A stability-enhanced asymmetric concave hexagonal honeycomb structure

Abstract

The application discloses a non-symmetrical concave hexagonal honeycomb structure with enhanced stability, comprising: a plurality of first type horizontal rods, a plurality of first type inclined rods and a plurality of second type inclined rods; the honeycomb structure is composed of a periodic array of concave polygonal cells, the number of cell edges N is a natural number and N>=3, at least one concave angle exists in the cell, the thickness of the first type horizontal rods is consistent, the thickness of the first type inclined rods is equal to the thickness of the first type horizontal rods, and the thickness of the first type inclined rods in the same cell remains consistent, and the thickness of the second type inclined rods is less than the thickness of the first type inclined rods, and the thickness of the second type inclined rods in the same cell remains consistent. The difference in bending stiffness ensures that the deformation proceeds in a predetermined order, avoids global buckling instability, enables the honeycomb structure to stably deform under large strain and maintain the negative Poisson's ratio effect, and improves the energy absorption efficiency and material utilization rate.

Description

Technical Field

[0001] This application relates to the field of mechanical metamaterial energy-absorbing structure technology, and more specifically, to an asymmetric concave hexagonal honeycomb structure with enhanced stability. Background Technology

[0002] Metamaterials are renowned for their superior mechanical behavior compared to natural materials. This exceptional behavior is attributed to their artificially designed microstructures, hence the name "metastructures." Among these, negative Poisson metamaterials have garnered significant attention due to their unique mechanical behavior: they exhibit expansion / compression under tension / compression. This unique deformation behavior enhances the overall mechanical properties of the structure, such as shear modulus, indentation resistance, fracture toughness, and energy absorption capacity. In recent years, their enhanced energy absorption properties have been widely applied in aerospace, automotive manufacturing, high-speed rail, and electronic product shock absorption and vibration damping devices, such as energy-absorbing boxes, engine vibration damping brackets, and inverter shock-resistant devices.

[0003] Among existing negative Poisson's ratio metamaterials, the traditional concave hexagonal structure is a typical and widely studied structure. Related research shows that honeycomb structures formed by arrays of traditional concave hexagonal structures have high porosity and are extremely prone to irreversible global buckling instability during compression, significantly reducing the advantages of the negative Poisson's ratio phenomenon. On the other hand, for energy-absorbing structures, buckling instability significantly reduces material utilization and greatly affects the structure's energy absorption performance. Therefore, there is an urgent need for a negative Poisson's ratio metamaterial with more stable deformation during compression to expand its practical applications. Summary of the Invention

[0004] To address the technical problems existing in the background art, this invention proposes an asymmetric concave hexagonal honeycomb structure with enhanced stability, comprising: multiple first-type horizontal rods, multiple first-type diagonal rods, and multiple second-type diagonal rods; the honeycomb structure is composed of periodically arrayed concave polygonal unit cells, the number of sides N of the unit cell is a natural number and N≥3, and there is at least one concave angle in the unit cell; the thickness of the first-type horizontal rods is consistent; the thickness of the first-type diagonal rods is equal to the thickness of the first-type horizontal rods, and the thickness of the first-type diagonal rods within the same unit cell is consistent; the thickness of the second-type diagonal rods is less than the thickness of the first-type diagonal rods, and the thickness of the second-type diagonal rods within the same unit cell is consistent.

[0005] Furthermore, N = 6, where there are 2 first-type horizontal bars, 2 first-type diagonal bars, and 2 second-type diagonal bars. The thickness of the first-type diagonal bars is greater than that of the second-type diagonal bars. In the unit cell, both ends of the first-type horizontal bars are connected to the first-type diagonal bars and the second-type diagonal bars respectively, and the other end of the first-type diagonal bars is connected to the second-type diagonal bars.

[0006] Furthermore, the cells are interconnected by sharing rods to form a periodic array structure.

[0007] Furthermore, it also includes multiple second-type horizontal bars, with unit cells connected to each other via second-type horizontal bars. The two ends of the second-type horizontal bars are respectively connected to the first-type connection points of two adjacent unit cells. The first-type connection points are the connection points between the first-type diagonal bars and the second-type diagonal bars within the unit cell. The second-type horizontal bars have the same thickness as the first-type horizontal bars.

[0008] Furthermore, in any unit cell, the following condition is satisfied:

[0009]

[0010] Where t1 is the thickness of the second type of inclined bar, t2 is the thickness of the first type of horizontal bar or the first type of inclined bar, θ1 is the angle between the second type of inclined bar and one of the first type of horizontal bars in the unit cell, θ2 is the angle between the first type of inclined bar and the first type of horizontal bar, and h is the distance between the two first type of horizontal bars in the unit cell.

[0011] Furthermore, the rod thickness ratio t1 / t2 is 2 / 5.

[0012] Furthermore, the deformation sequence of unit cells in the honeycomb structure can be controlled by adjusting the ratio of t1 to t2.

[0013] Furthermore, the ratio of the total length to the total height of the honeycomb structure is 1:1.

