Third-period minimum curved surface porous structure design method based on force field self-adaption

Abstract

The invention discloses a force field self-adaption-based three-time period minimum curved surface porous structure design method, and relates to the field of computer aided design. Comprising the following steps: S1, designing a three-time period minimum curved surface unit with a set wall thickness; s2, preparing a third-period minimum curved surface unit entity structure; s3, establishing a constitutive relationship between the solid structure characteristics and mechanical properties of the minimum curved surface unit in the third period; and S4, analyzing the mechanical state of the to-be-designed object in the actual application scene. By constructing a high-precision constitutive relation between solid structure characteristics and mechanical properties of a minimum curved surface unit in a three-time period and combining with force field distribution data in an actual application scene, local self-adaptive regulation and control of the wall thickness and porosity of the porous structure are realized, so that the bearing capacity of the structure is automatically enhanced in a high-stress area, and the performance of the structure is improved. And the weight is effectively reduced in a low-stress area, so that the utilization efficiency of materials is remarkably improved on the premise of ensuring the overall mechanical property.

Description

Technical Field

[0001] This invention relates to the field of computer-aided design, and in particular to a method for designing a cubic periodic minimum surface porous structure based on force field adaptation. Background Technology

[0002] With the increasing application of advanced porous materials in biomedical implants, lightweight engineering components, and thermal management devices, triple periodic minimal surfaces (TPMS) have become an important foundation for the design of next-generation functional porous materials due to their excellent properties such as continuous smooth geometry, high specific strength, large specific surface area, and dual-channel structure. TPMS structures not only possess excellent mechanical load-bearing capacity but also exhibit unique advantages in multi-physics coupling scenarios such as fluid transport, cell attachment, and heat exchange. Therefore, they are widely regarded as the ideal topological configuration for high-performance structure-function integrated materials.

[0003] Among them, the design of porous structures based on TPMS usually relies on preset geometric parameters, such as setting a fixed wall thickness or a linear gradient wall thickness to construct a homogeneous or simple gradient structure. Although such methods can achieve basic porosity control, their design logic is essentially detached from the dynamic distribution characteristics of complex mechanical loads in actual service environments, making it difficult to achieve refined topology optimization that matches the local stress or strain state within the structure.

[0004] In existing technologies, the design of TPMS structures generally lacks a mechanism for relating it to the force field distribution in the application scenario. This can lead to issues such as strength redundancy or insufficient load-bearing capacity in critical stress areas of the generated porous structures. Furthermore, traditional design processes do not establish quantitative constitutive relationships between structural parameters (such as wall thickness and porosity) and macroscopic mechanical properties (such as compressive strength and modulus), failing to support adaptive structure generation under specific load conditions. Moreover, even if additive manufacturing technology can achieve the molding of complex TPMS configurations, without a design closed loop driven by measured mechanical data, it is still difficult to ensure the performance reliability and functional adaptability of the structure under real-world working conditions. Therefore, there is an urgent need for an adaptive design method that can dynamically adjust the local topology of TPMS based on the actual force field to achieve a precise and integrated match between materials, structure, and function. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a force-field adaptive design method for cubic periodic minimum surface porous structures, which can effectively solve the problems mentioned in the background. Existing designs for cubic periodic minimum surface porous structures generally rely on preset geometric parameters, lacking a dynamic correlation mechanism with the complex mechanical load distribution in actual service environments. This leads to strength redundancy or insufficient load-bearing capacity in key stress areas, and the absence of a quantitative constitutive relationship between structural parameters and macroscopic mechanical properties makes it difficult to achieve adaptive topology optimization for specific load conditions.

