WO2019079852A1

WO2019079852A1 - Microlattice shield

Info

Publication number: WO2019079852A1
Application number: PCT/AU2018/051149
Authority: WO
Inventors: Jack C Swan; Cameron H Busch
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-10-24
Filing date: 2018-10-24
Publication date: 2019-05-02
Anticipated expiration: 2020-04-24

Abstract

L'invention concerne un blindage à micro-treillis (100) comprenant : une couche de blindage avant (110) ou une couche de blindage arrière (140) ; et un micro-treillis (120) adjacent à la couche de blindage avant (110) ou à la couche de blindage arrière (140), et dans un mode de réalisation, le blindage à micro-treillis (100) comprend la couche de blindage avant (110) et la couche de blindage arrière (140), et le micro-treillis (120) est situé entre la couche de blindage avant (110) et la couche de blindage arrière (140).The invention relates to a micro-trellis shield (100) comprising: a front armor layer (110) or a rear armor layer (140); and a micro-trellis (120) adjacent to the front shielding layer (110) or rear shielding layer (140), and in one embodiment, the micro-trellis shield (100) comprises the shielding layer front (110) and the rear armor layer (140), and the micro-trellis (120) is located between the front armor layer (110) and the rear armor layer (140).

Description

TITLE

MICROLATTICE SHIELD

FIELD OF THE INVENTION

[0001 ] The present invention relates to a microlattice shield and, in particular, a layered microlattice shield for dissipating the direct or fragmented force of impacting hyper and high velocity projectiles.

BACKGROUND TO THE INVENTION

[0002] Existing technologies for protection from high velocity projectiles, ranging from shrapnel to bullets to space debris, small near Earth objects and meteoroids, commonly include synthetic para-aramid fibres (commonly known as Kevlar) which have remarkably high tensile strength-to-weight ratio and are 5 times stronger than steel.

[0003] When woven together in an interlocking structure, these synthetic para-aramid fibres can stop bullets and other similar projectiles which would otherwise cause serious damage, injury or death, depending on the target.

However, to be effective, the synthetic para-aramid fibres must be woven into a tight cloth before being integrated into a vest or fibreglass panel, for example.

[0004] If the fibres are not properly woven, projectiles will easily slip between the fibres and cause injury or damage. In a fibreglass panel application, the resin in the fibreglass panel stiffens the layers of cloth which both ensures that the fibres provide a rigid stop for the bullets and protects the fibres from exposure to the elements, chemicals, and especially water, which detrimentally and adversely impacts the effectiveness of the para-aramid fibres. In the event that the fibres are compromised by water, the effectiveness of the fibres to stop the projectiles is lessened and the projectiles may be able to penetrate the woven fibres or result in dangerous blunt force trauma injuries.

[0005] Other methods also exist for improving penetration resistance against high velocity projectiles by using high strength materials applied in layers, such as dense metals. However, these materials can add significant weight to the shielding structure and adversely affect movement and increase costs.

[0006] Another method of improving penetration resistance against high and hyper velocity projectiles exists in inducing a rotational motion into the projectile while passing through the shield. The act of transforming a percentage of the linear velocity partially into a rotational velocity is common referred to as

"projectile tumbling". The abovementioned method further dissipates projectile energy through a combination of effects including but not limited to; increased leading edge exposure to impact absorbing material and reduced aerodynamic efficiency.

[0007] One existing method of projectile resistance used previously in spacecraft exists in a plurality of plates or similar layers separated by optimised gaps. In some embodiments, this method also uses projectile resistive materials such para-aramid fibres or Kevlar or sacrificial energy absorbent layers. This design has shown some limited success in protecting spacecraft. Elements of this document contain improvements on this design focusing on increased projectile resistance and mass reduction.

[0008] It is an advantage of at least one embodiment of the present invention to provide a microlattice shield that addresses, or at least ameliorates one or more of the aforementioned problems of the prior art and/or provides a useful commercial alternative. SUMMARY OF THE INVENTION

[0009] In one form, although not necessarily the only or broadest form, the invention resides in a microlattice shield comprising: a front shield layer or a rear shield layer; and a microlattice located adjacent the front shield layer or the rear shield layer.

