CN114734640B - Printing path generation method, computer equipment and storage medium - Google Patents

Printing path generation method, computer equipment and storage medium Download PDF

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CN114734640B
CN114734640B CN202210429202.2A CN202210429202A CN114734640B CN 114734640 B CN114734640 B CN 114734640B CN 202210429202 A CN202210429202 A CN 202210429202A CN 114734640 B CN114734640 B CN 114734640B
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triangular
partition
stress
patches
combined
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CN114734640A (en
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姚远
张航
马英鑫
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University of Shanghai for Science and Technology
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University of Shanghai for Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/30—Auxiliary operations or equipment
    • B29C64/386—Data acquisition or data processing for additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/118—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using filamentary material being melted, e.g. fused deposition modelling [FDM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y50/00—Data acquisition or data processing for additive manufacturing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Optics & Photonics (AREA)
  • Complex Calculations (AREA)
  • Management, Administration, Business Operations System, And Electronic Commerce (AREA)

Abstract

The invention provides a printing path generating method, which comprises the following steps: s3, performing triangular division on the 2D tangential plane to divide the 2D tangential plane into a plurality of triangular patches; s4, acquiring a combined stress tensor of the triangular surface patch after acquiring the stress tensor of the triangular surface patch node in the 2D tangential plane according to the stress tensor of the unit node calculated by the finite element so as to acquire the magnitude of a combined main stress field and the direction of the combined main stress field of the combined stress tensor, thereby acquiring the combined main stress field of the triangular surface patch; and S5, clustering the triangular patches to generate partition outlines, and acquiring the combined main stress field direction of each partition according to the combined main stress field of the triangular patches, so as to determine the filling direction of each partition and generate a printing path. The printing path generation method, the calculator equipment and the storage medium can obviously enhance the strength of the FFF process printing piece and improve the practicability of the whole process.

Description

Printing path generation method, computer equipment and storage medium
Technical Field
The invention is mainly applied to the field of additive manufacturing, and particularly relates to a printing path generation method, computer equipment and a storage medium.
Background
Because of the low cost of the fused filament fabrication (Fused Filament Fabrication, FFF) process equipment, convenient handling, and low cost of printed materials, it is now the most widely used process in additive manufacturing (Additive Manufacturing, AM) technology. The printing device mainly uses a printing nozzle to heat, uses a roller to feed polymer wires into a nozzle, and then uses layer-by-layer accumulation to print.
While the strength of a workpiece manufactured by FFF processes is affected by many process parameters and path planning factors, such as layer thickness, nozzle diameter, fill pitch, printing temperature, printing speed, different polymer materials, extrusion rates of materials, fill strategy, etc. The existence of these influencing factors makes it difficult to directly use the FFF process for manufacturing structural members and carriers, thereby restricting further development of the FFF process.
Disclosure of Invention
The invention aims to provide a printing path generation method, computer equipment and a storage medium, which can obviously enhance the strength of an FFF process printing piece and improve the practicability of the whole process.
The invention provides a printing path generation method, which comprises the following steps: s1, obtaining a stress tensor of a unit node calculated by an STL model, a layer height and a finite element; s2, slicing the 3D model according to the STL model and the layer thickness to obtain a 2D tangential plane; s3, performing triangular division on the 2D tangential plane so as to divide the 2D tangential plane into a plurality of triangular patches; s4, acquiring the combined stress tensor of the triangular patch after acquiring the stress tensor of the triangular patch node in the 2D tangential plane according to the stress tensor of the unit node calculated by the finite element so as to acquire the magnitude of the combined main stress field and the direction of the combined main stress field of the combined stress tensor, thereby acquiring the combined main stress field of the triangular patch; and S5, clustering the triangular patches to generate partition outlines, and acquiring the main stress field closing direction of each partition according to the main stress field closing of the triangular patches, so as to determine the filling direction of each partition and generate a printing path.
In one embodiment, step S4 includes: acquiring a stress tensor of a triangular node in the triangular patch; the stress tensors of the triangular nodes are combined to obtain the combined stress tensors of the triangular patches; and calculating the principal stress field of the triangular patch according to the principal stress tensor of the triangular patch.
In an embodiment, the obtaining the stress tensor of the triangle node in the triangle patch includes: mapping the spatial position of the triangular node in the triangular patch to a corresponding three-dimensional finite element; determining tetrahedrons of triangular nodes in the triangular patches in the three-dimensional finite element; and according to the tetrahedron, obtaining the stress tensor interpolation of the finite element nodes in the three-dimensional finite element, and calculating the stress tensor of the triangular nodes in the triangular patch.
