A method and device for path planning of a continuous fiber periodic structure based on stacking

Abstract

The application discloses a kind of based on laminated continuous fiber periodic structure path planning method and device, the method includes: according to the configuration of the first preset rule to determine to select periodicity single cell structure;Based on single cell structure in design domain division unit, and based on all units in design domain to single cell structure is arranged and combined processing;Based on the connection relationship between the nodes of the configuration of all single cell structures in design domain is determined by preset minimum distance, and the adjacent matrix indicating node connection relationship is established;Based on adjacent matrix, initial node and traversal direction, according to the second preset rule is carried out path planning to obtain based on laminated continuous fiber periodic single cell structure path.The application can realize the path planning of periodic structure of complex single cell type composition and the periodic single cell structure of different single cell type combination, and combined with composite laminated idea to reduce the structural defects caused by fiber dislocation when 3D printing periodic structure.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology for continuous fiber reinforced composite materials, and in particular to a method and apparatus for planning the path of a continuous fiber periodic structure based on stacking. Background Technology

[0002] Due to their lightweight, high strength, and strong energy absorption capabilities, periodic unit cell structures are widely used as load-bearing components and energy absorbers in the form of sandwich structures and thin-walled structures, showing great application potential in many industrial fields such as aerospace, automotive, and construction. With the emergence of 3D printing continuous fiber composite material technology, many researchers have begun to study the design and path trajectory design of continuous fiber periodic unit cell structures.

[0003] Current research largely focuses on designing and printing path trajectories for single-type honeycomb structures, such as hexagons, rhombuses, rectangles, and circles, further improving the mechanical properties of the structures by changing the arrangement and orientation of continuous fibers. However, research on the design and path planning of periodic structures composed of complex unit cell types, as well as periodic unit cell structures composed of combinations of different unit cell types, remains lacking. When planning path paths for continuous fiber periodic structures, further exploration and research are needed to minimize structural defects caused by fiber dislocations while considering manufacturing constraints such as printing width and one-stroke design.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a method and apparatus for path planning of continuous fiber periodic structures based on stacked layers. This solves the problem in existing technologies where, while considering manufacturing constraints such as printing width and one-stroke design, path planning is performed on periodic structures composed of complex unit cell types and periodic unit cell structures composed of combinations of different unit cell types. Furthermore, it incorporates the concept of composite material stacking to reduce structural defects caused by fiber dislocations during 3D printing of periodic structures.

[0006] In a first aspect, embodiments of this application provide a path planning method for a continuous fiber periodic structure based on stacked layers, including:

[0007] The configuration of the periodic single-cell structure is determined according to the first preset rule;

[0008] The design domain is divided into units based on the size of the unit cell structure, and the unit cell structure is arranged and combined based on all units in the design domain.

[0009] Based on a preset minimum distance, the connection relationships between nodes of all unit cell configurations within the design domain are determined, and an adjacency matrix representing the node connection relationships is established.

[0010] Based on the adjacency matrix, initial nodes, and traversal direction, path planning is performed according to the second preset rule to obtain a continuous fiber periodic unit cell structure path based on stacking.

[0011] Preferably, the first preset rule includes:

[0012] The width of all sides in the unit cell structure is set to a fixed fiber spacing or an even multiple of the fixed fiber spacing;

[0013] The unit cell structure is an Eulerian diagram;

[0014] All nodes of the unit cell structure are interconnected after any combination.

[0015] Preferably, the division of units within the design domain based on the dimensions of the unit cell structure includes:

[0016] Determine the dimensions of the unit cell structure;

[0017] The design domain is divided into units based on the dimensions, and each unit is numbered.

[0018] Preferably, the process of arranging and combining the unit cell structure based on all units within the design domain includes:

[0019] Based on all units within the design domain, the unit cell structure is arranged and combined according to the exclusion checkerboard rule;

[0020] The connectivity of the arranged and combined unit cell structures is checked and repaired.

[0021] The arrangement and combination of the unit cell structures that have undergone the connectivity check and repair process are determined as the final arrangement and combination.

