A spring metamaterial and a compression-expansion-tension body

Abstract

The present invention relates to the field of elastic materials and discloses a spring metamaterial having an initial Poisson's ratio. v 0 and initial helix angle i 0 The following formula is satisfied: #imgabs0#; When the initial helical angle is #imgabs1#, the spring metamaterial undergoes a large deformation within the effective travel range after being subjected to force, and the volume of the space occupied by it decreases when subjected to tension, and the volume of the space occupied by it increases first and then decreases when subjected to pressure; Initial Poisson's ratio v 0 >0.5, elastic modulus E The rate of change is less than 5%; the Poisson's ratio of the spring metamaterial v The volume ratio and the stretching ratio are nonlinearly related. A compression-expansion-tensile body comprises a spring body metamaterial and an elastic outer coat wrapped around the spring body metamaterial. The compression-expansion-tensile body has the same physical properties as the spring body metamaterial. The compression-expansion-tensile body is applied in the sealing field and has the effects of high durability, simple installation and operation, and good sealing.

Description

Technical Field

[0001] The invention relates to the field of elastic materials, in particular to a spring metamaterial and a compression-expansion-tension body. Background Art

[0002] Metamaterials refer to artificial composite structures or composite materials with extraordinary physical properties that natural materials do not possess. There is nothing special about the composition of these materials. Their unique properties come from the geometric structure and size of the materials. After artificial design, metamaterials can have special physical properties that natural materials do not have. Normally, the volume of elastomers will decrease when subjected to pressure and will expand when subjected to tension, while the volume of plastics remains unchanged when subjected to pressure or tension. Therefore, the bulk modulus of conventional substances is not less than zero, and the Poisson's ratio is not greater than 0.5.

[0003] There are many elastomeric metamaterials in the prior art, such as application number CN102810752B, which discloses a metamaterial and a metamaterial antenna, wherein the metamaterial is relatively arranged in the electromagnetic wave propagation direction of the radiation source; the angle between the line connecting the radiation source and a point on the first surface of the metamaterial and the straight line perpendicular to the metamaterial is θ, the angle θ uniquely corresponds to a curved surface in the metamaterial, and the refractive index at each point on the curved surface uniquely corresponding to the angle θ is the same, and the generatrix of the curved surface is a parabolic arc; the refractive index of the metamaterial gradually decreases as the angle θ increases; the electromagnetic wave is emitted in parallel at the top surface of each torus after passing through the metamaterial; by designing the jump of the refractive index of the metamaterial to be a curved surface, the refraction, diffraction and reflection effects at the jump are greatly reduced, and the problems caused by mutual interference are alleviated, so that the metamaterial and the metamaterial antenna have more excellent performance.

[0004] The inventors found that when conventional elastomers are used in the field of sealing, they are usually compressed into the gap of the device to be sealed within their compressible volume range. Since the volume of conventional elastomers shrinks when they are under pressure, we can use this property to stuff the elastomer into the gap under the action of external force to achieve a sealing effect. However, this conventional material is always under stress during the application process, and conventional materials will slowly age over time. After aging, conventional materials are extremely susceptible to damage under the action of force, and their durability is reduced. In addition, their durability will be further reduced after external forces such as mechanical vibration and mechanical friction. At the same time, in the sealing process, we usually use the characteristic that elastomers can deform after being subjected to force to perform sealing, but this sealing method requires external force to be applied during the installation process, and the installation operation is also more complicated. Therefore, the present application designs a metamaterial to address the above-mentioned problems and explores the application of metamaterials. Summary of the invention

[0005] In order to solve the problems of low durability and complicated application operation of conventional elastomers in the prior art, the present application provides a spring body metamaterial and a compression-expansion-tensile body. The spring body metamaterial has the special physical property of undergoing a large deformation within an effective stroke range after being subjected to force, and the volume of the space occupied by it decreases when subjected to tension, and the volume of the space occupied by it first increases and then decreases when subjected to pressure. The compression-expansion-tensile body is composed of a spring body metamaterial and an elastic outer skin. The compression-expansion-tensile body has the same physical properties as the spring body metamaterial. When applied in the sealing field, it can achieve the technical effects of high durability and simple application operation.

