Negative Poisson's ratio bionic sealing element of bamboo fungus-like structure

Abstract

The invention discloses a negative Poisson's ratio bionic sealing element of a bamboo fungus-like structure, and belongs to the technical field of sealing structures, the whole sealing element is of a tubular structure and comprises a base body and a negative Poisson's ratio reinforcing structure embedded in the base body, the negative Poisson's ratio reinforcing structure is located in the whole tubular sealing element, and the negative Poisson's ratio reinforcing structure is embedded in the base body. According to the negative Poisson's ratio reinforcing structure, through the unique bionic structural design, the sealing piece shows the negative Poisson's ratio effect and shows the mechanical characteristic that the rigidity is gradually increased under the action of a pressure head, structural gaps can be effectively filled, and the sealing performance of the sealing piece is improved. Local rigidity of a contact area is increased, contact stress is improved, and therefore sealing performance is improved. In addition, when the sealing piece is subjected to the action of internal inflation air pressure, the negative Poisson's ratio structure can generate radial expansion, the fitting degree and contact pressure of the sealing face are further improved, and the overall sealing effect is enhanced.

Description

Technical Field

[0001] The present invention relates to the field of sealing structure technology, and specifically to a bionic sealing structure design with negative Poisson's ratio mechanical properties, which can be applied to aerospace, energy, nuclear industry and other fields, and helps to improve the sealing performance and service life of equipment in complex environmental conditions such as structural compression, internal and external pressure difference, vibration, etc. Background Art

[0002] With the development of industrial technology, various harsh and complex environmental conditions have put forward higher requirements on the performance of seals. In the fields of aerospace, petrochemical, energy, nuclear industry, etc., equipment often operates under complex environmental conditions such as structural compression, internal and external pressure difference, vibration, etc., and seals need to maintain a stable sealing effect for a long time. Especially in aviation structures with internal and external pressure difference and mechanical systems with high-frequency vibration, the sealing performance and service life of seals directly affect the safety and economy of equipment.

[0003] Currently, traditional seals are mostly made of polymers such as rubber. These materials have good elastic sealing properties and can produce large recoverable deformations under structural compression to fill structural gaps and achieve sealing effects. However, existing seals often face problems such as unstable sealing effects, difficult to adjust resilience, significant loss of stiffness, and insufficient vibration resistance under complex environmental conditions such as structural compression, internal and external pressure differences, and vibration. The risk of sealing failure increases, affecting the normal operation of the equipment and even posing safety hazards.

[0004] Negative Poisson's ratio structural materials have become a potential solution to this problem due to their superior mechanical properties. Unlike traditional materials, negative Poisson's ratio materials will shrink laterally under uniaxial pressure and expand laterally under uniaxial tension. This structure has significant advantages in terms of anti-sag performance, shear bearing capacity, fracture resistance and energy absorption, making it more resistant to deformation in a dynamic environment and able to extend the service life of seals under service conditions. Therefore, applying negative Poisson's ratio structures to the design of seals can effectively improve the durability and sealing reliability of seals and meet the strict requirements under service conditions. Summary of the invention

[0005] The present invention provides a negative Poisson's ratio bionic seal with a bamboo fungus-like structure, which is mainly used to solve the problems of unstable sealing effect, difficult to adjust resilience, easy loss of rigidity, insufficient anti-vibration ability, etc. of existing seals under complex environments such as structural compression, internal and external pressure difference, and vibration. Through the unique bionic structure design, the seal exhibits a negative Poisson's ratio effect, and exhibits a mechanical property of gradually increasing rigidity under the action of the pressure head, which can effectively fill the structural gap, increase the local rigidity of the contact area, and increase the contact stress, thereby improving the sealing performance. In addition, when the seal is subjected to the internal inflation pressure, the negative Poisson's ratio structure can produce radial expansion, further improving the fit and contact pressure of the sealing surface, and enhancing the overall sealing effect.

