A method for generating random granular particles considering the boundary of three-dimensional granular particle morphology

Abstract

The application discloses a randomization method for generating gravel particles considering the three-dimensional gravel particle shape boundary, determines pre-generated gravel particle gradation, obtains the equivalent particle diameter, equivalent volume and mass proportion of the gravel particles in each size interval, divides the mass proportion of the gravel particles in each size interval by the equivalent volume value, and obtains the ratio of the number of the gravel particles in each size interval; according to the total number of the pre-generated gravel particles, the number of the pre-generated gravel particles in each size interval, i.e. the sampling frequency, is obtained; the upper and lower limit values of the particle diameter of each size interval are taken as the sampling condition, and random sampling is performed in each size interval according to the sampling frequency; the three-dimensional boundary profile of the randomization gravel particle is determined based on the three-dimensional boundary coordinates obtained through the random sampling, the three-dimensional shape of the randomization gravel particle is generated by importing a drawing software, and the randomization gravel particle is generated in a DEM software by using the three-dimensional shapes of all the randomization gravel particles.

Description

Technical Field

[0001] This invention belongs to the field of discrete element simulation technology, and relates to a randomized method for generating gravel particles that considers the morphological boundaries of three-dimensional gravel particles. Background Technology

[0002] Natural gravel particles vary in shape and are generally considered brittle. Studies on natural gravel particles, such as deformation and crushing, often require extensive experimentation to fully account for the randomness of their physical properties. To reduce experimental costs and time, numerical simulation has become a commonly used research method. The shape of gravel particles significantly influences the crushing results; therefore, accurately simulating particle morphology is a crucial step in discrete element method (DEM) simulation. Some researchers use the generation of random gravel particle clusters for simulation, but this makes it difficult to account for the randomness of particle shape. Other scholars have used CT scans of single or multiple fragments of gravel for simulation. However, scanning single fragments can only generate a single shape, and scanning multiple fragments would be too labor-intensive, resulting in excessive initial work. Another approach involves generating clusters of gravel with a single shape and then randomly deleting smaller fragments from these clusters. However, this method, while generating different shapes by deleting surface fragments, can also result in the deletion of smaller fragments within the cluster. Deleting too many internal fragments can affect the strength of the gravel and the crushing process. Alternatively, some scholars have used spherical harmonic functions to construct Laplace equations for simulation. While this allows for the creation of randomized gravel particle shapes by changing parameters, it also increases the difficulty of randomization. Summary of the Invention

[0003] The purpose of this invention is to provide a randomized crushed stone particle generation method that considers the morphological boundaries of three-dimensional crushed stone particles, so as to solve the problem that existing randomized crushed stone particle generation methods cannot easily and quickly generate multiple randomized crushed stone particles.

[0004] The technical solution adopted in this embodiment of the invention is: a randomized method for generating gravel particles considering the morphological boundaries of three-dimensional gravel particles, which is carried out according to the following steps:

[0005] Step S1: Determine the pre-generated crushed stone particle size distribution to obtain the equivalent particle size, equivalent volume, and mass percentage of crushed stone particles in each size range.

[0006] Step S2: The ratio of the mass percentage of crushed stone particles in each size range to the equivalent volume is the ratio of the number of crushed stone particles in each size range. Then, based on the total number of crushed stone particles to be generated and the ratio of the number of crushed stone particles in each size range, the number of crushed stone particles to be generated in each size range is obtained.

[0007] Step S3: Use the upper and lower limits of particle size in each size range as sampling conditions, and use the number of pre-generated crushed stone particles in each size range as the number of samplings. Under the sampling conditions, randomly sample the three-dimensional boundary coordinates of each random crushed stone particle in each size range.

[0008] Step S4: Determine the three-dimensional boundary contour of the randomized crushed stone particles based on the three-dimensional boundary coordinates obtained from each random sampling, and then import the three-dimensional boundary contour into drawing software to generate the three-dimensional shape of the randomized crushed stone particles.

[0009] Step S5: Based on the pre-generated crushed stone particle size distribution, use the three-dimensional shape of all randomized crushed stone particles to generate randomized crushed stone particles that match the crushed stone particle size distribution in the DEM software.