[0006] This invention provides a method for designing a cubic periodic minimum surface porous structure based on force field adaptation, comprising: S1. Design a cubic periodic minimum surface element with a given wall thickness; using computer-aided design software, based on the cubic periodic minimum surface of type Gyroid, Primitive, Neovius, Lidinoid, Split P or Diamond, generate cubic periodic minimum surface elements with different wall thicknesses or porosities based on the principle of equal wall thickness or equal porosity. S2. Prepare a solid structure of a cubic periodic minimum surface unit; select polymer, metal or ceramic materials, and use selective laser sintering, photopolymerization molding or material extrusion manufacturing technology to solidify the cubic periodic minimum surface unit to generate a solid structure of a cubic periodic minimum surface unit; S3. Establish constitutive relations between the structural characteristics and mechanical properties of cubic periodic minimum surface unit solid structures; conduct compression experiments on the cubic periodic minimum surface unit solid structures to obtain their compressive strength and compressive modulus, and combine the wall thickness and porosity in the design stage to construct a quantitative functional relationship between compressive strength or compressive modulus and wall thickness and porosity. S4. Analyze the mechanical state of the object to be designed in the actual application scenario; obtain the stress field distribution or strain field distribution of the object to be designed under service conditions through finite element simulation or digital image correlation analysis tools, and convert the strain field into an equivalent stress field based on the material elastic modulus; S5. Based on the stress field distribution and the constitutive relationship, perform force field adaptive cubic periodic minimum surface porous structure design; divide the object to be designed into multiple local regions, determine the corresponding local wall thickness or porosity by interpolation calculation according to the stress value of each region, and fill the corresponding region with cubic periodic minimum surface elements with corresponding parameters to generate an adaptive porous structure.

[0007] Specifically, S1 includes: The design range of the differential wall thickness is from 0 mm to the critical wall thickness value that makes the porosity approach 0%. For a Gyroid unit with a side length of 6 mm, the critical wall thickness is 3 mm. The wall thickness range is divided into six equal parts with a tolerance of 0.6 mm, generating unit structures with wall thickness sequences of 0 mm, 0.6 mm, 1.2 mm, 1.8 mm, 2.4 mm, and 3.0 mm.

[0008] Specifically, S1 further includes: The design range of arithmetic porosity is 0% to 100%, divided into six equal parts with a tolerance of 20%, generating unit structures with porosity sequences of 0%, 20%, 40%, 60%, 80%, and 100%, corresponding to wall thicknesses of 0mm, 0.41mm, 0.82mm, 1.25mm, 1.80mm, and 3.20mm after geometric conversion. Porosity was calculated using a voxelization method, which discretized the unit structure into a cubic mesh with a side length of 0.01 mm and calculated the ratio of solid voxels to the total number of meshes.

[0009] Specifically, in S2, when the selected material is calcium phosphate ceramic, it is prepared using photocuring molding technology. The mass fraction of calcium phosphate powder in the photosensitive resin is 60%, the thickness of the cured layer is 25 μm, and the density after sintering is greater than 95%.

[0010] Specifically, S3 includes: For brittle materials like calcium phosphate ceramics, a constitutive relationship between wall thickness and compressive strength is established using ultimate strength as an index of compressive strength. The mathematical expression is as follows: ; For polyurethane polymer plastic materials, using yield strength as an index of compressive strength, the mathematical expression of its constitutive relation is as follows: ; In the formula, For compressive strength, For wall thickness; among them, for brittle materials such as calcium phosphate ceramics, the correlation of variables is... The correlation coefficient is 0.999 for polyurethane polymer plastic materials. It is 0.997.

[0011] Specifically, in S4, the finite element simulation uses tetrahedral second-order elements for mesh generation, with a mesh size not exceeding 0.5 mm. The boundary conditions are consistent with the actual load conditions, and the solver convergence tolerance is set to [value missing]. .

[0012] Specifically, in S4, the digital image correlation analysis uses a high-speed camera to collect the deformation process of the object under force, calculates the full-field displacement through a cross-correlation algorithm, obtains the strain field by differentiating the strain tensor, and finally converts it into a stress field by combining the Young's modulus of the material.

[0013] Specifically, in S5, the local region is divided using an octree spatial segmentation algorithm, which adaptively adjusts the region size based on the stress gradient, generating smaller sub-regions in regions with drastic stress changes, with the minimum region side length not less than the period length of a single cubic periodic minimum surface element.

[0014] Specifically, in S5, the interpolation calculation adopts the cubic spline interpolation method to ensure that the wall thickness variation between adjacent regions is continuous and differentiable. The input of the interpolation function is the local average stress value, and the output is the corresponding wall thickness value. The mapping relationship is obtained by inverting the constitutive relation.

