Concave honeycomb structure deformation method applied to sole

Abstract

The invention relates to the field of shoes, and discloses a concave honeycomb structure deformation method applied to a sole, which comprises the following steps of: firstly deforming a middle layer, gradually converting a unit body configuration from an initial concave hexagonal configuration into a flat irregular hexagonal configuration, and enabling the structure to be located at a first platform stage of a stress-strain curve at the moment; the hexagonal configuration deforms into that adjacent unit walls of the structure are in mutual contact and are gradually compressed to form double unit walls, and the structure is located at a second platform stage of the stress-strain curve; performing uniaxial quasi-static compression experiments on the classic hexagonal honeycomb structure, the two-dimensional concave honeycomb structure and the three-dimensional concave honeycomb structure by using a universal testing machine; three types of test pieces with different geometrical shapes of honeycomb structures are printed through a selective laser sintering technology. The composite material has the advantages of being excellent in specific stiffness and specific strength and excellent in energy absorption capacity.

Description

Technical Field

[0001] The invention relates to the field of footwear, and in particular to a method for deforming an inner concave honeycomb structure applied to a shoe sole. Background Art

[0002] 3D printing technology, also known as additive manufacturing technology, is in an upward stage of application in the field of footwear at home and abroad. At present, 3D printing technologies include Stereo Lithography Appearance (SLA), Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), etc. Since 2013, 3D printing technology has been widely used in the field of footwear manufacturing. However, it is worth noting that the earliest 3D printing insoles was mainly used in the medical field, especially in the production of medical corrective insoles. Today, research on 3D printed insoles and footwear manufacturing has made significant progress. This research covers a wide range of content, from specific implementation technologies to material selection to potential application scenarios.

[0003] The midsole structure of 3D printed shoes is mainly a lattice structure, and the lattice structure material, as a key part of future multifunctionality, has attracted the attention of scholars at home and abroad. Since the 1950s, various theories on the design and application of porous structure materials have emerged, making people more and more aware of porous structure lattice structure materials. Lattice structure materials can achieve the characteristics that only hollow materials have so far, such as high stiffness, high energy absorption and low-density fracture toughness.

[0004] The concave honeycomb structure is a type of lattice structure. The honeycomb structure is a natural frame structure, in which the two-dimensional units in the plane are arranged in a regular pattern, and the three-dimensional space is arranged in parallel layers, forming a structure with a regular topological layout. The interconnection of the unit cells inside this structure forms a network structure. Compared with the matrix material, the honeycomb structure has a higher porosity and lighter density, so it has superior specific stiffness and specific strength as well as excellent energy absorption capacity. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the deficiencies in the prior art, the present invention provides a method for deforming an inwardly concave honeycomb structure applied to a shoe sole, which has the advantages of superior specific stiffness and specific strength and excellent energy absorption capacity, and solves the problems in the above-mentioned background technology.

[0007] (II) Technical solution

[0008] In order to achieve the above-mentioned superior specific stiffness and specific strength and excellent energy absorption capacity, the present invention provides the following technical solution: a method for deforming an inner concave honeycomb structure applied to a shoe sole, comprising the following steps:

[0009] Step S1: The middle layer deforms first, and the unit cell configuration gradually changes from the initial concave hexagonal configuration to a flat irregular hexagonal configuration. At this time, the structure is in the first platform stage of the stress-strain curve;

[0010] Step S2: The hexagonal configuration is deformed so that the adjacent unit walls of the structure contact each other and are gradually compressed to form double unit walls, and the structure is in the second platform stage of the stress-strain curve;

[0011] Step S3: using a universal testing machine to perform uniaxial quasi-static compression tests on the classic hexagonal honeycomb structure, the two-dimensional concave honeycomb structure, and the three-dimensional concave honeycomb structure;

[0012] Preferably, the concave honeycomb structure in step S3 is determined by three basic parameters, including unit body width w, straight side length s and inclination angle θ, and the other two geometric parameters include unit body height h and hypotenuse length l, which can be expressed by three basic parameters:

[0013] h=2s-2lcosθ

[0014]

[0015] At the same time, in order to ensure the consistency of the honeycomb configuration, the geometric constraints on the unit cell need to satisfy the following inequality (1):

