Energy absorption reinforced honeycomb structure with Poisson ratio adjustable in positive and negative directions and design method

Abstract

The invention discloses an energy-absorbing reinforced honeycomb structure with the Poisson's ratio capable of being adjusted positively and negatively and a design method, and relates to the field of honeycomb structures. Two horizontal outer ribs and four inclined outer ribs of the honeycomb structure form a hexagon; the two ends of the first arc-shaped inner rib are connected with the left upper vertex and the left lower vertex of the hexagon and are concave towards the left vertex of the hexagon; the second arc-shaped inner rib is connected with the right upper vertex and the right lower vertex of the hexagon and is concave towards the right vertex of the hexagon; two ends of one horizontal inner rib are respectively connected with the left vertex of the hexagon and the first arc-shaped inner rib, and two ends of the other horizontal inner rib are respectively connected with the right vertex of the hexagon and the second arc-shaped inner rib; and the circular ring is embedded in the convex parts of the two arc-shaped inner ribs. According to the honeycomb structure, the positive Poisson's ratio honeycomb and the negative Poisson's ratio honeycomb are fused through the two horizontal inner ribs, so that the inner ribs and the outer ribs are mutually balanced, the circular ring design is added, and the structural strength is improved; through the thickness parameter design of the inner ribs and the outer ribs, flexible transformation of the positive Poisson's ratio or the negative Poisson's ratio is achieved on the premise that light weight and high strength are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of honeycomb structure, and particularly relates to an energy-absorbing enhanced honeycomb structure with positive and negative Poisson's ratio and a design method. BACKGROUND

[0002] Lightweight honeycomb structures have important application value in the fields of aerospace, vehicle engineering and protective equipment, and the core challenge is to simultaneously achieve low density, high strength and controllable mechanical properties. Hexagonal honeycomb will appear a layered progressive collapse deformation mode under compression load, thereby realizing smooth energy absorption. Therefore, it has the characteristics of high energy absorption efficiency and is widely used in aircraft wing sandwich, automobile safes and satellite supports. However, it will spread laterally outward under compression load, showing a positive Poisson's ratio, which limits its application in scenarios that require deformation suppression or energy absorption enhancement. Traditional positive Poisson's ratio honeycomb structures will appear outward diffusion phenomenon when subjected to pressure, which will cause the local density of the material to decrease, and the anti-dishing property will also decrease, and under the action of out-of-plane bending moment, the traditional material will usually form a saddle-shaped surface with reverse bending curvature. As a typical negative Poisson's ratio metamaterial, the concave honeycomb will exhibit abnormal auxetic effect under compression load, and has excellent properties such as stronger fracture toughness, anti-dishing property and outstanding energy absorption capacity. These unique mechanical properties make the negative Poisson's ratio honeycomb have great application potential in the fields of bulletproof sandwich, variable wing flight skin and flexible robot joints.

[0003] In order to make the structure exhibit different Poisson's ratios, it is usually necessary to change the configuration of the structure, that is, to redesign the structure. In addition, in actual engineering applications, the change of the configuration means that the process needs to be changed and redesigned. For flexible and variable application scenarios, the traditional design method is time-consuming and laborious. Moreover, the classic hexagonal honeycomb and concave honeycomb structure also has the limitations of insufficient strength and poor controllable performance, which is difficult to meet the complex engineering requirements.

[0004] The traditional honeycomb structure has the problems of excessive process cost caused by topology reconstruction for Poisson's ratio sign conversion, insufficient strength and low energy absorption capacity. Specifically, the traditional structure can only exhibit a positive Poisson's ratio or a negative Poisson's ratio deformation mode under compression load. Moreover, due to the simple configuration of the traditional structure, the energy absorption mainly depends on the plastic energy absorption of the cell rib bending, but the number of plastic hinges generated during deformation is limited, which seriously limits the further improvement of the specific energy absorption of the honeycomb structure. SUMMARY

[0005] To solve the above problems, the application provides an energy-absorbing enhanced honeycomb structure with adjustable positive and negative Poisson's ratio and a design method.

