A three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio.

Abstract

This invention discloses a three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties, comprising: a negative Poisson's ratio outer frame and a negative stiffness disk; the negative Poisson's ratio outer frame includes: pillars, each with a receiving cavity of the same size and structure on opposite sides; sliding components, partially embedded in the receiving cavities, and several symmetrically arranged around the centerline of the pillars, the sliding components and pillars forming a complete cubic structure; the sliding components are hollow shell structures, and one or more sidewalls facing the inner wall of the receiving cavity can fit into the receiving cavity, with a notch at the center of opposite sides of any two adjacent sets of sliding components; the negative stiffness disk, in the shape of a suction cup, in multiple sets, arranged at the notches, used to constrain the initial relative position of the sliding components and pillars. This invention achieves two forms of energy absorption in one structure through the sliding friction between the sliding components and pillars and the buckling deformation of the negative stiffness disk, thereby improving the energy absorption capacity of the structure.

Description

Technical Field

[0001] This invention relates to the field of mechanical metamaterials technology, and more specifically to a three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio. Background Technology

[0002] In the industrial sector, especially in aerospace, the requirements for lightweight, vibration-isolated, and impact-resistant protective materials are becoming increasingly stringent. Metamaterials are materials with unique physical properties and special artificial structures. In the field of mechanical metamaterials, metamaterials with negative Poisson's ratio and negative stiffness exhibit good vibration isolation and impact resistance performance. Therefore, the research on mechanical metamaterials is of great significance.

[0003] Currently, there is limited research on metamaterials that simultaneously possess negative stiffness and negative Poisson's ratio properties. Furthermore, existing structures are limited to two-dimensional structures, and when used in the field of energy absorption, these structures can only achieve energy absorption through negative stiffness, while the negative Poisson's ratio properties do not play a role in energy absorption.

[0004] Therefore, there is an urgent need for a three-dimensional metamaterial structure that simultaneously possesses negative stiffness and negative Poisson's ratio properties and has better energy absorption capacity to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to disclose a three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties. By combining a negative Poisson's ratio outer frame structure with a negative stiffness disk as a connecting component, the energy absorption capacity of the structure is improved through the sliding friction between the sliding component and the intermediate support and the buckling deformation of the negative stiffness disk.

[0006] To achieve the above objectives, the present invention provides a three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties, comprising: a negative Poisson's ratio outer frame and a negative stiffness disk;

[0007] The negative Poisson's ratio outer frame includes:

[0008] The pillar has identical accommodating chambers on opposite sides.

[0009] A sliding component is partially embedded in the receiving cavity, and several are symmetrically arranged around the center line of the support column. Several of the sliding components and the support column can form a complete cubic structure.

[0010] The sliding component is a hollow shell structure, and one or more side walls facing the inner wall of the receiving cavity can fit into the receiving cavity. A notch is provided in the center of the opposite side of any two adjacent sets of sliding components.

[0011] Multiple sets of negative stiffness disks, shaped like suction cups, are arranged at the notch to constrain the initial relative position of the sliding component and the support. The suction surface of the negative stiffness disk faces the inside of the housing of the sliding component. A guide connecting post extends outward from the center of the back of the negative stiffness disk along the direction of the center line of the negative stiffness disk to form a guide connecting post. The guide connecting posts between two adjacent negative stiffness disks are connected to each other.

[0012] As a further improvement of the present invention, the sliding component has only one sidewall that is in contact with the inner wall of the receiving chamber, and the sidewall has an arcuate structure.

[0013] As a further improvement of the present invention, the sliding component has an inverted frustum structure.

[0014] As a further improvement of the present invention, the negative Poisson's ratio outer frame is a cube structure, consisting of eight hollow sliding parts and a solid central support section.

[0015] As a further improvement of the present invention, the substrate of the negative Poisson's ratio outer frame is made of a material with a high elastic modulus, and the substrate of the negative stiffness disk is made of a material with a low elastic modulus and good ductility.

[0016] As a further improvement of the present invention, the negative Poisson's ratio outer frame is made of resin, and the negative stiffness disk is made of polyurethane.

[0017] As a further improvement of the present invention, the negative Poisson's ratio outer frame is made of a metal material, such as aluminum alloy, and the negative stiffness disk is made of nylon.

