Metal energy-absorbing thin-walled tube with negative poisson's ratio effect and design method thereof

Abstract

The application provides a metal energy-absorbing thin-walled pipe with a negative Poisson's ratio effect and a design method thereof, comprising a thin-walled pipe body, the thin-walled pipe body is composed of a plurality of unit bodies which are sequentially fixedly connected in a head-to-tail mode from top to bottom, each unit body comprises a pipe and a joint which are fixedly connected, the joint is fixed at the bottom of the pipe, and the wall thickness of the pipe is greater than the wall thickness of the joint. In the technical scheme, the thickness of the metal pipe and the connected joint is inconsistent, the thickness of the metal pipe is greater than the thickness of the connected joint, the metal pipe has better bending strength than a conventional metal pipe with the same thickness when subjected to a bending load, is not prone to deformation and bending when subjected to the same load, and the structure has a negative Poisson's ratio effect when subjected to compression, the metal pipe is shortened in the longitudinal direction and shrinks in the transverse direction when subjected to a compression load, is more prone to densification, and has a better energy-absorbing effect than a conventional metal pipe.

Description

Technical Field

[0001] This invention relates to the field of thin-walled metal energy-absorbing tube technology, and in particular to a thin-walled metal energy-absorbing tube with a negative Poisson's ratio effect and its design method. Background Technology

[0002] Thin-walled metal tubes possess numerous advantages, including simple structure, low manufacturing cost, and minimal axial compression fluctuation, making them suitable as energy-absorbing elements in buffer energy-absorbing devices. Typical energy absorption methods for thin-walled metal tubes include three main types: first, energy absorption through tearing deformation of the tube wall; second, energy absorption through plastic deformation caused by axial crushing; and third, energy absorption through tube expansion. Among these, tearing energy absorption is difficult to control and has a high load value; compared to the other two types of energy absorbers, expanded tubes are heavier when absorbing the same amount of energy, making installation and use less convenient; axial crushing energy absorption produces the largest deformation, resulting in stable buckling during compression, thus absorbing more energy in a controllable manner.

[0003] The greater the energy absorbed by a buffer energy absorber, the higher its energy absorption efficiency, the more stable its buffering force, and the smaller its initial peak load, the greater its protective effect. Energy absorption characteristics are an important research direction in the field of protection. How to dissipate impact energy and reduce impact load by means of destruction, plastic deformation, etc., and make the impact process more stable has become a benchmark for evaluating whether the impact resistance performance of energy-absorbing structures is good.

[0004] To achieve good impact resistance, the placement of energy-absorbing elements is a primary solution. Negative Poisson's ratio metamaterials are renowned not only for their unique mechanical properties but also for their excellent energy absorption. Therefore, it is essential to design thin-walled metal tubes with negative Poisson's ratio effects that possess greater bending strength and can absorb energy through axial crushing. Summary of the Invention

[0005] The purpose of this invention is to provide a metal energy-absorbing thin-walled tube with a negative Poisson's ratio effect and its design method. The metal thin-walled tube is made into a specific shape to have a negative Poisson's ratio effect. It can achieve the negative Poisson's ratio effect while deforming, and will have better energy absorption effect and better specific energy absorption compared with traditional metal thin-walled tubes.

[0006] According to one objective of the present invention, the present invention provides a metal energy-absorbing thin-walled tube with a negative Poisson's ratio effect, comprising a thin-walled tube body, the thin-walled tube body being composed of a plurality of unit bodies fixedly connected end to end from top to bottom, each unit body comprising a tube and a section fixedly connected, the section being fixed to the bottom of the tube, and the wall thickness of the tube being greater than the wall thickness of the section.

[0007] Furthermore, the thin-walled tube body is a curved surface rotational structure formed by a curve around a central axis.

[0008] Furthermore, each of the said unit bodies has the same height.

[0009] Furthermore, the tube and the section are integrally formed.

[0010] Furthermore, the thin-walled tube body has an axisymmetric structure about its central axis.

[0011] Furthermore, the tube and the section are made of metal.

[0012] Furthermore, the thin-walled tube body is formed by seven unit bodies arranged and connected in an array in the vertical direction.

[0013] Furthermore, the upper and lower end faces of the thin-walled tube body have the same diameter.