[0006] In one aspect, the application provides an energy-absorbing enhanced honeycomb structure with adjustable positive and negative Poisson's ratio, wherein a cell of the honeycomb structure comprises two horizontal outer ribs, four inclined outer ribs, a first arc-shaped inner rib, a second arc-shaped inner rib, two horizontal inner ribs and a circular ring.

[0007] The two horizontal outer ribs and the four inclined outer ribs form a hexagon as an external contour of the cell of the honeycomb structure; the first arc-shaped inner rib connects the left upper vertex and the left lower vertex of the hexagon at two ends and is concave to the left vertex of the hexagon; the second arc-shaped inner rib connects the right upper vertex and the right lower vertex of the hexagon and is concave to the right vertex of the hexagon; one horizontal inner rib connects the left vertex of the hexagon and the first arc-shaped inner rib at two ends, and the other horizontal inner rib connects the right vertex of the hexagon and the second arc-shaped inner rib at two ends; and the circular ring is embedded in the convex parts of the two arc-shaped inner ribs.

[0008] Preferably, the first arc-shaped inner rib and the second arc-shaped inner rib are sinusoidal ribs, and the formula of the sinusoidal rib is as follows:

[0009] ;

[0010] ;

[0011] ;

[0012] wherein, y represents a dependent variable, x represents an independent variable; A represents an amplitude, T represents a period, φ represents a phase, L represents a longitudinal translation parameter, L represents a horizontal outer rib, D represents a diameter of the circular ring, θ represents an included angle between the horizontal inner rib and the inclined outer rib, and L represents a length of the inclined outer rib.

[0013] Preferably, the ribs of the honeycomb structure satisfy a thickness relationship, so that the inclined outer ribs yield preferentially to generate a negative Poisson's ratio effect when the honeycomb structure is compressed.

[0014] Preferably, the ribs of the honeycomb structure satisfy a thickness relationship such that the arc-shaped design of the arc-shaped inner ribs induces early yielding when the honeycomb structure is under compression, the transverse expansion pushed by the oblique outer ribs induces positive Poisson's ratio, and the circular ring is stretched to produce a passive stretching effect.

[0015] Preferably, the ribs of the honeycomb structure satisfy a thickness relationship such that the honeycomb structure first produces a positive Poisson's ratio effect and then produces a negative Poisson's ratio effect during compression.

[0016] A design method of an energy-absorbing enhanced honeycomb structure with adjustable positive and negative Poisson's ratio, comprising the following steps:

[0017] S1, taking the energy-absorbing enhanced honeycomb structure with adjustable positive and negative Poisson's ratio as a prototype honeycomb structure;

[0018] S2, setting the thickness of each rib of the prototype honeycomb structure and drawing a three-dimensional model to obtain a honeycomb structure three-dimensional model; the entity of the honeycomb structure three-dimensional model produces a positive Poisson's ratio effect, a negative Poisson's ratio effect, or a positive Poisson's ratio effect first and then a negative Poisson's ratio effect when under compression.

[0019] Preferably, the S2 further comprises adjusting the strength of the honeycomb structure by adjusting the thickness of the circular ring.

[0020] Preferably, after S2, it further comprises S3, manufacturing a honeycomb structure entity according to the honeycomb structure three-dimensional model.

[0021] Preferably, the S2 specifically comprises: setting the thickness of the four oblique outer ribs to be equal, and setting the thickness of the first arc-shaped inner rib and the second arc-shaped inner rib to be equal; setting the thickness difference coefficient to be greater than or equal to a first thickness difference coefficient threshold value to obtain a honeycomb structure that produces a positive Poisson's ratio effect when under compression; or setting the thickness difference coefficient to be less than a second thickness difference coefficient threshold value to obtain a honeycomb structure that produces a negative Poisson's ratio effect when under compression; or setting the thickness difference coefficient to be less than the first thickness difference coefficient threshold value and greater than or equal to the second thickness difference coefficient threshold value to obtain a honeycomb structure that first produces a positive Poisson's ratio effect and then produces a negative Poisson's ratio effect during compression.