[0022] Preferably, the connectivity check and repair process for the arranged and combined unit cell structures includes:

[0023] Based on the arrangement and combination of the unit cell structure, the units of the unit cell structure are traversed to extract all adjacent units of the unit cell structure that fill the unit cell structure.

[0024] The surrounding space is divided into quadrant regions centered on the unit that fills the unit cell structure.

[0025] When three adjacent units in at least one quadrant region are all units filled with a single cell structure, the unit filled with the single cell structure is determined to satisfy connectivity; otherwise, the single cell structure is refilled into the unit, and connectivity check and repair are performed again.

[0026] Preferably, determining the connection relationships between nodes of all unit cell configurations within the design domain based on a preset minimum distance includes:

[0027] When the distance between nodes in a unit cell configuration is less than or equal to a preset distance, the nodes are determined to be connected.

[0028] The nodes are numbered, and an N×N adjacency matrix is ​​established based on the numbering, where N is a natural number;

[0029] When node i and node j are connected to each other, the elements in the i-th row and j-th column and the j-th row and i-th column of the adjacency matrix are set to 1.

[0030] When node i and node j are not connected to each other, the elements in the i-th row and j-th column and the j-th row and i-th column of the adjacency matrix are set to 0.

[0031] Preferably, the step of performing path planning based on the adjacency matrix, initial nodes, and traversal direction according to a second preset rule to obtain a continuous fiber periodic unit cell structure path based on stacking includes:

[0032] Based on the adjacency matrix, initial nodes, and traversal direction, the loop is inserted step by step using the Hilholz algorithm;

[0033] When a node is a multi-path intersection, the multi-path intersection is judged by an optimization strategy, and the path trajectory is determined based on the judged candidate nodes.

[0034] The optimization strategy includes:

[0035] Extract the node with the smallest angle change as the node to be traversed next;

[0036] Determine the position of the remaining node relative to the path of the next traversal node;

[0037] If the remaining node is not on the path of the preset next traversal node, then the next traversal node is taken as a path candidate node, and the optimization strategy is executed again.

[0038] If the remaining node is on one side of the path of the next traversal node, the optimization strategy is executed again.

[0039] Preferably, the step of performing path planning according to the second preset rule based on the adjacency matrix, the initial node, and the traversal direction to obtain a continuous fiber periodic unit cell structure path based on stacking further includes:

[0040] The unit cell structure is provided with defects, the defects including:

[0041] An intersection connects three nodes of three paths; and / or,

[0042] An intersection connects the four nodes of four paths.

[0043] Preferably, the method further includes:

[0044] Based on the node order of the path trajectory, all nodes are traversed to determine the number of defects in the unit cell structure.

[0045] The initial nodes and / or traversal direction of the path trajectory are adjusted to eliminate the defect;

[0046] When all the defects are eliminated and / or the number of traversals reaches the preset number, the traversal stops and the final path trajectory is obtained.

[0047] The final path trajectory is processed by layering to obtain the layered continuous fiber periodic unit cell structure path.

[0048] Secondly, embodiments of this application also provide a path planning device for a continuous fiber periodic structure based on stacked layers. The device includes a processor, a memory, and program instructions stored in the memory. When the program instructions are executed by the processor, they implement the path planning method for a continuous fiber periodic structure based on stacked layers as described above.

[0049] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0050] This application embodiment divides the design domain into units by selecting periodic unit cell structures, and then arranges and combines the unit cell structures and establishes an adjacency matrix through the division of units. Path planning is performed through the adjacency matrix, initial nodes, and traversal directions to obtain a path for a continuous fiber periodic unit cell structure based on stacking. This enables path planning for periodic structures composed of complex unit cell types and periodic unit cell structures composed of combinations of different unit cell types. Furthermore, it incorporates the concept of composite material stacking to reduce structural defects caused by fiber dislocations during 3D printing of periodic structures. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 A schematic flowchart of a path planning method for a continuous fiber periodic structure based on stacked layers, provided in an embodiment of this application;

[0053] Figure 2 The diagram illustrates a common filling configuration of 3D printed continuous fibers provided in the embodiments of this application as a periodic unit cell structure.

