Supporting piece implicit curved surface variable direction point lattice structure design method for additive manufacturing

Abstract

The application relates to a support implicit curved surface variable-direction point lattice structure design method for additive manufacturing, which comprises the following steps: S1, establishing a three-dimensional model of a unit cell of a support implicit curved surface point lattice structure; S2, determining a load transmission direction of the support implicit curved surface point lattice structure according to force balance; S3, constructing a variable-direction point lattice structure data set according to the load transmission direction in a support finite element entity model; and S4, completing the modeling of the support implicit curved surface variable-direction point lattice structure. The application considers the influence of the load direction of the unit cell of the support implicit curved surface point lattice structure on the mechanical performance parameters, makes the principal stress of the unit cell consistent with the direction with strong point lattice structure performance, and improves the bearing performance of the support; the arrangement of a skin between the unit cells of the support solves the problem that changing the direction of the point lattice structure unit cell will damage the original through curved surface of the implicit curved surface, and the modeling of the support implicit curved surface variable-direction point lattice structure is completed.

Description

Technical Field

[0001] This invention belongs to the field of computer-aided design technology in additive manufacturing processes, and specifically relates to a design method for implicit curved surface variable direction lattice structure of support components used in additive manufacturing. Background Technology

[0002] As a novel material structure, lattice structures possess advantages such as lightweight, high strength, and high energy absorption and vibration isolation, and are widely used in aerospace, automotive manufacturing, medical devices, and other fields. However, traditional microtruss lattice structures have non-uniform transitions at the geometric unit connections, with sharp turns or corners, making them prone to stress concentration at these joints under structural stress. In contrast, implicit surfaces are isomorphic surfaces with a clearly defined spatial distribution, expressed as mathematical functions. They have smooth surfaces and are fully interconnected internally, possessing porous and self-supporting characteristics. They do not suffer from stress concentration issues at the connections between adjacent members of microtrusses. Therefore, implicit surface lattice structures have greater application potential across various industries.

[0003] Studies have shown that, under the same load, variable-density implicit surface lattice structures exhibit better mechanical performance parameters than uniform-density implicit surface lattice structures. However, current optimization of implicit surface lattice structures primarily focuses on the density distribution of the internal cells, neglecting the influence of load direction on their mechanical performance parameters. In fact, the anisotropic characteristics of implicit surface cells have been discovered by engineers, and the location where lattice structures first fail in practical applications is often the load-bearing direction where their mechanical performance parameters are weakest. Therefore, the design and optimization of implicit surface lattice structures must consider the impact of load direction on their service performance. Furthermore, the cell of an implicit surface lattice structure is a complete, continuous surface; changing the orientation of cells in different regions of the structure based on the load transfer direction will disrupt the original continuous surface. Thus, modeling variable-orientation implicit surface lattice structures is a major challenge in the design process. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a design method for implicit curved surface variable-direction lattice structures of support components for additive manufacturing. During the design process, this invention considers the influence of the load direction of the implicit curved surface lattice structure cell on the mechanical performance parameters of the cell, ensuring that the principal stress direction of each support component cell unit is consistent with the direction of the strongest lattice structure performance, thus improving the load-bearing capacity of the support component structure. Furthermore, the use of skins between support component cells solves the problem that changing the lattice structure cell direction would disrupt the original continuous curved surface of the implicit curved surface of the support component, thus completing the variable-direction cell modeling of the implicit curved surface lattice structure of the support component.

[0005] To achieve the above objectives, the present invention provides a method for designing an implicit curved surface variable orientation lattice structure for additive manufacturing support components, comprising:

[0006] S1: Establish a 3D unit cell model of the implicit curved surface lattice structure of the support for additive manufacturing; since the implicit curved surface lattice structure based on additive manufacturing has rotational symmetry, the load application direction also has a symmetrical effect; establish 3D unit cell models at multiple rotation angles, and use finite element simulation technology to analyze the mechanical properties of the unit cell models under each rotation direction, including deformation and stress, provide anisotropy radar charts, and determine the target rotation angle θ. G ;

[0007] S2: Determine the load transfer direction of the implicit curved surface lattice structure of the support component in the additive manufacturing process based on the force balance.

[0008] S21: Establish a finite element solid model of the implicit curved surface lattice structure of the support component in the additive manufacturing process, perform mesh generation, apply constraints and loads, and number the generated elements. There are a total of n elements.

[0009] S22: Based on the principle of force balance, extract the stress vectors of each element in the finite element solid model of the support component and store them in dataset a. β In the middle, construct a two-dimensional planar structural stress vector model and a three-dimensional solid structural stress vector model of the support component;

[0010] S23: Based on the stress vector model of the two-dimensional planar structure of the support component, the load transfer direction of each element in the two-dimensional solid model of the support component is determined as follows:

[0011] v2 β = (θx, θy);

[0012] Among them, v2 β θx is the load transfer direction of the β-th element; θy is the angle between the stress vector in the transverse direction and the horizontal direction; β is the element number of the solid model, β = 1, 2, 3...n, where n is the total number of solid model elements;

[0013] S24: Based on the stress vector model of the three-dimensional structure of the support component, the load transfer direction of each element in the three-dimensional solid model of the support component is determined as follows:

[0014] v3 β = (θx, θy, θz);

[0015] Among them, v3 β θz represents the load transfer direction of the β-th element; θz is the angle between the vertical stress vector and the horizontal direction.

