A self-locking modular assembled tensile inflation honeycomb protective structure

Abstract

The application discloses a self-locking modular assembly type auxetic honeycomb protective structure, which comprises a plurality of mutually spliced open thin-walled pipes; the open thin-walled pipe is square, comprises two mutually parallel first face plates, an inner plate arranged between the two first face plates and second face plates arranged at both side ends of the first face plates; the inner plate and the second face plate are mutually parallel and are both perpendicular to the first face plate; the second face plates on both sides are symmetrically distributed compared with the inner plate; openings are formed between the two second face plates on the same side of the inner plate. The application provides a self-locking modular assembly type auxetic honeycomb protective structure to solve the problems of high cost, insufficient flexibility in response to demand, large direction dependence and the like of the prior art, realizes good self-locking stability under impact in all directions, and achieves a good balance among manufacturing cost, mechanical property and assembly flexibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of auxetic superstructure honeycomb materials, in particular to a self-locking modular assembled auxetic honeycomb protective structure. BACKGROUND

[0002] Auxetic superstructure materials with negative Poisson's ratio effect, especially metal-based auxetic honeycomb structures with excellent designability and good bearing capacity, are one of the most studied lightweight superstructure materials at present. Negative Poisson's ratio superstructure materials have super-elastic constants and superior performance in shock resistance, noise reduction, blast resistance, fatigue resistance and other series of superior performance, and have broad application prospects in aerospace, automobiles, ships and shock resistance protection and other fields.

[0003] In recent years, traditional integrated auxetic superstructure has inherent defects such as high manufacturing cost and insufficient deployment flexibility, which has been difficult to meet the urgent needs of modern engineering for emergency protection. In view of this challenge, several stacking type modular protective structure design schemes based on self-locking mechanism have been proposed in the prior art. However, the existing self-locking structures generally have the following limitations: (1) the self-locking stability is mostly direction-dependent, and can only maintain self-locking in a specific impact load direction and does not have auxetic effect; (2) in order to realize multi-directional self-locking function, complex configuration design is often used, resulting in rising manufacturing cost and low disassembly efficiency. The above limitations seriously restrict the engineering application of modular protective structure. More importantly, the existing technology still lacks the systematic integration of negative Poisson's ratio and self-locking mechanism, which makes it difficult to fully play the synergistic effect of the two advantages mechanisms. SUMMARY

[0004] The present application provides a self-locking modular assembled auxetic honeycomb protective structure to solve the problems of high cost, insufficient flexible response to demand, and high direction dependence of the auxetic honeycomb protective structure in the prior art, and to achieve the purpose of maintaining good self-locking stability under impact in all directions while achieving a good balance between manufacturing cost, mechanical properties and assembly flexibility.

[0005] The present application is achieved by the following technical solutions:

[0006] A self-locking modular assembled auxetic honeycomb protective structure includes a plurality of mutually spliced open thin-walled tubes; the open thin-walled tube is square-shaped, including two mutually parallel first faceplates, an inner plate arranged between the two first faceplates, and second faceplates arranged at both sides of the end of the first faceplate; the inner plate and the second faceplate are mutually parallel and perpendicular to the first faceplate; the second faceplates on both sides are symmetrically distributed compared to the inner plate; the openings are formed between the two second faceplates on the same side of the inner plate.

[0007] Traditional mechanical metamaterials usually have complex artificial designed cell structures, which are mostly integrated by additive manufacturing technology. Although additive manufacturing technology has made great progress in recent years, the structures of additive manufacturing (especially metal additive manufacturing) contain microcavities and defects, and the strength and reliability are difficult to guarantee. Moreover, the technical maturity of additive manufacturing is still not comparable to traditional manufacturing, and the application range is narrow, the industrial scale is small, and the manufacturing cost is usually much higher than that of traditional manufacturing technology. Therefore, how to manufacture mechanical metamaterials with reliable performance at low cost is still a challenge. In addition, the integrated structure is not flexible enough when responding to demand. Therefore, the development of modularized and separated mechanical metamaterials with cost-effectiveness and deployment flexibility has become an urgent need in the current engineering field. In addition, most of the existing self-locking honeycomb protective structures have serious direction dependence and can only maintain self-locking in a specific impact load direction, and the self-locking stability is low.

