WO1984002306A1

WO1984002306A1 - Variable density multilayer composite material

Info

Publication number: WO1984002306A1
Application number: PCT/FR1983/000250
Authority: WO
Inventors: Raymond Klein; Jean-Andre Loupere
Original assignee: Ind Plastique Mecanique
Priority date: 1982-12-13
Filing date: 1983-12-12
Publication date: 1984-06-21
Also published as: GB2141379B; GB8420409D0; FR2537502B1; JPS60500364A; FR2537502A1; GB2141379A; AU2332284A; DE3390383T1

Abstract

Multilayer composite material comprising a core layer (10) which is formed of woven synthetic or metal yarns or fibers (12), and which is impregnated with a plastic material (14), the density of said core layer being variable in its thickness and increasing from its medial plane up to its outer faces, the material further comprising at least one outer coating layer (16, 18) formed for example by yarns or fibers (19) embedded in a plastic material compatible with that of the medial or core layer (10), the outer fibers/medial plane density ratio of the material being comprised between 3 and 13.

Description

.VARIABLE DENSITY MULTI-LAYER COMPOSITE MATERIAL.

Technical area :

The invention relates to a new multi-layer composite material having in particular a modulus of elasticity / density ratio and a tensile strength / density ratio which are higher than those of metals, in particular steel and titanium, as well as as its applications, for example in the production of bullet-proof vests, shielding and protection walls, beams, tennis rackets, skis, sailboards, floating devices, tanks, etc.

PRIOR ART: ³ ζ We have already sought to replace, in applications of this kind, traditional materials such as metals and metal alloys by composite materials which are much lighter and more easily conformable, for example by molding.

Particularly known are laminated materials formed from boron fi¬ coated or impregnated with resin, which have entirely satisfactory mechanical performance, but whose extremely high cost price limits the applications. We also know that a material such as sintered boron carbide offers very high impact resistance, but has a behavior of the type called "fragile" to shock wave, its breaking resulting in its collapse and instantaneous ^• born. In addition, this material must be molded at a temperature above 1500 ° C and its cost price is extremely high.

Laminated materials are also known comprising high-end carbon fibers coated with resin or plastic material which have very high modulus of elasticity / density and breaking strength / density ratios. However, the resistance of these materials to impacts is poor and their rupture is of the so-called "fragile" type. They also have a very high cost price.

Laminated materials formed from aramid fibers marketed under the brand "KEVLAR" have also been available on the market for some time, but which have a high cost price and which have insufficient compressive and shear strength. . These aramid fiber and plastic or resin compounds are currently used in the form of flexible sheets for the production of bullet-proof vests. However, these flexible plies do not by themselves prevent the penetration of perforating bullets and age fairly quickly when they are subjected to ultraviolet radiation.

Also known are composite materials formed from two sheets of ductile material (metal or metal alloy) which are bonded to a core of plastic material. However, this bonding does not always ensure the homogeneity of the assembly when the composite material is subjected to mechanical stresses or to significant increases in temperature, due to the significant differences in mechanical characteristics and expansion coefficients between the plates. of ductile material and the core of plastic material.

WIPO E-opposite of the invention:

The subject of the invention is a light composite material, having mechanical characteristics at least comparable to those of competitive composite materials (for example based on aramid fibers), which has a cost price much lower than that of competing composite materials. and which does not have the disadvantages mentioned above.

The multilayer composite material according to the invention comprises a middle layer which is formed from woven metallic or synthetic threads or fibers and is impregnated with a plastic material, and at least one outer coating layer, and is characterized in that the density of the said median layer is variable in its thickness and increases from its median plane to its outer faces, the density ratio of outer fibers to median plane of the material being between 3 and 13.

This structure with variable density of the material makes it possible, on the one hand, to reduce the weight of the material and, on the other hand, to maintain a modulus of elasticity in bending and a module of inertia in bending and in torsion which are particularly efficient.