[0016] S3: Based on step S2, calculate the load transfer directions of all elements in the finite element solid model of the support component, and make the optimal rotation direction θ of the implicit curved surface cell of the support component in step S1 the optimal rotation direction θ. GConsistent with the load transfer direction of the corresponding unit, datasets of improved variable-direction lattice structures under two-dimensional and three-dimensional support structures are constructed respectively.

[0017] S31: For the two-dimensional structure of the support, the optimal rotation direction θ in step S1 is... G The load transfer direction v2 of each element of the two-dimensional solid model of the support member is determined in step S23. β Equal to obtain the rotation angle of the implicit curved surface lattice structure cell of the support, and store it in the improved variable orientation lattice structure dataset G2 under the two-dimensional structure of the support. β middle;

[0018] S32: For the three-dimensional structure of the support, the axis of rotation is the one with the smallest stress vector magnitude in the three coordinate directions, so that the load transfer direction v3 of each element of the three-dimensional solid model of the support is determined in step S24. β Rotation angle θ of the target in step S1 G The obtained rotation axis information is stored in the improved variable orientation lattice structure dataset G3 under the three-dimensional structure of the support component. β middle;

[0019] S4: Perform implicit surface modeling of the support component to complete the modeling of the implicit surface variable-direction lattice structure of the support component; perform Boolean merging between the skin and the improved variable-direction lattice structure dataset obtained in step S3 to achieve the connection and penetration between the unit cells of the implicit surface lattice structure of the support component, thereby obtaining the improved variable-direction implicit surface lattice structure of the support component with skin; the equation expression of the implicit surface lattice structure of the support component is:

[0020]

[0021] Where t is the parameter controlling the cell porosity; L is the cell size parameter; x is the horizontal axis parameter; y is the vertical axis parameter; and z is the vertical axis parameter.

[0022] By controlling the connection and penetration of all unit cells according to the implicit surface equation of the support, a unit cell orientation model of the implicit surface lattice structure of the support is obtained, which is used for additive manufacturing of the support.

[0023] Preferably, the stress vector model for constructing the two-dimensional planar structure of the support member in step S2 is as follows:

[0024]

[0025] Among them, V 2x V represents the direction of the force transmission path vector along the horizontal axis of a two-dimensional coordinate system. 2y σ represents the direction of the force transmission path vector along the vertical axis of the two-dimensional coordinate system. x The stress is in the transverse direction; τ xy τ represents the shear stress along the horizontal and vertical axes;yx For the shear stress along the longitudinal and transverse axes; σ y is the stress along the vertical axis; i and j are unit vectors along the horizontal and vertical axes, respectively.

[0026] Preferably, the three-dimensional stress vector model of the support structure in step S2 is as follows:

[0027]

[0028] Among them, V 3x V represents the direction of the force transmission path vector along the horizontal axis of the three-dimensional coordinate system. 3y V represents the direction of the force transmission path vector along the vertical axis of the three-dimensional coordinate system. 3z τ represents the direction of the force transmission path vector along the vertical axis of the three-dimensional coordinate system. zx For the shear stresses along the vertical and horizontal axes; τ zy For the shear stresses along the vertical and longitudinal axes; τ xz τ represents the shear stress along the horizontal and vertical axes; yz For the shear stress along the longitudinal axis and the vertical axis; σ z is the stress in the vertical direction; k is the unit vector in the vertical direction.

[0029] Preferably, the angle θx between the stress vector along the horizontal axis and the horizontal direction, and the angle θy between the stress vector along the vertical axis and the horizontal direction in step S2 are specifically as follows:

[0030] The angle θx between the stress vector in the transverse direction and the horizontal direction is:

[0031]

[0032] Where θx is the angle between the stress vector in the transverse direction and the horizontal direction;

[0033] The angle θy between the stress vector along the longitudinal axis and the horizontal direction is:

[0034]

[0035] Where θy is the angle between the stress vector along the vertical axis and the horizontal direction.

[0036] Preferably, in step S4, implicit surface modeling of the support member is performed, specifically as follows:

[0037] S41: Substitute the load transfer direction of each unit corresponding to the implicit curved surface cell of the support obtained in step S3 into the implicit curved surface equation of the support, perform unit cell surface modeling of the implicit curved surface lattice structure of the support, and obtain the expression of the implicit curved surface equation of the support.