[0008] In order to overcome the above problems, the self-locking modularized assembled auxetic honeycomb protective structure is provided, which is composed of a plurality of open thin-walled pipes spliced with each other. The open thin-walled pipe is surrounded by two first panels and four second panels to form a square structure, and an inner plate is arranged at the inner center position, and the opposite ends of the inner plate are connected to the inner walls of the two first panels. Therefore, the open thin-walled pipe in the present application is divided into two parts by the inner plate, and the two parts are symmetrically distributed relative to the inner plate. For the four second panels in an open thin-walled pipe, two are distributed on both sides of the inner plate; for the two second panels located on the same side of the inner plate, there is a gap between them, which constitutes the opening in the present application. Therefore, the opening penetrates the auxetic honeycomb protective structure along the length direction of the second inner plate; the opening is used for inserting a certain second panel on the adjacent open thin-walled pipe, so as to realize the splicing of the open thin-walled pipe.

[0009] In specific use, the present application can be spliced in any side direction of the square structure of the open thin-walled pipe, and the overall size and number can be flexibly adjusted according to the response demand, which has very high use flexibility and can meet the protection needs in different fields such as aerospace, automobile, ship, building, etc. The whole obtained by splicing the special structure of the present application has the characteristics of longitudinal and transverse interlaced buckling, and can realize self-locking in all directions from the outside assembly, so that the structure can also maintain excellent self-locking stability when responding to impact / load in all directions. In addition, the present application can synergistically utilize the superior performance brought by the negative Poisson's ratio effect and the self-locking characteristic, and truly realize the systematic integration of negative Poisson's ratio and self-locking mechanism. In addition, the present application does not need to use additive manufacturing process for production, and the preparation of single open thin-walled pipe can be completed by conventional process, which achieves a good balance between manufacturing cost, self-locking stability, mechanical performance, mechanical performance and assembly flexibility.

[0010] Further, for the two adjacent open thin-walled tubes that are spliced with each other, the inner plates of the two open thin-walled tubes are perpendicular to each other; and two second panels located on the same side of the inner plate of one open thin-walled tube are respectively inserted into two openings of the other open thin-walled tube. The splicing mode provided by the scheme can significantly improve the self-locking stability of the application, and further improve the protection performance of the honeycomb structure.

[0011] Further, the open thin-walled tube satisfies H=L+2t; wherein H is the distance between the thickness centers of the two first panels; L is the distance between the thickness centers of the two second panels located on the two sides of the inner plate; and t is the wall thickness of the open thin-walled tube.

[0012] That is, H can be understood as the distance between the two first panels plus a wall thickness; and L can be understood as the distance between the two second panels on the opposite sides plus a wall thickness. The size limitation of the scheme can ensure that the application has good self-locking effect, and further improve the self-locking stability of the application.

[0013] Further, the open thin-walled tube further satisfies: Wherein h is the distance between the end of the second panel close to the opening and the thickness center of the first panel connected with the second panel. The scheme can further improve the self-locking stability of the application.

[0014] Further, the surface of the open thin-walled tube is provided with a plurality of rows of perforation groups, each row of perforation groups includes a plurality of heart-shaped perforations uniformly distributed along the axial direction; the symmetry axis of the heart-shaped perforation is parallel to the axial direction of the open thin-walled tube, and the directions of the heart-shaped perforations in adjacent two rows of perforation groups are opposite.

[0015] The surface of the open thin-walled tube provided by the scheme includes the surfaces of the first panel, the second panel and the inner plate; a large number of heart-shaped perforations are opened in the above-mentioned area, and the directions of the heart-shaped perforations in adjacent two rows of perforation groups are opposite, so as to ensure that the application has excellent negative Poisson's ratio effect, and improve the impact resistance, explosion resistance, fatigue resistance and other effects of the application. The direction of the heart-shaped perforation can be understood as the direction of the tip of the heart shape.

