阅读说明：本技术 一种具有负泊松比特性的三维爪形结构及其组合方法 (Three-dimensional claw-shaped structure with negative Poisson ratio characteristic and combination method thereof ) 是由 李方义 陈修杰 于 2021-07-22 设计创作，主要内容包括：本发明涉及一种具有负泊松比特性的三维爪形结构,包括基本单元,基本单元包括三个螺旋结构单元,螺旋结构单元包括四个弧形杆、四个连接杆；四个弧形杆的一端连接至同一连接点,四个弧形杆间隔90°设置；连接杆的一端与弧形杆的另一端连接；三个螺旋结构单元中,一个螺旋结构单元水平放置,两个螺旋结构单元竖直且重合放置；水平放置的螺旋结构单元的连接点与两个竖直放置的螺旋结构单元的连接点重合；重合放置的两个螺旋结构单元中,以经过连接点的竖线为转轴,一个螺旋结构单元沿转轴相对于另一个螺旋结构单元旋转90°。本发明还涉及一种具有负泊松比特性的三维爪形结构的组合方法。本发明稳定性好,六个面都能实现负泊松比特性。(The invention relates to a three-dimensional claw-shaped structure with negative Poisson ratio characteristic, which comprises a basic unit, wherein the basic unit comprises three spiral structure units, and each spiral structure unit comprises four arc-shaped rods and four connecting rods; one ends of the four arc-shaped rods are connected to the same connecting point, and the four arc-shaped rods are arranged at intervals of 90 degrees; one end of the connecting rod is connected with the other end of the arc-shaped rod; one of the three spiral structure units is horizontally arranged, and the two spiral structure units are vertically and coincidently arranged; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically placed spiral structure units; in the two superposed helical structural units, one helical structural unit is rotated by 90 degrees relative to the other helical structural unit along a rotating shaft by taking a vertical line passing through a connecting point as the rotating shaft. The invention also relates to a combination method of the three-dimensional claw-shaped structure with the negative Poisson ratio characteristic. The invention has good stability, and the six surfaces can realize the negative Poisson ratio characteristic.)

1. A three-dimensional claw structure having a negative poisson's ratio characteristic, the three-dimensional claw structure comprising: the device comprises a plurality of basic units, wherein each basic unit comprises three spiral structure units, and each spiral structure unit comprises four arc-shaped rods and four connecting rods; one ends of the four arc-shaped rods are connected to the same connecting point, and the four arc-shaped rods are arranged at intervals of 90 degrees; one end of each of the four connecting rods is connected with the other end of each of the four arc-shaped rods, and the other end of each connecting rod extends towards the outer side of each arc-shaped rod; one of the three spiral structure units is horizontally arranged, and the two spiral structure units are vertically and coincidently arranged; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically superposed spiral structure units; in the two vertical and superposed helical structure units, a vertical line passing through a connecting point is taken as a rotating shaft, and one helical structure unit is arranged along the rotating shaft and rotates for 90 degrees relative to the other helical structure unit.

2. A three-dimensional claw structure having negative poisson's ratio characteristics as claimed in claim 1, wherein: in the plurality of basic units, every eight basic units are connected to form a cubic frame; in the cubic frame, adjacent basic units are connected through the other ends of the corresponding connecting rods;

the three-dimensional claw structure is formed by stacking a plurality of cubic frames in the horizontal direction and the vertical direction.

3. A three-dimensional claw structure having negative poisson's ratio characteristics as claimed in claim 1, wherein: the arc-shaped rod is a semicircular rod.

4. A three-dimensional claw structure having negative poisson's ratio characteristics as claimed in claim 3, wherein: the connecting rod is tangent to the arc-shaped rod.

5. A three-dimensional claw structure having negative poisson's ratio characteristics as claimed in claim 1, wherein: the cross sections of the arc-shaped rod and the connecting rod are rectangular.

6. A three-dimensional claw structure having negative poisson's ratio characteristics as claimed in claim 1, wherein: the three-dimensional claw-shaped structure is manufactured by 3D printing and integral forming.

7. A method of assembling a three-dimensional claw structure having negative Poisson's ratio characteristics according to any one of claims 1-6, wherein: the method comprises the following steps:

s1: horizontally placing one spiral structure unit, and vertically placing two spiral structure units in a superposed manner; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically superposed spiral structure units; one of the two vertically overlapped spiral structure units is arranged along the rotating shaft by rotating 90 degrees relative to the other spiral structure unit to form a basic unit;

s2: connecting eight basic units to form a cubic frame; in the cubic frame, adjacent basic units are connected through the other ends of the corresponding connecting rods;

s3: a plurality of cubic frames are stacked in the horizontal direction and the vertical direction to form a three-dimensional claw-shaped structure.

