WO2000055439A2

WO2000055439A2 - Module for a space structure and a space structure

Info

Publication number: WO2000055439A2
Application number: PCT/GB1999/000637
Authority: WO
Inventors: Olivier Baverel
Original assignee: Coventry University
Current assignee: Coventry University
Priority date: 1999-03-03
Filing date: 1999-03-03
Publication date: 2000-09-21
Anticipated expiration: 2001-09-03
Also published as: WO2000055439A3; AU3264199A

Abstract

A module (10) for a space structure (28) comprises three elongate members (12a, 12b, 12c), each member having a first, free end (14a, 14b, 14c) and a second end (16a, 16b, 16c) connected at or adjacent said second end to one other of said members intermediate (18a, 18b, 18c) the ends of said one other member, thereby to form a triangle (26). Viewed from another aspect a space structure (28) comprises at least three elongate members (12a, 12b, 12c) interconnected with one another by way of a plurality of joints (18a, 18b, 18c) thereby to form a polygonal structure (26, 30, 42, 44...) each said joint comprising an interconnection of only two of said members.

Description

Module for a Space Structure and a Space Structure

The invention relates to a module for a space structure and to a space structure.

The geometries of the geodesic and tensegrities structures and their behaviour are well known. N problem with a standard geodesic structure is that the joints of the structure connect between six and twelve elements, so that the joints are complex and the jointing of the elements is expensive. Additionally, a variety of lengths of elements is used which results in a complex construction. The weakest part of such geodesic and tensegrities structures occurs at the joints, so that this is a limiting feature of the construction.

The present invention seeks to provide an improved module for a space structure and an improved space structure.

Accordingly, the present invention provides a module (10) for a space structure, the module (10) comprising at least three elongate members (12) interconnected with one another by way of a plurality of joints thereby to form a polygonal structure;

wherein each member (12) has a first, free end (14) and a second end (16) securely connected at or adjacent said second end to a location (18)On an adjacent one of said members (12) intermediate the ends of said one member (12).

A preferred form of module (10) has parameters L and λ where:

L is the length of one of said members (12), and

λ is the length of the side of the polygon formed by the module (10) along the said one of said members (12),

and the module (10) has a preselected ratio L:λ thereby to determine the shape of a structure formed from a plurality of said modules (10).

Advantageously, the module (10) has parameters L and λ where:

is the length of each said member (12), and

λ is the length of each side of the polygon formed by the module (10),

Accordingly, the present invention also provides a space structure comprising a plurality of modules (10) as claimed in any of the three immediately preceding paragraphs..

The polygon formed by the module may be regular or irregular.

In a preferred form of the invention the module has three elongate members and the polygon formed by the module is a triangle formed between three interconnected members.

Preferably, the elongate members are of substantially equal lengths. This gives the advantage of ease of manufacture and construction of the structure.

The formation of polygons, such as triangles, from the joining of the elongate members ensures that the space structure has a secure, rigid structure.

The external angle formed between two members at ajoint may be 10° to 170° orpreferably between 90° and l50°.

In a preferred form of module three members are provided and the external angle formed at each junction between the members is approximately 120° so that an approximately equilateral triangle is formed. For example, where it is desired to produce a space structure of an equilateral hexagon grid, the external angle between two elements will be 120°.

The present invention is further described hereinafter, by way of example only, with reference to the accompanying drawings, in which:

Figure la is a diagrammatic representation of a first preferred form of module according to the present invention for a space structure;

Figure lb is a representation of a part of a space structure comprising a plurality of modules of Figure la;

Figure 2a is a perspective view of a practical 3-dimensional form of the module of Figure la according to the present invention for a space structure;

Figure 2b is a representation of a part of a space structure comprising a plurality of modules of Figure 2a;

Figure 3 is a second form of module for a space structure;

Figure 4 is a representation of part of a space structure comprising a plurality of modules of Figure 3; and

Figures 5 to 19 show examples of structures according to the invention.

Referring firstly to Figure 1 a, this illustrates a preferred form of module 10 comprising three elongate members 12a, 12b, 12c which are conveniently rigidly connected to one another. Each of these members has a first, free end 14a, 14b, 14c. Each member has a second end 16a, 16b, 16c which is connected to an adjacent one of the other members at a position intermediate the ends of the other member. It will be appreciated that each member may be connected at a point adjacent to its end (rather than at its end) to one of the other members. The second end of member 12a connects with member 12b at a position 18b intermediate the ends of member 12b. The second end of member 12b connects with member 12c at a position 18c intermediate the ends of member 12c. The second end of member 12c connects with member 12a at a position 18a intermediate the ends of member 12a.

