Lattice structure rod diameter reverse design method

Abstract

The present application relates to the field of shoe sole design, and specifically relates to a lattice structure rod diameter reverse design method, comprising the following sequentially executed steps: S1: constructing a unit cell structure; S2: defining parameters: connecting rod diameter d1, main rod diameter d2, fiber rod diameter d3, unit cell structure side length L and shape coefficient alpha; S3: generating a test structure; S4: obtaining the super-elasticity data and viscoelasticity data of the test structure, and establishing a finite element analysis model of the test structure; S5: setting each parameter, simulating and analyzing the test structure under each combination, obtaining the mechanical performance indicators of each test structure, and constructing a mechanical performance indicator database using the obtained mechanical performance indicators; S6: determining a unique rod diameter combination; S7: generating a lattice structure for filling a shoe sole according to the obtained rod diameter combination; the design method can quickly realize the reverse design of the rod diameter parameters in the lattice lattice structure, quickly iteratively obtain the rod diameter combination parameters under the target mechanical performance, and save design costs.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of shoe sole design, and particularly relates to a lattice structure rod diameter reverse design method. BACKGROUND

[0002] The lattice point array structure is widely used in the fields of aerospace, sports, biological medicine and the like due to its light weight, high strength and adjustable mechanical properties. At present, most of the lattice designs are designed in a forward direction, and the structural design inspiration is mostly derived from bionic structures or AI algorithms, and the focus is on forward design according to the target performance requirements, and the final mechanical properties are verified after the design is completed.

[0003] The lattice structure design of the shoe sole mainly depends on the adjustment of the structural parameters, but the influence of each parameter on the mechanical response is not clear, and the structure is often adjusted several times depending on experience to meet the performance requirements, and the design process is blind and low in efficiency. SUMMARY

[0004] The purpose of the present application is to provide a lattice structure rod diameter reverse design method for improving the design efficiency of the shoe sole.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A lattice structure rod diameter reverse design method, a unit cell structure is constructed to generate a lattice structure for filling a shoe sole, and the specific construction steps of the unit cell structure are as follows:

[0007] S1: The unit cell structure includes a connecting rod arranged obliquely and a quadrilateral symmetrically arranged on both sides of the connecting rod, the quadrilateral includes two main rods and two auxiliary rods, the two auxiliary rods are connected and connected to the connecting rod, one end of the two main rods is connected to one end of the two auxiliary rods away from the connecting rod, respectively, one by one, and the two main rods away from the two auxiliary rods are connected, forming a first structure;

[0008] A cubic space is constructed, and the distance between one end of the connecting rod and the end of the adjacent main rod away from the connecting rod is taken as the edge length of the cubic space;

[0009] Three first structures are arranged equidistantly along the X-axis direction, and a fiber rod is used to connect three points with the same X-axis and Y-axis coordinates, respectively, to form the unit cell structure;

[0010] S2: Define parameters: connecting rod diameter d1, main rod diameter d2, fiber rod diameter d3, unit cell structure edge length L and shape coefficient a, the shape coefficient a is the ratio of the distance between the connecting point of the main rod and the auxiliary rod and the surface of the nearest cubic space to the unit cell structure edge length L;

[0011] S3: based on the unit cell structure, arrange along the Y axis direction to get a test structure with a single package structure number of 3*3*3;

[0012] S4: obtain the super-elastic data and viscoelastic data of the test structure, and establish a finite element analysis model of the test structure;

[0013] S5: set a plurality of connecting rod diameters d1, set the main rod diameter d2 equal to the fiber rod diameter d3, and set the unit cell side length, simulate and analyze the test structure under each combination, obtain the mechanical performance index of each test structure, the mechanical performance index includes elastic modulus, platform stress, stiffness change modulus and yield stress, and the obtained mechanical performance index is used to construct a mechanical performance index database;

[0014] S6: using machine learning method, based on square exponential kernel function Gaussian process regression, the corresponding proxy model is fitted out in Matlab, and according to the proxy model, any two groups of mechanical performance indexes in the mechanical performance index database can be reversely determined to obtain a unique rod diameter combination;

[0015] S7: generating a dot matrix structure for filling the sole according to the obtained rod diameter combination.

