A poisson ratio each direction controllable three-dimensional honeycomb structure and design method

Abstract

A three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio and its design method are disclosed, relating to the field of honeycomb structure technology. The structure includes several honeycomb cells, which are arranged alternately along the X and Y directions to form cell groups. These cell groups are then arrayed and connected along the Z direction to form a three-dimensional honeycomb. Each honeycomb cell comprises two horizontal outer ribs, four oblique outer ribs, four oblique inner ribs, a first horizontal inner rib, and a second horizontal inner rib. The horizontal outer ribs and oblique outer ribs form a hexagonal outer contour. One end of the first horizontal inner rib is connected to the left vertex of the hexagon, and the other end extends inward, connecting to two oblique inner ribs. The other ends of the oblique inner ribs are connected to the upper left and lower left vertices of the hexagon, respectively. One end of the second horizontal inner rib is connected to the right vertex of the hexagon, and the other end extends inward, connecting to two more oblique inner ribs. The other ends of the oblique inner ribs are connected to the upper right and lower right vertices of the hexagon, respectively.

Description

Technical Field

[0001] This invention relates to the field of cellular structure technology, and in particular to a three-dimensional cellular structure with an isotropically adjustable Poisson's ratio and its design method. Background Technology

[0002] Porous honeycomb structures, with their stable stress plateau under compressive loads and efficient energy absorption characteristics, have been widely used in transportation fields such as vehicles, trains, and ships. Traditional two-dimensional honeycomb structures often exhibit a positive Poisson's ratio characteristic under compression, tending to expand laterally outwards, leading to a decrease in the density at the center of the deformation zone and a decline in resistance to indentation. In contrast, specially designed negative Poisson's ratio structures possess an anomalous "tensile expansion effect," exhibiting superior fracture toughness, resistance to indentation, and energy absorption potential.

[0003] Existing two-dimensional cellular structures are mainly limited to in-plane topological layouts in their configuration design, such as Figure 2 As shown, the adjustable range of its structural morphology and geometric parameters is relatively limited, making it difficult to achieve multi-directional performance optimization in three-dimensional space. Furthermore, traditional two-dimensional honeycomb structures typically exhibit specific mechanical response characteristics only in a single in-plane or out-of-plane dimension, lacking the ability to independently control key mechanical parameters such as Poisson's ratio in different directions, thus failing to meet the diverse requirements for anisotropic mechanical behavior under complex load-bearing conditions. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a three-dimensional honeycomb structure with an isotropic adjustable Poisson's ratio and a design method thereof.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A three-dimensional honeycomb structure with an isotropic adjustable Poisson's ratio includes a plurality of honeycomb cells, wherein multiple cells are arranged alternately along the X and Y directions to form cell groups, and the cell groups are arranged in an array and connected along the Z direction to form a three-dimensional honeycomb.

[0007] The cell includes two horizontal outer ribs, four oblique outer ribs, four oblique inner ribs, a first horizontal inner rib and a second horizontal inner rib. The two horizontal outer ribs and the four oblique outer ribs form a hexagon as the outer outline of the cell.

[0008] The first horizontal inner rib has its first end connected to the left vertex of the hexagon of the honeycomb cell, and its second end extends inward. The first ends of the two oblique inner ribs are connected to the second ends of the first horizontal inner rib, and the second ends of the two oblique inner ribs are respectively connected to the upper left vertex and the lower left vertex of the hexagon of the honeycomb cell. The second horizontal inner rib has its first end connected to the right vertex of the hexagon of the honeycomb cell, and its second end extends inward. The first ends of the two oblique inner ribs are connected to the second ends of the second horizontal inner rib, and the second ends of the two oblique inner ribs are respectively connected to the upper right vertex and the lower right vertex of the hexagon of the honeycomb cell.

[0009] Specifically, by adjusting the thickness of the inner and outer oblique ribs, the honeycomb structure can generate a positive Poisson's ratio effect or a negative Poisson's ratio effect when subjected to pressure.

[0010] Furthermore, the X, Y, and Z directions are perpendicular to each other, wherein the X and Z directions form a first plane, and the Y and Z directions form a second plane.

[0011] Furthermore, in the honeycomb cells facing the first plane, the thickness of the oblique outer rib is greater than the thickness of the oblique inner rib, causing the honeycomb cells in the first plane to generate a positive Poisson's ratio effect when compressed; in the honeycomb cells facing the second plane, the thickness of the oblique outer rib is less than the thickness of the oblique inner rib, causing the honeycomb cells in the second plane to generate a negative Poisson's ratio effect when compressed.