[0022] The thickness difference coefficient is expressed as:

[0023] ;

[0024] Wherein, The thickness difference coefficient is expressed as: The thickness of the oblique outer rib is expressed as: The thickness of the arc-shaped inner rib is expressed as:

[0025] Preferably, the first thickness difference coefficient threshold value is 0, and the second thickness difference coefficient threshold value is -0.15.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) The present application fuses the positive Poisson ratio regular hexagonal honeycomb and the negative Poisson ratio concave hexagonal honeycomb through two horizontal ribs, and effectively improves the strength of the overall structure by using the mutual restraint of the opposite deformation trends of the two under compression load, thereby solving the problem of insufficient strength of the traditional honeycomb structure.

[0028] (2) The present application uses the thickness difference of the inner and outer ribs as a control means, and actively controls the deformation mode of the structure under compression by changing the relative thickness of the inner and outer ribs; under the premise of not changing the basic structure configuration, the flexible and controllable switching of the Poisson ratio between positive and negative values can be realized only by parameterized design, which greatly simplifies the design change process, avoids the complex topology reconstruction and corresponding process adjustment due to the change of the Poisson ratio demand in the traditional method, and significantly reduces the process complexity and cost.

[0029] (3) The circular ring introduced in the present application not only strengthens the structure, but also exhibits different mechanical behaviors in different deformation modes; the thickness of the circular ring can be adjusted to adjust the strength of the honeycomb structure, so that the size of the circular ring becomes a key adjustable design parameter, which can finely control the mechanical properties of the structure, provides unprecedented design freedom for integrating multiple functions in a single structure and adapting to diversified application scenarios, and truly realizes the concept of "function programmable structure". BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application will be further described in detail below with reference to the accompanying drawings;

[0031] Figure 1 The present application is a Poisson ratio positive and negative adjustable energy absorption and enhancement honeycomb structure unit;

[0032] Figure 2 The present application is a Poisson ratio positive and negative adjustable energy absorption and enhancement honeycomb structure design method schematic diagram;

[0033] Figure 3 The present application is a Poisson ratio positive and negative adjustable energy absorption and enhancement honeycomb structure unit parameter marking diagram;

[0034] Figure 4 The present application is a Poisson ratio positive and negative adjustable energy absorption and enhancement honeycomb structure schematic diagram;

[0035] Figure 5 The present application is a Poisson ratio positive and negative adjustable energy absorption and enhancement honeycomb structure thickness difference coefficient and Poisson ratio relationship schematic diagram;

[0036] Figure 6AHR-1 honeycomb cell of the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure of the embodiment of the present application;

[0037] Figure 7 AHR-2 honeycomb cell of the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure of the embodiment of the present application;

[0038] Figure 8 AHR-3 honeycomb cell of the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure of the embodiment of the present application;

[0039] Figure 9 AHR-1, AHR-2 and AHR-3 honeycomb structure Poisson's ratio comparison chart of the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure under quasi-static out-of-plane compression of the embodiment of the present application;

[0040] Figure 10 AHR-1 honeycomb and equal-area-density concave hexagonal and traditional honeycomb structure bearing strength comparison chart of the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure under quasi-static out-of-plane compression of the embodiment of the present application;

[0041] The drawings show that the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure cell 1 includes inclined outer ribs 11, horizontal outer ribs 12, arc-shaped inner ribs 13, horizontal inner ribs 14 and a circular ring 15. DETAILED DESCRIPTION

[0042] The present application will be further described below through specific embodiments.