[0016] s ≥ 2lcosθ

[0017] Among them, l represents the length of the hypotenuse of the unit body, l = 3.2mm, s represents the length of the straight side of the unit body, s = 5mm, h represents the height of the unit body, h = 7.8mm, θ represents the angle between the straight side and the hypotenuse of the unit body, θ = 70°, b represents the length of the unit body in the Z direction, b = 19.5mm, and the concave honeycomb structure contains N x *N y =3*3 cells;

[0018] Relative density r is defined as the ratio of the effective density to the density of the matrix material, or the ratio of the volume of the structural member to the volume of the structural envelope. The relative density of the two-dimensional concave honeycomb structure can be expressed as:

[0019]

[0020] The geometric parameters of the unit cell height h and the hypotenuse length l still satisfy the above equations 1 and 2. To ensure the consistency of the structure, the design parameters of the three-dimensional concave honeycomb structure need to satisfy the following geometric coordination constraint inequalities (2, 3):

[0021] s ≥ 2lcosθ

[0022] If the cell wall thickness t is taken into account, the above geometric constraints will change to:

[0023]

[0024] In order to avoid the overlap of adjacent straight edges that share a hypotenuse in the structure, the following inequality (4) must also be satisfied:

[0025] t<lsinθ

[0026] Where I represents the length of the hypotenuse of the unit cell, I = 3.2 mm, s represents the length of the straight side of the unit cell, s = 5 mm, h represents the height of the unit cell, h = 7.8 mm, θ represents the angle between the straight side and the hypotenuse of the unit cell, θ = 70°, and w represents the width of the unit cell, w = 6 mm. The three-dimensional concave honeycomb structure contains N x *N y *N z =3*3*3 cells;

[0027] Considering a parameter, namely the cell wall thickness (t), which ranges from 0.9 mm to 1.5 mm, with an interval of 0.1 mm, the test results show that the size of the specimen in the x direction is 19.5 mm, the size in the y direction is 13.8 mm, and the size in the z direction is 19.5 mm. The relative density ρ of the three-dimensional concave honeycomb structure is r It can be defined as:

[0028]

[0029] Among them, the first term in the numerator is used to calculate the volume of the vertical rod in the unit body, the part s represents the elongated volume caused by the thickness of the vertical rod, and the second term in the numerator is used to calculate the volume of the inclined rod in the unit body, where the part subtracted from l represents the volume of the inclined rod reduced due to the overlap of the vertical rod with the inclined rod;

[0030] The two-dimensional concave honeycomb structure specimen was subjected to an in-plane quasi-static compression test, including the use of an MTS electronic universal testing machine with a maximum test force of 30KN to perform a uniaxial quasi-static compression test in the z direction of the specimen. The testing machine includes an electronic displacement controller, a load sensor, a loading platform and a pressure plate. The specimen was placed between two metal pressure plates;

[0031] Engineering stress-strain curve refers to the stress-strain curve commonly used in practical engineering applications. It is a stress-strain curve obtained by measuring the external load and the deformation of the specimen. The stress value is the load divided by the force-bearing area of ​​the specimen, and the strain value is the deformation of the specimen divided by the initial size in the loading direction. The stress expression is:

[0032]

[0033] Among them, σ is the engineering stress, F is the force loaded during the compression process, and A is the stress area of ​​the specimen;

[0034] The mathematical expression of engineering strain is:

[0035]

[0036] Among them, ∈ is the engineering strain, ΔL is the deformation in the compression direction, and L is the initial size of the specimen;

[0037] In the process of compression of the two-dimensional concave honeycomb structure, stress does work, and the engineering stress-strain curve can be integrated to obtain the strain energy, and its mathematical expression is:

[0038]

[0039] Where σ represents the compressive force, W represents the strain energy, and ε d is the strain value corresponding to the densification of the structure, and the result calculated at this time is the strain energy per unit volume.

[0040] Step S4: Three types of honeycomb structures with different geometric shapes were printed by selective laser sintering technology.