[0016] Preferably, in step S4, the super-elastic data is fitted with Marlow model to sample data, and the viscoelastic data is fitted with Prony series.

[0017] Preferably, in step S4, the accuracy of the calculation model is checked by standard static compression experiment.

[0018] Preferably, in step S3, the shape factor α of the test structure is set to 0.1.

[0019] Preferably, in step S5, the connecting rod diameters d1 are set to 0.9mm, 1.2mm, 1.5mm or 1.8mm, and the unit cell structure side length L is set to 10mm.

[0020] By using the foregoing design scheme, the application has the advantages that the unit cell structure can produce stable multi-stage mechanical response by using elastomer material, and is suitable for engineering scenes such as sports regulation and redundancy protection; the method can quickly realize the reverse design of rod diameter parameters in dot matrix lattice structure, can quickly iterate to obtain rod diameter combination parameters under target mechanical performance, and can save design cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart of the design method of the application;

[0022] Figure 2 The multi-angle schematic diagram of the unit cell structure of the application;

[0023] Figure 3 A structural diagram of a test structure of the application;

[0024] Figure 4 A schematic diagram of a quasi-static compression process of a simulation test structure of the application;

[0025] Figure 5 A schematic diagram of a standard static compression experiment of the application;

[0026] Figure 6 A schematic diagram of a surrogate model fitted in Matlab of the application. DETAILED DESCRIPTION

[0027] In order to make the objects, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0028] The terms "first", "second", "third", and the like in the specification and claims of the application and the above-described drawings are used to distinguish different objects, rather than to describe a particular order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0029] A lattice structure rod diameter reverse design method, as shown in Figure 1 The local strengthening mechanism of bamboo fiber bundles in nature and the staggered arrangement characteristics of the shell pearl layer are used as inspiration to design the unit cell structure, and the basic configuration of the unit cell structure is as shown in Figure 2 The unit cell structure is used to generate a lattice structure for filling the shoe sole, and the specific construction steps of the unit cell structure are as follows:

[0030] S1: The unit cell structure includes a connection rod arranged obliquely and a quadrilateral symmetrically arranged on both sides of the connection rod, the quadrilateral includes two main rods and two auxiliary rods, the two auxiliary rods are connected and connected to the connection rod, one end of the two main rods is connected to the end of the two auxiliary rods away from the connection rod one by one, and the ends of the two main rods away from the two auxiliary rods are connected, forming a first structure.

[0031] Construct a cubic space with the distance between one end of the connecting rod and the end of the adjacent main rod away from the connecting rod as the edge length;

[0032] Arrange the three first structures equidistantly along the X-axis direction, connect each of the three points with the same X-axis coordinate and Y-axis coordinate by a fiber rod to form a unit cell structure;

[0033] S2: define parameters: connecting rod diameter d1, main rod diameter d2, fiber rod diameter d3, unit cell structure edge length L, and shape factor a, which is the ratio of the distance between the connecting point of the main rod and the auxiliary rod and the surface of the nearest cubic space to the unit cell structure edge length L;

[0034] S3: based on the unit cell structure, the shape factor a is set to 0.1, and the test structure with a number of 3x3x3 is obtained by arranging along the Y-axis direction, and the inclination directions of each layer in the test structure are the same, as shown in Figure 3 ;

[0035] S4: obtain the super-elasticity data and viscoelasticity data of the test structure, and establish a finite element analysis model of the test structure;

[0036] In this embodiment, based on the 3D printing TPU material data obtained by experiment, a finite element analysis model is established. As shown in Figure 4 and Figure 5 , the grid model is placed between two rigid plates, all degrees of freedom of the bottom plate and the top plate are constrained except the displacement degree of freedom of the top rigid plate in the Z direction, and the top plate moves downward at a constant speed of 200mm / s to simulate the quasi-static compression process. In order to accurately simulate the super-elasticity and viscoelasticity behavior of TPU material, the super-elasticity and viscoelasticity data in the material constitutive are enabled. The super-elasticity data is fitted with Marlow model for tensile specimen data, and the viscoelasticity data is fitted with Prony series. By standard static compression experiment, the accuracy of the calculation model is checked.