[0010] Furthermore, in step S3, under sampling conditions, the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) of each random crushed stone particle within each size range are randomly sampled. A three-dimensional coordinate system is established with the center of the pre-generated random crushed stone particle as the coordinate circle. x1 is the coordinate value of the pre-generated random crushed stone particle intersecting with the positive x-axis, x2 is the coordinate value of the pre-generated random crushed stone particle intersecting with the negative x-axis, y1 is the coordinate value of the pre-generated random crushed stone particle intersecting with the positive y-axis, y2 is the coordinate value of the pre-generated random crushed stone particle intersecting with the negative y-axis, z1 is the coordinate value of the pre-generated random crushed stone particle intersecting with the positive z-axis, and z2 is the coordinate value of the pre-generated random crushed stone particle intersecting with the negative z-axis.

[0011] Furthermore, in step S3, the upper and lower limits of particle size for each size range are used as sampling conditions. This means that in the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) of each random crushed stone particle, the value of x1-x2 is greater than the lower limit of particle size for the corresponding size range and less than its upper limit; the value of y1-y2 is greater than the lower limit of particle size for the corresponding size range and less than its upper limit; the value of z1-z2 is greater than the lower limit of particle size for the corresponding size range and less than its upper limit; and the absolute values ​​of x1, x2, y1, y2, z1, and z2 are greater than the lower limit of particle size for the corresponding size range and less than its upper limit.

[0012] Furthermore, in step S4, for each randomly sampled 3D boundary coordinate (x1, x2, y1, y2, z1, z2), connect x1, y1, x2, y2 to determine an intermediate plane. Connect x1, z1, x2 and y1, z1, y2 respectively to obtain two boundary lines above the intermediate plane. Connect x1, z2, x2 and y1, z2, y2 respectively to obtain two boundary lines below the intermediate plane, thus obtaining the 3D boundary contour of the randomized gravel particles. Then, import the 3D boundary contour of the randomized gravel particles into drawing software, generate surfaces based on the boundary lines, and the resulting 3D sphere is the 3D shape of the randomized gravel particles. Export the 3D shape of the randomized gravel particles in STL format.

[0013] Furthermore, in step S5, the particle size distribution of the crushed stone is set in the DEM software, and the STL file of the three-dimensional shape of the randomized crushed stone particles generated in step S4 is imported to generate randomized crushed stone particles that match the particle size distribution.

[0014] The beneficial effects of this invention are: no complex preliminary work such as CT scanning is required, nor is it necessary to first generate gravel particle clusters and then randomly delete small gravel particles from the gravel particle clusters to simulate the shape of gravel particles. Therefore, it will not affect the strength of gravel particles. When simulating three-dimensional boundary conditions, it can fully consider the randomness of gravel particle morphology under natural conditions. It can randomly generate gravel particle shapes of corresponding sizes and matching the gravel particle gradation in each interval of the gravel particle gradation. The method is simple, has low computational load, and can quickly generate a pre-generated number of gravel particle shapes at once. It solves the problem that existing randomized gravel particle generation methods cannot easily and quickly generate multiple randomized gravel particles. Attached Figure Description

[0015] 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.

[0016] Figure 1 This is a schematic diagram of the three-dimensional boundary coordinates of the crushed stone particles obtained by random sampling in each embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the three-dimensional boundary contour of the randomized crushed stone particles generated in an embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of the three-dimensional shape of the randomized crushed stone particles generated in an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the geometric shape of the randomized crushed stone particles generated in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] This embodiment provides a randomized method for generating gravel particles that considers the morphological boundaries of three-dimensional gravel particles, including:

[0022] Step S1: Determine the pre-generated crushed stone particle gradation to obtain the equivalent particle size Ri, equivalent volume Vi, and mass percentage mi (%) of crushed stone particles in each size range. Ri is the equivalent particle size of crushed stone particles in the i-th size range, Vi is the equivalent volume of crushed stone particles in the i-th size range, and mi is the mass percentage (%) of crushed stone particles in the i-th size range, i.e., the proportion of the mass of crushed stone particles in the i-th size range to the total mass of all crushed stone particles, as shown in Table 1.

[0023] Table 1. Equivalent particle size, equivalent volume, and mass percentage of crushed stone particles within each size range.

