A method for preparing a chiral twisted negative poisson's ratio structure

Abstract

The present application relates to the field of chiral negative Poisson's ratio energy absorption structure, and discloses a preparation method of chiral compression-torsion negative Poisson's ratio structure, which can be used for the theoretical analysis of the construction of relatively complex curve profiles through Lagrange interpolation method, is beneficial to be applied to some occasions with relatively complex structure requirements, and is simple in construction mode, improves production efficiency, and changes the positive and negative Poisson's ratios of the structure in the application through the design of the oblique rod and the torsion direction of the chirality, when the torsion directions of the uppermost layer of the chiral structure of the chiral torsion columns at the four corners are opposite in turn, the structure presents negative Poisson's ratio compression, and when the torsion directions of the uppermost layer of the chiral structure of the chiral torsion columns at the four corners are the same in two directions and opposite in two directions in turn, the structure presents positive Poisson's ratio compression.

Description

TECHNICAL FIELD

[0001] The application relates to the field of chiral negative Poisson's ratio energy absorption structures, and particularly relates to a preparation method of a chiral compression-torsion negative Poisson's ratio structure. BACKGROUND

[0002] Nowadays, negative Poisson's ratio materials are increasingly used in production and life. The negative Poisson's ratio material or structure has the abnormal mechanical property of expanding in the transverse direction when being stretched and shrinking in the transverse direction when being compressed. Due to the special mechanical property, the negative Poisson's ratio material or structure has the characteristics that general materials do not have. The negative Poisson's ratio material has excellent shock absorption, good impact resistance and excellent energy absorption effect, and is widely applied to some special occasions such as vehicle traffic, aerospace, biological medicine and the like. At present, researchers have researched a plurality of negative Poisson's ratio materials with different structures, for example, reentrant structure, embedded concave structure, rotating polygonal structure, chiral structure, anti-chiral structure, origami structure and the like.

[0003] In recent years, more and more negative Poisson's ratio metamaterial structures are proposed and manufactured. The reason is that the mechanical properties of the traditional negative Poisson's ratio metamaterials have advantages and disadvantages. The stability and excellent negative Poisson's ratio effect of the structure cannot be considered. The energy absorption mode of compression-torsion coupling adopted in the application not only improves the negative Poisson's ratio effect of the structure but also has better stability than the traditional negative Poisson's ratio chiral structure. At the same time, the universality of some negative Poisson's ratio metamaterials is not good enough, which leads to the fact that the negative Poisson's ratio metamaterials cannot be simply and efficiently applied to various occasions. The negative Poisson's ratio structure proposed in the application can realize the conversion between the negative Poisson's ratio and the positive Poisson's ratio by changing the oblique rod and the torsion direction of the chirality. Such a design greatly improves the universality of the structure, reduces the manufacturing cost and realizes greater benefits. Moreover, the contact stress surface of some negative Poisson's ratio metamaterials researched at present is crushed first when being axially compressed, and then the energy is transferred to the next layer until the fixed surface. Such a process is not conducive to the energy absorption of the structure, and the negative Poisson's ratio effect of the structure is also greatly reduced. The oblique rod and the torsion direction of the chirality in the application can make the energy transfer more uniform when the structure is loaded, so that the negative Poisson's ratio effect of the whole structure is more excellent. Therefore, the application provides a preparation method of a chiral compression-torsion negative Poisson's ratio structure. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies of the prior art, the present application provides a preparation method of a chiral compression-torsion negative Poisson's ratio structure, which solves the problem that the existing research is mostly on the in-plane chiral negative Poisson's ratio energy absorption structure, while the out-of-plane chiral negative Poisson's ratio energy absorption structure is relatively less studied. In addition, in the compression-torsion coupled structure of the out-of-plane chiral negative Poisson's ratio energy absorption structure, the energy transmission effect is not good when the structure is subjected to axial compression, and most of the energy is transmitted downward to the fixed end after the contact loaded end is crushed, which presents a compression mode of layer-by-layer compression. Such compression mode is not excellent in negative Poisson's ratio effect and poor in stability during compression. In addition, the existing chiral structure is often designed by trial and error method, which increases the workload of researchers and reduces the work efficiency.

