DE3390383T1 - Multi-layer composite material with variable density - Google Patents

Description

MULTI-LAYER COMPOSITE MATERIAL WITH VARIABLE DENSITY

Technical area :

The invention relates to a new multi-layer composite material, particularly having a modulus of elasticity ratio to density and has a ratio of tear resistance to density that is above the corresponding Values of metals are, in particular of steel and titanium, as well as its applications for example Manufacture of bulletproof vests, armored and protective walls, girders, tennis rackets, skis, sailing boards, Watercraft, containers and the like.

Underlying state of the art :

Attempts have already been made in applications of the above called type the conventional materials such as metals and metallic alloys through composite materials to replace, which are much lighter and easier to shape, for example by compression molding.

One knows in particular laminates that are made with a Resin coated or impregnated boron fibers are made and the mechanical properties are quite satisfactory have, but their very high production price limits the applications. We also know that a material

rial such as sintered boron carbide has a high resistance to impacts or blows, however has what can be described as "fragile" behavior towards shock waves, its breaking being in expresses a sudden and complete collapse. In addition, this material must be used in a Temperature of more than 1500 ° C and its manufacturing price is extremely high.

One also knows the laminates with synthetic resin or Plastic material sheathed carbon fibers of the upper Range of values and their ratio of modulus of elasticity to density and breaking resistance to density very much are high. However, these materials have mediocre resistance to knocks or heavy blows and their fracture behavior is of what can be called "fragile" type. Furthermore, they are very high Manufacturing price on.

Laminates made from under the trademark "KEVLAR" have also been found on the market for some time. Commercially placed aramid fibers exist, however have a very high manufacturing price and insufficient resistance to compression and have shear action. These compounds of aramid fibers and plastic or synthetic resin are currently in the form of soft sheets or mats for the Used in making bulletproof vests. However, these soft mats on their own still prevent do not allow the passage of perforating projectiles and age relatively quickly when exposed to ultraviolet radiation are exposed.

Furthermore, composite materials are known that consist of two plat-

ten of a ductile material (metal or metal alloy) and that on a core of a plastic material are glued. However, this gluing does not always ensure the homogeneity of the entire arrangement, if that Composite material is exposed to mechanical loads or strong temperature increases due to the significant differences in mechanical properties and expansion coefficients between the panels of the ductile material and the plastic core.

Disclosure of the invention :

The invention aims at a lightweight composite material that has mechanical properties that are at least comparable to those of competing composite materials (e.g. based on aramid fibers) are comparable, but their production price is considerably lower than that of the Competing composite materials and which does not have the disadvantages mentioned above.

The multilayer composite material of the present invention comprises a middle layer woven from one another metallic or synthetic threads or fibers and is impregnated with a plastic material, as well as at least one outer cover layer and is characterized in that the density of the middle layer over their The thickness varies and increases from its central plane to its outer sides, the ratio of the density of the outer fibers to the density of the fibers in the median plane of the material has a value between 3 and 13.

This structure allows for variable density of the material

on the one hand to reduce the material weight, and on the other hand, a modulus of elasticity with regard to bending and obtain a moment of inertia in terms of bending and torsion, which are particularly favorable.

Depending on the type of application for which the composite material is determined, the plastic material soaking the middle layer can be rigid, semi-rigid or soft, wherein the outer cover layer can consist of a material that has a high surface hardness (for example Aluminum oxide or ceramic). The outer cover layer can, however, also consist of fibers that are embedded in a plastic material are immersed, identical or compatible with the plastic material soaking the woven mat is, the fibers of this outer cover layer, for example, those made of boron, carbon, glass or aramid could be.

In general, the composite material according to the invention prevents the passage of shock waves, for example resulting from the impact of a projectile, with at the same time, in certain applications, it prevents the projectile from passing through. This invention Composite material also has the advantage that it does not exhibit breakage behavior in the manner of a breakage when it is exposed to shock waves or impact and that it has a relatively very high elongation to tear.