[0010] In one embodiment, the microlattice shield may have either the front shield layer or the rear shield layer, and the microlattice. The shield comprises the microlattice adjacent to either the front shield layer or rear shield layer depending on which is present. In an alternative embodiment, the microlattice shield has both the front shield layer and the rear shield layer. In this alternative

embodiment, the microlattice is located between the front shield layer and the rear shield layer.

[001 1 ] In some embodiments, the front shield layer and the microlattice are spaced apart. Additionally, or alternatively, the rear shield layer and the microlattice are spaced apart.

[0012] It is preferable that the microlattice shield further comprises one or more catchment layers. Preferably, the catchment layers are located between the front shield layer and the rear shield layer adjacent the microlattice. Suitably, the catchment layers comprise an aramid fibre or carbon fibre. More suitably, the catchment layers comprise a para-aramid synthetic fibre, such as Kevlar, for example.

[0013] Suitably, the microlattice comprises a plurality of unit cells having a plurality of unit members. [0014] In some preferable embodiments, the unit cells are base centred cubic (BCC), face centred cubic, close packed hexagonal, triangular or spherical in shape. The unit cells may have a varying base geometry that transition for example from BCC to spherical. A varying base geometry may further improve projectile resistance.

[0015] Preferably, the unit cells of the microlattice are uniform. Alternatively, unit cells of the microlattice are non-uniform.

[0016] Each unit member of a unit cell is preferably uniform. Alternatively, each unit member of a unit cell is non-uniform. In some preferred embodiments, each unit member of a unit cell are hollow. There may be some unit members that are hollow and some that are not.

[0017] Preferably, the microlattice is formed by 3D printing or additive manufacturing.

[0018] Preferably, the front shield layer or the rear shield layer each comprise at least one of metal, ceramic, plastic or composite materials. In some preferable embodiments, the front shield layer and the rear shield layer comprise carbon fibre, aramid fibre or para-aramid synthetic fibre.

[0019] In some embodiments, part or all of the shield layers may comprise shape memory materials such as nickel titanium (nitinol). Further hardware maybe added to the shield in these embodiments such as hardware to support heat cycling the material of the shield layers in order to return the shield to its non-deformed geometric dimensions. This may be provided in the form of a device to pass electrical current through the shield, using the heat generated by the materials' electrical resistance to heat cycle the material. [0020] In other embodiments, the shield layers be comprised of lightweight materials such as graphene, carbon nanotubes or similar developmental materials.

[0021 ] In some embodiments, the microlattice is attached to the front shield layer or the rear shield layer.

[0022] Preferably, the layers are attached to the microlattice by glue, welding, clamps, screws and threaded sections.

[0023] In some alternative embodiments, the microlattice shield may be in a form comprising at least two distinct shield layers or a single integrally formed layer.

[0024] Preferably, the microlattice comprises at least one of metal, ceramic, plastic and composite materials.

[0025] In another form, the invention resides in a method of forming a microlattice shield, the method comprising the steps of: providing a rear shield layer or a front shield layer; and forming a microlattice adjacent to the rear shield layer or the front shield layer.

In some embodiments, the method comprises the further step of forming the microlattice by 3D printing or an additive manufacturing process.

[0026] Preferably, the method comprises the further step of treating the microlattice or shield layers using a post-manufacturing process. [0027] In some embodiments, the shield layers may serve secondary function as a storage medium (water tank for example) for gases, liquids, solids or gels. The contained materials may function to further increase the projectile resistance of the overall shield in addition to the purpose of carrying, containing or transporting those materials.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, in which:

[0029] FIG. 1 illustrates a perspective view of a microlattice shield according to an embodiment of the present invention;

[0030] FIG. 2 illustrates a side view of the microlattice shield of FIG. 1 ;

[0031 ] FIG. 3 illustrates a perspective of a microlattice shield according to a second embodiment of the present invention; and

[0032] FIG. 4 illustrates a side view of the microlattice shield of FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

[0033] Elements of the invention are illustrated in concise outline form in the drawings, showing only those specific details that are necessary to understanding the embodiments of the present invention, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description. [0034] Embodiments of the present invention provide a lightweight and improved shielding structure for protection from high velocity projectiles, such as bullets and space debris, using a microlattice structure.

