Multi-layer armor having lateral shock transfer

Abstract

Armor includes a projectile impermeable material layer and a shock stiffening layer. The shock stiffening layer has opposing shock stiffening sublayers wherein each shock stiffening sublayer has a plurality of shock stiffening sublayer elements. The plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers are interdigitated. The armor includes a foam layer wherein the shock stiffening layer is positioned between the foam layer and the projectile impermeable material layer. The plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers may momentarily or permanently fuse in response to a projectile's impact. The shock stiffening layer spreads the energy laterally, thereby effectively mitigating the transfer of kinetic energy from a ballistic projectile directly to a region to be protected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating a preferred embodiment and are not to be construed as limiting the present invention, wherein:

FIG. 1 illustrates an embodiment of conventional body armor;

FIG. 2 illustrates an embodiment of body armor according to the concepts of the present invention;

FIG. 3 illustrates an embodiment of body armor according to the concepts of the present invention;

FIG. 4 illustrates an embodiment of a shock stiffening layer for body armor according to the concepts of the present invention;

FIG. 5 illustrates another embodiment of a shock stiffening layer for body armor according to the concepts of the present invention;

FIG. 6 illustrates another embodiment of a shock stiffening layer for body armor according to the concepts of the present invention;

FIG. 7 illustrates a pre-impact shock stiffening layer for body armor according to the concepts of the present invention;

FIG. 8 illustrates a momentarily fused shock stiffening layer for body armor according to the concepts of the present invention; and

FIG. 9 illustrates a fused shock stiffening layer for body armor according to the concepts of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention will be described in connection with preferred embodiments; however, it will be understood that there is no intent to limit the present invention to the embodiments described herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention as defined by the appended claims.

For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference have been used throughout to designate identical or equivalent elements. It is also noted that the various drawings illustrating the present invention are not drawn to scale and that certain regions have been purposely drawn disproportionately so that the features and concepts of the present invention could be properly illustrated.

FIG. 1 illustrates an embodiment of conventional body armor. The conventional body armor includes a layer 20 of a projectile impermeable material, such as Kelvar™. When a projectile 10 encounters the projectile impermeable material layer 20, the projectile 10 transfers its kinetic energy to the projectile impermeable material layer 20. This transfer of kinetic energy is further transferred to the underlying tissue in the form of shock waves 30.

As noted above, the transfer of kinetic energy to the underlying tissue can cause damage to the tissue, resulting in injury or death. More specifically, if a projectile hits near the heart, the impact may cause death because relatively minor blunt trauma in that area of the chest, even at levels that do not result in visibly damaged surface tissue, can result in a spontaneous cardiac death. Moreover, as noted above, the transfer of kinetic energy to the underlying tissue can effect the time needed for an individual to recover from the impact so that the individual can effectively respond defensively or offensively.

FIG. 2 illustrates an embodiment of body armor which effectively spread the kinetic energy laterally so that the underlying tissues sustain far lower damage. As illustrated in FIG. 2, the body armor includes a layer 20 of a projectile impermeable material, such as Kelvar™, and an energy transfer layer 100, positioned between the projectile impermeable material layer 20 and the underlying tissue. When a projectile 10 encounters the projectile impermeable material layer 20, the projectile 10 transfers its kinetic energy to the projectile impermeable material layer 20.

Thereafter, the projectile impermeable material layer 20 transfers its kinetic energy to the energy transfer layer 100. The energy transfer layer 100, as will be explained in more detail below, spreads the energy laterally, the transfer of kinetic energy is transferred to the underlying tissue in the form of shock waves 300. These shock waves 300 contain less energy because the initial amount of kinetic energy has been spread, by the energy transfer layer 100, over a greater area than the area of initial impact. In other words, the energy transfer layer 100 effectively stops, reduces, and/or mitigates the transfer of kinetic energy from a ballistic projectile directly to the tissue so as to prevent, reduce, and/or mitigate damage to the underlying tissue and to enable the individual to recover more quickly.