[0038] S42: Perform Boolean operations on the implicit surface lattice structure unit cell surface of the support member corresponding to each unit obtained in step S41 and the solid model in step S21 to obtain the closed structure of the implicit surface lattice structure unit cell of the support member, forming an independent space. After Boolean subtraction operation between the implicit surface of the support member and its solid structure, the support member Gyroid unit cell is obtained. All closed unit cells are matched with the unit positions of the support member solid model in step S21 to obtain a skinless variable orientation lattice structure.

[0039] S43: Construct a skin structure with a thickness of 3mm and an overall size equal to that of the solid model of the support in step S21, and obtain the skinless variable orientation lattice structure constructed in S42. Adjust the position of the skin and the implicit curved surface lattice structure of the support to align them in space. Perform Boolean merging to achieve the connection between the cell and the skin, making them a whole, ensuring the connection of all cells, and obtaining the final implicit curved surface lattice structure of the variable orientation support with skin.

[0040] Preferably, the implicit function expression of the implicit surface of the support member in step S4 is:

[0041]

[0042] The implicit surface function indicates that the period of the Gyroid surface of the support is the same in the three coordinate axes of the three-dimensional coordinate system and is equal to 5. That is, the size of the Gyroid unit cell of the support is 5mm×5mm×5mm. The equivalent parameter t of the implicit function of the Gyroid surface of the support is 0, that is, the porosity is 50%.

[0043] Preferably, in step S4, when the implicit curved surface of the support member is rotated, the formula for setting the rotation angle θ around the horizontal axis is:

[0044]

[0045] Where x' is the horizontal coordinate parameter after rotation; y' is the vertical coordinate parameter after rotation; z' is the vertical coordinate parameter after rotation; x is the horizontal coordinate parameter before rotation; y is the vertical coordinate parameter before rotation; z is the vertical coordinate parameter before rotation; and θ is the rotation angle.

[0046] Preferably, in step S4, when the implicit curved surface of the support member is rotated, the formula for setting the rotation angle θ around the longitudinal axis is:

[0047]

[0048] Preferably, in step S4, when the implicit curved surface of the support member is rotated, the formula for setting the rotation angle θ in the vertical direction is:

[0049]

[0050] Furthermore, in a preferred embodiment, the plurality of rotation angles are 0 degrees, 15 degrees, 22.5 degrees, 30 degrees and 45 degrees, respectively.

[0051] Compared with the prior art, the present invention has the following beneficial effects: In the process of designing the lattice structure, the method considers the anisotropy of the implicit curved surface lattice structure cell of the support member, that is, the influence of the load direction on the mechanical performance parameters of the cell, so that the principal stress direction of each finite element of the support member is consistent with the direction of the lattice structure with stronger performance, thereby improving the load-bearing performance of the support member structure; Since changing the orientation of the cell in each region of the lattice structure due to the load transfer direction will destroy the original continuous surface of the implicit curved surface of the support member, this problem is solved by arranging skins between cells and using Boolean operations, which provides certain guidance for the modeling of variable orientation lattice structures. Attached Figure Description

[0052] Figure 1 This is a flowchart of the design method for an implicit curved surface variable orientation lattice structure of a support for additive manufacturing according to the present invention.

[0053] Figure 2 Radar diagram showing the anisotropy results of the Gyro id dot matrix structure supporting the present invention;

[0054] Figures 3(a) and (b) are respectively diagrams of the two-dimensional and three-dimensional structure cell orientation strategies of the support component of the present invention;

[0055] Figure 4 This is a schematic diagram showing the load boundary conditions of the two-dimensional three-point bending beam support component of the present invention and the optimal orientation of the Gyroid lattice cell.

[0056] Figure 5 This is a schematic diagram of the load boundary conditions of the three-dimensional structure of the support member of the present invention;

[0057] Figures 6(a)-(e) are schematic diagrams of the orientation of the five Gyroid unit cells of the present invention, which are respectively oriented along the positive z-axis.

[0058] Figure 7 This is a schematic diagram of the modeling process of the support unit cell of the present invention from a single curved surface to the interconnection between unit cells;

[0059] Figure 8 This is a visual schematic diagram of the three-point bending beam dot matrix of the support component of the present invention;

[0060] Figures 9(a)-(f) are schematic diagrams of the layering and overall visualization of the three-dimensional lattice structure model of the support component of the present invention;

[0061] Figures 10(a)-(b) are comparison images of the original Gyroid lattice structure (Gyroid-2U) and the variable-direction Gyroid lattice structure (Gyroid-2G) photopolymerization models of the two-dimensional three-point bending beam supporting component.