[0037] S5: set multiple connecting rod diameters d1, set the main rod diameter d2 equal to the fiber rod diameter d3, and set the unit cell edge length, in this embodiment, for the lattice crystal structure with "stepped" mechanical behavior, the connecting rod diameters d1 are set to 0.9mm, 1.2mm, 1.5mm or 1.8mm, the main rod diameters d2 are set to 0.9mm, 1.2mm, 1.5mm or 1.8mm, and the unit cell structure edge length L is set to 10mm; simulate and analyze the test structure under each combination, a total of 16 combinations, each combination is simulated once, and the mechanical performance indicators of each test structure are obtained, including elastic modulus, platform stress, stiffness change modulus and yield stress, and the obtained mechanical performance indicators are used to construct a mechanical performance indicator database;

[0038] S6: Adopting machine learning method, based on square exponential kernel function Gaussian process regression, corresponding surrogate model is fitted in Matlab, as shown in Figure 6 According to the surrogate model, any two groups of mechanical performance indexes in the mechanical performance index database can be reversely determined to a unique rod diameter combination. In this embodiment, any two mechanical performance indexes are given, and Matlab program is used for fitting. If there is a solution, the values of rod diameter combination d1 and d2 will be output, otherwise there is no solution.

[0039] S7: Generating dot matrix structure for filling the sole according to the obtained rod diameter combination.

[0040] In order to better illustrate the dot matrix structure rod diameter reverse design method, this embodiment is further illustrated by the following embodiment.

[0041] Taking the elastic modulus and the modulus of stiffness change as examples, the targets are set as 1000 kPa and 3000 kPa respectively, then there may be multiple groups of d1 and d2 combinations that meet the elastic modulus of 1000 kPa, and there may also be multiple groups of d1 and d2 combinations that meet the modulus of stiffness change of 3000 kPa. The Matlab program will search the rod diameter combination that meets the condition based on the fitting data of Figure 6 , and output, otherwise there will be no solution. The detailed solving process is searched by the “Gaussian regression process” program in Matlab, and the Matlab program used in this application does not set specific parameters, but uses default or conventional parameters. By setting the targets of elastic modulus 1000 kPa and modulus of stiffness change 3000 kPa to search and solve, it is found that there is only one real solution that meets the actual condition, i.e. the main rod diameter is 1.6185 mm and the connecting rod diameter is 1.2821 mm.

[0042] In the simulation model, the rod diameters are set as 1.6185 mm and 1.2821 mm respectively, and the simulation results are shown in Table 1. The compression modulus of the elastic section is 1020.8 kPa, and the modulus of the stiffness change section is 2883.6 kPa. The simulation and surrogate model errors are +2.08% and -3.88% respectively. Given the rod diameter coefficient, the fitting values of the first platform stress and yield stress obtained by the mechanical performance surrogate model are 158.8 kPa and 560.1 kPa respectively, while the simulation results are 156.1 kPa and 521.9 kPa respectively, and the simulation errors are -1.70% and -6.82% respectively.

[0043]

[0044] Through the error analysis of the surrogate model and the reverse design simulation, it can be known that the surrogate model as an empirical fitting can accurately guide the reverse design.

