F-Rep-based random lattice structure modeling method and device

Abstract

The invention belongs to the related technical field of CAD model expression, and discloses a random lattice structure modeling method and device based on F-Rep, and the method comprises the following steps: S1, obtaining vertex data and unit information of tetrahedral mesh units; s2, based on the local topological relation in the tetrahedral mesh units, performing topological reconstruction on the connection relation between the tetrahedral mesh units by adopting a half-surface coded mesh topological data structure; s3, under the modeling coordinate system, the truss type primitives are converted into the radius of a node circle and geometric control parameters of a conic curve tangent to the corresponding circle, and then an expression of the truss type primitives is obtained; and S4, directly constructing an implicit expression function of the truss primitives in the global coordinate system based on the geometric control parameters of the truss primitives so as to obtain the implicit expression function of each truss primitive in the global coordinate system, and realizing the function expression of the random lattice structure model. According to the method, the compactness of a data structure is improved, and the memory overhead is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field related to CAD model expression, and more specifically, relates to a random lattice structure modeling method and device based on F-Rep. Background Art

[0002] Lattice structures, which have both functional and structural characteristics, are widely used in the design of major equipment such as aerospace due to their mechanical properties such as light weight, high specific strength / rigidity, and unique multifunctional properties such as load-bearing, stealth, and drag reduction. Random lattice structures based on Delaunay triangulation often show enhanced mechanical properties and are therefore used in energy absorption or impact resistance. As a type of heterogeneous multi-scale structure, random lattice structures have the largest design space and degrees of freedom, and in theory are the most fully exploited type of multi-scale structural performance optimization potential.

[0003] This type of structure usually has complex geometric features at multiple scales, and the structure is highly non-periodic. Existing CAD systems based on B-Rep expression can hardly complete the design of such complex structures in terms of shape and scale based on geometric description alone. Using standard CAD software to design lattice structures is very inefficient and time-consuming, and the obtained models are prone to errors. On the other hand, although voxel modeling is easy to implement and highly robust, the memory overhead of its model and the discrete defects of the modeling method itself cannot be ignored. Like voxel modeling, direct modeling using triangular patches will also result in inaccurate geometric representation and excessive memory overhead, and these two indicators are often contradictory. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a random lattice structure modeling method and device based on F-Rep, which aims to solve the problems of low modeling efficiency and high storage overhead in the existing modeling methods when establishing lattice structure models.

[0005] To achieve the above object, according to one aspect of the present invention, a random lattice structure modeling method based on F-Rep is provided, and the modeling method comprises the following steps:

[0006] S1, by performing Delaunay triangulation on the macroscopic design domain of the random lattice structure, the vertex data and unit information of the tetrahedral mesh unit are obtained;

[0007] S2, based on the unit information, the three-layer topological elements of the tetrahedral mesh unit, namely, body, half-edge, and vertex, are explicitly stored and implicitly expressed, and the connection relationship between the tetrahedral mesh units is topologically reconstructed using a half-face-encoded mesh topological data structure based on the local topological relationship inside the tetrahedral mesh unit;

[0008] S3, in the modeling coordinate system, the truss-like primitives are transformed into the radius of the node circle and the geometric control parameters of the conic curve tangent to the corresponding circle, and then the expressions of the truss-like primitives are obtained to realize the unified implicit function representation of the truss-like primitives of the tetrahedral grid unit in the local coordinate system; wherein the truss-like primitives include cylindrical truss primitives, cone truss primitives and quadratic surface primitives; the geometric control parameters include t, r1 and r2, r1 and r2 are the radii of the two node circles respectively, and t represents the shape parameters of the truss between the two node circles;

[0009] S4, based on the geometric control parameters of the truss primitive, directly construct the implicit expression function of the truss primitive in the global coordinate system, and then obtain the implicit expression function of each truss primitive in the global coordinate system according to the grid topology data structure, realizing the functional expression of the random lattice structure model.

[0010] Furthermore, in the half-face encoded grid topology data structure, every two tetrahedral grid units share one face. Referring to the definition of the half-edge data structure: this face is divided into two half-faces, each half-face is defined by a tuple consisting of the serial number of the corresponding tetrahedral unit and the local index on the unit where the half-face is located, and the tuple of the half-face is encoded as a 32-bit unsigned integer, the last three bits store the local index of the half-face, and the remaining bits store the index of the tetrahedral grid unit.

