CN111139936B - High-symmetry negative Poisson ratio structural unit based on folding rod shear type unit and inhaul cable - Google Patents
High-symmetry negative Poisson ratio structural unit based on folding rod shear type unit and inhaul cable Download PDFInfo
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- CN111139936B CN111139936B CN202010073081.3A CN202010073081A CN111139936B CN 111139936 B CN111139936 B CN 111139936B CN 202010073081 A CN202010073081 A CN 202010073081A CN 111139936 B CN111139936 B CN 111139936B
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/34—Extraordinary structures, e.g. with suspended or cantilever parts supported by masts or tower-like structures enclosing elevators or stairs; Features relating to the elastic stability
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/38—Connections for building structures in general
- E04B1/58—Connections for building structures in general of bar-shaped building elements
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/14—Conveying or assembling building elements
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/38—Connections for building structures in general
- E04B1/58—Connections for building structures in general of bar-shaped building elements
- E04B2001/5868—Hinged connections
Abstract
The invention discloses a high-symmetry negative Poisson ratio structural unit based on a folding rod shear type unit and a inhaul cable, which is characterized by comprising the following components: the annular shear type structural unit is formed by connecting shear type hinge units end to end; the scissor-type hinge unit is formed by hinging two folding rods in the middle of the folding rods; the annular shear type structure unit comprises an outer node, an inner node and a pivot node which are positioned at the end part of the shear type hinge unit; the pull cables are connected among all internal nodes which are symmetrical by taking the center in the annular scissor-type structure unit as a center; and the second-class guy cables are connected between the internal nodes and the external nodes of every two adjacent scissor hinge units in the annular scissor structure unit. When the second type guy cable is shortened, the structural unit is expanded, and when the first type guy cable is shortened, the structural unit is contracted. The basic units are periodically arranged on a two-dimensional plane, a large-scale negative poisson ratio structure with periodic symmetry can be formed, and the method has a good application prospect in a negative poisson ratio cable-rod structure system.
Description
Technical Field
The invention relates to a method applied to building structure design and modern space structure design, in particular to an expandable high-symmetry negative poisson ratio cable-rod structure unit.
Background
The negative poisson's ratio structure is also called auxetic structure, and is expressed in uniaxial tension (or compression). The expansion (or contraction) can occur in the direction perpendicular to the loading direction, so that the negative Poisson ratio structure has unique properties different from the common structure, and has higher compression resistance, shearing resistance and energy absorption and dissipation capacity. In recent years, the negative poisson ratio structure gradually becomes a hot point of research in various fields due to the excellent performance of the negative poisson ratio structure, has wide application in the aerospace field and the medical field, and has wide application prospect in engineering.
Disclosure of Invention
The technical problem is as follows: the invention provides a high-symmetry negative Poisson ratio structural unit based on a folding rod shear type unit and a inhaul cable, which can be expanded and derived and can be efficiently applied to a negative Poisson ratio structural system.
The technical scheme is as follows:
the utility model provides a high symmetry negative poisson ratio constitutional unit based on roll over pole and cut formula unit and cable which characterized in that includes:
the annular shear type structural unit is formed by connecting shear type hinge units end to end; the scissor-type hinge unit is formed by hinging two folding rods in the middle of the folding rods; the annular shear type structure unit comprises an outer node, an inner node and a pivot node which are positioned at the end part of the shear type hinge unit;
the pull cables are connected among all internal nodes which are symmetrical by taking the center in the annular scissor-type structure unit as a center;
and the second-class guy cables are connected between the internal nodes and the external nodes of every two adjacent scissor hinge units in the annular scissor structure unit.
The annular scissor chain is formed by connecting 6 scissor hinge units end to end; the joints of the 6 scissor-type hinge units are respectively provided with a second-class inhaul cable; 3 pull cables of the same type are arranged at the internal nodes of the 6 scissor hinge units.
The included angle theta of the two limbs of the folding rod is 120 degrees.
Has the advantages that: compared with the prior art, the invention has the following advantages:
the traditional two-dimensional expandable structure is a mechanism, has no integral rigidity (cannot bear load action), and the member is basically a rigid rod piece, so that no prestress exists, the material utilization rate is low, and the integral weight is large. The formed members are very regular and convenient for modularization, and the structure presents high symmetry. In addition, the structure of the traditional two-dimensional expandable structure is not changed greatly before and after expansion, and more positive Poisson ratio effect is presented, while each node of the structural unit of the invention does linear motion along the radial direction around the central point of the structure in the expansion process, and synchronously expands or contracts, so that the structural unit presents obvious negative Poisson ratio effect, and the structural configuration is changed obviously, and the structural unit has good reliability and folding and expanding performance in the expansion process due to the existence of the inhaul cable.
