US2723214A

US2723214A - Elastic cascading impact absorber

Info

Publication number: US2723214A
Application number: US306088A
Authority: US
Inventors: Earl A Meyer
Original assignee: Bjorksten Research Laboratories Inc
Current assignee: Bjorksten Research Laboratories Inc
Priority date: 1952-08-25
Filing date: 1952-08-25
Publication date: 1955-11-08
Anticipated expiration: 1972-11-08

Description

Nov. 8, 1955 E. A MEYER ELASTIC CASCADING IMPACT ABSORBER Filed Aug. 25, 1952 4 Sheets-Sheet l E YE R Mt /j A Harney IN VEN TOR.

EARL A BY /OJZ 1955 E. A. MEYER 2,723,214

ELASTIC CASCADING IMPACT ABSORBER Filed Aug. 25, 1952 4 Sheets-Sheet 2 F IG 5 FIG] INVENTOR.

gg fiix NOV. 8, 1955 E A, MEYER ELASTIC CASCADING IMPACT ABSORBER 4 Sheets-Sheet 4 Filed Aug. 25, 1952 INVENTOR.

EARL A. EYE I BY 4 Affamey titted 2,723,234 Patented Nov. 8, 1955 ice 2,723,214 ELASTIC cAscAniNo IMPACT Assonsm:

Earl A. Meyer, Madison, Wis, assignor to Bjorksten Research Laboratories, Inc., a corporation of Illinois Application August 25, 1952, Serial No. 3tl6,tl88 17 Claims. (Cl. 154-52.5)

wise so that it presents a large cross-section toward the armor.

It is obvious, of course, that armor should be as light as possible, it is desirable that the armor not depend for its operability upon the softness of the projectile; it

should not be subject to the limitation thatit will operate only if the projectile is soft enough to mash or squash sufiiciently. y

it is thcreforean object of this invention to provide an impact-absorbing armor, suitable for use by individual personnel, which is light in weight and yet will protect the wearer from being harmed by impinging projectiles.

Another object is such a device composed of a plurality of layers of rigid plates and elastic sheets.

Further objects will become apparent from the drawings and the following detailed description in which it is my intention clearly to set forth and describe my invention and to show its applicability without limiting its scope. In the drawings and description like reference numerals refer to like parts and: I

Figure l is a partiallycut away perspective view from above of a portion of the armor of my invention;

Figure 2 is a perspective view showing the armor upon an individual;

Figure 3 is a cross-sectional view of a portion of the armor in which its mode of operation when struck by bullets is shown; A

Figure 4 is aplan view showing the relationship of therigid plates in each of three layers of rigid plates in the embodiment according to-Figure 1; p

Figure 5 is a plan view showing the relationship of rigid plates in three layers in another embodiment;

Figure 6 is a plan view showing the interrelationship of rigid plates in three layers thereof in another embodiment;

Figure 7 is a plan view showing the interrelationshipof rigid plates in three layers thereof in another embodiment;

Figure 8 is a plan view showing the interrelationship of rigid plates in three layers thereof in another embodiment;

Figure 9 is aplan view showing the interrelationship of rigid plates in three layers thereof in another embodiment;

Figure 10 is a plan view showing the interrelationship of rigid plates in three layers thereof in another embodiment;

Figure 11 is a plan view showing the interrelationship of rigid plates in three layers thereof in another embodiment;

Figure 12 is a plan view showing the interrelationship of square rigid plates in twolayers thereof in another embodiment; and

Figure 13 is a plan view showing the interrelationship of rigid plates in four layers thereof in another embodiment.

