferred embodiments. It should be understood that the following embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, various modifications or substitutions can be made without departing from the technical concept of the present invention, and all such modifications or substitutions should fall within the scope of protection of the present invention.

[0042] This embodiment uses Figure 2 Taking the particle arrangement shown as an example, this invention illustrates how to convert the original particle and contact information into the geometric boundary and topological connection results of a twin-cell system using the method of this invention. The method flow described in this embodiment is as follows: Figure 1 As shown. The method steps include:

[0043] S1. Construct a particle center coordinate table and a contact data table;

[0044] In this embodiment, firstly obtain Figure 2The particle center coordinates, contact point coordinates, and contact pair index data of the particle system shown are used as the original input information for constructing the twin-cell system. The particle center coordinates are denoted as... This is used to record the number of each particle and its center coordinates; the contact data table is denoted as... This is used to record the number of each contact point, the coordinates of each contact point, and the numbers of the two contact objects corresponding to each contact point. For particle-boundary contact, the contact objects also include boundary objects. After processing in this step, a unified original input data object is formed, providing basic data for subsequent geometric subdivision and cell construction.

[0045] This step establishes the basic relationships between particles and contact points. Particle center coordinates characterize particle positions, contact point coordinates characterize contact positions between particles or between particles and boundaries, and contact pair indices record the two contact objects corresponding to each contact point and are used to establish the relationship between contact points and particles. After processing in this step, the raw input data for subsequent geometric subdivision and cell construction is generated.

[0046] S2. Generate an initial set of triangular facets based on the contact data table, and construct an initial node coordinate table and an initial triangular facet vertex number table based on the initial set of triangular facets.

[0047] In this embodiment, a contact data table is used. All contact points are treated as a set of geometric vertices, and Delaunay triangulation is performed using the Bowyer-Watson algorithm to obtain an initial set of triangular facets covering the target region. Through this step, the original discrete contact points are organized into an interconnected triangular facet structure, thus forming the basic geometric partitioning result. After this step, the initial node coordinate table is obtained. and the initial triangular element vertex index table ,in, Used to record the node number and node coordinates corresponding to all contact points. This is used to record the vertex node indices corresponding to each initial triangular element. The global Delaunay triangulation result is as follows: Figure 3 As shown.

[0048] S3. Generate particle boundary polygons based on the particle center coordinate table and contact data table, and construct a particle boundary polygon vertex number table based on the particle boundary polygons;

[0049] In this embodiment, for Figure 2 For any particle in the particle arrangement shown, from the contact data table Extract all contact points associated with the particle, perform Delaunay triangulation on this group of contact points, and merge the generated triangular elements to form the coverage area of ​​the corresponding particle; further extract the outer contour of the coverage area to obtain the particle boundary polygon corresponding to the particle. The vertex indices of the particle boundary polygon are denoted as follows: This is used to record the vertex node numbers and their arrangement order of the polygons that constitute the boundaries of each particle. After this step, a coordinate table is formed that corresponds to the initial node coordinate table. and the initial triangular element vertex index table Corresponding particle boundary data object This serves as the geometric basis for subsequent region determination and segmentation correction.

[0050] S4. Perform region determination on all initial triangular elements in the initial triangular element set to obtain triangular elements that need to be segmented and corrected. Perform segmentation and correction on the triangular elements that need to be segmented and corrected to generate solid triangular elements and porous triangular elements. Merge the solid triangular elements and porous triangular elements to form solid elements and porous elements respectively.

[0051] In this embodiment, the initial triangular element is region-determined based on the contact object information of the contact points corresponding to the vertices of the initial triangular element and the geometric relationship between the initial triangular element and the particle boundary polygon. If the contact object numbers of the contact points corresponding to the three vertices of an initial triangular element all contain the same particle number, then the initial triangular element is determined to be a solid triangular element; if the contact object numbers of the contact points corresponding to the three vertices of an initial triangular element do not contain the same particle number, and the initial triangular element does not geometrically overlap with the internal region of any particle boundary polygon, then the initial triangular element is determined to be a porous triangular element; if the contact object numbers of the contact points corresponding to the three vertices of an initial triangular element do not contain the same particle number, and the initial triangular element geometrically overlaps with the internal region of at least one particle boundary polygon, then the initial triangular element is determined to be a triangular element that needs to be segmented and corrected.