[0006] (II) Technical solutions

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a preparation method of a chiral compression-torsion negative Poisson's ratio structure, comprising the following steps:

[0008] First step: two curves with a distance of a (mm) between the upper and lower surfaces are established on the upper visual reference surface by using Lagrange interpolation method;

[0009] Second step: the two curves are connected in the first-first and tail-tail manner to form a closed surface, the normal line of the upper visual reference surface passing through the center of the closed surface is taken as a reference axis, the closed surface is circumferentially arrayed at an angle of 90 degrees around the reference axis, and the two surfaces are combined into a curved surface of the upper visual reference surface, and then the curved surface is stretched upward by a distance of b (mm) toward the reference axis to obtain a chiral structure established by using Lagrange interpolation method;

[0010] Third step: the chiral structure established by using Lagrange interpolation method is linearly arrayed upward by a distance of h (mm) for 6 times, the torsion direction of the even layers of the chiral structure established by using Lagrange interpolation method is adjusted to clockwise, one of the connecting lines of the two curves on the upper surface of the chiral structure established by using Lagrange interpolation method is translated toward the axis center by a distance of c (mm), and the obtained line, the connecting line and the two curves construct a closed plane, the same operation is performed on the lower surface of the second chiral structure established by using Lagrange interpolation method, the two closed planes are separated by an angle of 90 degrees, and the two closed planes are lofted to obtain a slant rod by placing a guide line at a certain oblique angle;

[0011] Fourth step: the slant rod is inclined in the clockwise direction around the reference axis, the slant rod is circumferentially arrayed for 4 times around the reference axis, and then the slant rod is arrayed upward for 5 times along the direction of the reference axis, the torsion direction of the even layers of the slant rod is adjusted to counterclockwise, and a single chiral torsion column is obtained.

[0012] Step 5: Next, array three individual chiral torsion columns in the negative x-axis direction and three in the positive y-axis direction. Then, keeping the individual chiral torsion column and its diagonal chiral torsion columns unchanged, reverse the torsion directions of the chiral structures and diagonal rods established by Lagrange interpolation in the other two diagonal chiral torsion columns. Then, connect the bottom layer chiral structures established by Lagrange interpolation of each chiral torsion column with connecting rods in an in-plane negative Poisson's ratio connection method. Then, array six more columns upwards along the reference axis, and rotate the connection method of the even-numbered layers of connecting rods 90 degrees around the reference axis to finally obtain a chiral torsion negative Poisson's ratio structure based on Lagrange interpolation.

[0013] Preferably, the individual chiral torsion columns at the four corners have opposite torsional directions, while the remaining chiral torsion columns have the same torsional direction.

[0014] Preferably, the torsional directions of the diagonal members in each layer of a single chiral torsion column are opposite.

[0015] Preferably, the chiral structures established by Lagrange interpolation of each layer of a single chiral torsion column have opposite torsional directions.

[0016] Preferably, the guide lines of the upper and lower plane layout bosses of the inclined rod are staggered.

[0017] The preferred curve design method based on Lagrange interpolation is as follows:

[0018] The design curve passes through n points (x1, y1)(x2, y2)(x3, y3)(x4, y4)(x5, y5)(x6, y6)......(x n ,y n If n-1 interpolation operations are required, then n-1 interpolation operations are needed. This will give us a curve that passes through the required points, where the upper curve passes through points (a1, b1); (a2, b2); (a3, b3); (a4, b4); (a5, b5); (a6, b6);

[0019] The lower curve passes through the points (c1,d1); (c2,d2); (c3,d3); (c4,d4); (c5,d5); (c6,d6).

[0020] (III) Beneficial Effects

[0021] Compared with the prior art, the present invention provides a method for preparing a chiral compression-torsion negative Poisson's ratio structure, which has the following beneficial effects:

[0022] 1. The preparation method of the chiral compression-torsion negative Poisson's ratio structure can simply and quickly analyze and construct relatively complex curve profiles through the Lagrange interpolation method, is beneficial to be applied to some occasions with relatively complex structure requirements, and the construction method is simple, thereby improving production efficiency.

[0023] 2. The preparation method of the chiral compression-torsion negative Poisson's ratio structure, the chiral structure can be adjusted and substituted according to different occasions according to the requirements of energy absorption effect or the requirements of structure space size through the Lagrange interpolation method, is beneficial to be applied to some occasions with relatively high universality requirements of structures, such as vehicles, ships, aerospace, medical devices and the like.

[0024] 3. The preparation method of the chiral compression-torsion negative Poisson's ratio structure, the torsion directions of the inclined rods are opposite, such a design can prevent the structure from being unstable when subjected to a large impact load, can make the energy transmission be more uniformly transmitted to the whole structure, and improves the overall negative Poisson's ratio effect of the structure.

[0025] 4. The preparation method of the chiral compression-torsion negative Poisson's ratio structure can change the positive and negative Poisson's ratios of the structure in the application by designing the torsion directions of the inclined rods and the chiral structure, thereby adapting to various occasions.