FIG. 3 illustrates an embodiment of body armor which effectively spread the kinetic energy laterally so that the underlying tissues sustain far lower damage. As illustrated in FIG. 3, the body armor includes a layer 20 of a projectile impermeable material, such as Kelvar™, and an energy transfer layer 100, positioned between the projectile impermeable material layer 20 and the underlying tissue. The energy transfer layer 100 includes a shock stiffening layer 150 and a first high density foam layer 175, the first high density foam layer 175 being positioned between the shock stiffening layer 150 and the tissue. Optionally, a second high density foam layer 125 can be positioned between the projectile impermeable material layer 20 and the shock stiffening layer 150.

When a projectile 10 encounters the projectile impermeable material layer 20, the projectile 10 transfers its kinetic energy to the projectile impermeable material layer 20. Thereafter, the projectile impermeable material layer 20 transfers its kinetic energy to the energy transfer layer 100. The energy transfer layer 100 spreads the energy laterally 3000, the transfer of kinetic energy is transferred to the underlying tissue in the form of shock waves 4000. These shock waves 4000 contain less energy because the initial amount of kinetic energy has been spread (3000), by the energy transfer layer 100, over a greater area than the area of initial impact. In other words, the energy transfer layer 100 effectively stops, reduces, and/or mitigates the transfer of kinetic energy from a ballistic projectile directly to the tissue so as to prevent, reduce, and/or mitigate damage to the underlying tissue and to enable the individual to recover more quickly.

Referring again to FIG. 2, when the projectile 10 impacts the projectile impermeable material layer 20, projectile impermeable material layer 20 prevents projectile penetration, as in conventional body armor designs. However, as the projectile impermeable material layer 20 distorts, the resulting shock wave that would otherwise create tissue damage hits the pre-impact state flexible energy transfer layer 100.

In one embodiment, the resulting shock wave hits the pre-impact state flexible shock stiffening layer 150.

Optionally, if the embodiment includes second high density foam layer 125, the second high density foam layer 125 between the projectile impermeable material layer 20 and the shock stiffening layer 150 provides additional distance and time for projectile capture. Moreover, the second high density foam layer 125 can prevent penetration through the shock stiffening layer 150 because a projectile impermeable material layer backed up by a rigid layer could itself be penetrated in much the same way a punch press creates a hole in a metal plate.

The shock stiffening layer 150 is designed to become momentarily highly rigid, thereby spreading the area of effective tissue contact by as much as 100 times or more and effectively dissipating the energy in a non-lethal manner.

The shock stiffening layer 150 may have a construction as illustrated in FIGS. 4-6. More specifically, as illustrated in FIG. 4, the shock stiffening layer 150 includes two opposed shock stiffening sublayers 151 and 153. Each shock stiffening sublayer includes a plurality of shock stiffening sublayer elements 155. The shock stiffening sublayer elements 155 of shock stiffening sublayer 151 are interdigitated with the shock stiffening sublayer elements 155 of shock stiffening sublayer 153.

As illustrated in FIG. 5, the plurality of shock stiffening sublayer elements 155 may be straight-sided tapered interdigitated elements 157. On the other hand, as illustrated in FIG. 6, the plurality of shock stiffening sublayer elements 155 may be slightly convex interdigitated elements 159.

As noted above, the stiffness state of shock stiffening layer 150 is partial flexibility or conformability during manufacture, assembly, and/or general use. More specifically, as illustrated in FIG. 7, the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 153 and the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 151 are spaced with a gap S. The plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 153 and the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 151 have a width dimension of D. Thus, in a state of pre-impact, the total width of the shock stiffening layer 150, illustrated in FIG. 7, is 4(D)+3(S).

However, under the instantaneous influence of a shock wave, transfer of kinetic energy, created by projectile impact, the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 153 may become a momentarily fused with the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 151, as illustrated in FIG. 8. Assuming that the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 153 and the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 151 have a width dimension of D, the total width of the shock stiffening layer 150 at the time of impact, as illustrated in FIG. 8, is 4(D).