[0045] The compression mechanical properties of the lattice structure under the proposed shape coefficient 0.1 are fitted by a Gaussian process regression surrogate model, and the reverse design of the rod diameter is realized. The surrogate model is relatively accurate, and the error of the mechanical indicators obtained by the finite element analysis is small. Among these mechanical indicators, the stiffness change modulus is most affected by the main rod diameter, and has little relationship with the connecting rod diameter. The first platform stress is affected by the interaction of the two rod diameters, and the yield stress is greatly affected by the main rod diameter.

[0046] In summary, the unit cell structure constructed in the present application can utilize the elastomer material to produce stable multi-stage mechanical response, and is suitable for engineering scenarios such as motion adjustment, redundancy protection, etc.

[0047] The present application establishes a mechanical property index database based on the finite element model and experimental test results, and fits a surrogate model, which has high model accuracy and good fitting effect.

[0048] The lattice structure rod diameter reverse design method can quickly realize the reverse design of the rod diameter parameters in the lattice structure, and can quickly iterate to obtain the rod diameter combination parameters under the target mechanical properties, saving design cost.

[0049] The specific embodiments described above further illustrate the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A lattice structure rod diameter reverse design method, characterized in that: A unit cell structure is constructed to generate a lattice structure for filling a shoe sole, and the specific construction steps of the unit cell structure are as follows: S1: The unit cell structure includes a connecting rod arranged obliquely and a quadrilateral symmetrically arranged on both sides of the connecting rod, the quadrilateral includes two main rods and two auxiliary rods, the two auxiliary rods are connected and connected to the connecting rod, one end of the two main rods is connected to the end of the two auxiliary rods away from the connecting rod, respectively, and the other end of the two main rods away from the two auxiliary rods is connected to form a first structure; A cubic space is constructed, and the distance between one end of the connecting rod and the end of the adjacent main rod away from the connecting rod is taken as the edge length of the cubic space; Three first structures are arranged equidistantly along the X-axis direction, and fiber rods are used to connect three points with the same X-axis and Y-axis coordinates, respectively, to form the unit cell structure; S2: Define parameters: connecting rod diameter d1, main rod diameter d2, fiber rod diameter d3, unit cell structure edge length L, and shape factor α, which is the ratio of the distance between the connecting point of the main rod and the auxiliary rod and the surface of the nearest cubic space to the unit cell structure edge length L; S3: Based on the unit cell structure, a test structure with a single package structure number of 3*3*3 is arranged along the Y-axis direction; S4: Obtain the hyperelasticity data and viscoelasticity data of the test structure, and establish a finite element analysis model of the test structure; S5: Set multiple connecting rod diameters d1, set the main rod diameter d2 equal to the fiber rod diameter d3, and set the unit cell edge length, simulate and analyze the test structure under each combination, obtain the mechanical performance indicators of each test structure, including elastic modulus, platform stress, stiffness change modulus and yield stress, and use the obtained mechanical performance indicators to construct a mechanical performance indicator database; S6: Using a machine learning method, a corresponding surrogate model is fitted in Matlab based on a square exponential kernel function Gaussian process regression, and according to the surrogate model, any two groups of mechanical performance indicators in the mechanical performance indicator database can be uniquely determined by the rod diameter combination; S7: Generate a lattice structure for filling a shoe sole according to the obtained rod diameter combination.

2. The lattice structure strut diameter inverse design method of claim 1, wherein: In step S4, the hyperelasticity data is fitted with Marlow model to simulate tensile specimen data, and the viscoelasticity data is fitted with Prony series.

3. The lattice structure strut diameter inverse design method of claim 2, wherein: In step S4, the accuracy of the calculation model is checked by a standard static compression experiment.

4. The method of claim 1, wherein the method further comprises: determining a plurality of lattices; and selecting a lattice from the plurality of lattices. In step S3, the shape factor α of the test structure is set to 0.

1.

5. The lattice structure strut diameter inverse design method of claim 4, wherein: In step S5, the connecting rod diameter d1 is set to 0.9mm, 1.2mm, 1.5mm or 1.8mm, and the unit cell structure edge length L is set to 10mm.

Images