WO2017158352A1

WO2017158352A1 - Blast and pressure wave resistant structure

Info

Publication number: WO2017158352A1
Application number: PCT/GB2017/050706
Authority: WO
Inventors: Simone J DE-GALE; Thomas R Shelley
Original assignee: Blast Absorption Systems Limited
Priority date: 2016-03-15
Filing date: 2017-03-15
Publication date: 2017-09-21
Also published as: GB201604388D0; GB2560485A; GB2560485B

Abstract

A system and method for enhancing the stored elastic strain energy of a structure to increase its capability to withstand external blast, pressure waves and/or projectiles. A curved pre-stress is applied to a material to increase tensile forces on one side of the material and compressive forces on the other side of the material.

Description

Blast and pressure wave resistant structure

Field of the Invention

The present invention relates generally to a blast and pressure resistant structure comprising curved pre-stressed elements, which is the interoperability of tensile and compressive forces, to enhance the stored elastic strain energy of a structure. The structures may be employed in military, maritime, oil and gas and civilian infrastructure environments.

Description of Related Art

The idea of "linear pre-stressed concrete" is well known in industry as a method of enhancing the load bearing capability of a concrete structure such as a roof, bridge, or tunnel. US2102963 (Miller) discloses a method for manufacturing armour plates comprising the use of bimetallic plates that are carburized. The hard (outer) side is required to be in compression and the softer (inner) side is placed under tension. US2359446 (Scudder) -discloses a method of constructing multi-layer pressure vessels and the pre-stressing of the cylindrical walls of the vessel during fabrication. The pressure vessels are intended to contain high internal pressures. US2382139 (Clement) discloses a pre-stressed reinforced concrete and pre-stressed composite structure wherein steel and concrete members or timber and concrete members are combined into one static unit, designed to carry a predetermined load.

US302349S (Noland) discloses a method of cold-working a hollow chamber composed or a metal material, which comprises affixing glass to the metal and stressing the structure beyond the yield strength of the metal material with the glass being of sufficient thickness to carry a major portion of the load added without rupture.

US3474651 (Hicks et al) discloses apparatus for expanding a continuous corrosion resistant liner into intimate contact with the inside of a large vessel or tank.

US4965973 (Engebretsen) discloses a device for load carrying structures comprising a pre-stressed reinforced beam of laminated wood, the wood having a curved convex tension side and a curved concave compression side in its unloaded condition.

US5042751 (Kolom) discloses a pressure vessel having a non-circular axial cross-section and a method for its construction.

CH679244 (Bauer AG) discloses armoured cladding for a vehicle, safe or strong room comprising several parallel layers and different materials.

WO2006037314 (Farmingtons Holding GMBH) discloses a device for protection from mines and explosives for vehicles, comprising a shield mounted under the vehicle and located at a distance from the vehicle floor.

US2009224102 (White) discloses a structure protected from premature buckling for resisting multiple bending forces. The structure is a compound curved, relatively thin sheet of metal or a composite having a cambered shape mat is initially arched. WO2011039065 (De Gale et al) discloses the use of one or more pre-stressed curved members, to enhance the strength of any curved structure.

US2015/268007 (Bergman et al) discloses a light weight pre-stressed antiballistic article including a monolith ceramic plate/tile bonded to a thin lightweight thermal expansion material with an adhesive, characterized, in that the thermal expansion material has a thermal expansion coefficient at least 50% higher than the ceramic plate tile, and the thermal expansion material is bonded to either the front face, back face or bom faces of the ceramic plate tile at a bonding temperature of between 50° C. and 250° C. with adhesive and subsequently cooled, whereby upon cooling, the bonded thermal expansion material contracts to a greater extent than the ceramic plate tile, exerting compression stress on the ceramic plate/tile.

Summary of invention

The present invention is directed to a blast and pressure wave resistant structure comprising a first member and a second member, wherein the first member is a yieldably resilient panel that is deformed to create a curved portion therein, wherein the deformed panel has a convex surface and a concave surface, wherein the panel is retained in that deformed state and wherein the second member is bonded to the first member to create a protective layer therefor.