Depending on the applications for which this material is intended ^• -. composite, the plastic material which permeates the middle layer may be rigid, semi-rigid or flexible, the outer covering layer may be made of a material having a high surface hardness (for example alumina or ceramic) or else be formed from embedded fibers in a plastic material identical to or compatible with that which impregnates the woven sheet, the fibers of this outer coating layer may for example be fibers of boron, carbon glass or aramid.

In general, the composite material according to the invention prevents the transmission through it of shock waves resulting for example from the impact of a projectile, while preventing, in certain embodiments, the penetration of the projectile. This composite material according to the invention also has the advantage of not having a breakage of the fragile type when it undergoes shock waves or impacts, and of presenting a relatively very high rate of elongation at break. .

According to other characteristics of the invention, the material comprises a superposition of woven layers of the preci¬ type, which are integral with each other, and between les¬ which are interposed plates of rigid and hard material, such as boron carbide, alumina, ceramics, titanium, etc., these rigid plates arranged between two woven layers being separated from each other by intervals filled with plastic material and being offset from each other others on either side of a woven layer, so as to partially overlap on each side thereof.

Thus, depending on the dimensions of the plates, a more or less flexible structure is obtained which lends itself to the production of a waistcoat or a bulletproof clothing.

According to other characteristics of the invention, the composite material is produced in the form of a hollow section with a circular, oblong or polygonal section, the outer face of which comprises a layer of plastic material with high surface hardness. These characteristics relate more particularly to the production of beams, rods, bars, frames, etc.

According to yet another characteristic of 1 ^r inventio, which relates more particularly to the manufacture of skis, the airspace comprises a middle layer of a plastic material ^• such as an epoxy resin, interposed between two woven layers of the aforementioned type, the external faces are overlapped

WIPO WIPO green with a layer of fibers coated with plastic.

Best3-way_ _. to realize the invention:

In ^{'ladescription} which follows, given as an example, reference is made to the accompanying drawings, wherein:

- Figure 1 is a schematic view in section of a leading ^one embodiment of the composite material according to the invention;

- Figure 2 is a schematic sectional view illustrating the application of the invention to the production of a bulletproof vest;

- Figure 3 is a schematic sectional view illustrating another application of the invention to the production of a reinforcement piece of a bulletproof vest of a known type;

- Figure 4 is a schematic sectional view of a shielding or protective wall;

- Figure 5 is a schematic sectional view of an alternative embodiment of the invention, for bulletproof vests;

- Figure 6 is a schematic sectional view of a cellular beam using the composite material according to the invention;

- Figures 7, 8 and 9 are cross-sectional views of structures with circular, rectangular and oblong sections respectively, using the material according to the invention;

- Figure 10 is a sectional view of a ski sole using the material according to the invention.

Reference is first made to FIG. 1, which is a partial diagrammatic view in section of an embodiment of the composite material according to the invention.

WIPO This composite material comprises a middle layer 10 formed of woven wires or of metallic or synthetic fibers 12, - which is impregnated over its entire thickness and throughout its thickness with a plastic material 14 which may be of the rigid, semi-rigid type. or flexible, depending on the intended applications of the material.

One face of the layer 10 is covered with at least one layer 16 of a material formed of fibers 19 coated with a plastic material which is identical to or compatible with the plastic material 14 permeating the layer 10. The other face of the layer 10 is also covered with a layer 18 of a material formed of fibers coated with a plastic material which can be identical to the plastic material impregnating the layer 10 or compatible with it, as in the case of the layer 16. Depending on the case, the material of the layer 18 may be identical to that of the layer 16 or may be formed of different fibers. The thickness of the layer 18 can be equal to that of the layer 16, or else different; the densities of these two layers can be equal, or else different from each other.

Thanks to the plastic material with which they are impregnated, the middle layer 10 and the outer layers 16 and 18 are intimately connected to each other and are thus bonded together without risk of tearing or detachment when the composite material is subjected to very severe mechanical stress.

