COMPOSITE ARMOR WITH A CELLULAR STRUCTURE
A composite armor 10 is provided with a cellular structure 12 having a plurality of composite inserts 14 arranged in openings 20 provided in the cellular structure 12. A pair of laminate sheets are arranged on oppositely facing sides of the cellular structure 12 and covering the inserts 14. The laminate sheets 26 and 28 are bonded to the structure 12 and the inserts 14 by an adhesive. The cellular structure 12 includes a plurality of fibers extending continuously throughout the cellular structure 12.
This invention was made with Government support under Agreement No. W911NF-04-2-0032 awarded by ARL. The Government has certain rights in the invention.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates generally to armor used for preventing the penetration of structures by projectiles. More specifically, the invention relates to an improved armor including a fiber grid having composite tiles retained in the grid that together provide overall support to the structure being protected while also improving the armor performance of each individual composite tile.
2. Background of the Invention
Armor systems have been known to include thick metal as a skin of a structure being protected. For example, military vehicles have, for several years, included a thick metal plate on their exterior in order to reduce the likelihood of projectile penetration. Such thick metal armor systems while effective can also be extremely heavy and, as such, cause problems relating to vehicle speed, fuel consumption and vehicle assembly.
In some cases, these metal armor systems have been replaced with lighter weight armor systems made from composite materials having reinforced fibers made of, for example, Kevlar, S-2 glass, graphite, or high molecular weight polyethylene. Such armor systems have utilized these multiple layers of composite materials in order to achieve reduced overall weight, and provide sufficient structural properties, while preserving the ability of the armor to provide protection against penetration. For example, some known systems include the use of Kevlar in combination with two outer plates surrounding such Kevlar. Illustrative of such a composite armor system is disclosed in U.S. Pat. No. 4,186,648.
Also, armor systems using ceramic plates in connection with a grid are well known in the art as capable of providing protection against penetrating high speed projectiles while providing a reduction in the overall weight of the armor system. The ceramic plates have been known to have convex surfaces. U.S. Pat. No. 6,826,996 discloses convex plates inserted into a honeycomb grid. Upon impact by a projectile into such ceramic plates, it has been known that managing the propagation of cracks from the impacted plate to an adjacent plate is critical.
The prior art grids are made of steel, fiber, or composite materials and are used in connection with holding ceramic plates inserted into openings formed by such grid structures. For example, U.S. Pat. No. 5,456,156 discloses a grid structure made of metal strips. The openings have been known to be either blind openings, opening only to one side of the grid, or, through holes, open to both sides of the grid. The openings of such grids have been shaped in many different forms including, for example, squares, triangles, and hexagons. The grid structure is usually designed with a material having an effective acoustic impedance lower than the ceramic plates in order to reduce the propagation of damaging stresses to adjacent ceramic plates.
In order to manage the propagation of such stresses, prior art armor systems have used auxiliary layers of laminate sheet material bonded to the front and the back of the grid structures. In some cases, only one laminate sheet has been bonded to either one of the front or the back of such grid structures. It has been known to make such laminate sheet material out of Kevlar. For example, U.S. Pat. No. 5,349,893 discloses a composite laminate sheet made of woven fiber in a resinous matrix. Such laminate sheet materials can be bonded to the grid structure with resins.
Illustrative of the prior art is U.S. Pat. No. 6,826,996 assigned to General Dynamics Land Systems, Inc. and Mofet Etzion Agricultural Cooperative Association Ltd. The '996 patent discloses a honeycomb grid structure having openings for receiving convex composite plates and a pair of preform sheets secured to both sides of the grid structure. The '996 patent discloses the honeycomb grid as made of material selected from the group consisting of stainless steel, aluminum, aramid sheet, fiber, or fabric.
Testing of such known armor systems having grid structures with composite inserts surrounded by preform sheets has revealed that the propagation of cracks and debris, created during impact, weakens the adjacent composite plates. The propagation of such cracks results from poorly designed grid structures failing to eliminate both crack propagation, debris, and stress wave propagation.
SUMMARY OF THE INVENTIONIt is an object of the present invention to provide a composite armor that will prevent the penetration of projectiles in a structure while also providing structural support to the same structure.
More specifically, an object of the invention is to provide a composite armor having a one-piece integrally formed composite cellular structure for retaining composite inserts, which in combination with resins and laminates, prevents projectiles from penetrating a structure.
Another object of the present invention is to provide a uniform one-piece composite cellular structure made of continuous fibers providing high tensile strength in order to radially confine composite inserts used in connection with such grid.
Further scope and applicability of the present invention will become apparent from the following detailed description, claims and drawings. However, it should be understood that the specific examples in the detailed description are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.
The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which:
Referring now to the drawings, an armor system is shown in general at 10 in
The armor system 10 further includes a pair of laminates 26 and 28 secured to the cellular structure 12 and the composite inserts 14. The laminates 26, 28 are secured with the use of a bonding material such as a resin which may also be used as a filler applied on the inserts 14 and, in some cases, around at least a portion of the perimeter portion 25.
Similar to
The cellular structure 12, as shown in
The present invention 10 is generally shown at 100 in
The present invention 10 is assembled according to the following steps. The cellular structure 12 is provided on a fixture used for holding the structure. The inserts 14 are inserted into the openings 20 of the structure 12 and a filler is applied to the inserts 14 including around at least a portion of the perimeter 25 of the inserts 14. At least one of the laminate sheets 26, 28 are applied over the structure 12 having the inserts 14 contained in the openings 20. A bonding resin is applied to the entire structure 12, having the inserts 14 in the openings 20 along with the filler and the laminate sheets, thereby created an assembly which is infused together. In the preferred embodiment, the infusing is achieved through the use of a known process referred to as Vacuum Assisted Resin Transfer Molding (VARTM). Although the VARTM infusion process is preferred, it should be appreciated that other methods of infusion may also be used.
