A double-material curved-edge concave negative poisson's ratio sandwich plate considering material gradient and structure gradient design simultaneously

Abstract

The application relates to the technical field of honeycomb sandwich structures, in particular to a double-material curved-edge inner-concave negative Poisson's ratio sandwich plate design method considering material gradient and structure gradient design simultaneously. The method comprises an upper end plate, a core layer and a lower end plate, the core layer is arranged between the upper end plate and the lower end plate and is fixedly connected with the upper end plate and the lower end plate; the core layer is a double-material curved-edge negative Poisson's ratio gradient honeycomb layer structure, and the core layer is obtained by stretching the rear of a double-material inner-concave curved-edge negative Poisson's ratio cell transversely. The internal structure of the plate layer is restructured, so that the problem that lightweight safety cannot be considered simultaneously in the automobile design and production process is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of honeycomb sandwich structures, and particularly relates to a design method of a double-material curved-edge concave negative Poisson's ratio sandwich panel considering material gradient and structure gradient design. BACKGROUND

[0002] Poisson's ratio refers to the negative of the ratio of transverse normal strain to longitudinal normal strain when the material is subjected to uniaxial tension or compression. Most natural materials in nature are positive Poisson's ratio, and the transverse length of a negative Poisson's ratio material will be longer after longitudinal elongation instead of contraction, which is also called auxetic material. This special deformation effect makes it have better impact resistance, shock absorption and energy absorption effect than positive Poisson's ratio materials. In 1987, Lakes obtained a kind of negative Poisson's ratio material with special microstructure, which has developed rapidly as a kind of mechanical super material since then. With the maturity of processing technology, more and more kinds of negative Poisson's ratio materials can be processed by additive manufacturing technology, and the excellent performance of the negative Poisson's ratio materials and structures has great potential applications in many fields (such as some special parts used in aerospace, medical health, building, etc.).

[0003] At present, most of the existing negative Poisson's ratio cells are composed of a single material. By referring to the design idea of composite materials, the combination of different materials is considered, and this idea is applied to the design of negative Poisson's ratio cell structure. Compared with single-material negative Poisson's ratio structure, the multi-material cell design can combine the negative Poisson's ratio characteristics with the excellent performance of the material combination. The honeycomb material has the characteristics of light weight, high specific stiffness and strong stability. Compared with solid plates, the impact resistance and shock absorption effect of the honeycomb material is more perfect, and the cost is more saved. Not only the material properties will affect the mechanical properties of the cell, but also the arrangement mode of different cells will affect the energy absorption effect of the structure. Compared with the structure with uniform arrangement mode, the reasonable gradient arrangement structure can play a significant advantage in reducing the initial force peak, enhancing the impact resistance and energy absorption capacity, etc. At present, with the development of negative Poisson's ratio and additive technology, more and more scholars apply negative Poisson's ratio structure to honeycomb sandwich panel. The double-material negative Poisson's ratio structure has different deformation failure modes when it is crushed, and shows excellent energy absorption characteristics, and the combination of the three can play a greater advantage.

[0004] At present, the use rate of automobiles is getting higher and higher, and it has become an essential tool for people to travel, so its safety is more concerned. While meeting the light weight to ensure green environmental protection and energy saving, the anti-collision and impact resistance performance should also be considered to ensure safety. However, the existing plate cannot meet both requirements at present. Light weight cannot ensure safety, and too heavy design makes the automobile unable to ensure economy. It is an urgent problem to design a new structure to make the sandwich panel light and safe. SUMMARY

[0005] The present disclosure provides a design method of a double-material curved edge concave negative Poisson's ratio sandwich plate considering material gradient and structure gradient design simultaneously, which reconstructs the internal structure of the plate layer, thereby solving the problem that lightweight safety cannot be considered simultaneously in the process of automobile design and production.

[0006] In a first aspect, the present disclosure provides a double-material curved edge concave negative Poisson's ratio sandwich plate considering material gradient and structure gradient design simultaneously, comprising an upper end plate, a core layer and a lower end plate, the core layer is arranged between the upper end plate and the lower end plate, and is fixedly connected with the upper end plate and the lower end plate; the core layer is a double-material curved edge negative Poisson's ratio gradient honeycomb layer structure, the core layer is composed of longitudinally gradient arranged different bearing units, the bearing unit is obtained by transversely arraying and then stretching the double-material concave curved edge negative Poisson's ratio cell.