The result is a polygon in the form of a triangle formed by the members 12a, 12b, 12c with the sides of the triangle extended.

Each of the external angles α,, α₂, α₃ formed by the connections of the elongate members is preferably 120°, as a result of which the triangle formed by the connection of the three elongate members is an equilateral triangle 26. It will be appreciated that the external and internal angles may be varied, as illustrated below.

In Figure 1 a L is the length of each elongate member and λ is the length of the triangle sides.

In Figure lb, a part of a space structure 28 is shown which is composed of plurality of modules of Figure la. The free end of each module is connected to a further member of a like module intermediate the ends of the further member. By connecting a plurality of members in this manner, the space structure is formed, in which the members combine in a plurality of equilateral hexagons 30.

The arrangement shown in Figure lb will be generally flat where the members 12a, 12b and 12c abut one another. However, by arranging the members as shown in Figure 2a with each member lying on top of the adjacent member, a three-dimensional shape can be given to the module. Interconnecting a number of modules of the form shown in Figure 2a can then result in a structure which has a curved surface such as shown in Figure 2b where the structure is generally of a part cylindrical shape.

Each member lying on top of the adjacent member at the point of connection introduces an eccentricity E in the connection. The eccentricity E is the spacing between the longitudinal axes of interconnecting members at their point of interconnection and is a function of the diameter or thickness D of the members 12. With members of the same cross-section the eccentricity is equivalent to the thickness of the members (the diameter with members of the same circular cross-section). The eccentricity may also be reduced by suitable shaping of the members at the point of interconnection.

The modules of Figure 2a can be used to generate a relatively flat surface by inverting adjacent modules.

The members shown in Figure 2a are generally of circular cross-section. However, any suitable cross-section or shape may be used. Examples are rectangular, elliptical and oval. Members of different cross-sectional shapes maybe mixed in a module and adjacent modules may have members of different cross-sectional shapes. For example, one module may have members of a circular cross-sectional shape whilst an adjacent, connected module might have members of oval or rectangular cross-sectional shape.

Figure 3 shows a module 32 similar to that of Figure la comprising three elongate members 34a, 34b, 34c interconnected at positions 38a, 38b, 38c. In the embodiment shown in Figure 3 the external angles β,, β₂, β₃ between the elongate members are not all equal. The angle β_j is 135°, the angle β₂ is 90°, and the angle β₃ is 135°.

As can be seen from Figure 3, because the external angles of the triangle are not all identical, the sides have different lengths λj and λ₂.

Figure 4 shows a space structure 40 formed from modules as shown in Figure 3. The free end of each elongate member is connected to a further member of a like module intermediate the ends of the further member so that the space structure is formed. The interconnected triangle modules produce a larger structure of octagons 42, and squares 44.

It will be appreciated that the internal and external angles of the triangle of each module may be varied to provide different resulting space structures. Each of the external angles of the triangles may have a value in the range 90° to 170°, preferably 90° to 150°, depending on the ratio of the length L of each elongate member to the length λ of the triangle sides. The range of the external angles of the module may be proportional to or a function of λ although it will be appreciated that the external angles may be maintained constant while varying the length λ. One of the angles may also have a value in the range 10° to 90°.

The space structure as shown in Figures lb and 4 and other space structures formed from other modules which fall within the scope of the present invention may be formed without first forming the modules. A plurality of elongate members may be connected to one another in situ as the structure is constructed so that the triangles of the modules are formed in situ. When construction is carried out in this manner the angles between elongated members have to be set to the required value.

Using the hexagon grid of Figure lb a half cone structure can be created. This is effected by using several different values of λ with different L/E ratios. Only a few different values of λ with different L/E ratios are needed to generate an exact half cone. Examples of the basic cone structure that could be generated are shown in Figures 5 and 6 with Figure 5 showing the basic form of a 60° cone and Figure 6 showing the basic structure of a 120° cone.

Several cones may be joined together to create a multi-cone structure. The cones intersect along what is termed a hinge 49 formed from the elongate members so that at the intersection, the interconnecting elongate members of the two intersecting cones actually form parallelograms with one another. The shape^" of the hinge along its length may be parabolic, hyperbolic, elliptical or circular, depending on the number of cones which are interconnected and their angle of inclination with respect to one another.

Figure 7 shows one example of a structural hinge whilst Figure 8a shows an example of a structural hinge which joins two 60° cones together. The form of the resulting structure is shown in Figure 8b.

Figures 9a and 9b and Figures 10a and 10b show respectively the interconnection of three 120° cones and the interconnection of six 60° cones using the above described hinges. In the structures of Figures 7 to 10 small parallelograms 48 and large parallelograms 50 are used in order to form the hinges.