The structural unit of the invention is completely different from the existing symmetrical deployable structural unit (straight rod, positive Poisson ratio), the proposed structural unit has integral structural rigidity in the deployed state, and the structure formed by periodic arrangement on a two-dimensional plane still has high symmetry and negative Poisson ratio effect of the basic unit.
Drawings
FIG. 1 is a schematic diagram of a fully contracted state of a highly symmetrical negative Poisson ratio structural unit based on a six-pair scissor unit and a inhaul cable.
FIG. 2 is a schematic diagram of a fully unfolded state of a highly symmetrical negative Poisson ratio structural unit based on a six-pair scissor unit and a inhaul cable.
FIG. 3 is a schematic state diagram of the high-symmetry negative Poisson ratio structural unit based on the six-pair scissor unit and the inhaul cable in the unfolding process.
FIG. 4 is a schematic diagram of the process of gradually expanding the highly symmetrical negative Poisson ratio structural unit based on the six-fold pair of scissor units and the inhaul cable from the fully contracted state.
Fig. 5a, 5b and 5c are schematic diagrams of a fully contracted state, an expanded process and a fully expanded state of a structure formed by periodically arranging high-symmetry negative poisson ratio structural units based on a six-pair scissor unit and a inhaul cable on a two-dimensional plane respectively.
In fig. 1, 2, 3, 4, and 5, thin solid lines each indicate a cable member, and thick solid lines each indicate a strut member. A, B, C, D, E, F in all figures respectively represent nodes located at the six edges of the hexagon, G, H, J, K, L, M respectively represent nodes located at the connecting lines of the geometric midpoint of the hexagon and the midpoints of the edges, and P, Q, R, S, T, U respectively represent nodes located at the connecting lines of the geometric midpoint of the hexagon and the vertices. Point O represents the geometric midpoint of the hexagon. The compression rods 101, 102, 103, 104, 105, 106, 111, 112, 113, 114, 115 and 116 belong to the same class of compression rods, the pull cables 201, 202 and 203 belong to the same class of pull cables, and the pull cables 211, 212, 213, 214, 215 and 216 belong to the second class of pull cables.
Detailed Description
The invention is further described with reference to the following examples and the accompanying drawings.
1. And connecting and classifying the components.
As shown in fig. 1, 2 and 3, the high symmetrical negative poisson ratio structural unit based on the folding rod scissor unit and the inhaul cable is disclosed. The folding rod scissor unit is illustrated by taking 6 pairs as an example and comprises 18 nodes, 6 pressing rod members and 9 pulling ropes.
The 18 nodes comprise 6 first-class nodes for connecting two rods and a cable, 6 second-class nodes for connecting two rods and two cables and 6 third-class nodes for connecting folding points of each pair of folding rods, wherein the 6 hinge nodes A, B, C, D, E and F are respectively positioned at the middle points of six edges of the hexagonal geometry in a counterclockwise sequence, the 6 hinge nodes G, H, J, K, L and M are respectively positioned on the connecting lines of the middle points and the middle points of the edges of the hexagonal geometry in a counterclockwise sequence, the 6 pivot nodes P, Q, R, S, T, U are respectively positioned on the connecting lines of the middle points and the top points of the hexagonal geometry in a counterclockwise sequence, and the hinge nodes and the pivot nodes are positioned in the radial direction of the hexagon.
In fig. 3, a thick line represents a press rod, 12 press rods, 12 press rod members are all folding rods, a folding point is located at the middle point of each press rod, an included angle θ between two sides of the folding point is 120 °, and the 12 press rods are respectively a press rod 101 connecting nodes A, P and G, a press rod 111 connecting nodes F, P and H, a press rod 102 connecting nodes B, Q and H, a press rod 112 connecting nodes A, Q and J, a press rod 103 connecting nodes C, R and J, a press rod 113 connecting nodes B, R and K, a press rod 104 connecting nodes D, S and K, a press rod 114 connecting nodes C, S and L, a press rod 105 connecting nodes E, T and L, a press rod 115 connecting nodes D, T and M, a press rod 106 connecting nodes F, U and M, and a press rod 116 connecting nodes E, U and G, wherein the press rods 101 and 111 are paired, a scissor-type hinge unit is formed by a pivot node P, and the press rods 102 and 112 are paired, a shear hinge unit is formed by a pivot node Q, a pair of pressure levers 103 and 113 is formed, a shear hinge unit is formed by a pivot node R, a pair of pressure levers 104 and 114 is formed, a shear hinge unit is formed by a pivot node S, a pair of pressure levers 105 and 115 is formed, a shear hinge unit is formed by a pivot node T, a pair of pressure levers 106 and 116 is formed, a shear hinge unit is formed by a pivot node U, the end points of 6 pairs of folding levers are connected with each other by hinge nodes, the 6 pairs of folding levers are rotationally symmetrical around the geometric midpoint of a hexagon, and one end of each of 12 folding levers is located at the midpoint of six sides of the hexagon.
