WO2021062954A1 - Multifunctional fastener having multiple negative poisson's ratio effects and design method therefor - Google Patents

Abstract

A multifunctional fastener having multiple negative Poisson's ratio effects, comprising a fastener top (1), a fastener circular tube part (2), and a fastener tail (3). The fastener top (1) is a plurality of evenly distributed arc-shaped concave structures having negative Poisson' ratios. The distance from the outermost side of each arc-shaped concave angle to the outer side of a circular tube is (D3-D2)/2, and the relation between the distance and the outer diameter of the circular tube meets that: D2/20 ≤ (D3-D2)/2 ≤ D2/8, and 2 mm ≤ (D3-D2)/2. Each arc-shaped concave angle θ ranges from 50° to 70°. The number N1 of arc-shaped concave rod members on the fastener top (1) meets that: 9 ≤ N1 ≤ 25. The fastener circular tube part (2) is formed by combining an external circular tube having a negative Poisson's ratio and a support structure having a negative Poisson's ratio. The number N2 of units having negative Poisson's ratios of the external circular tube in the circumferential direction should meet that: N2 ≥ 6, and N2 is an even number. Such a fastener has good fixing and anti-loosening effects. Also provided is a design method for the multifunctional fastener having multiple negative Poisson's ratio effects.

Description

Multifunctional fastener with multiple negative Poisson's ratio effects and design method thereof Technical field

The present invention relates to a fastener with multiple negative Poisson's ratios on the head and tubular part generated by using a negative Poisson's ratio structure, and proposes a design method for the fastener with multiple negative Poisson's ratio effects, which belongs to The field of new materials and new structures.

Background technique

Poisson's ratio, also known as the transverse deformation coefficient, is a parameter that characterizes the transverse deformation of a material when it is stressed in the axial direction. Common materials in life all have a positive Poisson's ratio, that is, they expand laterally under compression and contract laterally under tension. The material with negative Poisson's ratio is the opposite. It shrinks laterally when compressed and expands laterally when tensioned. Therefore, negative Poisson's ratio materials are also called auxetic materials. Negative Poisson's ratio materials are better than traditional positive Poisson's ratio materials in certain mechanical properties, such as shear resistance, fracture resistance, energy absorption capacity, and sag resistance. Therefore, negative Poisson's ratio materials have very broad application prospects, especially when combined with traditional industrial design, it is helpful to bring about industrial design and industrial innovation.

Negative Poisson's ratio materials often have porous microstructures and require higher manufacturing precision. Traditional manufacturing technology is difficult to achieve its accuracy and complexity. And 3D printing technology, also known as additive manufacturing technology, gets rid of the limitation of traditional manufacturing technology on the production process of complex structures, and can print various materials with complex and changeable shapes. Therefore, it is of practical significance to combine the complex and changeable multiple negative Poisson's ratio structure with advanced 3D printing technology to produce negative Poisson's ratio industrial products with practical application value.

According to the application, the present invention performs a combined design on the negative Poisson's ratio structure of each component of the fastener, and introduces the 3D printing manufacturing process into the manufacture of complex and changeable negative Poisson's ratio fasteners, which can realize complex fastening Integral molding of pieces. Due to the design of the concave angle of the head, the head will shrink as a whole when it is pushed in, so that the tip part can be easily pushed in; and when it is pulled out, the resistance of the head and the friction caused by the expansion and deformation of the tubular part The force effectively prevents the fastener from sliding outward. Therefore, the fastener has the advantages of reasonable structural design, convenient manufacture, light and beautiful appearance, and material saving, which has important engineering significance and certain application value.

Summary of the invention

In order to improve the design of existing fasteners, the purpose of the present invention is to propose an integrated fastener with reasonable structural design, easier to push in, more difficult to pull out, better anti-loosening effect, lower manufacturing cost, lighter and more beautiful Its design method.