[0035] An advantage of this is that the microlattice dissipates the impacting force of projectiles through the fracturing and compression of the individual members of the microlattice. In a further advantage, the microlattice will return to shape if the deformation is below the elastic limit of the material. Otherwise, if deformation exceeds the elastic limit of the material, members of the microlattice will fail, further dissipating energy.

[0036] In another advantage, the use of a lightweight microlattice provides a reduction in the overall shield mass.

[0037] Turning to FIG. 1 , there is illustrated a perspective view of a

microlattice shield 100 for reducing or preventing damage and injuries caused by high velocity projectiles.

[0038] The microlattice shield 100 includes a front shield layer 1 10, a microlattice 120, an intermediate catchment layer 130 and a rear shield layer 140.

[0039] As can be seen, the microlattice 120 and the catchment layer 130 are located between the front shield layer 1 10 and the rear shield layer 140.

[0040] The front shield layer 1 10 and the rear shield layer 140 act as skins located on the outer sides of the shield 100, and are formed from materials such as aramid fibres, para-aramid synthetic fibres, such as Kevlar, for example, metals, ceramics and plastics, or composites of these materials.

[0041 ] In some embodiments, the front shield layer 1 10 and the rear shield layer 140 can include existing infrastructure, such as the metal skins in a car door, or the outer layer of a boat's hull, for example, to allow retrofitting or in-situ fitting of the shield 1 10 to existing vehicles and infrastructure. In use, the front shield layer 1 10 is designed to break up projectiles and disperse the particles. In this regard, the front shield 1 10 is responsible for both breaking up (either through liquidation or projectile shattering) and reducing the energy and velocity of the remaining projectiles, such as armour piercing bullets, and/or fragments which then impact the microlattice 120.

[0042] The microlattice 120, a synthetic porous material resembling an ultralight foam, is formed from many individual unit cells. Each cell typically has a generally base centred cubic-Z lattice or diamond lattice shape, which makes the material ideal for absorbing impacts. The microlattice 120 is particularly effective in dissipating the force of hyper velocity or high velocity objects.

[0043] The microlattice 120 can be formed through a variety of techniques, including 3D printing or additive manufacturing methods, for example.

[0044] In some embodiments, the individual unit cells can be different shapes, including base centred cubic, face centred cubic, close packed hexagonal, triangular and spherical, for example, for specific application. Additionally, the unit members within each cell can have different cross sections. As a result, not all members are the same thickness and each member can narrow or widen along its own length.

[0045] Further to this, the unit cell can contain variations beyond typical shapes such as additional optimised members (for example an additional vertical member in a cubic structure) and variation of the unit cell's aspect ratio. This can further increase the penetration resistance of the material and optimise

characteristics of the material as an overall structure (for example refine the axis of which the material as a sheet is flexible within). Additionally, optimisation of the individual members within the unit cell can be achieved through varying the size of the cross sectional area of the individual members along their respective length. This includes potentially creating hollow members. [0046] Optimised nodes can also be used at the joining junctions of multiple members, including the use of geometry such as oversized spheres placed centrally to the node in some embodiments.

[0047] Furthermore, the structural proportions of the microlattice 120 can vary depending on the application, for example some shield products can employ a microlattice 120 having a depth of only two unit cells, while other shield products can employ a microlattice 120 having a depth of dozens of unit cells and beyond.

[0048] The volume of a singular unit cell may change through the thickness of the micro-lattice 120 resulting in a progressive unit cell size through the cross section of the sheet. An example of this would be having a multiple order of magnitude smaller unit cell on the side of the microlattice 120 that would be initially impacted, resulting in a greater number of unit cells on the leading edge with greater potential to dissipate energy. The unit cell volume would

progressively increase through to a larger unit cell on the rear that would be able to catch and/or slow the remaining fragments. A design of this nature can be employed to further optimise either material performance or to reduce the overall mass of the shield. The design described above can alternatively include a microlattice 120 with progressively decreasing unit cell volume rather than an increasing volume, as described above.

[0049] Further, individual unit members or unit cells may be selectively weakened (either during or post manufacturing) to induce projectile rotation (tumble) or to guide the projectile as it passes through the cross section of the shield. This method can be used to further remove energy from the projectile primarily by exposing increased surface area of the projectile to the shield, beyond just the leading edge of the projectile and further, the aerodynamic impact rotating.