[0024] Crushed stone particle size distribution Equivalent particle size equivalent volume Percentage of crushed stone particles in the interval d1~d2 R1=(d1+d2) / 2 V1 = (4 / 3) * π * R1^3 m1 d2~d3 R2=(d2+d3) / 2 V2=(4 / 3)*π*R2^3 m2 d3~d4 R3=(d3+d4) / 2 V3=(4 / 3)*π*R3^3 m3 d4~d5 R4 = (d4 + d5) / 2 V4=(4 / 3)*π*R4^3 m4

[0025] Step S2: Since the density of the crushed stone particles is equal, the mass ratio of crushed stone particles in each size range is equivalent to the mass of crushed stone particles in each size range. Therefore, the ratio of the mass ratio mi of crushed stone particles in each size range to the equivalent volume Vi is the ratio of the number of crushed stone particles in each size range. Then, based on the total number of pre-generated crushed stone particles T and the ratio of the number of crushed stone particles in each size range, the number ni of pre-generated crushed stone particles in each size range is obtained, as shown in Table 2.

[0026] Table 2. Number of pre-generated crushed stone particles within each size range

[0027]

[0028] Step S3: Using the upper and lower limits of particle size for each size range as sampling conditions, and the number of pre-generated crushed stone particles within each size range as the sampling number, randomly sample the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) of each random crushed stone particle within each size range under the sampling conditions. Figure 1As shown, a three-dimensional coordinate system is established with the center of the pre-generated random crushed stone particles as the coordinate circle. x1 is the coordinate value of the pre-generated random crushed stone particles intersecting with the positive x-axis, x2 is the coordinate value of the pre-generated random crushed stone particles intersecting with the negative x-axis, y1 is the coordinate value of the pre-generated random crushed stone particles intersecting with the positive y-axis, y2 is the coordinate value of the pre-generated random crushed stone particles intersecting with the negative y-axis, z1 is the coordinate value of the pre-generated random crushed stone particles intersecting with the positive z-axis, and z2 is the coordinate value of the pre-generated random crushed stone particles intersecting with the negative z-axis.

[0029] Using the upper and lower limits of particle size for each size range as sampling conditions, the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) of each random crushed stone particle are defined as follows: the value of x1-x2 is greater than the lower limit of particle size for the corresponding size range and less than its upper limit; the value of y1-y2 is greater than the lower limit of particle size for the corresponding size range and less than its upper limit; the value of z1-z2 is greater than the lower limit of particle size for the corresponding size range and less than its upper limit; and the absolute values ​​of x1, x2, y1, y2, z1, and z2 are greater than the lower limit of particle size for the corresponding size range and less than its upper limit, as shown in Table 3.

[0030] Table 3 Sampling conditions for each size range

[0031] Crushed stone particle size distribution Sampling conditions d1~d2 d1 < x1 - x2 < d2, d1 < y1 - y2 < d2, d1 < z1 - z2 < d2; d1 < the absolute values of x1, x2, y1, y2, z1, z2 < d2 d2~d3 d2 < x1 - x2 < d3, d2 < y1 - y2 < d3, d2 < z1 - z2 < d3; d2 < the absolute values of x1, x2, y1, y2, z1, z2 < d3 d3~d4 d3 < x1 - x2 < d4, d3 < y1 - y2 < d4, d3 < z1 - z2 < d4; d3 < the absolute values of x1, x2, y1, y2, z1, z2 < d4 d4~d5 d4 < x1 - x2 < d5, d4 < y1 - y2 < d5, d4 < z1 - z2 < d5; d4 < the absolute values of x1, x2, y1, y2, z1, z2 < d5

[0032] Step S4: Determine the three-dimensional boundary contour of the randomized crushed stone particles based on the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) obtained from each random sampling, and then import the three-dimensional boundary contour into drawing software to generate the three-dimensional shape of the randomized crushed stone particles.

[0033] For each randomly sampled 3D boundary coordinate (x1, x2, y1, y2, z1, z2), connecting x1, y1, x2, and y2 defines an intermediate plane. Connecting x1, z1, x2, and y1, z1, and y2 yields two boundary lines above the intermediate plane. Connecting x1, z2, x2, and y1, z2, and y2 yields two boundary lines below the intermediate plane, thus obtaining the 3D boundary profile of the randomized gravel particles, as shown below. Figure 2 As shown; then the 3D boundary contour of the randomized gravel particles is imported into drawing software, and surfaces are generated based on the boundary lines. The resulting 3D sphere is the 3D shape of the randomized gravel particles, as shown. Figure 3 As shown, the three-dimensional shape of the randomized gravel particles is exported in STL format.

[0034] Step S5: Based on the pre-generated crushed stone particle size distribution, use the three-dimensional shape of all randomized crushed stone particles to generate randomized crushed stone particles that match the crushed stone particle size distribution in the DEM software.

