Three-dimensional double-arrow negative poisson's ratio structure and design method thereof

Abstract

The application provides a three-dimensional double-arrow negative Poisson's ratio structure and relates to the technical field of negative Poisson's ratio metamaterials. The structure is connected by a plurality of compression-torsion units, the compression-torsion unit is connected by a plurality of three-dimensional double-arrow unit cells, and the three-dimensional double-arrow unit cell is connected by two single-arrow frame bodies. The design method comprises the following steps: step one: draw a two-dimensional sketch of a single-arrow frame body on a front reference plane; step two: bidirectionally stretch the two-dimensional sketch of the single-arrow frame body by a distance t / 2, then cut a square with a side length and thickness of t at the connection between the inclined rod and the bottom rod as a connection section of the lattice structure, obtain the single-arrow frame body, then rotate the single-arrow frame body by an angle delta around an axis to obtain a three-dimensional double-arrow unit cell; step three: connect a plurality of three-dimensional double-arrow unit cells and linearly array them upwards; and step four: construct the three-dimensional double-arrow negative Poisson's ratio structure in a plane. The application has better mechanical properties and energy absorption effect.

Description

Technical Field

[0001] This invention relates to the field of energy absorption technology for mechanical negative Poisson's ratio metamaterials, and in particular to a three-dimensional double-arrow negative Poisson's ratio structure and its design method. Background Technology

[0002] With the continuous iterative development of production science, engineering technology in many fields is changing rapidly. As production methods improve, the requirements for materials science are also increasing. The application space of traditional materials is shrinking, and in some fields they can no longer meet the requirements of production technology. Therefore, it is necessary to develop metamaterials with extraordinary mechanical properties for application in engineering construction.

[0003] Negative Poisson ratio materials, as a branch of metamaterials, possess the anomalous mechanical property of contracting under compression and expanding under tension. This unique mechanical property gives negative Poisson ratio metamaterials superior specific stiffness, specific strength, shear resistance, impact resistance, and sound absorption properties compared to traditional materials. Currently, common negative Poisson ratio metamaterial structures include concave structures, chiral or antichiral structures, rigid polygonal structures, and re-entrant structures. These negative Poisson ratio metamaterials have already played a crucial role in fields such as vehicles, ships, aerospace, and medical devices.

[0004] Currently, bi-arrow negative Poisson's ratio metamaterials have seen some development, but research on three-dimensional bi-arrow negative Poisson's ratio metamaterials is limited. Most existing bi-arrow negative Poisson's ratio metamaterials lack compression-torsion properties, their negative Poisson's ratio and energy absorption effects are not significant enough, and their structural stability under load is poor. In view of the above reasons, this invention proposes a three-dimensional bi-arrow negative Poisson's ratio structure and its design method. Compared with previous bi-arrow negative Poisson's ratio metamaterials, it exhibits compression-torsion characteristics, better mechanical properties and energy absorption effects, and a wider range of Poisson's ratio adjustability, making it more universally applicable in practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a three-dimensional double-arrow negative Poisson's ratio structure and its design method. This structure has compressive and torsional characteristics, better mechanical properties and energy absorption effect, and a wider range of Poisson's ratio adjustability, making it more universal in practical applications.

[0006] On one hand, the present invention provides a three-dimensional double-arrow negative Poisson's ratio structure, which is formed by a linear array of multiple compression-torsion units connected in three-dimensional space. The compression-torsion unit is formed by a number of three-dimensional double-arrow unit cells connected in a torsional sequence. The three-dimensional double-arrow unit cell is formed by two single-arrow frames connected vertically. The top surface is integrally connected at the apex where the diagonal rods of the two single-arrow frames intersect. The bottom surface is formed by the vertical connection of the middle parts of the bottom rods of the two single-arrow frames. A connecting cross section is formed at the outer side where each diagonal rod intersects with the bottom rod. The top surface of the three-dimensional double-arrow unit cell is fixedly connected to the connecting cross section of the adjacent three-dimensional double-arrow unit cell in sequence.

[0007] Preferably, both the top surface and the bottom surface are cross-shaped planes, and the top surface and the bottom surface are parallel.

[0008] Preferably, the length and width of the cross plane are equal.

[0009] Preferably, the connecting surface is a rectangular plane, and the connecting surface is perpendicular to the top surface.

[0010] Preferably, the rectangular plane is a square.

[0011] Preferably, the top surface and the connecting cut surface are seamlessly bonded or integrally connected.

[0012] Preferably, the bottom surface is located on the side of the end connection line of the two diagonal rods near the top surface, and the two ends of the bottom surface are respectively fixedly connected to the bottom end of the diagonal rod through the bottom rod.