[0041] (III) Beneficial effects

[0042] Compared with the prior art, the present invention provides a method for deforming a concave honeycomb structure applied to a shoe sole, which has the following beneficial effects:

[0043] The present invention uses 3D printing technology to manufacture two different honeycomb structure specimens, focusing on how the geometric dimensions affect the mechanical performance of the structure. The test results reveal that these structures exhibit unique deformation behaviors when subjected to stress, especially the characteristics of a double-platform stress response. Among them, the first stress platform is approximately twice the size of the second stress platform, and this phenomenon enhances the compression resistance of the structure. As the relative density of the structure increases, the structure transitions from the double-platform stage to the single-platform stage. In addition, the performance of two-dimensional and three-dimensional concave honeycomb structures in energy absorption was compared, and it was found that the two-dimensional concave honeycomb structure performed better in this regard, and the three-dimensional concave honeycomb structure performed better in energy absorption efficiency. The relationship between the geometric dimensions of the structure and its equivalent Young's modulus was also established in the study, and this result provides an important theoretical basis for further insole optimization design. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the method of the present invention;

[0045] Figure 2 is a stress-strain curve diagram of the two-dimensional honeycomb structure of the present invention under quasi-static compression;

[0046] Figure 3 This is a diagram showing the deformation process of a specimen in a uniaxial quasi-static compression test in the z direction of the present invention;

[0047] Figure 4 It is a graph showing the energy absorption of the two-dimensional concave honeycomb structure of the present invention;

[0048] Figure 5 It is a curve diagram of energy absorption efficiency of the two-dimensional concave honeycomb structure of the present invention;

[0049] Figure 6 This is a SEA-strain curve diagram of the two-dimensional concave honeycomb structure of the present invention;

[0050] Figure 7 It is a stress-strain curve diagram of the three-dimensional concave honeycomb structure of the present invention under quasi-static compression;

[0051] Figure 8 Comparison of deformation modes of different concave honeycomb structures of the present invention, including: (a) deformation mode of a two-dimensional concave honeycomb structure; (b) deformation mode of a three-dimensional concave honeycomb structure;

[0052] Fig. 9 The comparison of the unit volume strain energy of the two structures of the present invention;

[0053] Fig.10 1 is the equivalent elastic modulus and unit wall thickness curve of the two structures of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] Embodiment 1:

[0056] The present invention provides a technical solution: a method for deforming an inner concave honeycomb structure applied to a shoe sole, comprising the following steps:

[0057] Step S1: The middle layer deforms first, and the unit cell configuration gradually changes from the initial concave hexagonal configuration to a flat irregular hexagonal configuration. At this time, the structure is in the first platform stage of the stress-strain curve;

[0058] Step S2: The hexagonal configuration is deformed so that the adjacent unit walls of the structure contact each other and are gradually compressed to form double unit walls, and the structure is in the second platform stage of the stress-strain curve;

[0059] Step S3: using a universal testing machine to perform uniaxial quasi-static compression tests on the classic hexagonal honeycomb structure, the two-dimensional concave honeycomb structure, and the three-dimensional concave honeycomb structure;

[0060] Step S4: Three types of honeycomb structures with different geometric shapes were printed by selective laser sintering technology.

[0061] According to the Gibson-Ashby classical theory, the platform stages of different models are related to the differences in materials and structures. For elastic porous microstructures, the stress in the platform stage increases rapidly with the increase of strain; all porous microstructures go through three typical stages, namely the elastic strain stage, the platform stage and the densification stage. However, unlike the traditional hexagonal honeycomb structure stress-strain curve which has only one platform stage, the two-dimensional concave honeycomb structure shows obvious double-platform stress stage characteristics in the in-plane direction at a specific unit cell thickness (t≤1.0mm), such as Figure 2 As shown in Figure 2, the stress variation of this type of two-dimensional concave honeycomb structure can be divided into four stages, namely the elastic stage, the first platform stage, the second platform stage and the densification stage. Figure 3 A series of snapshots of the deformation profile corresponding to typical strain levels on the stress-strain curve are given.