Referring now to Figure I, there is shown a portion of armor consisting of three layers of rigid plates respectively 1, 3, and 5 and'laminated thereinbetween and attached thereto, three layers of elastic material respectively 2, 4, and 6. The layers may be attached to each other by means of adhesives or heat or by a combination of these methods or by other means known to the art. Layer 1 is composed of rigid plates such as plate 7 which has all of its edges in abutting relation to adjacent plates, and which may be composed of metal or of glassfabric reinforced plastic. The plates in layer 1 are preferably square as shown but may be certain other regular geometric shapes as described more fully hereinafter. The plates in layer 1 such as plate 7 must be small enouglnhard enough, and rigid enough so that when hit by a projectile each will not be pierced by the bullet but will move as a unit with the bullet. Therefore, the plates may suitably be about /2" in width to about 6" in width and may be from about .005" thickness to about 1" thickness. Plates of layer 1 may be adhesively welded or attached to layer 2 which is composed of elastic material such as rubber having a spring constant selected so that the plates of layer 1 will compress layer 2 when struck by a projectile, compressing,

- layer 2 and transmitting force to'layer 3 at the sametime slowing down the projectile and converting a certain portion of its energy from kinetic to potential energy stored in the compressed material. Below layer 2 and attached thereto is a layer 3 composed of square rigid plates such as plate 8, with edges abutting those of adjacent plates. Each of the plates in layer 3 such as 8 has a surface area larger than that of each of the plates such as 7 in layer 1, and the plates of layer 3 are so arranged that the junctions at their edges or joints, such as joint9 between plate 8 and an adjoining plate, do not fall directly below any of the joints in layerl. By making the plates such as 8 have four times the area of the plates such as 7, where the plates are square, this may be accomplished with ease. The plates of layer 3 may be either thinner or thicker than those of layer 1 and may have a higher or lower springconstant. Since the force of the projectile is transmitted to these plates by the relatively large area of one or more of the plates such as 7, as compared with the relatively small area presented by the nose of a bullet, it is not so necessary that plates such as 8 be of a material which will resist puncture as it is desirable that they be of such a material that they will not be torn apart or so severely bent that they will fail to transmit force to the next layer below through almost the entire area on the lower surface of each plate. Layer 4 below. layer 3 is composed of an elastic material having a spring constant which may be difierent from that of layer 2; for example, it may beselected to deform less than layer 2 and convert and store more energy in so deforming. Below layer 4 and attached thereto is another layer of metal plates 5. Layer 5 is composed of rigid plates which may be square as shown, such as plate 10. If square plates are used, each of the plates such as it) preferably has a surface area four times greater than the plates such as 8 in the next layer 3 of plates above and the plates are so arranged that the joints thereinbetween such as 11 do not fall directly below and parallel to the joints in'layer 3 but as shown in a projection thereof by Figure 4, have merely an intersecting relationship as shown for example at 12. Below layer 5 is another layer 6 of elastic material attached to the plates of layer 5. Materials of

layer

5 and 6 are selected to have spring constants which will provide a maximum of energy conversion or storage with a minimum of deformation, and serve as the final protection for the wearer. It will, of course, be understood that the invention may be operable with either more layers or less layers than shown such as two layers of rigid plates and two layers of elastic material or four or five layers each of rigid plates and elastic material, except that two layers of each is the minimum with which the invention is operable.

Referring now to Figure 3 there is shown the manner in which the structure operates to absorb the energy of a projectile striking the outer surface of the outermost layer of plates. This is illustrated for a structure embodying square plates such as those of the embodiment of Figure l but suitably illustrates the manner in which the invention operates with plates of other shapes. Fabric 13 which may cover the armor on both sides when worn by an individual is shown in Figure 2 but is not shown in Figure 3, since it is not critical in the operation of the invention. Bullet 14 is shown in shadow outline just prior to striking the plates of layer 1', and is shown at 14 an instant after striking these plates. The bullet has struck at the juncture of

plates

15 and 16. Since these do not overlie a joint in layer 3 nearly the whole of

plates

17 and 18 in layer 3' have been deflected, plate 17 being deflected a good deal more than plate 18 by the force transmitted to it from the

plates

15 and 16 by the elastic material of layer 2'. Similarly, since joint 19 between

plates

17 and 18 does not overlie joint 20 between

plates

21 and 22 in layer but instead overlies plate 22 itself, plate 22 is deflected by the energy transmitted to it by the elastic material of layer 4' and its deflection is restrained by layer 6' and also transmitted to the wearer by layer 6'. Thus the force transmitted to the wearer, being the residue of force which has not been absorbed in deflecting the various portions of the armor structure is transmitted to the wearer over a very large area, comparatively, by plate 22 acting through the material of layer 6".