[0014] According to another objective of the present invention, the present invention provides a design method for the above-mentioned metal energy-absorbing thin-walled tube with negative Poisson's ratio effect, comprising the following steps:

[0015] S1, determine the distance L between the upper and lower end faces of the thin-walled tube body, and take the y-axis as the central axis of the thin-walled tube body;

[0016] S2, take the top reference plane as reference plane one that coincides with the top end plane, and draw a circle with radius r1 centered on the central axis in reference plane one; take a plane parallel to reference plane one at a distance L / 2 from reference plane one in the negative y-axis direction as reference plane two, and draw a circle with radius r2 centered on the central axis in reference plane two, where r2 < r1; select a plane parallel to reference plane two at a distance L / 2 from reference plane two in the negative y-axis direction as reference plane three, and sketch a circle with radius r1 on reference plane three;

[0017] S3, the curve of the side surface of the thin-walled tube body is drawn by three-point arc. The first point is the rightmost endpoint of the circle in reference surface one, the second point is the rightmost endpoint of the circle in reference surface two, and the third point is the rightmost endpoint of the circle in reference surface three. Connect the three points in the three reference surfaces with a curve using the three-point arc command, and then rotate the curve around the y-axis to form the corresponding surface.

[0018] S4. After creating the surface, use the Trim Surface command to trim the created surface revolution body into multiple element bodies. The multiple element bodies have the same height. After trimming into multiple element bodies, trim the element bodies into two parts: tube and section.

[0019] S5. After creating and trimming the surface, thicken the corresponding surface accordingly. The thickness of the pipe is greater than the thickness of the section. The modeling is now complete.

[0020] Furthermore, in S4, the number of units cut out is 7.

[0021] The technical solution of this invention has a metal tube and a connecting section with different thicknesses. The thickness of the metal tube is greater than that of the connecting section. This results in better bending strength compared to traditional metal tubes of the same thickness when subjected to bending loads. It is less prone to deformation and bending under the same load. Moreover, this structure has a negative Poisson's ratio effect when compressed. Under compressive loads, the metal tube shortens longitudinally and contracts laterally, making it easier to achieve densification. This results in better energy absorption compared to ordinary metal tubes. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0024] Figure 2 This is a front view of an embodiment of the present invention;

[0025] Figure 3 This is a top view of an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the structure of a unit body according to an embodiment of the present invention;

[0027] Figure 5 This is a top view of the unit body in an embodiment of the present invention;

[0028] Figure 6 This is a front view of the unit body in an embodiment of the present invention;

[0029] Figure 7 This is an uncut view of the curved surface of the thin-walled tube body according to an embodiment of the present invention.

[0030] In the diagram: 1. Thin-walled tube body; 2. Unit body; 3. Tube; 4. Section. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] Example 1

[0035] like Figures 1-7 As shown,

[0036] A thin-walled metal energy-absorbing tube with a negative Poisson's ratio effect includes a thin-walled tube body 1, which is composed of multiple unit bodies 2 fixedly connected end-to-end from top to bottom. The outer contour of the thin-walled tube body composed of multiple unit bodies 2 is a curved rotational structure. Each unit body 2 has the same height, and each unit body 2 includes a tube 3 and a section 4 fixedly connected to each other. The section 4 is fixed to the bottom of the tube 3, and the tube 3 and the section 4 at the bottom of the tube 3 are integrally formed structures, and the wall thickness of the tube 3 is greater than the wall thickness of the section 4.

[0037] In this embodiment, the thin-walled tube body 1 has an axisymmetric structure about the central axis. In this embodiment, the metal energy-absorbing thin-walled tube is formed by seven unit bodies 2 arranged and connected in a vertical array. Each unit body consists of a corresponding tube 3 and a section 4 located at the bottom of the tube 3. The thickness of the tube 3 and the connected section 4 are different. The thickness of the tube is a, and the thickness of the connected section 4 is b. The thickness a of the tube 3 is greater than the thickness b of the section 4.

[0038] The design method of the metal energy-absorbing thin-walled tube with negative Poisson's ratio effect in this embodiment is as follows:

[0039] In this embodiment, the distance between the upper and lower end faces of the thin-walled tube body 1 is L. The upper and lower end faces are composed of curved surfaces formed by rotating a curve around a central axis. The upper end face that coincides with the upper reference plane is designated as reference plane one. A circle with radius r1 is drawn on reference plane one. A plane parallel to reference plane one is selected at a distance L / 2 from reference plane one in the negative y-axis direction as reference plane two. A circle with radius r2 (r2 < r1) is drawn on reference plane two. A plane parallel to reference plane two is selected at a distance L / 2 from reference plane two in the negative y-axis direction as reference plane three, i.e., the lower end face. The sketch on reference plane three is a circle with radius r1.

[0040] The curved surface of the side of the thin-walled tube body 1 is drawn using a three-point arc. The first point is the rightmost endpoint of the circle in the upper end face sketch, with a radius of r1. The second point is the rightmost endpoint of the circle in reference surface two, with a radius of r2. The third point is the rightmost endpoint of the circle in reference surface three. After determining the three points for drawing the arc, the three points are connected by a curve using the three-point arc command. Then, the curve is rotated around the y-axis to form the corresponding curved surface.