[0015] Specifically, the adaptive porous structure generated in S5 has a wall thickness of not less than 1.5 mm in the high-stress region and not more than 0.6 mm in the low-stress region, with an overall porosity gradient ranging from 30% to 85%.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention constructs a high-precision constitutive relationship between the structural characteristics and mechanical properties of cubic periodic minimum surface units, and combines this with force field distribution data from real-world application scenarios to achieve local adaptive control of the wall thickness and porosity of porous structures. This overcomes the limitations of traditional fixed-parameter or linear gradient designs, enabling the structure to automatically enhance its load-bearing capacity in high-stress regions and effectively reduce weight in low-stress regions, thereby significantly improving material utilization efficiency while ensuring overall mechanical performance. Furthermore, this invention establishes a complete design closed loop from material properties and structural parameters to macroscopic mechanical response, supporting various material systems such as polymers, metals, and ceramics. It is applicable to complex working conditions such as bio-implants, lightweight components, and heat exchangers, significantly improving the functional adaptability and engineering practicality of cubic periodic minimum surface porous structures. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a design method for a cubic periodic minimum surface porous structure based on force field adaptation.

[0018] Figure 2 This is a structural diagram of the main unit types of TPMS.

[0019] Figure 3 This is a schematic diagram of the structure of a TPMS-Gyroid unit with an equal wall thickness of 6 mm.

[0020] Figure 4This is a schematic diagram of a TPMS-Gyroid unit with a porosity of 6 mm and an arithmetic gradient. Figure 5 The constitutive relationship curve between the wall thickness and compressive strength of the calcium phosphate TPMS unit structure is shown in the figure.

[0021] Figure 6 This is a constitutive relationship curve between the wall thickness and compressive strength of a polyurethane polymer TPMS unit structure.

[0022] Figure 7 This is a stress field distribution diagram of a square block of calcium phosphate.

[0023] Figure 8 This is a diagram showing the stress field distribution of the shoe sole under different stress conditions.

[0024] Figure 9 For based on Figure 7 The diagram shows the cubic periodic minimum surface porous structure of the TPMS block.

[0025] Figure 10 For based on Figure 8 Diagram of the three-period minimum curved porous structure of the TPMS shoe sole. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0027] Example 1 To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0028] Currently, advanced porous materials are widely used in biomedical implants, lightweight engineering components, and thermal management devices. Cubic periodic minimum surfaces, due to their continuous smooth geometry, high specific strength, large specific surface area, and dual-channel structure, have become a crucial foundation for the design of next-generation functional porous materials. Porous structure design based on cubic periodic minimum surfaces typically relies on preset geometric parameters, such as setting a fixed wall thickness or linear gradient wall thickness to construct homogeneous or simple gradient structures. While such methods can achieve basic porosity control, their design logic is fundamentally detached from the dynamic distribution characteristics of complex mechanical loads in actual service environments, making it difficult to achieve refined topology optimization that matches local stress or strain states within the structure. In existing technologies, the design of cubic periodic minimum surface structures generally lacks a correlation mechanism with the force field distribution in the application scenario, leading to potential strength redundancy or insufficient load-bearing capacity in critical stress areas of the generated porous structures. Furthermore, traditional design processes do not establish a quantitative constitutive relationship between structural parameters and macroscopic mechanical properties, failing to support adaptive structure generation under specific load conditions. Furthermore, even though additive manufacturing technology can achieve the molding of complex cubic periodic minimum surface configurations, without a design closed loop driven by measured mechanical data, it is still difficult to ensure the performance reliability and functional adaptability of the structure under real working conditions. To address these technical problems, this invention proposes to construct a high-precision constitutive relationship between the structural characteristics and mechanical properties of cubic periodic minimum surface units, and combine this with force field distribution data from actual application scenarios to achieve local adaptive control of the wall thickness and porosity of porous structures. This is then applied to a force field adaptive cubic periodic minimum surface porous structure design method. Figure 1 As shown, the method includes: S1. Design a cubic periodic minimum surface element with a given wall thickness; using computer-aided design software, based on the cubic periodic minimum surface of type Gyroid, Primitive, Neovius, Lidinoid, Split P or Diamond, generate cubic periodic minimum surface elements with different wall thicknesses or porosities based on the principle of equal wall thickness or equal porosity. S2. Prepare a solid structure of a cubic periodic minimum surface unit by selecting polymer, metal or ceramic materials and using selective laser sintering, photopolymerization molding or material extrusion manufacturing technology to solidify the cubic periodic minimum surface unit to generate a solid structure of a cubic periodic minimum surface unit. S3. Establish constitutive relations between the structural characteristics and mechanical properties of cubic periodic minimum surface unit solid structures; conduct compression experiments on the cubic periodic minimum surface unit solid structures to obtain their compressive strength and compressive modulus, and combine the wall thickness and porosity in the design stage to construct a quantitative functional relationship between compressive strength or compressive modulus and wall thickness and porosity. S4. Analyze the mechanical state of the object to be designed in the actual application scenario. Use finite element simulation or digital image correlation analysis tools to obtain the stress field distribution or strain field distribution of the object to be designed under service conditions, and convert the strain field into an equivalent stress field based on the material elastic modulus. S5. Based on the stress field distribution and the constitutive relationship, a force field adaptive cubic periodic minimum surface porous structure design is carried out. The object to be designed is divided into multiple local regions. According to the stress value of each region, the corresponding local wall thickness or porosity is determined by interpolation calculation. The corresponding region is filled with cubic periodic minimum surface elements with corresponding parameters to generate an adaptive porous structure that is continuous as a whole and whose mechanical properties match the load distribution.