[0011] Furthermore, the macroscopic design domain of the random lattice structure is subjected to Delaunay triangulation, and the vertex data P and unit information C are obtained as follows:

[0012]

[0013] In the formula, m is the number of vertices, n is the number of tetrahedral units, Represents the four vertex indices of the u-th unit; i = 1, 2, 3, 4.

[0014] Furthermore, step S2 includes the following sub-steps:

[0015] S21: Define and store the volume-half-face-vertex three-layer topological elements on the tetrahedral mesh unit;

[0016] S22, every two tetrahedral mesh units share a face, refer to the definition of the half-edge data structure: divide this face into two half-faces, each half-face is defined by a tuple consisting of the serial number of the corresponding tetrahedral unit and the local index of the unit where the half-face is located, and encode the half-face tuple as a 32-bit unsigned integer, the last three bits store the local index of the half-face, and the remaining bits store the index of the tetrahedral mesh unit;

[0017] S23: Construct topological relationships between tetrahedral mesh elements.

[0018] Furthermore, in S23, two intermediate mappings are first established by traversing all half-faces: v2hfs and v2adj. v2hfs records the mapping between the maximum index vertex and the half-face on each half-face; v2adj records the corresponding mapping between the remaining vertices and the half-face. Secondly, each half-face is traversed again to obtain the maximum vertex index as the key, and the remaining vertex indices are used as additional information of the key. Furthermore, the matching partner half-face is searched in the set of half-faces with the same key value, thereby constructing a mapping relationship between the half-faces.

[0019] Furthermore, step S3 includes the following sub-steps:

[0020] S31: The local modeling coordinate system is defined on the xOy plane. The two node circles and the truss primitives correspond to three basic functions in the local modeling coordinate system: the conic section equations of the circles at (-1, 0) and (1, 0) and the truss primitives tangent to the circles are:

[0021]

[0022] Where r1 and r2 are the radii of the two node circles. According to the tangency condition, equations (2) and (3) are combined with (1) to calculate the two parameters c and d of equation (1);

[0023] S32: Define the third circle with its center at (0, 0) and radius The third control parameter t is introduced to make the third circle tangent to the truss, and the third parameter a is calculated by using equation (1);

[0024] S33: The conic section equations corresponding to the three geometric control parameters r1, r2 and t define the outer contour of the truss element, and a three-dimensional truss element located in the local modeling coordinate system is generated by rotating around the X-axis; among them, the conic section equations corresponding to the three geometric control parameters r1, r2 and t are the function expressions of the truss element.

[0025] Furthermore, when the truss primitive corresponds to an ellipsoidal surface, assuming that the center point of the ellipsoidal surface is o, the three symmetry axes are u, v, and w, where u represents the rotation axis of the quadratic curve, and the semi-axis lengths are m, n, and n, respectively, then the surface equation is expressed as:

[0026]

[0027] Furthermore, when the truss primitive corresponds to a single-leaf hyperboloid, the surface equation is constructed as:

[0028]

[0029] When the quadratic curve degenerates into a straight line, the truss primitives correspond to the cylindrical surface and the conical surface respectively; assuming that the radius of the cylindrical surface is r, a point on the axis is o, and the axis direction is n, the distance from any point x on the cylindrical surface to the axis is r, and the cylindrical surface equation is expressed as:

[0030] (xo) T (I-nn T )(xo)=r 2

[0031] Assume that the vertex of the cone is o, the semi-vertex angle is θ, the axis direction is n, the generatrix direction is l, and the cosine value of the angle between the generatrix and the axis is cosθ=l T n, the equation of the cone surface is obtained from the geometric relationship:

[0032]

[0033] The present invention also provides a random lattice structure modeling system based on F-Rep, the system comprising a memory and a processor, the memory storing a computer program, and the processor executing the random lattice structure modeling method based on F-Rep as described above when executing the computer program.

[0034] The present invention also provides a computer-readable storage medium, which stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the F-Rep-based random lattice structure modeling method as described above.