[0062] Figures 11(a) and (b) are comparison images of the original three-dimensional Gyroid lattice structure (Gyroid-3U) and the photopolymerization model of the variable-direction Gyroid lattice structure (Gyroid-3G) of the support component;

[0063] Figures 12(a)-(b) show the test curves of mechanical performance parameters of the two-dimensional and three-dimensional homogeneous and variable-direction Gyroid lattice structures of the support component of the present invention. Detailed Implementation

[0064] Exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0065] This invention provides a design method for an implicit curved surface variable-direction lattice structure of a support for additive manufacturing. Two-dimensional structural examples can be used for the analysis and modeling of bending beams, while three-dimensional examples serve as the analysis and modeling of the support entity. Both the bending beam and the support entity are referred to as "support" in this invention. Figure 1 The diagram shows a flowchart of the design method for an implicit curved surface variable orientation lattice structure of a support for additive manufacturing according to the present invention. The method involves establishing a 3D cellular model of the implicit curved surface lattice structure of the support with a defined rotation direction; determining the load transfer direction of the corresponding solid model of the implicit curved surface lattice structure of the support based on force balance; constructing an improved variable orientation lattice structure dataset based on the load transfer direction; performing implicit surface modeling of the support; and obtaining a cellular variable orientation model of the implicit curved surface lattice structure of the support. Specific steps include:

[0066] Step S1: Establish a 3D cell model of the implicit curved surface lattice structure of the support member with a set rotation direction; since the support member has 90-degree rotational symmetry in the

[001] direction for the Gyroid implicit curved surface lattice structure, and the load loading directions of 0-45 degrees and 45-90 degrees also have symmetry effects; establish 3D cell models of the support member with multiple rotation angles respectively, and use finite element simulation technology to analyze the mechanical performance parameters of the support member cell model under each rotation direction, including deformation and stress, and give an anisotropy result radar chart to determine the target rotation angle θ. G ;like Figure 2 The image shown is a radar diagram of the anisotropy results of the Gyroid lattice structure of the support component of the present invention. It can be seen that the mechanical performance parameters of the lattice structure of the support component cell are optimal when rotated by 45 degrees.

[0067] Step S2: Determine the load transfer direction of the implicit curved surface lattice structure of the support component in the additive manufacturing process based on the force balance.

[0068] Step S21: Establish the finite element model of the solid model corresponding to the implicit curved surface lattice structure of the support component, mesh the solid model of the support component, apply constraints and loads, and number the meshed elements. There are a total of n elements.

[0069] Step S22: Based on the principle of force balance, extract the stress vectors of each element in the solid model of the support component and store them in dataset a. β In the middle section, a two-dimensional planar structural stress vector model and a three-dimensional solid structural stress vector model of the support component are constructed, as shown below:

[0070] The formula for the stress vector model of the two-dimensional planar structure of the support member is:

[0071]

[0072] Among them, V 2x V represents the direction of the force transmission path vector along the horizontal axis of a two-dimensional coordinate system. 2y σ represents the direction of the force transmission path vector along the vertical axis of the two-dimensional coordinate system. x Stress is in the transverse direction; τ xy τ represents the shear stress along the horizontal and vertical axes. yx For the shear stress along the longitudinal and transverse axes; σ y is the stress along the vertical axis; i and j are unit vectors along the horizontal and vertical axes, respectively.

[0073] The stress vector model of the three-dimensional structure of the support is as follows:

[0074]

[0075] Among them, V 3x V represents the direction of the force transmission path vector along the horizontal axis of the three-dimensional coordinate system. 3y V represents the direction of the force transmission path vector along the vertical axis of the three-dimensional coordinate system. 3z τ represents the direction of the force transmission path vector along the vertical axis of the three-dimensional coordinate system. zx For the shear stresses along the vertical and horizontal axes; τ zy For the shear stresses along the vertical and longitudinal axes; τ xz τ represents the shear stress along the horizontal and vertical axes; yz For the shear stress along the longitudinal axis and the vertical axis; σ z is the stress in the vertical direction; k is the unit vector in the vertical direction.

[0076] Step S23: Determine the load transfer direction of each element in the two-dimensional solid model of the support component based on the stress vector model of the two-dimensional planar structure of the support component:

[0077] v2 β = (θx, θy);

[0078] Among them, v2 β θx represents the load transfer direction of the β-th element; θy represents the angle between the stress vector along the horizontal axis and the horizontal direction; β represents the element number of the solid model, β = 1, 2, 3...n, where n is the total number of solid model elements.

[0079] The angles θx and θy between the stress vector along the horizontal axis and the horizontal direction, respectively, are as follows:

[0080] The angle θx between the stress vector along the transverse axis and the horizontal direction is:

[0081]

[0082] Where θx is the angle between the stress vector along the horizontal axis and the horizontal direction.

[0083] The angle θy between the stress vector along the vertical axis and the horizontal direction is:

[0084]

[0085] Where θy is the angle between the stress vector along the vertical axis and the horizontal direction.

[0086] Step S24: Determine the load transfer direction of each element in the three-dimensional solid model of the support component based on the stress vector model of the three-dimensional structure of the support component:

[0087] v3 β = (θx, θy, θz);

[0088] Among them, v3 β θz represents the load transfer direction of the β-th element; θz is the angle between the vertical stress vector and the horizontal direction.