Technical Field

The invention relates to the technical field of negative Poisson ratio structures, in particular to a three-dimensional claw-shaped structure with a negative Poisson ratio characteristic and a combination method thereof.

Background

The poisson ratio is the ratio of the absolute value of transverse positive strain and axial positive strain when a material is unidirectionally pulled or pressed, and is also called a transverse deformation coefficient, and is an elastic constant reflecting transverse deformation of the material. The negative poisson's ratio effect is a phenomenon in which a material expands laterally in an elastic range when stretched, and contracts laterally in an elastic range when compressed. Compared with the traditional positive poisson ratio material (common in the natural world), the negative poisson ratio material has unique properties different from the common material, has incomparable advantages compared with other materials in many aspects, and particularly greatly improves the physical and mechanical properties of the material, such as the shear modulus, the notch resistance and the fracture resistance of the material and the resilience toughness of the material.

The problems of the existing negative Poisson ratio structure are as follows: 1. most negative Poisson ratio structures are still two-dimensional structures, energy absorption in one direction can be realized, and the energy absorption effect is common. 2. The stability and the impact resistance of the conventional negative Poisson ratio structure are poor.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention aims to: the three-dimensional claw-shaped structure with the negative Poisson ratio characteristic and the combination method thereof are good in stability, and the negative Poisson ratio characteristic can be realized on six surfaces.

In order to achieve the purpose, the invention adopts the following technical scheme:

a three-dimensional claw-shaped structure with negative Poisson ratio characteristic comprises a plurality of basic units, wherein each basic unit comprises three spiral structure units, and each spiral structure unit comprises four arc-shaped rods and four connecting rods; one ends of the four arc-shaped rods are connected to the same connecting point, and the four arc-shaped rods are arranged at intervals of 90 degrees; one end of each of the four connecting rods is connected with the other end of each of the four arc-shaped rods, and the other end of each connecting rod extends towards the outer side of each arc-shaped rod; one of the three spiral structure units is horizontally arranged, and the two spiral structure units are vertically and coincidently arranged; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically superposed spiral structure units; in the two vertical and superposed helical structure units, a vertical line passing through a connecting point is taken as a rotating shaft, and one helical structure unit is arranged along the rotating shaft and rotates for 90 degrees relative to the other helical structure unit.

Preferably, every eight basic units in the plurality of basic units are connected to form a cubic frame; in the cubic frame, adjacent basic units are connected through the other ends of the corresponding connecting rods; the three-dimensional claw structure is formed by stacking a plurality of cubic frames in the horizontal direction and the vertical direction.

Preferably, the connecting rod is tangent to the curved rod.

Preferably, the curved bars are semi-circular bars.

Preferably, the arc-shaped rods and the connecting rods are rectangular in cross section.

Preferably, the three-dimensional claw-shaped structure is integrally formed by 3D printing.

A method of assembling a three-dimensional claw structure having negative poisson's ratio characteristics, comprising the steps of: s1: horizontally placing one spiral structure unit, and vertically placing two spiral structure units in a superposed manner; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically superposed spiral structure units; one of the two vertically overlapped spiral structure units is arranged along the rotating shaft by rotating 90 degrees relative to the other spiral structure unit to form a basic unit; s2: connecting eight basic units to form a cubic frame; in the cubic frame, adjacent basic units are connected through the other ends of the corresponding connecting rods; s3: a plurality of cubic frames are stacked in the horizontal direction and the vertical direction to form a three-dimensional claw-shaped structure.

In summary, the present invention has the following advantages:

1. six surfaces of the three-dimensional claw-shaped structure can realize the negative Poisson ratio characteristic; when the base unit is loaded, the compression cross section of a single base unit is reduced, and when each base unit is subjected to inward rotation of the rod piece, the connecting rods between the base units are mutually acted and pulled. The integral structure has the characteristics of arbitrary surface compression in space and synchronous contraction of four adjacent side surfaces, and six surfaces in three directions can realize the characteristics of negative poisson ratio.

2. The invention has good stability and strong shock resistance; the basic unit is formed by overlapping two-two orthogonal parts of the three spiral structure units, the rotation inertia after the loaded deformation can be improved by two-two orthogonal parts between the three arc-shaped rods, the stability during impact can also be improved, and the loaded deformation process of the three-dimensional claw-shaped structure is stable. The plurality of basic units are symmetrical pairwise, and the design ensures that the four side surfaces adjacent to the loaded plane can contract inwards and narrow synchronously in the compression deformation process of the basic units, so that the negative Poisson's ratio characteristic of the three-dimensional claw-shaped structure is more obvious, and the possibility of shear deformation and crushing of the three-dimensional claw-shaped structure under higher pressure is reduced.

