A modeling method for complex porous structures with controllable boundaries for additive manufacturing

Abstract

The present invention discloses a modeling method for a complex porous structure with controllable boundaries for additive manufacturing, comprising selecting and adopting an implicit surface method to express the porous structure, introducing a number of functions with similar functions, coupling multiple functions, and obtaining a composite function according to the characteristics of different functions, adjusting the composite function parameters according to the superposition state of a two-dimensional transition surface, and obtaining an optimization function by weighting a decision function, thereby solving the problems of a structural blending state occurring in a composite of multiple structures, the problem of using a recursive algorithm for three or more structures, and the problem that there are many control points for dividing the area of ​​the porous structure and the shape of the area boundary is difficult to change according to demand. The porous structure can be filled according to the area range predetermined by the user, so that it is no longer limited to a polygonal area, and a variety of microporous structures can be integrated and formed according to regulations, with strong universality and improved modeling efficiency. Finally, the model is printed by additive manufacturing technology, thereby improving the forming speed and forming quality.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a modeling method for a complex porous structure with controllable boundaries for additive manufacturing. Background Art

[0002] Additive manufacturing, also known as 3D printing, is a "bottom-up" incremental manufacturing technology that has the advantages of low cost and high efficiency in complex surface forming and structural manufacturing, especially in the manufacture of complex precision parts in the fields of aerospace, medical and other fields. At present, the development and application of porous structures are becoming increasingly significant due to their complex internal structures and special characterization morphology. The use of additive manufacturing technology to prepare porous structures and achieve high-quality and accurate physical model printing in a relatively short time is now a hot topic.

[0003] There are many ways to model porous structures, including CAD modeling design, implicit function construction, topology optimization, etc. The CAD modeling method combines single cells or porous units, and uses modeling design software and solid models to perform Boolean operations to construct simple and regular porous structures; topology optimization uses finite element software to perform load analysis on solid models, fills its porous units according to the results, and realizes uneven distribution of materials; the implicit surface construction method converts the existing multiple porous units into mathematical function expressions, and uses function combinations to construct porous structures with multiple composite configurations. At present, the existing implicit construction method has the following limitations: using the S function, two porous structures can be simply linearly compounded, and three or more structures will have superposition of different structures. More structural combinations can only be achieved through recursive algorithms at the expense of computing time; using distance field theory, multiple porous structure combinations can be achieved through functions, but a corresponding number of control points need to be provided, and the area divided by the control points is a polygonal area. In this method, the structural partition cannot change shape as required, and the constraints are relatively large.

[0004] Therefore, it is necessary to provide a complex porous structure modeling method with controllable boundaries for additive manufacturing technology without increasing the complexity. Summary of the invention

[0005] The present invention provides a modeling method for a complex porous structure with controllable boundaries for additive manufacturing.

[0006] To achieve the above object, the present invention provides the following technical solution: a modeling method for complex porous structures with controllable boundaries for additive manufacturing, comprising the following steps:

[0007] S1. Select and use implicit surface method to express porous structure;

[0008] S2. Introduce several functions with similar functions, couple multiple functions, and combine them according to the characteristics of different functions to obtain a composite function;

[0009] S3. Adjust the composite function parameters according to the superposition state of the two-dimensional transition surface, and use the decision function to weight the optimization function:

[0010] S4. Change the decision function and replace it with a known one-dimensional graphical expression, observe the changes in the porous filling area and the boundary, and verify it.

[0011] Preferably, in step S1, the limitations of existing modeling methods are analyzed, the type of porous structure is selected, and the implicit surface method is used to express it to obtain the reasons for the limitations.

[0012] Preferably, in step S2, a plurality of functions with similar functions are selected according to the porous structure combination principle and the functional characteristics of the weight factor.

[0013] Preferably, the selecting of multiple functions having similar functions specifically includes:

[0014] a. Select similar functions based on the characteristics of the S-type growth function;

[0015] b. Select the combination model based on the feature whose coefficient probability and sum is 1.

[0016] Preferably, in step S2, any number of two or more porous structures can be combined, and the expression is:

[0017] Preferably, in step S2, the multi-function coupling method includes function nesting, product, and addition, and its expression is:

[0018]

[0019]

[0020] Preferably, in step S3, the specific process of optimizing the function includes:

[0021] a. Obtain different two-dimensional partitioning surfaces according to multiple coupling functions;

[0022] b. Select functions that meet the preset conditions;

[0023] c. Observe boundary features and introduce decision function weighting for improvement;

[0024] d. Draw the improved partition surface and close it into a body through the surface;

[0025] e. Fill different areas of the porous structure.

