Method and system for manufacturing a shoe with a variable gradient porous structure based on stress

Abstract

The application discloses a preparation method and system of a shoe with a variable gradient porous structure based on stress, and belongs to the technical field of 3D printing, and comprises the following steps: scanning a foot shape to generate a shoe contour shape; collecting stress distribution of a foot bottom, obtaining boundary distribution of the stress of the foot bottom through boundary fitting, and generating a stress function area; fitting the stress function area into the shoe contour shape, obtaining gradient transition changes according to the size relationship between the stresses between the stress function areas, and generating a gradient change area of the shoe contour shape; and based on 3D printing technology, printing the shoe contour shape with the stress function area and the gradient change area into a shoe with a Gyroid variable gradient porous structure and suitable for the foot shape based on an elastic material such as TPU. The application proposes an application method of a human foot shape and a foot stress measurement method in shoe design, and increases the service range of 3D printing customization.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and more specifically, to a method and system for fabricating stress-based shoes with a variable gradient porous structure. Background Technology

[0002] 3D printing is a type of rapid prototyping technology, also known as additive manufacturing. It is a technology that uses digital model files as a basis and employs powdered metal or plastic and other bondable materials to construct objects by printing layer by layer.

[0003] Porous materials are materials that consist of a network structure of interconnected or closed pores. The boundaries or surfaces of the pores are formed by pillars or plates. Compared with continuous media materials, porous materials generally have advantages such as low relative density, high specific strength, high specific surface area, light weight, sound insulation, heat insulation, and good permeability.

[0004] 3D printing technology can be used to print porous materials into shoes. Compared with other custom shoes, this not only reduces costs and shortens the production cycle, but also, due to the strong adaptability of porous materials, can achieve functions such as shock absorption, torsion resistance, wear resistance, rebound, and breathability through different structures. However, existing technologies do not have the relevant technical design. Therefore, there is an urgent need to design a method for manufacturing shoes with stress-based variable gradient porous structures, and to realize the manufacturing of multifunctional custom shoes through 3D printing technology. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a stress-based fabrication technology for shoes with a random variable gradient porous structure. This technology combines finite element analysis with 3D printing, utilizing 3D scanning to scan the user's foot morphology and generate a suitable shape; a foot pressure tester to generate a stress distribution map; and parametric modeling to arrange various minimum surface lattice units according to the stress distribution using a deformation gradient, forming the shoe's body, sole, insole, and other structures.

[0006] To achieve the above-mentioned technical objectives, this application provides a method for fabricating a stress-based shoe with a variable gradient porous structure, comprising the following steps:

[0007] Scan the shape of the foot to generate the outline of the shoe;

[0008] The stress distribution on the sole of the foot is collected, and the boundary distribution of the stress on the sole of the foot is obtained through boundary fitting. Stress functional regions are generated, which are used to adapt to the stress distribution on the sole of the foot.

[0009] The stress functional areas are fitted to the shoe outline, and the gradient transition changes are obtained based on the magnitude relationship between the stresses in the stress functional areas, thus generating the gradient change area of ​​the shoe outline.

[0010] Based on 3D printing technology, the shoe outline with stress functional areas and gradient change areas is printed into a shoe with a Gyroid variable gradient porous structure that is suitable for the shape of the foot using Gyroid porous material. Here, Gyroid porous material is used to represent an elastic material with a Gyroid porous structure.

[0011] Preferably, in the process of obtaining the boundary distribution of plantar stress, point cloud extraction is performed by obtaining stress distribution maps at various points on the sole of the foot, and the initial range boundary of plantar stress distribution is obtained by analyzing the point cloud density.

[0012] By performing bivariate nth-order spline fitting on the initial range boundary, the boundary distribution of plantar stress is obtained, where n is an integer greater than or equal to 3.

[0013] Preferably, in the process of generating stress functional zones, based on the boundary distribution of plantar stress, the maximum stress value is obtained to obtain an adjustment factor for characterizing the impact of stress value on comfort.

