WO2014170651A1

WO2014170651A1 - Deployable structure

Info

Publication number: WO2014170651A1
Application number: PCT/GB2014/051162
Authority: WO
Inventors: Zhong You; Jonathan HO
Original assignee: Oxford University Innovation Ltd
Current assignee: Oxford University Innovation Ltd
Priority date: 2013-04-19
Filing date: 2014-04-14
Publication date: 2014-10-23
Anticipated expiration: 2015-10-19
Also published as: GB201307114D0

Abstract

A deployable structure, comprising: a first construction unit comprising a spacing module and a first flange module, wherein: the spacing module comprises first, second, third and fourth sheet units that are hinged together; the first flange module comprises fifth, sixth, seventh and eighth sheet units that are hinged together; and the spacing module and first flange module are connected together by hinges in such a way as to be switchable by rotation about the hinges between: a storage state in which the first to eighth sheet units are substantially coplanar; and a deployed state in which the first flange module is compressed in two orthogonal directions relative to the storage state.

Description

DEPLOYABLE STRUCTURE

The present invention relates to a deployable structure configurable for use for example as a packing material or civil engineering structure. The deployable structure provides a level of rigidity when in use but can be folded away when not in use for ease of transport or storage. The deployable structure may form a two- or three-dimensional grid for example, in the deployed state.

Thin-walled deployable structures are known that conform to a branch of origami known as rigid origami, in which flat sheets are connected by hinges. These sheets must remain completely rigid at all times, but can rotate relative to each other around the hinges. Restricting the geometry to perfectly rigid sheets allows rigid origami to be applied to engineering applications using stiff materials such as metals, plastics and composites which have only negligible deformation under expected conditions of loading.

Previous work on tubular thin-walled structures (Zhang, X.W., Su, H. and Yu, T.X. (2009), "Energy

Absorption of an axially crushed square tube with a buckling initiator", International Journal of Impact Engineering, vol. 36, issue 3, 402-417) has mainly focused on the energy absorption of polygonal tubes during deformation. It has been reported that by pre-folding a tube according to certain origami patterns, the failure mode of a tube can be altered (Ma, J., Le, Y. and You, Z. 2010, "Axial Crushing Tests of Thin-Walled Steel Square Tubes with Pyramid Patterns", 51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, DVD-ROM, Reston, VA: AIAA, 2010).

Individual tubes can resist loads or impacts effectively along their axial direction, and placing an array of such tubes may produce an impact resistant mat. However, positioning tubes near to each other to cover a wider area would lead to interference between adjacent tubes.

Cardboard packaging boxes are often partitioned by grids to separate the consumer goods inside. These grids can be formed from flat-packed elements. Figure 1 illustrates an example of such a grid, which is formed by sliding together cardboard strips 102 and 104, each of which have pre-cut slots 106 half the height of the strip, and which meet with a slot on the intersecting strip. This type of grid lacks rigidity, meaning only small loads can be applied to the grids: all the slots in a strip are cut on the same side so there is no restraint for the continuous part of the strip, which allows the strip to collapse sideways under any significant load. Attempting to use alternating slots significantly complicates the assembly process and requires the strips to be flexible to allow them to be interlaced.

Grid structures for providing structural stiffness in engineering applications are known. Such grids may be provided with flat or slightly curved surfaces attached above and below to provide so-called laminated or sandwich panels, which combine high strength and low weight. These are used particularly in mechanical engineering applications such as aerospace where a high strength-to-weight ratio is required. However, such grid structures can be voluminous, which can make storage and transport difficult and inhibits the use of such structures in the general construction industry and/or for use in building temporary structures. Rigid origami structures that fold down completely in the axial direction, such as cylindrical folding polyhedra, are known. However, such structures cannot easily be assembled laterally to form a grid and cannot support any axial loads.

It is an object of the invention to provide a deployable structure that addresses at least one of the problems with the art discussed above.

According to an aspect of the invention, there is provided a deployable structure, comprising: a first construction unit comprising a spacing module and a first flange module, wherein: the spacing module comprises first, second, third and fourth sheet units that are hinged together; the first flange module comprises fifth, sixth, seventh and eighth sheet units that are hinged together; and the spacing module and first flange module are connected together by hinges in such a way as to be switchable by rotation about the hinges between: a storage state in which the first to eighth sheet units are substantially coplanar; and a deployed state in which the first flange module is compressed in two orthogonal directions relative to the storage state.

Thus, a deployable structure is provided that can be switched between a storage state in which all of the constituent sheet units are folded flat (substantially parallel with each other) and a deployed state in which a grid element can be formed with a finite height. The grid element, corresponding to a single construction unit, can be repeated to provide two- or three-dimensional grid structures. Appropriate selection of the materials used for the sheet units and/or the hinges, of the dimensions of the individual construction units, and of the way in which the construction units are repeated, can provide deployable structures with a wide range of properties for use in different situations.

The deployable structure, whether consisting of a single construction unit or many, comprises a single unit and the switching can be performed merely by rotating the constituent sheet units about hinges that connect the sheet units, which can be achieved easily because the rotations are interrelated. Typically, pulling on a small number of sheet units (e.g. two) in appropriate directions will be sufficient to cause the structure to switch from the storage state to the deployed state. It is not necessary for example to slot or otherwise connect multiple, separate elements together in order to switch the structure into the deployed state. The deployable structure of the invention is therefore easier and/or quicker to deploy than such a system.

In an embodiment, the flange modules are arranged to fold substantially flat in the deployed state. When folded flat the flange modules constrain effectively the lateral displacement of the sheet units of the spacing module and help to provide strength against compression perpendicular to the coplanar normals of the first to fourth sheet units. This compressive strength is particularly high where both first and second flange modules are provided, which can constrain the spacing module sheet units on both sides.