[0018] As a further improvement of the present invention, the sliding member located at the edge of the notch is formed with an annular step for the outer edge of the negative stiffness disk to be fitted.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) A three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties is realized by combining a segmented cubic structure with a negative stiffness disk to achieve a three-dimensional double negative mechanical metamaterial structure. The sliding friction between the sliding component and the intermediate support and the buckling deformation of the negative stiffness disk realize two forms of energy absorption in one structure, thereby improving the energy absorption capacity of the structure. At the same time, this application can realize the reuse of the structure through the elastic deformation of the negative stiffness structure and the sliding friction of the negative Poisson's ratio outer frame. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio in Embodiment 1 of the present invention.

[0022] Figure 2 is Figure 1 a top - view structural schematic diagram of

[0023] Figure 3 is Figure 1 a three - dimensional structural schematic diagram of the sliding component in

[0024] Figure 4 is a three - dimensional structural schematic diagram of a three - dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio performance in the second embodiment of the present invention;

[0025] Figure 5 is a three - dimensional structural schematic diagram of a three - dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio performance in the third embodiment of the present invention;

[0026] Figure 6 is the negative stiffness response trend curve of a three - dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio performance of the present invention.

[0027] In the figure: 10, accommodation chamber; 11, strut; 12, sliding component; 21, negative stiffness disc; 22, guiding connection column; 121, annular step; 120, notch. Detailed implementation manners

[0028] The present invention will be described in detail below in conjunction with the various implementation manners shown in the drawings. However, it should be noted that these implementation manners are not limitations on the present invention. Any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art based on these implementation manners shall fall within the protection scope of the present invention.

[0029] It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0030] Please refer to Figures 1 to 6 a specific implementation manner of a three - dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio performance of the present invention shown.

[0031] Embodiment 1:

[0032] Refer to Figure 1-3As shown, a three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties includes: a negative Poisson's ratio outer frame and a negative stiffness disk 21; the negative Poisson's ratio outer frame includes: a support column 11, with a receiving cavity 10 of the same size and structure opened on opposite sides; sliding components 12, partially embedded in the receiving cavity 10, and several of them are symmetrically arranged around the center line of the support column 11, and the sliding components 12 and the support column 11 can form a complete cubic structure; the sliding components 12 are hollow shell structures, and one or more side walls facing the inner wall of the receiving cavity 10 can be connected to the receiving cavity 10. The chambers 10 are fitted together, and a notch 120 is provided at the center of the opposite side of any two adjacent sets of sliding components 12. Multiple negative stiffness disks 21, shaped like suction cups, are arranged at the notches 120 to constrain the initial relative positions of the sliding components 12 and the support columns 11. The suction surface of the negative stiffness disks 21 faces inwards towards the housing of the sliding components 12. A guide connecting post 22 extends outwards from the center of the back of the negative stiffness disk 21 along its centerline towards the outside of the sliding component 12. The guide connecting posts 22 between any two adjacent negative stiffness disks 21 are connected opposite each other. The sliding component 12 located at the edge of the notch 120 forms an annular step 121 for the outer edge of the negative stiffness disk 21 to be fitted. The negative stiffness disks 21, as connecting components, can be fixed to the sliding components 12 by interference fit or adhesive. The negative stiffness disks 21 are fixedly connected to each other by the guide connecting posts 22 at their top ends.

[0033] In this embodiment, the negative Poisson's ratio outer frame is a cubic structure, consisting of eight hollow sliding components 12 and one solid support column 11. There are 16 negative stiffness disks 21 between the sliding components 12, which are fixedly connected. The connection method of the negative stiffness disks 21 constrains the initial relative position of the sliding components 12 and the central support column 11. The sliding component 12 has an inverted frustum structure, with two side walls that abut the inner wall of the receiving chamber 10, and these side walls are planar. To ensure complete deformation of the negative stiffness disks 21 and to meet the requirement of lightweight design, the sliding component 12 is a hollow shell structure, while the central support column 11 is a solid structure to increase stiffness and achieve relative sliding. The eight sliding components 12 sliding relative to the central support column 11 will eventually return to a cubic structure, thus achieving the negative Poisson's ratio performance.