[0012] Furthermore, in the honeycomb cells facing the first plane, the thickness of the oblique outer rib is greater than the thickness of the oblique inner rib, causing the honeycomb cells in the first plane to generate a positive Poisson's ratio effect when compressed; in the honeycomb cells facing the second plane, the thickness of the oblique outer rib is greater than the thickness of the oblique inner rib, causing the cell group in the second plane to generate a positive Poisson's ratio effect when compressed.

[0013] Furthermore, in the cell facing the first plane, the thickness of the oblique outer rib is less than the thickness of the oblique inner rib, causing the cell in the first plane to generate a negative Poisson's ratio effect when compressed; in the cell facing the second plane, the thickness of the oblique outer rib is less than the thickness of the oblique inner rib, causing the cell in the second plane to generate a negative Poisson's ratio effect when compressed.

[0014] Furthermore, in the cell of the three-dimensional honeycomb, a reinforcing plate is provided at the position of the horizontal inner rib near the boundary.

[0015] Furthermore, the Poisson's ratio of the honeycomb structure ranges from -0.2 to 0.2.

[0016] A design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio, based on an energy-absorbing enhanced honeycomb structure with an adjustable positive and negative Poisson's ratio, includes the following steps:

[0017] Step S1: Combine the horizontal outer ribs, oblique outer ribs, oblique inner ribs, first horizontal inner ribs and second horizontal inner ribs to form a honeycomb cell, and array the honeycomb cells to form the two-dimensional honeycomb plate;

[0018] Step S2: Arrange the two two-dimensional honeycomb panels orthogonally along the first and second directions respectively, and extract the spatially overlapping area of ​​the two through Boolean operations, thereby transforming the geometric and mechanical properties of the two-dimensional honeycomb into a three-dimensional honeycomb structure.

[0019] Furthermore, it also includes step S3: an additional triangular reinforcing plate is constructed at the boundary of the novel three-dimensional honeycomb structure formed by Boolean operations.

[0020] Furthermore, it also includes step S4: arraying the three-dimensional honeycomb structure as a primitive to generate a periodic three-dimensional honeycomb structure.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention proposes a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio. By combining horizontal outer ribs and oblique outer ribs with internal oblique inner ribs and horizontal inner ribs to form a composite topological configuration, the internal and external ribs of the honeycomb cell deform collaboratively under pressure. By independently adjusting the thickness ratio of the oblique inner and oblique outer ribs, the sign of the Poisson's ratio can be flexibly switched without changing the overall shape. This allows the structure to exhibit differentiated responses of lateral contraction or lateral expansion under different loading conditions, significantly expanding the design space for controlling the mechanical behavior of honeycomb structures.

[0023] 2. This invention proposes a design method for a three-dimensional honeycomb structure with anisotropic Poisson's ratio. By fusing hexagonal positive Poisson's ratio units with concave negative Poisson's ratio units and utilizing the thickness difference between the inner and outer ribs as a control variable, it breaks through the limitation of the traditional structure's limited Poisson's ratio adjustment range. Combined with a cross-shaped Boolean operation design strategy, the structure can exhibit positive or negative Poisson's ratio characteristics (i.e., sign anisotropy) in different axes according to actual engineering requirements, achieving precise matching of multi-scale mechanical properties and greatly improving the design flexibility of the structure under varying working conditions.

[0024] 3. This invention proposes a design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio. Triangular reinforcing plates are constructed at the boundaries of the three-dimensional honeycomb structure formed through Boolean operations. These triangular reinforcing plates significantly alleviate stress concentration at the intersection edges, optimize the instability mode of the structure under compressive loads, and prevent premature collapse or distortion of the honeycomb cells. Combined with the tensile expansion effect brought about by a negative Poisson's ratio, the structure's anti-dent performance is further enhanced, giving it significant technical advantages in the field of impact protection.

[0025] 4. This invention proposes a design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio. Utilizing Boolean operations to extract overlapping regions between two orthogonal two-dimensional honeycombs, this method can completely and efficiently map the superior mechanical characteristics of two-dimensional honeycombs (such as high specific strength and high specific energy absorption) to three-dimensional space. This method not only effectively reduces the overall porosity of the structure, achieving excellent lightweighting, but also overcomes the problems of complex design and difficult mechanical performance prediction in traditional three-dimensional honeycomb structures. This design method provides an efficient solution for the engineering field to bridge the gap between two-dimensional topology and three-dimensional space, possessing significant value for engineering application and promotion. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio according to the present invention.