The sheet units of the spacing module can comprise single planar sheets, which hinge about parallel axes such that in the deployed state the sheet units have coplanar normals. Alternatively, each of the sheet units of the spacing module may be formed from multiple sub-sheets (e.g. 2, 3, 4 or more sub-sheets). The multiple sub-sheets may be hinged together, for example along lines that are perpendicular to one of the orthogonal directions of compression of the first flange module in the deployed state, such that rotation about these hinges during deployment causes the first to fourth sheet units to be compressed parallel to the one of the two orthogonal compression directions. In an embodiment, the compression of the spacing module thus caused is proportionately (i.e. as a proportion of the original size of the spacing module) less than the compression of the first flange module. Thus, each of the sheet units of the spacing module can be formed from sub-sheets that are not parallel to each other in the deployed state and thus tend to provide a greater degree of cushioning or springiness in the direction of compression. Deployable structures formed using such spacing modules can be used in applications that require such properties, such as for packaging delicate objects.

In an embodiment, the deployable structure is configured for use as a packaging material. In such an embodiment, the deployable structure may be configured to form a planar grid in the deployed state with the interstices of the grid being suitable for partitioning packed products, such as bottles.

A kit for forming a partition element may be provided that comprises one or more deployable structures according to an embodiment. The kit may further comprise one or more outer sheet elements for attaching to one or more outer surfaces of the deployable structure when the structure is in the deployed state. The partition element may be used for constructing a floor, a ceiling and/or a wall, for example. The kit may comprise a deployable structure that is configured to form a planar grid in the deployed state with the one or two outer sheet elements being provided for attachment to one or both of the outer surfaces of the planar grid (i.e. the outer surfaces parallel to the plane of the grid).

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which corresponding reference symbols represent corresponding parts, and in which:

Figure 1 depicts a prior art grid structure formed from slotted strips;

Figure 2 is a side view of a sheet comprising a Miuri-Ori folding pattern;

Figure 3 is a perspective view of the sheet of Figure 2 in a partially deployed state;

Figure 4 is a perspective view showing how two sheets of the type shown in Figures 2 and 3 can be connected together to form a folding mechanism;

Figure 5 is a perspective view showing the folding mechanism formed after connection of the sheets illustrated in Figure 4;

Figure 6 illustrates a sequence of folding of a folding mechanism of the type shown in Figure 5; Figure 7 depicts variables for defining the geometry of the folding mechanism of Figures 5 and 6; Figure 8 is a side view of the folding mechanism of Figures 5-7 in the unfolded state;

Figure 9 is a top view of the folding mechanism of Figures 5-8 in the fully folded state; Figure 10 depicts side and top views of the folding mechanism of Figures 5-9 in a partially folded state;

Figure 11-14 illustrate how the folding mechanism of Figures 5-9 can be split horizontally and connected to vertical sheet units in order to form a deployable structure having vertical rigidity in the deployed state;

Figure 15 depicts the deployable structure of Figure 14 in a partially deployed state;

Figure 16 depicts the deployable structure of Figures 14 and 15 in a fully deployed state;

Figure 17 is a side view of the deployable structure showing characteristic dimensions;

Figure 18 illustrates how individual construction units can be connected together to form a linear deployable structure extending along Y;

Figure 19 illustrates how individual construction units can be connected together to form a linear deployable structure extending along X;

Figure 20 illustrates how construction units can be connected together to form a square, planar grid with diagonal walls;

Figures 21 illustrates how strips of sheet units can be connected together to form a deployable structure that, in the deployed state, forms a square, planar grid with walls that are parallel to the edges of square;

Figure 22 depicts the planar grid of Figure 21 in a partially deployed state;

Figure 23 depicts the planar grid of Figure 22 in the fully deployed state;

Figure 24 is a side view of a deployable structure that forms a three-dimensional grid in the deployed state and which is formed from construction units having both first and second flange modules;

Figure 25 is a perspective view depicting the deployable structure of Figure 24 in a partially deployed state;

Figure 26 is a perspective view depicting the deployable structure of Figure 24 in the fully deployed state;

Figure 27 is a side view of a deployable structure that forms a three-dimensional grid in the deployed state and which is formed from construction units having a first flange module but not a second flange module;

Figure 28 is a perspective view depicting the deployable structure of Figure 27 in a partially deployed state;

Figure 29 is a perspective view depicting the deployable structure of Figure 27 in the fully deployed state;

Figure 30 depicts how strips of sheet units can be connected together to form a deployable structure suitable for use as a packaging construction for partitioning products;

Figure 31 depicts the deployable structure of Figure 30 in a deployed state ready to receive products; Figure 32 depicts a kit for forming a partition element;

Figure 33 depicts a partition element formed using the kit of Figure 32;

Figure 34 is a side view of a deployable structure comprising spacing modules formed from sheet units that each comprise two sub-sheets;

Figure 35 is a side view of a deployable structure comprising spacing modules formed from sheet units that each comprise three sub-sheets.

In an embodiment, a deployable structure is provided that folds down to a non-zero height, with out- of-plane sheets providing compression resistance against vertical loads. In an embodiment, the structure is repeatable along the in-plane directions, to form a grid which is capable of covering a wider area. For storage or transportation, the structure folds away flatly into the vertical plane.

In an embodiment, the deployable structure comprises a folding mechanism combined with a grid of vertical walls (referred to as sheet units of spacing modules in the detailed description below). The folding mechanism may be configured to have a single degree of freedom, with interdependence of the fold or hinge lines (also referred to as axes of operation of the hinges) allowing the whole mechanism to fold flat simultaneously. The grid of vertical walls provides resistance against vertical loads when restrained by the folding mechanism. In an alternative embodiment the vertical walls may be formed from sub-sheets that can hinge relative to each other to form a concertina-like, ziz-zag pattern, which provides resilience or

"springiness", thereby providing a mechanism for controllably cushioning vertical loads. The folding mechanism constrains the grid to a pre-determined shape when folded out and allows it to be easily folded away due to the single degree of freedom.