[0014] By adjusting the adjustment factor, the comfort level of different stress areas is adjusted, thus generating stress functional zones.

[0015] Preferably, in the process of obtaining the regulation factor, the regulation factor is expressed as:

[0016]

[0017] Where max represents the maximum stress value, and Y[g(x, y, z)] represents the stress value on the corresponding boundary.

[0018] Preferably, in the process of generating the stress functional zone, the stress functional zone includes a high resilience zone and a hard support zone, wherein the high resilience zone is adapted to the minimum stress value, and the hard support zone is adapted to the maximum stress value.

[0019] Preferably, in the process of obtaining the gradient change region, the gradient change region is represented as:

[0020] Fn(x,y,z)=s(x,y,z)·F1(x,y,z)+(1-s(x,y,z))·F2(x,y,z)

[0021] Where s(x, y, z) is the stress boundary between two stress functional zones, F1(x, y, z) is the spatial expression of one stress functional zone, and F2(x, y, z) represents the spatial expression of another stress functional zone that is different from F1(x, y, z).

[0022] Preferably, in the process of obtaining the stress boundary, the stress boundary is used to control the smooth transition of the gradient between the two stress functional regions, and is expressed as:

[0023]

[0024] In the formula, g(x, y, z) represents the spatial graphic function of the stress functional region, and α represents the determinant of the gradient transition rate. Where g = x 2 +y 2 +z 2 -r 2 When this occurs, a gradient transition is formed between the stress functional zones on the surface of a sphere with a spatial radius of r.

[0025] Preferably, in the process of using Gyroid porous structure material, the pore size of Gyroid porous structure material is set at 200-1000 micrometers, preferably 500 micrometers.

[0026] Preferably, in the process of printing shoes suitable for the shape of the foot, a high-resilience zone is prepared using a high-porosity Gyroid porous material, a rigid support zone is prepared using a low-porosity Gyroid porous material, and a gradient zone is prepared using a Gyroid porous material with gradient-varying porosity. The high porosity is 50-80%, preferably 65%; the low porosity is 20-50%, preferably 45%; and the gradient porosity ranges from 20-80%, preferably 45%-65%.

[0027] This invention discloses a stress-based fabrication system for shoes with a variable gradient porous structure, and a method for fabricating shoes with a variable gradient porous structure, comprising:

[0028] The scanning module is used to scan the shape of the foot and generate the outline of the shoe.

[0029] The stress functional zone division module is used to collect the stress distribution of the plantar surface, obtain the boundary distribution of the stress of the plantar surface through boundary fitting, and generate stress functional zones. The stress functional zones are used to adapt to the stress distribution of the plantar surface.

[0030] The gradient change region segmentation module is used to fit the stress functional region to the shoe outline shape, and obtain the gradient transition change based on the magnitude relationship between the stresses in the stress functional regions to generate the gradient change region of the shoe outline shape.

[0031] The 3D printing module is used to print the shoe outline with stress functional areas and gradient change areas using Gyroid porous material, based on 3D printing technology, into a shoe with a Gyroid variable gradient porous structure that is suitable for the shape of the foot.

[0032] The present invention discloses the following technical effects:

[0033] This invention combines mathematical calculations with modeling techniques, reducing production costs and shortening the manufacturing cycle.

[0034] This invention proposes a method for applying human foot shape and foot stress measurement to footwear design, thereby expanding the scope of 3D printing customization services.

[0035] This invention employs a porous structure, which can utilize the physical properties of the porous structure itself, such as the high porosity and surface area of ​​the Gyroid structure, as well as its lightweight and certain strength characteristics, to provide more achievable excellent properties for footwear.