[0035] In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

[0036] 1. The truss unit is expressed by implicit functions. Compared with the cumbersome and complex topological transformation, especially the rotation transformation based on the Euler matrix, the proposed method simplifies the calculation process and improves the calculation accuracy and efficiency. At the same time, the connection relationship between tetrahedral grid units is topologically reconstructed by using the half-face coded grid topological data structure. This encoding method can accommodate about 500 million units. While maintaining the data volume, it improves the compactness of the data structure and greatly reduces the memory overhead.

[0037] 2. The grid topology data structure based on half-face encoding constructs the adjacency relationship between adjacent tetrahedral grid units. As a connection between the macroscopic design domain and the microscopic truss element, it can effectively support information transmission and exchange between the two scales.

[0038] 3. While accurately defining the geometric shape of the lattice object, the topological relationship between the truss elements is also constructed, which has the characteristics of high degree of automation, stability and reliability, wide range of applicability, strong feasibility and high computational efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of a random lattice structure modeling method based on F-Rep provided by the present invention;

[0040] Figure 2 It is a schematic diagram of the GE engine bracket used to represent the macroscopic design domain of the random lattice structure;

[0041] Figure 3 It is a schematic diagram of the macroscopic design domain expressed by discrete tetrahedral mesh elements after Delaunay triangulation;

[0042] Figure 4 (a), (b), and (c) are schematic diagrams of the definition of topological elements of the mesh topological data structure of half-face coding;

[0043] Figure 5 It is a schematic diagram showing the mapping relationship between the half-surfaces after topological reconstruction;

[0044] Figure 6 It is a schematic diagram of the truss-like primitive in the local two-dimensional modeling coordinate system;

[0045] Figure 7 (a), (b), (c), (d), and (e) are schematic diagrams of the models of truss-like primitives formed in three-dimensional space after rotating around an axis;

[0046] Figure 8 It is a complex random lattice structure design diagram expressed based on the F-Rep model. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] See also Figure 1 The present invention provides a random lattice structure modeling method based on F-Rep, which mainly includes the following steps:

[0049] S1, by performing Delaunay triangulation on the macroscopic design domain of the random lattice structure, the vertex data and unit information of the tetrahedral mesh unit are obtained.

[0050] The macroscopic design domain of the random lattice structure can be any shape with complex geometric shapes. It is generally stored in general CAD formats such as IGES and STEP. The three-dimensional complex design domain is Delaunay triangulated to obtain vertex data P and unit information C as shown below:

[0051]

[0052] In the formula, m is the number of vertices, n is the number of tetrahedral units, Represents the four vertex indices of the u-th cell.

[0053] In one embodiment, see Figure 2 and Figure 3 In this example, the macroscopic design domain of the random lattice structure is selected as the GE engine bracket model, and the Delaunay meshing process is completed. After statistics, a total of 28077 vertices and 18075 tetrahedral mesh elements are generated.

[0054] S2, according to the unit information, the three-layer topological elements of the tetrahedral mesh unit, namely the body, half-edge and vertex, are explicitly stored and implicitly expressed respectively, and the connection relationship between the tetrahedral mesh units is topologically reconstructed using the half-face encoded mesh topological data structure based on the local topological relationship inside the tetrahedral mesh unit.

[0055] In order to establish the adjacency relationship between adjacent tetrahedral grid cells, a half-face coded grid topology data structure is introduced to organize discrete grid data. The specific steps are as follows:

[0056] S21: Define and store the volume-half-face-vertex three-layer topological elements on the tetrahedral mesh unit: the vertex index starts from 0, and the unit index starts from 1. For each unit, it is agreed that the storage relationship of the four vertices on the tetrahedral mesh unit follows the CGNS rule.

[0057] S22: Every two tetrahedral mesh units share a face. Refer to the definition of the half-edge data structure: divide this face into two half-faces. Each half-face is defined by a tuple consisting of the serial number of the corresponding tetrahedral unit and the local index of the unit where the half-face is located. The half-face tuple is encoded as a 32-bit unsigned integer. The last three bits store the local index of the half-face, and the remaining bits store the index of the tetrahedral mesh unit. This encoding method can accommodate about 500 million units. While maintaining the data volume, it improves the compactness of the data structure and greatly reduces memory overhead.