A Miura-Ori (literally, "Miura fold") is a rigid fold pattern development by Miura (Miura, K. (1993), "Map Fold a La Miura Style, Its Physical Characteristics and Application to the Space Science", Research of Pattern Formation, pp. 77-90). Miura-Ori patterns are examples of folding mechanisms with a single degree of freedom and can be folded and unfolded in a simple and convenient manner. For example a geographical map folded according to a Miura-Ori pattern can be deployed simply by pulling on opposite corners, in contrast to conventional orthogonally folded maps that require a complex sequence of movements to unfold. Furthermore, once unfolded the non-right-angled corners of a Miuri-Ori map are much more stable and less prone to folding "inside out" .

In an embodiment, a Miuri-Ori pattern is used as the basis for the folding mechanism of the deployable structure. A particular example is explained with reference to Figures 2-5.

Figure 2 illustrates a plurality of sheet units 201 connected together to form a folding mechanism 200 embodying a Miuri-Ori pattern. The sheet units 201 are connected together by "mountain" hinges (hinging out of the page) or "valley" hinges (hinging into the page). In the configuration of Figure 2 the mechanism is flat, with all of the sheet units 201 lying in the same plane. Figure 3 illustrates the mechanism 200 of Figure 2 after folding along the hinges to form a non-coplanar structure. A mirror image 202 of the mechanism 200 can be connected to the mechanism 200 along the marked hinges 1, 2, 3 and 4, such that hinge 1 is connected to hinge Γ, hinge 2 is connected to hinge 2', hinge 3 is connected to hinge 3', and hinge 4 is connected to hinge 4'. This process is illustrated in Figure 4, with the resulting mechanism 210 being shown in Figure 5.

The mechanism 210 of Figure 5 can fold completely flat to form a quadrilateral grid in the flattened condition via the sequence shown in Figure 6. The geometry is discussed in further detail below with reference to Figure 7 in which the Z direction is referred to as "vertical" or "out-of-plane" and the X and Y directions are referred as "horizontal" or "in-plane" directions.

A fold angle Θ may be defined as the angle of inclination of the rigid sheets from the horizontal, as shown in Figure 7. Thus, θ = 0 degrees for the fully deployed state (horizontally flat) and Θ = 90 degrees for the undeployed state (vertically flat). Angles between 0 and 90 degrees represent partially deployed states. Since in this example the grid structure is symmetric about the central horizontal plane, Θ is the same whether measured to the upper or lower half of the mechanism; also, due to the geometry, whatever value Θ takes, all sheets of the mechanism are at that time inclined at the same value of Θ. The variables shown in Figure 7 can be divided into three categories. Firstly, there are the pre-determined parameters (a, b, c, and a), which are set by the starting geometry of the fold pattern and do not vary during deployment. Secondly, there is the fold angle, Θ, which is the independent variable, and whose value varies between 90 degrees and 0 degrees as the mechanism is deployed. Finally, there are the dependent variables (w, I, m, h and φ ), which are related to the independent variable by equations discussed below.

Figure 8 depicts a side view of the mechanism of Figure 5 in the fully undeployed state. In this state, the width w = 0, and the height h_u takes the value of the fixed variable c. The length /„ is given by the fixed variable a, and is the maximum value that / can take.

Figure 9 depicts a top view of the mechanism of Figure 5 in the fully deployed state. In this state, φ = φ_ά = a = φ^ . The length of the mechanism is given by l_d = a cos^ . Therefore, Id is the smallest value that / can take.

Figure 10 depicts side and top views of the mechanism of Figure 5 in a partially deployed state. Here, the fold angle Θ can take various values and the height of the grid varies sinusoidally with Θ according to h = c sin Θ, giving h = 0 at Θ = 0 degrees and h = c at Θ = 90 degrees. The length / and width w are given by the following equations: COS Θ

I ⁽I cos φ = a cos arcsin

COS Θ

w = a sm φ = a m axcsm— ,

i / -÷ sin² Θ

Thus, the height, length and width can be determined for any angle of deployment Θ as a function of the fixed variables of the undeployed pattern a, b, c and a. The mechanism can thus be designed specifically to provide a desired size and shape when deployed.

The present inventors have recognised that the mechanism of Figure 5 can be used as the basis for a deployable structure that, neglecting the finite thicknesses of the sheet units that make up the structure, can be folded completely flat in a "storage state" and can be folded into a structure having a finite thickness and, optionally, substantial compressive strength in a "deployed state". An example of how this can be achieved is described below with reference to Figures 11-15.

Figure 11 is a schematic view of mechanisms 200 and 202 comprising Miuri-Ori patterns similar to those depicted in Figure 4 for example. These mechanisms can be split along the central horizontal mirror plane as shown in Figure 12 to yield strips 204-207. The strips 204-207 are then connected together by vertical sheet units 301-304 which are connected together by hinges to form the two structures shown in Figure 13. These two structures are then connected together along the hinges marked "C" to form the deployable structure 800 shown in Figure 14. The structure 800 is the same as the structure 200 shown in Figure 5 except for the vertical sheet units 301-304. Figure 14 shows the structure 800 in the fully undeployed state. Figure 15 shows the same structure 800 in a partially deployed state. Figure 16 shows the same structure 800 in a fully deployed state with the sheet units of first and second "flange modules" (discussed below) folded flat (horizontal in the orientation shown).