In one embodiment, the step of determining, in the three-dimensional finite element, a tetrahedron to which a triangle node in the triangle patch belongs includes: searching tetrahedrons around the target points in the triangular patches according to a nearest field searching algorithm; traversing tetrahedrons around the target point to obtain tetrahedrons surrounding the target point.
In one embodiment, the step of obtaining the stress tensor interpolation of the finite element nodes in the three-dimensional finite element according to the belonging tetrahedron, and calculating the stress tensor of the triangle nodes in the triangular patch includes: taking a volume coordinate as a coefficient of the stress tensor interpolation, wherein the volume coordinate comprises the ratio of the volume formed by the target point and four faces of the tetrahedron surrounding the target point to the volume of the tetrahedron surrounding the target point; and acquiring the stress tensor of the target point according to the coefficient and the corresponding finite element node.
In one embodiment, the step S5 includes: s51, obtaining a partition iteration reference direction; s52, placing the triangular patches into corresponding subareas according to the principle that the directions are similar and the main stress field combining direction of the triangular patches and the subarea iteration reference direction are adopted; s53, calculating the reference direction of each subarea according to the combined principal stress field direction of the triangular patches in each subarea; s54, judging whether the maximum value of the absolute value of the difference value between the reference direction of each partition and the iterative reference direction of the corresponding partition is smaller than a preset value; if not, the step proceeds to step S55: updating the corresponding partition iteration reference direction according to the reference direction of each partition; returning to the step S52, according to the main stress field closing direction of the triangular patches and the partition iteration reference direction, putting the triangular patches into corresponding partitions according to the principle that the directions are similar; if the value is smaller than the preset value, the step S56 is entered: judging whether the number of triangular patches in the partition is larger than a threshold value or not; if not, the process proceeds to step S57: filtering out cluster partitions with the triangular patches less than a threshold value, and updating the number of the partitions; returning to the step S51, obtaining a partition iteration reference direction; if the threshold value is greater, the process proceeds to step S58: according to a clustering principle, putting triangular patches into corresponding subareas so as to obtain the combined principal stress field direction information of all the triangular patches in each subarea, and updating the reference direction of the corresponding subarea according to the combined principal stress field direction information of all the triangular patches in each subarea; s59, generating partition outlines according to triangular patch information in the corresponding clustering partitions, and determining printing paths according to the filling direction of each partition.
In one embodiment, the clustering principle in step S58 includes: the triangular patches clustered together are adjacent to each other, and the angular difference between the principal stress field direction of the triangular patches clustered together and the reference direction of the partition is within a preset range.
The invention also provides a computer device comprising a memory and a processor, said memory storing a computer program, characterized in that the processor implements the steps of the above method when executing said computer program.
The invention also provides a computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor realizes the steps of the above method.
According to the printing path generation method, the computer equipment and the storage medium, after the stress tensor of the triangular patch node in the 2D tangential plane is obtained according to the stress tensor of the unit node calculated by the finite element, the resultant stress tensor of the triangular patch is obtained to obtain the size of the resultant main stress field and the direction of the resultant main stress field of the resultant stress tensor, so that the resultant main stress field of the triangular patch is obtained, the triangular patches are clustered to generate the subarea profile, and then the resultant main stress field direction of each subarea is obtained according to the resultant main stress field of the triangular patch, so that the filling direction of each subarea is determined to generate the printing path.
Drawings
Fig. 1 is a flow chart of a print path generating method in an embodiment.
Fig. 2 is a schematic diagram of a uniform slice in an embodiment.
Fig. 3 is a schematic diagram of a 2D tangential plane after triangulating according to an embodiment.
Fig. 4 (a), 4 (b), and 4 (c) are schematic diagrams of stress field calculation of planar triangular patches in an embodiment.
FIG. 5 is a schematic diagram of a planar triangular patch stress field in one embodiment.
FIG. 6 is a flow diagram of clustering in one embodiment.
FIG. 7 is a schematic diagram of generating a partition contour in an embodiment.
FIG. 8 is a schematic diagram of a partition profile generated in one embodiment.
FIG. 9 is an overall print path based on zones in one embodiment.