[0062] In the elastic stage, the stress is proportional to the strain until it reaches the first peak. The two-dimensional concave honeycomb structure has no obvious macroscopic deformation in this stage, such as Figure 3a)②. When the strain is about 0.1, the cell wall is slightly bent. After exceeding the first peak, as the stress increases, the stress of the structures with cell wall thickness t=0.9mm and t=1.0mm fluctuates roughly around 0.19MPa, which is the first platform stress. In the first platform stress stage, the deformation of the two-dimensional concave honeycomb structure is mainly dominated by the bending and rotation of the cell wall. Once compression occurs in the z direction, the beveled edge will be subjected to external bending moment around the joint with the straight edge. The straight edge will also bend due to bending moment and instability. When the overall strain increases to 0.2, all unit cells gradually deform from the initial concave hexagon to an irregular hexagon tilted in a fixed direction, and the deformation from the concave hexagon to the tilted irregular hexagon occurs layer by layer, as shown in Figure 3 a)③. In addition, the bending and rotation of the unit wall cause the unit body to gather toward the central layer of the specimen, resulting in a typical negative Poisson's ratio effect. Due to the existence of friction, the unit body in contact with the upper and lower platens does not undergo obvious horizontal displacement. When the strain is further squeezed to 0.4, the middle layer is compacted first, and the other two layers gradually undergo more obvious deformation, such as Figure 3 a)④ As shown. After the concave hexagonal structure is deformed into an irregular hexagonal structure, which is the first step of deformation of the specimen, the stress enters the second platform stress stage as the strain increases, as shown in Figure 3 a). There is a relatively obvious boundary between the two platform stages on the stress-strain curves of the two specimens, which are distinguished by the platform strain εp of 0.23. The second platform stress is about 0.36MPa, which is about twice the stress of the first platform, indicating that the deformation of the unit body from a concave hexagon to an irregular hexagon is beneficial to improving the compressive strength of the structure. The two adjacent unit walls of the concave structure contact each other to form an irregular hexagonal double unit wall. This deformation is the second step deformation of the specimen. Because the double unit wall provides more support to the unit body, plastic hinges are formed at the nodes, resulting in a greater stress level than the first platform stage. As the strain increases further, the first layer and the middle layer of the structure are compacted, and the stress increases sharply, as shown in Figure 3 a)⑤. In the densification stage, the unit cell is completely compacted and the concave honeycomb structure shows lateral expansion, which is similar to the traditional hexagonal honeycomb structure, such as Figure 3 a) ⑥. In the concave honeycomb structure, when the relative density or solid phase volume fraction is low, the compressive stress platform is more obvious; when the matrix material is TPU elastic material, as the relative density increases, the stress platform length of the concave honeycomb structure is sharply shortened; when the relative density rises to above 0.5, the double platform stress effect of the concave honeycomb structure disappears and turns into a single platform stress; when the relative density rises to above 0.60, the stress platform gradually disappears, and the compressive deformation of the concave honeycomb material gradually turns into a uniform deformation behavior similar to that of a fully dense material.

[0063] As the strain increases, the energy absorption of the two-dimensional concave honeycomb structure will also increase. As can be seen from the figure, the energy absorption capacity of the structure increases with the increase of the cell wall thickness. Therefore, in the absence of obvious defects in the structure, the greater the relative density, the stronger the energy absorption capacity of the structure. In the elastic stage, the stress increases slowly, and the energy absorption capacity of the structure is weak; the unit volume strain energy increases slightly. After entering the platform stage, the stress fluctuates around a certain value, and the unit volume strain energy increases slowly. With the arrival of the densification stage, the structure is gradually compacted, the stress value rises sharply, and the unit volume strain energy increases rapidly with the increase of strain. According to formula 1, the unit volume strain energy of the two-dimensional concave honeycomb structure with different cell wall thicknesses is shown in Table 1.