[0028] Figure 2 This is a schematic diagram of a two-dimensional honeycomb structure;

[0029] Figure 3 This is a comparison curve of the nominal stress-strain of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio and a two-dimensional honeycomb structure according to the present invention.

[0030] Figure 4 This is a schematic diagram of the first plane of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio according to the present invention;

[0031] Figure 5 This is a schematic diagram of the second plane of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio according to the present invention;

[0032] Figure 6 This is a schematic diagram of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio (HS-NP type) according to the present invention.

[0033] Figure 7 This is a Poisson's ratio-strain diagram (HS-NP type) of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio according to the present invention.

[0034] Figure 8 This is a schematic diagram of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio (HS-PP type) according to the present invention.

[0035] Figure 9 This is a Poisson's ratio-strain diagram (HS-PP type) of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio according to the present invention.

[0036] Figure 10 This is a schematic diagram of a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio (HS-NN type) according to the present invention.

[0037] Figure 11 This is a Poisson ratio-strain diagram (HS-NN type) of a three-dimensional honeycomb structure with an isotropically adjustable Poisson ratio according to the present invention.

[0038] In the diagram, 10 is the oblique outer rib; 201 is the first horizontal inner rib; 202 is the second horizontal inner rib; 30 is the horizontal outer rib; 40 is the oblique inner rib; and 50 is the reinforcing plate. Detailed Implementation

[0039] The following is combined Figures 1-11 The present invention will be described in detail below.

[0040] A three-dimensional honeycomb structure with an isotropically tunable Poisson's ratio, such as Figures 1 to 2 As shown, it includes several cell units, and multiple cell units are arranged alternately along the X and Y directions to form cell groups. The cell groups are arranged in an array along the Z direction to form a three-dimensional cell.

[0041] The cell includes two horizontal outer ribs 30, four oblique outer ribs 10, four oblique inner ribs 40, a first horizontal inner rib 201 and a second horizontal inner rib 202. The two horizontal outer ribs 30 and the four oblique outer ribs 10 form a hexagon as the outer outline of the cell.

[0042] The first horizontal inner rib 201 has its first end connected to the left vertex of the hexagon of the honeycomb cell, and its second end extends inward. The first ends of the two oblique inner ribs 40 are connected to the second ends of the first horizontal inner rib 201, and the second ends of the two oblique inner ribs 40 are respectively connected to the upper left vertex and the lower left vertex of the hexagon of the honeycomb cell. The first end of the second horizontal inner rib 202 is connected to the right vertex of the hexagon of the honeycomb cell, and its second end extends inward. The first ends of the two oblique inner ribs 40 are connected to the second ends of the second horizontal inner rib 202, and the second ends of the two oblique inner ribs 40 are respectively connected to the upper right vertex and the lower right vertex of the hexagon of the honeycomb cell.

[0043] Specifically, by setting the thickness of the inner oblique rib 40 and the outer oblique rib 10, the honeycomb structure can generate a positive Poisson's ratio effect when under pressure, or it can generate a negative Poisson's ratio effect when under pressure.

[0044] Specifically, in the three-dimensional honeycomb structure, honeycomb cells are arranged alternately along the X and Y directions to form cell groups, which are further arrayed along the Z direction to form the overall three-dimensional honeycomb configuration. The outer contour of each honeycomb cell is enclosed by two horizontal outer ribs 30 and four oblique outer ribs 10 to form a hexagonal structure. The first horizontal inner rib 201 extends horizontally inward from the left vertex of the hexagon, and the second horizontal inner rib 202 extends horizontally inward from the right vertex of the hexagon. Two pairs of oblique inner ribs 40 converge at the inner ends of the two horizontal inner ribs 20 and extend outward to connect to the adjacent vertices of the hexagon, forming an internal support network. By adjusting the relative thickness ratio of the oblique inner ribs 40 and the oblique outer ribs 10, the honeycomb structure can exhibit a positive or negative Poisson's ratio effect in a specific plane when subjected to compressive load, thus achieving on-demand control of the Poisson's ratio sign.