In accordance with further features of the invention, the material comprises superposed woven layers of the foregoing called type, which are connected to each other and between which plates made of a rigid and hard material

material such as boron carbide, aluminum oxide, ceramic, titanium, etc. are arranged, these between two woven layers of rigid panels arranged by plastic-filled spaces from one another are separated and the plates arranged on both sides of a woven layer relative to one another in such a way are offset that they mutually overlap on both sides of this layer.

So you get depending on the panel dimensions a more or less soft structure that can be used to manufacture bulletproof vests or garments suitable.

According to further features of the invention, the composite material is in the form of a hollow profile with a circular, made of elongated or polygonal cross-section, the outer surface of which is a plastic layer higher Surface hardness includes. These properties exhibit in particular the manufacture of beams, rods, rods, frames, etc.

According to a further feature of the invention, which in particular Aimed at the manufacture of skis, the material comprises a middle layer made of a plastic such as an epoxy resin sandwiched between two woven layers of the aforementioned type is, the outer surfaces of which are each covered with a layer of plastic-coated fibers.

Best way to carry out the invention :

In the following description of exemplary embodiments

Reference is made to the accompanying drawings, in which:

1 shows a schematic sectional view of a first embodiment of the composite material according to the invention ;

Fig. 2 is a schematic section showing the application of the invention to the manufacture of a bulletproof Vest shows;

Fig. 3 is a schematic section showing a

further application of the invention to the production of a

Reinforcement element of a bulletproof vest known Kind shows;

FIG. 4 is a schematic sectional view of an armored or protective wall;

FIG. 5 is a schematic sectional view of a modified embodiment of the invention for bulletproof ones West;

6 is a schematic sectional view of a cellular carrier using the inventive Composite material;

Figures 7, 8 and 9 are cross-sectional views of structures of circular, rectangular and elongated, respectively Cross section using the material according to the invention;

FIG. 10 is a sectional view through an outsole of a ski using the one according to the invention

Materials.

Reference is first made to FIG. 1, which is a schematic partial section through an embodiment of the composite material according to the invention shows.

This composite material comprises a middle layer 10 made of interwoven metallic or synthetic Threads or fibers 12 is made and over their entire thickness and their entire surface with a plastic material 14 is impregnated, which, depending on the intended applications of the material, is rigid, semi-rigid or can be soft.

One side of the layer 10 is covered with at least one layer 16 of a material made up of fibers 19 consists, which are encased with a plastic material that is identical or compatible with the plastic material 14 with which the layer 10 is impregnated. The other side of the layer 10 is also covered with a layer 18 of a material consisting of fibers wrapped in a plastic material similar to that in Layer 16 case identical or compatible with the

the layer 10 is an impregnating plastic material. To Type of application, the material of the layer can be identical to that of the layer 16 or made of fibers that are different from those of layer 16. The thickness of the layer 18 can also be the same as or different from that of the layer 16. the The densities of these two layers can be the same or different from one another.

Thanks to the plastic material with which they are impregnated, the middle layer 10 and the outer layers 16 and 18 are closely connected to one another and hang thereon Way together without the risk of tearing or peeling if the composite material is very is exposed to hard mechanical loads.

The density of the middle layer is variable across its thickness and increases from its (parallel to the outer layers 16 and 18 directed) center plane towards their outer sides. The outer layers 16 and 18 can each have an essentially constant or also a variable density, which increases towards the outside such that in the multilayer composite material according to the invention the ratio of the density of the outer fibers to the fiber density in the central plane has a value from 3 to 13 has.

The composite material can be made by hot casting or cold casting under pressure or by injecting the plastic material be formed in a form, which one or more intended to form the layer 10 mats of metallic or synthetic fabric as well as sheets or mats woven from fibers, which are used to form the Layer 16 and layer 18 are determined.

The middle layer 10 can consist of several mats of a metallic or synthetic fabric or of a fabric consist of metallic or synthetic threads or fibers with a triple weave. These threads or Fibers may or may not be stainless steel fibers having a diameter less than or equal to 0.2 Threads made from a light metal alloy with high-quality mechanical properties or from a Mixture or combination of metallic Threads or fibers and synthetic threads or fibers are made.