[0054] Figure 3 The following is another schematic diagram of a common filling configuration of 3D printed continuous fibers provided in the embodiments of this application as a periodic unit cell structure;

[0055] Figure 4 A flowchart illustrating the process of dividing a design domain into units based on a unit cell structure is provided for embodiments of this application.

[0056] Figure 5 A schematic flowchart illustrating the arrangement and combination of the unit cell structure based on the unit provided in this application embodiment;

[0057] Figure 6 A schematic diagram illustrating the process of performing connectivity checks and repairs on the arrangement and combination of unit cell structures, as provided in an embodiment of this application.

[0058] Figure 7 A schematic diagram illustrating the effect of periodic structures composed of two arrangements and combinations of unit cell structures provided in the embodiments of this application;

[0059] Figure 8 A schematic diagram illustrating the process of obtaining the connection relationships between nodes of all unit cell structures provided in this application embodiment;

[0060] Figure 9 This is a flowchart illustrating the path planning based on the adjacency matrix, initial node, and traversal direction according to the second preset rule, as provided in an embodiment of this application.

[0061] Figure 10 This is a schematic diagram illustrating the path planning effect provided in an embodiment of this application.

[0062] Figure 11 A schematic diagram illustrating the defect effects provided in the embodiments of this application;

[0063] Figure 12A flowchart illustrating the process of eliminating defects in a path trajectory based on defined defects, as provided in an embodiment of this application;

[0064] Figure 13 This is a schematic diagram of the clockwise trajectory of the upper vertex provided in an embodiment of this application;

[0065] Figure 14 This is a schematic diagram illustrating the clockwise printing effect of the top vertex in an embodiment of this application.

[0066] Figure 15 This is a schematic diagram of the counterclockwise trajectory of the upper vertex provided in an embodiment of this application;

[0067] Figure 16 This is a schematic diagram illustrating the counter-clockwise printing effect of the top vertex in an embodiment of this application.

[0068] Figure 17 This is a schematic diagram of the clockwise trajectory of the lower vertex provided in an embodiment of this application;

[0069] Figure 18 This is a schematic diagram illustrating the clockwise printing effect of the lower vertex in an embodiment of this application.

[0070] Figure 19 This is a schematic diagram of the counterclockwise trajectory of the lower vertex provided in an embodiment of this application;

[0071] Figure 20 This is a schematic diagram illustrating the counter-clockwise printing effect of the lower vertex in an embodiment of this application.

[0072] Figure 21 This is a schematic diagram illustrating the relationship between the number of defective nodes and the number of ply layers in an embodiment of this application.

[0073] Figure 22 This is a schematic diagram illustrating the printing effect provided in an embodiment of this application. Detailed Implementation

[0074] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0075] The following description of some technologies involved in the embodiments of this application is provided to aid understanding and should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, some descriptions of well-known functions and structures are omitted in the following description.

[0076] refer to Figure 1 As shown in the embodiments of this application, the path planning method for a continuous fiber periodic structure based on stacked layers includes:

[0077] S1. Determine the configuration of the periodic unit cell structure to be used according to the first preset rule.

[0078] In the embodiments of this application, the first preset rule includes: the width of all edges in the periodic unit cell structure is set to a fixed fiber spacing or an even multiple of the fixed fiber spacing; the periodic unit cell structure is designed to conform to the characteristics of an Euler graph, so that the number of edges connected to any node in the periodic unit cell structure is even; after any combination of periodic units cells, all nodes can be connected to each other, and the number of edges connected to the nodes is even.