[0006] To achieve the above object, a technical solution adopted by the present invention is:

[0007] A negative Poisson's ratio bionic seal with a bamboo fungus-like structure, the seal is a tubular structure as a whole, including a matrix and a negative Poisson's ratio reinforcement structure embedded in the matrix, and the negative Poisson's ratio reinforcement structure is located inside the entire tubular seal. This design enables the seal to exhibit a negative Poisson's ratio effect under the action of external force and air pressure, so as to achieve a more excellent sealing performance.

[0008] In the above technical solution, the cross-sectional geometric shape of the tubular structure includes O-shape, Ω-shape, mouth-shape, heart-shape and other geometric configurations.

[0009] In the above technical solution, the matrix material includes polymer materials with excellent mechanical properties, high temperature resistance, chemical corrosion resistance and good processability, such as epoxy resin, rubber, polyurethane, polytetrafluoroethylene, polyphenylene sulfide, polyetheretherketone, phenolic resin, etc. The selection of the matrix material is usually determined by factors such as the physical properties, chemical stability, temperature resistance, wear resistance, etc. required by the seal.

[0010] In the above technical solution, the negative Poisson's ratio reinforced structural material includes aramid, silicon carbide, nickel-based alloy, etc., which are used to improve the mechanical strength, temperature resistance, chemical corrosion resistance and other properties of the structure.

[0011] In the above technical solution, the negative Poisson's ratio reinforcement structure is bent into a specific shape when used in combination and embedded in the interior of the rubber matrix. Preferably, the negative Poisson's ratio reinforcement structure is curled into a closed tubular structure with the same shape as the matrix.

[0012] In the above technical solution, Poisson's ratio is the transverse deformation coefficient, which characterizes the transverse deformation characteristics of the material in the direction perpendicular to the force. Poisson's ratio is defined as the transverse strain of the material in the direction of elastic loading ( ) and longitudinal strain ( ) is a negative number, that is Traditional materials typically exhibit a positive Poisson's ratio, meaning they shrink laterally when stretched, while negative Poisson's ratio structures have the opposite effect, expanding laterally when stretched and shrinking laterally when compressed.

[0013] In the above technical solution, the negative Poisson's ratio reinforcement structure is a bamboo fungus-like bionic structure design, and the periodic micro-units of the structure are composed of hexagons. The periodic hexagonal micro-units refer to the smallest units that can reflect the geometric characteristics of the structure, including an upper side, a lower side and four side sides. The upper side and the lower side are arranged in parallel, and the four side sides are divided into a first group and a second group, each group includes two side sides, and the two groups of side sides are mirror-imaged, wherein the two end points of the first group of side sides are connected to the two end points of the upper side and are inclined inward at a certain angle. The other two endpoints of the first set of sides are connected to the two endpoints of the second set of sides; the two endpoints of the second set of sides are connected to the two endpoints of the bottom side, and are inclined inward at an angle of , the other two endpoints of the second set of sides are connected to the two endpoints of the first set of sides, where the lengths of the top and bottom sides are , the length of the side is , the width of the top, bottom and four sides is , the thickness of the negative Poisson's ratio reinforcement structure is When the structure is stretched, the concave angles open up and the sides rotate, causing the overall structure to expand laterally, thus achieving a negative Poisson's ratio effect.

[0014] In the above technical solution, the Poisson's ratio and elastic modulus of the negative Poisson's ratio reinforcement structure along the loading direction are as shown in the following formula:

[0015] ,

[0016] ,

[0017] in, It is the elastic modulus of the material constituting the cellular units. By adjusting the geometric dimensions of the micro-geometric units of the bamboo fungus-like structure, the size of the negative Poisson's ratio effect of the structure can be changed. It can be optimized by adjusting the structural geometric parameters to adapt to different sealing areas and different service conditions.

[0018] In the above technical solution, the feedback force exerted on the pressure head by the tubular seal is expressed as follows:

[0019] ,

[0020] in, is the feedback force exerted on the pressure head by the tubular seal. is the length of the tubular seal, is the shape factor, which is related to the geometric configuration of the seal. is the elastic modulus of the structure, is the maximum inner diameter of the seal before deformation, is the maximum inner diameter of the seal after expansion due to the negative Poisson’s ratio effect, is the distance the pressure head presses down, The internal and external pressures to which the seal is subjected.