[0014] The beneficial effects of this invention are as follows: the difference in bending stiffness ensures that the deformation proceeds in a preset order, avoids global buckling instability, enables the honeycomb structure to deform stably under large strain and maintain the negative Poisson's ratio effect, and improves energy absorption efficiency and material utilization. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a schematic diagram of a dimensioned asymmetric concave hexagonal unit cell structure provided in an embodiment of the present invention;

[0017] Figure 2 These are schematic diagrams of an asymmetric concave hexagonal honeycomb structure with enhanced stability provided by embodiments of the present invention, as well as schematic diagrams of a traditional concave hexagonal honeycomb structure;

[0018] Figure 3 for Figure 2 Deformation process of two honeycomb structures under compression;

[0019] Figure 4 for Figure 2 Load-displacement curves of two honeycomb structures under compression;

[0020] Figure 5 for Figure 2 Energy absorption performance curves of two honeycomb structures under compression. Detailed Implementation

[0021] Reference Figure 1-5 This invention proposes an asymmetric concave hexagonal honeycomb structure with enhanced stability, comprising: multiple first-type horizontal rods 1, multiple first-type diagonal rods 2, and multiple second-type diagonal rods 3. The honeycomb structure is composed of periodically arrayed concave polygonal unit cells, where the number of sides N in each unit cell is a natural number and N≥3. Each unit cell contains at least one concave angle. The first-type horizontal rods 1 have a uniform thickness, the first-type diagonal rods 2 have the same thickness as the first-type horizontal rods 1, and the thickness of the first-type diagonal rods 2 within the same unit cell remains consistent, and the thickness of the second-type diagonal rods 3 is less than the thickness of the first-type diagonal rods 2, and the thickness of the second-type diagonal rods 3 within the same unit cell remains consistent. The difference in rod thickness creates a difference in bending stiffness, controlling the deformation sequence of the unit cells. This difference in bending stiffness ensures that deformation occurs in a preset order, avoiding global buckling instability, enabling the honeycomb structure to deform stably under large strain and maintain a negative Poisson's ratio effect, thereby improving energy absorption efficiency and material utilization.

[0022] In a specific embodiment, N = 6, wherein there are 2 first-type horizontal bars 1, 2 first-type diagonal bars 2, and 2 second-type diagonal bars 3, wherein the thickness of the first-type diagonal bar 2 is greater than the thickness of the second-type diagonal bar 3, and both ends of the first-type horizontal bar 1 in the unit cell are respectively connected to the first-type diagonal bar 2 and the second-type diagonal bar 3, and the other end of the first-type diagonal bar 2 is connected to the second-type diagonal bar 3.

[0023] To illustrate the significant advantages of the enhanced stability of the asymmetric concave hexagonal honeycomb structure, this invention conducts finite element simulations of two types of negative Poisson's ratio honeycombs from four perspectives, including the deformation process under compression, the change of the negative Poisson's ratio effect during deformation, the load-displacement curve, and the specific energy absorption curve.

[0024] The two types of honeycomb structures are a traditional concave hexagonal honeycomb structure with a t1:t2 ratio of 1 and an asymmetric concave hexagonal honeycomb structure with enhanced stability and a t1:t2 ratio of 0.4. Their compression tolerance is as follows: Figure 3 As shown, the dashed box indicates the initial position of the honeycomb. From Figure 3As can be seen, the traditional concave hexagonal honeycomb structure begins to exhibit local buckling instability at a strain of 0.1, and irreversible global instability occurs as compression progresses, with the negative Poisson's ratio effect disappearing. In contrast, the asymmetric concave hexagonal honeycomb structure, with its enhanced stability, exhibits remarkably stable deformation throughout the entire compression process. This difference in stability is also reflected in the force-displacement curves. Figure 4 It can be seen that instability severely reduces the load-bearing capacity of traditional concave hexagonal structures. For asymmetric concave hexagonal structures with enhanced stability, the overall force response is very stable, and its trend steadily increases with the presence of the negative Poisson's ratio effect. This difference in stability also means that asymmetric concave hexagonal structures with enhanced stability have more beneficial energy absorption properties.

[0025] Through simulation experiments comparing the stability-enhanced asymmetric concave hexagonal honeycomb structure with the traditional concave hexagonal honeycomb structure in four aspects, the advantages of the stability-enhanced asymmetric concave hexagonal honeycomb structure described in this invention are verified as follows:

[0026] 1. By changing the thickness of the rod, the bending stiffness can be varied, and the deformation process of the structure can be easily controlled, achieving stable deformation under large strain and maintaining the negative Poisson's ratio effect.

[0027] 2. Stable deformation and the negative Poisson's ratio effect under large deformation cause the asymmetric concave hexagonal honeycomb structure to exhibit a gradual upward force response trend.

[0028] 3. Compared with the traditional concave hexagonal honeycomb structure, the proposed asymmetric concave hexagonal honeycomb structure has higher energy absorption performance due to its stable deformation, which greatly improves the material utilization rate.