3. The invention is convenient to manufacture; the thickness and the height of the arc-shaped rod and the connecting rod are both t (mm). On one hand, the structure can obtain the same identity in multiple directions by the design, the manufacture is more convenient, and the efficiency of the three-dimensional claw-shaped structure is greatly improved.

4. The three-dimensional claw-shaped structure obtained by the combination method has the multidirectional negative Poisson ratio characteristic, the combination method of the invention is that the end faces of the connecting rods among a plurality of basic units are fixedly connected with each other and are stacked in the horizontal direction and the vertical direction to form the three-dimensional claw-shaped structure; the sizes of all the spiral structure units are the same, so that the basic units in each section can be synchronously deformed in the impact process, the transverse stability and the energy absorption efficiency are improved, and the stability of the impact process is improved; and four side surfaces adjacent to the loaded plane can synchronously contract inwards in the loaded deformation process, so that the bearing plate has larger section density and better bearing capacity and energy absorption effect.

5. The invention has wide application; the structure of the invention is hollow, the compression stroke is long, and the invention is suitable for wide application and various related fields.

Drawings

Fig. 1 is a perspective view of a base unit.

Fig. 2 is an exploded view of the base unit.

Fig. 3 is a perspective view of the spiral structure unit.

FIG. 4 is a schematic view of a helical structural unit.

Fig. 5 is a perspective view of a cubic frame.

Fig. 6 is a top view of a cubic frame.

Fig. 7 is a perspective view of a three-dimensional claw structure.

Fig. 8 is a top view of a three-dimensional claw structure.

Fig. 9 is a strain cloud chart of the strain value of the three-dimensional claw-shaped structure under the load as 0.

FIG. 10 is a strain cloud graph of a three-dimensional claw structure under a load with a strain value of 0.1.

FIG. 11 is a strain cloud graph of a three-dimensional claw structure under a load with a strain value of 0.2.

Fig. 12 is a strain cloud graph of the strain value of the three-dimensional claw-shaped structure under the load of 0.4.

Fig. 13 is a strain cloud graph of the strain value of the three-dimensional claw-shaped structure under the load of 0.6.

FIG. 14 is a strain cloud graph of a three-dimensional claw structure under load with a strain value of 0.7.

Wherein, 1 is the helical structure unit, 2 is the arc pole, 3 is the connecting rod, 4 is the basic unit, 5 is the cube frame, 6 is the pivot.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments.

A three-dimensional claw-shaped structure with negative Poisson ratio characteristic comprises a plurality of basic units, wherein each basic unit comprises three spiral structure units, and each spiral structure unit comprises four arc-shaped rods and four connecting rods; one ends of the four arc-shaped rods are connected to the same connecting point, and the four arc-shaped rods are arranged at intervals of 90 degrees; one end of each of the four connecting rods is connected with the other end of each of the four arc-shaped rods, and the other end of each connecting rod extends towards the outer side of each arc-shaped rod; one of the three spiral structure units is horizontally arranged, and the two spiral structure units are vertically and coincidently arranged; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically superposed spiral structure units; in the two vertical and superposed helical structure units, a vertical line passing through a connecting point is taken as a rotating shaft, and one helical structure unit is arranged along the rotating shaft and rotates for 90 degrees relative to the other helical structure unit.

In the plurality of basic units, every eight basic units are connected to form a cubic frame; in the cubic frame, adjacent basic units are connected through the other ends of the corresponding connecting rods; the three-dimensional claw structure is formed by stacking a plurality of cubic frames in the horizontal direction and the vertical direction.

The connecting rod is tangent to the arc-shaped rod.

The arc-shaped rod is a semicircular rod.

The cross sections of the arc-shaped rod and the connecting rod are rectangular. The connecting rod is a square straight rod.

The three-dimensional claw-shaped structure is manufactured by 3D printing and integral forming.

In this embodiment, the three-dimensional claw structure is a honeycomb structure.

A method of assembling a three-dimensional claw structure having negative poisson's ratio characteristics, comprising the steps of: s1: horizontally placing one spiral structure unit, and vertically placing two spiral structure units in a superposed manner; the connecting point of the horizontally placed spiral structure unit is superposed with the connecting points of the two vertically superposed spiral structure units; one of the two vertically overlapped spiral structure units is arranged along the rotating shaft by rotating 90 degrees relative to the other spiral structure unit to form a basic unit; s2: connecting eight basic units to form a cubic frame; in the cubic frame, adjacent basic units are connected through the other ends of the corresponding connecting rods; s3: a plurality of cubic frames are stacked in the horizontal direction and the vertical direction to form a three-dimensional claw-shaped structure.