[0079] In this embodiment, the periodic unit cell structure is a basic unit that can be repeated to form a larger structure. The edges in a periodic unit cell structure refer to the line segments or interfaces connecting the various parts of the unit cell. Each periodic unit cell structure is checked to ensure it conforms to the characteristics of an Eulerian graph, i.e., the number of edges connected to any node in the periodic unit cell structure is even. To this end, the periodic unit cell structure can be converted into a dot-line graph based on a fixed fiber spacing, all nodes in the structure are numbered, and an adjacency matrix between nodes is constructed. By analyzing the adjacency matrix, it is determined whether the degree of each node is even, thus confirming whether the periodic unit cell structure is an Eulerian graph. When selecting a periodic unit cell structure, the connectivity between units must be fully guaranteed. It must be ensured that after any combination of periodic unit cells, all nodes can be connected to each other, and the degree of all nodes in the combined structure remains even, satisfying the condition that the overall structure can be manufactured in one stroke. (Reference) Figure 2 and Figure 3 The diagram shown is a schematic representation of two common filling configurations of 3D printed continuous fibers provided in this embodiment as periodic unit cell structures. Figure 2 and Figure 3 All of them are periodic unit cell structures that satisfy the first preset rule.

[0080] S2. Divide the unit cell structure into units within the design domain based on the size of the unit cell structure, and arrange and combine the unit cell structure based on all units within the design domain.

[0081] In the embodiments of this application, to achieve controllable, predictable, and manufacturable 3D printed structural designs, it is necessary to divide the design domain into units based on the dimensions of the unit cell structure, thereby establishing a bridge from microscopic design to macroscopic manufacturing. In this embodiment, by dividing the design domain into units, a "skeleton" of arranged unit cell structures is established to ensure that the unit cells can fill the entire design domain neatly and without overlap. Furthermore, by placing unit cell structures with different properties (such as rigid unit cell structures, flexible unit cell structures, porous unit cell structures, etc.) in units in different regions, a gradual spatial distribution of material properties is achieved.

[0082] refer to Figure 4 As shown, when dividing the design domain into elements based on the dimensions of the unit cell structure, the following steps are followed:

[0083] S21. Determine the size of the unit cell structure.

[0084] S22. Divide the design domain into units based on the dimensions, and number the units.

[0085] In this embodiment, the design domain is divided into several identical units based on the size of the unit cell structure, each of which can be filled with the unit cell structure. Furthermore, to facilitate the management and calculation of the units, each unit is assigned a unique ID, such as (1,1), (1,2), (2,1)... In this way, the computer can accurately locate and manipulate each unit and know the unit cell structure filled in each unit.

[0086] refer to Figure 5 As shown, when arranging and combining the unit cell structure based on all units within the design domain, the following steps are performed:

[0087] S23. Based on all units within the design domain, arrange and combine the unit cell structure according to the exclusion checkerboard rule.

[0088] S24. Perform connectivity checks and repairs on the arranged and combined unit cell structures.

[0089] S25. The arrangement and combination of the unit cell structures that have undergone the connectivity check and repair process are determined as the final arrangement and combination.

[0090] In the embodiments of this application, after dividing the design domain into units, the unit cell structure that can be filled in each unit can be further determined according to design requirements. For example, according to the first preset rule mentioned above, various unit cell structures with different functions, such as A (very strong), B (relatively flexible), and C (lightweight and porous), are selected. When arranging and combining these unit cell structures, unit cell structure A can be filled in unit numbered (1,1), unit cell structure B can be filled in unit numbered (1,2), and unit cell structure A can also be filled in unit numbered (2,1), etc. In this embodiment, arranging and combining unit cell structures based on the units divided within the design domain allows each tiny area to be carefully designed during the 3D printing process, so that they can share the load and transfer heat in the optimal way, thereby achieving goals that traditional materials cannot reach, such as lightweight, high strength, and multifunctionality.

[0091] In this embodiment, the checkerboard phenomenon is essentially a drastic, periodic fluctuation in stiffness. When one element is very stiff, the adjacent element is very flexible, and then the next adjacent element is very stiff again, the force (stress) transmission path becomes unsmooth, concentrating at the interface between rigid and flexible elements. This stress concentration significantly reduces the overall strength, stiffness, and fatigue life of the structure, causing it to fail even below the design load.