[0058] S23: Constructing the topological relationship between tetrahedral mesh units, the key lies in constructing the mapping relationship between half-faces. First, by traversing all half-faces, two intermediate mappings are established: v2hfs and v2adj. v2hfs records the mapping between the maximum index vertex and the half-face on each half-face; v2adj records the mapping between the corresponding remaining vertices and half-faces. Secondly, traverse each half-face again to obtain the maximum vertex index as the key, and use the remaining vertex indexes as additional information of the key. Secondly, find the matching partner half-face in the set of half-faces with the same key value, so as to construct the mapping relationship between the half-faces.

[0059] In one embodiment, see Figure 4 and Figure 5 , taking a set of adjacent tetrahedral units as an example, Figure 4 The definition of the underlying topological elements is presented in detail, including the explicit storage of vertices and cells and the rules for half-face encoding. Figure 5 Taking a finite set of adjacent tetrahedral mesh units as an example, the mapping relationship between adjacent half-faces established based on half-face encoded mesh topology data is demonstrated.

[0060] S3, in the modeling coordinate system, transforms the truss-like primitives into the radius of the node circle and the geometric control parameters of the conic curve tangent to the corresponding circle, and then obtains the expression of the truss-like primitives to realize the unified representation of implicit functions of the truss-like primitives of the tetrahedral grid unit in the local coordinate system; wherein, the truss-like primitives include cylindrical truss primitives, cone truss primitives and quadratic surface primitives; the geometric control parameters include t, r1 and r2, r1 and r2 are the radii of the two node circles respectively, and t represents the shape parameters of the truss between the two node circles.

[0061] The truss primitive expressed based on F-Rep consists of two node circles at the vertices and a truss primitive composed of conic curves as outlines. The specific steps are as follows:

[0062] S31: The local modeling coordinate system is defined on the xOy plane. The two node circles and the truss primitives correspond to three basic functions in the local modeling coordinate system: the circles at (-1, 0) and (1, 0) and the conic section equations of the truss primitives tangent to the circles, as shown below:

[0063]

[0064] Where r1 and r2 are the radii of the two node circles. According to the tangency condition, equations (2) and (3) are combined with equation (1) to calculate the two parameters c and d of equation (1).

[0065] S32: Define the third circle with its center at (0, 0) and radius The third control parameter t is introduced to make the third circle tangent to the truss, and the third parameter a is calculated by solving equation (1).

[0066] S33: The conic section equations corresponding to the three geometric control parameters r1, r2 and t define the outer contour of the truss element. By rotating around the X-axis, a three-dimensional truss element located in the local modeling coordinate system can be generated; among them, the conic section equations corresponding to the three geometric control parameters r1, r2 and t are the function expressions of the truss element.

[0067] In one embodiment, see Figure 6 and Figure 7 , step S3 includes the following sub-steps:

[0068] S31: The local modeling coordinate system is defined on the xOy plane. The three primitives correspond to the three basic functions in the local modeling coordinate system: the conic section equations of the circles at (-1, 0) and (1, 0) and the truss primitives tangent to the circles, Figure 6 Shows the geometric shape definition of the primitive in the local modeling coordinate system.

[0069] S32: Define the third circle with its center at (0, 0) and radius The third control parameter t is introduced to make the third circle tangent to the truss element, and the third parameter a is calculated by solving equation (1).

[0070] S33: The conic section equation controlled by the three parameters r1, r2 and t defines the outer contour of the truss primitive. By rotating around the X-axis, the three-dimensional truss primitive contour in the local modeling coordinate system can be generated. Figure 7 The three-dimensional primitive shapes after rotation around the X-axis are shown, including four types of truss primitive shapes.

[0071] S4, based on the geometric control parameters of the truss primitive, directly construct the implicit expression function of the truss primitive in the global coordinate system, and then obtain the implicit expression function of each truss primitive in the global coordinate system according to the grid topology data structure, realizing the functional expression of the random lattice structure model.