[0043] A Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure, as Figure 1 The drawings show that the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure cell 1 includes inclined outer ribs 11, horizontal outer ribs 12, arc-shaped inner ribs 13, horizontal inner ribs 14 and a circular ring 15.

[0044] The Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure cell 1 of the embodiment can be regarded as a combination of traditional hexagonal honeycomb and concave hexagonal honeycomb, as follows:

[0045] Under compression load, the traditional hexagonal honeycomb usually presents positive Poisson's ratio characteristics, and the inclined ribs move laterally to both sides. While the concave hexagonal honeycomb shows opposite mechanical behavior, it presents negative Poisson's ratio characteristics under compression load, and its inclined ribs move laterally to the center. As Figure 2 The drawings show that the Poisson's ratio positive and negative adjustable energy absorption enhanced honeycomb structure cell 1 includes inclined outer ribs 11, horizontal outer ribs 12, arc-shaped inner ribs 13, horizontal inner ribs 14 and a circular ring 15. Figure 1The cellular configuration is shown. Two different mechanical behaviors inside the unit will counteract each other, and the competition is expected to improve the structural strength and achieve the regulation of the Poisson's ratio. Replacing the straight inclined rib inside the concave unit with an arc-shaped rib can reduce the initial peak and improve the specific energy absorption, so on the basis of the concave hexagonal honeycomb, the concave inclined straight rib is replaced with an arc-shaped inner rib 13 (a sine curve is used in this embodiment), as shown in Figure 2 In addition, the addition of a circular ring component inside the concave unit can further improve the mechanical properties and energy absorption capacity of the concave honeycomb.

[0046] In this embodiment, the arc-shaped inner rib 13 is a sine rib, that is, a structure configuration whose line type is controlled by a sine function. The use of a sine curve can reduce the initial peak of the structure to some extent, making the deformation mode more stable. The general form of the sine function is:

[0047] ;

[0048] Among them, A, ω, φ and k are four core parameters, which respectively determine the amplitude, period, phase and longitudinal translation of the function image, and jointly shape the final shape of the sine curve. φ, k are 0, A and ω are controlled by other parameters, and are expressed as:

[0049] ;

[0050] ;

[0051] Among them, the parameters are as shown in Figure 3 represents the length of the horizontal outer rib 12; represents the length of the inclined outer rib 11; represents the angle formed by the horizontal inner rib 14 and the inclined outer rib 11; represents the diameter of the circular ring 15.

[0052] The thickness difference coefficient of the inclined outer rib and the sine rib is defined as:

[0053] ;

[0054] Among them, represents the thickness difference coefficient; represents the thickness of the inclined outer rib; represents the thickness of the sine rib.

[0055] Figure 5 ​The relationship between the thickness difference coefficient and Poisson's ratio is shown. When the thickness difference coefficient is greater than or equal to 0, the honeycomb structure produces a positive Poisson's ratio effect under pressure; when the thickness difference coefficient is less than -0.15, the honeycomb structure produces a negative Poisson's ratio effect under pressure; when the thickness difference coefficient is between 0 and -0.15 or is -0.15, the honeycomb structure first produces a positive Poisson's ratio effect and then a negative Poisson's ratio effect under pressure.

[0056] To better illustrate the situation, three energy-absorbing enhanced honeycomb structures with adjustable Poisson's ratio (AHR-1, AHR-2, and AHR-3 honeycomb) with different parameter configurations were designed, as follows:

[0057] like Figure 6 As shown, the inner and outer ribs of the AHR-1 honeycomb structure cell are of equal thickness. The thickness of the oblique outer rib 11, horizontal outer rib 12, arc-shaped inner rib 13, and horizontal inner rib 14 is 0.7 mm, and the thickness of the ring 15 is 0.5 mm. Figure 4 As shown, the sample dimensions of the honeycomb structure are 79.5 mm in length, 20 mm in width, and 39.5 mm in height.