The structure 800 may be described as being built up from two construction units 802 and 804 each comprising a spacing module and first and second flange modules. The spacing module comprises a first sheet unit 301, a second sheet unit 302, a third sheet unit 303 and a fourth sheet unit 304 (referred to previously as the vertical sheets 301-304 because they are parallel to Z in the orientation depicted in Figure 7). In the embodiment shown, the first to fourth sheet units are squares. In other embodiments different shapes may be used, such as rectangles. The first flange module comprises a fifth sheet unit 305, a sixth sheet unit 306, a seventh sheet unit 307 and an eighth sheet unit 308. The second flange module comprises a ninth sheet unit 309, a tenth sheet unit 310, an eleventh sheet unit 311 and a twelfth sheet unit 312. In an embodiment, the second flange module is provided on a side of the spacing module opposite to the first flange module. In an embodiment, the second flange module is a mirror image of the first flange module about a horizontal plane. In the embodiment shown the flange module sheet units are parallelograms having non-orthogonal sides.

In an embodiment, the hinges of the spacing module are parallel (i.e. have parallel axes of operation).

In an embodiment, the sheet units 305-308 of the first flange module are hinged together. In an embodiment, the sheet units 309-3012 of the second flange module are also hinged together. In an embodiment, the hinges of the first flange module are parallel (i.e. have parallel axes of operation) to each other. In an embodiment, the hinges of the second flange module are also parallel (i.e. have parallel axes of operation) to each other.

The sheet units of the spacing module and of the first flange module are connected together by hinges in such a way as to allow switching between a storage state (corresponding to the "undeployed state" shown in Figure 14 for example) and a deployed state (with the flange modules flat for example, as shown in Figure 16). In an embodiment, the switching is achieved by simultaneous rotation about all of the hinges connecting together the sheet units of the spacing module and the first flange module and, where provided, the second flange module. In an embodiment, the positioning of the sheet units and hinges provides only a single degree of freedom (there is only one way the transition between the storage state and deployed state can be achieved and no other end states are possible).

In an embodiment, in the storage state the first to eighth sheet units 301-308 of the spacing and first flange modules (and, where provided, the sheet units of the second flange module) are substantially coplanar, as shown in Figure 14. In an embodiment, in the deployed state the first to fourth sheets 301-304 of the spacing module lie in planes having coplanar normals (i.e. normals that lie in the same plane; in the example shown this is a horizontal plane). At least two of the first to fourth sheet units 301-304 are non-parallel in the deployed state. In the example shown, the first and third sheet units 301,303 are parallel to each other and the second and fourth sheet units 302,304 are also parallel to each other (but not parallel to the first and third sheet units 301,303).

In an embodiment, in the deployed state the first flange module is compressed (i.e. extends over a smaller distance) in a direction perpendicular to the plane of the coplanar normals (i.e. along the vertical direction in the orientation shown) relative to the storage state. This direction represents one of two orthogonal directions in which the first flange module is compressed when switching from the storage state to the deployed state (the other direction being the horizontal direction in the plane of the sheet units in the storage state, in the orientation shown). In an embodiment, the first flange module (and/or, where provided, the second flange module) is completely flat (to within the thickness of the sheet units 305-308) in the deployed state. In other embodiments, the first flange module (and/or, where provided, the second flange module) is not completely flat in the deployed state.

The hinges of the construction unit according to an embodiment will now be described in further detail with reference to Figure 15. In the embodiment shown, the spacing module hinges are as follows. The first sheet unit 301 is connected to the second sheet unit 302 by (i.e. along) a first hinge 601. The second sheet unit 302 is connected to the third sheet unit 303 by a second hinge 602. The third sheet unit 303 is connected to the fourth sheet unit 304 by a third hinge 603. Finally, the fourth sheet unit 304 is connected back to the first sheet unit 301 by a fourth hinge 604. The axes of operation of all of the first to fourth hinges 601-604 may be parallel to each other in this embodiment (throughout the range of movement from the storage state to the deployed state).

In the embodiment shown, the first flange module hinges are as follows. The fifth sheet unit 305 is connected along a fifth hinge 605 to the sixth sheet unit 306. The sixth sheet unit 306 is connected along a sixth hinge 606 to the seventh sheet unit 307. The seventh sheet unit 307 is connected along a seventh hinge 607 to the eighth sheet unit 308. Finally, the eighth sheet unit 308 is connected along an eighth hinge 608 back to the fifth sheet unit 305. Again, the axes of operation of all of the fifth to eighth hinges 605-608 may be parallel in this embodiment (throughout the range of movement from the storage state to the deployed state).

In the embodiment shown, the hinges connecting the first flange module to the spacing module are as follows. The fifth sheet unit 305 is connected along a ninth hinge 609 to the first sheet unit 301. The sixth sheet unit 306 is connected along a tenth hinge 610 to the second sheet unit 302. The seventh sheet unit 307 is connected along an eleventh hinge 611 to the third sheet unit 303. The eighth sheet unit 308 is connected along a twelfth hinge 612 to the fourth sheet unit 304. The axes of operation of all of the ninth to twelfth hinges 609-612 may be perpendicular to the axes of operation of the first to fourth hinges 601-604. The axes of operation of all of the fifth to eighth hinges 605-608 may be at an oblique angle relative to the axes of operation of the first to fourth hinges 601-604. In an embodiment the oblique angle is 45 degrees, which results in the construction unit grid forming square cells when viewed along the Z-axis. In such an embodiment, the first and third sheet units 301,303 are perpendicular to the second and fourth sheet units 302, 304 in the fully deployed state.

The configuration of hinges may satisfy one or more of the following conditions: the axes of operation of the first 601, fifth 605, ninth 609 and tenth 610 hinges intersect at a first point A; the axes of operation of the second 602, sixth 606, tenth 610 and eleventh 611 hinges intersect at a second point B; the axes of operation of the third 603, seventh 607, eleventh 611 and twelfth 612 hinges intersect at a third point C; the axes of operation of the fourth 604, eighth 608, ninth 609 and twelfth 612 hinges interest at a fourth point D. In the embodiment shown all of these conditions are satisfied.