[0029] Specifically, S1 includes: The cubic periodic minimum surface basis includes: Gyroid elements, Primitive elements, Neovius elements, Lidinoid elements, Split P elements, and Diamond elements, such as... Figure 2 As shown.

[0030] The design range for the differential wall thickness is from 0 mm to the critical wall thickness value that makes the porosity approach 0%. For a Gyroid unit with a side length of 6 mm, the critical wall thickness is 3 mm. The wall thickness range is divided into six equal parts with a tolerance of 0.6 mm, generating unit structures with wall thickness sequences of 0 mm, 0.6 mm, 1.2 mm, 1.8 mm, 2.4 mm, and 3.0 mm. Figure 3 As shown; in the wall thickness sequence, the unit with a wall thickness of 0 mm corresponds to a completely open skeleton structure, while the unit with a wall thickness of 3.0 mm corresponds to a solid-filled state with porosity approaching 0%. All unit structures are constructed using parametric modeling, and their geometric expressions are based on implicit function definitions. For example, the mathematical expression for a Gyroid surface is... The wall thickness is achieved by offsetting an implicit surface along the normal direction of the curved surface. The offset operation is numerically solved using the level set method to ensure uniform wall thickness and a continuous and smooth surface. The period length of the unit structure is uniformly set to 6mm to ensure geometric compatibility during subsequent space filling.

[0031] The arithmetic porosity design range is 0% to 100%, divided into six equal parts with a tolerance of 20%, generating unit structures with porosity sequences of 0%, 20%, 40%, 60%, 80%, and 100%, as shown below. Figure 4As shown, the corresponding wall thicknesses, after geometric conversion, are 0 mm, 0.41 mm, 0.82 mm, 1.25 mm, 1.80 mm, and 3.20 mm. Porosity was calculated using a voxelization method, discretizing the unit structure into a cubic mesh with a side length of 0.01 mm. The ratio of solid voxels to the total mesh number was statistically analyzed, achieving a calculation accuracy better than 0.1%. All generated unit structures were exported in STL format for subsequent additive manufacturing.

[0032] Specifically, S2 includes: When calcium phosphate ceramic was selected as the material, it was prepared using photopolymerization molding technology. The photosensitive resin contained 60% calcium phosphate powder by mass, the cured layer thickness was 25 μm, and the density after sintering was greater than 95%. The preparation process first involved mixing calcium phosphate powder and photosensitive resin at a mass ratio of 60:40, then ball milling and dispersing for 2 hours to form a uniform slurry, which was then loaded into the material tank of the photopolymerization equipment. The equipment used a 385 μm wavelength ultraviolet light source, a single-layer exposure energy density of 50 mJ / cm², and an interlayer delay time of 10 s to ensure complete curing. After printing, the green body was cleaned with isopropanol to remove uncured resin, then post-cured at 120°C for 2 hours, and finally sintered in air at 1300°C for 4 hours at a heating rate of 2°C / min. The measured sintering shrinkage rate was 18%, which had been corrected for through dimensional compensation during the design phase.

[0033] For polyurethane polymer materials, an extrusion process was used with a nozzle diameter of 0.4 mm, an extrusion temperature of 220°C, a printing speed of 50 mm / s, and a layer thickness of 0.2 mm. All prepared unit structures underwent dimensional accuracy testing, with key geometric features measured using an optical 3D scanner. Errors were controlled within ±0.05 mm to ensure the reliability of the experimental data.