[0092] Therefore, in the process of arranging and combining unit cell structures based on partitioning units, it is further necessary to perform checkerboard pattern removal on the arrangement and combination of unit cell structures. In one embodiment, checkerboard pattern removal is performed using density filtering. Specifically, a design variable (such as density, 0 represents empty, 1 represents solid) is defined for each cell. When calculating the physical properties of each cell, not only itself is considered, but also the weighted average of all neighboring cells within a certain radius. In another embodiment, checkerboard pattern removal is performed using sensitivity filtering. Specifically, in each optimization iteration, the sensitivity of each cell (the degree of influence of changing the density of the cell on performance) is calculated first. The sensitivity is then filtered and smoothed, and the filtered sensitivity is used to guide the update of the design variable, which can better maintain clear boundaries while avoiding checkerboard patterns. The above are only exemplary descriptions of checkerboard pattern removal. Based on the concept of this application, other methods such as projection methods, perimeter constraint methods, and image-based morphological operations for checkerboard pattern removal are all within the scope of protection of this application.

[0093] refer to Figure 6 As shown, after arranging and combining the unit cell structures, the connectivity of the arrangement and combination is further checked and repaired, following these steps:

[0094] S241. Based on the arrangement and combination of the unit cell structure, traverse the units of the unit cell structure and extract all adjacent units of the units that fill the unit cell structure.

[0095] S242. Divide the surrounding space into quadrant regions with the unit filling the unit cell structure as the center.

[0096] S243. When three adjacent units in at least one quadrant region are all units filled with a single cell structure, it is determined that the unit filled with the single cell structure satisfies connectivity; otherwise, the single cell structure is refilled into the unit, and connectivity check and repair processing is performed again.

[0097] In the embodiments of this application, after arranging and combining the unit cell structures based on the partitioning units, the filling of the unit cell structures of the partitioning units is completed. During connectivity checks, the units filled with unit cell structures are first traversed, and all adjacent units of the filled unit cell structure are extracted. Then, using the filled unit cell structure as the center, the surrounding space is divided into regions. For example, the surrounding space is divided into four quadrants: upper left, upper right, lower left, and lower right. If, within a quadrant region, the three specific units immediately adjacent to the central unit are all filled with unit cell structures, then the central unit is determined to have stable connectivity within that quadrant region. If the check finds that stable connectivity cannot be satisfied in any quadrant region, then the central unit is refilled with unit cell structures to re-connect it stably and firmly to the main structure. This process is repeated to obtain the final arrangement and combination of unit cell structures. Figure 7 As shown, this is a periodic structure composed of two types of unit cell structures arranged and combined, which satisfies the connectivity requirement.

[0098] S3. Determine the connection relationships between nodes of all unit cell configurations within the design domain based on a preset minimum distance, and establish an adjacency matrix representing the node connection relationships.

[0099] In the embodiments of this application, in order to facilitate subsequent planning and connectivity analysis of the continuous fiber periodic unit cell structure path, an adjacency matrix is ​​established by the connection relationship between the nodes of the unit cell structure configuration, thereby transforming the physical structure into a mathematical model that can be processed by a computer, so that the path planning and connectivity analysis can be completed by a computer.

[0100] refer to Figure 8 As shown, the following steps are followed when obtaining the connection relationships between nodes of all unit cell structures:

[0101] S31. When the distance between nodes is less than and / or equal to a preset distance, the nodes are determined to be connected.

[0102] S32. Number the nodes and establish an N×N adjacency matrix based on the numbers, where N is a natural number.

[0103] S33. When node i and node j are connected to each other, the value of the i-th row and j-th column and the j-th row and i-th column of the adjacency matrix are both 1.

[0104] S34. When node i and node j are not connected to each other, the values ​​of the i-th row and j-th column and the j-th row and i-th column of the adjacency matrix are both 0.

[0105] In the embodiments of this application, to determine the connection relationship between nodes, firstly, it is necessary to determine the minimum distance between nodes in all unit cell configurations. When the distance between nodes is less than or equal to the minimum distance, it is determined that the two nodes are interconnected. Further, based on the minimum distance, all nodes within the design domain are traversed to find all nodes that satisfy the interconnection relationship and are numbered. In one embodiment, each node is assigned a unique ID, for example: 1, 2, 3, ..., N, where N represents the total number of nodes, calculated using the following formula:

[0106]

[0107] Where L is the length of the design domain and W is the width of the design domain. d min The minimum distance.