[0058] AHR-2 and AHR-3 use different thickness combinations. For example... Figure 7 As shown, the thickness of the oblique ribs in the AHR-2 honeycomb structure cell is smaller than that of the sinusoidal ribs. Specifically, the thickness of the oblique outer rib 11 is 0.5 mm, the thickness of the horizontal outer rib 12 is 0.7 mm, the thickness of the arc-shaped inner rib 13 is 0.9 mm, and the thickness of the circular ring 15 is 0.5 mm. The sample dimensions of the honeycomb structure are 79.5 mm in length, 20 mm in width, and 39.5 mm in height.

[0059] like Figure 8 As shown, the thickness of the oblique ribs in the AHR-3 honeycomb structure cell is greater than that of the sinusoidal ribs. Specifically, the thickness of the oblique outer rib 11 is 0.9 mm, the thickness of the horizontal outer rib 12 is 0.7 mm, the thickness of the arc-shaped inner rib 13 is 0.5 mm, and the thickness of the circular ring 15 is 0.5 mm. The sample dimensions of the honeycomb structure are 79.5 mm in length, 20 mm in width, and 39.5 mm in height.

[0060] The prepared samples were subjected to quasi-static compression tests in a universal testing machine to obtain the mechanical properties of the novel honeycomb structure. The samples were placed on a fixed base, and the upper indenter compressed them at a constant rate of 4 mm / min to minimize dynamic effects.

[0061] like Figure 9As shown, according to experimental results, the AHR-1 honeycomb structure significantly improves mechanical properties in the elastic stage through the intense competition between diagonal and sinusoidal ribs and the lateral constraint of the circular ring. AHR-2 exhibits a significant negative Poisson's ratio effect due to the preferential yielding of the diagonal straight ribs. The circular ring, under compression, generates a supporting effect and forms a triangular supporting structure with the horizontal ribs, significantly enhancing stiffness. AHR-3, due to the arc design of the sinusoidal ribs inducing early yielding, and the lateral expansion driven by the diagonal straight ribs triggering a positive Poisson's ratio, while the circular ring, under tension, generates a passive tensile effect. Figure 10 As shown in the comparison study with other novel honeycomb structures, AHR honeycomb exhibits superior mechanical properties. In particular, compared with classic concave honeycomb structures, its yield strength, average crushing stress, and energy absorption per unit mass are increased by 237.76%, 67.82%, and 54.53%, respectively. This method of improving structural performance by using internal and external ribs to balance each other provides a new approach for the design optimization of honeycomb structures.

[0062] In summary, this embodiment innovatively integrates a hexagonal honeycomb with a positive Poisson's ratio and a concave honeycomb with a negative Poisson's ratio into a hybrid unit using two horizontal ribs. The opposing deformation trends of these two elements create a mutual balance within the unit, significantly improving the overall stiffness, strength, and energy absorption capacity of the structure. The core of this design lies in achieving precise control over the dominant deformation mode under compressive loads without altering the basic topological configuration by differentiating the thickness of the inner and outer ribs. This allows for flexible adjustment of the Poisson's ratio, enabling it to switch between positive and negative values. Furthermore, introducing a ring structure within the unit further increases structural strength, resulting in a lightweight structure with high strength and excellent energy absorption performance. This method effectively overcomes the limitations of insufficient strength in traditional honeycomb structures, achieving programmable control of mechanical properties and Poisson's ratio. It provides a new approach for structural optimization design in high-tech engineering fields such as aerospace, biomedical implants, and energy absorption devices.

[0063] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A Poisson's ratio-adjustable energy-absorbing enhanced honeycomb structure, characterized in that, The cell of the honeycomb structure includes two horizontal outer ribs, four oblique outer ribs, a first arc-shaped inner rib, a second arc-shaped inner rib, two horizontal inner ribs, and a ring; Two horizontal outer ribs and four oblique outer ribs form a hexagon as the outer outline of the honeycomb structure cell; the first arc-shaped inner rib connects the upper left and lower left vertices of the hexagon at both ends and is concave towards the left vertex of the hexagon; the second arc-shaped inner rib connects the upper right and lower right vertices of the hexagon and is concave towards the right vertex of the hexagon; one horizontal inner rib connects the left vertex of the hexagon to the first arc-shaped inner rib at both ends, and the other horizontal inner rib connects the right vertex of the hexagon to the second arc-shaped inner rib at both ends; a ring is embedded in the convex part of the two arc-shaped inner ribs.