In fig. 3, the thin lines represent guys, which are 9 guys in total, the guys include 3 first-class guys and 6 second-class guys located inside a hexagon, the 3 first-class guys are respectively a first-class guy 201 connecting nodes G and K, a first-class guy 202 connecting nodes H and L, and a first-class guy 203 connecting nodes J and M; the 6 second-class cables are respectively a second-class cable 211 for connecting the nodes A and H, a second-class cable 212 for connecting the nodes B and J, a second-class cable 213 for connecting the nodes C and K, a second-class cable 214 for connecting the nodes D and L, a second-class cable 215 for connecting the nodes E and M, and a second-class cable 216 for connecting the nodes F and G. In the fully contracted state, as in fig. 1, the 6 class two nodes G, H, J, K, L and M coincide at the geometric midpoint O of the hexagon. In the fully unfolded state, as shown in fig. 2, the two rods of each folding rod pair are overlapped, nodes a and H, nodes B and J, nodes C and K, nodes D and L, nodes E and M, and nodes F and G are overlapped and are respectively located at the middle points of the sides of the hexagon, and 6 pivot nodes are located at the six vertexes of the hexagon, as shown in fig. 3.
2. The geometric length of the member.
2l is used for representing the side length of the hexagon, as shown in fig. 1, 12 v-shaped pressure rods all have the same geometric length 2l, a break point is positioned on a perpendicular bisector of a connecting line of rod ends of the v-shaped pressure rods, the rod lengths on two sides of the break point are respectively l, and an included angle theta is 120 degrees. Under the complete contraction state, the 6 second-class stay ropes all have the same geometric length
All 3 cables of one type have the same geometric length of 0. As shown in FIG. 2, in the fully expanded state, the 6 second-class cables all have the same geometric length of 0, and the 3 first-class cables all have the same geometric length
3. The blanking length of the member.
The blanking length of the component is the length of the component when the processing is finished, and the component is in an unstressed state. The blanking length of each component is as follows:
wherein the content of the first and second substances,
the length of the blanking of the straight section of the pressure lever,
the material feeding lengths of the first class stay cable and the second class stay cable are respectively. All the compression bars are equal in length, all the inhaul cables of the first type are equal in length, and all the inhaul cables of the second type are equal in length.
4. And (5) assembling the structure.
Firstly, the straight sections of the pressure bar processed according to the blanking length are mechanically connected and assembled into a whole folding bar with an included angle of 120 degrees. The two nodes are connected through a pin shaft (only allowing relative rotation), and the three nodes are connected through a pivot. And (4) assembling the components together according to the connection relation, wherein the finally obtained structure is a hexagonal symmetrical deployable cable bar structural unit based on a hexagon.
5. The deployable nature of the structure.
The length of the first-type cable and the second-type cable can be changed through the driving device, so that the structure can be contracted and unfolded. When the first type of the stay cable is shortened to 0, the second type of the stay cable is extended to
The structure is fully collapsed with the 6 class two nodes G, H, J, K, L and M coinciding at the geometric midpoint O of the hexagon, as shown in FIG. 1. In addition, when the second type of cable is shortened to 0, the first type of cable is extended to 0
When the structure is fully deployed, nodes a and H, B and J, C and K, D and L, E and M, F and G coincide, as shown in fig. 2. In the moving process, all nodes move along the annular scissor structure units in the radial direction, all guys shorten/extend in the radial direction, each pair of folding rod units rotate around the pivot nodes mutually, the shapes of the folding rods are not changed, theta and alpha are kept unchanged and are respectively 120 degrees and 60 degrees, v is gradually increased from 30 degrees to 90 degrees in the unfolding process, and v is gradually decreased from 90 degrees to 30 degrees in the contraction process.
6. Periodic arrangement combination of structural units
A plurality of structural units are periodically arranged and combined, and in a contraction state, a type of node of one unit is taken as the geometric center of a hexagon where other units are located, and the structural units are combined in such a way, as shown in fig. 5 a. When one type of guy cable is shortened to 0 and the second type of guy cable is extended to 0 in the combined structure
The structure is fully collapsed and the class two nodes coincide at the geometric midpoint of the hexagon, as shown in fig. 5 a. In addition, when the second type of cable is shortened to 0, the first type of cable is extended to 0
When the structure is fully deployed, the rods coincide with the hexagons in which the structural units are located, as shown in figure 5 c. During the unfolding process, the end points of all the rod pieces move along the radial direction of the located hexagon.
The above examples are only preferred embodiments of the present invention, it should be noted that: it will be apparent to those skilled in the art that various modifications and equivalents can be made without departing from the spirit of the invention, and it is intended that all such modifications and equivalents fall within the scope of the invention as defined in the claims.