[0016] Further, the contour of the heart-shaped perforation includes two symmetrically distributed elliptical partial curves, and a circular arc chamfer is arranged at the intersection of the two elliptical partial curves.

[0017] The heart-shaped structure is axisymmetric, and the contour of the heart-shaped perforation in the scheme is an elliptical partial curve on both sides of the symmetry axis. The elliptical partial curve refers to a partial curve segment of an elliptical contour. The elliptical partial curve contains one end point of the elliptical long axis direction. The inventor has verified that this kind of opening mode can significantly improve the negative Poisson's ratio effect of the application, and has excellent plastic energy dissipation effect.

[0018] Further, an auxiliary thin-walled pipe is arranged in the open thin-walled pipe, and an axis of the auxiliary thin-walled pipe is parallel to an axis of the open thin-walled pipe; the auxiliary thin-walled pipe is open at two axial ends.

[0019] After splicing, a square space is formed between the first panel, the second panel and the inner panel in one open thin-walled pipe and the second panel of the other open thin-walled pipe after splicing, and the auxiliary thin-walled pipe is arranged in the square space, so that the protection capability of the structure of the application is significantly improved, and the use stability and safety are further improved.

[0020] Further, the contour of the auxiliary thin-walled pipe is formed by a plurality of sine curves connected in sequence.

[0021] The auxiliary thin-walled pipe in the scheme has a structure similar to a ring, and the surface curve is not a smooth circular arc, but a plurality of sine curves connected in sequence. The auxiliary thin-walled pipe arranged in the application can further improve the protection capability.

[0022] Further, the wall thickness of the auxiliary thin-walled pipe is equal to the wall thickness of the open thin-walled pipe.

[0023] Compared with the prior art, the application has at least the following advantages and beneficial effects:

[0024] 1. The self-locking modular assembly type auxetic honeycomb protection structure can synergistically utilize the superior performance brought by the negative Poisson's ratio effect and the self-locking characteristic, and truly realizes the systematic integration of the negative Poisson's ratio and the self-locking mechanism. The structure has the characteristics of longitudinal and transverse interlaced buckling, and can realize self-locking in all directions from external assembly, so that the structure can maintain excellent self-locking stability when responding to impact / loads in all directions.

[0025] 2. The self-locking modular assembly type auxetic honeycomb protection structure does not need to be produced by using an additive manufacturing process, and the preparation of a single open thin-walled pipe can be completed by a conventional process, so that an excellent balance is achieved between the manufacturing cost, self-locking stability, mechanical performance, mechanical performance and assembly flexibility.

[0026] 3. The self-locking modular assembly type auxetic honeycomb protection structure can be spliced along any side direction of a square structure, the overall size and number can be flexibly adjusted according to the response demand, has extremely high use flexibility, and can meet the protection requirements in different fields such as aerospace, automobile, ship and building.

[0027] 4. The self-locking modular assembly type auxetic honeycomb protection structure ensures excellent negative Poisson's ratio effect through core-type perforation, and improves the impact resistance, blast resistance and fatigue resistance of the application.

[0028] 5. The self-locking modular assembled tensile-inflation honeycomb protective structure has the advantages of significantly enhanced protective capacity, improved stability and safety. BRIEF DESCRIPTION OF DRAWINGS

[0029] The drawings described herein are used to provide further understanding of the embodiments of the present application, form a part of the present application, and do not constitute a limitation of the embodiments of the present application. In the drawings:

[0030] Figure 1 The figure is a structural schematic diagram of the open thin-walled tube in the embodiment of the present application.

[0031] Figure 2 The figure is a front view of the open thin-walled tube in the embodiment of the present application.

[0032] Figure 3 The figure is a splicing schematic diagram of two open thin-walled tubes in the embodiment of the present application.