[0013] On the other hand, the present invention provides a design method for the above-mentioned three-dimensional double-arrow negative Poisson's ratio structure, including the following steps:

[0014] Step 1: Draw a 2D sketch of the single-arrow frame of the 3D double-arrow unit cell on the front view reference plane. The top side length is d, the length of the diagonal bar is l, the bottom side length is d, and the angle between the diagonal bar and the bottom bar is θ. Draw the centerline outline of the front view according to the above parameters. Offset the centerline outline of the front view by a bidirectional equidistant distance t / 2 to obtain the 2D sketch of the single-arrow frame.

[0015] Step 2: Twist the two-dimensional sketch of the single arrow frame by a distance of t / 2. Then, cut out a square with a side length and thickness of t at the connection between the diagonal bar and the bottom bar as the connecting surface of the lattice structure to obtain the single arrow frame. Then, rotate the single arrow frame around the axis by an angle δ in a circular array to obtain a three-dimensional double arrow unit cell.

[0016] Step 3: Arrange multiple three-dimensional double-arrow unit cells sequentially by connecting them with their top surfaces and connecting cut surfaces to obtain a single compression-torsion unit. Linearly array the single compression-torsion unit upwards, with the torsion directions of the compression-torsion units being opposite.

[0017] Step 4: By arranging the array in the horizontal and vertical directions in the plane, a three-dimensional double-arrow negative Poisson's ratio structure can be constructed.

[0018] Preferably, after offsetting the centerline outline of the front view by a bidirectional equidistant distance t / 2 in step one, the intersecting sketch lines need to be trimmed to obtain a two-dimensional sketch of the single-arrow frame.

[0019] Preferably, the rotation angle δ in step two is 90°.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The negative Poisson's ratio effect of the structure of this invention is better than that of traditional three-dimensional double-arrow negative Poisson's ratio metamaterials. It has a wider range of Poisson's ratio adjustment, better energy absorption effect, higher universality, and at the same time ensures the stability of the structure.

[0022] 2. The torsion angle of the three-dimensional double-arrow negative Poisson's ratio structure of the present invention is customizable. The torsion characteristics of the structure can be controlled by adjusting the torsion direction of the compression and torsion unit. When the compression and torsion units are all in the same upward array direction, the structure hardly twists; when the compression and torsion units are in opposite directions in the upward array, the structure twists. The torsion angle of the structure can also be changed by adjusting the geometric parameters of the three-dimensional double-arrow unit cell.

[0023] 3. The three-dimensional double-arrow negative Poisson's ratio structure of the present invention can achieve the effect of compression-torsional coupling under load, which greatly improves the energy absorption effect of the structure;

[0024] 4. By changing the length ratio of the diagonal member to the base member and the included angle between the two members, the Poisson's ratio performance of the structure can be altered;

[0025] 5. Compared with existing three-dimensional double-arrow negative Poisson's ratio metamaterials, the three-dimensional double-arrow negative Poisson's ratio structure constructed in this invention has a high degree of customization in terms of torsion angle and Poisson's ratio adjustment. While ensuring stability, it is also conducive to parametric design of negative Poisson's ratio structure. The structure design is simple and has high universality, making it easy to apply to various application scenarios.

[0026] 6. The seamless connection at the lattice joint of the three-dimensional double-arrow negative Poisson's ratio structure of this invention can improve the energy absorption effect of the structure, effectively reduce stress concentration, and improve the stability of the structure. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the three-dimensional double-arrow negative Poisson's ratio structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the two-dimensional sketch dimensions of the three-dimensional double-arrow unit cell in this invention;

[0030] Figure 3 This is a schematic diagram of the three-dimensional extrusion dimensioning of the three-dimensional double-arrow unit cell in this invention;

[0031] Figure 4 This is a schematic diagram of the structure of a single torsion unit composed of three-dimensional double-arrow unit cells in this invention;

[0032] Figure 5 This is a schematic diagram of the torsion direction after multiple torsion unit arrays are formed in this invention;

[0033] Figure 6 This is a schematic diagram of two connection methods for the torsion unit in this invention;

[0034] Figure 7 This is a top view of the three-dimensional double-arrow negative Poisson's ratio structure of the present invention, with dimension annotations.

