WO2005008163A2

WO2005008163A2 - Ballistic panel

Info

Publication number: WO2005008163A2
Application number: PCT/IL2004/000660
Authority: WO
Inventors: David Cohen
Original assignee: David Cohen
Priority date: 2003-07-20
Filing date: 2004-07-20
Publication date: 2005-01-27
Also published as: WO2005008163A3; IL157017A0

Abstract

A ballistic panel comprises a first layer of ballistic material and a second layer of energy absorbing material. The second layer in turn comprises a first sub-layer of relatively soft material and a second sub-layer of relatively hard material.

Description

Ballistic panel

FIELD AND BACKGROUND OF THE INVENTION The present invention relates to a ballistic panel. Ballistic panels are used to stop bullets and may be incorporated into bulletproof clothing and the like. Bullets are graded in levels, in terms of the level of difficulty in stopping the bullet. Level 1 covers the 0.22" handgun low velocity ammunition as found in sports rifles and the like. Level 2, covers 9mm standard ammunition and level 3 covers high velocity ammunition such as the AK-47, M80, (Natoball), and Ml 6 ammunition One material commonly used in ballistic panels intended for level three ammunition is the material know as Spectra, sold by Honeywell International Inc. Polythene, compressed at high temp, and then made into a laminate, stops bullets of level three. Spectra is not a woven fabric like most ballistic materials such as Kevlar©.

Rather it is a High modulus polyethylene fiber, which comprises a thin, flexible ballistic composite made from layers of unidirectional fibers held in place by flexible resins or for example by fusion of the fibres. These fibers are arranged so they cross each other at 0 and 90 degree angles, then, both fiber and resin layers are sealed between two thin sheets of polyethylene film in a manner similar to saran wrap. Today, densities of around 21kg M (give or take about 2kg/M) of the high modulus polyethylene fiber are needed to consistently stop these bullets. Such densities are regular densities of the material as manufactured. The densities are to conform to US and International standards which set levels of penetration of bullets and the accompanying trauma to the body. Trauma occurs when the bullet itself does not enter the body but the shielding material deforms under impact of the bullet and the deformation impacts the body. The result is usually a hard knockout blow but can be fatal at sensitive parts of the body. Trauma is defined in the standards in terms of millimeters of deformation of the material. The current art uses ballistic panels which are entirely made of laminated layers of such high modulus polyethylene fiber. The material is expensive and even with these densities the trauma level is relatively high. There is thus a widely recognized need for, and it would be highly advantageous to have, a ballistic panel devoid of the above limitations.

SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a ballistic panel comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sub-layer of relatively soft material and a second sub-layer of relatively hard material. According to a second aspect of the present invention there is provided a method of manufacturing a ballistic panel comprising: providing a layer of high modulus polyethylene fiber, providing thereon a layer of relatively soft energy absorbing material, providing on said relatively soft energy absorbing material a layer of relatively hard energy absorbing material.