[0033] Figure 4 The figure is a process schematic diagram of obtaining a heart-shaped perforation in the embodiment of the present application.

[0034] Figure 5 The figure is a structural schematic diagram of the auxiliary thin-walled tube in the embodiment of the present application.

[0035] Figure 6 The figure is a front view of the auxiliary thin-walled tube in the embodiment of the present application.

[0036] Figure 7 The figure is a splicing schematic diagram of four open thin-walled tubes in the embodiment of the present application.

[0037] Figure 8 The figure is a structural schematic diagram of the embodiment of the present application.

[0038] Figure 9 The figure is a process schematic diagram of self-locking performance verification in the embodiment of the present application.

[0039] Figure 10 The figure is a result schematic diagram of self-locking performance verification in the embodiment of the present application.

[0040] Figure 11 The figure is a process schematic diagram of mechanical property test in the embodiment of the present application.

[0041] Figure 12 The figure is a stress-strain curve in the embodiment of the present application.

[0042] Figure 13 The figure is a displacement-energy curve in the embodiment of the present application.

[0043] The marks in the drawings and the corresponding names of parts:

[0044] 1 - first panel, 2 - inner panel, 3 - second panel, 4 - opening, 5 - heart-shaped perforation, 6 - auxiliary thin-walled tube. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments and drawings, and the schematic embodiments of the present application and the description thereof are only used for explaining the present application, and not as a limitation to the present application. In the description of the present application, it should be understood that the orientations or positional relationships indicated by terms such as "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as a limitation to the devices or elements indicated, and therefore cannot be understood as a limitation to the scope of protection of the present application.

[0046] Embodiment 1:

[0047] As shown in Figure 1 With Figure 2 A self-locking modular assembled tensile-honeycomb protective structure is shown, comprising a plurality of mutually spliced open thin-walled tubes; the open thin-walled tube is square, comprising two mutually parallel first panels 1, an inner panel 2 arranged between the two first panels 1, and a second panel 3 arranged at the end of the two first panels 1; the inner panel 2 and the second panel 3 are mutually parallel and perpendicular to the first panel 1; the two second panels 3 on the same side of the inner panel 2 are symmetrically distributed compared to the inner panel 2; the two second panels 3 on the same side of the inner panel 2 form an opening 4.

[0048] The open thin-walled tube satisfies: H = L + 2t; wherein H is the distance between the thickness centers of the two first panels 1; L is the distance between the thickness centers of the two second panels 3 on the two sides of the inner panel 2; and t is the wall thickness of the open thin-walled tube.

[0049] The open thin-walled tube also satisfies: Wherein h is the distance between the end of the second panel 3 close to the opening 4 and the thickness center of the first panel 1 connected to the second panel 3.

[0050] As shown in Figure 3 For two adjacent mutually spliced open thin-walled tubes, the respective inner panels 2 are vertically distributed; and the two second panels 3 on the same side of the inner panel 2 in one open thin-walled tube are respectively inserted into the two openings 4 of the other open thin-walled tube.

[0051] After four open thin-walled tubes are spliced into a square structure, as shown inFigure 7 Continued expansion can result in a structure as shown in Figure 8 .

[0052] The open thin-walled tube in this embodiment can be produced by conventional processes such as hot rolling forming and then laser cutting.

[0053] Embodiment 2

[0054] A self-locking modular assembly type tensile honeycomb protective structure, on the basis of Embodiment 1, a plurality of rows of perforation groups are arranged on the surface of the open thin-walled tube, each row of perforation groups includes a plurality of heart-shaped perforations 5 uniformly distributed along the axial direction; the symmetry axis of the heart-shaped perforation 5 is parallel to the axial direction of the open thin-walled tube, and the orientations of the heart-shaped perforations 5 in adjacent two rows of perforation groups are opposite.

[0055] The profile of the heart-shaped perforation 5 includes two symmetrically distributed elliptical partial curves, and a circular arc chamfer is arranged at the intersection of the two elliptical partial curves. The elliptical partial curve contains one end point of the major axis direction of the ellipse.