The density of the middle layer 10 is variable in its thickness and increases from its median plane (parallel to the outer layers 16 and 18) to its outer faces. The outer layers 16 and 18 may each have a substantially constant density, or else have a variable density increasing towards the outside, so that, ^• in the thickness of the multilayer composite material according to the invention, the fiber density ratio outdoor-plan median is between 3 and 13.

This composite material can be formed by hot molding, or cold molding under pressure, or by injection of the plastic material into a mold containing one or more layers of metallic or synthetic fabric intended to form the layer 10 and of the plates or layers woven with fibers intended to form layer 16 and layer 18.

The middle layer 10 can be formed from several layers of a metallic or synthetic fabric or else be formed by three-way weaving of metallic or synthetic threads or fibers. These wires or the fibers may be stainless steel wires having a diameter less than or equal to 0.2 mm, or else light metal alloy wires with high mechanical characteristics, or else be a mixture or a combination of wires or metallic fibers and synthetic yarns or fibers.

The fibers used to form layers 16 and 18 can be boron, carbon, glass fibers, aramid fibers, etc. The materials used to impregnate the middle layer 10 and the layers 16 and 18 can be poly erisable resins hot or cold under pressure, a silicone elastomer, polyurethane, etc.

The composite material according to the invention has the essential property of having modulus of elasticity / density and breaking strength / density ratios which are much higher than those of metals and in particular of steel and titanium, in particular when the layer 10 is made of fabric of steel wires, to have a very good damping coefficient for mechanical and acoustic vibrations, to have a very high rate of elongation at break, the breakage being progressive and partial.

We now refer to Figure 2, which represents a

WIPO application of the invention to the production of a bulletproof vest.

The structure shown in FIG. 2 comprises a certain number of plies 20 of variable density, which here are five in number and which each comprise a layer or ply of woven metal wires or fibers impregnated with a flexible plastic material and optionally comprising on one or two sides a layer of fibers impregnated with the same flexible plastic material. Between the plies 20 are disposed pla¬ 22 of a very hard material such as boron carbide or titanium which are spaced from one another between two plies 20 and which are offset relative to each other by side of a sheet 20, so as to Che ^• vaucher partially on each side of the web. The plates 22 have, for example, a length or a vertical dimension between 10 and 20 centimeters, and a width or a horizontal dimension between 4 and 8 centimeters. The intervals 24 separating the plates 22 between two layers 20 are filled with the same flexible plastic material during the molding of the entire structure. The thickness of the structure shown in FIG. 2 is for example around 4 mm. The flexible plastic material which permeates the plies 20 and which lines the gaps 24 ensures the connection between the various components of this structure. The assembly thus obtained can be placed between two textile fabrics forming the external and internal faces of the vest.

The structure shown in Figure 2 is of the semi-rigid type and lends itself to the radii of curvature of a person's chest and back. This semi-rigidity also makes it possible to absorb part of the kinetic energy of a projectile, by deformation and displacement of the vest in the area of impact. In addition, the structure of the composite material forming the plies 20 makes it possible to avoid transverse propagation ^• of the shock probe resulting from the impact, which protects from this shock wave the sensitive parts or organs of the body.

O PI IPO y

and also prevents the destruction of one or more plates 22 which are not directly subjected to this. shock wave. ι There is shown in Figure 3 a structure intended to reinforce bulletproof vests of a known type. This structure is in the form of a corrugated plate 26 of composite material according to the invention, which is placed for example in a pocket formed, on the outside or impact side, by a number of superimposed sheets 28 of fibers aramid and, on the body side, by a retaining cloth 30. The corrugated plate 26 comprises a middle layer of metal wires impregnated with a semi-rigid plastic material, and an outer layer 32 of coating of very hard material, such as ceramic or alumina, which can be deposited on this outer face by any suitable means, for example by a plasma torch or by metallization. Advantageously, the corrugated plate 26 can be formed of a superposition of layers of composite material according to the invention having different densities, and the corrugations of this plate which are in contact with the retaining fabric 30 form bases widened 34.