Figure 17 is a side view of the deployable structure 800 of Figures 14-16 illustrating the example geometry. Relative to the geometry described with reference to Figures 7-10 above, Figure 17 introduces a new dimension, d, denoting the vertical separation of the two halves of the mechanism of Figures 7-10, also referred to as the height of the first to fourth sheet units 301-304 of the spacing modules. When the flange modules are configured to fold completely flat in the fully deployed state, the dimension d will define the vertical height of a single layer of the deployed structure (neglecting sheet thicknesses).

In an embodiment, any number of the construction units described above may be connected together to form a deployable structure of the desired size and/or with the desired mechanical properties. In an embodiment, the construction units are connected together at hinges such that all of the spacing modules and flange modules of the construction units are switchable in unison with each other, by rotation about the hinges, between the storage state and the deployed state. In the example illustrated in Figure 15 two construction units 802 and 804 are connected to each other at hinges of the respective spacing modules of the two construction units 802,804. In particular, the first construction unit 802 is connected to the second construction unit 804 by the second hinge 602 of the first construction unit 802 and the fourth hinge of the second construction unit 804.

In an embodiment, a linear, "in-plane" arrangement of construction units may be obtained by connecting a first construction unit to a set of one or more "in-plane" construction units which are configured such that the construction units form a line extending in a direction parallel to the plane of the coplanar normals of the first to fourth sheet units 301-304 (the horizontal or X-Y plane in the orientation depicted). The embodiment of Figure 15 is an example of such an arrangement with just two construction units, connected together along the Y-axis. Figure 18 shows the same arrangement extended further to include four construction units. A linear in-plane arrangement may also be formed by connecting construction units together along the X direction as shown in Figure 19.

In an embodiment, a planar arrangement of construction units is formed by combining two or more of the linear, in-plane arrangements described above in parallel. For example two of the arrangements of Figure 15 could be connected together side-by-side by connecting the first construction unit 802 along the first hinge 601 to a corresponding first construction unit (not shown) along the third hinge of that unit, and by connecting the second construction unit 804 along a first hinge to a corresponding second construction unit (not shown) along the third hinge of that unit. Figure 20 illustrates an example of such an arrangement with four linear, in-plane arrangements, each comprising four construction units in a line, connected in parallel to form a planar grid of 25 cells. In the example shown, the oblique angle a is 45 degrees, which results in the square cells shown.

In the example of Figure 20, the grid lines run diagonally rather than parallel to the orthogonal sides of the overall grid (marked by dashed lines). A structure with grid lines that are parallel to the orthogonal sides can be constructed using strips of steadily increasing/decreasing size as shown in Figure 21-23. Figure 21 depicts two strips 902 comprising two spacing module sheet units, two strips 904 comprising four spacing module sheet units, two strips 906 comprising six spacing module sheet units, and two strips 907 comprising seven spacing module sheet units, all in position ready to be connected along the closest approaching hinges to form the partially deployed, deployable structure 800 shown in Figure 22. Figure 23 illustrates the same employable structure 800 when fully deployed.

In an embodiment, the deployable structure can be built up by adding one or more construction units "out-of-plane" to a first construction unit, so as to form a stack extending along Z (i.e. in a direction perpendicular to the plane of the coplanar normals of the first to fourth sheet units 301-304).

In an embodiment, a three dimensional grid is formed by repeating a planar grid 1002 in the Z direction. In an embodiment, this is achieved by forming a mirror image of the planar grid 1002 about a plane perpendicular to Z that passes throughout the outermost hinges of the flange modules (indicated by arrows 1000). An example of such an arrangement is illustrated in Figures 24-26 with three planar grids 1002. Figure 24 is a side view of the deployable structure 800. Figure 25 is a perspective view of the deployable structure 800 in a partially deployed state. Figure 26 is a perspective view of the deployable structure 800 in the fully deployed state. Selected sheet units of the spacing modules and first and second flange modules are marked. In this particular example, each of the repeated planar grids 1002 comprises construction units that have a spacing module and both first and second flange modules. Thus, each construction unit is made up of a folding Miura-Ori mechanism of the type discussed above with reference to Figure 5 that has been split in two horizontally and connected together via the vertical sheet units of the spacing module. Repeating such units along Z effectively reforms a whole Miura-Ori mechanism

(comprising first flange units and second flange units from different planar grids 1002). This arrangement has high strength along Z in the deployed state because the spacing module sheet units in different vertical planes are aligned along Z.

In an alternative embodiment, a three dimensional grid is formed by repeating planar grids

1004,1006 that comprise construction units that each have a first flange module but not a second flange module. In this embodiment, only a single layer of flange module sheet units are thus provided in between each layer of spacing module sheet units. An example of this type of deployable structure 800 is illustrated in Figures 27-29. Figure 27 is a side view of the deployable structure 800. Figure 28 is a perspective view of the deployable structure 800 in a partially deployed sate. Figure 29 is a perspective view of the deployable structure 800 in the fully deployed state. Selected sheet units of the spacing modules and first flange modules are marked. In this embodiment, every other planar grid in the Z direction (e.g. the two planar grids marked 1004) have the same orientation and are aligned along Z with each other. However, the interleaved planar grids (e.g. planar grid 1006) are rotated by 180 degrees about Z relative to the planar grids 1004 on each side along Z. A consequence of this arrangement is that the vertical spacing module sheet units are displaced from each other along both the X and Y directions. In the fully deployed state of Figure 29, the displacement is equal to the width of the flange module sheet units, c. If such a deployable structure 800 were used in a load bearing application, the load path of a vertical force 1008 (see Figure 29) applied to the top planar grid would be offset, as shown by arrows 1010, resulting in a lower load-bearing capacity than if the load path followed a straight line (as in the embodiment of Figures 24-26).

The deployable structures 800 discussed above advantageously provide flat "flanges" (formed by the first and/or second flange modules) in the deployed state, above and below a structural "web" made up of the vertical sheet units of the spacing modules. This structure resembles a cold-rolled parallel flange channel found in steel structures and provides similar structural advantages.