[0007] Preferably, the double-material curved edge cell is composed of two different materials in transverse and longitudinal directions, and by adjusting the cell size and material composition, the transverse array and out-of-plane stretching sequentially form different kinds of bearing units, the bearing units form the core layer through different gradient arrangement modes, the double-material curved edge cell is connected with a connecting rod, the connecting rod is the same as the double-material curved edge material, and the double-material curved edge body is a strip structure.

[0008] Preferably, the double-material curved edge cell is prepared by 3D printing or wire cutting technology.

[0009] Preferably, the double-material curved edge cell is composed of two different materials in transverse and longitudinal directions, and by adjusting the cell size and material composition, the transverse array and out-of-plane stretching sequentially form different kinds of bearing units, the bearing units form the core layer through different gradient arrangement modes, the double-material curved edge cell is connected with a connecting rod, the connecting rod is the same as the double-material curved edge material, and the double-material curved edge body is a strip structure.

[0010] Preferably, the double-material curved edge negative Poisson's ratio cell is stretched to form a single bearing unit, the transverse array of the single bearing unit forms a bearing unit body, and the core layer is composed of different bearing units arranged longitudinally in gradient.

[0011] Preferably, the bearing units after arraying are connected with each other through the connecting rods, and the connecting rods are fixedly connected with the upper and lower plates perpendicularly.

[0012] Preferably, the bearing unit is stretched after arraying different cells, and a single cell is stretched to form a single bearing body.

[0013] In a second aspect, the present disclosure provides a preparation method of a double-material curved edge negative Poisson's ratio gradient honeycomb sandwich plate, comprising the following steps:

[0014] (1) selecting an initial negative Poisson's ratio cell, changing its geometric parameters to obtain cells with different structural properties; (2) the transverse rods and longitudinal rods are composed of different materials to obtain cells with different material properties;

[0015] (3) different geometric parameters and material parameters are used to construct different cells, and based on the cells, a single load-bearing unit is formed after out-of-plane stretching, and the single load-bearing unit is arrayed transversely to form a single-layer load-bearing unit body of the core layer, and different gradient modes of the core layer are formed by changing the arrangement order of the single layer, and the load-bearing units after arraying are connected by the connecting rods;

[0016] (4) the core layer is fixed between the upper end plate and the lower end plate, and the connecting rods are fixedly connected with the face plate.

[0017] Preferably, in step (2), the material includes aluminum, copper and steel.

[0018] In summary, the present application has the following beneficial effects:

[0019] 1. The double-material curved edge negative Poisson's ratio honeycomb sandwich plate provided in the present application is composed of upper and lower aluminum alloy plates and a double-material curved edge negative Poisson's ratio gradient honeycomb sandwich layer, uses a double-material curved edge structure as a cell, has a negative Poisson's ratio effect, and has a stronger buffering, shock-absorbing and energy-absorbing effect than a traditional laminate form when the face plate is subjected to impact load.

[0020] 2. The sandwich structure is applied to a car body or an energy-absorbing box in the present application, which can absorb more energy when the car body is subjected to impact while ensuring the light weight of the car body, thereby ensuring the safety of the car body.

[0021] 3. The double-material curved edge negative Poisson's ratio sandwich plate considering material gradient and structural gradient design simultaneously in the present application restructures the internal structure of the plate layer, thereby solving the problem that light weight and safety cannot be considered simultaneously in the process of car design and production.

[0022] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the protection scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0023] 1、 Figure 1 is a schematic diagram of the overall structure of the double-material curved edge negative Poisson's ratio sandwich plate considering material gradient and structural gradient design simultaneously in the present application, wherein 1 is an upper end plate, 2 is a sandwich layer, and 3 is a lower end plate.

[0024] 2、 Figure 2 is a XOY plane schematic diagram of the double-material curved edge negative Poisson's ratio sandwich plate considering material gradient and structural gradient design simultaneously in the present application.