[0072] According to the different types of truss primitives, truss primitives can be represented as elliptical primitives, single-leaf hyperbolic primitives, and traditional cylindrical primitives and cone primitives. The position of the truss primitive in space depends on the coordinates of the two endpoints of the edge in the grid. According to the geometric control parameters of the truss primitive in S3, the coordinates of the center point and the semi-major axis length of the truss primitive in the global coordinate system are calculated. In order to transform the implicit function of the truss primitive in the local modeling coordinate system to the global coordinate system, the specific steps are as follows:

[0073] S41: Implicit functions of two spherical primitives located at the vertices of the grid line, calculated directly from the coordinates and radius of the vertices;

[0074] S42: When the truss primitive corresponds to an ellipsoid, assuming that the center point of the ellipsoid is o, the three symmetry axes are u, v, and w, where u represents the rotation axis of the quadratic curve, and the semi-axis lengths are m, n, and n, respectively. The surface equation is expressed as:

[0075]

[0076] Similarly, when the truss primitive corresponds to a single-leaf hyperboloid, the surface equation is constructed as:

[0077]

[0078] When the quadratic curve degenerates into a straight line, the truss primitives correspond to cylindrical and conical surfaces respectively.

[0079] Assume that the radius of the cylinder is r, the point on the axis is o, and the direction of the axis is n. According to the distance from any point x on the cylinder to the axis is r, the equation of the cylinder is expressed as:

[0080] (xo) T (I-nn T )(xo)=r 2

[0081] Assume that the vertex of the cone is o, the semi-vertex angle is θ, the axis direction is n, the generatrix direction is l, and the cosine value of the angle between the generatrix and the axis is cosθ=l T n, the equation of the cone surface can be obtained from the geometric relationship:

[0082]

[0083] In one embodiment, the implicit expression of the truss primitive in the global coordinate system includes the following steps:

[0084] S41: Implicit functions of two spherical primitives located at the vertices of the grid line, calculated directly by the coordinates of the vertices and the radius. In this example, the coordinates of the primitive nodes are specified by the grid vertices, and 1 / 8 of the shortest distance of each vertex's 1-neighborhood is selected as the radius.

[0085] S42: All truss primitives are specified as cone primitives, and the implicit function equation of the truss primitive in the global coordinate system is expressed as:

[0086]

[0087] S5: According to the grid topology data structure, each truss primitive is implicitly modeled in the global coordinate system to realize the functional expression of the random lattice structure CAD model.

[0088] See also Figure 8This is the modeling result of the final random lattice structure. After testing, the F-Rep model construction time is only 59.07s.

[0089] The present invention also provides a random lattice structure modeling system based on F-Rep, the system comprising a memory and a processor, the memory storing a computer program, and the processor executing the random lattice structure modeling method based on F-Rep as described above when executing the computer program.

[0090] The present invention also provides a computer-readable storage medium, which stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the F-Rep-based random lattice structure modeling method as described above.

[0091] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A random lattice structure modeling method based on F-Rep, characterized in that: The modeling method comprises the following steps: S1, by performing Delaunay triangulation on the macroscopic design domain of the random lattice structure, the vertex data and unit information of the tetrahedral mesh unit are obtained; S2, based on the unit information, the three-layer topological elements of the tetrahedral mesh unit, namely, body, half-edge, and vertex, are explicitly stored and implicitly expressed, and the connection relationship between the tetrahedral mesh units is topologically reconstructed using a half-face-encoded mesh topological data structure based on the local topological relationship inside the tetrahedral mesh unit; S3, in the modeling coordinate system, the truss-like primitives are transformed into the radius of the node circle and the geometric control parameters of the conic curve tangent to the corresponding circle, and then the expressions of the truss-like primitives are obtained to realize the unified implicit function representation of the truss-like primitives of the tetrahedral grid unit in the local coordinate system; wherein the truss-like primitives include cylindrical truss primitives, cone truss primitives and quadratic surface primitives; the geometric control parameters include t, r1 and r2, r1 and r2 are the radii of the two node circles respectively, and t represents the shape parameters of the truss between the two node circles; S4, based on the geometric control parameters of the truss primitive, directly construct the implicit expression function of the truss primitive in the global coordinate system, and then obtain the implicit expression function of each truss primitive in the global coordinate system according to the grid topology data structure, realizing the functional expression of the random lattice structure model.

2. The random lattice structure modeling method based on F-Rep according to claim 1, characterized in that: In the half-face encoded grid topology data structure, every two tetrahedral grid units share one face. Refer to the definition of the half-edge data structure: this face is divided into two half-faces. Each half-face is defined by a tuple consisting of the serial number of the corresponding tetrahedral unit and the local index of the unit where the half-face is located. The tuple of the half-face is encoded as a 32-bit unsigned integer, the last three bits store the local index of the half-face, and the remaining bits store the index of the tetrahedral grid unit.