This structure makes it possible to replace the steel plates which are usually placed in the pockets of known bullet-proof vests made of aramid fibers. These steel plates have in particular the disadvantages of having an excessively large weight and of allowing the transmission of shock waves, which are very dangerous for the sensitive organs of the body.

Reference is now made to FIG. 4 which is a diagrammatic view in partial section of a shielding or protection wall, for example for a vehicle, for an approach shield, etc. This wall comprises an outer plate 36 of titanium or any other material having very high mechanical characteristics, an inner plate 38 of composite material according to the invention, and an intermediate corrugated plate. diary 40 also made of composite material according to the invention. The internal plate 38 is formed of a woven layer of metalli¬ that impregnated with a rigid plastic material and at least one face of which comprises a layer of a material based on fibers impregnated with the same rigid plastic material. The intermediate corrugated plate 40 is formed from a metallic woven layer impregnated with a semi-rigid plastic material.

Under the effect of a shock on the external plate 36, the corrugated plate 40 tends to flatten by absorbing a layer of the kinetic energy of the shock or impact and to dampen the shock wave, while by preventing or limiting its transmission to the internal plate 38 which itself tends to absorb the shock wave possibly transmitted.

Figure 5 shows a partial schematic sectional view of an alternative embodiment of a bulletproof vest according to the invention. The structure shown comprises a middle layer 42 of woven wires or metallic fibers which is impregnated with a flexible plastic material, for example a silicone elastomer, or with a high density polyurethane foam. The two faces of the middle layer 42 are: covered with a series of flexible layers 44 of fibers such as glass or aramid fibers, which are impregnated with a flexible plastic material, for example of the same silicone elastomer than the median ply 42. The density of the wires or metallic fibers forming the median layer 42 increases from the median plane of this ply to its dull faces, the density being for example of the order of 0.6 in the median plane and 3 on the outer faces, with an average density between 1 and 2. The number of plies 44 on each face of layer 42 is advantageously between 7 and 10, the thickness of each ply being comprised between 0.2 and 0.4 mm approximately. The layers 44 can • be formed from different fibers, the layers on the internal face of the layer 42 being for example made of glass fibers while the layers on the external face of the layer

WIPO 42 are made of carbon fibers, aramid fibers, or even metallic fibers.

By way of example, it will be specified that the sheets 44 of aramid fibers on the external side of the vest may each have a thickness of approximately 0.3 mm and a weight of approximately 285 g / m2, and the sheets 44 of fiber Traditional weaving glass provided on the inside of the vest each has a thickness of approximately 0.2 mm and a weight of approximately 200 g / m2, these various layers being not impregnated with a plastic material.

The structure of FIG. 5 has a modulus of elasticity in bending and a module of inertia in bending and in torsion which are at least equal to those of equivalent structures made only of aramid fibers or carbon fibers, the density overall or the mass of the structure being substantially the same in the different cases. The structure according to the invention shown in FIG. 5 has a cost price much lower than that of equivalent structures made of carbon fibers or aramid fibers.

The composite material according to the invention can also be used for the production of sailboards or floating devices and in this case, the density ratio of exterior fibers to median plane of the material is between 3 and 5 preferably, the median layer having a thickness of between 1 and 5 mm and being preferably impregnated with polyurethane foam or a resin lightened by hollow spheres of glass or elastomer having a diameter of a few tenths of a millimeter , the outer layers then being made up of three-way woven plies of glass fibers, aramid, carbon or synthetic fibers.

The composite material according to the invention can also be used for the manufacture of tanks or multi-hull floating floats, the density ratio of external fibers-

WIPO IPO median plane then being preferably between 4 and 7, the outer layers consisting of plies of son - or braided metal fibers, and woven plies of glass fibers, aramid or carbon ι.