[0089] The load transfer direction of each element in the 3D solid model of the support needs to be determined based on the magnitudes of the three vector moduli identified in step S22. The axis with the smallest modulus is chosen as the rotation axis, which is equivalent to rotating in the plane corresponding to the other two axes. Since the anisotropy result of the support's Gyroid is that the mechanical performance parameters are best in the 45° direction, rotating 45° around the rotation axis in the plane of the other two axes will align the direction with the best mechanical performance parameters with the two axes with the largest stress vector moduli.

[0090] Step S3: Based on the load transfer directions of all elements in the finite element solid model of the support component calculated in Step S2, determine the optimal rotation direction θ of the implicit curved surface cell of the support component in Step S1. GConsistent with the load transfer direction of the corresponding unit, improved variable-direction lattice structure datasets for the two-dimensional and three-dimensional support structures are constructed respectively.

[0091] Figure 3(a) shows the cell orientation strategy of the two-dimensional structure of the support component of the present invention. The implicit curved surface cell orientation is guided by the stress vectors in the x and y directions of the two-dimensional planar unit. For example, as shown in the figure, if the stress vector magnitude in the x direction is the largest, it can be seen that the angle between it and the x-axis is 65 degrees. In order to align the best direction of the mechanical performance parameters of the support component cell with the principal stress vector in the x direction, the cell is rotated counterclockwise by 20 degrees in the xy plane.

[0092] Figure 3(b) shows the cell orientation strategy of the three-dimensional structure of the support component according to the present invention. The implicit curved surface cell orientation is guided by the stress vectors in the x, y, and z directions of the three-dimensional structural unit of the support component. For example, as shown in the figure, if the stress vector magnitude in the x direction is the smallest, in order to match the best direction of the mechanical performance parameters of the support component cell with the principal and secondary stress vectors, the cell is rotated 45 degrees around the x-axis in the yz plane to ensure that the best direction of the mechanical performance parameters of the cell is aligned with the y and z axes.

[0093] Step S31: For the two-dimensional structure of the support member, the optimal rotation direction θ from step S1 is... G The load transfer direction v2 of each element of the two-dimensional solid model of the support member is determined in step S23. β Equal to obtain the rotation angle of the implicit curved surface lattice structure cell of the support, and store it in the improved variable orientation lattice structure dataset G2 under the two-dimensional structure of the support. β middle.

[0094] like Figure 4 The diagram illustrates the load boundary conditions of the two-dimensional three-point bending beam support of this invention and the optimal orientation of the Gyroid lattice cells. The two-dimensional three-point bending beam has dimensions of 100mm × 30mm, which is 20 cell lengths in the x-direction and 6 cell lengths in the y-direction. First, a vertical downward load of 100N is applied to the bottom two ends of the two-dimensional planar structure of the support and to the middle of the top end. The stress components are extracted from the stress analysis results under this condition to calculate the element stress vector. Second, the implicit curved surface cell rotation angle is guided by the element stress vector, and the optimal direction of the implicit curved surface cell mechanical property parameters is appropriately aligned with the principal stress. Based on this, the cell orientation information at the location of the element shown in the figure is obtained. Since the load and boundary conditions are symmetrical along the centerline, this patent shows the cell orientation information at the location of the element on the left side of the symmetry axis.

[0095] Step S32: For the three-dimensional structure of the support, take the axis of rotation with the smallest stress vector magnitude in the three coordinate directions, so that the load transfer direction v3 of each element of the three-dimensional solid model of the support is determined in step S24. β Rotation angle θ with target S1G The obtained rotation axis information is stored in the improved variable orientation lattice structure dataset G3 under the three-dimensional structure of the support component. β middle;

[0096] like Figure 5 The diagram shows the load boundary conditions of the three-dimensional support structure of the present invention and the optimal orientation of the Gyroid lattice cell. The three-dimensional solid structure has dimensions of 100mm × 50mm × 25mm. It is subjected to a 5000N vertically downward force along the z-direction within a 10mm × 10mm area at the top center, and the four corners at the bottom are fixed within a 10mm × 10mm area. For clear visualization, [the diagram is shown below]. Figures 6(a)-6(e) Five schematic diagrams showing the orientation of Gyroid cells layer by layer along the positive z-axis present the cell orientation information, providing basic data for subsequent support modeling.

[0097] Step S4: Perform implicit surface modeling of the support component to complete the modeling of the implicit surface variable direction lattice structure of the support component;

[0098] Perform implicit surface modeling of the support components, such as Figure 7 The diagram shows the modeling process of the support cell of the present invention from a single curved surface to the interconnection between cells. The specific steps are as follows:

[0099] Step S41: Substitute the load transfer direction of each unit corresponding to the implicit curved surface cell of the support obtained in step S3 into the implicit curved surface equation of the support, perform unit cell surface modeling of the implicit curved surface lattice structure of the support, and obtain the expression of the implicit curved surface equation of the support.