Moreover, under the instantaneous influence of a shock wave, transfer of kinetic energy, created by projectile impact, the plurality of shock stiffening sublayer elements 1530 of the shock stiffening sublayer 153 may become a permanently fused with the plurality of shock stiffening sublayer elements 1510 of the shock stiffening sublayer 151, as illustrated in FIG. 9. Assuming that the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 153 and the plurality of shock stiffening sublayer elements 155 of the shock stiffening sublayer 151 have a width dimension of D, the total width of the shock stiffening layer 150 at the time of impact, as illustrated in FIG. 9, is less than 4(D).

In the case of momentary fusing, as illustrated in FIG. 8, the shock stiffening sublayer elements 155 of the shock stiffening layer 150 become fused because the time involved in kinetic wave propagation is short. Moreover, the shock stiffening sublayer interdigitated elements 155 are compressed laterally before the shock stiffening sublayer elements' elastic response dictated by bulk elastic modulus permits the shock stiffening sublayer elements to react physically. The momentary (and highly increased) rigidity and inertia of the shock stiffening layer 150 serve to both reduce the speed and amplitude of the shock wave and spread the shock wave over a much larger body area.

For relatively lower projectile energy levels, the shock stiffening sublayer interdigitated elements 155 of the shock stiffening layer 150 may return to a pre-impact state or shape of flexibility. However, for higher kinetic energy levels, the surface interaction between the shock stiffening sublayer elements 155 of the shock stiffening layer 150 may cause the shock stiffening sublayer interdigitated elements 155 of the shock stiffening layer 150 to thermally bond or “weld’ together, as illustrated in FIG. 9.

Notwithstanding the state of fusion, the shock stiffening sublayer interdigitated elements 155 of the shock stiffening layer 150 effectively stop, reduce, and/or mitigate the transfer of kinetic energy from a ballistic projectile directly to the tissue.

As noted above, FIG. 4 illustrates two opposed shock stiffening sublayers 151 and 153 of the shock stiffening layer 150 spread apart prior to assembly. FIG. 5 illustrates the two opposed shock stiffening sublayers 151 and 153 assembled as a complete shock stiffening layer 150, wherein the plurality of shock stiffening sublayer interdigitated elements 155 are straight-sided tapered interdigitated elements 157. FIG. 6 illustrates the two opposed shock stiffening sublayers 151 and 153 assembled as a complete shock stiffening layer 150, wherein the plurality of shock stiffening sublayer interdigitated elements 155 are slightly convex interdigitated elements 159.

In FIGS. 4 and 5, the thickness of the planar backing portion of the shock stiffening sublayer 151 is depicted by t and the total thickness of the two interleaved shock stiffening sublayers 151 and 153, in combination, is depicted by T. In one embodiment, the thickness conversion factor, TCF=T/t, proportional to the cube root of the ratio of the moduli of the shock stiffening layer in the two states (pre-impact—FIG. 4 & impact—FIGS. 5 and 6), may be as small as 5 or less. In another embodiment, the thickness conversion factor, TCF=T/t, may be as large as 20 or more. The thickness conversion factor, TCF=T/t, should be optimized as a function of the tensile strength, bulk modulus, and other characteristics of the material chosen to create the shock stiffening sublayers 151 and 153.

As noted above, the bending resistance of a beam or plate is a cubic function of the beam's or plate's thickness. With respect to the shock stiffening layer, propagation of a kinetic shockwave depends on the shock stiffening layer either flexing inward, or displacing inward, or both.

It is further noted that instant conversion from partially flexible to highly rigid will cause a displacement rather than flexing on the part of the shock stiffening layer.

It is well known that under the application of shear forces at high speed, metals and other materials undergo brittle failure. Specifically, in a manufacturing environment, the forces resulting from a punch and die applying shear force rapidly and transversely to the surface of a metal sheet cause partial deformation of the metal through a small fraction of its thickness, followed by brittle failure through the remaining majority of its thickness. This is often referred to as the “punch press” effect and is exhibited by a wide range of materials. The punch press effect may also result from application of forces by a projectile against a metal plate, even with no corresponding die, because the extremely high speed and focused forces result in the parent material of the plate acting as its own die. High velocity ballistic impact of military ammunition can create a “punch press” hole in a metal sheet having a thickness corresponding to the diameter of the projectile, or even thicker.