[0034] More specifically, for the negative Poisson's ratio outer frame, 4 sliding components 12 at the upper and lower parts are respectively connected into a whole through negative stiffness disks 21. The lower sliding components 12 are directly placed on the fixed plane to restrict their displacements in the vertical direction. The middle struts 11 are directly placed on the lower sliding components 12, and the upper sliding components 12 are directly placed on the middle struts 11, thus realizing a complete double-negative metamaterial structural unit. More specifically, the side length of the cube structure is 40 mm, the reserved displacements for the upper and lower sliding are 3 mm respectively, the height of the negative stiffness disk 21 is 3.5 mm, the diameter is 10 mm, and the thickness is 0.4 mm. The negative Poisson's ratio effect of the compressed structure will cause the overall structure to shrink into a cube, and the negative stiffness effect will obtain a force-displacement response curve as shown in Figure 6 shown.

[0035] The base material of the negative Poisson's ratio outer frame is made of a material with a large elastic modulus, such as resin; the base material of the negative stiffness disk 21 is made of a material with a small elastic modulus and good ductility, such as polyurethane.

[0036] Embodiment 2:

[0037] Refer Figure 4 as shown, only one side wall of the sliding component 12 is in contact with the inner wall of the accommodating chamber 10, and this side wall has an arc-shaped structure. There are 16 groups of sliding components 12, 8 groups of struts 11 at the upper and lower parts respectively, 32 groups of negative stiffness disks 21, and the negative Poisson's ratio outer frame is a cylindrical structure. For other technical features, please refer to Embodiment 1 and will not be elaborated here.

[0038] Embodiment 3:

[0039] Refer Figure 5 as shown, there are 12 groups of sliding components 12, 6 groups of struts 11 at the upper and lower parts respectively, 24 groups of negative stiffness disks 21, and the negative Poisson's ratio outer frame is a hexagonal prism structure. For other technical features, please refer to Embodiment 1 and will not be elaborated here.

[0040] Embodiment 4:

[0041] The negative Poisson's ratio outer frame is made of a metal material, such as aluminum alloy, and the negative stiffness disk 21 is made of nylon. For other technical features, please refer to Embodiment 1 and will not be elaborated here.

[0042] In addition, it should be understood that although this specification is described according to the embodiments, not each embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A three-dimensional mechanical metamaterial structure having negative stiffness and negative Poisson's ratio properties, characterized in that, Comprise: a negative Poisson's ratio outer frame and a negative stiffness disc; the negative Poisson's ratio outer frame comprises: a support, which has a receiving cavity of the same size and structure on each side; a sliding component, which is partially embedded in the receiving cavity and is arranged symmetrically to the center line of the support, and a plurality of sliding components and the support can form a complete cube structure; the sliding component is a hollow shell structure, and one or more sides of the sliding component facing the inner wall of the receiving cavity can be fitted with the receiving cavity, and a gap is formed in the center of the opposite side of any two adjacent groups of sliding components; the negative stiffness disc is in the shape of a suction disc, has a plurality of groups, and is arranged at the gap for constraining the initial relative position of the sliding component and the support, the adsorption surface of the negative stiffness disc faces the shell inside the sliding component, and the back of the negative stiffness disc extends outward from the sliding component along the direction of the center line of the negative stiffness disc to form a guide connecting column, and the guide connecting columns of two adjacent negative stiffness discs are connected in opposition.

2. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties according to claim 1, characterized in that, The sliding component only has one side wall fitted with the inner wall of the receiving cavity, and the side wall is in the shape of an arc surface.

3. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties of claim 1, wherein, The sliding component is in the shape of an inverted truncated pyramid.

4. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties of claim 1, wherein, The negative Poisson's ratio outer frame is in the shape of a cube, which is composed of eight hollow sliding components and one solid middle support part.

5. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties of claim 1, wherein, The negative Poisson's ratio outer frame is made of resin, and the negative stiffness disc is made of polyurethane.

6. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties of claim 1, wherein, The negative Poisson's ratio outer frame is made of metal material, and the negative stiffness disc is made of nylon.

7. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties according to claim 6, characterized in that, The negative Poisson's ratio outer frame is made of aluminum alloy.

8. The three-dimensional mechanical metamaterial structure with negative stiffness and negative Poisson's ratio properties of claim 1, wherein, The edge of the gap of the sliding component is formed with an annular step for fitting the outer edge of the negative stiffness disc.

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