A stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio

Abstract

The present invention discloses a stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio. This structure is based on a rotating polygon structure and a sandwich panel, and is manufactured using various connection methods. This structure can achieve horizontal stretching with a negative Poisson's ratio effect without affecting the vertical load-bearing capacity. Compared with ordinary sandwich panels, the proposed sandwich panel structure has significant improvements in terms of controllability, conformability, and curved surface co-directionality. These properties enable the sandwich panel structure to provide protection for complex objects such as non-Euclidean curved surfaces. The sandwich panel structure designed by the method of the present invention has been proven to have strong novelty and practicality. While realizing the function of the sandwich panel, it has controllability and applicability in more scenarios, and has great application potential in the fields of impact protection, aerospace, wearable devices, etc.

Description

Technical Field

[0001] The present invention relates to a sandwich panel structure designed to be stretchable and have a negative Poisson's ratio effect in the plane through connecting members and sandwich panels, belonging to the fields of new materials and new structures. Background Art

[0002] Since the beginning of the 21st century, metamaterials have gradually developed into an important branch of new material technologies. Metamaterials are to design the internal structure of materials so as to artificially control various properties of the materials to obtain new materials that do not exist in nature. Due to their outstanding advantages in aspects such as acoustics, optics, heat conduction, energy absorption and dissipation, metamaterials play a crucial role in aerospace, biomedicine, energy power, transportation and other fields. The development of metamaterials has received key attention from countries around the world.

[0003] Humans have used core materials for centuries. The concept of separating two "skin" materials and a low-density "core" first appeared in the 1840s to increase bending strength and reduce weight. Initially, mahogany was used as the panel and balsa wood was used as the core to make a sandwich-structured wing. Due to the poor moisture resistance, corrosion resistance and fire resistance of the balsa wood core, in order to improve the reliability of the aircraft, metal honeycomb core materials were developed, and then glass fiber-reinforced thermosetting composite honeycomb sandwich materials emerged. Composite sandwich structure materials were initially only used in departments with extremely strict weight requirements such as aviation and spacecraft. Due to the decline in the prices of carbon fiber and aromatic polyamide fiber reinforcements and the continuous increase in the varieties and quality of polyester, epoxy and thermoplastic resins, it provides favorable conditions for the research, application and development of more new varieties of sandwich composite materials. Sandwich panels are used as energy absorption devices and protective structures in many fields. However, the surfaces of traditional sandwich panels are mostly rigid, and it is difficult to have good performance in terms of controllability, deformability, flexibility and surface curvature isotropy, and it is difficult to meet the protection requirements under certain complex conditions (such as the non-Euclidean geometric surface of the protected object).

[0004] Concave honeycombs and rotating polygon structures are branches of negative Poisson's ratio materials and structures. They have special mechanical properties and undergo transverse contraction (expansion) under uniaxial compression (tension). They have more advantages than traditional materials in terms of shear bearing capacity, fracture resistance, energy absorption and indentation resistance. If the sandwich panel structure can be combined with negative Poisson's ratio materials to improve the flexibility, controllability and conformability of the sandwich panel, then this will open up new branches for the application and basic research of sandwich panels and provide some ideas for the adaptability of sandwich panel structures under complex conditions. Summary of the Invention

[0005] The object of the present invention is to break through the problem that the current sandwich panel structure can only act on the surface of flat objects. By utilizing the characteristics of the same-directionality and anti-dentability of the negative Poisson's ratio structure surface, a stretchable sandwich panel structure based on a negative Poisson's ratio rotating polygon is provided. The stretchability and bending of the sandwich panel structure are realized through the connection of connectors, so as to realize the practical application and popularization of the negative Poisson's ratio structure.

[0006] The technical solution adopted by the present invention is as follows: A stretchable sandwich panel structure based on a negative Poisson's ratio rotating polygon, the sandwich panel structure is composed of a plurality of sandwich panel units connected together in a rotating polygon manner, realizing a sandwich panel structure with in-plane negative Poisson's ratio effect that can be stretched and bent;

[0007] The sandwich panel unit is composed of a panel and a sandwich structure. The sandwich structure includes a three-dimensional concave hexagonal honeycomb, a regular hexagonal honeycomb, a concave hexagonal honeycomb and various forms that can meet the connection and deformation requirements;

[0008] The connection method of a plurality of sandwich panel units is realized by the connector through bonding, welding, riveting or integral production.