[0052] For triangular facets requiring segmentation and correction, one or more sets of triangular facets that geometrically overlap with the same particle boundary polygon are first merged to form a polygon to be segmented. Then, the polygon to be segmented is segmented using the same particle boundary polygon to obtain solid region polygons located inside the same particle boundary polygon and porous region polygons located outside the same particle boundary polygon. Subsequently, triangulation is performed separately to generate solid triangular facets and porous triangular facets, and adjacent triangular facets in the same region are merged to form solid elements and porous elements, respectively. After this step, solid element sets are formed. and pore unit set , used to characterize the solid region units and porous region units in this embodiment. The region determination and segmentation correction process is as follows: Figure 4 As shown, the distribution results of the formed solid units and porous units are as follows: Figure 5 As shown.

[0053] After this step, a table of vertex numbers for solid elements and a table of vertex numbers for porous elements are formed, providing a basis for the regional elements in subsequent cell construction.

[0054] S5. Based on the pore center, the pore unit is divided into multiple pore triangular facets, and the pore triangular facets are merged with the solid unit to form a solid cell; a solid cell vertex index table is constructed based on the solid cell;

[0055] In this embodiment, a center point is defined for each pore element, and the pore element is divided into several triangular patches using the center point and the endpoints of each edge of the pore element boundary as vertices; the coordinates of the center point are added to the initial node coordinate table. Subsequently, for each solid element, the triangular facets corresponding to the common boundary from the adjacent porous elements that share a common boundary are incorporated into that solid element to form the corresponding solid cell. Through this step, a full-space solid cell system is obtained, composed of the local geometric relationships between the solid elements and their adjacent porous elements. The vertex numbers of the solid cell are denoted as... This is used to record the vertex sequence corresponding to the boundary of each solid cell. The process of dividing the pore unit is as follows: Figure 6 As shown.

[0056] After this step, a full-space solid cell system is obtained, and a table of solid cell vertex numbers is output.

[0057] S6. Based on the particle center, the solid unit is divided into multiple solid triangular facets, and the solid triangular facets are merged with the pore unit to form a pore cell; a pore cell vertex index table is constructed based on the pore cell.

[0058] In this embodiment, the solid element is divided into several triangular patches using the endpoints of the particle center and each edge of the solid element boundary as vertices; the particle center coordinates are added to the initial node coordinate table. Subsequently, for each pore element, the triangular facets corresponding to the common boundary from the adjacent solid elements that share a common boundary are incorporated into that pore element to form the corresponding pore cell. Through this step, a full-space pore cell system is obtained, composed of the pore element and the local geometric relationships of its adjacent solid elements. The vertex indices of the pore cell are denoted as follows: This step is used to record the vertex sequence corresponding to the boundary of each pore cell. After processing in this step, the full-space pore cell system is obtained, and a table of pore cell vertex numbers is output.

[0059] After processing S5 and S6, the geometric boundary structure of the binary cell system in this embodiment is completed. The constructed solid cell system and porous cell system are as follows: Figure 7 As shown.

[0060] S7. Extract the adjacency relationships between solid cells and between pore cells that have common contact points, and construct the adjacency table for solid cells and the adjacency table for pore cells.

[0061] In this embodiment, after obtaining the solid cell system and the porous cell system, the cell adjacency relationship is further extracted based on whether cells of the same type have common contact points. Two cells of the same type are determined to be adjacent if they have at least one common contact point; otherwise, they are determined not to be adjacent. This forms a solid cell adjacency table. Adjacency table of pore cells This is used to record the adjacency relationships between cells of the same type and characterize the topological associations between cells, thereby obtaining the two-cell network characterization results of the internal structure of granular materials. After this step, this embodiment finally obtains the solid cell vertex index table. 1. Pore Cell Vertex Number Table Solid cell adjacency table Adjacency table of pore cells Thus Figure 2 The original particle and contact information in the particle system shown is converted into a two-cell network data structure composed of cell boundaries and cell adjacency relationships.

[0062] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A method for characterizing the internal structure network of particulate materials based on interparticle contact, characterized in that, Includes the following steps: S1. Construct a particle center coordinate table and a contact data table; S2. Generate an initial set of triangular facets based on the contact data table, and construct an initial node coordinate table and an initial triangular facet vertex number table based on the initial set of triangular facets. S3. Generate particle boundary polygons based on the particle center coordinate table and the contact data table, and construct a particle boundary polygon vertex number table based on the particle boundary polygons; S4. Perform region determination on all initial triangular elements in the initial triangular element set to obtain triangular elements that need to be segmented and corrected. Perform segmentation and correction on the triangular elements that need to be segmented and corrected to generate solid triangular elements and porous triangular elements. The solid triangular facets and the porous triangular facets are respectively combined to form solid units and porous units; S5. Based on the pore center, the pore unit is divided into multiple pore triangular facets, and the pore triangular facets are merged with the solid unit to form a solid cell; a solid cell vertex index table is constructed based on the solid cell; S6. Based on the particle center, the solid unit is divided into multiple solid triangular facets, and the solid triangular facets are merged with the pore unit to form a pore cell; a pore cell vertex index table is constructed based on the pore cell. S7. Extract the adjacency relationships between solid cells and between pore cells that have common contact points, and construct the adjacency table for solid cells and the adjacency table for pore cells.