The structural hinge arrangement can be utilised to form a wide range of different connections so that cones, arches, open and straight ends can be formed. Figures 11, 12 and 13 show some of the possible arrangements of structural hinges based on the hexagonal arrangement shown in Figure lb. Figure 11 shows a structural arrangement for connecting five cones and two arches, Figure 12 shows a structural hinge arrangement for connecting four cones and two arches, and Figure 13 shows a structural hinge arrangement for connecting four cones and one arch.

Where a half cone shape on its own is generated, the structure is open and may be used to create a door or hole anywhere in a space structure. Figure 14, for example, shows an arrangement of two 120° cones with a 120° open end. The cones intersect at a hinge 60 whilst at the open end of the structure the elongate members 64 which would otherwise have projecting free ends are connected to additional elongate members 66. As a result, the free ends are not left protruding.

Figure 15 shows part of an open end structure.

Figure 16a shows the detailed structure of a 60° cone with a 60° open end whilst Figure 16b is a diagrammatic representation of the final structure covered with a suitable material.

Figure 17 shows a modified form of elongate member 12¹ which is formed by two parallel elongate element, 82 which are interconnected by a number of bracing members or braces 84 to provide rigidity to the member 12¹. Although the braces 84 are shown in Fig 17 as extending generally perpendicular to the elements 80, 82 they can extend transversely of the elements at any suitable angle.

Figure 18 is an end elevation of the member of figure 17. Figure 19 shows how several members 12¹ are interconnected with the adjacent upper elements of the members being inter-connected and the adjacent lower elements of the members also being inter-connected.

Whilst the modules which are illustrated in Figures la, 2a and 3 and described above use three members to form a triangular structure, it will be appreciated that the number of members may be varied in order to form a polygonal structure. Thus, the module may form a square, rectangle, pentagon or hexagon or the like instead of the illustrated triangle, using the desired number of members.

In addition, whilst the polygon may be a regular polygon, it will also be appreciated that by varying the angles α within a module the polygon which is formed may be an irregular polygon. Thus a triangular module may have two angles α the same and one different or three different angles a. Thus the length λ can be varied within each module to provide irregular shaped modules, as can one or more of the angles a, the eccentricity E and the diameter or thickness D of each member, to vary the offset of each member from the plane of the module.

For a three-dimensional structure as described above, using a single type of module the shape of the ultimate structure is self generating and may be defined by selected parameters of the module, these being the angle α, the length λ, the length L of each member and the eccentricity E. The eccentricity E is determined by the thickness or diameter D of each member and so may be indirectly defined in terms of D.

The ratio L:λ can be used to predict or predetermine the shape of the structure to be formed from the modules. By presetting this ratio alone or in combination with any of E, D and/or L the shape of the structure to be formed can be preset.

The eccentricity or spacing E between the longitudinal axes of interconnecting members at their point of interconnection also, with the length L of the members, determines or influences the curvature of the structure. A structure using the above-described modules has many degrees of freedom and will find its own shape which tends to be a shape with minimum potential energy. The interconnections between the modules may be made flexible or may include some damping provision which renders the structure to some extent flexible and therefore resistant to earthquake damage.

It will be appreciated that by using modules of different types, for example where the parameters are varied, a number of differently curved surfaces can be interconnected in order to provide a structure having at least two or more different surface curvatures. As has been described above, the different surfaces are interconnected by structural hinges and the curvatures of the different surfaces can be changed by varying the selected parameters as described above. Thus, a structure can be provided which has a number of arrays of modules interconnected by structural hinges, each array of modules having its own predetermined surface curvature.

The invention has many different applications and a structure built using modules according to the present invention could be used as a temporary or permanent shelter.

Geometrical structures such as arches, inclined arches, cones, flat surfaces, domes, polyhedra and free shapes could be constructed with, for example, plastics sheeting used to cover the structure.

The interconnections of the modules and/or of the individual members of a module may be chosen to suit a particular structure and may be flexible or allow pivoting or relative rotation to a desired extent of the modules and/or of the members.

Claims

1 A module (10) for a space structure, the module (10) comprising at least three elongate members (12) interconnected with one another by way of a plurality of joints thereby to form a polygonal structure;

wherein each member (12) has a first, free end (14) and a second end (16) securely connected at or adjacent said second end to a location (18) on an adjacent one of said members (12) intermediate the ends of said one member (12).

2 A module (10) as claimed in claim 1 wherein the module has parameters L and λ where:

L is the length of one of said members (12), and

3 A module (10) as claimed in claim 1 wherein the module has parameters L and λ where:

L is the length of each said member (12), and

λ is the length of each side of the polygon formed by the module (10),

and the module (10) has a preselected ratio L:λ thereby to determine the shape of a structure formed from a plurality of said modules (10). 4 A module (10) as claimed in claim 2 or 3 wherein the module has a parameter α where:

α is an external angle formed between two interconnected elongate members of the module (10),

and the shape of a structure formed from a plurality of said modules (10) is further determined by preselecting α.