[0025] 3、Figure 3 is the schematic diagram of the double-material curved edge negative Poisson's ratio cell in the present application;

[0026] 4、 Figure 4 is the schematic diagram of the deformation mechanism of the double-material curved edge negative Poisson's ratio cell in the present application;

[0027] 5、 Figure 5 is the variation trend of the equivalent Poisson's ratio of the double-material curved edge negative Poisson's ratio cell in the present application with the modulus ratio k parameter;

[0028] 6、 Figure 6 is the variation trend of the equivalent Poisson's ratio of the double-material curved edge negative Poisson's ratio cell in the present application with the angle parameter;

[0029] 7、 Figure 7 is the schematic diagram of a single load-bearing unit of the double-material curved edge negative Poisson's ratio gradient honeycomb sandwich plate in the present application;

[0030] 8、 Figure 8 is the schematic diagram of a single layer of the sandwich layer of the double-material curved edge negative Poisson's ratio gradient honeycomb sandwich plate in the present application;

[0031] 9、 Figure 9 is the schematic diagram of the core layer of the double-material curved edge negative Poisson's ratio sandwich plate considering the material gradient and the structural gradient design in the present application, wherein (a) positive gradient; (b) negative gradient; (c) symmetric positive gradient; (d) symmetric negative gradient. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to the following examples, it is particularly pointed out that: in the following examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used, and the raw materials used in the following examples can be obtained from ordinary market sales unless otherwise specified.

[0033] Examples

[0034] Example 1

[0035] A double-material curved edge negative Poisson's ratio honeycomb sandwich plate comprises:

[0036] Step one, select an initial negative Poisson's ratio cell, change its geometric parameters to obtain cells with different structural properties.

[0037] Step two, consider different constituent materials of the transverse rods and the longitudinal rods to obtain cells with different material properties, the following table is the selected materials and the composition method.

[0038] Table 1 Material parameters

[0039]

[0040] Table 2 Double-material combination method in cell

[0041]

[0042] Step three, different cells are constructed by considering size parameters and material parameters, and the cells are stretched out of plane to form a single load-bearing unit, which is arrayed transversely to form a single-layer core layer main body, and different gradient patterns of the core layer are formed by changing the arrangement order of the single layer, and the arrayed load-bearing units are connected by connecting rods.

[0043] Step four, the core layer is fixed between the upper and lower plates, and the connecting rods are fixedly connected with the face plate. 3D printing is used to prepare the material.

[0044] Example 2

[0045] A double-material curved edge negative Poisson's ratio gradient honeycomb core layer of a sandwich plate considering material gradient and structure gradient design simultaneously, comprising:

[0046] Step 1, determine the cell shape and adjustable parameters.

[0047] Step 2, different cells are constructed by changing cell structure parameters θ and material parameters k.

[0048] Step 3, the cells are stretched as a whole to form a single load-bearing unit.

[0049] Step 4, the load-bearing units are arrayed transversely and connected by connecting rods to form a single-layer core layer main body load-bearing unit.

[0050] Step 5, different single-layer core layers are combined longitudinally to form a gradient honeycomb core layer.

[0051] Step 6, by simulating impact simulation, the relative density of the core layer is significantly lower than that of the traditional layer plate, and the unit mass energy absorption rate is significantly improved compared with the single-material honeycomb plate.

[0052] Step 7, use 3D printing or wire cutting technology to prepare the finished product.

[0053] Referring to Figures 1 to 6 A double-material curved edge negative Poisson's ratio gradient honeycomb sandwich plate is shown, comprising: an upper end plate 1, a core layer 2, and a lower end plate 3.

[0054] A single load-bearing unit is formed by stretching a double-material curved edge negative Poisson's ratio cell out of plane, different single load-bearing units are arrayed transversely to form different single-layer core layers, the single-layer core layers are connected by connecting rods to form the whole core layer 2, and different arrangement modes form different gradients.

[0055] Figure 3A schematic diagram of a double-material curved edge negative Poisson's ratio cell, different colors in horizontal and vertical directions represent different materials, black is material 1, blue is material 2, the elastic modulus of the horizontal and vertical materials is E2, E1, the ratio E1 / E2=k, the in-plane thickness is t, the out-of-plane thickness is b, the connecting rod length is m, the curved edge projection length is h, the curved edge radian is θ, the curved edge radius is r, F is the pressure, I is the moment of inertia of the rectangular cross-section of the rod about the neutral axis, I=bt 3 The equivalent Poisson's ratio expression of / 12 is:

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] The embodiment is an application of a double-material curved edge negative Poisson's ratio gradient honeycomb sandwich panel in an automobile energy absorption box.