The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.
Claims
1. A composite armor comprising:
- an integrally formed cellular structure having oppositely facing sides and a plurality of openings on at least one of said oppositely facing sides;
- a plurality of composite inserts received by said plurality of openings;
- a laminate sheet secured to at least one of the oppositely facing sides of the cellular structure to provide structural reinforcement and contain debris after impact; and
- wherein the integrally formed cellular structure includes continuously extending fibers, and wherein said continuously extending fibers continuously extend throughout said cellular structure.
2. The composite armor as claimed in claim 1, wherein said laminate sheet has an acoustic impedance of between 0.7×106 and 40×106 kg/m2 as measured in a direction parallel to a normal of the laminate sheet.
3. The composite armor as claimed in claim 2, wherein said laminate sheet includes at least two different materials on each of said oppositely facing sides of said cellular structure.
4. The composite armor as claimed in claim 1, wherein said fibers are made of a high modulus strength material selected from the group consisting of glass, carbon, and aramid.
5. (canceled)
6. The composite armor as claimed in claim 1, wherein said composite insert includes first and second surfaces which are substantially perpendicular to an axis A of said opening.
7. The composite armor as claimed in claim 1, wherein said opening extends between both of said oppositely facing sides.
8. The composite armor as claimed in claim 1, wherein said composite insert includes a plurality of inserts spaced a predetermined distance from each other.
9. The composite armor as claimed in claim 6, wherein said first and second surfaces include a minimum modulus of 2.0×1010 N/m2 measured in a through thickness orientation.
10. The composite armor as claimed in claim 1, wherein said cellular structure includes an exterior wall portion and an interior wall portion.
11. The composite armor as claimed in claim 10, wherein said exterior wall portion and said interior wall portion have varying widths.
12. The composite armor as claimed in claim 1, wherein a filler is received in said opening of the cellular structure and adjacent to at least a portion of said composite insert.
13. The composite armor as claimed in claim 1, wherein at least one cellular structure is fixedly attached and made integral with a structure.
14. A method of making a composite armor, comprising the steps of:
- providing an integrally formed cellular structure having at least one opening and being made of a plurality of continuous fibers, said continuous fibers extending continuously throughout the cellular structure without any break in said fibers;
- inserting at least one composite insert into said at least one opening;
- applying a filler onto said composite insert and about at least a portion of a perimeter of said insert;
- applying at least one laminate over said cellular structure including said at least one composite insert and said filler;
- applying a resin on said laminate; and
- infusing said resin to thereby cause said laminate, said filler, said insert and said cellular structure to bond forming a composite armor.
15. The method of making a composite armor as claimed in claim 14, wherein said at least one laminate has an acoustic impedance of between 0.7×106 and 40×106 kg/m2 as measured in a direction parallel to the normal of the laminate sheets.
16. A composite armor comprising:
- an integrally formed cellular structure having oppositely facing sides and a plurality of openings on at least one of said oppositely facing sides, wherein said cellular structure is formed from continuous fibers, and wherein said continuous fibers substantially extend continuously throughout said cellular structure without any break in said fibers;
- at least one composite insert received by said plurality of openings; and
- a laminate sheet secured to at least one of the oppositely facing sides of the cellular structure to provide structural reinforcement and contain debris after impact.
17. A composite armor comprising:
- an integrally formed cellular structure having outer walls and inner walls having oppositely facing sides and a plurality of openings on at least one of said oppositely facing sides;
- at least one composite insert received by said plurality of openings;
- a laminate sheet secured to at least one of the oppositely facing sides of the cellular structure to provide structural reinforcement and contain debris after impact; and
- wherein at least one of the inner walls and outer walls includes a plurality continuously extending carbon fiber reinforced polymer fibers and wherein said fibers extend without any break in said fibers.
18. (canceled)
19. (canceled)
20. The composite armor as claimed in claim 17, wherein said fibers only extend continuously throughout the outer walls.
21. The composite armor as claimed in claim 17, wherein said fibers extend continuously throughout only the inner walls.
22. The composite armor as claimed in claim 17, wherein said fibers continuously extend throughout both said outer walls and said inner walls.
23. The composite armor as claimed in claim 17, wherein said fibers continuously extend throughout said outer walls and a plurality of separate fibers extend continuously throughout said inner walls.
24. The composite armor as claimed in claim 23, wherein said inner and outer walls are formed together as a single integrally formed cellular structure.
25. The composite armor as claimed in claim 17, wherein said fibers include individual fibers extending continuously throughout said cellular structure.
26. The composite armor as claimed in claim 1, wherein said fibers include individual fibers extending continuously throughout said cellular structure.
27. The composite armor as claimed in claim 14, wherein said fibers include individual fibers extending continuously throughout said cellular structure.
28. The composite armor as claimed in claim 16, wherein said fibers include individual fibers extending continuously throughout said cellular structure.
29. (canceled)
30. The composite armor as claimed in claim 14, wherein said fibers extend continuously in one of a clockwise or counter-clockwise orientation.
31. (canceled)
Type: Application
Filed: Aug 15, 2006
Publication Date: Apr 15, 2010
Inventors: Brian R. Scott (Middletown, DE), Nabil F. Grace (Rochester Hills, MI)
Application Number: 11/504,343
International Classification: F41H 5/04 (20060101); F41H 5/02 (20060101); B29C 65/00 (20060101);