Detailed Description
Preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings:
fig. 1 is a flow chart of a print path generating method according to an embodiment, and as shown in the figure, the steps are as follows:
s1: obtaining a stress tensor of a unit node calculated by an STL model, a layer height and a finite element;
s2: slicing the 3D model according to the STL model and the layer thickness to obtain a 2D tangential plane;
s3: triangulating the 2D tangent plane to divide the 2D tangent plane into a plurality of triangular patches;
s4: acquiring the combined stress tensor of the triangular patch after acquiring the stress tensor of the triangular patch node in the 2D tangential plane according to the stress tensor of the unit node calculated by the finite element so as to acquire the size of the combined main stress field and the direction of the main stress field of the combined stress tensor, thereby acquiring the combined main stress field of the triangular patch;
s5: and clustering the triangular patches to generate partition outlines, and acquiring the principal stress field direction of each partition according to the principal stress field of the triangular patches, so as to determine the filling direction of each partition and generate a printing path.
In one embodiment, in the step S1, the STL model is a model data format derived by modeling with CAD software. The layer height is determined according to actual printing requirements, and is generally 0.2mm or 0.4mm. The stress tensor of the unit node calculated by the finite element is obtained by adopting corresponding software such as CAE software according to the actual working condition, carrying out finite element analysis to obtain a post-processing file, and then analyzing the post-processing file. Wherein the post-processing file includes information of the stress tensor of the unit node calculated by the finite element.
In one embodiment, in step S2, slicing the 3D model uses a uniform slice, as shown in fig. 2.
In one embodiment, in the step S3, the triangulating the 2D tangential plane adopts a planar triangulating method, as shown in fig. 3.
In one embodiment, step S4 includes: the method comprises the steps of firstly obtaining the stress tensor of the triangular nodes in the triangular patches, and then combining the stress tensors of the triangular nodes to obtain the combined stress tensor of the triangular patches, so that the combined principal stress field of the triangular patches is calculated through the combined stress tensor of the triangular patches.
Specifically, in an embodiment, the step S4 of obtaining the stress tensor of the triangle node in the triangular patch includes: mapping the space position of the triangular node in the triangular patch into a corresponding three-dimensional finite element, and determining a tetrahedron to which the triangular node in the triangular patch belongs in the three-dimensional finite element, so as to obtain the stress tensor interpolation of the finite element node in the three-dimensional finite element according to the tetrahedron, thereby calculating the stress tensor of the triangular node in the triangular patch.
Specifically, as shown in fig. 4 (a), it is assumed that the target point P in the triangular patch is surrounded by tetrahedrons ABCD, i.e., the tetrahedron to which the target point P belongs includes tetrahedrons ABCD, wherein a, B, C, D are nodes of finite elements, and the volume V formed by the point P and four faces of the tetrahedrons ABCD is first found PABC ，V PABD ，V PBCD ，V PACD Volume V of tetrahedral ABCD ABCD . It is then determined by equation 1.1 whether the target point P is surrounded by tetrahedrons ABCD. Wherein, formula 1.1 is as follows:
V PABC +V PABD +V PBCD +V PACD ＝V ABCD (1.1)
if equation 1.1 holds, it is stated that the target point P is surrounded by tetrahedrons ABCD.
In one embodiment, a nearest field search algorithm (Approximate Nearest Neighbor, ANN) is used to find tetrahedrons around the target point in the triangular patch in the three-dimensional finite element, and then the tetrahedrons surrounding the target point are found by traversing the tetrahedrons around the target point, so that the program running time can be effectively reduced, and the efficiency can be improved.
In one embodiment, after obtaining the target point and the tetrahedron surrounding the target point, the volume coordinates are used as coefficients for stress tensor interpolation. The volume coordinate is formed by the ratio of the volume formed by the target point and four faces of the tetrahedron surrounding the target point to the volume formed by the tetrahedron surrounding the target point. Wherein the volume coordinate of the target point is P (lambda A ，λ B ，λ C ，λ D ) Wherein the coefficient of the stress tensor interpolation of the target point P can be obtained according to equations 1.2 and 1.3. Wherein x is A ，y A ，z A The three-dimensional coordinates of the X, Y and Z axes of the point A are respectively given, and the labels of other points are the three-dimensional coordinates of the X, Y and Z axes of the corresponding points.