[0108] Furthermore, an N×N adjacency matrix is ​​established based on this number. The adjacency matrix is ​​then assigned values ​​based on the connection relationships between nodes. In this embodiment, when node i and node j are connected, the corresponding values ​​in the i-th row and j-th column of the adjacency matrix are both 1; when node i and node j are not connected, the corresponding values ​​in the i-th row and j-th column of the adjacency matrix are both 0. This process of establishing and assigning values ​​to the adjacency matrix is ​​repeated sequentially. In one embodiment, assuming there are 4 nodes (N=4), the connection relationship is: 1 connects to 2, 2 connects to 3, and 3 connects to 4. The adjacency matrix is ​​shown in Table 1.

[0109] Table 1 is a 4×4 adjacency matrix.

[0110]

[0111] In this embodiment, by establishing an N×N adjacency matrix, when the computer performs tasks such as analyzing the connectivity of the structure, finding the shortest path, and calculating reliability, it no longer needs to understand complex geometric shapes. It only needs to look at this table composed of 0s and 1s to apply various graph theory algorithms for processing.

[0112] S4. Based on the adjacency matrix, initial nodes, and traversal direction, perform path planning according to the second preset rule to obtain a continuous fiber periodic unit cell structure path based on stacking.

[0113] In the embodiments of this application, after arranging and combining the unit cell structure and establishing the corresponding adjacency matrix based on the above steps, path planning begins based on the adjacency matrix, the initial node set, and the traversal direction.

[0114] refer to Figure 9 As shown, the steps for path planning based on the adjacency matrix, initial nodes, and traversal direction according to the second preset rule include:

[0115] S41. Based on the adjacency matrix, initial nodes, and traversal direction, the loop is inserted step by step using the Hierholzer algorithm.

[0116] S42. When a node is a multi-path intersection point, the multi-path intersection point is judged by an optimization strategy, and the path trajectory planning is determined based on the judged candidate nodes.

[0117] In this embodiment, the optimization strategy includes: extracting the node with the smallest angle change as the next traversal node; determining the position of the remaining node relative to the path of the next traversal node. Specifically, if the remaining node is on one side of the path of the next traversal node, the optimization strategy is executed again; if the remaining node is not on one side of the path of the next traversal node, the next traversal node is selected as a path candidate node, and the optimization strategy is executed again.

[0118] refer to Figure 10 As shown in the embodiments of this application, when starting path planning, the established adjacency matrix, the set initial nodes, and the traversal direction are used as inputs. The Hierholzer algorithm is used to progressively insert loops until all edges form a single-stroke path. In this embodiment, considering the impact of intersecting paths on structural mechanics, when a node is a multi-path intersection, a judgment is applied to the multi-path intersection, selecting the node with the smallest change in path angle as the trajectory, i.e., the next traversal node. The path angle is calculated using the following formula:

[0119]

[0120] in, The path angle for the next traversed node. This refers to the node currently being traversed. This refers to the node that was traversed in the previous step. For the next step of traversing the nodes, i This refers to the node's number. In this embodiment, the next step is to traverse the nodes. It can be It can also be or .

[0121] In this embodiment, after determining the next traversal node from the path perspective, the remaining nodes are evaluated. Specifically, the evaluation criteria are determined using vector products. Determine the positions of the remaining nodes:

[0122]

[0123] Among them, if If the remaining nodes are on one side of the path, then that point is excluded as the next trajectory point. Then, the point with the smallest angle change is judged, and intersecting paths can be formed in order to form path trajectory planning.