Furthermore, the grid intersections consist of two layers of material joined together along the hinge, resulting in greater joint rigidity than the conventional method of forming a grid by cutting slits out of strips of cardboard and interlacing the strips.

In the prior art, as discussed above with reference to Figure 1, cardboard packaging partitions can be constructed using slotted sheets, but the resulting structure has to be constructed from separate units and/or is relatively weak. Figures 30 and 31 illustrate one way in which a deployable structure 800 according to an embodiment can be used to provide an improved solution. Figure 30 illustrates separated strips of spacing module sheet units and first flange module sheet units in the storage state. Figure 31 illustrates the same sheet units when connected together to form the deployable structure 800 (in the deployed state as shown). In the context of providing partitions, the structure would be used "upside down" (in comparison to the embodiments discussed above) with the first flange unit on the underside. In this way, the flattening of the flange unit on deployment will not impede the insertion of products (e.g. bottles) in the grid interstices of the structure 800. The absence of second flange modules reduces the structural restraint provided to the spacing module sheet units relative to arrangements that comprise both first and second flange modules, but in the context of packaging partitions this may not be a problem because the structure 800 is not expected to support any vertical loads. The structure 800 is still restrained by the first flange module to fold out to form the required orthogonal grid.

In the construction industry, storage space on site is limited and construction elements may need to be erected quickly. According to an embodiment a kit is provided that can be used for forming a partition element quickly and which can be stored compactly before use. The partition element may be used to form all or a part of a wall (e.g. a non-load-bearing wall), a floor or a ceiling for example. The kit comprises a deployable structure 800 according to an embodiment and, optionally, one or more outer sheet elements for attachment to the deployable structure 800 when in the deployed state. The deployable structure can be folded flat and the outer sheet elements are intrinsically flat. The kit can thus be stored and/or transported effectively. The deployable structure, as discussed above, can be deployed in a single operation without the need to connect multiple elements together. The partition element can thus be put together quickly and easily using the kit.

An example of such a kit is illustrated in Figure 32. Figure 32 is a schematic exploded view of the kit comprising a deployable structure 800 according to an embodiment and outer sheet units 1102 and 1104 (e.g. formed from oriented strand board or plasterboard). Figure 33 shows the partition element 1106 formed using the kit of Figure 32.

In the discussion above, the thickness of the sheet unit material was not considered explicitly.

However, for practical uses the likely materials of construction would be cardboard or wood of finite thickness, whilst aluminium or steel could also be used for other potential applications. The thickness of the sheet units therefore needs to be considered, since a non-negligible thickness has an effect on the

construction of joints.

According to an embodiment, cut-outs are formed in the sheet units to allow the sheet units to overlap with each other in the manner required to perform the folding discussed above (e.g. to allow sheet units to engage with each other in the region of overlap, for example with one or both embedded at least partially in the other, to allow allow the sheet units to fold into a state in which they are parallel with each other).

Mechanisms for implementing the hinges of the deployable structures 800 may involve attaching plates or other elements of finite thickness to the sheet units. Piano-type hinges, for example made of metal (e.g. steel or brass) could be used. In order to allow sheet units to overlap where such hinges are used, sections of the sheet units can be cut away to accommodate the hinge material that would otherwise protrude beyond the planes of the sheet units. Thus, the hinge material can be connected to the sheet units in such a way as to be flush with the surrounding sheet unit, for example.

In an embodiment, one or more of the sheets are integrally connected to each other with a hinge between such connected sheet units being implemented by reducing the rigidity of the sheet material along a line between the connected sheet units. In an embodiment, the reduction in rigidity is achieved by folding the sheet material along the line. Alternatively or additionally, the reduction in rigidity is achieved by reducing the thickness of the sheet material along the line.

In the embodiments discussed in detail above, the sheet units 301-304 of the spacing modules each comprise a single planar sheet. The sheet units 301-304 are thus vertically aligned in the deployed state (i.e. they have coplanar normals). Embodiments of this type tend to provide good rigidity against compressive forces in the vertical direction (perpendicular to the plane of the coplanar normals). However, it is not essential that the sheet units 301-304 be constructed from single planar sheets. In alternative embodiments, the sheet units 301-304 each comprise multiple sub-sheets that are hinged together. Each of the sub-sheets may be planar but they are connected together by hinges which allow the sub-sheets of a given sheet unit 301-304 to become non-parallel, at least in the deployed state. In an embodiment, the sub-sheets of each sheet unit 301-304 are hinged together about hinges (e.g. hinges 1204 in Figure 34) that are parallel to each other (where two or more are provided) and/or with one of the directions of compression of the flange units (e.g. the hinges are horizontal where the compression is provided in a vertical direction as shown in Figures 34 and 35 discussed below). Example arrangements are described below with reference to Figures 34 and 35.

Figure 34 is a side view of a deployable structure comprising two construction units, each comprising a spacing module having sheet units that are divided into two sub-sheets. The structure is in the storage state as shown with all of the sheet units and sub-sheets substantially coplanar with each other (neglecting sheet thicknesses). The structure is therefore substantially flat as shown. Dashed lines and dot- dashed lines show respectively where valley and mountain folds can be made about the hinges to switch from the storage state to the deployed state. Sub-sheets 301a and 301b make up a first sheet unit of the spacing module (corresponding to the sheet unit 301 of an embodiment such as that shown in Figure 15 for example). Sub-sheets 302a and 302b make up a second sheet of the spacing module (corresponding to the sheet unit 302 of an embodiment such as that shown in Figure 15 for example). Sub-sheets corresponding to the other two sheet units of the spacing module, as well as the sheet units of the first and second flange units other than the sheet units 305, 306, 309 and 310 shown, are hidden from view behind, but in this embodiment would simply be mirror images of the sub-sheets and sheet units shown.