The deformation of the first member may include deformation by the use of mechanical forces, for example forcing the ends and/or middle section in a particular direction, or the use of fluids at different temperatures to cause deformation. Once the deformation has occurred and the first member is in a stressed state, it may be retained in that stressed condition by mechanically restraining it from elastically returning to its original state. This mechanical restraint may be in the form of an unstressed framework to which the first member is attached or it may be another unstressed element that can retain the first member in that position. Any mechanical restraint is sufficiently strong to overcome the stresses in the first member and so resist the first member deforming the mechanical restraint. Where a framework is used, this may be in the form of a surrounding metallic or composite framework, or, as an alternatively, where the first member is attached to a structure, for example, a vehicle, the attachment members, which may be brackets, rivets, screws or similar, may be sufficiently strong to retain the deformed member in that pre- stressed state.

The structure can be made from either just one material or a plurality of materials to form the said characteristics. The first member may be, for example, a metal panel, or it may be a composite structure, for example fibres retained in resin.

The present invention further relates to the application of a curved pre-stress structure to increase the resistance to blast and pressure waves by means of enhancing the stored elastic strain energy of a material to comprise a structure that will be more resistant to external blast, pressure waves and/or projectiles than that which otherwise would be the case.

Just as pre-stressed concrete enables the structure to carry a heavier load, so a carefully designed material that is pre-stressed through curvature enables greater elasticity and absorptive capacity in order to withstand the impact of external blast and pressure waves. This may be particularly advantageous for the purpose of: defensive protection against such blasts and pressure waves as may be expected in the military environment, for example for vehicle protection or body armour; marine environments, for example, external water impact on the bow of a racing hull of a boat; oil and gas environments, for example, exposure to external blast and pressure waves for protecting pipelines; and general infrastructure and industrial environments, for example against rail tunnel boom from high speed trains entering and exiting a tunnel. In addition, the present invention may induce the necessary pre-stress in relevant materials and combinations of materials, especially in alloys and advanced fibre reinforced plastic (FRP) composites, mat are viewed as particularly relevant to particular applications, as detailed herein. This present invention differs from the concept of a bent or curved structure having increased load-bearing capacity. A bent or curved structure is manufactured in a bent or curve-like manner where the tensile and compressive forces are balanced. However, the present invention increases the natural stresses within the material to create a highly complementary imbalance of stresses, which in turn, lower the maximum deflection and increase the blast absorption capabilities of that material and structure, which repeatedly through testing have found an improvement of performance for the said material when subjected to blast and pressure waves. The present invention is particularly effective when pressure is exerted onto the tensile side of the structure. Where the tensile surface of the structure is present to the on-coming wave or projectile, the resistance is increased compared to the other surface.

Preferably, at least the first member is held around at least part of its perimeter within an unstressed frame and the unstressed frame retains the deformed first member in that deformed state. The use of an unstressed frame allows the first, pre-stressed member to be retained in position.

Advantageously, a material is sandwiched between the first and second members. This provides the opportunity to provide further characteristics to the structure, where required. The intermediate material, or materials where a plurality are present, may provide further mechanisms for wave absorption or the absorption of energy from a projectile. Furthermore, the structure may be provided with an intermediate layer to absorb sound waves, thereby providing sound insulation in addition to the resistance to pressure waves and or projectiles. Heat insulation may also be applied.

In one arrangement, the first and/or second member comprises at least one material selected from a group comprising: composite material; metallic material; plastics material; ceramic material; concrete; and polymer resin. This list is intended to be indicative and not limiting.

In a preferred embodiment, the second member is unstressed. The application of an unstressed material assists with keeping the first member stressed and provides a protective layer to the stressed layer. Employing an unstressed member assists with retaining the first pre-stressed member in place and in its deformed state.