[0021] The contact stress is expressed as follows:

[0022] ,

[0023] in, is the feedback force exerted on the pressure head by the tubular seal. is the contact area between the pressure head and the sealing surface. The contact stress is positively correlated with the sealing performance. The greater the contact stress, the better the sealing performance of the seal.

[0024] When the tubular seal is inflated, the inside of the seal expands due to the air pressure, and the negative Poisson's ratio structure stretches under the action of the air pressure. Due to the negative Poisson's ratio effect, the diameter of the seal tube becomes thicker. The contact surface between the seal and the structure can be increased, and pressure is applied to the contact surface, so that the contact area has a greater contact stress, thereby improving the sealing performance of the structure. When the pressure head and the contact surface of the seal are squeezed and compressed, the negative Poisson's ratio effect causes the remaining material of the seal to retract to the pressure zone, and the pressure zone locally exhibits an effect of enhanced rigidity, which can effectively improve the anti-sag performance of the structure and further increase the contact stress of the local contact area. Therefore, the negative Poisson's ratio bionic seal of the bamboo fungus-like structure designed by the present invention can enhance the sealing performance of the structure.

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The present invention uses an innovative bionic structural design to make the seal exhibit a negative Poisson's ratio effect, showing a mechanical characteristic of gradually increasing stiffness, which can better fill the structural gaps and significantly improve the sealing performance of the seal. This design can increase the local stiffness of the contact area and increase the contact stress, thereby enhancing the seal's ability to resist deformation under high vibration and internal and external pressure difference environments, ensuring that the seal still has an excellent sealing effect under different stress states and dynamic conditions.

[0027] (2) The present invention embeds a negative Poisson's ratio structure inside the seal. When subjected to internal air pressure, the structure stretches and expands, causing the seal to become thicker, thereby increasing the contact area between the seal and the pressure head, improving the fit and contact pressure of the sealing surface, and enhancing the overall sealing effect.

[0028] (3) The seal of the present invention has adjustable resilience performance through the optimization design of geometric parameters. The requirements of different sealing areas under various pressure, temperature or strain environments can be met by adjusting the geometric deformation response of the seal, thereby improving the adaptability of the system and the reliability of the seal, so that it has excellent sealing performance in various service conditions.

[0029] (4) The negative Poisson's ratio structure of the present invention has advantages over traditional sealing materials in terms of resistance to indentation, shear bearing capacity, fracture resistance and energy absorption. Under uniaxial tension, the lateral dimension of the negative Poisson's ratio material increases, so that the seal provides higher resistance to deformation under dynamic conditions. Its superior fracture resistance and energy absorption characteristics can extend the service life of the seal under service conditions and improve the reliability and durability of the seal under high pressure and vibration service conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the overall cross-section and tubular shape of the sealing structure in an embodiment of the present invention.

[0031] Figure 2 Schematic diagram of the plan view of the negative Poisson's ratio reinforcement structure of the bamboo fungus-like structure in an embodiment of the present invention.

[0032] Figure 3 Schematic diagram of structural parameters in an embodiment of the present invention.

[0033] Figure 4 Schematic diagram of force-displacement curve of negative Poisson's ratio structure in an embodiment of the present invention.

[0034] Figure 5 Schematic diagram of the anti-sag performance of negative Poisson's ratio effect in an embodiment of the present invention.

[0035] Figure 6 It is a schematic diagram of the compression of the sealing member and the feedback force exerted on the pressure head by the tubular sealing member in an embodiment of the present invention.

[0036] Among them, 1-1 is the matrix, and 1-2 is the negative Poisson's ratio reinforcement structure. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical methods in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work results are within the scope of protection of the present invention.