[0124] In the embodiments of this application, to ensure the continuity and smoothness of the fibers during printing and to achieve optimal mechanical properties, it is necessary to classify printing defects according to the way the fibers converge at the intersections, and to provide an optimal path repair scheme for each type. In this embodiment, the defect type is defined according to the number of fiber paths connected to an intersection after node deduplication. The defects include: three nodes at an intersection connecting three fiber paths and four nodes at an intersection connecting four fiber paths, as referenced. Figure 11 As shown. One solution for repairing a three-node defect is to ensure the continuity of the transverse and longitudinal fibers. That is, when planning the path, the fibers passing through the node should be able to continue smoothly forward without interruption at that node, thereby enhancing the overall integrity and mechanical performance of the structure. Another solution for repairing a four-node defect is to establish a coordinate system centered on the intersection point, calculate the direction angle of each connecting path, and sort all the angles, for example, by size. From the sorted directions, two paths with an angle difference of 180 degrees are connected to form a straight line, and the other two are connected to form another straight line. This creates two straight intersecting paths at the intersection point.

[0125] refer to Figure 12 As shown in the embodiments of this application, the steps for eliminating defects in the path trajectory based on defined defects are as follows:

[0126] S44. Traverse all nodes based on the node order of the path trajectory to determine the number of defects in the unit cell structure.

[0127] S45. Adjust the initial node and / or traversal direction of the path trajectory to eliminate the defect.

[0128] S46. When all the defects are eliminated and / or the number of traversals reaches a preset number, the traversal is stopped, and the final path trajectory is obtained.

[0129] S47. Perform a layering process on the path trajectory to obtain the layered continuous fiber periodic unit cell structure path.

[0130] In the embodiments of this application, after setting the defects of the continuous fiber periodic unit cell structure based on the foregoing content, all nodes in the planned path trajectory are traversed based on the defects to search for the above-mentioned defects, and the total number of nodes with defects is counted. Further, using the path trajectory node order as input, all nodes are traversed to search for the above-mentioned types of defects, and the number of defect points is counted. A new path trajectory is formed through the initial node and traversal direction, and the defects in the nodes are detected again. The process terminates when the defects are completely eliminated or when the traversal count reaches the maximum number of loop traversals. The resulting multi-path trajectory determines the overall path trajectory of the structure through layering.

[0131] In one embodiment of this application, Figures 13-20 As shown, this is a multi-layer trajectory diagram determined based on the above method. The multi-track stacking obtained according to the node positions and traversal directions can effectively reduce or even eliminate defects. The relationship between the number of defective nodes and the number of layers is as follows: Figure 21 As shown. In this embodiment, the path trajectory point information of each layer is converted into G-code and imported into a continuous fiber 3D printer for printing. The printing result is as follows. Figure 22 As shown.

[0132] Secondly, embodiments of this application also provide a path planning device for a continuous fiber periodic structure based on stacked layers. The device includes a processor, a memory, and program instructions stored in the memory. When the program instructions are executed by the processor, they implement the path planning method for a continuous fiber periodic structure based on stacked layers as described above.

[0133] This application also provides a non-volatile computer-readable storage medium storing a computer program or instructions thereon, which, when executed, enables the implementation of the layered continuous fiber periodic structure path planning method as described in this application.

[0134] In summary, this application proposes a path planning design for periodic structures composed of different unit cell configurations. During the initial design, connectivity judgment is used to suppress the checkerboard phenomenon, ensuring that the overall periodic unit cell structure can be manufactured in one stroke. By progressively inserting nodes in the Hierholzer algorithm and imposing constraints to preferentially form intersecting trajectories, the mechanical performance of the overall structure is improved. By defining node defect types, adjusting the initial nodes and traversal directions, and combining the concept of composite material stacking, structural defects caused by fiber dislocations during 3D printing of periodic structures are reduced.