[0036] This invention utilizes a parametric modeling method, which allows for the adjustment of relevant data as needed. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is the stress distribution diagram described in this invention;

[0039] Figure 2 This is a schematic diagram of the deformation gradient three-period minimum surface porous structure described in this invention;

[0040] Figure 3 This is a schematic diagram of the 3D deformation-dependent gradient porous structure described in this invention;

[0041] Figure 4 This is the modeling layer construction method described in this invention;

[0042] Figure 5 This is a schematic diagram of the method described in this invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0044] like Figure 1-5 As shown, this invention discloses a method for fabricating a stress-based shoe with a variable gradient porous structure, specifically including the following process:

[0045] By acquiring the stress distribution map of the foot and the ground during walking, boundary division and boundary fitting are performed;

[0046] Based on the boundary division and boundary fitting results, a three-period minimum surface porous structure based on stress distribution and deformation gradient is generated; the entire shoe body is then constructed.

[0047] Based on the above design and fabrication process of shoes with random variable gradient porous structures, the following details the characteristics of the fabrication process:

[0048] The process of obtaining the application distribution map and performing boundary division and boundary fitting in this invention includes the following steps:

[0049] The stress distribution of the sole of the foot is collected by a plantar pressure testing device to obtain stress distribution maps of various parts of the sole during human activity.

[0050] The stress distribution data is exported as a .txt point cloud file, and the point cloud density is analyzed. The initial range boundary is selected based on the "percentage method".

[0051] Fitting method: Perform bivariate nth-order spline fitting on the selected initial range boundary (where n is an integer ≥ 3), and derive the corresponding fitting formulas. The larger n is, the more accurate the fitting, but the greater the computational load.

[0052] Assuming there is only one boundary, the boundary formula obtained by recording the fit is g(x, y, z).

[0053] like Figure 1 As shown in the obtained stress diagram, the minimum stress value is min, and the maximum is max, with a range of (max-min). Now, we introduce the σ factor, which represents:

[0054]

[0055] Here, Y[g(x, y, z)] represents the stress value on the corresponding boundary (isostress line). Clearly, when Y[g(x, y, z)] = max, σ = 0, this value can describe the proximity of the boundary (isostress line) to the stress maximum. Therefore, different boundaries can be selected by adjusting this value. This value is actually adjusted based on experiments or user feedback regarding shoe comfort.

[0056] As shown in Figure 2, region A employs a minimum surface porous structure with low fill rate and large pore size; while region B employs a minimum surface porous structure with high fill rate and small pore size. Regions A and B need to achieve a smooth transition, rather than a simple mechanical mixing / adhesion.

[0057] It can be generated using the following formula:

[0058] Fn(x,y,z)=s(x,y,z)·F1(x,y,z)+(1-s(x,y,z))·F2(x,y,z)

[0059] Fn(x, y, z): The final variable gradient porous structure generated.

[0060] s(x, y, z): Stress boundary, obtained by transforming the function g(x, y, z).

[0061] F1(x, y, z): Spatial expression for a certain minimum surface type porous structure, denoted as A.

[0062] F2(x, y, z): A spatial expression for another type of minimum surface porous structure, distinct from A, denoted as B. It should be noted that B can be the same type of porous structure as A but with different unit cell size or fill rate. Obviously, the case described in this example is this one.

[0063] Plot the above 3D expression in MATLAB software, with the plotting range (or effective region / constraint) set to v(x, y, z). This yields the final 3D deformation-dependent gradient porous structure, as shown below. Figure 3 As shown: Range relationship: Fn=F1∪F2∪s

[0064] Wherein, s(x, y, z) is an adaptation factor used to control the smooth change of gradient transition. During application, this invention needs to be tested and adjusted, and its function is as follows:

[0065]

[0066] exp[] represents the exp function, the g function determines the gradient transition space between the two original structures, and α is the factor that determines the speed of the gradient transition.

[0067] g(x, y, z) is a spatial graph function, if g = x 2 +y 2 +z 2 -r 2

[0068] The two function structures will then form a gradient transition on the surface of a sphere with a spatial radius of r.