λ A ＝V PBCD /V ABCD
λ B ＝V PACD /V ABCD
λ C ＝V PABD /V ABCD
λ D ＝VP ABC /V ABCD (1.3)
The stress tensor sigma of the target point P in the tetrahedron can be obtained according to the coefficient of the stress tensor interpolation P ＝σ A λ A +σ B λ B +σ C λ C +σ D λ D Wherein σ is A 、σ B 、σ C 、σ D The stress tensors of the unit nodes A, B, C, D calculated for the finite elements, respectively. Specifically, the stress tensor of the unit node A, B, C, D of the finite element computation isAnd adopting corresponding software such as CAE software according to actual working conditions, performing finite element analysis to obtain a post-processing file, and then analyzing the post-processing file to obtain the final product. Thus, the stress tensors of the triangular nodes on all the tangent planes can be obtained by traversing the triangular nodes on the whole tangent plane.
In an embodiment, a certain target point in a triangle node may be located on four faces of a tetrahedron or on its sides, i.e. this target point in a triangle node is shared by a plurality of tetrahedrons. At this time, the stress tensors of the target points can be calculated according to the stress tensors of the tetrahedrons of the plurality of shared target points, and then the stress tensors of the triangular nodes of the triangular patches can be calculated in a mean value manner, that is, the calculated stress tensors of the plurality of target points are added up and divided by the number of tetrahedrons surrounding the target points, so as to obtain the stress tensors of the triangular nodes of the triangular patches.
Since the triangle node P is surrounded by a plurality of triangles, as shown in FIG. 4 (b), we need to equally distribute the stress tensor of the triangle node to the nodes of a single triangular patch, i.e., σ E(p) ＝σ F(p) ＝σ G(p) ＝σ H(p) ＝σ I(p) ＝σ J(p) ＝σ p /n p Wherein n is p The number of triangular patches surrounding the target point p is expressed, so that the resultant stress tensor of each triangular patch can be obtained by summing the stress tensors of each triangular patch node. As shown in fig. 4 (c), a, b, c represent three vertices of a single triangular patch surrounding the target point P, the resultant stress tensor σ of the triangular patch G G ＝σ G(a) +σ G(b) +σ G(c) . Finally, the direction and the magnitude of the resultant principal stress field of each triangular patch can be obtained by calculating the eigenvalue and the eigenvector of the resultant stress tensor matrix of the triangular patch, as shown in fig. 5. Specifically, the stress tensor of the triangular patch is effectively a square matrix of 3*3, and the eigenvalues and eigenvectors are determined by applying a square matrix of 3*3. Since this is a square matrix of 3*3, there will be three eigenvalues and three eigenvectors, the three eigenvalues not only have numerical magnitude but also have special physical significance, and the eigenvalue with the largest absolute value is called the largest principalStress. The maximum principal stress and the corresponding characteristic vector are taken together to form the resultant principal stress field. This resultant primary stress field characterizes the direction and magnitude of the maximum primary stress field.
In one embodiment, in the step S5, the clustering principle has two points, one of which must ensure that the triangular patches clustered together are adjacent to each other, and the other must satisfy that the angle difference between the principal stress field direction of the triangular patches clustered together and the reference direction of the subarea is within a certain range, i.e., |y i ·τ(e i ) I > alpha, wherein y i Representing the reference direction in region clustering, τ (e i ) Indicating the direction of the resultant principal stress field for each triangular patch. In an embodiment, the cosine value of the angle difference between the angle of the combined principal stress field direction of each triangular patch of the cluster and the reference direction must be larger than α, where α may take cos10 °.
In one embodiment, clustering triangular patches to generate a partition contour in step S5 includes: and determining the number of the clustered partitions, clustering the triangular patches, and generating partition outlines according to the information of the triangular patches in the partitions.
The number of the partitions may be a preset fixed value, or may be a value that needs to be selected according to actual situations. In one embodiment, in order to consider the overall effect of clustering, i.e., find the correct number of partitions and the appropriate area of partitions, the initial value of the number of partitions is typically set to a large value.
In one embodiment, step S5 includes the steps of:
s51, obtaining the partition iteration reference direction x i ；
Wherein, the partition iterates reference direction x i The initial partition number N is usually set to a large value in order to take account of the overall effect of clustering, i.e. to find the correct partition number and the appropriate partition area, =i×2pi/N (i=1, N). Where j=1, … … N.