In an embodiment, the sub-sheets are allowed to hinge relative to each other by being arranged such that adjacent sub-sheets in different sheet units are connected by hinges 1202 that are at an oblique angle 1200 to the hinge lines 1204 connecting sub-sheets in the same sheet unit to each other and/or to the flange modules above and/or below (with which the hinges 1202 intersect). Where the angle is near 90 degrees, the degree of hinging between sub-sheets of the same sheet unit will be small and the sub-sheets will be aligned near to the vertical in the deployed state. This arrangement will tend to provide relatively high resistance against compressive forces and a wider profile in the direction of compression. Where the angle 1200 is much smaller than 90 degrees (e.g. 60 degrees), the degree of hinging between sub-sheets of the same sheet unit will be much larger and the sub-sheets will be aligned further away from the vertical in the deployed state. This arrangement will tend to provide lower resistance against compressive forces and a narrower (more compressed) profile in the direction of compression.

Figure 35 is a side view of a deployable structure corresponding to that shown in Figure 34 except that each of the sheet units of the spacing module comprises three sub-sheets. Sub-sheets 301a, 301b and 301c make up a first sheet unit of the spacing module and sub-sheets 302a, 302b and 302c make up a second sheet of the spacing module. In other embodiments each of the sheet units of the spacing modules may comprise more than three sub-sheets.

Arranging for each of the sheet units of the spacing modules to comprise multiple sub-sheets as described above tends to provide a greater degree of springiness (less rigidity) in the direction of compression of the flange units in the deployed state. This property may be useful for example where the deployable structure needs to provide a progressive impact resistance or cushioning, for example. A deployable structure of this type may be used for packaging delicate articles, for example. Alternatively or additionally, a deployable structure of this type may be used as part of the construction of a vehicle, where low weight and cushioning in the event of impact are desirable.

In an embodiment, the geometry of the sub-sheets is such that in a deployed state in which all of the sheet units of the flange modules are flat against each other (coplanar), the sub-sheets of the spacing module are not coplanar. Thus, the spacing module still serves to provide a spacing function in the direction of compression (vertical in the orientation shown). In other words, in the deployed state the flange modules will be generally compressed by a greater proportion than the spacing modules in the vertical direction.

The extent to which the spacing modules having multiple sub-sheets are compressed in the direction of compression of the flange units is determined by the angle a defining the hinging and therefore compression of the flange units and the angle or angles (e.g. angle 1200) defining the hinging and therefore compression of the spacing modules, as well as the geometry of the sub-sheets and the number of sub-sheets provided in each spacing module sheet unit. By suitable selection of these parameters a wide variety of properties can be obtained. The deployable structure can therefore easily be tailored to operate effectively in a wide variety of situations even without changing the material properties of the sheet units and the way in which they are hinged together (which provides further scope for tailoring the properties of the structure as needed).

Unless stated otherwise, references to a compression direction of a flange module and/or spacing module means the vertical direction in the orientation shown in the figures. This is generally the direction of interest in relation to the spacing and compression resistance properties provided by the spacing modules. However, as noted, compression of the flange modules and spacing modules can occur also in a horizontal direction lying within the plane of the sheet units when in the storage state, in the sense that this dimension of the flange modules and spacing modules will also tend to decrease during deployment.

Claims

1. A employable structure, comprising:

a first construction unit comprising a spacing module and a first flange module, wherein:

the spacing module comprises first, second, third and fourth sheet units that are hinged together; the first flange module comprises fifth, sixth, seventh and eighth sheet units that are hinged together; and

the spacing module and first flange module are connected together by hinges in such a way as to be switchable by rotation about the hinges between:

a storage state in which the first to eighth sheet units are substantially coplanar; and

a deployed state in which the first flange module is compressed in two orthogonal directions relative to the storage state.

2. A structure according to claim 1, wherein the first to fourth sheet units are each planar in the deployed state.

3. A structure according to claim 2, wherein the first to fourth sheets lie in planes having coplanar normals, at least two of the planes being non-parallel.

4. A structure according to claim 3, wherein one of the two orthogonal directions of compression is perpendicular to the plane of the coplanar normals.

5. A structure according to claim 1, wherein the first to fourth sheet units each comprise two or more planar sub-sheets that are hinged together.

6. A structure according to claim 5, wherein the sub-sheets are hinged together along lines that are perpendicular to one of the two orthogonal directions of compression, rotation about these hinges during deployment causing the first to fourth sheet units to be compressed in a direction parallel to the one of the two orthogonal directions, thereby compressing the spacing module in that direction.

7. A structure according to claim 6, wherein the compression of the spacing module along the one of the two orthogonal directions of compression in the deployed state relative to the size of the spacing module along that direction in the storage state is less than the compression of the first flange module along the one of the two orthogonal directions of compression in the deployed state relative to the size of the first flange module along that direction in the storage state.

8. A structure according to claim 6 or 7, wherein, in the deployed state, the first flange module is substantially flat, the sheet units of the first flange module being substantially parallel to each other, and the sub-sheets of each of the first to fourth sheet units are not parallel to each other.

9. A structure according to any of the preceding claims, wherein the hinges and sheet units of the spacing module and the first flange module are configured such that the mechanism for switching between the storage state and the deployed state has a single degree of freedom only.

10. A structure according to any of the preceding claims, wherein the hinges connecting together the sheet units of the first flange module have parallel axes of operation.

11. A structure according to any of the preceding claims, wherein:

the first construction unit further comprises a second flange module, the second flange module having the same construction as the first flange module and being connected to the spacing module by hinges on an opposite side to the first flange module, wherein:

in the storage state the sheet units of the second flange module are substantially coplanar with the sheet units of the spacing module and first flange module; and

in the deployed state, the second flange module is compressed in two orthogonal directions relative to the storage state.