[0026] 5. The preparation method of the chiral compression-torsion negative Poisson's ratio structure, the connecting rods between the chiral torsion columns can realize the in-plane negative Poisson's ratio effect, and the size of the Poisson's ratio of the structure can be changed by adjusting the connection of the connecting rods of each layer. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structure schematic diagram of the chiral compression-torsion negative Poisson's ratio structure;

[0028] Figure 2 is a component part diagram of the chiral compression-torsion negative Poisson's ratio structure;

[0029] Figure 3 is an upper view torsion schematic diagram of the chiral compression-torsion negative Poisson's ratio structure;

[0030] Figure 4 is a front view of the chiral compression-torsion negative Poisson's ratio structure;

[0031] Figure 5 is a chiral structure design diagram of the chiral compression-torsion negative Poisson's ratio structure;

[0032] Figure 6 is a unit cell labeling diagram of the chiral compression-torsion negative Poisson's ratio structure.

[0033] In the figure: 1, connecting rod; 2, chiral structure established by the Lagrange interpolation method; 3, inclined rod. DETAILED DESCRIPTION

[0034] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0035] Please refer to Figures 1-6 A chiral splay negative Poisson's ratio structure, comprising the following steps:

[0036] The first step is to establish a single chiral twist column. First, a series of points are taken on the upper visual reference plane and connected smoothly to form a smooth curve by using Lagrange interpolation method. Then, a series of points are taken on the lower side of the curve at a distance a (mm) on the upper visual reference plane, and a curve is established by using Lagrange interpolation method. The middle of the two curves is thick and the two sides are thin.

[0037] The second step is to connect the two curves from the beginning to the beginning and from the end to the end to form a closed surface. The normal line of the upper visual reference plane passing through the center of the closed surface is taken as the reference axis. The closed surface is circumferentially arrayed by 90 degrees around the reference axis, and the two surfaces are combined into a curved surface of the upper visual reference plane. The curved surface is stretched upward by a distance b (mm) towards the reference axis, and a chiral structure 2 based on Lagrange interpolation method is obtained. The chiral structure 2 based on Lagrange interpolation method is linearly arrayed upward by a distance h (mm) for 6 times. The twist direction of the even layers of the chiral structure 2 based on Lagrange interpolation method is adjusted to clockwise. One of the connecting lines of the two curves on the upper surface of the chiral structure 2 based on Lagrange interpolation method is translated towards the axis by a distance c (mm), and the obtained line, the connecting line and the two curves construct a closed plane. The same operation is performed on the lower surface of the second chiral structure 2 based on Lagrange interpolation method. The two closed planes are separated by an angle of 90 degrees. The two closed planes are lofted to form a boss. The guide lines are not one-to-one corresponding but are staggered by a little. An inclined rod 3 is obtained, and the inclined rod 3 is inclined in the clockwise direction around the reference axis. The inclined rod 3 is circumferentially arrayed by 4 times around the reference axis, and is arrayed upward by 5 times along the direction of the reference axis. The twist direction of the even layers of the inclined rod 3 is adjusted to counterclockwise, and a single chiral twist column is obtained.

[0038] Step 3: Next, array three individual chiral torsion columns in the negative x-axis direction and three in the positive y-axis direction. Then, except for the individual chiral torsion column and the chiral torsion columns opposite it, reverse the torsion direction of the chiral structure and the diagonal rod in the other two chiral torsion columns at the other two corners. Then connect the bottom chiral structure of each chiral torsion column with connecting rod 1 in an in-plane negative Poisson's ratio connection method. Then, array six more columns upwards along the reference axis. Rotate the connecting rod 1 of the even-numbered layers 90 degrees around the reference axis and connect them in an in-plane negative Poisson's ratio connection method. Finally, the chiral torsion negative Poisson's ratio structure based on the Lagrange interpolation method of this invention is obtained.

[0039] like Figure 3 As shown, the chiral torsional negative Poisson's ratio structure established based on the Lagrange interpolation method has a length of L (mm) and a width of L (mm); the torsional direction of each chiral torsional column is also marked.

[0040] like Figure 4 As shown, the overall height of the chiral torsional negative Poisson's ratio structure established based on the Lagrange interpolation method is H (mm); the height of the chiral torsional unit cell is h (mm).

[0041] like Figure 5 As shown, the length of the connecting line between the two curves established by Lagrange interpolation for the chiral torsional negative Poisson's ratio structure is a (mm); the curve design method established by Lagrange interpolation in this invention is as follows:

[0042] The design curve passes through n points (x1, y1)(x2, y2)(x3, y3)(x4, y4)(x5, y5)(x6, y6)......(x n ,y n If n-1 interpolation operations are required, then n-1 interpolation operations are needed. This will give us a curve that passes through the required points, where the upper curve passes through points (a1, b1); (a2, b2); (a3, b3); (a4, b4); (a5, b5); (a6, b6);

[0043] The lower curve passes through the points (c1,d1); (c2,d2); (c3,d3); (c4,d4); (c5,d5); (c6,d6).