The fibers used to form layers 16 and 18 can be boron fibers, carbon fibers, glass fibers, Be aramid fibers, etc. The ones to soak the middle class

and the materials used of layers 16 and 18 can be hot or cold pressure polymerizable Synthetic resins, a silicone elastomer, polyurethane, etc.

The composite material of the present invention has the following essentials Properties: Its values of the ratios of modulus of elasticity to density and tear resistance to density are considerably above the corresponding values of metals and in particular of steel and titanium, in particular when the layer 10 consists of a steel thread fabric. The composite material has a very good damping coefficient for mechanical and acoustic vibrations. The composite material has a very high degree of stretching up to the tear limit, with the tearing being progressive and partially done.

Reference is now made to Fig. 2, which shows an application of the invention for the manufacture of a bulletproof vest shows.

The structure shown in Fig. 2 comprises a certain number of mats 20 of variable density, im present case five, each a layer or a mat of interwoven metallic threads or Fibers include those with a soft plastic material is soaked and optionally on one side or both sides have a fiber layer impregnated with the same soft plastic material. Between Mats 20 are platelets 22 of a very hard material such as boron carbide or titanium, which arranged between two mats 20 at a distance from one another and on both sides of a mat 20 relative to one another are offset in such a way that the platelets lying on each side of a mat partially overlap.

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The platelets 22 have, for example, a length or a vertical dimension between 10 and 20 cm while its width or horizontal dimension is between 4 cm and 8 cm. The spaces 24, which separate the platelets 22 lying between two mats 20 are made of the same soft plastic material filled in during the formation of the entire structure. The thickness of the structure shown in FIG is, for example, approximately 4 mm. The soft plastic material with which the layers 20 are impregnated and that fills the spaces 24, ensures the connection between the various components this structure. The entire structure obtained in this way can be arranged between two textile materials, which form the inside and outside of the vest.

The structure shown in Fig. 2 is semi-rigid and suitable to adapt to the radii of curvature of a person's chest and back. This semi-rigid permit it moreover, part of the kinetic energy of a projectile due to deformation and displacement of the To absorb vest in the impact area. Furthermore The composition of the composite material made up of the layers 20 can cause an extension of one of the impacts Prevent resulting transverse shock wave, thereby affecting the sensitive parts or organs of the body be protected against this shock wave and the destruction of one or more small plates 22 is avoided that are not directly exposed to this shock wave.

In Fig. 3 a structure has been shown which is intended for reinforcement of known bulletproof vests is. This structure shows up in the form of a corrugated

Plate 26 made of a composite material according to the invention, which one arranges, for example, in a pocket, which is on the outside or open side through a certain Number of webs 28 made of aramid fibers laid one on top of the other and supported on the body side by a support material 30 is limited. The corrugated plate 26 comprises a middle layer of metal thread, which is connected to a semi-rigid Plastic material are soaked, and one is the middle layer covering outer layer 32 made of a very hard material such as ceramic or aluminum oxide, which can be applied to this outside by suitable means, such as by means of a Plasma torch or by metallization. Preferably, the corrugated plate 26 can be made of superimposed Layers of the composite material according to the invention formed which have a different density, the waves of this plate, which are attached to the support fabric 30 rest, have widened contact surfaces 34.

This structure can replace the steel plates commonly used in bags made of aramid fibers bulletproof vests are arranged. A particular disadvantage of these steel plates is that they Be too heavy and allow the propagation of shock waves, which are very dangerous for the sensitive Organs of the body are.

Reference is now made to FIG. 4, which shows a schematic partial section through an armored wall or protective wall, for example for a vehicle or a proximity sign and the like. This wall includes one Outer plate 36 made of titanium or another material with very high-quality mechanical properties, an inner plate 38 made of a composite material according to the invention and

a corrugated intermediate plate 40, which also consists of a composite material according to the invention. The inner panel 38 consists of a layer comprising a metal fabric which is impregnated with a rigid plastic and which carries on at least one of its faces a layer of a material based on fibers which are impregnated with the same rigid plastic material. The corrugated intermediate plate 40 consists of one layer a metal mesh covered with a semi-rigid synthetic cloth material is soaked.

