GB2534197A

GB2534197A - Protective wall

Info

Publication number: GB2534197A
Application number: GB1500747.9A
Authority: GB
Inventors: George Down Kevin
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-01-16
Filing date: 2015-01-16
Publication date: 2016-07-20
Anticipated expiration: 2035-01-16
Also published as: GB2534197B; GB201500747D0

Abstract

A protective wall comprising two surfaces 3, 5 spaced from and parallel to each other, and an intermediate region 7 between them comprising substantially solid matter in the form of loose granular material 9 of a density less than 2000 kg per cubic metre and interstitial voids 11 such that the average density is less than 1400 kg per cubic metre. The granular material preferably has a density less than 1420 kg per cubic metre and the intermediate region may have an average density less than 1000 kg per cubic metre. The granular material may have a fracture toughness less than 1.6 MPa/m1/2, a melting point above 150 degrees centigrade and be one of polyoxymethylene, poly(methyl methacrylate), polystyrene, high-impact polystyrene, or a combination thereof. The two surfaces may comprise at least one layer of fibre-reinforced plastic material having a thickness of 3.5mm. The intermediate region may have a thickness of 60mm. Also provided is a shelter and method of constructing a shelter by coupling a plurality of the claimed protective walls to one another.

Description

PROTECTIVE WALL

The present invention relates generally to protective walls, in particular although not exclusively to light-weight blast walls, ballistics walls, defensive walls and shelters, and to a method of constructing a shelter.

Protective walls are used to protect buildings and/or people from explosions and/or ballistics, for instance due to terrorism or in a military environment. Typically, such walls are designed to protect against shockwaves and overpressure from nearby explosions, to protect against low-velocity projectiles including case fragments from high explosive weaponry such as artillery shells, bombs, IEDs, grenades and land mines, and to protect against high-velocity projectiles such as ballistics, ammunition and armour-piercing rounds.

Known forms of protection include containers holding sand or soil, for instance sand bags, wire mesh containers with heavy duty fabric liners, etc. These are light, compact and portable before deployment; however, they take a relatively long time to deploy and once in position are difficult to reposition. Such systems are effective against 'standard' ammunition, but tend to be less effective against armour piercing ammunition, as the sand/soil acts to stabilize the projectile as it enters the harrier, and ensuring that its momentum is carried forward. Thus, a significant depth of sand/soil is required to stop all forms of ammunition.

Another form of protection involves using concrete (or reinforced concrete) or steel sheeting. These forms of protection are also relatively heavy, requiring specialist machinery to deploy, and rely on direct deceleration of incoming projectiles; however, such projectiles can cause damage to the barrier resulting in subsequent projectiles being able to penetrate deeper into the barrier. In addition, ricochets are possible and may be hazardous to individuals and/or equipment nearby.

It is known that deceleration of projectiles is most effective by overturning (i.e. causing the projectile to tumble) or fragmentation (i.e. causing the projectile to break apart), and this is most apparent with armour-piercing ammunition.

It is therefore desirable to require overturn of a projectile on a minimal penetration depth, while at the same time preventing subsequent projectiles from using the same entry hole.

It has been suggested that providing a flat penetration surface, behind which are located movable ceramic granules, achieves this goal, by ensuring that incoming projectiles that penetrate the metal surface arc slowed by the destruction (i.c. crushing) or relatively brittle ceramic granules, which are then replaced by a fluid-like flow of similar granules into the path behind the projectile.

However, it is noted that ceramic granules are relatively heavy (having a density typically greater than twice that of water) and so deployment of these systems is also difficult and inconvenient.

According to a first aspect of the present invention, there is provided a protective wall, comprising: a first surface; a second surface spaced from the first surface and arranged substantially parallel to the first surface; and an intermediate region between the first and second surfaces, the intermediate region comprising substantially solid matter in the form of loose granular material having a density less than 2000 kg per cubic meter, and interstitial voids such that the average density of the region is less than 1400 kg per cubic meter. The solid matter may have a density less than 1600 kg per cubic meter, in particular less than 1500 kg per cubic meter, more particularly less than 1420 kg per cubic meter.