[0029] In a specific embodiment, the unit cells are interconnected via shared rods to form a periodic array structure. This shared connection method enhances the overall structural rigidity and stability while simplifying the manufacturing process, making it suitable for large-scale industrial production.

[0030] In a specific embodiment, the honeycomb structure is composed of m×n asymmetric concave hexagonal unit cells, where m and n are both positive integers. The honeycomb structure can be composed of any m×n unit cells (m and n are positive integers), and the array size can be flexibly adjusted according to actual needs. It provides high scalability, adapts to different application scenarios (such as energy-absorbing boxes, protective structures, etc.), and maintains consistent deformation stability even under large-scale arrays.

[0031] In a specific embodiment, it also includes multiple second-type horizontal bars 4, which connect the unit cells to each other. The two ends of the second-type horizontal bars 4 are respectively connected to the first-type connection points of two adjacent unit cells. The first-type connection points are the connection points of the first-type inclined bars 2 and the second-type inclined bars 3 within the unit cell. The second-type horizontal bars 4 have the same thickness as the first-type horizontal bars 1.

[0032] In a specific embodiment, the following condition is satisfied in any unit cell:

[0033]

[0034] Wherein, t1 is the thickness of the second type of diagonal member 3, t2 is the thickness of either the first type of horizontal member 1 or the first type of diagonal member 2, θ1 is the angle between the second type of diagonal member 3 and one of the two first type of horizontal members 1 in the unit cell, θ2 is the angle between the first type of diagonal member 2 and the first first type of horizontal member 1, and h is the distance between the two first type of horizontal members 1 in the unit cell. The geometric parameters of the unit cell include t1, t2, θ1, θ2, and h; where θ2 is defined by t1, t2, θ1, and h. The mathematical correlation between the parameters simplifies the structural design process and facilitates rapid optimization of structural performance by adjusting key parameters such as t1 / t2.

[0035] In a specific embodiment, the rod thickness ratio t1 / t2 is 2 / 5. Experiments or simulations have verified that this ratio maximizes the difference in bending stiffness. This ensures that the lower stiffness members deform preferentially, preventing premature failure of the higher stiffness members and significantly improving the structure's energy absorption efficiency and deformation stability.

[0036] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An asymmetric concave hexagonal honeycomb structure with enhanced stability, characterized in that, include: Multiple first-type horizontal bars (1), multiple first-type diagonal bars (2), and multiple second-type diagonal bars (3); the honeycomb structure is composed of periodically arrayed concave polygonal unit cells, the number of sides N of the unit cell is a natural number and N≥3, there is at least one concave angle in the unit cell, the thickness of the first-type horizontal bars (1) is consistent, the thickness of the first-type diagonal bars (2) is equal to the thickness of the first-type horizontal bars (1), and the thickness of the first-type diagonal bars (2) in the same unit cell is consistent, the thickness of the second-type diagonal bars (3) is less than the thickness of the first-type diagonal bars (2), and the thickness of the second-type diagonal bars (3) in the same unit cell is consistent.

2. The honeycomb structure according to claim 1, characterized in that, N = 6, where there are 2 first-type horizontal bars (1), 2 first-type diagonal bars (2), and 2 second-type diagonal bars (3). The thickness of the first-type diagonal bar (2) is greater than the thickness of the second-type diagonal bar (3). In the unit cell, the first-type horizontal bar (1) is connected to the first-type diagonal bar (2) and the second-type diagonal bar (3) at both ends, and the other end of the first-type diagonal bar (2) is connected to the second-type diagonal bar (3).

3. The honeycomb structure according to claim 2, characterized in that, Unit cells are interconnected by sharing rods to form a periodic array structure.

4. The honeycomb structure according to claim 2, characterized in that, It also includes multiple second-type horizontal bars (4), which connect the unit cells to each other. The two ends of the second-type horizontal bars (4) are respectively connected to the first-type connection points of two adjacent unit cells. The first-type connection point is the connection point between the first-type diagonal bar (2) and the second-type diagonal bar (3) in the unit cell. The second-type horizontal bars (4) have the same thickness as the first-type horizontal bars (1).

5. The honeycomb structure according to claim 4, characterized in that, In any unit cell, the following condition is satisfied: Where t1 is the thickness of the second type of inclined bar (3), t2 is the thickness of the first type of horizontal bar (1) or the first type of inclined bar (2), θ1 is the angle between the second type of inclined bar (3) and the first first type of horizontal bar (1) of the two first type of horizontal bars (1) in the unit cell, θ2 is the angle between the first type of inclined bar (2) and the first first type of horizontal bar (1), and h is the distance between the two first type of horizontal bars (1) in the unit cell.

6. The honeycomb structure according to claim 1, characterized in that, The rod thickness ratio t1 / t2 is 2 / 5.

7. The honeycomb structure according to claim 1, characterized in that, The deformation sequence of unit cells in a honeycomb structure can be controlled by adjusting the ratio of t1 to t2.

8. The honeycomb structure according to claim 1, characterized in that, The ratio of the total length to the total height of the honeycomb structure is 1:1.

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