Thus the force of the projectile is distributed over a large area by a series of cascading rigid plates of regularly increasing size, connected together by layers of elastic material of selected spring constants, and the area through which force is transmitted to the next adjacent layer of plates is increased by a regular factor such as four for each succeeding layer.

To minimize the impact on the wearer it is desirable that the process of absorbing the energy of the bullet be spread out over as long a duration as possible. This is accomplished by the elastic material such as shown in

layers

2, 4, 6, 2', 4' and 6'. The spring constants of these several layers maybe equal or may be varied at will but it is believed best that the outermost layer of elastic, such as layer 2, have the lowest spring constant in order that the relatively small rigid plates which come into direct contact with the projectile shall each move as a unit, since these plates must not be pierced by the bullet if the structure is to work efficiently. The spring constant of the elastic layer next below, such as layer 4, should generally be greater than that of layer 2 in order to absorb more energy, more effectively to delay the transmittal of that energy to the next adjacent layer below, and more efiiciently to distribute the energy of the bullet over the widest possible area in the next layer of plates below. Thus the layer of elastic next adjacent the wearer, such as layer 6, should generally have the highest spring constant of the several layers of elastic. By grading the spring constants in this manner, the material of the outermost layer of elastic, such as layer 2, may be almost completely compressed before the material of the next layer below such as

layers

4 and 6 becomes compressed appreciably. Thus the forward motion of the projectile is halted over a maximum length of time, the rate of energy absorption increasing as the energy is transmitted through the layers of the armor and as the energy remaining to be absorbed decreases.

layers of elastic material, the stored energy is immediate- 1y available for reconversion into kinetic energy. This reconversion begins at the moment the bullet ceases to tarvel forward, the bullet being accelerated in a reverse direction. Because a large proportion of the energy which the bullet had at the moment of striking is stored in the compressed elastic layers and because the conversion and storage is relative efficient, a large portion of the energy which the bullet has upon striking the armor may be returned to it and therefore it may be ejected outwardly from the armor with considerable force.

Bullet 23 is shown in shadow outline a moment before striking the outer surface of the armor and is shown as 23 an instant after striking the outermost layer of plates 1 and being deformed somewhat. Bullet 23 strikes the middle of plate 24 in layer 1' and pushes plate 24 straight downward causing the elastic material of layer 2 to transmit the force to plate 25 in layer 3 directly below and to convert and store a certain amount of energy by being compressed. Since the energy is transmitted directly to the center of plate 25, it also moves directly downward as a unit and transmits energy to plate 26 through the material of layer 4 which converts and stores energy by being compressed. Plate 26 also moves directly downward and thus transmits any remaining energy to the individual wearer over a relatively very large area through layer 6 which also stores and converts energy by being compressed.

Bullet 27 is shown in shadow outline a moment before striking the surface of the layer 1 and is shown an instant later as 27' striking plate 28 in layer 1' directly in the center with resultant deformation of bullet 27. Since plate 28 overlies a joint between

plates

29 and 30 in layer 3' below, instead of overlying the center of one of said plates, energy is transmitted to both of

plates

29 and 30 through layer 2' which itself converts and stores a certain amount of energy.

Plates

29 and 30 are both deflected somewhat and transmit energy to layer 4' which is compressed and thereby converts and stores energy and transmits some to substantially the whole of plate 31 in layer 5 below which in turn transmits energy to 6 which stores some and transmits the remaining energy to the wearer over a relatively large area.