[0064] Table 1 Strain energy per unit volume of two-dimensional concave honeycomb structure

[0065]

[0066] Energy absorption efficiency refers to the ratio of the energy absorbed by the lattice structure at a certain strain value during the compression process to the stress value at this strain. The mathematical expression is:

[0067]

[0068] Among them, σ is the compression force, ε is the overall strain of the structure, and η(ε) represents the energy absorption efficiency under a certain strain. The energy absorption efficiency of different structures goes through the stages of linear increase, fluctuation, and decrease. Figure 5 It can be seen that in the early elastic stage, the energy absorption efficiency of the concave honeycomb structure is proportional to the strain, and then the energy absorption efficiency increases sharply. After entering the platform stage, the energy absorption efficiency reaches a peak in the middle of the platform stage. Due to the existence of a double platform stage, the curve of the concave honeycomb structure with a cell wall thickness of 0.9mm and 1.0mm will reach the second peak as the structure enters the second platform stage. The highest energy absorption efficiency is 16.38% and 16.57% respectively. The concave honeycomb structures with a cell wall thickness of 1.1mm and 1.2mm both reach a peak energy absorption efficiency in the middle of the platform stage, and their values ​​are 17.72% and 16.02% respectively. The above results show that the cell wall thickness is not the only determining factor of the energy absorption efficiency. The strength, stiffness and structural stability of the material can all affect the energy absorption efficiency.

[0069] Specific energy absorption (SEA) is usually used to characterize the energy absorption capacity of honeycomb structures. It is obtained by dividing the total absorbed energy of the structure by the total mass of the structure. SEA is determined by integrating the stress-strain curve and is expressed as:

[0070]

[0071] Among them, σ represents the compressive stress, ε represents the strain of the entire structure, ρr represents the mass density of the matrix material, and ρs represents the relative density of the honeycomb structure. The larger the SEA value, the better the energy absorption capacity. The SEA-strain curves of specimens with different cell wall thicknesses are shown in Figure 2. Figure 6 As shown in the figure. Since the stress-strain curve is staged, the SEA curve shows different increasing trends; in the elastic stage, the slope is small and the increasing trend is slow. From the platform stage to the densification strain, the slope is large and the SEA increasing trend gradually increases. After entering the densification stage, the slope reaches the maximum and the SEA value also reaches the peak value.

[0072] In order to study the mechanical properties of the three-dimensional concave honeycomb structure in the quasi-static elastic stage, a universal testing machine was used to carry out uniaxial quasi-static compression tests in the z direction. All tests were carried out at room temperature. The specimen was placed on the fixed floor of the testing machine and a displacement-controlled load was applied at a constant speed of 1.8 mm / min, as shown in Figure 2. Figure 7 As shown. During the test, a camera was used to record the test process at a speed of 2 frames per second. The stress and strain during the flat pressing process were calculated based on the original size of the specimen, and the equivalent elastic modulus of the two-dimensional concave honeycomb structure specimen was obtained by calculating the slope of the stress-strain curve in the elastic stage. To ensure the reliability of the test data, the same specimen was tested three times and the average value was calculated.

[0073] Some three-dimensional concave honeycomb structures are similar to two-dimensional concave honeycomb structures. At a specific unit thickness (t≤1.3mm), the in-plane direction shows obvious double-platform stress characteristics. The stress changes of this type of three-dimensional concave honeycomb structure can be divided into four stages: elastic stage, first platform stage, second platform stage and densification stage. When the unit thickness is greater than 1.3mm, the double-platform stress gradually develops into a single platform stress. There are only three stages of stress changes in this type of honeycomb structure: elastic stage, platform stage and densification stage. Figure 7 Snapshots of typical strain level deformation contours on the stress-strain curves of some structures are given.

[0074] Embodiment 2:

[0075] Comparison of mechanical properties of concave honeycomb structures

[0076] The deformation mode of the concave honeycomb structure in the double platform stage can be divided into two steps. The first step of the two-dimensional concave honeycomb structure is that the middle layer deforms first, and the unit body configuration gradually changes from the initial concave hexagonal configuration to a flat irregular hexagonal configuration. This is the first platform stage. The second step of deformation is that the adjacent unit walls of the structure contact each other and are gradually compressed to form double unit walls. This is the second platform stage. Figure 8(a) shows. The first step of deformation of the three-dimensional concave honeycomb structure is that the unit cell of the middle layer changes from the initial concave hexagonal configuration to a rectangular configuration. At this time, the structure is in the first platform stage of the stress-strain curve. The second step of deformation is that the adjacent unit walls of the structure contact each other to form a double unit wall. At this time, the structure is in the second platform stage of the stress-strain curve, as shown in Figure 8 (b) The deformation mode of the rectangular configuration is conducive to improving the compressive strength of the structure as a whole; while the deformation mode of the double-unit wall is conducive to providing more support for the structure as a whole, further improving the compressive strength of the structure.