[0041] After creating the surface, the surface revolution body is trimmed into n unit bodies with the same height using the trim surface command. After trimming into n unit bodies, the unit bodies are trimmed into two parts: tube and section. After the surface is created and trimmed, the corresponding surface is thickened with the corresponding thickness. The thickness of the tube is a, and the thickness of the section is b (a>b). In this way, the modeling of a metal energy-absorbing thin-walled tube with negative Poisson's ratio effect based on the king palm tree and its design method are completed.

[0042] The structure of this invention is based on the structure of a large palm tree. The thickness of the metal tube and the connecting joints are not the same. The thickness 'a' of the metal tube is greater than the thickness 'b' of the connecting joint. This allows it to have better bending strength than traditional metal tubes of the same thickness when subjected to bending loads. It is not easy to deform and bend under the same load. Moreover, this structure has a negative Poisson's ratio effect when compressed. When subjected to compressive loads, the metal tube shortens longitudinally and contracts laterally. It is also easier to achieve densification. Compared with ordinary metal tubes, it has a better energy absorption effect.

[0043] This invention provides a metal energy-absorbing tube based on the giant palm tree, exhibiting a negative Poisson's ratio effect and good toughness. By designing the tube and sections with different thicknesses, this structure has better bending strength than traditional metal tubes, and its deformation under bending loads is relatively smaller compared to ordinary metal tubes.

[0044] The structural boundary of this invention is a curved surface formed by rotating a curve, which can undergo torsion under compressive loads, absorbing more energy through torsion compared to other metal tubes. This device easily enters a densification stage under large loads; under compressive loads, the overall structure shrinks, and the density decreases accordingly, entering the densification stage. The structural strength and stiffness also increase accordingly. This device exhibits a good negative Poisson's ratio effect when deformed under compressive loads.

[0045] This invention uses metal thin-walled tubes and connecting joints with varying thicknesses to improve their toughness and increase their bending strength. Furthermore, this invention shapes the metal thin-walled tubes to exhibit a negative Poisson's ratio effect, achieving this effect during deformation. Compared to traditional metal thin-walled tubes, this results in better energy absorption and higher specific energy absorption.

[0046] This invention can improve specific energy absorption, and has a better energy absorption effect compared with traditional metal tubes. The introduced curved design torsional boundary can absorb more energy through torsion when subjected to load impact, and can cope with deformation under large impact, thus ensuring people's safety.

[0047] This invention exhibits a negative Poisson's ratio effect upon impact, causing the component to become denser and thus providing better rigidity compared to traditional metal tubes, thereby better resisting deformation. Furthermore, the metal tubes of this invention have varying thicknesses, making them less prone to bending under lateral loads and exhibiting superior bending strength.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thin-walled metal energy-absorbing tube with a negative Poisson's ratio effect, characterized in that, The device includes a thin-walled tube body, which is composed of multiple unit bodies that are fixedly connected end to end from top to bottom. Each unit body includes a tube and a section that are fixedly connected. The section is fixed to the bottom of the tube, and the wall thickness of the tube is greater than the wall thickness of the section. The thin-walled tube body is a curved surface rotational structure formed by a curve around a central axis. Each unit body has the same height. The tube and the section are integrally formed. The design method for the metal energy-absorbing thin-walled tube with negative Poisson's ratio effect includes the following steps: S1, determine the distance L between the upper and lower end faces of the thin-walled tube body, and take the y-axis as the central axis of the thin-walled tube body; S2, take the top reference plane as reference plane one that coincides with the top end plane, and draw a circle with radius r1 centered on the central axis in reference plane one; take a plane parallel to reference plane one at a distance L / 2 from reference plane one in the negative y-axis direction as reference plane two, and draw a circle with radius r2 centered on the central axis in reference plane two, where r2 < r1; select a plane parallel to reference plane two at a distance L / 2 from reference plane two in the negative y-axis direction as reference plane three, and sketch a circle with radius r1 on reference plane three; S3, the curve of the side surface of the thin-walled tube body is drawn by three-point arc. The first point is the rightmost endpoint of the circle in reference surface one, the second point is the rightmost endpoint of the circle in reference surface two, and the third point is the rightmost endpoint of the circle in reference surface three. Connect the three points in the three reference surfaces with a curve using the three-point arc command, and then rotate the curve around the y-axis to form the corresponding surface. S4. After creating the surface, use the Trim Surface command to trim the created surface revolution body into multiple element bodies. The multiple element bodies have the same height. After trimming into multiple element bodies, trim the element bodies into two parts: tube and section. S5. After creating and trimming the surface, thicken the corresponding surface accordingly. The thickness of the pipe is greater than the thickness of the section. The modeling is now complete.

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