Bullet 32 is shown in shadow outline a moment before striking the plates of layer 1' and is shown deformed as 32' a moment after striking plate 33 in layer 1'. Bullet 32 has neither struck plate 33 in the center nor has it directly struck the joint between

plates

33 and 34 in layer 1'. The energy of its impact is nevertheless transmitted respectively to

plates

35 and 36 in layers 3' and 5' just as in the other examples mentioned above, the energy being transmitted by the materials of layers 2' and 4' with concomitant energy conversion and storage just as in the other examples. That part of the energy which is not stored in the structure is transmitted to the wearer over a relatively large area through the material of layer 6 by the relatively large plate 36.

Referring now to Figure 4 wherein is shown a plan view illustrating the interrelationship of an armor structure according to the invention comprising three layers of square plates, the plates of the outermost layer of plates, which is the layer having therein the smallest plates are represented by solid lines. The plates in the layer next below, the second or middle layer, are represented by dotted lines, and the plates in the bottom or innermost layer, which would be nearest the wearer of such armor, are represented by dashed lines. It may be noted that each plate has a surface area four times greater than the area of a plate in the layer next above so that the area relationship for plates in the three layers shown is 1:4: 16, or 1:4 between any two succeeding layers.

Referring now to Figure 5 there is shown an embodiment in which the invention is applied to hexagonal plates, those in the outermost layer being represented by solid lines, those in the second layer being represented by dotted lines, and those in the third layer being represented by dashed lines. It will be noted that in this embodiment none of the joints between plates in any layer-fall directly above or below and parallel with joints in any adjacent layer, although some of the joints in the first layer are superimposed directly above and parallel with joints in the third layer, such as at 37. This seems to be a weak point in the armor since the joint indicated at 38 between plates in the second layer is very close to the jointsindicated at 37 in the first and third layers. Thus although the invention is workable with the arrangement of hexagonal plates shown in Figure 5, this embodiment is not as suitable as that of Figure 4 and of other embodiments shown in other figures. The surface area ratio of the plates in the outermost, middle and innermost layers of Figure 5 is 1:4:16 and therefore the surface area ratio between the plates of any two adjacent layers is 1:4.

In Figure 6 there is shown another embodiment comprising hexagonally shaped plates. In this embodiment also the plates of the outermost layer are represented by solid lines, those of the layer next below by dotted lines, and those of the lowest or innermost layer by dashed lines. In this embodiment none of the joints between plates in any layer is superimposed above and parallel with any joint between plates in any other layer and points such as 39 and 4! where the point of intersection of three plates in the first layer is almost above the point of intersection of three plates in the third layer are close to the center of plates in the second layer so that such areas are not points of great weakness. Similarly points such as 41 where a joint in the first layer is superimposed almost if not altogether directly above and parallel with a joint in the third layer are located in such places that at least two plates in the second layer will be materially ait'ected by a bullet striking at such point so that although points such as 41 may probably be described as the weakest point in the armor of this embodiment, they are nevertheless not so weak as to make the armor unworkable. The area ratio of plates in the outermost, middle'and innermost layers of the embodiment of Figure 6 is approximately 113.2: and therefore the area ratio between plates in any two adjacent layers is approximately 1:32.