The combination of a projectile impermeable material layer, high density foam layers, and transitionally flexible shock stiffening layer serves to prevent such a brittle-failure mechanism. The shock stiffening layer resists penetration in a manner that is superior to a solid layer of identical material and thickness because as the shock stiffening layer interacts with the impact energy of the projectile, the stiffness of the shock stiffening layer increases, thus allowing the energy to be spread laterally.

For example, when the thickness conversion factor, TCF=T/t, is 5.0, the ratio of shock stiffening layer's stiffness (during shock wave propagation through the shock stiffening layer) to the shock stiffening layer's stiffness immediately beforehand is T³/2(t³), which in this case is (5t)³/2t³, or ˜62. For a thickness conversion factor, TCF=T/t, of 20, the ratio of shock stiffening layer's stiffness (during shock wave propagation through the shock stiffening layer) to the shock stiffening layer's stiffness immediately beforehand is (20t)³/2t³, or 4000.

Thus, the shock stiffening layer can transition from a relatively flexible backing plate to a totally rigid plate at an extremely high speed. The speed of transition is fast enough to cause reduction and spreading of the shock wave, but slow enough to prevent the “punch press” effect.

As part of the transition from a relatively flexible backing plate to a totally rigid plate, the shock stiffening sublayer interdigitated elements 155 of interior shock stiffening sublayer 151 and exterior shock stiffening sublayer 153 generate significant heat as the shock stiffening sublayer interdigitated elements 155 slide together. Thus, upon sufficient impact, the shock stiffening sublayer interdigitated elements 155 will weld together in the area immediately around the projectile's impact.

The heat for the fusing of the shock stiffening sublayer interdigitated elements 155 dissipates a substantial portion of the energy associated with the projectile impact.

The first high density foam layer 175 beneath the shock stiffening layer 150 serves to provide room for a modest degree of deformation (flexing and displacement) of the shock stiffening layer 150 prior to tissue contact. In other words, the first high density foam layer 175 provides enough time for the shock stiffening layer 150 to (a) absorb a significant portion of the kinetic energy and convert it to heat, (b) slow the speed of the pressure wave impinging on underlying tissue, and (c) spread the effective area of tissue impact to an area as much as 100 times larger that for body armor constructed of a projectile impermeable material layer alone.

Materials such as titanium and other high strength metals are appropriate for use as the shock stiffening layer, but other materials including ceramics or composites are also appropriate; specific dimensions of the shock stiffening layer should be optimized to match the materials' properties.

It is noted that the shock stiffening layer and foam layers may be utilized over the entire area of the body armor or may be restricted to critical areas (e.g. over the heart) that are especially sensitive to blunt trauma.

It is further noted that the shock stiffening layer concept may be applied to different forms of armor, such as vehicle armor.

While various examples and embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that the spirit and scope of the present invention are not limited to the specific description and drawings herein, but extend to various modifications and changes.

Claims

1. A vesture comprising: a projectile impermeable material layer; andan energy transfer layer positioned between said projectile impermeable material layer and a region of tissue to be protected;said energy transfer layer spreading kinetic energy from a projectile impacting said projectile impermeable material layer substantially parallel to the region of tissue to be protected.

2. The vesture as claimed in claim 1, wherein said energy transfer layer is comprised of titanium.

3. The vesture as claimed in claim 1, wherein said energy transfer layer has a thickness conversion factor of about 5.

4. The vesture as claimed in claim 1, wherein said energy transfer layer has a thickness conversion factor of about 20.

5. A vesture comprising: a projectile impermeable material layer;a shock stiffening layer having opposed shock stiffening sublayers, each shock stiffening sublayer having a plurality of shock stiffening sublayer elements, said plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers being interdigitated; anda foam layer;said shock stiffening layer being positioned between said foam layer and said projectile impermeable material layer.

6. The vesture as claimed in claim 5, wherein said plurality of shock stiffening sublayer elements are tapered with straight sides.

7. The vesture as claimed in claim 5, wherein said plurality of shock stiffening sublayer elements are substantially convex shaped.

8. The vesture as claimed in claim 5, wherein said shock stiffening layer is comprised of titanium.

9. The vesture as claimed in claim 5, wherein said plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers momentarily fuse in response to a projectile impact with said projectile impermeable material layer.