[0064] The automobile energy absorption box is mainly used to quickly absorb and consume the energy brought by external impact when the automobile is subjected to external impact load. The sandwich panel described in embodiment 1 is used in the automobile energy absorption box, and the number of layers of the double-material curved edge negative Poisson's ratio gradient honeycomb core layer is appropriately selected according to the needs to meet the assembly requirements of the crash box. According to the impact simulation results in embodiment 1, the specific energy absorption of the double-material curved edge negative Poisson's ratio gradient honeycomb core layer is significantly improved compared with the traditional one, and the use of multiple core layers can maximize the absorption capacity of the automobile energy absorption box. While meeting the lightweight requirement, the passive safety performance of the automobile is effectively improved, and the safety of the passengers is effectively protected.

[0065] The above is only an exemplary specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or replacements within the technical range disclosed in the present disclosure can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A bimaterial curved concave negative Poisson's ratio sandwich panel that simultaneously considers material gradient and structural gradient design, characterized in that, It includes an upper end plate, a core layer, and a lower end plate. The core layer is placed between the upper end plate and the lower end plate and is fixedly connected to the upper end plate and the lower end plate. The core layer is a bimaterial curved negative Poisson's ratio gradient honeycomb layered structure, and the core layer is composed of different load-bearing units arranged in a longitudinal gradient. The dual-material concave curved edge negative Poisson's ratio cell is composed of two different materials in the transverse and longitudinal directions, and different core layers are formed by adjusting the cell size and material composition. The dual-material concave curved edge negative Poisson's ratio cell is connected to a connecting rod, and the connecting rod is made of the same material as the curved edge of the dual-material concave curved edge negative Poisson's ratio cell. The dual-material concave curved edge negative Poisson's ratio cell has arcs in both the horizontal and vertical directions; Different cells are constructed by changing the cell structure parameter θ and the material parameter k. The elastic moduli of the transverse and longitudinal materials are E2 and E1, respectively, k=E1 / E2, and θ is the curvature of the curved edge. The dual-material concave curved negative Poisson's ratio cell is stretched to form a single load-bearing unit. The single load-bearing unit is arrayed in the plane to form the main body of the load-bearing unit. The load-bearing units are arranged in different gradients to form the main body of the sandwich layer.

2. The dual-material curved concave negative Poisson's ratio sandwich panel according to claim 1, characterized in that, The dual-material curved support unit is fabricated using 3D printing or wire cutting technology.

3. The dual-material curved concave negative Poisson's ratio sandwich panel according to claim 1, characterized in that, The horizontal and vertical angles are arbitrary, the horizontal and vertical arc lengths are arbitrary arc lengths, the materials of the dual-material concave curved negative Poisson's ratio cell are different metal materials, and the connecting rods are perpendicular to each other.

4. The dual-material curved concave negative Poisson's ratio sandwich panel according to claim 1, characterized in that, The arrayed bearing units are interconnected by the connecting rods, which are vertically fixed to the upper and lower end plates.

5. The method for preparing the bimaterial curved concave negative Poisson's ratio sandwich panel according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Select an initial negative Poisson's ratio unit cell and change its size parameters to obtain cell cells with different structural properties; (2) The transverse and longitudinal directions of the cell are composed of different materials, resulting in cells with different material properties; (3) Different single cells are constructed with different size parameters and material parameters. Based on the single cell, they are stretched out of the plane to form a single bearing unit. The single bearing unit is arrayed laterally to form the main body of the sandwich single-layer bearing unit. By changing the arrangement order of the single layer, a core layer with different gradient modes is formed. The bearing unit after arraying is connected by the connecting rod. (4) The core layer is fixed between the upper end plate and the lower end plate, and the connecting rod is fixedly connected to the upper end plate and the lower end plate.

6. The method for preparing a dual-material curved concave negative Poisson's ratio sandwich panel according to claim 5, characterized in that, In step (2), the materials include aluminum, copper, and steel.

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