[0045] like Figure 3 As shown, under quasi-static load, the new three-dimensional honeycomb structure significantly improves the energy absorption per unit mass compared to the two-dimensional honeycomb structure. This indicates that the Boolean operation fusion strategy effectively reduces the porosity of the structure. While ensuring the lightweight advantage of the material, it greatly improves the specific strength and load-bearing capacity of the structure. Therefore, the three-dimensional honeycomb is more suitable for high load-bearing and high impact-resistant buffering scenarios, while the two-dimensional structure is only suitable for low load and general buffering needs.

[0046] Furthermore, the X, Y, and Z directions are perpendicular to each other, wherein the X and Z directions form a first plane, and the Y and Z directions form a second plane. For example... Figure 1 As shown, the first plane is the XZ plane, and the second plane is the YZ plane.

[0047] In the described three-dimensional honeycomb structure, the X, Y, and Z directions form a three-dimensional orthogonal coordinate system, where the XZ and YZ planes correspond to the two main load-bearing planes of the honeycomb structure, respectively. The honeycomb cells located in the XZ plane and those located in the YZ plane can have different thickness relationships between the inner oblique ribs 40 and the outer oblique ribs 10, allowing the same three-dimensional honeycomb structure to exhibit different Poisson's ratio response characteristics when compressed in different planes, thereby meeting the anisotropic mechanical performance requirements under multi-directional load conditions.

[0048] in, Indicates a horizontal outer rib of 30; 1 represents the angle between the horizontal inner rib 20 and the oblique outer rib 10; 2 represents the angle between the horizontal inner rib 20 and the oblique inner rib 40; Indicates the length of the outer diagonal rib 10; This indicates the length of the inner diagonal rib 40.

[0049] In the XZ plane, Indicates a horizontal outer rib of 30; Z1 This indicates the angle between the horizontal inner rib 20 and the oblique outer rib 10; Z2 This indicates the angle between the horizontal inner rib 20 and the oblique inner rib 40; Indicates the length of the outer diagonal rib 10; This indicates the length of the inner diagonal rib 40.

[0050] In the YZ plane, Indicates a horizontal outer rib of 30; X1 This indicates the angle between the horizontal inner rib 20 and the oblique outer rib 10; X2 This indicates the angle between the horizontal inner rib 20 and the oblique inner rib 40; Indicates the length of the outer diagonal rib 10; This indicates the length of the inner diagonal rib 40.

[0051] In this embodiment, as Figures 6 to 7 As shown, in the honeycomb cells facing the first plane, the thickness of the outer oblique rib 10 is greater than the thickness of the inner oblique rib 40, causing the honeycomb cells in the first plane to produce a positive Poisson's ratio effect when compressed; in the honeycomb cells facing the second plane, the thickness of the outer oblique rib 10 is less than the thickness of the inner oblique rib 40, causing the honeycomb cells in the second plane to produce a negative Poisson's ratio effect when compressed. The above three-dimensional honeycomb structure is of the HS-NP type (Honeycomb Structure - Negative and Positive).

[0052] In the XZ plane, It is 11.25mm; Z1 It is 60°; Z2 It is 60°; It is 7.5mm; It is 7.5mm; t z1 It is 0.9mm; t z2 It is 0.3mm.

[0053] In the YZ plane, It is 11.25mm; X1 It is 60°; X2 It is 60°; It is 7.5mm; It is 7.5mm; t x1 It is 0.3mm; t x2 It is 0.9mm.

[0054] In the three-dimensional honeycomb structure, the thickness of the outer oblique ribs 10 in the honeycomb cells facing the XZ plane is greater than the thickness of the inner oblique ribs 40. This causes the inner oblique ribs 40 to preferentially bend and deform under pressure in this plane, driving the honeycomb cells to expand outwards, exhibiting a positive Poisson's ratio effect. Conversely, the thickness of the outer oblique ribs 10 in the honeycomb cells facing the YZ plane is less than the thickness of the inner oblique ribs 40. This causes the outer oblique ribs 10 to dominate the deformation under pressure in this plane, causing the honeycomb cells to contract inwards, exhibiting a negative Poisson's ratio effect. Through this configuration, the three-dimensional honeycomb structure achieves independent control of the negative and positive Poisson's ratios in two mutually perpendicular planes.

[0055] In this embodiment, as Figures 8 to 9 As shown, in the honeycomb cells facing the first plane, the thickness of the outer oblique rib 10 is greater than the thickness of the inner oblique rib 40, causing the honeycomb cells in the first plane to produce a positive Poisson's ratio effect when compressed; in the honeycomb cells facing the second plane, the thickness of the outer oblique rib 10 is greater than the thickness of the inner oblique rib 40, causing the cell group in the second plane to produce a positive Poisson's ratio effect when compressed. The above three-dimensional honeycomb structure is of the HS-PP type (Honeycomb Structure-Positive and Positive).