[0035] In DEM software (Digital Elevation Modeling software), set the aggregate particle size distribution, import the generated STL file containing the 3D shape of randomized aggregate particles, and generate randomized aggregate particles that match the aggregate particle size distribution. The shape of the randomized aggregate particles is as follows: Figure 4 As shown in Table 4, the three-dimensional boundary coordinates of all gravel particles obtained by random sampling in each size range represent the morphology of gravel particles in the corresponding size range. The gravel particles in each size range are uniformly distributed within that size range.

[0036] Table 4. Gravel particle distribution for each size range

[0037]

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A randomization method of generating three-dimensional granular particles considering the boundary of granular particle morphology, characterized by, The following steps are performed: Step S1, determine the pre-generated gravel particle size distribution, obtain the equivalent particle size, equivalent volume and mass proportion of the gravel particles in each size interval; Step S2, the mass proportion of the gravel particles in each size interval is divided by the value obtained by dividing the equivalent volume, and the ratio of the number of gravel particles in each size interval is obtained, and then the total number of pre-generated gravel particles and the ratio of the number of gravel particles in each size interval are obtained. Step S3, the upper and lower limit values of the particle size of each size interval are taken as the sampling condition, and the number of pre-generated gravel particles in each size interval is taken as the sampling times, and the three-dimensional boundary coordinates of each random gravel particle in each size interval are randomly sampled under the sampling condition; Step S4, determine the three-dimensional boundary profile of the randomized gravel particle based on the three-dimensional boundary coordinates obtained by each random sampling, and then import the three-dimensional boundary profile into the drawing software to generate the three-dimensional shape of the randomized gravel particle; Step S5, based on the pre-generated gravel particle size distribution, the three-dimensional shape of all randomized gravel particles is used to generate randomized gravel particles matching the gravel particle size distribution in the DEM software.

2. The randomization aggregate particle generation method considering a three-dimensional aggregate particle morphology boundary according to claim 1, characterized by, In step S3, the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) of each random gravel particle in each size interval are randomly sampled under the sampling condition, the particle core of the pre-generated random gravel particle is taken as the coordinate point to establish a three-dimensional coordinate system, x1 is the coordinate value of the pre-generated random gravel particle intersecting the positive axis of the x-axis, x2 is the coordinate value of the pre-generated random gravel particle intersecting the negative axis of the x-axis, y1 is the coordinate value of the pre-generated random gravel particle intersecting the positive axis of the y-axis, y2 is the coordinate value of the pre-generated random gravel particle intersecting the negative axis of the y-axis, z1 is the coordinate value of the pre-generated random gravel particle intersecting the positive axis of the z-axis, and z2 is the coordinate value of the pre-generated random gravel particle intersecting the negative axis of the z-axis.

3. The randomization aggregate particle generation method considering a three-dimensional aggregate particle morphology boundary according to claim 1, characterized by, In step S3, the upper and lower limit values of the particle size of each size interval are taken as the sampling condition, which limits the values of x1-x2, y1-y2 and z1-z2 in the three-dimensional boundary coordinates (x1, x2, y1, y2, z1, z2) of each random gravel particle to be greater than the lower limit value of the particle size of the corresponding size interval and less than the upper limit value of the particle size, and the absolute values of x1, x2, y1, y2, z1 and z2 are greater than the lower limit value of the particle size of the corresponding size interval and less than the upper limit value of the particle size.

4. The randomization aggregate particle generation method considering a three-dimensional aggregate particle morphology boundary according to claim 1, wherein, In step S4, for each three-dimensional boundary coordinate (x1, x2, y1, y2, z1, z2) obtained by random sampling, an intermediate plane is determined by connecting x1, y1, x2, y2, two boundary lines above the intermediate plane are obtained by connecting x1, z1, x2, y1, z1, y2 respectively, and two boundary lines below the intermediate plane are obtained by connecting x1, z2, x2, y1, z2, y2 respectively, to obtain the three-dimensional boundary contour of the randomized gravel particle; then the three-dimensional boundary contour of the randomized gravel particle is imported into a drawing software, a surface is generated according to the boundary line, the obtained three-dimensional sphere is the three-dimensional shape of the randomized gravel particle, and the three-dimensional shape of the randomized gravel particle is exported in stl format.

5. The randomization aggregate particle generation method considering the three-dimensional aggregate particle morphology boundary according to any one of claims 1 to 4, characterized by, In step S5, the gravel particle gradation is set in the DEM software, the stl file of the three-dimensional shape of the randomized gravel particle generated in step S4 is imported, and the randomized gravel particle matching the gravel particle gradation is generated.

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