2. The method according to claim 1, characterized in that, The particle center coordinate table in step S1 is constructed by collecting the particle center coordinates. The particle center coordinate table records the number of each particle and its center coordinates. The contact data table is constructed by collecting the contact point coordinates and contact pair index data. The contact data table records the number of each contact point, the coordinates of each contact point, and the numbers of the two contact objects corresponding to each contact point.

3. The method according to claim 1, characterized in that, The construction of the initial triangular element set in step S2 is specifically as follows: taking all contact points in the contact data table as the geometric vertex set, performing Delaunay triangulation on the geometric vertex set using the Bowyer-Watson algorithm to generate the initial triangular element set; the initial node coordinate table records the node number and node coordinates corresponding to all contact points, and the initial triangular element vertex number table records the vertex node number corresponding to each initial triangular element.

4. The method according to claim 1, characterized in that, In step S3, the particle boundary polygon is generated based on the particle center coordinate table and the contact data table. Specifically, all contact points associated with any particle are extracted from the contact data table, and Delaunay triangulation is performed. The triangular elements generated by the triangulation are merged to form the coverage area corresponding to any particle. Then, the outer contour of the coverage area is extracted to generate the particle boundary polygon corresponding to any particle, and all particle boundary polygons corresponding to all particles are obtained.

5. The method according to claim 1, characterized in that, In step S3, a vertex index table for particle boundary polygons is constructed based on the particle boundary polygons. Specifically, the vertex index table for particle boundary polygons is constructed based on the vertex node indexes and arrangement order of all particle boundary polygons.

6. The method according to claim 1, characterized in that, In step S4, region determination is performed on all initial triangular facets in the initial triangular facet set to obtain the triangular facets that need to be segmented and corrected. Specifically: When the contact object numbers of the three vertices of an initial triangular element all contain the same particle number, the initial triangular element is determined to be a solid triangular element. When the contact object numbers of the three vertices of an initial triangular element do not contain the same particle number, and the initial triangular element does not geometrically overlap with the internal region of any particle boundary polygon, the initial triangular element is determined to be a pore triangular element. When the contact object numbers of the three vertices of an initial triangular element do not contain the same particle number, and the initial triangular element geometrically overlaps with the internal region of any particle boundary polygon, the initial triangular element is determined to be a triangular element that needs to be segmented and corrected.

7. The method according to claim 1, characterized in that, In step S4, the triangular facets that need to be segmented and corrected are segmented and corrected to generate solid triangular facets and porous triangular facets. Specifically: One or more sets of triangular facets that geometrically overlap with the boundary polygon of the same particle are merged to form a polygon to be segmented. The polygon to be segmented is divided using the same particle boundary polygon to obtain a solid region polygon located inside the same particle boundary polygon and a pore region polygon located outside the same particle boundary polygon. The solid region polygon and the pore region polygon are triangulated to generate solid triangular elements and pore triangular elements.

8. The method according to claim 1, characterized in that, In step S5, the porous unit is divided into multiple porous triangular facets, and the porous triangular facets are merged with adjacent solid units to form a solid cell. Specifically, the porous unit is divided into multiple porous triangular facets using the center point and the endpoints of each boundary side of the porous unit as vertices. For each solid unit, the porous triangular facets corresponding to the common boundary in the porous unit with which it shares a common boundary are incorporated into the solid unit to form the corresponding solid cell.

9. The method according to claim 1, characterized in that, In step S6, the solid unit is divided into multiple solid triangular facets, and the solid triangular facets are merged with adjacent pore units to form pore cells. Specifically, the solid unit is divided into multiple solid triangular facets using the center point and the endpoints of each boundary side of the solid unit as vertices. For each pore unit, the solid triangular facets corresponding to the common boundary in the solid units that share a common boundary with it are incorporated into the pore unit to form the corresponding pore cell.

10. The method according to claim 1, characterized in that, In step S7, the adjacency relationships between solid cells and between porous cells with common contact points are extracted respectively. Specifically, when two solid cells or two porous cells have at least one common contact point, they are determined to be adjacent; otherwise, they are determined not to be adjacent. The solid cell adjacency table and the porous cell adjacency table represent the topological adjacency relationships between cells of the same type.

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