[0056] In the XZ plane, It is 11.25mm; Z1 It is 60°; Z2 It is 60°; It is 7.5mm; It is 7.5mm; t z1 It is 0.9mm; t z2 It is 0.3mm.

[0057] In the YZ plane, It is 11.25mm; X1 It is 60°; X2 It is 60°; It is 7.5mm; It is 7.5mm; t x1 It is 0.9mm; t x2 It is 0.3mm.

[0058] In the three-dimensional honeycomb structure, the thickness of the oblique outer rib 10 in the honeycomb cell facing the XZ plane is greater than the thickness of the oblique inner rib 40; the thickness of the oblique outer rib 10 in the honeycomb cell facing the YZ plane is greater than the thickness of the oblique inner rib 40. The honeycomb cells facing the XZ plane and the honeycomb cells facing the YZ plane expand outward, so that both orthogonal planes exhibit a positive Poisson's ratio effect when compressed.

[0059] In this embodiment, as Figures 10 to 11 As shown, in the honeycomb cells facing the first plane, the thickness of the inner oblique rib 40 is greater than the thickness of the outer oblique rib 10, causing the honeycomb cells in the first plane to produce a negative Poisson's ratio effect when compressed; in the honeycomb cells facing the second plane, the thickness of the inner oblique rib 40 is greater than the thickness of the outer oblique rib 10, causing the honeycomb cells in the second plane to produce a negative Poisson's ratio effect when compressed. The above three-dimensional honeycomb structure is of the HS-NN type (Honeycomb Structure - Negative and Negative).

[0060] In the XZ plane, It is 11.25mm; Z1 It is 60°; Z2 It is 60°; It is 7.5mm; It is 7.5mm; t z1 It is 0.3mm; t z2 It is 0.9mm.

[0061] In the YZ plane, It is 11.25mm; X1 It is 60°; X2 It is 60°; It is 7.5mm; It is 7.5mm; t x1 It is 0.3mm; t x2 It is 0.9mm.

[0062] In the described three-dimensional honeycomb structure, the honeycomb cells facing the XZ plane and the honeycomb cells facing the YZ plane both have an inner rib thickness of 40 mm that is greater than the outer rib thickness of 10 mm. The honeycomb cells facing the XZ plane and the YZ plane contract inwards, causing both orthogonal planes to exhibit a negative Poisson's ratio effect under compression. At this point, the three-dimensional honeycomb structure simultaneously exhibits tensile and contractile characteristics in two mutually perpendicular directions, making it suitable for load-bearing scenarios requiring multi-directional energy absorption or impact resistance.

[0063] In this embodiment, a reinforcing plate is provided in the cell of the three-dimensional honeycomb near the boundary of the horizontal inner rib. The reinforcing plate is attached to the surface of the horizontal inner rib and extends along the rib direction. This reinforcing plate effectively enhances the local stiffness of the horizontal inner rib in the boundary region, suppresses stress concentration and premature buckling at the intersection of the horizontal and oblique inner ribs during compression, makes the load transfer within the structure smoother, and improves the load-bearing capacity and deformation coordination of the edge region of the three-dimensional honeycomb structure.

[0064] In this embodiment, the Poisson's ratio of the honeycomb structure ranges from -0.2 to 0.2.

[0065] A design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio, based on an energy-absorbing enhanced honeycomb structure with an adjustable positive and negative Poisson's ratio, includes the following steps:

[0066] Step S1: Combine the horizontal outer rib 30, the oblique outer rib 10, the oblique inner rib 40, the first horizontal inner rib 201 and the second horizontal inner rib 202 to form a honeycomb cell, and stretch the honeycomb cell to form a two-dimensional honeycomb plate.

[0067] Step S2: Arrange two two-dimensional honeycomb panels orthogonally along the first and second directions respectively, and extract the spatially overlapping area of ​​the two through Boolean operations, thereby transforming the geometric and mechanical properties of the two-dimensional honeycomb into a three-dimensional honeycomb structure.

[0068] Step S3: Triangular reinforcing plates 50 were additionally constructed at the boundary of the novel three-dimensional honeycomb structure formed by Boolean operations.

[0069] Step S4: Use the three-dimensional honeycomb structure as a basic unit to form an array, generating a periodic three-dimensional honeycomb structure.