12. A structure according to claim 11, wherein the hinges connecting together the sheet units of the second flange module have parallel axes of operation.

13. A structure according to any of the preceding claims, wherein:

the first flange module and/or, if provided, the second flange module is/are substantially flat in the deployed state, the sheet units of flange module(s) lying substantially parallel to each other and to the plane of the coplanar normals.

14. A structure according to any of the preceding claims, further comprising:

one or more further construction units each of the same configuration as the first construction unit and connected to the first construction unit by hinges, wherein all of the spacing modules and flange modules of the further construction units are switchable in unison with each other and with the first construction unit by rotation about the hinges of the construction units between the storage state and the deployed state of each construction unit.

15. A structure according to claim 14, wherein the further construction units comprise a set of one or more in-plane construction units that when connected together form a linear arrangement of construction units extending along a line parallel to the plane of the coplanar normals of the first to fourth sheets units.

16. A structure according to claim 15, wherein:

the first sheet unit is connected along a hinge to the second sheet unit, the second sheet unit is connected along a hinge to the third sheet unit, and the third sheet unit is connected along a hinge to the fourth sheet unit; and either:

said line intersects the hinge connecting the first sheet unit to the fourth sheet unit and the hinge connecting the second sheet unit to the third sheet unit, with adjacent construction units being connected together at these two hinges; or

said line intersects the hinge connecting the first sheet unit to the second sheet unit and the hinge connecting the third sheet unit to the fourth sheet unit, with adjacent construction units being connected together at these hinges.

17. A structure according to claim 15 or 16, wherein the set of in-plane construction units comprises a plurality of the linear arrangements connected together in parallel to form a planar grid in the deployed state.

18. A structure according to claim 17, wherein the further construction units comprise a plurality of said planar grids stacked on top of each other in a direction perpendicular to the plane of the planar grids to form a three-dimensional grid.

19. A structure according to claim 18, wherein at least two of the planar grids comprise construction units having both first and second flange modules.

20. A structure according to claim 19, wherein adjacent planar grids having both first and second flange modules that are mirror images of each other about a plane parallel to the planes of the planar grids.

21. A structure according to any of claims 18-20, wherein at least two of the planar grids comprise construction units having first flange modules only.

22. A structure according to claim 21, wherein adjacent planar grids having first flange modules only are rotated relative to each other by 180 degrees about an axis perpendicular to the plane of the planar grids.

23. A structure according to any of the preceding claims, wherein:

the first sheet unit is connected along a first hinge to the second sheet unit, the second sheet unit is connected along a second hinge to the third sheet unit, the third sheet unit is connected along a third hinge to the fourth sheet unit, and the fourth sheet unit is connected along a fourth hinge to the first sheet unit; and the first, second, third and fourth hinges have parallel axes of operation.

24. A structure according to claim 23, wherein:

the fifth sheet unit is connected along a fifth hinge to the sixth sheet unit, the sixth sheet unit is connected along a sixth hinge to the seventh sheet unit, the seventh sheet unit is connected along a seventh hinge to the eight sheet unit, and the eighth sheet unit is connected along an eighth hinge to the fifth sheet unit; and

the fifth, sixth, seventh and eighth hinges have parallel axes of operation.

25. A structure according to claim 24, wherein:

the fifth sheet unit is connected along a ninth hinge to the first sheet unit, the sixth sheet unit is connected along a tenth hinge to the second sheet unit, the seventh sheet unit is connected along an eleventh hinge to the third sheet unit, and the eighth sheet unit is connected along a twelfth hinge to the fourth sheet unit;

the axes of operation of the ninth, tenth, eleventh and twelfth hinges are perpendicular to the axes of operation of the first, second, third and fourth hinges throughout the range of movement between the storage state to the deployed state; and

the axes of operation of the fifth, sixth, seventh and eighth hinges are at an oblique angle relative to the axes of operation of the first, second, third and fourth hinges in the storage state.

26. A structure according to claim 25, wherein one or more of the following conditions are satisfied: the axes of operation of the first, fifth, ninth and tenth hinges intersect at a first point;

the axes of operation of the second, sixth, tenth and eleventh hinges intersect at a second point; the axes of operation of the third, seventh, eleventh and twelfth hinges intersect at a third point; the axes of operation of the fourth, eighth, ninth and twelfth hinges interest at a fourth point.

27. A structure according to claim 25 or 26, wherein the oblique angle is 45 degrees.

28. A structure according to any of the preceding claims, wherein the sheet units of the spacing module are square or rectangular.

29. A structure according to any of the preceding claims, wherein the sheet units of the first flange module and/or, where provided, the second flange module, are parallelograms with non-orthogonal sides.

30. A structure according to any of the preceding claims, wherein where two different sheet units overlap with each other in the deployed state or storage state, one or both of the sheet units comprises cut-outs to allow the two sheet units to engage with each other during the overlap to allow the two sheets to be parallel to each other.

31. A structure according to any of the preceding claims, wherein one or more of the sheets are integrally connected to each other with a hinge between such connected sheets being implemented by reducing the rigidity of the sheet material along a line between the connected sheets.

32. A structure according to claim 31, wherein the reduction in rigidity is achieved by folding the sheet material along the line.

33. A structure according to claim 31 or 32, wherein the reduction in rigidity is achieved by reducing the thickness of the sheet material along the line.

34. A packaging material comprising a deployable structure according to any of the preceding claims.

35. A packaging material according to claim 34, wherein the deployable structure comprises a planar grid for providing partitioning between items to be packaged.

36. A kit for forming a partition element, the kit comprising a deployable structure according to any of the preceding claims.

37. A kit according to claim 36, further comprising one or more outer sheet elements for mounting on one or more outer surfaces of the deployable structure in the deployed state to form the partition element.

38. A deployable structure, packaging material, or kit arranged and/or configured to operate substantially as hereinbefore described with reference to and/or as illustrated in Figures 2-35.