Referring now to Figure 7, there is shown an embodiment in which the shape of the plates in each of the three layers shown is identical but is not a polygon. The plates of this embodiment may generally be described as crescent shaped but are actually formed of two parallel straight lines forming two sides, said sides being connected by two arcuate sides formed by parallel arcs of the same radius. The radius of said arcs might suitably be greater or less those in the layer next below by dotted lines and those in the innermost layer shown in Figure 7 are represented by dashed lines. More layers of course might be used. Each plate has two corners such as 42 and 42' of plate 43 which are formed by said arcuate sides intersecting said straight sides at an acute angle and two corners such as 44 and 44' where said sides join at an obtuse angle. The plates in each layer may be so arranged that in adjacent layers the acutely angular corners point in opposite directions as shown in Figure 7. Thus the acutely angular corners of the plates in the outermost layer such as corners 42 and 42' point toward the bottom of the figure and the acutely angular corners such as 4.5 and 45' of plate 46 in the next layer point toward the top of the figure. At no point are joints in any one layer superimposed above and parallel with joints in the next adjacent layer. The surface area ratio of the plates in the three layers is 1:4:16 and therefore the surface area ratio between the plates in any two adjacent layers is 1:4. This ratio might quite suitably be either larger or smaller and the acutely angular corners of plates in each layer might all point in the same direction.

In Figure 8 there is shown an embodiment in which the plates in each layer have a rectangular shape. As in than that shown in Figure 7. The. plates in the outermost area are represented by solid lines,

because neither the center of a plate nor an between six triangular plates falls above the center of the other figures, solid lines outline the plates in the I first or outermost layer, dotted lines outline the plates in the middle layer and dashed lines outline the plates in the lowest or innermost layer. None of the joints between plates in any layer are superimposed above and parallel with joints in any other layer. This embodiment may suitably be employed in place of such a structure as that of Figure 4. Because the plates are rectangular and therefore there are many more joints in one direction than in the other the structure is more flexible in one direction than in the other. The area ratio of the plates in the three layers of this embodiment is 1:4:16 and therefore the area ratio between plates in any two adjacent layers 'is 1:4.

Referring now to Figure 9 wherein is shown an embodiment similar to that of Figure 8 but comprising plates which in every layer have the shape of parallelograms, the plates of the outermost layer are shown by solid lines and those of the next two layers below are shown respectively by dotted lines and dashed lines. In this embodiment also none of the joints between plates in any layer are superimposed above and parallel with joints in any other layer and the structure of this embodiment may suitably be used where it is desired that the armor be flexible in two directions but that it be more flexible in one of these two directions and that the two directions of flexibility should hear an acutely angular relationship to each other.

Referring now to Figures 10 and 11 there is shown therein two embodiments embracing plates which have the shape of triangles. In the embodiment of Figure 10 there is no joint between plates in one layer which is superimposed above and parallel with any joint between plates in any other layer. In both embodiments the plates of the outermost layer are shown by solid lines and those of the next two layers of plates below are respectively shown by dotted lines and dashed lines. The area ratio of plates in the three layers of each of thetwo embodiments is 1:4:16 and therefore the area ratio between plates of any two adjacent layers is, of course, 1:4

The arrangement of the plates and the layers of Figure 11 is symmetrical since every plate in either the innermost layer or the middle layer has directly superimposed above its center either an intersection between six triangular plates in the layer next above or the center of a plate in the layer next above. However, at certain points such as 47 and 47, joints between plates in the outermost layer are superimposed above and parallel with joints between plates in the innermost layer. The plates in the layers of Figure 10 are not arranged symmetrically but nowhere does a joint between plates fall directly above and parallel with any other joint between plates. The structure of Figure 10 is considered not symmetrical intersection any plate in any layer below.

Referring now to Figure 12, there is shown therein an armor comprising only two layers of rigid plates, these plates having the shape of squares. The outermost layer of plates is shown by solid lines and the inner layer is shown by dotted lines. surface area of plates in the two layers is 1:9.

In Figure 13 there is shown an embodiment similar to that of Figure 9' in that the plates have the shape of parallelograms. .Four layers of plates are shown, the

plates of the outermost layer being indicated by solidlines, those of the layer next below by dotted lines, those of the third layer by dashed lines, layer by dot-dash lines.

joint between any other two plates in any layer. The

shaped plates, such as the angle of corner 48 of plate 49 The ratio between the andthose of the fourth No joint between any two plates is superimposed directly above and parallel with any in the outermost layer. The ratio of the surface areas of plates in the four layers is 1:2:428, and therefore the ratio between the surface areas of plates in any pair of adjacent layers is 1:2.