[0006] The specific technical scheme of the present invention is:

[0007] A spring metamaterial, wherein the initial helical angle of the spring metamaterial is θ0, the initial Poisson's ratio is v0, the Poisson's ratio is v, the volume elastic modulus is E, the volume modulus is K, the stretching ratio is λx, and the initial Poisson's ratio v0 and the initial helical angle θ0 satisfy the following formula: v0=tan 2 θ0; the initial helix angle When the spring-body metamaterial is subjected to force, a large deformation occurs within the effective stroke range. When subjected to tension, the space volume occupied by the spring-body metamaterial decreases, and when subjected to pressure, the space volume occupied by the spring-body metamaterial first increases and then decreases. The initial Poisson's ratio v0 is greater than 0.5, and the rate of change of the elastic modulus E is less than 5%. The Poisson's ratio v and volume ratio of the spring-body metamaterial are respectively nonlinearly related to the stretching ratio.

[0008] The present application provides a spring metamaterial, which has the physical property of expanding volume when subjected to force; the applicant designs the structure of the spring body to enable the spring body to have the special physical properties of decreasing volume when stretched and first increasing and then decreasing volume when compressed.

[0009] Preferably, the Poisson's ratio v satisfies the following formula:

[0010] Preferably, the value range of the Poisson's ratio v is

[0011] Preferably, the volume ratio λ v Satisfies the following formula: v =λx[1-v0(λx 2 -1)].

[0012] Preferably, the bulk modulus K satisfies the following formula:

[0013] Preferably, the effective stroke

[0014] A compression-expansion-tensile body comprises the above-mentioned spring body metamaterial and an elastic outer garment wrapped around the spring body metamaterial; the compression-expansion-tensile body has the same physical properties as the spring body metamaterial.

[0015] The present application also provides a compression-expansion-shrink body, which is composed of a spring body metamaterial and an elastic outer coat. The compression-expansion-shrink body has the same physical properties as the spring body metamaterial. When the compression-expansion-shrink body is used in the sealing field, it does not need to be installed by external force. When the compression-expansion-shrink body is made into a sealing part, the sealing part can be directly made into a size matching the gap to be sealed, and the sealing part can be placed in the gap to be sealed without applying external force. Usually, when the machine is in a static state, the sealing part is not acted upon by external force, so the sealing effect is achieved and it is not easy to be damaged at the same time, and the durability is stronger. When the machine is in motion, external forces such as mechanical vibration and friction will act on the sealing part, and the sealing part will expand in volume, so that the sealing effect during the mechanical movement is better.

[0016] Preferably, the elastic modulus of the elastic outer garment is smaller than the elastic modulus of the spring body metamaterial.

[0017] Preferably, the compression expansion body is applied in the damping field and the sealing field; the compression expansion body provided in the present application can also be applied in the damping field. Damping can hinder movement. The damping part prepared using the above-mentioned compression expansion body can expand in volume after being subjected to external force. The expanded damping part can enhance the hindering effect on the moving object. Furthermore, the damping part can adjust the resistance size of the hindered movement according to the size of the external force, that is, the damping part can be used as a speed adjustment device.

[0018] Compared with the prior art, this application has the following technical effects:

[0019] (1) The present application provides a spring metamaterial, which has the ability to expand in volume when subjected to force;

[0020] (2) The present application provides a compression-expansion-contraction body, which can be used in the field of sealing and has the characteristics of high durability, simple installation and operation, and good sealing performance when used;

[0021] (3) The compression-expansion-tension-contraction body provided in the present application can also be used in the damping field, and the damping can be adjusted by applying external force to change the volume of the damping. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the spring body metamaterial of the present invention.

[0023] Figure 2 It is a cross-sectional view of the compression-expansion-contraction body of the present invention.

[0024] Figure 3 Schematic diagram of the relationship between the volume ratio and the stretching ratio of the compression-expansion-contraction body of the present invention

[0025] In the figure, elastic outer garment 1 and spring metamaterial 2. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments.

[0027] Example:

[0028] like Figure 1 As shown, a spring metamaterial includes a spring wire spiraled at a spiral angle θ, the initial spiral angle of the spring metamaterial is θ0, the initial Poisson's ratio is v0, the Poisson's ratio v, and the volume ratio is λ v , elastic modulus is E, bulk modulus is K, stretch ratio is λx, diameter of spring wire is d0, pitch of spring wire is t, inner diameter of spring metamaterial is D, effective length is l, inner diameter D satisfies the following formula: The effective length l satisfies the following formula: l = Lsinθ; the inner diameter of the spring after force is D0, the effective length l0, and the stretching ratio of the spring metamaterial before and after force is λ x Satisfies the following formula: Radial deformation ratio λ y Satisfies the following formula: The volume ratio around λ v Satisfies the following formula: Poisson's ratio satisfies the following formula: The Poisson's ratio on engineering materials is the Poisson's ratio under small deformation, that is, the stretching ratio λ x The Poisson's ratio when it is 1 is the initial Poisson's ratio v0 in the initial state of large deformation. The initial Poisson's ratio v0 satisfies the following formula: Where θ0∈(0,π / 2), so v0∈(0,∞), the volume ratio λ v The functional relationship between the stretching ratio λx is as follows: The Poisson's ratio v and the stretch ratio λx have the following functional relationship: It can be seen from the above two formulas that the volume ratio and Poisson's ratio of the spring metamaterial are both nonlinear functions of the stretching ratio and have nothing to do with the stress mode.