5 A module (10) as claimed in claim 4 wherein the range of each external angle is proportional to the ratio L:D where D is the thickness of the members (12) of the module (10).

6 A module (10) as claimed in claim 4 or 5 wherein the range of each external angle is90° to l70°.

7 A module (10) as claimed in claim 6 wherein the range of each external angle α is90° to 150°.

8 A module (10) according to any of claims 2 to 7 wherein the longitudinal axes of at least two interconnected members (12) are spaced apart at the interconnection of the two members.

9 A module (10) according to claim 8 wherein the longitudinal axes of each pair of interconnected members (12) are spaced apart at the interconnection of the members thereby to create a three dimensional module (10) for forming three dimensional surfaces of the structure.

10 A module (10) as claimed in claim 8 or 9 wherein the module has a parameter E where: E is the eccentricity or spacing between the longitudinal axes of interconnecting members (12) at their point of interconnection (18),

and the shape of a structure formed from a plurality of said modules (10) is further determined by preselecting E.

11 A module (10) as claimed in any of claims 2 to 10 wherein the ratio of L:λ is the same for each said member (12) of the module (10).

12 A module (10) according to any of the preceding claims wherein the polygon formed by the module (10) is a regular polygon.

13 A module (10) according to any of the preceding claims wherein the polygon formed by the module (10) is an irregular polygon.

14 A module (10) according to any of the preceding claims wherein the polygon is a triangle.

15 A module (10) according to any of the preceding claims wherein each said member (12) comprises two parallel, spaced apart elongate elements (80, 82) interconnected by a plurality of bracing members (84).

16 A module (10) according to any of the preceding claims wherein the members (12) are of substantially the same length.

17 A module (10) according to any preceding claim wherein the external angle formed at each junction between the members (12) is approximately 120° to form an equilateral triangle.

18 A space structure comprising a plurality of modules (10) as claimed in any of the preceding claims. 19 A space structure as claimed in claim 18 wherein:

each said module (10) forms a regular polygon in the form of a triangle;

and the free end of each said member is connected to a further member of a like module (10) intermediate the ends of said further member thereby to form an equilateral hexagonal grid.

20 A space structure according to claim 18 wherein the external angle formed between members (12) at a joint is between 10° and 170°.

21 A space structure according to claim 20 wherein the external angle formed between members at a joint is between 90° and 150°.

22 A space structure according to claim 21 wherein the external angle formed at each junction between the members is approximately 120° to form an equilateral hexagonal grid

23 A space structure as claimed in claim 18 wherein:

each said module (10) forms an irregular polygon in the form of an equilateral triangle;

and the free end of each said member is connected to ^"a further member of a like module (10) intermediate the ends of said further member thereby to form an equilateral octagonal grid.

24 A space structure as claimed in any of claims 18 to 23 wherein:

the surface of said structure is formed by a plurality of arrays of said modules (10);

and each array has a predetermined surface curvature.

25 A space structure as claimed in claim 24 wherein the surface curvatures of the arrays are different. 26 A space structure as claimed in claim 24 or 25 wherein adjacent arrays are interconnected by at least one structural hinge (49) formed by a further array of said modules (10).

27 A space structure as claimed in claim 26 wherein the modules (10) of said further array of said modules are of non-triangular polygonal form.

28 A space structure as claimed in any of claims 18 to 23 having a plurality of arrays of said modules (10) interconnected by at least one structural hinge formed by a further array of said modules (10);

wherein the modules (10) of said further array of said modules are of non-triangular polygonal form.

29 A space structure as claimed in claim 27 or 28 wherein said non-triangular polygonal modules are of parallelogram form.

30 A space structure according to any of claims 24 to 29 and comprising portions of the surface of a plurality of cones, intersecting on structural hinges.

31 A space structure according to any of claims^" 18 to 23 and defining a portion of the surface of a cone.

32 A space structure according to any of claims 18 to 31 wherein the shape of the structure is determined by the following parameters of each module (10):

the length λ of each side of the polygon formed by each module (10);

and the length L of each elongate member. 33 A space structure according to claim 32 wherein the shape of the structure is further determined by at least one of the following parameters of each module (10):

the external angle α formed between two interconnected elongate members of each module (10);

the eccentricity or spacing E between the longitudinal axes of interconnecting members (12) at their point of interconnection (18);

and the cross-sectional shape of the elongate members.