The technical scheme adopted by the present invention is: a multifunctional fastener with multiple negative Poisson's ratio effects, including the top of the fastener, the round tube part of the fastener, and the tail of the fastener;

The top of the fastener is provided with a number of evenly distributed negative Poisson's ratio arc-shaped concave structures, which can ensure that the head can be contracted evenly in the lateral direction when the head is squeezed, so that the fastener can be easily pushed in;

The distance between the outermost angle of each arc and the neutral axis is D ₃ , the outer diameter of the tube is D ₂ , and the distance between the outermost angle of each arc and the outer side of the tube is (D ₃ -D ₂ )/2, the relationship between it and the outer diameter of the tube part satisfies: D ₂ /20≤(D ₃ -D ₂ )/2≤D ₂ /8, and 2mm≤(D ₃ -D ₂ )/2; top distribution The arc structure of the formula ensures the negative Poisson ratio of the head, and the range of the concave angle θ of each arc is 50°～70°;

_{The number N 1 of the} arc-shaped concave rods on the top of the fastener satisfies: 9≤N ₁ ≤25;

The round pipe part of the fastener is formed by a combination of an outer pipe with a negative Poisson's ratio and a support structure with a negative Poisson's ratio. When subjected to an axial force, the tubular structure and the supporting structure will expand and compress, and the pipe and the supporting structure Combined deformation will occur, resulting in huge negative Poisson's ratio; in order to ensure the overall deformation and uniformity of deformation, the number of negative Poisson's ratio units N _{2 of} the outer tube along the circumferential direction should satisfy: N ₂ ≥ 6 and N ₂ Is even

In order to make the support and the outer circular tube deform in coordination without affecting the overall deformation of the outer circular tube, the supporting structure should be combined with the joints of adjacent units of the circular tube along the circumferential direction. _{The relationship between the number N 2 of} negative Poisson's ratio units in the outer tube along the circumferential direction and the angle α between adjacent units in the support structure satisfies: α=360°/N ₂ ;

To ensure the rigidity and deformation characteristics of the tube portion, the outer tube and the thickness D of the support structure _{2/2-R 1} should _{satisfy: D 2 / 16≤D 2/2} -R 1 ≤D 2/8, R ₁ is the inner diameter of the round tube;

The relationship between the _{length L 1 of the} top of the fastener _{and the length L 2 of the} round pipe part of the fastener _{satisfies: 0.8≤L 2} /L ₁ ≤2.5;

The relationship between the _{diameter D 1} of the functional part of the fastener tail _{and the outer diameter D 2} of the round pipe part of the fastener _{satisfies: 1.1≤D 1} /D ₂ ;

The relationship between the functional part diameter D ₁ of the fastener tail and the functional part length L ₃ of the fastener tail satisfies: 3.5≦D ₁ /L ₃ ≦10.3.

Preferably, the negative Poisson's ratio structure of the outer tube and the inner support can be replaced, and the negative Poisson's ratio structure of the outer tube and the support structure can be a concave hexagon, a concave triangle, a chiral structure, or a rotating polygon. Structure and other negative Poisson's ratio structure.

Preferably, the functional part of the fastener tail can be designed as a disc, a hook shape, a bayonet shape, a groove shape, etc. according to the specific purpose of the fastener.

The inner concave rod of the fastener of the present invention will expand after entering the preset hole. When the fastener is pulled, the outermost inner corner of the top will expand to the outside of the hole, and it will hinder the fastener when it is pulled. Pulling out, while the tubular structure is stretched and expanded to further increase the friction with the hole, making it difficult for the fastener to be pulled out.

The above-mentioned design method of a multifunctional fastener with multiple negative Poisson's ratio effects includes the following steps:

1) Determine the basic size of the top of the fastener according to the purpose of the fastener and the size of the push hole, including the concave angle of the top of the fastener, the number and angle of the concave structure distribution;

2) Design the length of the round pipe part of the fastener and the outer diameter of the round pipe according to the requirements of use;

3) According to the determined size, the detailed size combination design and optimization of the fastener top and the fastener tube part are carried out to ensure the deformation characteristics, negative Poisson ratio and sufficient strength of the fastener;

4) Then design the functional part of the fastener tail according to the use requirements of the fastener;

5) Using 3D printing technology to produce fasteners with multiple negative Poisson's ratio effects.