[0044] like Figure 6 As shown, the chiral structure thickness of the chiral torsional negative Poisson's ratio structure established based on the Lagrange interpolation method is b (mm); the distance between the two parallel lines on the lower surface of the diagonal bar is c (mm).

[0045] The case construction parameters are as follows: L = 100.53 (mm); H = 127.66 (mm); h = 27.13 (mm); a = 3 (mm); b = 2 (mm); c = 3 (mm);

[0046] (a1, b1) = (0, 0); (a2, b2) = (7.06, 3.88); (a3, b3) = (14.12, 0);

[0047] (a4, b4) = (16.94, -1.45); (a5, b5) = (19.65, -2.4); (a6, b6) = (25.19, 0)

[0048] (c1, d1) = (0, 0); (c2, d2) = (7.06, 3.14); (c3, d3) = (14.12, 0);

[0049] (c4, d4) = (16.94, -1.45); (c5, d5) = (19.65, -3.12); (c6, d6) = (25.19, 0).

[0050] While the embodiments of the application have been shown and described, it is to be understood that the embodiments can be varied, modified, substituted and otherwise changed by those skilled in the art without departing from the principles and spirit of the application, the scope of which is to be determined by the following claims and their equivalents.

Claims

1. A method of fabricating a chiral splay-negapoisson structure, characterized by, The method comprises the following steps: Step 1: two curves with a distance of a (mm) are established on the upper visual reference surface by using Lagrange interpolation method; Step 2: the two curves are connected to form a closed surface, the normal line of the upper visual reference surface passing through the center of the closed surface is taken as a reference axis, the closed surface is circumferentially arrayed by 90 degrees around the reference axis, and two surfaces are combined into a curved surface of the upper visual reference surface, and then the curved surface is stretched upward by a distance of b (mm) toward the reference axis, so as to obtain a chiral structure (2) established by using Lagrange interpolation method; Step 3: the chiral structure (2) established by using Lagrange interpolation method is linearly arrayed upward by a distance of h (mm), the twist direction of the even layers of the chiral structure (2) established by using Lagrange interpolation method is adjusted to clockwise, one connecting line of the two curves on the upper surface of the chiral structure (2) established by using Lagrange interpolation method is translated toward the axis center by a distance of c (mm), the obtained line and the connecting line and the two curves construct a closed plane, the same operation is performed on the lower surface of the second chiral structure (2) established by using Lagrange interpolation method, the two closed planes are separated by an angle of 90 degrees, the two closed planes are lofted to form a boss, guide lines are arranged at a certain oblique angle, and an inclined rod (3) is obtained; Step 4: the inclined rod (3) is inclined in the clockwise direction around the reference axis, the inclined rod (3) is circumferentially arrayed by 4 around the reference axis, and then the inclined rod (3) is arrayed upward by 5 along the direction of the reference axis, the twist direction of the even layers of the inclined rod (3) is adjusted to counterclockwise, so as to obtain a single chiral twist column; Step 5: then, the single chiral twist column is arrayed by 3 in the negative direction of the x axis and the positive direction of the y axis, the single chiral twist column and the chiral twist column opposite thereto are not changed, the twist directions of the chiral structure (2) and the inclined rod (3) of the other two chiral twist columns opposite to each other are reversed, the bottom chiral structure (2) of each chiral twist column is connected by a connecting rod (1) in a face negative Poisson's ratio connection mode, then the connecting rod (1) is arrayed upward by 6 along the direction of the reference axis, the connection mode of the connecting rod (1) of the even layers is rotated by 90 degrees around the reference axis, and finally a chiral twist negative Poisson's ratio structure based on the Lagrange interpolation method is obtained.

2. The method of claim 1, wherein: The twist directions of the single chiral twist columns at the four corners are opposite in sequence, and the twist directions of the remaining chiral twist columns are the same.

3. The method of claim 1, wherein: The twist directions of the inclined rods (3) of the layers of the single chiral twist column are opposite.

4. The method of claim 1, wherein: The twist directions of the chiral structures (2) of the layers of the single chiral twist column are opposite.

5. The method of claim 1, wherein: The guide lines of the bosses on the upper and lower planes of the inclined rod (3) are staggered and connected.

6. The method of claim 1, wherein: The curve design method based on the Lagrange interpolation method is as follows: Design a curve through n points (x1, y1) (x2, y2) (x3, y3) (x4, y4) (x5, y5) (x6, y6)... (xn, yn), then n-1 times difference n ,y n ) is needed Thus, a curve through the required points can be obtained, where the curve passes through (a1, b1); (a2, b2); (a3, b3); (a4, b4); (a5, b5); (a6, b6); The lower curve passes through points (c1, d1); (c2, d2); (c3, d3); (c4, d4); (c5, d5); (c6, d6).

Images