[0035] Figure 8 This is a schematic diagram showing the front view dimensions of the three-dimensional double-arrow negative Poisson's ratio structure of the present invention;

[0036] Figure 9 This is a schematic diagram of the lattice structure of the three-dimensional double-arrow negative Poisson's ratio structure of the present invention;

[0037] Explanation of reference numerals in the attached figures:

[0038] 101: Three-dimensional double-arrow unit cell; 2: Bottom surface; 3: Base rod; 4: Diagonal rod; 5: Top surface; 6: Connecting cross section. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] like Figure 1-9 As shown, this embodiment provides a three-dimensional double-arrow negative Poisson's ratio structure, which is formed by a linear array of multiple compression-torsion units connected in three-dimensional space. The compression-torsion unit is formed by a number of three-dimensional double-arrow unit cells 101 connected in a torsional sequence.

[0043] like Figures 1-3 As shown, the three-dimensional double-arrow unit cell 101 is formed by two single-arrow frames vertically connected. The apex of the intersecting diagonal rods 4 of the two single-arrow frames is integrally connected to form the top surface 5. The middle of the bottom rods 3 of the two single-arrow frames is vertically connected to form the bottom surface 2. The outer side of the intersection of each diagonal rod 4 and the bottom rod 3 forms a connecting section 6. The top surface 5 of the three-dimensional double-arrow unit cell 101 and the connecting section 6 of the adjacent three-dimensional double-arrow unit cell 101 are seamlessly fixedly connected in sequence, realizing the closed-loop connection after twisting, thus obtaining the following... Figure 4 The pressure-torsion unit shown is obtained by stacking and connecting the pressure-torsion units one on top of the other. Figure 5 medium structure, Figure 5 The upper and lower pressure-torsion units twist in opposite directions, then... Figure 5 By arranging the medium structure in different directions within the horizontal plane, one can obtain, as shown below. Figures 6-9 The diagram shows a three-dimensional double-arrow negative Poisson ratio structure with different torsional directions and Poisson bit properties.

[0044] Specifically, both the top surface 5 and the bottom surface 2 are cross-shaped planes, with the length and width of the cross-shaped planes being equal to d, and the top and bottom surfaces are parallel. The connecting cut surface 6 is a rectangular plane; in this embodiment, the rectangular plane is a square, and the connecting cut surface 6 is perpendicular to the top surface 5. The side length of the connecting cut surface 6 is equal to the thickness t of the diagonal rod 4, and the connecting cut surface 6 and the top surface 5 are seamlessly bonded or integrally connected.

[0045] In this embodiment, the length of the diagonal rod 4 is l, the angle between the bottom end of the diagonal rod 4 and the base rod 3 is θ, the bottom surface 2 is located on the side of the end connection line of the two diagonal rods 4 near the top surface 5, and the two ends of the bottom surface 2 are fixedly connected to the bottom end of the diagonal rod 4 through the base rod 3 respectively.

[0046] This embodiment also provides a design method for the above-mentioned three-dimensional double-arrow negative Poisson's ratio structure, including the following steps:

[0047] Step 1: As Figure 2 As shown, a two-dimensional sketch of a single-arrow frame of a three-dimensional double-arrow unit cell 101 is drawn on the front view reference plane. The side length of the top surface 5 is d, the length of the diagonal rod 4 is l, the side length of the bottom surface 2 is d, and the angle between the diagonal rod 4 and the bottom rod 3 is θ. The centerline outline of the front view is drawn according to the above parameters. The centerline outline of the front view is offset by a distance t / 2 in both directions at equal intervals, and the intersecting sketch lines are trimmed to obtain a two-dimensional sketch of the single-arrow frame.

[0048] Step 2: Twist the two-dimensional sketch of the single arrow frame by a distance of t / 2, so that the thickness of the diagonal rod 4 and the bottom rod 3 is t. Then, cut out a square with a side length and thickness of t on the outside of the connection between the diagonal rod 4 and the bottom rod 3 as the connecting surface 6 of the lattice structure to obtain the single arrow frame. Then, rotate the single arrow frame around its axis by an angle δ to perform a circular array to obtain a three-dimensional double arrow unit cell.

[0049] Step 3: Connect multiple three-dimensional double-arrow unit cells using the top surface 5 and the connecting section 6 as follows: Figure 4 The order shown in the diagram can be used to obtain the desired result. Figure 4 The single compression-torsion unit in the middle, the single compression-torsion unit is... Figure 5 The structure is arranged in a linear array with the orientation of the upper part and the torsional direction of adjacent compression and torsion units are opposite, which enables the structure to torsion when subjected to external force. Furthermore, the torsion angle of the structure can be changed by adjusting the geometric parameters of the three-dimensional double-arrow unit cell.

[0050] Step 4: Array the units in the horizontal and vertical directions within the plane. The torsion directions between adjacent compression-torsion structural unit arrays can be set to be the same or opposite as required, thus constructing a structure like... Figures 6-9 Different three-dimensional double-arrow negative Poisson ratio structures.