[0038] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0039] Example

[0040] The present invention provides a negative Poisson's ratio bionic seal of a bamboo fungus-like structure, which is a circular tube structure as a whole and has an O-shaped cross section. Figure 1 As shown. The seal consists of two major components: silicone rubber as the base 1-1, which has excellent high temperature resistance and anti-aging performance; aramid fabric as the negative Poisson's ratio reinforcement structure 1-2, designed as a negative Poisson's ratio structure to improve sealing performance. The structure has a negative Poisson's ratio property and generates significant resilience through deformation, meeting the sealing requirements of the seal under complex service conditions such as structural compression, internal and external pressure difference and vibration.

[0041] Figure 2 The negative Poisson's ratio reinforcement structure of the bamboo fungus is a schematic diagram. The negative Poisson's ratio reinforcement structure adopts a bamboo fungus-like micro-geometric design. The periodic micro-unit of the structure is composed of a hexagon, including an upper side, a lower side and four side sides. The upper side and the lower side are arranged in parallel. The four side sides are divided into a first group and a second group. Each group includes two side sides. The two groups of side sides are mirrored. The two end points of the first group of side sides are connected to the two end points of the upper side and tilted inward at a certain angle ( ), the other two endpoints of the first set of sides are connected to the two endpoints of the second set of sides; the two endpoints of the second set of sides are connected to the two endpoints of the bottom side, tilted inward at a certain angle ( ), the other two endpoints of the second set of sides are connected to the two endpoints of the first set of sides, where the lengths of the top and bottom sides are , the length of the side is , the width of the top, bottom and four sides is , the thickness of the negative Poisson's ratio reinforcement structure is , when used in conjunction, it is bent into a specific shape and embedded in the rubber matrix. For example, the negative Poisson's ratio reinforcement structure is curled into a closed tubular structure with the same shape as the matrix. The negative Poisson's ratio reinforcement structure design provides additional structural rigidity and sealing performance.

[0042] Figure 3 The bamboo fungus-like negative Poisson's ratio reinforcement structure has a periodic micro-unit, which is composed of hexagons. The periodic micro-unit refers to the smallest unit that can reflect the geometric characteristics of the structure.

[0043] Its geometric parameters include the length of the upper and lower sides , side length and the angle between the side and the bottom , and the width and thickness Under the action of force, the geometric unit expands laterally due to the expansion of the concave angle and the lateral rotation, showing a significant negative Poisson's ratio effect. Its geometric dimensions are as follows: the length of the upper and lower sides , side length , the angle between the side and the bottom ,width and thickness , the elastic modulus is With the cooperation of the above parameters, the negative Poisson's ratio structure can produce radial expansion under unidirectional tension, thereby showing a negative Poisson's ratio effect. By adjusting the geometric dimensions of the concave hexagonal microstructure, the performance of the seal can be flexibly adjusted to meet the needs of different working conditions.

[0044] Poisson's ratio of the structure along the loading direction , elastic modulus .

[0045] Figure 4 It is a schematic diagram of the force-displacement curve of the negative Poisson's ratio structure. Figure 5 Schematic diagram of the anti-sag performance of negative Poisson’s ratio effect. Figure 4 The horizontal axis coordinate X is displacement, and the vertical axis coordinate Y is force. When external pressure acts, the negative Poisson's ratio structure shows a mechanical characteristic of gradually increasing stiffness, that is, it has good flexibility in the initial compression stage to adapt to deformation and fill structural gaps. Figure 5 As shown in Figure 2, when the pressure increases further, the structure shrinks laterally due to the negative Poisson's ratio effect, causing the material to be concentrated in the contact area, which enhances the local stiffness of the contact area and further increases the contact stress.

[0046] Figure 6 The diagram shows the compression of the seal and the feedback force exerted on the pressure head by the tubular seal. When the tubular seal is inflated, the air pressure stretches and expands the negative Poisson's ratio reinforcement structure. Due to the negative Poisson's ratio effect, the lateral dimension of the structure increases, resulting in a thicker tube diameter of the seal and a significantly increased contact area. The thickening of the tube diameter not only increases the contact area between the seal and the sealed surface, but also applies greater pressure to the contact surface, thereby significantly increasing the contact stress in the contact area. The larger contact stress and enhanced feedback force enable the seal to provide excellent sealing performance under high pressure and vibration environments.