[0100] Step S42: Perform Boolean operations on the implicit surface lattice structure unit cell surface of the support member corresponding to each unit obtained in Step S41 and the solid model in Step S21 to obtain the closed structure of the implicit surface lattice structure unit cell of the support member, forming an independent space. After Boolean subtraction between the implicit surface of the support member and its solid structure, the support member Gyroid unit cell is obtained. Correspond all closed unit cells to the unit positions of the support member solid model in Step S21 to obtain a skinless variable orientation lattice structure.

[0101] Step S43: Construct a skin structure with a thickness of 3mm and an overall size equal to that of the solid model of the support in step S21, and obtain the skinless variable orientation lattice structure constructed in S42. Adjust the position of the skin and the implicit curved surface lattice structure of the support to align them in space. Perform Boolean merging to achieve the connection between the cell and the skin, making them a whole and ensuring the connection of all cells, to obtain the final implicit curved surface lattice structure of the variable orientation support with skin.

[0102] Boolean merge the skin and the improved variable orientation lattice structure dataset obtained in step S3 to achieve the connection between the unit cells of the implicit curved surface lattice structure of the support, and obtain the improved variable orientation support implicit curved surface lattice structure with skin.

[0103]

[0104] Where t is the parameter controlling the cell porosity; L is the cell size parameter; x is the horizontal axis parameter; y is the vertical axis parameter; and z is the vertical coordinate parameter.

[0105] The implicit function expression for the implicit surface of the support member is:

[0106]

[0107] The implicit surface function is represented as follows: the period of the support Gyroid surface is the same in the three coordinate axes of the three-dimensional coordinate system and is equal to 5. That is, the size of the support Gyroid unit cell is 5mm×5mm×5mm. The equivalent parameter t of the implicit function of the support Gyroid surface is 0, that is, the porosity is 50%.

[0108] When the implicit curved surface of the support component is rotated, the formula for setting the rotation angle θ on the horizontal axis is:

[0109]

[0110] Where x' is the horizontal coordinate parameter after rotation; y' is the vertical coordinate parameter after rotation; z' is the vertical coordinate parameter after rotation; x is the horizontal coordinate parameter before rotation; y is the vertical coordinate parameter before rotation; z is the vertical coordinate parameter before rotation; and θ is the rotation angle.

[0111] When the implicit curved surface of the support component is rotated, the formula for setting the rotation angle θ around the vertical axis is:

[0112]

[0113] When the implicit curved surface of the support component is rotated, the formula for setting the rotation angle θ in the vertical direction is:

[0114]

[0115] The implicit surface equation of the support can ensure the connection of all unit cells, and finally obtain the unit cell orientation model based on the implicit surface lattice structure.

[0116] like Figure 8 This is a visualization diagram of the three-point bending beam lattice of the support component according to an embodiment of the present invention; the figure shows the effect of replacing solid units with the optimally oriented implicit curved surface cells, and the connection between the cells is interconnected due to the presence of the skin.

[0117] Figures 9(a)-(f) are schematic diagrams of the layering and overall visualization of the three-dimensional lattice structure model of the support component of the present invention. Figure 9(a)-9(e) The unit cell orientations correspond to the optimal unit cell orientation information in Figures 6(a)-(e). The optimally oriented unit cells replace the solid units, and Boolean skins are used to achieve interconnection between the unit cells. Figure 9(f) shows a schematic diagram of the overall visualization of the three-dimensional lattice structure model, combined with... Figures 9(a)-9(e) The optimal orientation information of the unit cell is used to perform three-dimensional implicit curved surface unit cell substitution operations for solid unit cells.

[0118] Figures 10(a)-(b) show a comparison of the mechanical performance parameters of the original Gyroid lattice structure (Gyroid-2U) and the variable-direction Gyroid lattice structure (Gyroid-2G) photopolymerization models of the two-dimensional three-point bending beam support. The photopolymerization models of the original Gyroid lattice structure (Gyroid-2U) and the variable-direction Gyroid lattice structure (Gyroid-2G) of the two-dimensional three-point bending beam support in this embodiment of the invention are used to test and compare their mechanical performance parameters, thereby verifying the practicality of the invention. Two of the same type of model are printed.

[0119] Figures 11(a) and (b) show a comparison of the mechanical performance parameters of the original 3D Gyroid lattice structure (Gyroid-3U) and the variable-direction Gyroid lattice structure (Gyroid-3G) photopolymerization models of the support component. These two photopolymerization models were used to test and compare their mechanical performance parameters, thereby verifying the practicality of the invention. Two copies of each type of model were printed.

[0120] Figures 12(a)-(b) show the test curves of the mechanical performance parameters of the two-dimensional and three-dimensional homogeneous and variable-direction Gyroid lattice structures of the support component of the present invention, respectively. The test force-displacement curves were obtained by loading the loading point of the support component at a speed of 1 mm / s on a compression testing machine until the specimen fractured. The test curves of the mechanical performance parameters of the two-dimensional and three-dimensional homogeneous and variable-direction Gyroid lattice structures of the support component in the embodiment of the present invention show that the mechanical performance parameters of the variable-direction Gyroid lattice structure are superior to those of the original support component Gyroid lattice structure, which proves the reliability and superiority of the method of the present invention.