S52, according to the principal stress field direction v of the triangular surface patch j And a partition iteration reference directionx i Putting triangular patches into corresponding subareas according to the principle of similar directions;
s53, calculating the reference direction y of each subarea according to the combined principal stress field direction of the triangular patches in each subarea i ；
Specifically, the reference direction of each partition
S54, judging the reference direction y of each partition i Iterative reference direction x to the corresponding partition i Whether the maximum value of the absolute value of the difference value of (a) is smaller than a preset value;
wherein, judging whether the maximum value of the absolute value of the difference value between the reference direction of each partition and the iterative reference direction of the corresponding partition is smaller than a preset value, namely judgingWhether or not this is true, ε is a positive number pre-stored by the system or user, and may be 1e, for example -8 。
If not, the step proceeds to step S55: according to the reference direction y of each partition i To update the corresponding partition iteration reference direction x i ；
Returning to step S52, according to the principal stress field direction v of the triangular patch j And partition iteration reference direction x i Putting triangular patches into corresponding subareas according to the principle of similar directions;
if the value is smaller than the preset value, the step S56 is entered: judging whether the number of triangular patches in the partition is larger than a threshold value or not;
the threshold value nt may be selected according to practical situations.
If not, the process proceeds to step S57: filtering out the subareas with the triangular patches less than the threshold value, and updating the subarea number N;
at this time, after filtering out the partitions, the triangular patches originally belonging to the filtered partitions may be placed again in the remaining corresponding partitions according to the principle of proximity of the main stress field direction, and the partition number N is updated.
Returning to the step S51, obtaining a partition iteration reference direction;
if the threshold value is greater, the process proceeds to step S58: according to the clustering principle, putting triangular patches into corresponding subareas to obtain the combined principal stress field direction information of all the triangular patches in each subareaAnd based on the information of the combined principal stress field direction of all triangular patches in each zone +.>Updating the reference direction y of the corresponding partition i ；
In particular, if the formulaIf so, then it is indicated that the primary cluster reference direction has been generated.
Wherein the method comprises the steps ofIndicating the principal stress field direction information of the triangular patches contained in each partition at this time, and the reference direction y of the partition i Is according to->Is updated and the reference direction y of the partition at that time i As the filling direction of each partition.
S59, according to the triangular patch information in the corresponding subareaGenerating a partition outline, and determining a printing path according to the filling direction of each partition;
wherein triangular patch informationComprises a triangleThe adjacent relation information of the surface patch points and the edges formed between the points is output after plane triangularization of the plane and is used for generating the plane partition outline.
In one embodiment, when the number of the triangular patches in the partition is not changed any more but the triangular patches are still not completely classified, the rest of the triangular patches are only required to be placed in the partition closest to and adjacent to the clustering direction.
In one embodiment, after dividing a planar triangular patch into different regions, the outer contour of the partition needs to be constructed based on the information of the triangular patches in the partition. From observation, the outer contour of each partition is formed by the non-common edges of the triangular patches inside the partition. As shown in fig. 7, the edges of all triangular patches inside the partition can be extracted first. And then removing the repeated edges, and sequentially connecting the edges according to the adjacent sequence of the line segment points to form the outer contour of the subarea. And finally traversing all the partitions to obtain the outer contour of each partition, wherein all the outer contours need to ensure the outer inverse and the inner inverse and can be used for subsequent filling, as shown in fig. 8.
In one embodiment, the print path of each partition is parallel to the fill direction of each partition. After the print path is obtained in step S5, the inside of each partition can be filled according to the print path, and the anisotropy of the printed piece is reduced by adopting a staggered filling mode between layers, so that the practical performance of the process is improved. As shown in fig. 9.
The printing path planning method driven by the main stress field can obviously enhance the strength of the FFF process printing piece and improve the practicality of the whole process.
In one embodiment, a computer device is provided, which may be a terminal, such as a printer. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program, when executed by a processor, implements a print path generation method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, can also be keys, a track ball or a touch pad arranged on the shell of the computer equipment, and can also be an external keyboard, a touch pad or a mouse and the like.
In an embodiment, a computer device is provided, comprising a memory and a processor, the memory having stored therein a computer program, the processor performing the steps of the above-described method embodiments when the computer program is executed.
In one embodiment, a computer-readable storage medium is provided, storing a computer program which, when executed by a processor, implements the steps of the method embodiments described above.