[0034] Specifically, S3 includes: For brittle materials like calcium phosphate ceramics, a constitutive relationship between wall thickness and compressive strength is established using ultimate strength as an index of compressive strength, such as... Figure 5 As shown, the mathematical expression is as follows: ; For polyurethane polymer plastic materials, yield strength is used as an indicator of compressive strength, such as Figure 6 As shown, the mathematical expression for its constitutive relation is as follows: ; In the formula, For compressive strength, For wall thickness; among them, for brittle materials such as calcium phosphate ceramics, the correlation of variables is... The correlation coefficient is 0.999 for polyurethane polymer plastic materials. It is 0.997.

[0035] Compression tests were conducted according to ISO 13314 standard. The specimens were cylinders with a diameter of 12 mm and a height of 18 mm, constructed from multiple identical stacked and bonded unit structures. The tests were performed on a universal testing machine at a loading rate of 0.5 mm / min until specimen failure or the maximum load was reached. Each wall thickness level was tested five times, and the average value was taken as the final result. The compressive modulus was calculated from the slope of the initial linear segment of the stress-strain curve. All experimental data were fitted using the least squares method to obtain a constitutive relation in power function form. The high correlation of this constitutive relation verifies the decisive influence of wall thickness as the dominant parameter on mechanical properties.

[0036] Furthermore, there is a deterministic geometric mapping between porosity and wall thickness, which can be expressed by numerical integration or empirical formulas, thus supporting the construction of a constitutive model with porosity as the independent variable. The establishment of constitutive relations provides a mathematical basis for subsequent force field-driven parameter mapping.

[0037] Specifically, S4 includes: The finite element simulation uses tetrahedral second-order elements for mesh generation, with a mesh size no larger than 0.5 mm. The boundary conditions are consistent with the actual load conditions, and the solver convergence tolerance is set to [value missing]. This ensures that the accuracy error of the stress field distribution is less than 2%.

[0038] The simulation was performed in commercial finite element software. The material properties used were the compressive modulus measured in S3. For porous materials where isotropy is assumed, the relationship between Young's modulus and compressive modulus is as follows: ,in, For Young's modulus, For compression modulus, Poisson's ratio Take 0.3.

[0039] The load conditions are set according to the specific application scenario. For example, based on a cubic calcium phosphate block, under a given stress environment, the stress-strain field distribution is captured through simulation. Figure 7 As shown. Based on the sole, the stress field distribution under different foot stress states is simulated using finite element method, such as... Figure 8 As shown. After the solution is completed, the Mises equivalent stress distribution within the entire object domain is extracted as the input data field for subsequent mapping.

[0040] Furthermore, the digital image correlation analysis in S4 employs a high-speed camera to capture the deformation process of an object under stress at a rate of 1000 frames per second, with an image resolution of 2048 x 2048 pixels. The full-field displacement is calculated using a cross-correlation algorithm, and the strain field is obtained by differentiating the strain tensor. Finally, the stress field is converted using the Young's modulus of the material. This method is suitable for scenarios with existing physical prototypes, allowing for the acquisition of real deformation data through experimental means. The image acquisition system is equipped with a dual-camera stereo vision configuration, with a calibration error of less than 0.01 pixels. The displacement field calculation uses a cross-correlation algorithm with a sub-region size of 32 pixels and a step size of 4 pixels. The strain field is obtained through local polynomial fitting and differentiation, with a spatial resolution of 0.5 mm. Both methods can generate high-resolution stress field data, whose spatial distribution is stored in the form of a three-dimensional scalar field, with each spatial point containing coordinates (x, y, z) and the corresponding stress value.

[0041] Specifically, S5 includes: The local region is divided using an octree spatial segmentation algorithm, which adaptively adjusts the region size based on the stress gradient. Smaller sub-regions are generated in areas of drastic stress change, with the smallest region having a side length no less than the period length of a single cubic periodic minimum surface element. The octree segmentation starts from the object's bounding box and recursively subdivides until either of the following conditions is met: the sub-region side length is less than 6mm (i.e., the element period length), or the maximum stress gradient within the sub-region is less than a preset threshold. The average internal stress of each leaf node region is calculated as the representative stress.