The beneficial effects of the present invention: the fastener designed by the method has a large negative Poisson's ratio effect and can simultaneously exhibit a negative Poisson's ratio effect under axial compression and tension. The negative Poisson's ratio design of the head not only makes it easy to push the fastener into the hole, and the enlarged concave angle after entering the hole is larger than the preset cavity, which can well hinder the extraction and natural loosening of the fastener, and The double negative Poisson's ratio structure of the tubular part expands when it is tensioned and further hinders the extraction of the fastener. The functional design part of the tail can be designed differently according to the purpose of the fastener, which ensures the diversity of its functions. In addition, the fastener designed by this method has a reasonable structure, is beautiful and portable, saves materials, and is integrally formed, and has good practical application value and scientific significance.

Description of the drawings

Figure 1 is a schematic diagram of the fastener structure with multiple negative Poisson's ratio effects;

Fig. 2 is a side view of Fig. 1.

Figure 3 Schematic diagram of a single arc structure at the top of the fastener;

Figure 4 is a structural diagram of the double negative Poisson's ratio of the tubular part of the fastener;

Figure 5 is a schematic diagram of the outer tube structure of the fastener.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments and drawings:

As shown in Figure 1-5, a multifunctional fastener with multiple negative Poisson's ratio effects includes a fastener top 1, a fastener tube portion 2 and a fastener tail 3;

The top 1 of the fastener is a plurality of evenly distributed negative Poisson's ratio arc-shaped concave structures; the distance between the outermost side of each arc-shaped concave angle and the neutral axis is D ₃ , and the outer diameter of the circular tube part is D ₂ , The distance between the outermost side of the inner concave angle of each arc and the outer side of the circular tube is (D ₃ -D ₂ )/2, and its relationship with the outer diameter of the circular tube satisfies: D ₂ /20≤(D ₃ -D ₂ ) /2≤D ₂ /8, and 2mm≤(D ₃ -D ₂ )/2; the range of the concave angle θ of each arc is 50°～70°;

The number of the fastener concave arcuate top bar 1 N satisfies _1: 9≤N ₁ ≤25;

The fastener tube part 2 is formed by a combination of an outer tube with a negative Poisson's ratio and a support structure with a negative Poisson's ratio. The number of negative Poisson's ratio units N _{2 of} the outer tube in the circumferential direction should satisfy: N ₂ ≥ 6 and N ₂ is an even number;

_{The relationship between the number N 2 of} negative Poisson's ratio units in the outer tube along the circumferential direction and the angle α between adjacent units in the support structure satisfies: α=360°/N ₂ ;

The thickness D of the outer tube and the support structure _{2/2-R 1} should _{satisfy: D 2 / 16≤D 2/2} -R 1 ≤D 2/8, R 1 is an inner diameter tube portion;

The relationship between the _{length L 1 of the} top 1 of the fastener _{and the length L 2 of the} round tube part 2 of the fastener _{satisfies: 0.8≤L 2} /L ₁ ≤2.5;

The relationship between the functional part diameter D _{1 of} the fastener tail 3 and the outer diameter D _{2 of the fastener tube part 2 satisfies: 1.1≤D 1} /D ₂ ;

The relationship between the functional part diameter D ₁ of the fastener tail 3 and the functional part length L ₃ of the fastener tail 3 satisfies: 3.5≦D ₁ /L ₃ ≦10.3.

The negative Poisson's ratio structure of the outer circular tube and the supporting structure is a concave hexagon, a concave triangle, a chiral structure or a rotating polygon structure. The functional part of the fastener tail 3 is designed in the shape of a disc, a hook shape, a bayonet shape or a groove shape.

The design method of the multifunctional fastener with multiple negative Poisson's ratio effects includes the following steps:

1) Determine the basic size of the top of the fastener according to the purpose of the fastener and the size of the push hole, including the concave angle of the top of the fastener, the number and angle of the concave structure distribution;

2) Design the length of the round pipe part of the fastener and the outer diameter of the round pipe according to the requirements of use;

3) According to the determined size, the detailed size combination design and optimization of the fastener top and the fastener tube part are carried out to ensure the deformation characteristics, negative Poisson ratio and sufficient strength of the fastener;

4) Then design the functional part of the fastener tail according to the use requirements of the fastener;

5) Using 3D printing technology to produce fasteners with multiple negative Poisson's ratio effects.