The rigid plates of the invention may be made of any one of a large group of materials. Laminates of glass fabric impregnated with polyester resins and glass fiber filled polyester and urea formaldehyde and melamine formaldehyde resins have been found particularly suitable but preferable materials include any thermosetting synthetic resin such as polyester resins and urea-melamineand phenol-formaldehyde resins filled or otherwise reinforced with glass fibers in either mat or fabric form or with other fibrous materials such as canvas. Other materials are also suitable such as, for example, any one of a number of hard armor plate alloys. A lighter armor is achieved with the preferred resinous materials but such hard alloys which may be used include alloys comprising cobalt, chromium and tungsten (sold as Stellites) alloys such as nickel, cobalt, manganese and chromium-steels comprising a relatively large percentage of iron, or an alloy of 60% nickel, 20% chromium, 10% iron, 1.75% manganese and .5% carbon sold as fire armor.

The material for the elastic layers which intervene between the layers of rigid plates may be selected from a wide group of elastomers, it being required merely that the material act in a manner comparable to a layer composed of a multitude of small coil springs having their axes parallel one to another and normal to the surface of said layer. Sponge rubber has been found suitable. The elastic may comprise acrylates such as substituted and unsubstituted polyethyl and methyl methacrylates and polyethyl and methyl acrylates, cellulose resins such as alkyl cellulose, cellulose acetate, cellulose butyrate, and mixed cellulose esters, vinyl resins such as polyvinyl chloride, polyvinylidine chloride, and thereof, and such as polyvinyl acetals, particularly polyvinyl butyral, which may be modified by cross-linking agents, styrenes such as substituted and unsubstituted polystyrene, rubber compounds, such as natural rubber, GR-S, GR-N, and chlorinated rubber, polyisobutylene, neoprene, polyesters, polysulfones, nylons, silicones, and polyfluorinated hydrocarbons, and polyethylene.

It will thus be seen that the invention is broad in scope.

Having thus disclosed my invention, I claim:

1. Armor adapted to restrain penetration of projectiles therethrough, comprising layers of rigid plates having laminated thereinbetween layers of elastic material, and means for holding said elements together, each of said layers of rigid plates comprising plates having edges abutting.

2. Armor adapted to restrain penetration of projectiles therethrough, comprising layers of rigid plates having laminated thereinbetween layers of elastic material, and means for holding said elements together, each of said layers of rigid plates comprising plates having edges abutting, each of the plates in each of said layers of rigid plates having an area greater than the area of each of the plates in the next above layer of rigid plates.

3. Armor adapted to restrain penetration of projectiles therethrough, comprising layers of rigid plates having laminated thereinbetween layers of elastic material, and means for holding said elements together, each of said layers of rigid plates comprising plates having edges abutting, each of the plates in each of said layers of rigid plates having an area greater than the area of each of the plates in the next above layer of rigid plates and the plates in each layer being so arranged that no joint between any two plates is superimposed directly above and parallel with any joint in any next adjacent layer of rigid plates.

4. Armor adapted to restrain penetration of projectiles therethrough and adapted to be worn by individuals, comprising layers of rigid plates having laminated thereinbetween layers of elastic material, and means for holdco-polymers ing said elements together, each of said layers of rigid plates comprising plates having edges abutting, each of the plates in each of said layers of rigid plates having an area at least two times as great as the area of each of the plates in the next above layer of rigid plates and the plates in each layer being so arranged that no joint between any two plates is superimposed directly above and parallel with any joint in any next adjacent layer of rigid plates.

5. The armor of claim 4 in which each of said rigid plates is quadrilateral in shape.

6. The armor of claim 4 in which each of said rigid plates is triangular in shape.

7. The armor of claim 4 in which each of said rigid plates is hexagonal in shape.

8. The armor of claim 4 in which the area relationship between each of the plates in one of said layers of rigid plates and each of the plates in the next adjacent said layer of rigid plates is 1:4.