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand and implement the present invention. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio, characterized in that, It includes several honeycomb cells, and multiple cells are arranged alternately along the X and Y directions to form cell groups. The cell groups are arranged in an array and connected along the Z direction to form a three-dimensional honeycomb. The honeycomb cell includes two horizontal outer ribs, four oblique outer ribs, four oblique inner ribs, a first horizontal inner rib, and a second horizontal inner rib. The four oblique inner ribs are divided into two groups of two, forming a first oblique inner rib group and a second oblique inner rib group, respectively. The two horizontal outer ribs and the four oblique outer ribs form a hexagon as the outer contour of the honeycomb cell. The first end of the first horizontal inner rib is connected to the left vertex of the hexagon of the honeycomb cell, and its second end extends inward. The first ends of the two oblique inner ribs of the first oblique inner rib group are connected to the second ends of the first horizontal inner rib, and the second ends of the two oblique inner ribs of the first oblique inner rib group are respectively connected to the upper left vertex and the lower left vertex of the hexagon of the honeycomb cell. The first end of the second horizontal inner rib is connected to the right vertex of the hexagon of the honeycomb cell, and its second end extends inward. The first ends of the two oblique inner ribs of the second oblique inner rib group are connected to the second ends of the second horizontal inner rib, and the second ends of the two oblique inner ribs of the second oblique inner rib group are respectively connected to the upper right vertex and the lower right vertex of the hexagon of the honeycomb cell. Specifically, by setting the thickness of the inner and outer oblique ribs, the honeycomb structure can generate a positive Poisson's ratio effect when under pressure, or a negative Poisson's ratio effect when under pressure. The X, Y, and Z directions are perpendicular to each other, wherein the X and Z directions form a first plane, and the Y and Z directions form a second plane; In the honeycomb cells facing the first plane, the thickness of the oblique outer rib is greater than the thickness of the oblique inner rib, causing the honeycomb cells in the first plane to produce a positive Poisson's ratio effect when compressed; in the honeycomb cells facing the second plane, the thickness of the oblique outer rib is less than the thickness of the oblique inner rib, causing the honeycomb cells in the second plane to produce a negative Poisson's ratio effect when compressed. In the three-dimensional honeycomb cell, a reinforcing plate is provided at the position of the horizontal inner rib near the boundary.

2. The three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio as described in claim 1, characterized in that, In the honeycomb cells facing the first plane, the thickness of the oblique outer ribs is greater than the thickness of the oblique inner ribs, so that the honeycomb cells of the first plane generate a positive Poisson's ratio effect when compressed. In the honeycomb cells facing the second plane, the thickness of the oblique outer ribs is greater than the thickness of the oblique inner ribs, causing the cell group in the second plane to produce a positive Poisson's ratio effect when compressed.

3. A three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio as described in claim 2, characterized in that, In the cell facing the first plane, the thickness of the oblique outer rib is less than the thickness of the oblique inner rib, causing the cell in the first plane to produce a negative Poisson's ratio effect when compressed; in the cell facing the second plane, the thickness of the oblique outer rib is less than the thickness of the oblique inner rib, causing the cell in the second plane to produce a negative Poisson's ratio effect when compressed.

4. A three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio as described in claim 1, characterized in that, The Poisson's ratio of the honeycomb structure ranges from -0.2 to 0.

2.

5. A design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio, characterized in that, Based on the three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio as described in any one of claims 1-4, the method comprises the following steps: Step S1: Combine the horizontal outer ribs, oblique outer ribs, oblique inner ribs, first horizontal inner ribs and second horizontal inner ribs to form a honeycomb cell, and stretch the honeycomb cell to form a two-dimensional honeycomb plate. Step S2: Arrange the two two-dimensional honeycomb panels orthogonally along the X and Y directions respectively, and extract the spatially overlapping area of ​​the two through Boolean operation, thereby transforming the two-dimensional honeycomb into a three-dimensional honeycomb structure.

6. The design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio as described in claim 5, characterized in that, It also includes step S3: constructing additional triangular reinforcing plates at the boundary of the three-dimensional honeycomb structure formed by Boolean operations.

7. The design method for a three-dimensional honeycomb structure with an isotropically adjustable Poisson's ratio as described in claim 5, characterized in that, It also includes step S4: arraying the three-dimensional honeycomb structure as a basic unit to generate a periodic three-dimensional honeycomb structure.

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