[0009] Preferably, the side length l of the panel, the length d of the connector, and the total length s of the sandwich panel structure in the sandwich panel structure satisfy the relationship: s > l > d.

[0010] Preferably, the total length s of the sandwich panel structure, the stretching angle α of the sandwich structure, the side length l of the panel, the length d of the connector, and the number of cells n included in each side of the sandwich panel structure should satisfy:

[0011]

[0012] Preferably, the stretching angle α of the sandwich structure satisfies: 0° < α < 45°.

[0013] Preferably, the sandwich structure can be stretched freely, and the Poisson's ratio of the panel completely conforms to the Poisson's ratio of the rotatable square structure, satisfying: v 12 = v 21 = -1.

[0014] Preferably, the total area S of the sandwich structure, the stretching angle α of the sandwich structure, the side length l of the panel, the length d of the connector, and the number of cells n included in each side of the sandwich structure should satisfy:

[0015]

[0016] Beneficial effects: The structure of the present invention can achieve horizontal tension with a negative Poisson's ratio effect without affecting the vertical load-bearing. Compared with ordinary sandwich panels, the proposed sandwich panel structure has significant improvements in terms of controllability, conformability, and surface curvature isotropy. These properties enable the sandwich panel structure to provide protection for complex objects such as non-Euclidean surfaces. The stretchable sandwich panel structure can open up new opportunities for the application and basic research of sandwich panels, and provide some ideas for the survivability of panel structures under complex conditions. Description of the Drawings

[0017] Figure 1a It is a top view of a stretchable sandwich panel structure based on a rotating polygon with a negative Poisson's ratio;

[0018] Figure 1b It is a perspective view of a unit with a three-dimensional concave hexagonal honeycomb as the core structure;

[0019] Figure 2 It is a perspective view of a stretchable sandwich panel structure with a regular hexagonal honeycomb as the core structure and hinges as connectors;

[0020] Figure 3 It is a perspective view of a stretchable sandwich panel structure with a concave hexagonal honeycomb as the core structure and hinges as connectors;

[0021] Figure 4 It is a perspective view of a stretchable sandwich panel structure with a three-dimensional concave hexagonal honeycomb as the core structure and an integrated direct connection;

[0022] Figure 5 It is a perspective view of a stretchable sandwich panel structure with a three-dimensional concave hexagonal honeycomb as the core structure and soft materials as connectors;

[0023] Figure 6 It is a perspective view of a stretchable sandwich panel structure with a three-dimensional concave hexagonal honeycomb as the core structure and soft materials as connectors stretched to 30°; Detailed Embodiments

[0024] The following further describes the present invention in conjunction with the detailed embodiments and the drawings:

[0025] A stretchable sandwich panel structure based on a rotating polygon with a negative Poisson's ratio, wherein the sandwich panel structure is formed by connecting multiple sandwich panel units in a rotating polygon manner to achieve a stretchable and bendable sandwich panel structure with an in-plane negative Poisson's ratio effect; the sandwich panel unit is composed of a panel and a core structure, and the core structure includes a three-dimensional concave hexagonal honeycomb, a regular hexagonal honeycomb, a concave hexagonal honeycomb, and various forms that can meet the connection and deformation requirements; the connection method of multiple sandwich panel units is realized by the connector through bonding, welding, riveting, or integrated manufacturing.

[0026] In the sandwich panel structure, the side length l of the face panel, the length d of the connecting member, and the total length s of the sandwich panel structure satisfy the relationship: s > l > d.

[0027] The total length s of the sandwich panel structure, the tensile angle α of the sandwich structure, the side length l of the face panel, the length d of the connecting member, and the number of cells n included in each side of the sandwich panel structure should satisfy:

[0028]

[0029] The tensile angle α of the sandwich structure satisfies: 0° < α < 45°.

[0030] The sandwich structure can be stretched freely, and the Poisson's ratio of the face panel exactly conforms to that of the rotatable square structure, satisfying: v 12 = v 21 = -1.