9. The armor of claim 4 in which the area relation ship between each of the plates in one of said layers of rigid plates and each of the plates in the next adjacent said layer of rigid plates is substantially 1:3.2.

10. Armor adapted to restrain penetration of projectiles therethrough and adapted to be worn by individuals, comprising layers of rigid plates having laminated thereinbetween layers of elastic material, and means for holding said elements together, each of said layers of rigid plates comprising plates of identical shape having edges abutting, each of the plates in each of said layers of rigid plates having an area at least two times as great as the area of each of the plates in the next above layer of rigid plates and the plates in each layer being so arranged that no joint between any two plates is superimposed directly above and parallel with any joint in any next adjacent layer of rigid plates.

11. Armor adapted to restrain penetration of projectiles therethrough comprising a layer of rigid plates, a layer of elastic material next adjacent below attached thereto, a second layer of rigid plates below and attached to said elastic layer, each of the plates of said layer having an area at least two times greater than the area of each of the plates in the first layer and so arranged that none of the joints between plates in the second layer are directly below and parallel with any joint between plates in the first layer, and a second layer of elastic material below said second layer of plates attached thereto, and means for holding said elements together.

12. The armor of claim 11 in which all of said rigid plates are quadrilateral in shape.

13. The armor of claim 11 in which all of said rigid plates are triangular in shape.

14. The armor of claim 11 in which all of said rigid plates are hexagonal in shape.

15. The armor of claim 11 in which the area relationship between each of the plates in one of said layers of rigid plates and each of said plates in the next adjacent said layer of rigid plates is substantially 1:4.

16. The armor of claim 11 in which the area relationship between each of the plates in one of said layers of rigid plates and each of the plates in the next adjacent said layer of rigid plates is substantially 123.2.

17. Armor adapted to restrain penetration of projectiles therethrough comprising a layer of rigid plates, a

layer of elastic material next adjacent below attached thereto, a second layer of rigid plates of identical shape below and attached to said elastic layer, each of the plates of said layer having an area at least two times greater than the area of each of the plates in the first layer and so arranged that none of the joints between plates in the second layer are directly below and parallel with any joint between plates in the first layer, and a second layer of elastic material below said second layer 9 10 of plates attached thereto, and means for holding together 1,758,296 Sehaumann May 13, 1930 said rigid plates and said elastic material. 2,279,110 Collins Nov. 22, 1937 2,399,184 Heekert Apr. 30, 1946 References Cited in the file of this patent 5 FOREIGN PATENTS UNITED STATES PATENTS 105,322 Great Britain May 3, 1917 1,021,804 Schneider Apr. 2, 1912 854,059 France Jan. 2, 1940

Claims

3. ARMOR ADAPTED TO RESTRAIN PENETRATION OF PROJECTILES THERETHROUGH , COMPRISING LAYERS OF RIGID PLATES HAVING LAMINATED THEREINBETWEEN LAYERS OF ELASTIC MATERIAL, AND MEANS FOR HOLDING SAID ELEMENTS TOGETHER, EACH OF SAID LAYERS OF RIGID PLATES COMPRISING PLATES HAVING EDGES ABUTTING, EACH OF THE PLATES IN EACH OF SAID LAYER OF RIGID PLATES HAVING AN AREA GREATER THAN THE AREA OF EACH OF THE PLATES IN THE NEXT ABOVE LAYER OF RIGID PLATES AND THE PLATES IN EACH LAYER BEING SO ARRANGED THAT NO POINT BETWEEN ANY TWO PLATES IS SUPERIMPOSED DIRECTLY ABOVE AND PARALLEL WITH ANY JOINT IN ANY NEXT ADJACENT LAYER OF RIGID PLATES.