Under the action of an impact on the outer plate 36, the corrugated plate 40 tends to flatten out, by absorbing a layer of the kinetic energy of the shock or shock and dampening the shock wave, at the same time preventing or limiting the transmission of this shock wave to the inner plate 38, the in turn has the tendency to absorb any shock waves that may be transmitted.

Fig. 5 shows a schematic partial section through a modified embodiment of an inventive bulletproof vest. The illustrated structure comprises a middle layer 42 of interwoven metal threads or fibers coated with a soft plastic material, for example a silicone elastomer or is impregnated with a high density polyurethane foam. The two surfaces of the middle layer 42 are with a Covered series of soft webs 44 made of fibers such as glass fibers or aramid fibers, in turn with a soft plastic, such as the same silicone elastomer as the Center plane 42 are soaked. The density of the metal threads or fibers forming the middle layer 42 increases

the middle plane of this layer up to its outer surfaces, the density in the middle plane for example has a value of the order of magnitude of 0.6 and a value of 3 on the outer surfaces with a medium one Density value between 1 and 2. The number of webs 44 covering each side of layer 42 is preferably between 7 and 10, the thickness of each sheet being about 0.2 mm to 0.4 mm. The tracks 44 can be made from different fibers can be made, for example the webs on the inside of the layer are made of fiberglass, while the webs on the outer surface of the layer 42 are made of carbon fibers, Ararnid fibers or made of metal fibers.

As an example it should be indicated that the webs 44 made of aramid fibers on the outside of the vest each have one Thickness of about 0.3 mm and a basis weight of

2
can be approximately 285 g per m. The webs 44 of fiberglass in conventional weave, which are provided on the inside of the vest, each have a thickness of about 0.2 mm and a basis weight

2
of about 200 g per m, these various sheets not being impregnated with plastic material.

The structure shown in Fig. 5 has a modulus of elasticity in bending and a moment of inertia in bending and torsion, the values of which are at least equal to those values of these sizes of similar structures made exclusively from aramid fibers or carbon fibers, the total density or mass of the structure is the same in the different cases. The structure shown in ^c of FIG. 5 according to the invention has a much lower cost price than the equivalent

Structures made of carbon fibers or aramid fibers.

The composite material according to the invention can also be used for production of sailboards or watercraft are used, in which case the ratio of the densities of the outer fibers to the fibers in the central plane of the material preferably has a value between 3 and 5, the middle plane has a thickness between 1 mm and 5 mm and preferably with a polyurethane foam or a synthetic resin is soaked through hollow spheres made of glass or an elastomer with a diameter made lighter by a few tenths of a millimeter. In this case, the outer layers consist of Layers of a three-directional fabric made of glass fibers, aramid fibers, carbon fibers or synthetic fibers.

The composite material according to the invention can also be used to produce ' used by multi-shell containers or watercraft, with the ratio of density of the outer fibers to the fibers in the central plane in this case preferably have a value between 4 and 7 owns. The outer layers consist of layers of knitted metal threads or metal fibers and of layers, those made of glass fibers, aramid fibers or carbon fibers are woven.

When the composite material of the invention to form armor is determined, the density ratio between outer fibers and fibers in the central plane preferably between 6 and 13 and you can put a layer of an elastomeric synthetic resin between the provide the middle layer and the outer layers mentioned above. These outer layers can in this case

be formed from a layer consisting of interwoven strips of amorphous cast and / or a Plate made of a metal alloy based on nickel or cobalt and / or a ceramic or aluminum oxide layer, which is preferably applied with the help of a plasma torch, with mats made of metallic or synthetic fibers optionally between these outer layers and the elastomeric plastic layer can be arranged.