[0121] The beneficial effects of this invention are as follows: This invention provides a design method for an implicit curved surface variable-direction lattice structure of a support for additive manufacturing. During the design process, the anisotropy of the unit cells of the implicit curved surface lattice structure of the support is considered, i.e., the influence of the load direction on the mechanical performance parameters of the unit cells. This ensures that the principal stress direction of each unit is consistent with the direction of the lattice structure with stronger performance, thus improving the load-bearing capacity of the structure. Since changing the orientation of the unit cells in each region of the lattice structure due to the load transfer direction would destroy the original continuous curved surface of the implicit curved surface of the support, this problem is solved by arranging skins between the unit cells and using Boolean operations. This invention improves the support by changing the orientation of the original two-dimensional three-point bending beam Gyroid lattice structure and the original three-dimensional Gyroid lattice structure of the support, obtaining test curves of the mechanical performance parameters of the two-dimensional and three-dimensional homogeneous and variable-direction Gyroid lattice structures of the support. This verifies that the method can meet the actual application requirements and provides a solution for modeling variable-direction lattice structures.

[0122] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for designing implicit curved surface variable orientation lattice structures for support components in additive manufacturing, characterized in that: It includes: S1: Establish a 3D cell model of the implicit curved surface lattice structure of the support for additive manufacturing; Three-dimensional unit cell models with multiple rotation angles were established. Finite element simulation technology was used to analyze the mechanical properties of the unit cell models under each rotation direction, including deformation and stress. Anisotropy radar charts were provided, and the target rotation angle was determined. G ; S2: Determine the load transfer direction of the implicit curved surface lattice structure of the support component in the additive manufacturing process based on the force balance. S21: Establish a finite element solid model of the implicit curved surface lattice structure of the support component in the additive manufacturing process, perform mesh generation, apply constraints and loads, and number the generated elements. There are a total of n elements. S22: Based on the principle of force balance, extract the stress vectors of each element in the finite element solid model of the support component and store them in the dataset. In the middle, construct a two-dimensional planar structural stress vector model and a three-dimensional solid structural stress vector model of the support component; S23: Based on the stress vector model of the two-dimensional planar structure of the support component, the load transfer direction of each element in the two-dimensional solid model of the support component is determined as follows: ； in, For the first The load transfer direction of each unit; The angle between the stress vector along the horizontal axis and the horizontal direction; The angle between the stress vector along the vertical axis and the horizontal direction; This refers to the unit number in the solid model. n is the total number of entity model units; S24: Based on the three-dimensional structural stress vector model of the support, the load transfer direction of each element in the three-dimensional solid model of the support is determined as follows: ； in, For the first The load transfer direction of each unit number; The angle between the vertical stress vector and the horizontal vector; S3: Based on step S2, calculate the load transfer directions of all elements in the finite element solid model of the support component, and optimize the rotation direction of the implicit curved surface cell of the support component in step S1. Consistent with the load transfer direction of the corresponding unit, datasets of improved variable-direction lattice structures under two-dimensional and three-dimensional support structures are constructed respectively. S31: For the two-dimensional structure of the support member, the optimal rotation direction in step S1 is... In step S23, the load transfer direction of each element of the two-dimensional solid model of the support component is determined. Equal to obtain the rotation angle of the implicit curved surface lattice structure cell of the support, and store it in the improved variable orientation lattice structure dataset under the two-dimensional structure of the support. middle; S32: For the three-dimensional structure of the support component, the axis of rotation is the one with the smallest stress vector magnitude in the three coordinate directions, so that the load transfer direction of each element of the three-dimensional solid model of the support component determined in step S24 is determined. Rotation angle relative to the target in step S1 The obtained rotation axis information is stored in the improved variable orientation lattice structure dataset under the three-dimensional structure of the support component. middle; S4: Perform implicit surface modeling of the support component to complete the modeling of the implicit surface variable-direction lattice structure of the support component; perform Boolean merging between the skin and the improved variable-direction lattice structure dataset obtained in step S3 to achieve the connection and penetration between the unit cells of the implicit surface lattice structure of the support component, thereby obtaining the improved variable-direction implicit surface lattice structure of the support component with skin; the equation expression of the implicit surface lattice structure of the support component is: ； in, Parameters for controlling cell porosity; These are unit cell size parameters; The x-axis parameter; The ordinate parameter; These are the vertical coordinate parameters; By controlling the connection and penetration of all unit cells according to the implicit surface equation of the support, a unit cell orientation model of the implicit surface lattice structure of the support is obtained, which is used for additive manufacturing of the support.