According to a third aspect of the present invention there is provided a method of manufacturing a ballistic panel to reduce structural damage to an initial stopping layer, the method comprising: providing an initial stopping layer of high modulus polyethylene fiber, providing thereon a layer of relatively soft energy absorbing material, providing on said relatively soft energy absorbing material a layer of relatively hard energy absorbing material. According to a further aspect of the present invention there is provided a method of upgrading a ballistic panel of polythene laminate having a given density, the method comprising: adding to said panel a strike layer, and adding to said panel an absorptive layer. According to a further aspect of the present invention there is provided a method of upgrading a ballistic panel of polythene laminate having a given density, the method comprising adding to said panel a strike layer. According to a yet further aspect of the present invention there is provided a method of upgrading an existing ballistic panel insert of polythene laminate having a given density, the method comprising adding to said panel a strike layer. According to a further aspect of the present invention there is provided a kit of parts for constructing a composite ballistic panel, the kit comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sub-layer of relatively soft material and a second sub-layer of relatively hard material, said layers being for forming said composite. According to a yet further aspect of the present invention there is provided a ballistic panel comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sub-layer of spacing material and a second sub-layer of relatively hard material. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. In the drawings: FIG. 1 is a simplified cross section showing the layers of materials in a ballistic panel according to a first embodiment of the present invention; FIG. 2 is a simplified cross section showing deformation due to impact from a bullet on the layers of the material of Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present embodiments show a ballistic panel comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sub-layer of relatively soft material and a second sub-layer of relatively hard material. The principles and operation of a ballistic panel according to the present invention may be better understood with reference to the drawings and accompanying descriptions. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. Referring now to the drawings, Figure 1 illustrates the material itself. A first layer 10 of high modulus polyethylene fiber is placed on a layer 12 of sponge which in turn is placed on a layer of polycarbonate 14. The fiber is a ballistic material and the sponge and polycarbonate are energy absorbing materials. Fig. 2 shows the effect of impact of a bullet on the materials. The bullet deforms each of the materials in turn. In the prior art the fiber loses properties and the bullet disintegrates. The energy absorbing materials of the present invention appear to cushion the impact and spread the deformation, having three major effects. Firstly the speed of the bullet is reduced without any significant initial deformation as the soft material deforms. Then, only subsequently to the initial impact, the bullet begins to be significantly deformed. The polycarbonate significantly limits the movement of the panel and also protects the Dynema from area mechanical damage. At the same time the Dynema absorbs the energy of the bullet and causes its partial or full disintegration. This applies for example to an M80 bullet. Secondly, a lower density of the fiber is sufficient to stop penetration of the bullet. In the present embodiments a mere 13 or even 12kg/m, made as an insert under the regular conditions is sufficient to stop an M80 bullet according to the NIJ trauma requirements. Thus the cost of the product is sharply reduced. However, it is possible to use the original 22-22kg/m density in order to further reduce the level of trauma and to provide a higher level of protection against multiple bullet impacts. It is possible using such densities to reduce the trauma to a minimal level, and is more likely to allow a person to continue functioning after the impact of the bullet, currently possible but uncommon with state of the art bullet proof vests. The sponge is preferably medium density synthetic sponge, is preferably compressed to form the layer and is preferably provided at thicknesses of around 4mm. In excess of 8mm the sponge does not have the necessary effect in affecting the deformation of the fiber layer. The polycarbonate is preferably provided in a 4mm layer or in two smaller layers making up 4mm between them. An example test was carried out to demonstrate a situation in which using a given density quantity of Dynema is insufficient by itself to stop the bullet but the same quantity of Dynema reinforced with other layers in accordance with the present embodiments is sufficient. In the test, which was carried out on 22 June, 2004 at the French National Ballistic Laboratories, Saint Etienne, France, standard M80 Nato ammunition was fired at a ballistic board comprising 12kg dynema in an NIJ test. The board did not stop the ammunition. The experiment was repeated with 4mm polycarbonate set up in front as a strike plate and 4mm sponge set up behind as an absorption plate. This time the ammunition was stopped with minimal trauma. More specifically a panel of 25 x 30 cm, as an insert to a Kevlar vest, had 6 bullets fired at it, which were stopped in statistically significant manner. Both as an insert to a Kevlar vest and as a standalone panel, the multi-layer construction achieves improvement in ballistic capabilities. The strike and absorption layers give mechanical support to the Dynema panel to allow the material to operate in the optimal way. The sponge layer may actually contain sponge or any other material with the ability to absorb energy, for example any elastic material. The composite of the present embodiments can be used as a backing for other materials, say ceramics. That is to say the ceramics are the initial strike face. In the past, small quantities of polycarbonate were used to reduce the trauma to the user, but the present embodiments use polycarbonate in a different way, namely it uses a critical amount of polycarbonate so as to improve the stopping power of the total composite. The composite uses less of the expensive Dynema material, but achieves the same stopping power due to its reinforcement with other, cheaper materials. In addition to reducing the cost for the same stopping power, the composite in any case reduces both the depth and the radius of the trauma. A further preferred embodiment of the present invention uses an additional layer of dynema, That is a composite is constructed that uses a first layer of compressed dynama (laminate), a second layer which is polycarbonate or sponge, a third layer which is the other of polycarbonate and sponge and then a final layer of Dynema. As a further alternative the second and third layers can be replaced by a single layer of either of the two. The layer of polycarbonate is greater than or equal to 4mm. Mechanical stability of unreinforced Dynema after an impact event is weak, and only gets worse with the number of hits. However, the use of a layer sufficiently thick of polycarbonate restores the stability of the Dynema, but also leaves it with its initial flexibility. Thus the polycarbonate effectively reinforces the mechanical structure of the dynama. A layer of sponge then limits the amount of motion, and again improves the stability of the Dynama. More particularly the sponge serves to spread or dissipate energy. It is noted that SSI 09 standard ammunition is now becoming standard issue and penetrates existing polythene panels. Thus much ballistic board type material is being rendered obsolete. The present embodiments allow the ballistic boards to be used in composites that can stop SSI 09 ammunition. As well as polycarbonate, outer layers of say, Aluminium, preferably 7075 T6 preferably Alklad 4.8mm or other kinds of aluminium having similar mechanical properties, can be used to upgrade the existing mostly polythene inserts. Additionally, instead of aluminium, it is possible to use titanium or any other material that adds stopping ability that the initial insert was not intended to have. Most Dynema and other like panels are of densities of 17kg +- 3kg. The composites of the present invention however give an integral panel which uses much less dynema but achieves the same stopping power. Thus using an Aluminium strike face with dynema, allows one to use less dynema than in the known art, and additional placement of sponge between the aluminium and the dynema provides for effective stopping of SSI 09 ammunition. An insert according to the present embodiments can carry out effective stopping of types of standard ammunition with as little as 12Kg of

Dynema. It is noted that it is also possible to provide the layers separately, for example as a kit of parts, and allow the end user to construct the composite he requires as and when needed. As used herein the term "about" refers to ± 25 %. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

Claims

WHAT IS CLAIMED IS:

I . A ballistic panel comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sublayer of relatively soft material and a second sub-layer of relatively hard material.