[0031] The total area S of the sandwich structure, the tensile angle α of the sandwich structure, the side length l of the face panel, the length d of the connecting member, and the number of cells n included in each side of the sandwich structure should satisfy:

[0032]

[0033] Taking the combination of 4 sandwich panel units as an example, Figure 1a is a top view of a stretchable sandwich panel structure based on a negative Poisson's ratio rotating polygon. Figure 1b is a perspective view of a unit with a three-dimensional concave hexagonal honeycomb as the sandwich structure.

[0034] Taking the combination of 9 sandwich panel units as an example, Figure 2 is a perspective view of a stretchable sandwich panel structure with a regular hexagonal honeycomb as the sandwich structure and hinges as the connecting members.

[0035] Taking the combination of 9 sandwich panel units as an example, Figure 3 is a perspective view of a stretchable sandwich panel structure with a concave hexagonal honeycomb as the sandwich structure and hinges as the connecting members.

[0036] Taking the combination of 9 sandwich panel units as an example, Figure 4 is a perspective view of a stretchable sandwich panel structure with a three-dimensional concave hexagonal honeycomb as the sandwich structure and an integrated direct connection.

[0037] Taking the combination of 9 sandwich panel units as an example, Figure 5 is a perspective view of a stretchable sandwich panel structure with a three-dimensional concave hexagonal honeycomb as the sandwich structure and soft materials as the connecting members.

[0038] Taking the combination of 9 sandwich panel units as an example, Figure 6 is a perspective view of a stretchable sandwich panel structure with a three-dimensional concave hexagonal honeycomb as the sandwich structure and soft materials as the connecting members stretched to 30°.

[0039] The above design method of a stretchable sandwich panel structure based on a negative Poisson's ratio rotating polygon includes the following steps:

[0040] 1) Select a base material according to the actual application scenario and design relevant parameters, including the total length s of the sandwich panel structure, the stretching angle α of the sandwich structure, the side length l of the panel, the length d of the connecting member, the number of cells n included in each side of the sandwich panel structure, the thickness t of the panel, and the total height h of the sandwich panel structure. Then select a reliable connection method and an appropriate sandwich structure.

[0041] 2) The designed sandwich panel structure can be fabricated by methods such as bonding, welding, riveting, and integral molding. Then, it can be combined according to different size requirements. There is no limit to the number of combinations, but the above size requirements need to be met.

[0042] 3) The selection of the structural base material of the design has a high degree of freedom, and the sandwich structure is selected based on the advantages, disadvantages, and applicable characteristics of different current sandwich structures. The connecting member can be replaced with other forms of connection, but for the stretchability of the overall structure, the variability of the connecting member is necessary, and it can be connected by means such as soft materials, hinges, bolts, and welding. The shape of the panel can also be designed to increase its practicality or aesthetics without interfering with deformation.

[0043] It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this example can be implemented by existing technologies.

Claims

1. A stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio, characterized in that: The sandwich panel structure is formed by connecting multiple sandwich panel units in a rotating polygon manner, realizing a stretchable and bendable sandwich panel structure with an in-plane negative Poisson's ratio effect; The sandwich panel unit consists of a face panel and a sandwich structure, and the sandwich structure includes a three-dimensional concave hexagonal honeycomb, a regular hexagonal honeycomb, and a concave hexagonal honeycomb; The connection method of multiple sandwich panel units is realized by the connector through bonding, welding, riveting or integral manufacturing.

2. The stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio according to claim 1, characterized in that: In the sandwich panel structure, the side length l of the face panel, the length d of the connector, and the total length s of the sandwich panel structure satisfy the relationship: s > l > d.

3. A stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio according to claim 2, characterized in that: The total length s of the sandwich panel structure, the stretching angle α of the sandwich structure, the side length l of the face panel, the length d of the connector, and the number of cells n included in each side of the sandwich panel structure should satisfy:

4. A stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio according to claim 3, characterized in that: The stretching angle α of the sandwich structure satisfies: 0° < α < 45°.

5. A stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio according to claim 4, characterized in that: The Poisson's ratio of the panel exactly conforms to that of the rotatable square structure and satisfies: v 12 = v 21 = -1.

6. The stretchable sandwich panel structure based on a rotating polygon with negative Poisson's ratio according to claim 5, characterized in that: The total area S of the sandwich structure, the stretching angle α of the sandwich structure, the side length l of the face panel, the length d of the connector, and the number of cells n included in each side of the sandwich structure should satisfy:

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