[0026] Preferably, when a linear boundary appears in a combination of multiple two-dimensional surface areas, a decision function is used for weighting so that the straight line segment is mapped into a shape required by the user.

[0027] Preferably, in step S4, verifying the model specifically includes:

[0028] a. Establish a variety of different porous structure combination models to observe the intrinsic characteristics of different structures;

[0029] b. Predefine a shape function, introduce it into the combination model through weighting, adjust the parameters and observe the shape change of the combination area;

[0030] c. Predefine a porous structure, fill the shape area, adjust the parameters and observe the changes in the structure of the area;

[0031] d. Repeat steps b and c multiple times to complete model verification.

[0032] Preferably, the verified model is exported to an STL file format, and the solid result is printed using a 3D printing device.

[0033] Compared with the prior art, the present invention has the following beneficial effects: the present invention firstly adopts implicit function expression method to represent the porous structure, and realizes the composite of the porous structure by function combination, thereby solving the problem of structural mixing state in the composite of multiple structures, the problem of using recursive algorithm for three or more structures, the problem of too many control points in the area division of the porous structure and the problem that the shape of the area boundary is difficult to change according to the demand;

[0034] Secondly, by introducing several functions with similar functions, multiple functions are coupled, and composite functions are obtained according to the characteristics of different functions. Through optimization, the porous structure is filled in the area range predetermined by the user, so that it is no longer limited to the polygonal area, and various microporous structures can be integrated into one according to regulations. It has strong universality and improved modeling efficiency. Finally, the model is printed by additive manufacturing technology, which improves the molding speed and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0036] In the attached picture:

[0037] Figure 1 is a flow chart of the modeling method of the present invention;

[0038] Figure 2 It is a schematic diagram of the modeling area of ​​the present invention;

[0039] Figure 3is a boundary curve diagram of the present invention;

[0040] Figure 4 It is a partition diagram of the porous structure of the present invention;

[0041] Figure 5 is a weighted porous structure partition diagram of the present invention;

[0042] Figure 6 This is a diagram of a coupled porous structure model of the present invention;

[0043] Figure 7 It is a diagram of the modeling verification results of the present invention. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0045] Example: Figure 1-6 As shown, a modeling method for a complex porous structure with controllable boundaries for additive manufacturing can realize multi-region division. The divided regions and boundaries can meet the planning requirements of customers and can fill the required porous structure, including the following steps:

[0046] S1. Select and use the implicit surface method to express the porous structure, wherein the limitations of the existing modeling methods are analyzed, the type of porous structure is selected, and the implicit surface method is used to express it, and the reasons for the limitations are obtained;

[0047] S2. According to the principle of porous structure combination and the functional characteristics of weight factors, several functions with similar functions are introduced. The functions with similar functions are selected as follows:

[0048] a. Select similar functions based on the characteristics of the S-type growth function;

[0049] b. Select the combination model based on the feature whose coefficient probability and sum is 1;

[0050] It is possible to combine any number of 2 or more porous structures, and the expression is:

[0051]

[0052] Couple multiple functions and combine them according to their characteristics to get composite functions. Figure 3 As shown;

[0053] Among them, the multi-function coupling methods include function nesting, product, and addition, and the expression is:

[0054]

[0055]

[0056] S3, adjusting the composite function parameters according to the superposition state of the two-dimensional transition surface, and obtaining the optimization function by weighting the decision function;

[0057] The specific process of optimizing the function includes:

[0058] a. Obtain different two-dimensional partitioning surfaces based on multiple coupling functions, refer to Figure 4 As shown;

[0059] b. Select a function that meets the preset conditions. In this embodiment, a function with a low degree of surface integration and a good degree of compositeness is selected;

[0060] c. Observe boundary features and introduce decision function weighting for improvement. Figure 5 As shown, when multiple two-dimensional surface areas are combined to form a linear boundary, a decision function is used to weight the straight line segment so that it is mapped into the shape required by the user;

[0061] d. Draw the improved partition surface and close it into a body through the surface;

[0062] e. Reference Figure 6 , filling different areas of the porous structure;

[0063] S4. Change the decision function and replace it with a known one-dimensional graphical expression, observe the changes in the porous filling area and the boundary, and verify it, including:

[0064] a. Establish a variety of different porous structure combination models to observe the intrinsic characteristics of different structures;

[0065] b. Predefine a shape function, introduce it into the combination model through weighting, adjust the parameters and observe the shape change of the combination area;

[0066] c. Predefine a porous structure, fill the shape area, adjust the parameters and observe the changes in the structure of the area;

[0067] d. Repeat steps b and c multiple times to complete model verification.