[0042] Subsequently, the interpolation calculation employs cubic spline interpolation to ensure continuous and differentiable wall thickness variations between adjacent regions, avoiding stress concentration caused by abrupt structural changes. The input to the interpolation function is the local average stress value, and the output is the corresponding wall thickness value. This mapping relationship is obtained by inverting the constitutive relation. For example, for a cubic block of calcium phosphate or a shoe sole, from... Inverse solution The inversion function exhibits monotonicity and smoothness within the effective stress range (corresponding to wall thicknesses of 0.4 to 2.8 mm), making it suitable for spline interpolation. The interpolation process is performed at the center points of all leaf node regions, generating a discrete wall thickness field. A continuous wall thickness distribution function is then obtained through cubic spline surface fitting. Ultimately, this function is used to drive the local wall thickness shift of a cubic periodic minimum surface, generating an adaptive porous structure, such as... Figure 9 and Figure 10 As shown.

[0043] The adaptive porous structure generated in S5 has a wall thickness of no less than 1.5 mm in high-stress regions and no more than 0.6 mm in low-stress regions, with an overall porosity gradient ranging from 30% to 85%, satisfying the dual design goals of lightweighting and localized strengthening. The structure generation employs implicit modeling technology, incorporating the wall thickness field... As an offset function, the implicit equation of the basic cubic periodic minimum surface is spatially varied and offset, ensuring that the surface is globally continuous and free from self-intersection. The generated model is output in the form of high-resolution voxels or NURBS surfaces, which are suitable for subsequent manufacturing.

[0044] Example 2 Based on Example 1, an alternative technical solution is considered, in which the establishment of constitutive relations not only depends on wall thickness, but also introduces porosity as a second independent variable to construct a bivariate function model.

[0045] Specifically, in S1, a two-dimensional parameter matrix covering wall thicknesses of 0.5 to 2.5 mm and porosities of 40% to 80% was simultaneously generated, resulting in a total of 49 unit structures. In S2, titanium alloy units were prepared using selective laser melting (SLM) with a laser power of 280 W, a scanning speed of 1200 mm / s, a layer thickness of 30 μm, and argon as the protective gas with an oxygen content below 500 ppm. In S3, compression experiments were conducted on all 49 unit structures to obtain compressive strength data, which was then fitted using multivariate nonlinear regression to obtain... Bivariate constitutive relations, for example Where a, b, and c are fitting coefficients. Porosity is used to more accurately describe the material-structure coupling effect, especially suitable for material systems where porosity significantly affects mechanical properties. In S5, the mapping from stress field to structural parameters requires solving for both wall thickness and porosity simultaneously, using a two-dimensional interpolation algorithm (such as bicubic splines). Mapping is performed on the parameter plane, and the local region division strategy is the same as in Example 1, but each region needs to determine a pair of... This solution is applicable to scenarios where porosity has independent functional requirements, such as bone implants where mechanical strength and bone ingrowth porosity need to be controlled simultaneously. The remaining steps are consistent with Example 1, including manufacturing, post-processing, and closed-loop verification. Example 2 demonstrates the extended capabilities of this invention in multi-parameter collaborative optimization, further improving design freedom and functional adaptation accuracy.

[0046] All content not described in detail in this specification is prior art known to those skilled in the art, and the model parameters of each electrical appliance are not specifically limited; conventional equipment can be used. Electrical control components not mentioned in this technical solution are not shown in the figures because they are prior art, and will not be described further here.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a cubic periodic minimum surface porous structure based on force field adaptation, characterized in that, include: S1. Design a cubic periodic minimum surface element with a given wall thickness; Using computer-aided design software, based on the three-dimensional periodic minimum surface of type Gyroid, Primitive, Neovius, Lidinoid, Split P or Diamond, and based on the principle of equal wall thickness or equal porosity, three-dimensional periodic minimum surface elements with different wall thicknesses or porosities are generated. S2. Prepare a solid structure of a cubic periodic minimum surface unit; select polymer, metal or ceramic materials, and use selective laser sintering, photopolymerization molding or material extrusion manufacturing technology to solidify the cubic periodic minimum surface unit to generate a solid structure of a cubic periodic minimum surface unit; S3. Establish constitutive relations between the structural characteristics and mechanical properties of cubic periodic minimum surface unit solid structures; conduct compression experiments on the cubic periodic minimum surface unit solid structures to obtain their compressive strength and compressive modulus, and combine the wall thickness and porosity in the design stage to construct a quantitative functional relationship between compressive strength or compressive modulus and wall thickness and porosity. S4. Analyze the mechanical state of the object to be designed in the actual application scenario; By using finite element simulation or digital image correlation analysis tools, the stress field distribution or strain field distribution of the object under service conditions is obtained, and the strain field is converted into an equivalent stress field based on the material's elastic modulus. S5. Based on the stress field distribution and the constitutive relationship, perform force field adaptive cubic periodic minimum surface porous structure design; divide the object to be designed into multiple local regions, determine the corresponding local wall thickness or porosity by interpolation calculation according to the stress value of each region, and fill the corresponding region with cubic periodic minimum surface elements with corresponding parameters to generate an adaptive porous structure.

2. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 1, characterized in that: S1 includes: The design range of the differential wall thickness is from 0 mm to the critical wall thickness value that makes the porosity approach 0%. For a Gyroid unit with a side length of 6 mm, the critical wall thickness is 3 mm. The wall thickness range is divided into six equal parts with a tolerance of 0.6 mm, generating unit structures with wall thickness sequences of 0 mm, 0.6 mm, 1.2 mm, 1.8 mm, 2.4 mm, and 3.0 mm.

3. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 2, characterized in that: The S1 further includes: The design range of arithmetic porosity is 0% to 100%, divided into six equal parts with a tolerance of 20%, generating unit structures with porosity sequences of 0%, 20%, 40%, 60%, 80%, and 100%, corresponding to wall thicknesses of 0mm, 0.41mm, 0.82mm, 1.25mm, 1.80mm, and 3.20mm after geometric conversion. Porosity was calculated using a voxelization method, which discretized the unit structure into a cubic mesh with a side length of 0.01 mm and calculated the ratio of solid voxels to the total number of meshes.

4. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 3, characterized in that: In S2, when the selected material is calcium phosphate ceramic, it is prepared by photocuring molding technology. The mass fraction of calcium phosphate powder in the photosensitive resin is 60%, the thickness of the cured layer is 25μm, and the density after sintering is greater than 95%.

5. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 4, characterized in that: The S3 includes: For brittle materials like calcium phosphate ceramics, a constitutive relationship between wall thickness and compressive strength is established using ultimate strength as an index of compressive strength. The mathematical expression is as follows: ； For polyurethane polymer plastic materials, using yield strength as an index of compressive strength, the mathematical expression of its constitutive relation is as follows: ； In the formula, For compressive strength, For wall thickness; among them, for brittle materials such as calcium phosphate ceramics, the correlation of variables is... The correlation coefficient is 0.999 for polyurethane polymer plastic materials. It is 0.

997.

6. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 1, characterized in that: In step S4, the finite element simulation uses tetrahedral second-order elements for mesh generation, with a mesh size not exceeding 0.5 mm. The boundary conditions are consistent with the actual load conditions, and the solver convergence tolerance is set to [value missing]. .

7. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 1, characterized in that: In S4, the digital image correlation analysis uses a high-speed camera to collect the deformation process of the object under force, calculates the full-field displacement through a cross-correlation algorithm, obtains the strain field by differentiating the strain tensor, and finally converts it into a stress field by combining the Young's modulus of the material.

8. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 1, characterized in that: In S5, the local region is divided using an octree spatial segmentation algorithm. The region size is adaptively adjusted according to the stress gradient, and smaller sub-regions are generated in regions with drastic stress changes. The side length of the smallest region is not less than the period length of a single cubic periodic minimum surface element.

9. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 8, characterized in that: In S5, the interpolation calculation adopts the cubic spline interpolation method to ensure that the wall thickness change between adjacent regions is continuous and differentiable. The input of the interpolation function is the local average stress value, and the output is the corresponding wall thickness value. The mapping relationship is obtained by inversion of the constitutive relation.

10. The method for designing a cubic periodic minimum surface porous structure based on force field adaptation according to claim 8, characterized in that: The adaptive porous structure generated in S5 has a wall thickness of not less than 1.5 mm in the high-stress region and not more than 0.6 mm in the low-stress region, with an overall porosity gradient ranging from 30% to 85%.

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