The cubic frame comprises eight basic units; the basic unit comprises three spiral structure units, and each spiral structure unit comprises four arc-shaped rods and four connecting rods.

Composition of helical structural units: one ends of the four arc-shaped rods are connected to the same connecting point, the four arc-shaped rods are overlapped in the initial state, the first arc-shaped rod is fixed, the second arc-shaped rod rotates for 90 degrees by taking the connecting point as a rotating point, the third arc-shaped rod rotates for 180 degrees by taking the connecting point as a rotating point, the third arc-shaped rod rotates for 270 degrees by taking the connecting point as a rotating point, and two adjacent arc-shaped rods are spaced for 90 degrees; the four arc-shaped rods are spiral on the plane; the arc-shaped rod is a semi-circular arc-shaped rod with the radius of r; a rectangular coordinate system is constructed by using connection points, and the four arc-shaped rods are respectively positioned in four quadrants of the rectangular coordinate system, wherein the two arc-shaped rods of the first quadrant and the third quadrant are connected to form an S-shaped structure, and the two arc-shaped rods of the second quadrant and the fourth quadrant are connected to form an S-shaped structure; one end of each of the four connecting rods is connected with the other end of each of the four arc-shaped rods respectively, the connecting rods are tangent to the arc-shaped rods, and the connecting rods extend outwards.

Composition of the basic unit: among the three helical structure unit, a helical structure unit level is placed, and two helical structure units are vertical to be placed, and two vertical helical structure unit coincidences of placing are placed, and the helical structure unit's that the level was placed the tie point with two helical structure unit's that the coincidence was placed tie point coincidence, and in two helical structure units that the coincidence was placed to the vertical line through the tie point was the pivot, a helical structure unit was rotatory 90 for another helical structure unit along the pivot.

Composition of cubic framework: the device is formed by connecting eight basic units, wherein the eight basic units are distributed according to a cubic frame, and four basic units at the top end of the cubic frame are vertically symmetrical with four units at the bottom end of the cubic frame; and the adjacent basic units are connected with the corresponding connecting rod of the other basic unit through the connecting rod extending outwards.

Composition of the three-dimensional claw structure: formed by stacking a plurality of cubic frames in the horizontal direction and the vertical direction; wherein the connecting rods extending outwards through the basic unit of each plane are connected with the corresponding connecting rods of the other cubic frame.

As shown in fig. 2, the radius of the arc-shaped rods of the spiral structure unit is r (mm), and the lengths of the four connecting rods are all L (mm); the angle formed by the connecting rod tangent to the arc rod and the axis is phi (DEG); wherein phi is more than 0 and less than or equal to 90 degrees, the smaller the angle of phi is, the weaker the degree of inward rotation of the compression of the basic unit is, and the worse the negative poisson ratio characteristic is.

The middle line of the unit is respectively biased to the inside and the outside by t/2(mm) through modeling software, the stretching height is t (mm), the spiral structure unit can be obtained, and in order to facilitate the arrangement and combination between the basic units, the intersection of the connecting rod and the arc-shaped rod is set to be a straight edge with the length t (mm).

As shown in fig. 9, in the finite element software ABAQUS, a corresponding model was established for dynamic compression simulation, and the upper surface was set as a loaded surface and the lower bottom surface was fixed. Constructing a three-dimensional claw-shaped structure in modeling software, and enabling the initial construction parameters to be as follows: r is 4mm, phi is 90 DEG, and t is 1 mm; the given material is ABS, a compression test is carried out on the three-dimensional claw-shaped structure model by adopting finite element analysis software, the phenomenon that the three-dimensional claw-shaped structure model contracts inwards in the transverse direction is obvious in the deformation process, and the deformation is carried out synchronously; therefore, the three-dimensional claw-shaped structure model has the negative Poisson ratio characteristic in two directions perpendicular to the loaded direction, and in the compression process of the three-dimensional claw-shaped structure, the peripheral connecting rods extrude and push the arc-shaped rods in the cubic frame to rotate inwards, so that the internal fixedly-connected connecting rods are mutually pulled, and the basic units show the negative Poisson ratio characteristic that the basic units shrink inwards under pressure in multiple directions and the cross sections narrow; this motion characteristic is transferred in turn so that the three-dimensional claw structure also has the same negative poisson's ratio characteristic as the basic unit. In the three-dimensional claw-shaped structure, the basic unit has the multi-direction negative Poisson ratio characteristic, and the whole body also has the multi-direction negative Poisson ratio characteristic, so that the negative Poisson ratio characteristic can be better utilized to be applied to the field of automobile safety equipment, wearing equipment (skin-like) parts, sound insulation materials and sandwich plates.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.