The solid material may be brittle. That is: the solid matter may break without significant deformation (strain), when subjected to stress; the solid matter may absorb relatively little energy prior to fracture; and/or the solid matter may fail when there is little or no evidence of plastic deformation before failure. 'the solid material may have a fracture toughness less than 5 MPa per Nm (i.e. MPa per square-root meter, 1.11)21/m"(0.5) or Alfa/m(1/2)), in particular less than 3, 2, 1.7, 1.6 1\412a/m(1/2).

In this way, the solid material will not deform upon impact of a projectile, but rather may break and he re-distributed throughout the interstitial voids/spaces.

The solid material may have a melting point above 140 degrees centigrade, in particular above 150 degrees centigrade, more particularly above 160 degrees centigrade, for instance above 170, 175, 200, 230 or 240 degrees centigrade.

In this way, the solid material will not melt upon impact of a ballistic projectile therewith. If material of a lower melting point were used, then the material would not break without significant deformation, but rather would deform and coalesce with adjacent granules. this would result in a solid, elastic and/or fluid mass which would stabilize the projectile, thereby increasing its effective stopping distance.

The solid matter may he a plastics material (e.g. a thermoplastics material), for instance Polyoxymethylene, Poly(methyl methacrylate), polystyrene and/or high-impact polystyrene or a combination thereof.

The voids may be filled with air or another gas and/or fluid. In preferred embodiments, the voids arc filled with a non-viscous fluid.

The average density of the region may be less than for instance 1300, 1120, 1000, 900, 700, 650, 525 or 260 kg per cubic meter. The region may have a density less than 70% or 65% of the density of the solid matter. For instance, the granules may be substantially spherical in shape (however, other shapes such as oblate/prolate spheroids are considered), and may be randomly distributed within the region.

The granules may have a circumference of between approximately 5mm and 25mm, in particular between approximately 7.5mm and 20mm, more particularly between approximately 10m and 15rnm, for example approximately 12mm. Alternatively, the granules may have a diameter of between approximately 5rnm and 25mm, in particular between approximately 7.5mm and 20rnm, more particularly between approximately 1 Om and 15mm, for example approximately 12mm.

In one embodiment in which spherical granules of Polyoxymethylene are used, a weight saving of 80% may be achieved over use of ceramic/mineral granules.

The protective wall may comprise a panel having a width and/or height of at least 0.5m.

The first and/or second surface may be substantially flat; however, other shapes are considered. For instance, the surface may be curved to form the external profile of a building, and/or as 21 corner piece for added strength. Alternatively or additionally, the surface may he corrugated, such that impinging projectiles are deflected from their trajectory, thereby leading to tumbling and reduction in penetration distance. Similarly, the surface may comprise a plurality of overlapping sub-surfaces, dimples and/or dents, for a similar purpose.

The first and/or second surface may comprise at least one layer of fibre-reinforced plastic material. For instance, the first and/or second surface may comprise only one layer of fibre-reinforced plastic material, or may comprise a plurality of layers of fibre-reinforced plastic material, for instance at least (or approximately) 2, 3, 4, 5, 6, 7, 8, 9 or 10 layers.

The first and/or second surfaces may comprise layer(s) of chop strand matting or woven and/or polymer based fibre composites (for instance exhibiting high inter-laminar breaking stress), for instance polybenzobisoxazole and/or polythene fibre, and/or glass and/or aramide fibre. The first and/or second surfaces may further comprise trans-laminar reinforcement.

Alternatively or additionally, the first and/or second surface may comprise wood (e.g. timber, plywood, medium density fibreboard, particle board and/or chipboard), sheet and/or corrugated metal (e.g. steel), sheet plastics material, any other suitable sheet material or a combination thereof.

The first surface and/or the second surface may be at least (or approximately) 1mm, 2mm, 3mm, 3.5mm, 4mm, 5mm, 6mm, 7mm and/or 8mm in thickness, or may he up to (or approximately) 15mm, 20mm, 30mm, 35n-nn or 40rnm in thickness.

The intermediate region may have a thickness of at least (or approximately) 50mm, 100mm, 150mm, 200mm or 250mm.