[0077] The value of the unit volume strain energy W is calculated. For the two-dimensional concave honeycomb structure, the test results show that its unit volume strain energy is significantly higher than that of the three-dimensional concave honeycomb structure. This is because the relative density of the two-dimensional honeycomb structure is higher than that of the three-dimensional concave honeycomb structure, so it absorbs more energy under the same volume, such as Fig. 9 However, by comparing the energy absorption efficiency of the two, it is found that the absorption efficiency of the three-dimensional concave honeycomb structure is significantly higher than that of the two-dimensional concave honeycomb structure. The specific values ​​are shown in Table 2.

[0078] Table 2 Energy absorption efficiency of two concave honeycomb structures with different cell wall thicknesses

[0079]

[0080] The equivalent elastic modulus is an important parameter for evaluating the stiffness of a structure, and can be obtained by calculating the slope of the equivalent stress-strain curve of the honeycomb structure in the elastic stage. The specific values ​​of the equivalent Young's modulus of the structure under different cell wall thicknesses are shown in Table 3.

[0081] Table 3 Equivalent Young's modulus of two concave honeycomb structures with different cell wall thicknesses

[0082]

[0083] The data in the above table are fitted with a polynomial to obtain the relationship curve between the honeycomb structure unit wall thickness and the equivalent elastic modulus, such as Fig.10 As shown. These curves show different growth trends. When the relative density of the two-dimensional concave honeycomb structure is lower than 0.60, the slope of the curve is relatively small. When the relative density exceeds 0.60, the slope of the curve increases. The three-dimensional concave honeycomb structure shows three different growth trends. When the relative density is lower than 0.45, the slope of the curve is small. When the relative density is between 0.45 and 0.60, the slope of the curve reaches the maximum. When the relative density exceeds 0.60, the slope of the curve becomes smaller. The results show that the relative density of the structure has a significant effect on the growth trend of the equivalent elastic modulus.

[0084] The mapping relationship between the thickness of the cell wall of the concave honeycomb structure and the structural equivalent Young's modulus is established, and the functional relationship between the thickness of the cell wall of the two-dimensional concave honeycomb structure and the structural equivalent Young's modulus is obtained by using a third-order polynomial fitting:

[0085] E 2D =55t 3 -171.3571t 2 +178.1857t-53.6380

[0086] Among them, E 2D is the equivalent Young's modulus of the two-dimensional concave honeycomb structure, t is the cell wall thickness, R 2 The confidence interval reaches 0.99.

[0087] The functional relationship between the thickness of the cell wall of the three-dimensional concave honeycomb structure and the structural equivalent Young's modulus is:

[0088] E 3D =-25.2778t 3 +94.7262t 2 -112.3056t+43.4576

[0089] Among them, E 3D is the equivalent Young's modulus of the three-dimensional concave honeycomb structure, t is the cell wall thickness, R 2 The confidence interval reaches 0.98.

[0090] It should be noted that, in this article, relational terms such as first and second, etc. 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. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0091] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for deforming a concave honeycomb structure applied to a shoe sole, characterized in that: The following steps are involved: Step S1: The middle layer deforms first, and the unit cell configuration gradually changes from the initial concave hexagonal configuration to a flat irregular hexagonal configuration. At this time, the structure is in the first platform stage of the stress-strain curve; Step S2: The hexagonal configuration is deformed so that the adjacent unit walls of the structure contact each other and are gradually compressed to form double unit walls, and the structure is in the second platform stage of the stress-strain curve; Step S3: using a universal testing machine to perform uniaxial quasi-static compression tests on the classic hexagonal honeycomb structure, the two-dimensional concave honeycomb structure, and the three-dimensional concave honeycomb structure; Step S4: Three types of honeycomb structures with different geometric shapes were printed by selective laser sintering technology.