2. The design method for an implicit curved surface variable orientation lattice structure of a support for additive manufacturing according to claim 1, characterized in that: The stress vector model for constructing the two-dimensional planar structure of the support component in step S2 is as follows: ； in, The direction of the force transmission path vector along the horizontal axis of the two-dimensional coordinate system; The direction of the force transmission path vector along the vertical axis of the two-dimensional coordinate system; Stress is in the transverse direction; The shear stresses are those along the horizontal and vertical axes. The shear stresses are those along the longitudinal and transverse axes; Stress along the longitudinal axis; and These are unit vectors along the horizontal and vertical axes, respectively.

3. The method for designing an implicit curved surface variable-direction lattice structure for additive manufacturing support members according to claim 2, characterized in that: The three-dimensional stress vector model of the support component in step S2 is as follows: ； in, The direction of the force transmission path vector along the horizontal axis of the three-dimensional coordinate system; The direction of the force transmission path vector along the vertical axis of the three-dimensional coordinate system; The direction of the force transmission path vector along the vertical axis of the three-dimensional coordinate system; The shear stresses are those along the vertical and horizontal axes. The shear stresses are those along the vertical and longitudinal axes. The shear stresses are those along the horizontal and vertical axes. The shear stresses are those along the longitudinal axis and the vertical axis. The stress is in the vertical direction; It is a unit vector in the vertical direction.

4. The method for designing an implicit curved surface variable-direction lattice structure for additive manufacturing support members according to claim 3, characterized in that: The angle between the stress vector in the transverse direction and the horizontal direction in step S2 The angle between the stress vector along the vertical axis and the horizontal direction Specifically: The angle between the stress vector in the transverse direction and the horizontal direction for: ； in, The angle between the stress vector along the horizontal axis and the horizontal direction; The angle between the stress vector along the longitudinal axis and the horizontal axis for: ； in, The angle between the stress vector along the vertical axis and the horizontal direction.

5. The method for designing an implicit curved surface variable-direction lattice structure for additive manufacturing support components according to claim 1, characterized in that: In step S4, implicit surface modeling of the support component is performed, specifically as follows: S41: Substitute the load transfer direction of each unit corresponding to the implicit curved surface cell of the support obtained in step S3 into the implicit curved surface equation of the support, perform unit cell surface modeling of the implicit curved surface lattice structure of the support, and obtain the expression of the implicit curved surface equation of the support. S42: Perform Boolean operations on the implicit surface lattice structure unit cell surface of the support member corresponding to each unit obtained in step S41 and the solid model in step S21 to obtain the closed structure of the implicit surface lattice structure unit cell of the support member, forming an independent space. After Boolean subtraction operation between the implicit surface of the support member and its solid structure, the support member Gyroid unit cell is obtained. All closed unit cells are matched with the unit positions of the support member solid model in step S21 to obtain a skinless variable orientation lattice structure. S43: Construct a skin structure with a thickness of 3mm and an overall size equal to that of the solid model of the support in step S21, and obtain the skinless variable orientation lattice structure constructed in S42. Adjust the position of the skin and the implicit curved surface lattice structure of the support to align them in space. Perform Boolean merging to achieve the connection between the cell and the skin, making them a whole, ensuring the connection of all cells, and obtaining the final implicit curved surface lattice structure of the variable orientation support with skin.

6. The method for designing an implicit curved surface variable orientation lattice structure for additive manufacturing support members according to claim 1, characterized in that: The implicit function expression of the implicit surface of the support member in step S4 is: ； The implicit function indicates that the period of the Gyroid surface of the support is the same in the three coordinate axes of the three-dimensional coordinate system and is equal to 5. That is, the size of the unit cell of the Gyroid support is 5mm×5mm×5mm. The equivalent parameter t of the implicit function of the Gyroid surface of the support is 0, that is, the porosity is 50%.

7. The method for designing an implicit curved surface variable-direction lattice structure for additive manufacturing support members according to claim 1, characterized in that: In step S4, when the implicit curved surface of the support member is rotated, the rotation angle of the horizontal axis is set to be... The formula for time is: ； in, The x-coordinate parameter after rotation; These are the ordinate parameters after rotation; These are the vertical coordinate parameters after rotation; The x-coordinate parameter before rotation; The ordinate parameter before rotation; These are the vertical coordinate parameters before rotation; The angle is the rotation angle.

8. The method for designing an implicit curved surface variable orientation lattice structure for additive manufacturing support members according to claim 7, characterized in that: In step S4, when the implicit curved surface of the support member is rotated, the rotation angle of the longitudinal axis is set to be... The formula for time is: 。 9. The method for designing an implicit curved surface variable orientation lattice structure for additive manufacturing support members according to claim 7, characterized in that: In step S4, when the implicit curved surface of the support member is rotated, the rotation angle in the vertical direction is set to be... The formula for time is: 。 10. The method for designing an implicit curved surface variable orientation lattice structure for additive manufacturing support members according to claim 1, characterized in that: The multiple rotation angles are 0 degrees, 15 degrees, 22.5 degrees, 30 degrees and 45 degrees.

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