The key of the present invention to produce the characteristics of easy push-in and pull-out resistance lies in the design of the multiple negative Poisson's ratio structure of the top of the fastener and the rod. The concave negative Poisson’s ratio arc structure on the top and the distributed structure feature make the top of the fastener undergo a large overall contraction when axially compressed, so that the fastener is easy to push in; and the tubular part is easily pushed in by the outside. The double negative Poisson's ratio system formed by the combination with internal support, under the condition of ensuring the strength of the fastener, expansion occurs during tension to prevent the fastener from being pulled out, and the fastener can be deformed in a very large range The negative Poisson ratio is maintained within.

In addition, it should be noted that for those of ordinary skill in the art, several improvements and modifications can be made without departing from the principle of the present invention. All equivalent or simple changes made in accordance with the principles described in the concept of the patent of the present invention are included in the protection scope of the patent of the present invention. All the components that are not clear in this embodiment can be implemented using existing technology.

Claims (4)

1. A multifunctional fastener with multiple negative Poisson's ratio effects, which is characterized in that it comprises a fastener top, a fastener tube part and a fastener tail;

   The top of the fastener has a number of evenly distributed arc-shaped concave structures with negative Poisson’s ratio; the distance between the outermost side of each arc-shaped concave angle and the neutral axis is D ₃ , and the outer diameter of the circular tube part is D ₂ , The distance between the outermost side of the inner concave angle of each arc and the outer side of the round tube is (D ₃ -D ₂ )/2, and its relationship with the outer diameter of the round tube satisfies: D ₂ /20≤(D ₃ -D ₂ )/ 2≤D ₂ /8, and 2mm≤(D ₃ -D ₂ )/2; the range of the concave angle θ of each arc is 50°～70°;

   _{The number N 1 of the} arc-shaped concave rods on the top of the fastener satisfies: 9≤N ₁ ≤25;

   The fastener tube part is formed by a combination of an outer tube with a negative Poisson's ratio and a support structure with a negative Poisson's ratio. The number of negative Poisson's ratio units N _{2 of} the outer tube in the circumferential direction should satisfy: N ₂ ≥6 and N ₂ is an even number;

   _{The relationship between the number N 2 of} negative Poisson's ratio units in the outer tube along the circumferential direction and the angle α between adjacent units in the support structure satisfies: α=360°/N ₂ ;

   The thickness D of the outer tube and the support structure _{2/2-R 1} should _{satisfy: D 2 / 16≤D 2/2} -R 1 ≤D 2/8, R 1 is an inner diameter tube portion;

   The relationship between the _{length L 1 of the} top of the fastener _{and the length L 2 of the} round pipe part of the fastener _{satisfies: 0.8≤L 2} /L ₁ ≤2.5;

   The relationship between the _{diameter D 1} of the functional part of the fastener tail _{and the outer diameter D 2} of the round pipe part of the fastener _{satisfies: 1.1≤D 1} /D ₂ ;

   The relationship between the functional part diameter D ₁ of the fastener tail and the functional part length L ₃ of the fastener tail satisfies: 3.5≦D ₁ /L ₃ ≦10.3.
2. The multifunctional fastener with multiple negative Poisson's ratio effects according to claim 1, wherein the negative Poisson's ratio structure of the outer tube and the supporting structure is a concave hexagon or a concave triangle. , Chiral structure or rotating polygon structure.
3. The multifunctional fastener with multiple negative Poisson's ratio effects according to claim 1, wherein the functional part of the fastener tail is designed as a disc, a hook shape, a bayonet shape or a groove shape.
4. A design method of a multifunctional fastener with multiple negative Poisson's ratio effects according to claim 1, 2 or 3, characterized in that it comprises the following steps:

   1) Determine the basic size of the top of the fastener according to the purpose of the fastener and the size of the push hole, including the concave angle of the top of the fastener, the number and angle of the concave structure distribution;

   2) Design the length of the round pipe part of the fastener and the outer diameter of the round pipe according to the requirements of use;

   3) According to the determined size, design and optimize the detailed size combination of the top of the fastener and the round pipe part of the fastener to ensure the deformation characteristics, negative Poisson ratio and sufficient strength of the fastener;

   4) Then design the functional part of the fastener tail according to the use requirements of the fastener;

   5) Using 3D printing technology to produce fasteners with multiple negative Poisson's ratio effects.

Images