2. The method for deforming the concave honeycomb structure applied to the sole according to claim 1, characterized in that: The concave honeycomb structure in step S3 is determined by three basic parameters, including unit body width w, straight side length s and inclination angle θ. The other two geometric parameters include unit body height h and hypotenuse length l, which can be expressed by three basic parameters: h=2s-2lcosθ At the same time, in order to ensure the consistency of the honeycomb configuration, the geometric constraints on the unit cell need to satisfy the following inequality (1): s ≥ 2lcosθ Among them, l represents the length of the hypotenuse of the unit body, l = 3.2mm, s represents the length of the straight side of the unit body, s = 5mm, h represents the height of the unit body, h = 7.8mm, θ represents the angle between the straight side and the hypotenuse of the unit body, θ = 70°, b represents the length of the unit body in the Z direction, b = 19.5mm, and the concave honeycomb structure contains N x *N y =3*3 cells; Relative density r is defined as the ratio of the effective density to the density of the matrix material, or the ratio of the volume of the structural member to the volume of the structural envelope. The relative density of the two-dimensional concave honeycomb structure can be expressed as: The geometric parameters of the unit cell height h and the hypotenuse length l still satisfy the above equations 1 and 2. To ensure the consistency of the structure, the design parameters of the three-dimensional concave honeycomb structure need to satisfy the following geometric coordination constraint inequalities (2,3): s ≥ 2lcosθ If the cell wall thickness t is taken into account, the above geometric constraints will change to: In order to avoid the overlap of adjacent straight edges that share a hypotenuse in the structure, the following inequality (4) must also be satisfied: t <lsinθ Where l is the length of the hypotenuse of the unit cell, l = 3.2 mm, s is the length of the straight side of the unit cell, s = 5 mm, h is the height of the unit cell, h = 7.8 mm, θ is the angle between the straight side and the hypotenuse of the unit cell, θ = 70°, and w is the width of the unit cell, w = 6 mm. The three-dimensional concave honeycomb structure contains N x *N y *N z =3*3*3 cells; Considering a parameter, namely the cell wall thickness (t), which ranges from 0.9 mm to 1.5 mm, with an interval of 0.1 mm, the test results show that the size of the specimen in the x direction is 19.5 mm, the size in the y direction is 13.8 mm, and the size in the z direction is 19.5 mm. The relative density ρ of the three-dimensional concave honeycomb structure is r It can be defined as: Among them, the first term in the numerator is used to calculate the volume of the vertical rod in the unit body, the part s represents the elongation volume caused by the thickness of the vertical rod, and the second term in the numerator is used to calculate the volume of the inclined rod in the unit body, where the part subtracted from l represents the volume of the inclined rod that is reduced due to the overlap of the vertical rod with the inclined rod.

3. The method for deforming the concave honeycomb structure applied to the sole according to claim 1, characterized in that: The two-dimensional concave honeycomb structure specimen in step S3 is subjected to an in-plane quasi-static compression test, including a uniaxial quasi-static compression test of the specimen in the z direction using an MTS electronic universal testing machine with a maximum test force of 30KN, the testing machine includes an electronic displacement controller, a load sensor, a loading platform and a pressure plate. The specimen is placed between two metal pressure plates; Engineering stress-strain curve refers to the stress-strain curve commonly used in practical engineering applications. It is a stress-strain curve obtained by measuring the external load and the deformation of the specimen. The stress value is the load divided by the force-bearing area of ​​the specimen, and the strain value is the deformation of the specimen divided by the initial size in the loading direction. The stress expression is: Among them, σ is the engineering stress, F is the force loaded during the compression process, and A is the stress area of ​​the specimen; The mathematical expression of engineering strain is: Among them, ∈ is the engineering strain, ΔL is the deformation in the compression direction, and L is the initial size of the specimen.

4. The method for deforming the concave honeycomb structure applied to the sole according to claim 1, characterized in that: In the step S3, during the compression process of the two-dimensional concave honeycomb structure, the stress does work, and the engineering stress-strain curve can be integrated to obtain the strain energy, and its mathematical expression is: Among them, represents the compressive force, W represents the strain energy, and is the strain value corresponding to the densification of the structure. The result calculated at this time is the strain energy per unit volume.

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