The composite material according to the invention can also be used for production of pipes, beams, frames and the like. For example, that shown in FIG Material as a profile with a square, rectangular, polygonal, circular or elongated Cross-section are formed and comprises in this case at least on its outer surface from a cladding a preferably rigid plastic material such as high density polyurethane, which is a type Skin forms, that is, has a relatively high surface hardness. Such a profile can be hollow or be filled with a lightweight plastic material such as a high density polyurethane foam.

FIG. 6 shows, as an example, a schematic cross section through a cellular carrier made from an inventive Composite material.

This carrier is formed by two adjacent profiles made of the composite material according to the invention, whose rectangular cross-section is partially shown in FIG. 6 and each one of a metallic fabric include existing mat made with a rigid plastic material such as

High density polyurethane is impregnated with the two surfaces of this mat with a layer of this plastic material are covered, which optionally (for the outer surface of the mats 50) glass fibers and / or Contain carbon fibers that are applied, for example, using a gun.

The two profiles 50 are placed next to one another along one of their vertical long sides, with their horizontal upper and lower surfaces are covered with a metallic woven mat 52 rigid with the same Plastic material is soaked and spread over the entire extent of the beam extends. In the area of the connection between the two profiles is each of the metallic woven mats 52 are covered with a metallic woven tape 54, which is also connected to the named plastic material is impregnated, which forms an outer surface layer 56 of relatively high hardness. The profiles forming the support can be hollow or filled with a polyurethane foam or phenolic foam, if you want to improve thermal and acoustic insulation.

A carrier according to the invention can also be honeycomb-like Have structure and in this case consist of a plurality of adjacent profiles that are connected to one another in the manner described with reference to FIG.

7, 8 and 9 show tubular structures made of a composite material according to the invention, each of which comprise a framework 60 made of a mat woven from metallic or synthetic threads or fibers, with a rigid plastic material like both

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for example polyurethane is impregnated and its two surfaces with a layer 62, 64 of the same plastic material are covered, wherein the outer layer 62 is formed in the manner of a skin, that is a has a relatively high surface hardness. A fiber mat 66 impregnated with plastic material may be provided between the outer surface of the woven mat 60 and the outer plastic layer 62, wherein this mat 66 can be formed from a tube or from two bands, which are attached to the woven mat 60 in such a way are wound that they intersect at an angle between 10 ° and 45 °.

In FIG. 8, the inner plastic layer 64 has Stiffening ribs 68, which at the same time have the effect of guiding the plastic material during injection to facilitate. In the same way, the structure shown in FIG. 9 in the area of small axis of the oval cross-section of this structure a stiffener 70 made of plastic.

The structure shown in Fig. 7 is for example Can be used for ski poles, masts of sailing boats and pipelines. The structure of FIG. 8 is, for example Can be used for tennis racket frames as well as for skis if they have a suitable ratio of height to them Having width. The structure of FIG. 9 is for example for blades of water turbines as well as the blades of wind turbines. In these structures, the interior space can be empty or filled with a lightweight material which has a density of the order of 0.2.

Fig. 10 shows a partial section through a structure of a composite material according to the invention, the one Middle layer 72 made of a plastic material such as an epoxy resin, which is sandwiched between two woven mats 7 4 made of metallic fibers or threads are inserted, which are impregnated with a plastic material and the outer sides of which are each covered with a layer 76 of a plastic material, for example an epoxy resin are covered, which in turn are each covered by a layer 78 made of resin-impregnated fibers consists, wherein the fibers can be glass fibers, carbon fibers, aramid fibers or the like.

This structure can be used for the production of walls, in particular the bodies of motor vehicles, as well as for Manufacture of the upper and lower deck surfaces of a ski. In this case, the structure shown in FIG. 10 has a thickness of 2 mm to 3 mm and extends the entire length of the ski. Such the tread and the Structures forming the top surface of the ski allow very good damping of those caused by bending and torsion Vibrations as well as a very high torsional stiffness, which has a positive effect when cornering.