Preferably, the blast and pressure wave resistant structure is incorporated into and/or applied to the item and the item is selected from a group comprising: a land vehicle; personal protection equipment; a building; a tunnel structure; an oil rig; a maritime vessel; a submarine; armour plating and a remotely operated underwater vehicle. The present invention is intended to provide resistance to an external blast and pressure waves, thus providing an element of protection to those behind the internal surface of the structure. Where the structure is attached, or applied, to an item, the convex surface of the first member is directed outwardly from the item and the concave surface is directed inwardly towards the item. This presents the stressed convex layer to any blast and/or pressure waves. The present invention extends to a method of making a blast and pressure wave resistant structure as described herein, wherein the method comprises the steps of:

providing a first member in the form of a panel of material;

heating at least one portion of the panel of material;

providing a force to one or more locations on the panel of material;

providing a cooling fluid to one side of the panel of material to induce compressive forces of that one side of the panel and tensile forces of the other side of the panel, thereby deforming the panel of material such that a convex and concave side are formed therein; and

attaching a second member to the first member.

By employing a mechanical force to at least one location of the panel of material and applying a cooling fluid to one side, the panel is readily deformed into a stressed state. It can then be held in that state by way of the second member and/or a frame to retain the panel with unbalanced forces, thus, creating a structure that is more readily able to withstand blast and pressure waves and proj ectiles.

Preferably heating of the panel continues whilst the cooling fluid is applied. The heating of the panel in combination with the cooling may further enhance the stressing of the panel.

Advantageously, the force is provided to one or more edges of the panel of material.

In one arrangement, once the panel of material is deformed, is connected to an unstressed framework about at least part of the perimeter of the panel of material. This provides a secondary structure that assists with maintaining the deformed panel of material in a stressed manner.

In the present invention, may be in the form of a system and/or method for enhancing the stored elastic strain energy of a structure to increase its capability to withstand external blast, pressure waves and/or projectiles. The invention involves a curved pre- stress force applied to enhance the stored elastic strain energy of a structure to increase its capability to withstand external blast and pressure waves. A curved pre-stress is applied to a material to increase tensile forces on one side of the material and compressive forces on the other side of the material. In doing so, the structure is more resistant to forces exerted onto the tensile side of the structure. Once applied, an external force in the form of a blast and/or pressure wave would have to invert the tensile force into compression and in addition, convert the compressive force into tension before the collapse process starts. The curved pre-stress is retained by the processes required to manufacture the structure. The structure may be incorporated into a system to protect a vulnerable part of a vehicular or building structure.

In the present invention, there is provided a compressive force on the innermost side of the structure and tension on its outermost side to absorb blast and pressure waves from its outermost side, mat is, waves approaching the outermost, convex side.

The present invention involves pre-stressing the structure, both on its tensile side or compressive side, to be pre-stressed up to, but not beyond, the maximum yield point of strength to increase the elasticity of the chosen material for the patent applied characteristics.

Whilst some previously proposed structures focus upon equalising the operating pressure stress distribution on the inside and outside of a vessel, the present invention relates to resisting the impact of an external blast or pressure wave.

When employed on a vehicle, the structure of the pre-stressed armour plate aids with the absorption the blast and pressure waves. Brief Description of the Drawings

Embodiments of the present invention will now be described in relation to the accompanying figures, in which:

Figure 1 illustrates the manufacturing process of the curved pre-stress panels in accordance with the present invention

Figure 2 illustrates a schematic diagram of an exemplary architecture of integrated armour for the underbody of armoured land vehicles in accordance with the present invention;

Figure 3 illustrates a schematic diagram of an alternative exemplary architecture of integrated armour for the underbody of armoured land vehicles in accordance with the present invention;

Figure 4 illustrates a schematic diagram of an exemplary architecture for retrofitted metal or alloy armour for the underbody of armoured land vehicles in accordance with the present invention;

Figure 5 illustrates a schematic diagram of an exemplary architecture for retrofitted advanced composite armour for the underbody of armoured land vehicles in accordance with the present invention;

Figure 6 illustrates a schematic diagram of an exemplary architecture of armour affixed to the side of a vehicle to protect against projectiles in accordance with the present invention;

Figure 7 illustrates a domed construction used for a variety of applications on a micro and macro scale incorporating the curved pre-stress processes in accordance with the present invention;