[0050] The front shield 1 10, 210 may also be selectively strengthened or weakened (either during or post manufacturing) to induce projectile rotation (tumble) and / or change projectile angle of impact into microlattice 120 and / or 210.

[0051 ] The microlattice 120 can also have further post-manufacturing treatment, such as stress relief, recrystallization and hot isostatic pressing, for example, to improve material properties.

[0052] Located between the rear shield 140 and the microlattice 120 is the catchment layer 130 which catches any fragments that make it through the microlattice 120. For example, the catchment layer 130 can catch both original projectile fragments and pieces that penetrate through failed preceding layers.

[0053] In order to maximise the shielding effect of the microlattice shield 100, the catchment layer 130 can be formed from a material similar to the front shield layer 1 10 and rear shield layer 140, or can also be formed from a penetration resistant material, such as a para-aramid synthetic fibre or carbon fibre.

[0054] In forming the microlattice shield 100, each of the layers 1 10, 130, 140 and microlattice 120 can be attached or secured together by glue, welding, clamps, screws and threaded sections. Alternatively, some or all of the layers 1 10, 120, 130, 140 can also be integrally formed. A combination of integrally forming and the above mentioned attachment methods may be preferable for forming the microlattice shield 100 in some instances.

[0055] Turning to FIG. 2, the base centred cubic-Z or diamond lattice shape of the individual unit cells of the microlattice 120 can be more clearly seen.

[0056] In another embodiment, shown in FIG. 3, there is illustrated a microlattice shield 200 having a front shield layer 210, a microlattice 220, a catchment layer 230 and a rear shield layer 240, which are as substantially described in relation to the microlattice shield 100 of FIG. 1 . However, it will be appreciated from the figure that each of the layers of microlattice shield 200 are separated by spaces in the form of air gaps (no air in the case of a space craft shield).

[0057] The selective spacing between the various layers further aids the penetration resistance of the microlattice shield 200 by allowing any debris, which penetrates the front shield layer 210 after the initial impact, to spread out and lose further velocity and energy before impacting the microlattice 220. The spacing can also further refine the weight distributions and weight savings for the specific application.

[0058] While each layer of the microlattice shield 200 is shown as being separated from the adjacent layer by a gap in the illustrated embodiment, it will be appreciated that some layers can be separated while others are abutting and have no spacing between them.

[0059] With reference to FIG. 4, the spacing between each of the layers of the microlattice shield 200 can be more clearly seen. In the illustrated embodiment, a larger gap is provided between the front shield layer 210 and the microlattice 220 to allow additional space for any debris or projectile that penetrates the front shield layer 210 to disperse and slow down.

[0060] The following describe some particular examples and applications of the microlattice shields 100, 200 described above.

[0061 ] In a first example, a microlattice shield 100, 200 can be used as for shielding space equipment, including space vehicles, rovers, mining equipment, satellites and space stations, for example, from space debris such as meteoroids. One exemplary structure for this type of shielding consists of:

Front shield Gap

Microlattice

Kevlar (catchment layer)

Rear Shield

[0062] This structure is designed for high - hyper velocity impacts from space debris such as parts from old satellites, meteoroids and projectiles. It will be appreciated that the layering may not be exactly the same as described above (e.g. further gaps may be used between any of the layers).

[0063] In this particular embodiment, the gap allows debris from the initial impact to spread out and lose further velocity and energy before impacting the microlattice 120, 220.

[0064] Furthermore, the rear shield provides multiple functions, including acting as an additional layer of protection, providing an air tight surface in the context of a space craft and acting as structural support for the microlattice 120, 220. It will be appreciated that the rear shield can also be a wall of a spacecraft or other space equipment in some particular embodiments.

[0065] Another application of the microlattice shield 100, 200 described above resides in installing the microlattice shield 100, 200 in passenger vehicles and existing infrastructure, such as a panel on a door, for example. An example of the microlattice shield structure for this application is shown below: Front shield

Microlattice

Kevlar (catchment layer)

Rear shield

[0066] This particular application of a microlattice shield 100, 200 can reside in a panel (for example a metallic inner door skin) and the interior materials of the vehicle or existing infrastructure where the door panel, for example, forms the front shield and the inner portion of the panel forms the rear shield..