When the composite material according to the invention is intended to form a shielding, the density ratio of external fibers to the median plane is preferably between 6 and 13 and a layer of elastomeric resin can be provided between the aforementioned median layer and the outer layers. These outer layers can then be formed of a layer of ribbonswoven in amorphous cast iron, and / or of a metal alloy plate based on nickel or cobalt, and / or of a layer of ceramic or alumina preferably deposited. with a plasma torch, sheets of metallic or synthetic fibers which may possibly be interposed between these outer layers and the layer of elastomeric resin.

The composite material according to the invention can also be used for the production of tubes, beams, frames, etc. For example, the material of FIG. 1 can be shaped as a section with a square, rectangular, polygonal, circular or oblong section and then comprises, at least on its outer face, a coating of preferably rigid plastic material such as polyurethane. high density with skin effect, that is to say having a relatively high surface hardness. Such a profile can be hollow or filled with a light plastic material, for example a high density polyurethane foam.

FIG. 6 represents, by way of example, a cross-section through a tick of a honeycomb beam of composite material according to the invention.

This beam is formed by the juxtaposition of two profiles made of ^• composite material according to the invention, the rectangular cross section of which is partly shown in FIG. gure 6, and which each comprise a metalli¬ that woven sheet 50 impregnated with a rigid plastic material such as high density polyurethane, the two faces of this sheet 50 being covered with a layer of this plastic material, optionally comprising ( for the outer face of the layers 50) of glass and / or carbon fibers, for example sprayed with a gun.

The two sections 50 are juxtaposed along one of their longitudinal vertical faces, and their upper and lower horizontal faces are covered with a metallic woven sheet 52 impregnated with the same rigid plastic material and extending above all the extent of the beam . At the junction between the two sections, each metallic woven sheet 52 is covered with a metallic woven strip 54 also impregnated with said plastic material which forms an outer surface layer 56 of relatively high hardness. The profiles forming the beam can be empty or filled with polyurethane or phenolic foam if thermal and acoustic insulation is to be improved.

A beam according to the invention can also have a structure of the honeycomb type and then be formed from a plurality of profiles juxtaposed and assembled to each other as described with reference to FIG. 6.

FIGS. 7, 8 and 9 represent tubular structures of composite material according to the invention which each comprise a framework 60 formed of a sheet woven of metallic or synthetic fibers or yarns, impregnated with a rigid plastic material such as polyurethane, and the two faces of which are covered with a layer 62, 64 of the same plastic material, the outer layer 62 having a skin effect, that is to say having a relatively high surface hardness. Optionally, a sheet 66 of fibers impregnated with plastic material can be provided between the outer face of the woven ply 60 and the outer layer 62 of plastic, this ply 66 consisting of a tube or ^one of two strips wound on the woven ply 60 while growing at an angle between 10 and 45 ° .

In FIG. 8, the internal layer of plastic material 64 has stiffening ribs 68 which also have the effect of promoting the routing of the plastic material by injection. Likewise, the structure of FIG. 9 comprises a stiffener 70 made of plastic, at the level of the minor axis of the oblong cross section of this structure.

The structure of FIG. 7 is applicable, for example, to ski poles, to sailboat masts, to pipes. The structure of FIG. 8 is applicable, for example, to tennis racket frames, as well as to skis when it has an appropriate height / width ratio. The structure of FIG. 9 is applicable, for example, to blades of hydraulic turbines and to wind turbine blades. In these structures, the internal space can be empty or lined with a light material having a density of the order of 0.2.

Figure 10 is a partial sectional view of a structure of composite material according to the invention, which comprises a middle layer 72 of a plastic material such as an epoxy resin, placed between two woven plies 74 of son or fi ¬ metallic berries, impregnated with plastic material, the outer faces of which are each covered with a layer 76 of plastic material such as an epoxy resin, itself covered with a layer 78 of material formed from fibers impregnated with resin , the fibers possibly being glass, carbon, aramid fibers, etc.

This structure is applicable to the production of walls, in particular motor vehicle bodies, and ^• that achieving the top and bottom flanges of a ski. In this case, the structure of Figure 10 has a

- ^ TslÀ ^

O PI thickness between 2 and 3 mm and extends all along the ski. Such structures forming the upper and lower soles of a ski allow very good damping of bending and torsional vibrations, and a very high torsional stiffness, favorable for grips on edges.