According to a second aspect of the present invention, there is provided a protective wall, comprising: a first surface comprising at least one layer of fibre-reinforced plastic material; a second surface spaced from the first surface and arranged substantially parallel to the first surface, the second surface comprising at least one further layer of fibre-reinforced plastic material; and an intermediate region between the first and second surfaces, the intermediate region having a thickness of at least 18mm, and comprising substantially solid matter having a density less than 2000 kg per cubic meter.

In this way, a protective wall is provided that is a light-weight alternative to those known in the art. In particular, the first surface acts to slow case fragments from high explosive weaponry such as artillery shells, bombs, IEDs, grenades and land mines, and other low-velocity projectiles such as shotgun shot. The intermediate region between the first and second surfaces may act to further slow any projectiles that pass through the first surface, but may also act to provide support and/or rigidity to the protective wall. The second surface may act to slow any projectiles that pass through both the first surface and the intermediate region.

In particular, it is noted that fibre-reinforced plastic material (of a substantially reduced thickness from that in the present invention) is used in body armour for protecting individuals from such low-velocity projectiles; however, use in protective walls has been avoided due to the additional requirements of needing to withstand shockwaves and overpressure from explosions, and to withstand high-velocity projectiles. In many environments, protection from high-velocity projectiles is unnecessary, and so the light-weight system of the present invention may be used without compromising safety. In addition, the inventor has identified that to withstand shockwaves and overpressure, heavy weight and intrinsic inertia of the protective wall is unnecessary; rather, it is sufficient for a light-weight protective wall to be held by a support structure, for instance other protective walls arranged in a self-supporting arrangement, or by affixing to a building. Use of metal and concrete is therefore not

required, despite its prevalence in the field.

In some embodiments, the solid matter may have a density less than 1000 kg per cubic meter, in particular less than 750 kg per cubic meter, more particularly less than 700 or 400 kg per cubic meter. The solid matter may he, for instance, wood (e.g. timber, plywood, medium density fibreboard, particle board and/or chipboard).

The solid matter may be loose granular material as in the first aspect, and may have features in common with the first aspect.

The first and/or second surface may comprise only one layer of fibre-reinforced plastic material, or may comprise a plurality of layers of fibre-0:inbreed plastic material, for instance at least (or approximately) 2, 3, 4, 5, 6, 7, 8, 9 or 10 layers.

The first surface and/or the second surface may he at least (or approximately) 1mm, 2mm, 3mm, 3.5mm, 4mm, 5mm, 6mm, 7mm and/or 8mm in thickness.

Tests show that such a thickness of fibre-reinforced plastic material is sufficient to pass current blast and ballistics tests, such as the British Standards Institution (BST Group) standards BS EN 1522:1999 and BS EN 1523:1999.

The intermediate region may have a thickness of at least (or approximately) 18mm, 27nun, 36mm, 45mm or 54mm.

According to a third aspect of the present invention, there is provided a shelter comprising a plurality of protective walls according to the first or second aspect, wherein each protective wall is coupled to a neighbouring protective wall to form a shelter.

The shelter may comprise a roof. The shelter may enclose an interior space. The shelter may be free-standing. Each wall of the shelter may support at least one further wall of the shelter. The description "shelter" does not necessarily mean that its intended purpose or suitability is for the sheltering of persons therein, but rather it describes a region inside that is sheltered from an explosive and/or ballistic event. The term 'protective kiosk' may be used interchangeably.

According to a fourth aspect of the present invention, there is provided a method of constructing a shelter, the method comprising providing a plurality of protective walls according to the first or second aspect, and coupling each protective wall to at least one neighbouring protective wall to form a shelter according to the third aspect.

The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. '111e reference figures quoted below refer to the attached drawings.

Figure 1 is a cross section through a protective wall according to the present invention.

Figure 2 is a perspective view of a shelter according to the present invention. The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. Tn the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. it is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

Tt is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. Tt means that with respect to the present invention, the only relevant components of the device are A and B. Reference throughout this specification to "an embodiment" or "an aspect" means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases "in one embodiment", "in an embodiment", or "in an aspect" in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would he apparent to one of ordinary skill in the art from this

disclosure, in one or more embodiments or aspects.

Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspect. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth.

However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Tn the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

The use of the term "at least one" may mean only one in certain circumstances. The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features of the invention. It is clear that other arrangements can he configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching of the invention, the invention being limited only by the terms of the appended claims.

Figure 1 is a cross section through a section of a protective wall 1 having a first surface 3 comprising a plurality of layers of fibre-reinforced plastic material laminated on plywood, a second surface 5 spaced from (and parallel to) the first surface 3 and substantially similar in form thereto, and an intermediate region 7 comprising a plurality of spherical balls 9 of polyoxymethylene in a substantially random configuration.

Spaces 11 between the balls 9 are left empty, and are filled with air. In some embodiments, a polymer spray is applied to an exterior surface of the wall 1.

Figure 2 is a perspective view of a shelter 13 incorporating four substantially vertical protective walls 1 illustrated in figure 1 to enclose a space therein. The shelter 13 also comprises a roof 15 that is in this embodiment also formed of a protective wall 1. In alternative embodiments (not shown) the roof is provided secured to the side walls 1 in a similar manner, such that there is no external flange or overhang. A security door 17 is provided in one of the walls 1 on hinges 19 and lockable via a lock 21. In alternative embodiments, the security door 17 may be hinged on the inside to prevent damage occurring to the hinges 19, and the lock 21 may be a low-profile lock fitted flush with the surface of the door 17 to minimise damage thereto. Security vent grills 23 are also provided to allow ventilation into the enclosure; however, in alternative embodiments the grills may he absent in cases where no ventilation is necessary, or where alternative ventilation is provided, such as with an air conditioning unit or T TVAC system. The walls 1 and roof 15 are coupled together by fixings 25, while the walls are additionally coupled to a concrete foundation 27 by fixings 29 using an external flange; however, an internal flange may be used as an alternative. Any suitable form of fixings may be used such as anchor bolts and/or expansion bolts. In sonic CtilbOdlifICHtti an internal floor is provided as part of the shelter/kiosk.

Claims

CLAIMS1. A protective wall, comprising: a first surface; a second surface spaced from the first surface and arranged substantially parallel to the first surface; and an intermediate region between the first and second surfaces, the intermediate region comprising substantially solid matter in the form of loose granular material having a density less than 2000 kg per cubic meter, and interstitial voids such that the average density of the region is less than 1400 kg per cubic meter.
2. The protective wall of claim 1, in which the granular material has a density less than 1420 kg per cubic meter, and the average density of the region is less than 1000 kg per cubic meter.
3. The protective wall of claim 1 or claim 2, in which the granular material has a fracture toughness less than 1.6M0a/m2).
4. The protective wall of any preceding claim, in which the granular material has a melting point above 150 degrees centigrade.
5. A protective wall according to any preceding claim, in which the granular material is selected from the group containing polyoxymethylene, poly(methyl methacrylate), polystyrene, high-impact polystyrene, or a combination thereof.
6. A protective wall according to any preceding claim, in which at least one of the first and second surfaces comprises at least one layer of fibre-reinforced plastic material having a thickness of at least 3.5mm.
7. A protective wall according to any preceding claim, which the intermediate region has a thickness of approximately 60mm.
8. A protective wall, comprising: a first surface comprising at least one layer of fibre-reinforced plastic material; a second surface spaced from the first surface and arranged substantially parallel to the first surface, the second surface comprising at least one further layer of fibre-reinforced plastic material; and an intermediate region between the first and second surfaces, the intermediate region having a thickness of at least 27mm, and comprising substantially solid matter having a density less than 2000 kg per cubic meter.
9. A shelter comprising a plurality of protective walls according to any preceding claim, wherein each protective wall is coupled to a neighbouring protective wall to form a shelter.10. A method of constructing a shelter, the method comprising providing a plurality of protective walls according to any one of claims 1 to 8, and coupling each protective wall to at least one neighbouring protective wall to form a shelter.
10. A protective wall substantially as hereinbefore described with reference to figure 1.
11. A shelter substantially as hereinbefore described with reference to figure 2.