[0067] This embodiment can also be applied for use in, for example, boats, aircraft, satellites and space vehicles. In the context of a boat, the hull forms the front shield layer, for example.

[0068] Gaps or spacing may be used between any layers as per the space debris application above to improve resistance to penetration by projectiles.

[0069] In another particular embodiment, the microlattice shield structure described above can be used in armoured vehicle applications by replacing the front and rear shields with material which provides bullet resistance.

[0070] In another variation, the microlattice shield 100, 200 can be used with boats, ships, amphibious vehicles and the like by forming the front and rear shields of waterproof materials such as panels, ports and hulls. [0071 ] In summary, embodiments of the present invention provide improved shielding from high velocity projectiles using a microlattice structure.

Embodiments of the present invention can also provide reduced overall mass of shielding devices through the reduced reliance on heavy penetration resistant materials, such as steel.

[0072] In another embodiment, a microlattice shield may be provided with more than three layers, for example, comprising a microlattice, a plate and a microlattice plate.

[0073] In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or a step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step, etc.

[0074] Further, in this specification, the terms 'comprises', 'comprising', 'includes', 'including', or similar terms are intended to mean a nonexclusive inclusion, such that a method, system, or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

[0075] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed

specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. [0076] The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

[0077] While the term "microlattice" has been used throughout the description, in some embodiments the scale of the unit cells and unit members comprising a lattice structure may exceed or fall under a "micro level" of scale, in other words, the lattice structure may simply be small comprising at the nanometre scale, millimetre scale or centimetre scale.

Claims

1 . A microlattice shield comprising:

a front shield layer or a rear shield layer; and

a microlattice located adjacent to the front shield layer or the rear shield layer.

2. The microlattice shield according to claim 1 , wherein the microlattice shield comprises the front shield layer and the rear shield layer, and the microlattice located between the front shield layer and the rear shield layer.

3. The microlattice shield according to claim 1 , wherein the front shield layer and the microlattice or the rear shield layer and the microlattice are in a spaced apart relationship.

4. The microlattice shield according to claim 2, further comprising at least one catchment layer.

5. The microlattice shield according to claim 4, wherein the at least one catchment layer is located between the front shield layer and the rear shield layer adjacent the microlattice.

6. The microlattice shield according to claim 4, wherein the at least one catchment layer comprises any one from the group consisting of: aramid fibre, carbon fibre, and para-aramid synthetic fibre.

7. The microlattice shield according to claim 1 , further comprising a plurality of unit cells having a plurality of unit members.

8. The microlattice shield according to claim 7, wherein the unit cells are base centred cubic (BCC), face centred cubic, close packed hexagonal, triangular or spherical in shape.

9. The microlattice shield according to claim 8, wherein the unit cells of the microlattice are uniform.

10. The microlattice shield according to claim 8, wherein each unit member of a unit cell is uniform.

1 1 . The microlattice shield according to claim 8, wherein each unit member of a unit cell is hollow.

12. The microlattice shield according to claim 1 , wherein the microlattice is formed by 3D printing or additive manufacturing.

13. The microlattice shield according to claim 1 , wherein the front shield layer or the rear shield layer each comprise at least one of metal, ceramic, plastic or composite materials.

14. The microlattice shield according to claim 1 , wherein the front shield layer or the rear shield layer each comprise carbon fibre, aramid fibre or para-aramid synthetic fibre.

15. The microlattice shield according to claim 1 , wherein at least part of the shield layers comprise shape memory materials such as nickel titanium (nitinol).

16. The microlattice shield according to claim 15, further comprising a heat cycling device configured to provide heat cycling the material of the shield layers in order to return the shield to its non-deformed geometric dimensions.

17. The microlattice shield according to claim 2, wherein the microlattice shield is in a form comprising at least two distinct shield layers or a single integrally formed layer.

18. The microlattice shield according to claim 1 , wherein the microlattice comprises at least one of metal, ceramic, plastic or composite materials.

19. A method of forming a microlattice shield, the method comprising the steps of:

providing a rear shield layer or a front shield layer; and

forming a microlattice adjacent to the rear shield layer or the front shield layer.

20. The method according to claim 19, further comprising the step of forming the microlattice by 3D printing or an additive manufacturing process.

21 . The method according to claim 19, further comprising the step of treating the microlattice or shield layers using a post-manufacturing process.