2. The panel of claim 1 , wherein said ballistic material is a high modulus polyethelene fiber.

3. The panel of claim 2, wherein the first sub-layer comprises sponge.

4. The panel of claim 2, wherein said first sub-layer comprises an elastic material.

5. The panel of claim 3, wherein the second sub-layer comprises polycarbonate.

6. The panel of claim 5, wherein said second sub-layer comprises at least two layers of polycarbonate.

7. The panel of claim 5, comprising a quantity of said high modulus polyethylene fiber selected for a predetermined threat.

8. The panel of claim 7, wherein said first sub-layer is at least 2mm.

9. The panel of claim 7, wherein said second sub-layer is at least 2mm.

10. The panel of claim 7, wherein said first sub-layer is substantially 4mm in thickness.

I I . The panel of claim 7, wherein said second sub-layer is substantially 4mm in thickness.

12. The panel of claim 1 , wherein said first sub-layer is substantially 4mm in thickness.

13. The panel of claim 1, wherein said second sub-layer is substantially 4mm in thickness.

14. The panel of claim 1 , arranged as a backing for a ceramic layer.

15. The panel of claim 1 , wherein one of said layers is a laminate of compressed polythene.

16. The panel of claim 15, wherein one of said layers is polycarbonate.

17. The panel of claim 16, wherein one of said layers is aluminium.

18. The panel of claim 1 , wherein one of said layers is a laminate of compressed polythene, at a density of 17kg/m or less and one of said layers is substantially 4mm of polycarbonate.

19. The panel of claim 18, comprising an additional layer of said laminate of compressed polythene.

20. A method of manufacturing a ballistic panel comprising: providing a layer of high modulus polyethylene fiber, providing thereon a layer of relatively soft energy absorbing material, providing on said relatively soft energy absorbing material a layer of relatively hard energy absorbing material.

21. The method of claim 20, wherein said layer of high modulus energy absorbing fiber is at a density of 17kg/m or less.

22. The method of claim 20, wherein said relatively soft energy absorbing material comprises sponge.

23. The method of claim 20, wherein said relatively hard energy absorbing material comprises polycarbonate.

24. The method of claim 20, wherein said relatively hard energy absorbing material comprises aluminium.

25. The method of claim 24, wherein said aluminium is strengthened aluminium.

26. The method of claim 25, wherein said strengthened aluminium comprises 7075 T6 strengthened aluminium.

27. A method of manufacturing a ballistic panel to reduce structural damage to an initial stopping layer, the method comprising: providing an initial stopping layer of high modulus polyethylene fiber, providing thereon a layer of relatively soft energy absorbing material, providing on said relatively soft energy absorbing material a layer of relatively hard energy absorbing material.

28. The method of claim 27, wherein said providing said initial stopping layer comprises selecting a thickness thereof which is sufficient in combination with said other layers to meet a predefined threat.

29. A method of upgrading a ballistic panel of polythene laminate having a given density, the method comprising: adding to said panel a strike layer, and adding to said panel an absorptive layer.

30. The method of claim 29, wherein said strike layer is polycarbonate.

31. The method of claim 29, wherein said absorptive layer is one of a sponge and an elastic material.

32. The method of claim 29, wherein said strike layer comprises aluminium.

33. The method of claim 32, wherein said aluminium is below 6mm.

34. The method of claim 32, wherein said aluminium is substantially 4.8mm in thickness.

35. The method of claim 32, further comprising adding a layer of ceramic.

36. A method of upgrading a ballistic panel of polythene laminate having a given density, the method comprising adding to said panel a strike layer.

37. A method of upgrading an existing ballistic panel insert of polythene laminate having a given density, the method comprising adding to said panel a strike layer.

38. The method of claim 37, further comprising adding to said panel a layer of absorptive material.

39. The method of claim 37, wherein said strike layer comprises hardened aluminium.

40. The method of claim 37, comprising adding a layer of ceramic.

41. A kit of parts for constructing a composite ballistic panel, the kit comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sub-layer of relatively soft material and a second sub-layer of relatively hard material, said layers being for forming said composite.

42. A ballistic panel comprising a first layer of ballistic material and a second layer of energy absorbing material, said second layer comprises a first sublayer of spacing material and a second sub-layer of relatively hard material.