10. The vesture as claimed in claim 5, wherein said plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers permanently fuse in response to a projectile impacting said projectile impermeable material layer.

11. The vesture as claimed in claim 5, further comprising a projectile impermeable material foam layer located between said projectile impermeable material layer and said shock stiffening layer.

12. The vesture as claimed in claim 5, wherein said shock stiffening layer is relatively flexible before a projectile impacts said projectile impermeable material layer and becomes relatively rigid in response to a projectile impacting said projectile impermeable material layer.

13. The vesture as claimed in claim 5, wherein said shock stiffening layer absorbs a portion of the kinetic energy from a projectile impacting said projectile impermeable material layer.

14. The vesture as claimed in claim 5, wherein said shock stiffening layer converts a portion of the kinetic energy from a projectile impacting said projectile impermeable material layer to heat.

15. The vesture as claimed in claim 13, wherein said shock stiffening layer converts a portion of the kinetic energy from a projectile impacting said projectile impermeable material layer to heat.

16. The vesture as claimed in claim 5, wherein said shock stiffening layer slows a speed of a pressure wave, created by a projectile impacting said projectile impermeable material layer, impinging on underlying tissue.

17. Armor comprising: a projectile impermeable material layer; andan energy transfer layer positioned between said projectile impermeable material layer and a region to be protected;said energy transfer layer spreading kinetic energy from a projectile impacting said projectile impermeable material layer substantially parallel to the region to be protected.

18. The armor as claimed in claim 17, wherein said energy transfer layer is comprised of titanium.

19. The armor as claimed in claim 17, wherein said energy transfer layer has a thickness conversion factor of about 5.

20. The armor as claimed in claim 17, wherein said energy transfer layer has a thickness conversion factor of about 20.

21. The armor as claimed in claim 17, wherein said region to be protected is a region of a vehicle.

22. The armor as claimed in claim 17, wherein said region to be protected is equipment.

23. Armor comprising: a projectile impermeable material layer;a shock stiffening layer having opposed shock stiffening sublayers, each shock stiffening sublayer having a plurality of shock stiffening sublayer elements, said plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers being interdigitated; anda foam layer;said shock stiffening layer being positioned between said foam layer and said projectile impermeable material layer.

24. The armor as claimed in claim 23, wherein said plurality of shock stiffening sublayer elements are tapered with straight sides.

25. The armor as claimed in claim 23, wherein said plurality of shock stiffening sublayer elements are substantially convex shaped.

26. The armor as claimed in claim 23, wherein said shock stiffening layer is comprised of titanium.

27. The armor as claimed in claim 23, wherein said plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers momentarily fuse in response to a projectile impact with said projectile impermeable material layer.

28. The armor as claimed in claim 23, wherein said plurality of shock stiffening sublayer elements of opposed shock stiffening sublayers permanently fuse in response to a projectile impacting said projectile impermeable material layer.

29. The armor as claimed in claim 23, further comprising a projectile impermeable material foam layer located between said projectile impermeable material layer and said shock stiffening layer.

30. The armor as claimed in claim 23, wherein said shock stiffening layer is relatively flexible before a projectile impacts said projectile impermeable material layer and becomes relatively rigid in response to a projectile impacting said projectile impermeable material layer.

31. The armor as claimed in claim 23, wherein said shock stiffening layer absorbs a portion of the kinetic energy from a projectile impacting said projectile impermeable material layer.

32. The armor as claimed in claim 23, wherein said shock stiffening layer converts a portion of the kinetic energy from a projectile impacting said projectile impermeable material layer to heat.

33. The armor as claimed in claim 31, wherein said shock stiffening layer converts a portion of the kinetic energy from a projectile impacting said projectile impermeable material layer to heat.

34. The armor as claimed in claim 23, wherein said shock stiffening layer slows a speed of a pressure wave, created by a projectile impacting said projectile impermeable material layer, impinging on an underlying region to be protected.

35. The armor as claimed in claim 34, wherein said underlying region to be protected is a region of a vehicle.

36. The armor as claimed in claim 34, wherein said underlying region to be protected is equipment.