3. The random lattice structure modeling method based on F-Rep according to claim 1, characterized in that: Perform Delaunay triangulation on the macroscopic design domain of the random lattice structure, and obtain vertex data P and unit information C respectively: Where m is the number of vertices, n is the number of tetrahedral units, {N i (u) } represents the four vertex indices of the u-th unit; i = 1, 2, 3, 4.

4. The random lattice structure modeling method based on F-Rep according to claim 1, characterized in that: Step S2 includes the following sub-steps: S21: Define and store the volume-half-face-vertex three-layer topological elements on the tetrahedral mesh unit; S22, every two tetrahedral mesh units share a face, refer to the definition of the half-edge data structure: divide this face into two half-faces, each half-face is defined by a tuple consisting of the serial number of the corresponding tetrahedral unit and the local index of the unit where the half-face is located, and encode the half-face tuple as a 32-bit unsigned integer, the last three bits store the local index of the half-face, and the remaining bits store the index of the tetrahedral mesh unit; S23: Construct topological relationships between tetrahedral mesh elements.

5. The random lattice structure modeling method based on F-Rep according to claim 4, characterized in that: In S23, two intermediate mappings are first established by traversing all half-faces: v2hfs and v2adj. v2hfs records the mapping between the maximum index vertex and the half-face on each half-face; v2adj records the mapping between the corresponding remaining vertices and half-faces. Secondly, each half-face is traversed again to obtain the maximum vertex index as the key, and the remaining vertex indices are used as additional information of the key. Furthermore, the matching partner half-face is searched in the set of half-faces with the same key value, thereby constructing a mapping relationship between the half-faces.

6. The random lattice structure modeling method based on F-Rep according to claim 1, characterized in that: Step S3 includes the following sub-steps: S31: The local modeling coordinate system is defined on the xOy plane. The two node circles and the truss primitives correspond to three basic functions in the local modeling coordinate system: the conic section equations of the circles at (-1, 0) and (1, 0) and the truss primitives tangent to the circles are: Where r1 and r2 are the radii of the two node circles respectively. According to the tangency condition, equations (2) and (3) are combined with equation (1) to calculate the two parameters c and d of equation (1). S32: Define the third circle with its center at (0, 0) and radius The third control parameter t is introduced to make the third circle tangent to the truss, and the third parameter a is calculated by using equation (1); S33: The conic section equations corresponding to the three geometric control parameters r1, r2 and t define the outer contour of the truss element, and a three-dimensional truss element located in the local modeling coordinate system is generated by rotating around the X-axis; among them, the conic section equations corresponding to the three geometric control parameters r1, r2 and t are the function expressions of the truss element.

7. The random lattice structure modeling method based on F-Rep according to any one of claims 1 to 6, characterized in that: When the truss primitive corresponds to an ellipsoid, assuming that the center point of the ellipsoid is o, the three symmetry axes are u, v, and w, where u represents the rotation axis of the quadratic curve, and the semi-axis lengths are m, n, and n, respectively. The surface equation is expressed as:

8. The random lattice structure modeling method based on F-Rep according to claim 7, characterized in that: When the truss primitive corresponds to a single-leaf hyperboloid, the surface equation is constructed as: When the quadratic curve degenerates into a straight line, the truss primitives correspond to the cylindrical surface and the conical surface respectively; assuming that the radius of the cylindrical surface is r, a point on the axis is o, and the axis direction is n, the distance from any point x on the cylindrical surface to the axis is r, and the cylindrical surface equation is expressed as: (xo) T (I-nn T )(xo)=r 2 Assume that the vertex of the cone is o, the semi-vertex angle is θ, the axis direction is n, the generatrix direction is l, and the cosine value of the angle between the generatrix and the axis is cosθ=l T n, the equation of the cone surface is obtained from the geometric relationship:

9. A random lattice structure modeling system based on F-Rep, characterized in that: The system includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the F-Rep-based random lattice structure modeling method according to any one of claims 1 to 8 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores machine-executable instructions, and when the machine-executable instructions are called and executed by the processor, the machine-executable instructions prompt the processor to implement the F-Rep-based random lattice structure modeling method described in any one of claims 1-8.

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