2. The energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 1, characterized in that, The first and second arc-shaped inner ribs are sinusoidal ribs; the formula for the sinusoidal rib is expressed as: ； ； ； in, Indicates the dependent variable. Indicates the independent variable; Indicates amplitude; Indicates period; Indicates phase; Indicates the longitudinal translation parameter; Indicates horizontal outer ribs; Indicates the diameter of the ring; Indicates the angle between the horizontal inner rib and the oblique outer rib; This indicates the length of the outer diagonal rib.

3. The energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 1, characterized in that, The ribs of the honeycomb structure satisfy a thickness relationship, which causes the outer ribs of the honeycomb structure to yield preferentially under pressure, resulting in a negative Poisson's ratio effect.

4. The energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 1, characterized in that, The ribs of the honeycomb structure satisfy the thickness relationship, so that when the honeycomb structure is under pressure, the arc design of the arc-shaped inner rib induces early yielding, the lateral expansion driven by the oblique outer rib triggers a positive Poisson's ratio, and the ring is stretched to produce a passive tensile effect.

5. The energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 1, characterized in that, The ribs of the honeycomb structure satisfy a thickness relationship, which causes the honeycomb structure to first generate a positive Poisson's ratio effect during the compression process, and then generate a negative Poisson's ratio effect.

6. A design method for an energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio, characterized in that, Based on the Poisson's ratio-adjustable energy-absorbing enhanced honeycomb structure according to any one of claims 1-5, the following steps are included: S1, using the energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio as the prototype honeycomb structure; S2, set the thickness of each rib in the prototype honeycomb structure and draw a three-dimensional model to obtain a three-dimensional model of the honeycomb structure; the solid of the three-dimensional model of the honeycomb structure produces a positive Poisson's ratio effect, a negative Poisson's ratio effect, or first produces a positive Poisson's ratio effect and then produces a negative Poisson's ratio effect when subjected to pressure.

7. The design method for an energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 6, characterized in that, The S2 further includes adjusting the strength of the honeycomb structure by adjusting the thickness of the ring.

8. The design method for an energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 6, characterized in that, Following S2, it also includes S3, which involves creating a cellular structure entity based on the 3D model of the cellular structure.

9. The design method for an energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 6, characterized in that, S2 specifically involves: making the thickness of the four oblique outer ribs equal, and the thickness of the first arc-shaped inner rib and the second arc-shaped inner rib equal; making the thickness difference coefficient greater than or equal to the first thickness difference coefficient threshold to obtain a honeycomb structure that produces a positive Poisson's ratio effect when under pressure. Alternatively, by making the thickness difference coefficient less than the second thickness difference coefficient threshold, a honeycomb structure that produces a negative Poisson's ratio effect under pressure can be obtained. Alternatively, the thickness difference coefficient can be made less than the first thickness difference coefficient threshold and greater than or equal to the second thickness difference coefficient threshold to obtain a honeycomb structure that first produces a positive Poisson's ratio effect and then produces a negative Poisson's ratio effect during the compression process. The thickness difference coefficient is expressed as: ； in, Indicates the thickness difference coefficient; Indicates the thickness of the oblique outer rib; This indicates the thickness of the curved inner rib.

10. The design method for an energy-absorbing enhanced honeycomb structure with adjustable Poisson's ratio according to claim 9, characterized in that, The first thickness difference coefficient threshold is 0; the second thickness difference coefficient threshold is -0.15.

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