Figure 8 illustrates a schematic diagram of an exemplary architecture of a Building shelter in accordance with the present invention;

Figure 9 illustrates a schematic diagram of an exemplary architecture for a Protection Shield in accordance with the present invention;

Figure 10 illustrates schematic diagram of exemplary architecture for Personal Protection Shield in accordance with the present invention;

Figure 11 illustrates a schematic diagram of exemplary architecture for Body Protection Armour in accordance with the present invention; Figure 12 illustrates a schematic diagram of an exemplary architecture for enhancing the strength of the Sub-Structure of a Maritime Vessel in accordance with the present invention;

Figure 13 illustrates a schematic diagram of an exemplary architecture for increasing the stiffness the hull of a Maritime Vessel in accordance with the present invention;

Figure 14 illustrates a schematic diagram of an exemplary architecture for reducing the weight of the Super-Structure of a Maritime Vessel in accordance with the present invention;

Figure 15 illustrates a schematic diagram of an exemplary architecture for mitigating the effects of tunnel boom in accordance with the present invention;

Figure 16 illustrates a schematic diagram of an exemplary architecture for reinforcing a tunnel in accordance with the present invention;

Figure 17 illustrates a schematic diagram of exemplary architecture reinforcing an offshore oilrig in accordance with the present invention;

Figure 18 illustrates a schematic diagram of an exemplary architecture for manufacturing engineered pipes in accordance with the present invention;

Figure 19 illustrates a schematic diagram of an engineering process used to induce and retain a curved pre-stress in a metal/alloy or advanced composite material in accordance with the present invention;

Figure 20 illustrates a schematic diagram of an engineering process used to induce and retain a curved pre-stress in an advanced composite material in accordance with the present invention; and

Figure 21 illustrates a schematic diagram of an engineering process used to induce a curved pre-stress in an advanced composite material in accordance with the present invention.

Detailed Description Of The Drawings The present invention relates to a system and method for enhancing the stored elastic strain energy of a structure to increase its capability to withstand external blast, pressure waves and/or projectiles. The invention comprises the application of a curved pre-stress force applied to enhance the stored elastic strain energy of a structure to increase its capability to withstand external blast and pressure waves. A curved pre-stress is applied to a material to increase tensile forces on one side of the material and compressive forces on the other side of the material. In doing so, the structure is more resistant to forces exerted onto the tensile side of the structure. An external force would have to invert the tensile force into compression and in addition, convert the compressive force into tension before the collapse process starts. The curved pre-stress is retained by the processes required to manufacture the structure. The structure may be incorporated into a system to protect a vulnerable part of a vehicular or building structure.

Figure 1 illustrates the manufacturing process of the curved pre-stress panels. A flat fibre reinforced plastic (FRP) panel (33) is heated up to a level such that the material becomes pliable (34). Force is then exerted onto the ends of the material (35) and an accelerated cooling process is placed on the internal side of the material (36) to induce the compressive forces on the internal side of the material (37) and to induce the tensile forces on the external side of the material (38). Once dry, a thin layer of metal (39) is adhered onto the tensile side of the structure to provide protection from the abrasion and particles present during a blast or pressure wave event

Figure 2 illustrates a schematic diagram of an exemplary architecture of integrated armour for the underbody of armoured land vehicles. The structure is comprised of; curved pre- stressed panel (1), a middle layer of spherically formed energy absorbing material (2) comprising the curved pre-stressing technique is incorporated, before an additional curved pre-stressed panel (3). The structure is affixed to the vehicle at fixing points (4), which may be by way of mechanically fastening the structure using brackets. Figure 3 illustrates a schematic diagram of an alternative exemplary architecture of integrated armour for the underbody of armoured land vehicles. The structure comprises an extruded oval form, forming a closed shape, incorporating the curved pre-stressing technique (5), and a middle layer of spherically formed energy absorbing material (2) comprising the curved pre-stressing technique of the present invention.