[0069] Based on the aforementioned porous structure transition function, which exhibits a gradient change and is referred to as "conformal gradient," this invention is applied to this 3D-printed shoe, with different porosities set at the corresponding boundaries to achieve a support effect:

[0070] Fn(x, y, z) → Total range of shoe body / insole;

[0071] s(x, y, z) → transition region, porous structure with gradient changes;

[0072] F1(x, y, z) → High resilience zone, porous structure with high porosity;

[0073] F2(x, y, z) → hard-supported region, porous structure with low porosity.

[0074] The high porosity is 50-80%, preferably 65%; the low porosity is 20-50%, preferably 45%; and the gradient porosity ranges from 20-80%, preferably 45%-65%.

[0075] Additional notes on Gyroid's porous structure

[0076] (Gyroid, a type of extremely small curved surface with high porosity and surface area, is lightweight yet possesses a certain strength. As a material structure for insoles, it can provide good shock absorption, support, and breathability. With a constant volume, porosity and wall thickness have a zero-to-zero relationship. Therefore, this invention can adjust the porosity or wall thickness to increase or decrease the stress intensity borne by the structure according to the pressure distribution pattern of the foot. To ensure that the shoe and insole structure have the appropriate strength to support pressure, this invention sets the pore size to 200-1000 micrometers, wherein the material with a Gyroid porous structure is generated based on elastic materials such as TPU.)

[0077] This invention, using the Gyroid structure as an example, designs a zoned structure to provide different levels of support based on the user's foot shape and foot stress. These different levels of support are achieved by adjusting the porosity; that is, areas with higher stress have lower porosity, resulting in better support. This insole can be used as an athletic shoe insole and possesses excellent shock absorption and breathability.

[0078] This invention uses the Gyroid structure as an example only; however, this formula for mixing porous structures is applicable to the mixing of all minimal surface-type curved porous structures.

[0079] The Gyroid structure formula is: sinx·cosx + siny·cosz + sinz·cosx = t, where t is a constant that determines the initial position of the Gyroid structure isosurface; x, y, and z are three free variables in the three-dimensional coordinate system.

[0080] The construction process of the entire shoe body proposed in this invention can be simplified to the following steps:

[0081] 1. Scan the shape of the foot and generate a fitting formula for the shoe outline;

[0082] 2. Test foot stress, divide the area according to stress level, and obtain the boundary fitting formula;

[0083] 3. Substitute the shoe outline fitting formula and boundary fitting formula into the multi-structure mixing formula;

[0084] 4. Obtain the final shape of the sole and insole.

[0085] This invention has a wide range of applications, not only in footwear design but also providing technical inspiration for related mechanical design in other fields. In addition, by determining the corresponding data and applying it to calculation formulas, this invention can quickly derive the desired shape or structure using a computer. Furthermore, this invention can break free from the limitations of traditional manufacturing processes, leveraging the greater advantages of 3D printing technology in manufacturing complex structures, thus increasing the space for innovation in footwear design.