[0047] When the internal and external pressure difference , seal length , head compression , pipe diameter expansion increment , contact width after compression , contact area , shape coefficient according to design experience value , the feedback force on the pressure head from the tubular seal is , contact stress .

[0048] When the contact stress reaches 10.92MPa, it can ensure effective compression between the sealing surfaces, thereby significantly reducing leakage. The larger feedback force of 10992N not only improves the sealing reliability, but also strengthens the structure's ability to adapt to vibration and pressure difference changes, ensuring sealing stability in complex service environments.

[0049] The specific implementation methods of the invention are described in detail above, but as examples, the present invention is not limited to the specific implementation methods described above. For those skilled in the art, any equivalent modification or substitution of the invention is also within the scope of the present invention. Therefore, the equivalent transformation, modification, improvement, etc. made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A negative Poisson's ratio bionic seal with a bamboo fungus-like structure, characterized in that: The seal is a tubular structure as a whole, comprising a matrix and a negative Poisson's ratio reinforcement structure embedded in the matrix, and the negative Poisson's ratio reinforcement structure is located inside the entire tubular seal.

2. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 1, characterized in that: The negative Poisson's ratio enhances the transverse strain of the material in the elastic loading direction of the structure With longitudinal strain The ratio is negative, that is .

3. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 1, characterized in that: The negative Poisson's ratio reinforcement structure is rolled into a closed tubular structure having the same shape as the base.

4. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 1, characterized in that: The cross-sectional geometric shapes of the tubular structure include O-shape, Ω-shape, mouth-shape or heart-shape.

5. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 1, characterized in that: The matrix material includes epoxy resin, rubber, polyurethane, polytetrafluoroethylene, polyphenylene sulfide, polyetheretherketone or phenolic resin.

6. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 1, characterized in that: The negative Poisson's ratio reinforcement structural material includes aramid, silicon carbide or nickel-based alloy.

7. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 1, characterized in that: The negative Poisson's ratio reinforcement structure is a bamboo fungus-like bionic structure design. The periodic micro-unit of the structure is composed of a hexagon, including an upper side, a lower side and four side sides. The upper side and the lower side are arranged in parallel. The four side sides are divided into a first group and a second group. Each group includes two side sides. The two groups of side sides are arranged in a mirror image. The two end points of the first group of side sides are connected to the two end points of the upper side and are inclined inward at a certain angle. , the other two endpoints of the first set of sides are connected to the two endpoints of the second set of sides; The two endpoints of the second set of sides are connected to the two endpoints of the bottom side, tilted inwards , the other two endpoints of the second set of sides are connected to the two endpoints of the first set of sides, where the lengths of the top and bottom sides are , the length of the side is , the width of the top, bottom and four sides is , the thickness of the negative Poisson's ratio reinforcement structure is .

8. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 7, characterized in that: The Poisson's ratio and elastic modulus of the negative Poisson's ratio reinforcement structure along the loading direction are shown in the following formula: ， ， in, is the elastic modulus of the material constituting the cellular unit.

9. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 7, characterized in that: The feedback force on the pressure head from the tubular seal is given by the following formula: ， in, is the feedback force exerted on the pressure head by the tubular seal. is the length of the tubular seal, is the shape factor, is the elastic modulus of the structure, is the maximum inner diameter of the seal before deformation, is the maximum inner diameter of the seal after expansion due to the negative Poisson’s ratio effect, is the distance the pressure head presses down, The internal and external pressures to which the seal is subjected.

10. The negative Poisson's ratio bionic seal of a bamboo fungus-like structure according to claim 7, characterized in that: The contact stress is given by the following formula: ， in, is the feedback force exerted on the pressure head by the tubular seal. It is the contact area between the pressure head and the sealing surface.

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