[0135] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A path planning method for a continuous fiber periodic structure based on stacked layers, characterized in that, include: The configuration of the periodic single-cell structure is determined according to the first preset rule; The design domain is divided into units based on the size of the unit cell structure, and the unit cell structure is arranged and combined based on all units in the design domain. Based on a preset minimum distance, the connection relationships between nodes of all unit cell configurations within the design domain are determined, and an adjacency matrix representing the node connection relationships is established. Based on the adjacency matrix, initial nodes, and traversal direction, path planning is performed according to the second preset rule to obtain a continuous fiber periodic unit cell structure path based on stacking. The step of obtaining a path for a continuous fiber periodic unit cell structure based on stacked layers by performing path planning according to the second preset rule based on the adjacency matrix, initial nodes, and traversal direction includes: Based on the adjacency matrix, initial nodes, and traversal direction, the loop is inserted step by step using the Hilholz algorithm; When a node is a multi-path intersection, the multi-path intersection is judged by an optimization strategy, and the path trajectory is determined based on the judged candidate nodes. The optimization strategy includes: Extract the node with the smallest angle change as the node to be traversed next; Determine the position of the remaining node relative to the path of the next traversal node; If the remaining node is not on the path of the next traversal node, then the next traversal node is taken as a path candidate node, and the optimization strategy is executed again. If the remaining node is on one side of the path of the next traversed node, then the optimization strategy is executed again; The step of performing path planning based on the adjacency matrix, initial nodes, and traversal direction according to the second preset rule to obtain a continuous fiber periodic unit cell structure path based on stacking also includes: The unit cell structure is provided with defects, the defects including: An intersection connects three nodes of three paths; and / or, An intersection connects the four nodes of four paths; Also includes: Based on the node order of the path trajectory, all nodes are traversed to determine the number of defects in the unit cell structure. The initial nodes and / or traversal direction of the path trajectory are adjusted to eliminate the defect; When all the defects are eliminated and / or the number of traversals reaches the preset number, the traversal stops and the final path trajectory is obtained. The final path trajectory is processed by layering to obtain the layered continuous fiber periodic unit cell structure path.

2. The path planning method for continuous fiber periodic structures based on stacked layers according to claim 1, characterized in that, The first preset rule includes: The width of all sides in the unit cell structure is set to the fixed fiber spacing or an even multiple of the fixed fiber spacing; The unit cell structure is an Eulerian diagram; All nodes of the unit cell structure are interconnected after any combination.

3. The path planning method for continuous fiber periodic structures based on stacked layers according to claim 1, characterized in that, The division of units within the design domain based on the dimensions of the unit cell structure includes: Determine the dimensions of the unit cell structure; The design domain is divided into units based on the dimensions, and each unit is numbered.

4. The path planning method for continuous fiber periodic structures based on stacked layers according to claim 3, characterized in that, The process of arranging and combining the unit cell structure based on all units within the design domain includes: Based on all units within the design domain, the unit cell structure is arranged and combined according to the exclusion checkerboard rule; The connectivity of the arranged and combined unit cell structures is checked and repaired. The arrangement and combination of the unit cell structures that have undergone the connectivity check and repair process are determined as the final arrangement and combination.

5. The path planning method for continuous fiber periodic structures based on stacked layers according to claim 4, characterized in that, The connectivity check and repair process for the arranged and combined unit cell structures includes: Based on the arrangement and combination of the unit cell structure, the units of the unit cell structure are traversed to extract all adjacent units of the unit cell structure that fill the unit cell structure. The surrounding space is divided into quadrant regions centered on the unit that fills the unit cell structure. When three adjacent units in at least one quadrant region are all units filled with a single cell structure, the unit filled with the single cell structure is determined to satisfy connectivity; otherwise, the single cell structure is refilled into the unit, and connectivity check and repair are performed again.

6. The path planning method for continuous fiber periodic structures based on stacked layers according to claim 1, characterized in that, The process of determining the connection relationships between nodes of all unit cell configurations within the design domain based on a preset minimum distance, and establishing an adjacency matrix representing the node connection relationships, includes: When the distance between nodes in a unit cell configuration is less than or equal to a preset distance, the nodes are determined to be connected. The nodes are numbered, and an N×N adjacency matrix is ​​established based on the numbering, where N is a natural number; When node i and node j are connected to each other, the elements in the i-th row and j-th column and the j-th row and i-th column of the adjacency matrix are set to 1. When node i and node j are not connected to each other, the elements in the i-th row and j-th column and the j-th row and i-th column of the adjacency matrix are set to 0.

7. A path planning device for a continuous fiber periodic structure based on stacked layers, characterized in that, The device includes a processor, a memory, and program instructions stored in the memory, wherein when the program instructions are executed by the processor, they implement the path planning method for a continuous fiber periodic structure based on stacking as described in any one of claims 1 to 6.

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