Claims (5)
1. The utility model provides a high symmetry negative poisson ratio constitutional unit based on roll over pole and cut formula unit and cable which characterized in that includes:
the annular shear type structural unit is formed by connecting shear type hinge units end to end; the scissor hinge unit is formed by connecting two folding rods in the middle of the folding rods in a pin joint manner; the annular shear type structure unit comprises an outer node, an inner node and a pivot node which are positioned at the end part of the shear type hinge unit;
the pull cables are connected among all internal nodes which are symmetrical by taking the center in the annular scissor-type structure unit as a center;
and second-class guys connecting the internal nodes and the external nodes of every two adjacent scissor hinge units in the annular scissor structure unit;
the included angle theta of the two limbs of the folding rod is 120 degrees.
2. The highly symmetric negative Poisson's ratio structural unit of claim 1, wherein the ring-shaped scissor structural unit is formed by connecting 6 scissor hinge units end to end; the joints of the 6 scissor-type hinge units are respectively provided with a second-class inhaul cable; 3 pull cables of the same type are arranged at the internal nodes of the 6 scissor hinge units.
3. The high-symmetry negative poisson's ratio structural unit of claim 1, wherein the lengths of the various members are:
wherein the content of the first and second substances,
to pressThe length of the two limbs of the rod,
、
the lengths of the first class stay cable and the second class stay cable are respectively; all the compression bars are equal in length, all the inhaul cables of the first type are equal in length, and all the inhaul cables of the second type are equal in length.
4. The high-symmetry negative Poisson's ratio structural unit of any one of claims 1-3, wherein the length of the first-type cable and the second-type cable is changed by a driving device to realize the contraction and expansion of the high-symmetry negative Poisson's ratio structural unit.
5. The high symmetry negative Poisson's ratio structural unit of claim 4, wherein when one type of cable is shortened to 0, the second type of cable is lengthened to 0
lThe symmetric negative poisson's ratio structural unit is fully contracted, with 6 internal nodes coinciding at the geometric midpoint of the hexagon; when the second type stay cable is shortened to 0, the first type stay cable is extended to 0
lWhen the structure is completely unfolded, the internal nodes are superposed with the external nodes; in the moving process, all nodes move along the annular scissor structure units in the radial direction, all guys shorten/extend in the radial direction, each pair of folding rod units rotate around the pivot nodes mutually, the shapes of the folding rods are not changed, theta and alpha are kept unchanged and are respectively 120 degrees and 60 degrees, gamma is gradually increased from 30 degrees to 90 degrees in the unfolding process, and gamma is gradually decreased from 90 degrees to 30 degrees in the contraction process.
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| CN202010073081.3A CN111139936B (en) | 2020-01-21 | 2020-01-21 | High-symmetry negative Poisson ratio structural unit based on folding rod shear type unit and inhaul cable |
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| CN111139936B true CN111139936B (en) | 2021-06-25 |
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| GB2455167A (en) * | 2007-09-04 | 2009-06-03 | Univ Malta | Bimetallic or bimaterial members and systems which exhibit negative Poisson's ratio |
| CN102605892A (en) * | 2012-03-08 | 2012-07-25 | 东南大学 | Movable structure based on folding-rod shearing-type unit |
| CN202611068U (en) * | 2012-03-08 | 2012-12-19 | 东南大学 | Dome structure of deployable cable pole |
| CN105297902A (en) * | 2015-10-23 | 2016-02-03 | 东南大学 | Foldable cable bar structural unit based on hexagonal geometry |
| CN106149150A (en) * | 2016-08-29 | 2016-11-23 | 香港理工大学 | A kind of negative poisson's ratio woven fabric and manufacture method |
| CN209667394U (en) * | 2019-03-29 | 2019-11-22 | 广西大学 | A kind of large space development agency |
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2020
- 2020-01-21 CN CN202010073081.3A patent/CN111139936B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2455167A (en) * | 2007-09-04 | 2009-06-03 | Univ Malta | Bimetallic or bimaterial members and systems which exhibit negative Poisson's ratio |
| CN102605892A (en) * | 2012-03-08 | 2012-07-25 | 东南大学 | Movable structure based on folding-rod shearing-type unit |
| CN202611068U (en) * | 2012-03-08 | 2012-12-19 | 东南大学 | Dome structure of deployable cable pole |
| CN105297902A (en) * | 2015-10-23 | 2016-02-03 | 东南大学 | Foldable cable bar structural unit based on hexagonal geometry |
| CN106149150A (en) * | 2016-08-29 | 2016-11-23 | 香港理工大学 | A kind of negative poisson's ratio woven fabric and manufacture method |
| CN209667394U (en) * | 2019-03-29 | 2019-11-22 | 广西大学 | A kind of large space development agency |
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