Claims (17)

Claims 1. A multilayer composite material comprising a middle layer, which consists of metallic or synthetic interwoven threads or fibers and with a plastic material is impregnated, and at least one outer cover layer, characterized in that the The density of the middle layer (10, 20, 26, 38, 40, 42) is variable across its thickness and from its central plane towards their outer surfaces increases, the ratio of the density of the outer fibers to the density of the fibers has a value between 3 and 13 in the median plane of the material. 2. Composite material according to claim 1, characterized in that said middle layer (10, 20, 26, 38, 40, 42) is formed by superimposing two mats woven from threads or fibers, these Mats have different densities. 3. Composite material according to claim 1, characterized in that g e k e η η, that said middle layer (10, 20, 26, 38, 40, 42) is made of metallic or synthetic Has threads or fibers woven mat, the density of which is variable over its thickness. 3390333. A * ~ 4. Composite material according to any 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 that through hollow balls is made lighter. 5. Composite material according to one of the preceding claims, characterized in that the outer Cover layer (16, 18) consists of fibers (19) which are embedded in a plastic material that with that is identical or compatible with which the middle layer (10) is impregnated. 6. Composite material according to claim 5, characterized in that g e k e η η, that the fibers (19) are boron fibers, carbon fibers, glass fibers or aramid fibers. 7. Composite material according to one of the preceding claims, , characterized in that the plastic material (14) impregnating said middle layer rigid, semi-rigid or soft material. 8. Composite material according to one of claims 1 to 4, g e indicates by an outer cover layer (32), which consists of a material layer of great hardness such as for example ceramic or aluminum oxide. 9. Composite material according to one of the preceding claims, characterized in that said Middle layer (26, 40) forms a corrugated plate. 10. Composite material according to claim 1, characterized in that g e k e η η - draws that they are an overlay of layers or mats (20) of the aforementioned type, which are connected to one another, and that panels (22) Rigid and hard material such as boron carbide inserted between the two layers or woven mats are. 11. Composite material according to claim 10, characterized in that there are at least three on top of each other includes laid mats (20), between which rigid plates (22) are inserted, the between two mats (20) arranged plates are separated from one another by spaces (24) filled with plastic and the Plates on both sides of a mat (20) are offset from one another in such a way that the one on one side of the The plates arranged in the mat overlap at least partially the plates lying on the other side of the mat, 12. Composite material according to claim 1, characterized in that g e k e η η, that said middle class (42) on their outer surfaces with a series of mats (44) which is woven from fibers such as glass fibers, carbon fibers or aramid fibers and optionally are impregnated with a soft plastic material. 25th 13. Composite material according to claim 4, characterized in that said middle layer (10) has a thickness of approximately 1 mm to 5 mm and that the outer cover layer (16, 18) is woven in three directions Fiber mats, the ratio of the density of the outer fibers to the density of the fibers in the middle plane has a value between 3 and 5. 3390833 14. Composite material according to one of claims 1 to 5, characterized in that the outer cover layer of metallic threads or fibers braided mats and mats made of threads or fibers Glass, carbon or aramid are made and are impregnated with a plastic material, with the ratio the density of the outer fibers to the density of the fibers in the median plane of the material has a value between 4 and 7 owns. 15. Composite material according to one of claims 1 to 4, g e indicates by a layer of an elastomeric resin between the middle layer and the outer cover layer is arranged, this made of interwoven strips of amorphous cast and / or a plate of a metallic alloy or a layer of ceramic or aluminum oxide and wherein the ratio of the density of the outer fibers to the density of the fibers in the midplane has a value between 6 and 13. 16. Composite material according to one of claims 1 to 3, characterized characterized in that it is in the case of a middle layer impregnated with a rigid plastic material (50, 60) made in the form of a hollow profile with a circular, elongated or polygonal cross-section is. 17. Composite material according to one of claims 1 to 3, characterized in that it is a layer (72) made of a plastic material such as an epoxy resin sandwiched between two middle layers (74) of the aforementioned type is arranged, which are impregnated with a rigid plastic material and the outer sides of which are each covered with a fiber layer (78) covered with a rigid plastic material is soaked.