[0068] The verified model is exported to STL file format and the solid result is printed using 3D printing equipment.

[0069] In a specific embodiment, the above method is used to arbitrarily combine the D, G, P, G', and I-WP structures, and introduce boundary functions of different shapes to change the porous filling area, specifically:

[0070] Selecting D, G, P, G', and I-WP surface implicit expressions, the function expression corresponding to the porous structure is:

[0071] (1) Φ I-WP (X (j) )=cos(x)cos(y)+cos(y)cos(z)+cos(z)cos(x)-cos(x)cos(y)cos(z)+C;

[0072] (2) Φ D (X (j) )=cos(x)cos(y)cos(z)-sin(x)sin(y)sin(z)+C;

[0073] (3) Φ P (X (j) ) = cos(x) + cos(y) + cos(z) + C;

[0074] (4) Φ G (X (j) )=sin(x)cos(y)+sin(y)cos(z)+sin(z)cos(x)+C;

[0075] (5) Φ D′ (X (j) )=(cos(x)cos(y)cos(z)-sin(x)sin(y)sin(z)) 2 +C;

[0076] Follow the above steps to build a model and verify the model. The user enters a circular expression, gives a dot and a radius, and hopes to fill this area with a P porous structure. In the final model, the porous structure area is constructed within the specified area, which means that the verification is successful. Repeatedly change the shape expression and the required filling structure, and the result Figure 7 It can be seen from the figure that all requirements are met and the verification is successful.

[0077] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A modeling method for complex porous structures with controllable boundaries for additive manufacturing, characterized by: The steps include: S1. Select and use implicit surface method to express porous structure; S2. Introduce several functions with similar functions, couple multiple functions, and combine them according to the characteristics of different functions to obtain a composite function; It is possible to combine any number of 2 or more porous structures, and the expression is: ； S3, adjusting the composite function parameters according to the superposition state of the two-dimensional transition surface, and obtaining the optimization function by weighting the decision function; The specific process of optimizing the function includes: a. Obtain different two-dimensional partitioning surfaces according to multiple coupling functions; b. Select functions that meet the preset conditions; c. Observe boundary features and introduce decision function weighting for improvement; d. Draw the improved partition surface and close it into a body through the surface; e. Filling different areas of the porous structure; When multiple two-dimensional surface areas are combined to form a linear boundary, a decision function is used to weight the straight line segment so that it is mapped into the shape required by the user; S4. Change the decision function and replace it with a known one-dimensional graphical expression, observe the changes in the porous filling area and the boundary, and verify it.

2. The modeling method of a complex porous structure with controllable boundaries for additive manufacturing according to claim 1, characterized in that: In step S1, the limitations of existing modeling methods are analyzed, the type of porous structure is selected, and the implicit surface method is used to express it to obtain the reasons for the limitations.

3. The modeling method of a complex porous structure with controllable boundaries for additive manufacturing according to claim 1, characterized in that: In step S2, a plurality of functions with similar functions are selected according to the porous structure combination principle and the functional characteristics of the weight factor.

4. The modeling method of a complex porous structure with controllable boundaries for additive manufacturing according to claim 3, characterized in that: in, Selecting multiple functions with similar functionality specifically includes: a. Select similar functions based on the characteristics of the S-type growth function; b. Select the combination model based on the feature whose coefficient probability and sum is 1.

5. The modeling method of a complex porous structure with controllable boundaries for additive manufacturing according to claim 1, characterized in that: In step S2, the multi-function coupling method includes function nesting, product, and addition, and its expression is: ； 。 6. The modeling method of a complex porous structure with controllable boundaries for additive manufacturing according to claim 1, characterized in that: In step S4, verifying the model specifically includes: a. Establish a variety of different porous structure combination models to observe the intrinsic characteristics of different structures; b. Predefine a shape function, introduce it into the combination model through weighting, adjust the parameters and observe the shape change of the combination area; c. Predefine a porous structure, fill the shape area, adjust the parameters and observe the changes in the structure of the area; d. Repeat steps b and c multiple times to complete model verification.

7. The modeling method of a complex porous structure with controllable boundaries for additive manufacturing according to claim 1, characterized in that: The verified model is exported to STL file format and the solid result is printed using 3D printing equipment.

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