WIPO

Claims

Patent claims:

1. A multilayer composite material, comprising a middle layer which is formed from woven metallic or synthetic threads or fibers and which is impregnated with a plastic material, and at least one outer coating layer, characterized in that the density of said middle layer (10, 20, 26, 38, 40, 42) is variable in its thickness and increases from its median plane to its outer faces, the density ratio of outer fibers to median plane of the material being between 3 and 13.

2. Material according to claim 1, characterized in that said middle layer (10, 20, 26, 38, 40, 42) is formed of a superposition of woven plies of son or fibers, these plies having different densities.

3. Material according to claim 1, characterized in that said middle layer (10, 20, 26, 38, 40, 42) comprises a web woven of metallic or synthetic threads or fibers, this web being of variable density in its thickness.

4. Material according to one of the preceding claims, characterized in that said middle layer (10, 20, 26, 38, 40,42) is impregnated with a polyurethane foam or a resin lightened by hollow spheres.

5. Material according to one of the preceding claims, characterized in that the outer covering layer (16, 18) is formed of fibers (19) embedded in a plastic material identical to or compatible with that which permeates said middle layer (10).

6. Material according to claim 5, characterized in that the fibers (19) are boron, carbon, glass or aramid fibers.

7. Material according to one of the preceding claims.

-gJB.EX

WIPO characterized in that the plastic material (14) impregnating said middle layer is of the rigid, semi-rigid or flexible type.

8. Material according to one of claims 1 to 4, characterized by an outer coating layer (32) formed by a layer of high hardness material such as ceramic or alumina.

9. Material according to one of the preceding claims, characterized in that said middle layer (26, 40) forms a corrugated plate.

10. Material according to claim 1, characterized in that it comprises a superposition of layers or plies (20) of the aforementioned type, integral with each other, and in that plates (22) of rigid and hard material, such as boron carbide, are interposed between two woven layers or layers.

11. Material according to claim 10, characterized in that it comprises at least three woven plies (20) superpo¬ placed between which are rigid plates (22), the plates disposed between two plies (20) being separated one others by intervals (24) filled with plastic material and being offset with respect to each other on either side of a sheet (20) so as to partially overlap on either side of the sheet.

12. Material according to claim 1, characterized in that said middle layer (42) is integral, by its outer faces, with a series of plies (44) of woven fibers such as glass fibers, carbon or aramid, which are optionally impregnated with a flexible plastic material.

13. Material according to claim 4, characterized in that

WIPO said middle layer (10) has a thickness of between 1 and 5 mm approximately, and the outer covering layer (16, 18) is formed from three-way woven fiber plies, the density ratio of outside fibers to median plane being between 3 and 5.

14. Material according to one of claims 1 to 5, caracté¬ ized in that the outer coating layer is consti¬ killed plies of son or braided metal fibers and plies of son or glass fibers, carbon or aramid impregnated with plastic, the density ratio of exterior fibers to median plane of the material being between 4 and 7.

15. Material according to one of claims 1 to 4, characterized in that a layer of elastomeric resin is interposed between said middle layer and the outer coating layer, the latter being formed from amor¬ cast iron ribbons phe and / or a metal alloy plate or a layer of ceramic or alumina, the density ratio of exterior fibers to median plane being between 6 and 13.

16. Composite material according to one of claims 1 to 3, characterized in that, the middle layer (50, 60) being impregnated with a rigid plastic material, it is produced in the form of a hollow section section circular, oblong or polygonal.

17. Composite material according to one of claims 1 to 3, characterized in that it comprises a layer (72) of a plastic material such as an epoxy resin, interposed between two middle layers (74) of the aforementioned type, impregnated with a rigid plastic material, and the external faces of which. are each covered with a layer (78) of fibers impregnated with a rigid plastic material.

-TOSE

WIPO IPO