[0086] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0087] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0088] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0089] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for fabricating a stress-based shoe with a variable gradient porous structure, characterized in that, Includes the following steps: Scan the shape of the foot to generate the outline of the shoe; The stress distribution on the sole of the foot is collected, and the boundary distribution of the stress on the sole of the foot is obtained through boundary fitting to generate a stress functional zone, wherein the stress functional zone is used to adapt to the stress distribution on the sole of the foot. The stress functional area is fitted to the shoe outline shape, and the gradient transition change is obtained based on the magnitude relationship between the stresses in the stress functional areas to generate the gradient change area of ​​the shoe outline shape. Based on 3D printing technology, the shoe outline with the stress functional area and the gradient change area is printed into a shoe with a Gyroid variable gradient porous structure and suitable for the shape of the foot using Gyroid porous material. The Gyroid porous material is used to represent an elastic material with a Gyroid porous structure. In the process of obtaining the boundary distribution of plantar stress, the stress distribution map at various points on the sole of the foot is obtained, point cloud is extracted, and the initial range boundary of plantar stress distribution is obtained by analyzing the point cloud density. By performing bivariate nth-order spline fitting on the initial range boundary, the boundary distribution of the plantar stress is obtained, where n is an integer greater than or equal to 3; In the process of generating stress functional zones, based on the boundary distribution of plantar stress, by obtaining the maximum stress value, an adjustment factor is obtained to characterize the impact of stress value on comfort. The comfort level of different stress areas is adjusted by the adjustment factor to generate the stress functional zone; In the process of obtaining the regulation factor, the regulation factor is represented as follows: ； Where max represents the maximum stress value, and Y[g(x, y, z)] represents the stress value on the corresponding boundary; In the process of generating stress functional zones, the stress functional zones include: a high resilience zone and a rigid support zone, wherein the high resilience zone is adapted to the minimum stress value, and the rigid support zone is adapted to the maximum stress value; In the process of obtaining the gradient change region, the gradient change region is represented as: F n (x,y,z)=s(x,y,z)·F1(x,y,z)+(1-s(x,y,z))·F2(x,y,z); Where s(x, y, z) is the stress boundary between two stress functional zones, F1(x, y, z) is the spatial expression of one stress functional zone, and F2(x, y, z) represents the spatial expression of another stress functional zone that is different from F1(x, y, z). In the process of obtaining the stress boundary, the stress boundary is used to control the smooth transition of the gradient between two stress functional regions, and is expressed as: ； In the formula, g(x, y, z) represents the spatial graphic function of the stress functional region, and α represents the determinant of the gradient transition rate. Where g = x 2 +y 2 +z 2 -r 2 When this occurs, a gradient transition is formed between the stress functional zones on the surface of a sphere with a spatial radius of r.

2. The method for preparing a stress-based shoe with a variable gradient porous structure according to claim 1, characterized in that: In the process of using Gyroid porous structure material, the pore size of the Gyroid porous structure material is set at 200-1000 micrometers.

3. The method for preparing a stress-based shoe with a variable gradient porous structure according to claim 2, characterized in that: In the process of using Gyroid porous structure material, the pore size of the Gyroid porous structure material is set at 500 micrometers.

4. The method for preparing a stress-based shoe with a variable gradient porous structure according to claim 3, characterized in that: In the process of printing shoes suitable for the foot shape, the high-resilience zone is prepared using a high-porosity Gyroid porous structure material, the rigid support zone is prepared using a low-porosity Gyroid porous structure material, and the gradient zone is prepared using a Gyroid porous structure material with gradient-varying porosity, wherein the high porosity is 65%, the low porosity is 20-50%, and the gradient-varying porosity ranges from 20-80%.

5. The method for preparing a stress-based shoe with a variable gradient porous structure according to claim 4, characterized in that: In the process of printing shoes suitable for the foot shape, the high porosity is 65%; the low porosity is 45%; and the gradient porosity varies from 45% to 65%.

6. A fabrication system for a stress-based shoe with a variable gradient porous structure, characterized in that, A method for fabricating a shoe with a variable gradient porous structure as described in claim 1 includes: The scanning module is used to scan the shape of the foot and generate the outline of the shoe. The stress functional zone division module is used to collect the plantar stress distribution, obtain the boundary distribution of plantar stress through boundary fitting, and generate stress functional zones, wherein the stress functional zones are used to adapt to the plantar stress distribution. The gradient change region segmentation module is used to fit the stress functional region to the shoe outline shape, and obtain the gradient transition change based on the magnitude relationship between the stresses in the stress functional regions to generate the gradient change region of the shoe outline shape. The 3D printing module is used to print the shoe outline with the stress functional area and the gradient change area using Gyroid porous material, based on 3D printing technology, into a shoe with a Gyroid variable gradient porous structure that is suitable for the shape of the foot.

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