[0051] like Figure 6As shown, the length and width of the three-dimensional double-arrow negative Poisson's ratio structure are both L (mm), as follows: Figure 7 As shown, the overall height of the three-dimensional double-arrow negative Poisson's ratio structure is H (mm); the overall width is L (mm).

[0052] In this embodiment, the construction parameters of each three-dimensional double-arrow negative Poisson's ratio structure and the three-dimensional double-arrow unit cell are as follows: the side lengths of the top surface 5 and the bottom surface 2 are d = 2 (mm); the length of the diagonal rod 4 is l = 26 (mm); the angle between the diagonal rod 4 and the bottom rod 3 is θ = 48°; the thickness of the diagonal rod 4 is t = 2 (mm); the angle between the two single-arrow frames is δ = 90°; the overall height of the three-dimensional double-arrow negative Poisson's ratio structure is H = 123.2 (mm); and the overall width of the three-dimensional double-arrow negative Poisson's ratio structure is L = 122.84 (mm).

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-dimensional double-arrow negative Poisson's ratio structure, characterized in that, The device is composed of multiple compression-torsion units connected in a linear array in three-dimensional space. Each compression-torsion unit is composed of several three-dimensional double-arrow unit cells connected in a torsional sequence. Each three-dimensional double-arrow unit cell is composed of two single-arrow frames connected vertically. The top surface is formed by the integral connection of the vertices where the diagonal rods of the two single-arrow frames intersect. The bottom surface is formed by the vertical connection of the middle parts of the bottom rods of the two single-arrow frames. A connecting cross-section is formed on the outer side of the intersection of each diagonal rod and the bottom rod. The connecting cross-section is a rectangular plane and is perpendicular to the top surface. The top surface of each three-dimensional double-arrow unit cell is fixedly connected to the connecting cross-section of the adjacent three-dimensional double-arrow unit cell in sequence. Both the top surface and the bottom surface are cross-shaped planes and are parallel to each other.

2. The three-dimensional double-arrow negative Poisson's ratio structure according to claim 1, characterized in that, The length and width of the cross plane are equal.

3. The three-dimensional double-arrow negative Poisson's ratio structure according to claim 1, characterized in that, The rectangular plane is a square.

4. The three-dimensional double-arrow negative Poisson's ratio structure according to claim 1, characterized in that, The top surface is seamlessly bonded to or integrally connected to the connecting cut surface.

5. The three-dimensional double-arrow negative Poisson's ratio structure according to claim 2, characterized in that, The bottom surface is located on the side of the connection line between the ends of the two diagonal rods, close to the top surface. The two ends of the bottom surface are respectively fixedly connected to the bottom ends of the diagonal rods through the bottom rod.

6. A design method for a three-dimensional double-arrow negative Poisson's ratio structure as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Draw a 2D sketch of the single-arrow frame of the 3D double-arrow unit cell on the front view reference plane, where the side lengths of the top and bottom faces are both 1 / 3. d The length of the diagonal bar is l The angle between the diagonal brace and the base brace is θ According to the above parameters d, l, θ Draw the centerline outline of the front view, and offset the centerline outline of the front view by an equal distance in both directions. t / 2, to obtain a two-dimensional sketch of the single-arrow frame; Step 2: Twist the 2D sketch of the single-arrow frame in both directions. t / 2, then cut a section with a side length and thickness of 1 / 2 at the connection between the diagonal bar and the base bar. t Using a square as the connecting section of the lattice structure, a single-arrow frame is obtained. Then, the single-arrow frame is rotated about the axis by an angle. δ A circular array yields a three-dimensional double-arrow unit cell; Step 3: Arrange multiple three-dimensional double-arrow unit cells sequentially by connecting them with their top surfaces and connecting cut surfaces to obtain a single compression-torsion unit. Linearly array the single compression-torsion unit upwards, with the torsion directions of the compression-torsion units being opposite. Step 4: By arranging the array in the horizontal and vertical directions in the plane, a three-dimensional double-arrow negative Poisson's ratio structure can be constructed.

7. The design method for a three-dimensional double-arrow negative Poisson's ratio structure according to claim 6, characterized in that, In step one, the centerline outline of the front view is offset bidirectionally by an equal distance. t After / 2, the intersecting sketch lines need to be trimmed to obtain a two-dimensional sketch of the single arrow frame.

8. The design method for a three-dimensional double-arrow negative Poisson's ratio structure according to claim 6, characterized in that, Rotation angle in step two δ It is 90°.

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