[0029] When the spring body is stretched to the elastic limit σ e When , the relationship between the elastic limit and the initial Poisson's ratio can be deduced as follows: From the above formula, it can be known that the ultimate strain corresponding to the elastic limit is determined by the initial Poisson's ratio, and the initial Poisson's ratio of the spring metamaterial can be obtained by testing the elastic limit and elastic modulus.

[0030] The formula for bulk modulus K is: where ε v =λv-1=(1-2v)(λx-1), after derivation, the spring metamaterial satisfies the following formula: It can be seen from the above formula that when the stretching ratio λx of the spring body is 1, the elastic modulus is a constant, the initial Poisson's ratio v0 determines the initial bulk modulus, and the bulk modulus is inversely proportional to the initial Poisson's ratio.

[0031] like Figure 3 As shown, the volume ratio is λ v is 0, the stretch ratio function relationship can be obtained as follows: When the initial Poisson's ratio v0>0.5, then When such a spring-body metamaterial is subjected to stress, its volume decreases when stretched by tension, and its volume first increases and then decreases when compressed.

[0032] Embodiment 2:

[0033] like Figure 2 As shown, a compression-expansion-tension body comprises a spring body metamaterial and an elastic outer garment wrapped around the spring body metamaterial; the spring body metamaterial is stainless steel, the elastic outer garment is a polyurethane casting, the initial spiral angle of the spring body metamaterial is 45°, the elastic modulus E is 2000MPa, the elastic modulus change rate under force is 1%, the elastic modulus of the elastic outer garment is 400MPa, and the effective compression stroke is 0-18.35%.

[0034] Comparative Example 1:

[0035] Compared with Example 2, the initial helix angle of the spring body is 20%, and the other conditions are the same as those of Example 2.

[0036] like Figure 3 As shown, the relationship between the volume ratio and the compression ratio of Example 2 and Comparative Example 1. It can be seen from the figure that the volume ratio of Comparative Example 1 decreases with the increase of the compression ratio, which is the property of conventional elastic material. The initial Poisson's ratio of the material is 0.13, and the bulk elastic modulus is 2721MPa. The volume ratio of Example 2 increases with the increase of the compression ratio, and the properties of unconventional elastic materials appear. Its initial Poisson's ratio is 1, and the bulk elastic modulus is -2000MPa.

[0037] The above description does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A spring metamaterial, characterized in that: The initial helical angle of the spring metamaterial is θ 0 , the initial Poisson's ratio is v 0 , Poisson's ratio v , the volume ratio is λ v , the elastic modulus is E , the bulk modulus is K , the stretching ratio is λx , initial Poisson's ratio v 0 and initial helix angle θ 0 Satisfies the following formula: ; The initial helix angle is When the spring metamaterial is subjected to force, it undergoes a large deformation within the effective travel range. When subjected to tension, the space volume occupied by it decreases. When subjected to pressure, the space volume occupied by it first increases and then decreases. The initial Poisson's ratio v 0 >0.5, elastic modulus E The rate of change is less than 5%; the Poisson's ratio of the spring metamaterial v and volume ratio are nonlinearly related to the stretching ratio.

2. A spring metamaterial as claimed in claim 1, characterized in that: The Poisson's ratio v Satisfies the following formula: 。 3. A spring metamaterial as claimed in claim 2, characterized in that: The Poisson's ratio v The value range is 。 4. The spring metamaterial according to claim 1, characterized in that: The volume ratio λ v Satisfies the following formula: 。 5. The spring metamaterial according to claim 1, characterized in that: The bulk modulus is K Satisfies the following formula: 。 6. The spring metamaterial according to claim 1, characterized in that: The effective stroke .

7. A compression-expansion-contraction body, characterized in that: It comprises the spring body metamaterial according to any one of claims 1 to 6 and an elastic outer garment wrapped around the spring body metamaterial; the compression-expansion-tension body has the same physical properties as the spring body metamaterial.

8. A compression-expansion-contraction body as claimed in claim 7, characterized in that: The elastic modulus of the elastic outer garment is less than the elastic modulus of the spring body metamaterial.

9. The compression-expansion-contraction body according to claim 7, characterized in that: The compression-expansion-tension-contraction body is used in the damping field and the sealing field.

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