In one embodiment, a computer program product or computer program is provided that includes computer instructions stored in a computer readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps in the above-described method embodiments.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims (8)

1. A print path generation method, characterized by comprising the steps of:
s1, obtaining a stress tensor of a unit node calculated by an STL model, a layer height and a finite element;
s2, slicing the 3D model according to the STL model and the layer thickness to obtain a 2D tangential plane;
s3, performing triangular division on the 2D tangential plane so as to divide the 2D tangential plane into a plurality of triangular patches;
s4, acquiring the combined stress tensor of the triangular patch after acquiring the stress tensor of the triangular patch node in the 2D tangential plane according to the stress tensor of the unit node calculated by the finite element so as to acquire the magnitude of the combined main stress field and the direction of the combined main stress field of the combined stress tensor, thereby acquiring the combined main stress field of the triangular patch;
s5, clustering the triangular patches to generate partition outlines, and acquiring the main stress field closing direction of each partition according to the main stress field closing of the triangular patches, so as to determine the filling direction of each partition and generate a printing path;
wherein, step S4 includes:
acquiring a stress tensor of a triangular node in the triangular patch;
the stress tensors of the triangular nodes are combined to obtain the combined stress tensors of the triangular patches;
and calculating the principal stress field of the triangular patch according to the principal stress tensor of the triangular patch.
2. The print path generation method of claim 1, wherein the obtaining the stress tensor of the triangle node in the triangle patch comprises:
mapping the spatial position of the triangular node in the triangular patch to a corresponding three-dimensional finite element;
determining tetrahedrons of triangular nodes in the triangular patches in the three-dimensional finite element;
and according to the tetrahedron, obtaining the stress tensor interpolation of the finite element nodes in the three-dimensional finite element, and calculating the stress tensor of the triangular nodes in the triangular patch.
3. The print path generation method according to claim 1, wherein the step of determining, in a three-dimensional finite element, a tetrahedron to which a triangle node in the triangle patch belongs includes:
searching tetrahedrons around the target points in the triangular patches according to a nearest field searching algorithm;
traversing tetrahedrons around the target point to obtain tetrahedrons surrounding the target point.
4. The print path generation method according to claim 3, wherein the step of obtaining a stress tensor interpolation of finite element nodes in the three-dimensional finite element based on the belonging tetrahedron, and calculating a stress tensor of triangle nodes in a triangular patch includes:
taking a volume coordinate as a coefficient of the stress tensor interpolation, wherein the volume coordinate comprises a ratio of a volume formed by the target point and four faces of tetrahedron surrounding the target point to a volume of tetrahedron surrounding the target point respectively;
and acquiring the stress tensor of the target point according to the coefficient and the corresponding finite element node.
5. The print path generation method according to claim 1, wherein the step S5 includes:
s51, obtaining a partition iteration reference direction;
s52, placing the triangular patches into corresponding subareas according to the principle that the directions are similar and the main stress field combining direction of the triangular patches and the subarea iteration reference direction are adopted;
s53, calculating the reference direction of each subarea according to the combined principal stress field direction of the triangular patches in each subarea;
s54, judging whether the maximum value of the absolute value of the difference value between the reference direction of each partition and the iterative reference direction of the corresponding partition is smaller than a preset value;
if not, the step proceeds to step S55: updating the corresponding partition iteration reference direction according to the reference direction of each partition;
returning to the step S52, according to the main stress field closing direction of the triangular patches and the partition iteration reference direction, putting the triangular patches into corresponding partitions according to the principle that the directions are similar;
if the value is smaller than the preset value, the step S56 is entered: judging whether the number of triangular patches in the partition is larger than a threshold value or not;
if not, the process proceeds to step S57: filtering out cluster partitions with the triangular patches less than a threshold value, and updating the number of the partitions;
returning to the step S51, obtaining a partition iteration reference direction;
if the threshold value is greater, the process proceeds to step S58: according to a clustering principle, putting triangular patches into corresponding subareas so as to obtain the combined principal stress field direction information of all the triangular patches in each subarea, and updating the reference direction of the corresponding subarea according to the combined principal stress field direction information of all the triangular patches in each subarea;
s59, generating partition outlines according to triangular patch information in the corresponding clustering partitions, and determining printing paths according to the filling direction of each partition.
6. The print path generation method according to claim 5, wherein the clustering principle in step S58 includes: the triangular patches clustered together are adjacent to each other, and the angular difference between the principal stress field direction of the triangular patches clustered together and the reference direction of the partition is within a preset range.
7. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 6 when the computer program is executed.
8. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 6.
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