[0056] In this embodiment, the heart-shaped perforation 5 is arranged on the surface of the first panel 1, the second panel 3 and the inner panel 2.

[0057] More preferably, as shown in Figure 4 , the heart-shaped perforation 5 is obtained by the following method:

[0058] S1, first draw an ellipse in a two-dimensional coordinate system, so that the major axis of the ellipse is parallel to the X axis and the minor axis of the ellipse is parallel to the Y axis;

[0059] S2, rotate the ellipse by 45° counterclockwise or clockwise around the center, then draw a perpendicular line through the center point, and mirror the perpendicular line to obtain two partially intersecting ellipses; define the intersection region of the two ellipses as the intersection region and the non-intersection region as the independent region;

[0060] S3, keep the intersection region and the two independent regions above or below the center point, and delete the remaining profile lines;

[0061] S4, round processing to obtain the specific profile of the heart-shaped perforation;

[0062] S5, linear array heart-shaped perforation, so that the perforation group is obtained.

[0063] Embodiment 3

[0064] A self-locking modular assembly type tensile honeycomb protective structure, on the basis of Embodiment 1 or 2, as shown in Figures 1 to 8 , further comprising an auxiliary thin-walled tube 6 placed in the open thin-walled tube, the axis of the auxiliary thin-walled tube 6 is parallel to the axis of the open thin-walled tube; the two ends of the auxiliary thin-walled tube 6 are open along the axial direction.

[0065] The auxiliary thin-walled tube 6 is as shown in Figure 5 With Figure 6 The profile is surrounded by several sequentially connected sinusoidal curves.

[0066] In this embodiment, the wall thickness of the auxiliary thin-walled tube 6 is equal to the wall thickness of the open thin-walled tube, and the size satisfies:

[0067] Wherein, P is the wavelength of the sinusoidal curve; A is the amplitude of the sinusoidal curve.

[0068] Example 4:

[0069] This example carries out a comparative test to verify the technical effect of the present application.

[0070] The verification object adopted by the structure of the present application is a tensile expansion honeycomb protective structure as shown in Figure 8 , which is referred to as a verification example; the comparative example is a self-locking protective structure composed of ordinary "I" type structures (this example adopts I-shaped steel) arranged in a longitudinal and transverse staggered manner. The verification example and the comparative example are both provided with the same number and arrangement of auxiliary thin-walled tubes, and the comparative example is not provided with the heart-shaped perforation.

[0071] The size of the open thin-walled tube in the verification example is: L=50mm, H=52mm, T=86mm, t=1mm, h=23.5mm; the size of the heart-shaped perforation is: the corresponding long axis of the ellipse is 10mm, the corresponding short axis of the ellipse is 3mm, the distance between any two adjacent heart-shaped perforations in a group is 1mm, the radius of the rounded portion is 1mm, and the center distance between the two heart-shaped perforations arranged in a staggered manner in the adjacent two groups is 11mm.

[0072] The outer size of the "I" type structure in the comparative example is the same as the size of the open thin-walled tube in the verification example. This example adopts ABAQUS / Explicit to carry out dynamic simulation analysis to verify the self-locking performance of the two structures.

[0073] Self-locking performance verification:

[0074] The way as shown in Figure 9 is adopted, and a small ball is used as the impact object to impact from top to bottom, the initial impact velocity V is 50m / s, and the mass of the small ball is 150kg. The verification result is as shown in Figure 10 . Figure 10 The left graph in is the impact result of the comparative example, and the right graph is the impact result of the verification example.

[0075] Figure 10 FromAs can be seen, the self-locking effect of the protective structure designed in this invention is significantly better than that of the ordinary "I" type structure. The ordinary "I" type structure exhibits obvious splashing phenomenon, which greatly reduces the self-locking and protective performance of the structure.

[0076] It should be noted that no auxiliary thin-walled tube was used in either the verification embodiment or the comparative example during the self-locking performance verification.