Figure 4 illustrates a schematic diagram of an exemplary architecture for retrofitted alloy armour for the underbody of armoured land vehicles. The structure comprises a curved pre-stressed metal or alloy (6) and the curved pre-stress is retained with the use of an external un-stressed frame (7), which is mechanically fastened to the pre-stressed metal or alloy.

Figure 5 illustrates a schematic diagram of an exemplary architecture for retrofitted advanced composite armour for the underbody of armoured land vehicles. The structure comprises a curved pre-stressed advanced composite material (8) in accordance with the present invention and the curved pre-stress is retained with the use of an external unstressed frame (9), which is mechanically fastened thereto. Figure 6 illustrates a schematic diagram of an exemplary architecture of armour constructed in accordance with the present invention affixed to the side of a vehicle to protect against projectiles. The structure comprises small-scaled curved pre-stressed elements (10), and is arranged in a repeatable method to enhance the stored elastic strain energy of the structure.

Figure 7 illustrates a domed construction used for a variety of applications on a micro and macro scale incorporating the curved pre-stress processes (11) of the present invention.

Figure 8 illustrates a schematic diagram of an exemplary architecture of a Building shelter. Curved pre-stressed panels (12) are formed at a scale, cost-effective and transportable for the product, and the curved pre-stress is made in accordance with the present invention and is retained with the use of mechanical fastening between each panel (13).

Figure 9 illustrates a schematic diagram of an exemplary architecture for a Protection Shield. Curved pre-stressed panels (14), which are made in accordance with the present invention, are formed at a scale, cost effective and transportable for the product, and pre- stress is retained with the use of mechanical fastening between each panel (15).

Figure 10 illustrates a schematic diagram of an exemplary architecture for a Personal Protection Shield. Curved pre-stressed panels (16) made in accordance with the present invention are formed at a scale, cost effective and transportable for the product, and the curved pre-stress is retained with the use of mechanical fastening at the ends of the panel (17). Figure 11 illustrates a schematic diagram of an exemplary architecture for Body Protection Armour. A curved pre-stressed panel (18) that is made in accordance with the present invention is formed around a human body engaging structure, such as a wearable item, for example, body armour, and is retained thereto through a thermal bonding process.

Figure 12 illustrates a schematic diagram of an exemplary architecture for enhancing the strength of the Sub-Structure of a Maritime Vessel. A curved pre-stressed panel in accordance with the present invention is stressed to enhance the stored elastic strain energy of a structure to withstand external blast and pressure waves (19). The curved pre-stressed panel is retained by mechanical fastening to the structure (20).

Figure 13 illustrates a schematic diagram of an exemplary architecture for increasing the stiffness in the hull of a Maritime Vessel. A structure is developed and designed incorporating the curved pre-stress technique as described (21) herein, to enhance the stiffness of the structure against tidal waves and to cut through water to present a more agile hull structure of a luxury yacht.

Figure 14 illustrates a schematic diagram of an exemplary architecture for reducing the weight of a Super-Structure of a Maritime Vessel. The superstructure is enhanced and made lighter by the use of the curved pre-stressing technique (22) that forms the present invention.

Figure IS illustrates a schematic diagram of an exemplary architecture for mitigating the effects of tunnel boom. Domed formed components of the curved pre-stressing technique (23) of the present invention are incorporated to absorb the energy generated from high speed travelling trains to mitigate noise pollution.

Figure 16 illustrates a schematic diagram of an exemplary architecture for reinforcing a tunnel.

Curved components (24) incorporating the curved pre-stressing technique of the present invention are utilized to strengthen a tunnel structure against external pressure.

Figure 17 illustrates a schematic diagram of an exemplary architecture for reinforcing an offshore oilrig. A curved pre-stressed circular component is extruded incorporating the curved pre-stressing technique (25) of the present invention, and is utilized to strengthen an offshore oilrig structure. In order to form this element, the circular component is forced through a die, after which is immediately subjected to a heating/cooling process. Cold air is rapidly projected onto the inside surface, whilst hot air is projected onto the outside surface so as to induce the tensile compressive forces onto the structure. Thus, the structure is put into a pre-stressed state. This is described further below, particularly in respect of Figure 19.

Figure 18 illustrates a schematic diagram of an exemplary architecture for manufacturing engineered pipes. A curved pre-stressed structure is extruded in a similar manner to that described in Figure 17, by use of the curved pre-stressing technique (26) of the present invention, by way of enhancing the protection of the pipe against external blast and pressure waves. Figure 19 illustrates a schematic diagram of a differential heating cooling engineering process used to induce and retain a curved pre-stress in a metal/alloy or advanced composite material. The material is heated on one side to induce tensile forces into the structure (27), and the material is cooled on one side to induce compression on the other side of the structure (28). This process is used for both 3D closed shell curved pre-stressed structures as well as open 2D structures. A second member is subsequently bonded to the pre-stressed material.

Figure 20 illustrates a schematic diagram of a differential textile weaving engineering process used to induce and retain a curved pre-stress in an advanced composite material., which constitutes a panel when the textile is held within resin. , The material is fabricated with a regular weave to induce a comparative tensile force on one side of the structure (29) and the material is fabricated with a tightened weave to induce a comparative compressive force onto the other side the structure (30). T is process is applicable for both 3D closed shell curved pre-stressed structures as well as open 2D structures. A second member is bonded to the pre-stressed panel.

Figure 21 illustrates a schematic diagram of a differential curing engineering process. A part resin is applied to the material (31), force is applied, and then further resin is applied (32) to induce a tensile force on one side of the structure and a compressive force on the other side of the structure, which forms a panel. This process is envisaged to be used for both 3D closed shell curved pre- stressed structures incorporating our technique as well as open 2D structures. A second member is then bonded to the finished pre-stressed panel.

The structure of the present invention may be made to any required size and may be readily transportable. It is envisaged that a plurality of panels in accordance with the present invention may be connected to a single unstressed framework in order to create an array of pre-stressed structures. Such an array may be employed for providing resistance to a large surface, such as a building.

Claims

A blast and pressure wave resistant structure comprising a first member and a second member, wherein the first member is a yieldably resilient panel that is deformed to create a curved portion therein, wherein the deformed panel has a convex surface and a concave surface, wherein the panel is retained in that deformed state and wherein the second member is bonded to the first member to create a protective layer therefor.

A blast and pressure wave resistant structure according to claim 1, wherein at least the first member is held around at least part of its perimeter within an unstressed frame and the unstressed frame retains the deformed first member in that deformed state.

A blast and pressure wave resistant structure according to any preceding claim, wherein a material is sandwiched between the first and second members.

A blast and pressure wave resistant structure according to any preceding claim, wherein the first and/or second member comprises at least one material selected from a group comprising: composite material; metallic material; plastics material; ceramic material; concrete; and polymer resin.

A blast and pressure wave resistant structure according to any preceding claim, wherein the second member is unstressed.

An item comprising the blast and pressure wave resistant structure of any preceding claim, wherein the convex surface of the first member is directed outwardly from the item and the concave surface is directed inwardly towards the item.

An item according to claim 6, wherein the blast and pressure wave resistant structure is incorporated into and/or applied to the item and the item is selected from a group comprising: a land vehicle; personal protection equipment; a building; a tunnel structure; an oil rig; a maritime vessel; a submarine; armour plating and a remotely operated underwater vehicle.

A method of making a blast and pressure wave resistant structure in accordance with any one of claims 1 to 5, wherein the method comprises the steps of: providing a first member in the form of a panel of material;

heating at least one portion of the panel of material;

providing a force to one or more locations on the panel of material;

providing a cooling fluid to one side of the panel of material to induce compressive forces of that one side of the panel and tensile forces of the other side of the panel, thereby deforming the panel of material such that a convex and concave side are formed therein; and attaching a second member to the first member. 9. A method according to claim 8, wherein heating of the panel continues whilst the cooling fluid is applied. 10. A method according to claim 8 or claim 9, wherein the force is provided to one or more edges of the panel of material. 11. A method according to any one of claims 8 to 10, wherein the first member, once the panel of material is deformed, is connected to an unstressed framework about at least part of the perimeter of the panel of material.