[0077] In addition, tests were conducted to verify the mechanical properties of the embodiments:

[0078] In both the verification examples and the comparative examples, the same number and layout of auxiliary thin-walled tubes were provided. The single tube dimensions of the auxiliary thin-walled tubes were: P = 10 mm and A = 1.5 mm.

[0079] Adopting such Figure 11 As shown, a load is applied from top to bottom using a loading plate with an initial impact velocity of 50 m / s and a mass of 150 kg. The stress-strain curve of the protective structure is obtained as follows. Figure 12 As shown, the displacement-energy curve of the protective structure is further obtained based on the force-displacement curve of the loading plate, as shown in the figure. Figure 13 As shown in the displacement-energy curve, the total plastic energy dissipation of the protective structure of this application can reach 104.04 KJ, which is a significant improvement compared with the prior art, proving that this application has excellent protective effect.

[0080] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0081] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Additionally, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

Claims

1. A self-locking modular assembled auxetic cellular protective structure, characterized in that, The open thin-walled tube comprises several mutually spliced open thin-walled tubes; the open thin-walled tube is square-shaped, comprising two mutually parallel first panels (1), an inner panel (2) arranged between the two first panels (1), and second panels (3) arranged at the two side ends of the first panels (1); the inner panel (2) and the second panels (3) are mutually parallel and perpendicular to the first panels (1); the two second panels (3) on the same side of the inner panel (2) are symmetrically distributed compared with the inner panel (2); the two second panels (3) on the same side of the inner panel (2) form an opening (4) between them; For two adjacent mutually spliced open thin-walled tubes, the inner panels (2) of the two open thin-walled tubes are perpendicular to each other; and the two second panels (3) on the same side of the inner panel (2) in one open thin-walled tube are respectively inserted into the two openings (4) of the other open thin-walled tube; The surface of the open thin-walled tube is provided with several rows of perforation groups, each row of perforation groups comprising several heart-shaped perforations (5) uniformly distributed along the axial direction; the symmetry axis of the heart-shaped perforation (5) is parallel to the axial direction of the open thin-walled tube, and the orientations of the heart-shaped perforations (5) in adjacent two rows of perforation groups are opposite.

2. The self-locking modular assembled auxetic cellular protective structure according to claim 1, wherein, The open thin-walled tube satisfies: H = L +2 t ; wherein, H is the distance between the thickness centers of the two first panels (1); L is the distance between the thickness centers of the second panels (3) located on both sides of the inner panel (2); t is the wall thickness of the open thin-walled tube.

3. A self-locking modular assembled auxetic cellular protective structure according to claim 2, characterized in that, The open thin-walled tube also satisfies: ; wherein h is the distance between the end of the second panel (3) near the opening (4) to the center of the thickness of the first panel (1) to which the second panel (3) is connected.

4. The self-locking modular assembled auxetic cellular protective structure according to claim 1, wherein, The contour of the heart-shaped perforation (5) comprises two symmetrically distributed elliptical partial curves, and a circular arc chamfer is arranged at the intersection of the two elliptical partial curves.

5. The self-locking modular assembled auxetic cellular protective structure according to claim 4, wherein, The elliptical partial curve contains one end of the long axis direction of the ellipse.

6. The self-locking modular assembled auxetic cellular protective structure according to claim 1, wherein, An auxiliary thin-walled tube (6) is further arranged in the open thin-walled tube, the axis of the auxiliary thin-walled tube (6) is parallel to the axis of the open thin-walled tube; the two ends of the auxiliary thin-walled tube (6) are open along the axial direction.

7. The self-locking modular assembled auxetic cellular protective structure according to claim 6, wherein, The contour of the auxiliary thin-walled tube (6) is surrounded by several sequentially connected sinusoidal curves.

8. The self-locking modular assembled auxetic cellular protective structure according to claim 6, wherein, The wall thickness of the auxiliary thin-walled tube (6) is equal to the wall thickness of the open thin-walled tube.

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