DE202007003209U1 - Multilayer laminate material with alternating layers of fibre and elastic knitted fabric in a resin matrix, used e.g. in aerospace applications, medical technology, car production, motor sport and design elements - Google Patents

Abstract

Multilayer laminate material (I) for slabs and moulded products, comprising fibre-reinforced plastic (preferably made by an autoclave process) with at least one layer of fibres (A) and at least one additional layer consisting of essentially uniform knitted fabric (B).

Description

The The present invention relates to a multilayer laminate material for plates and shaped bodies preferably made by autoclaving fiber-reinforced plastic with at least one fiber layer and at least one additional layer.

Fiber-plastic composites have been used for many years instead of metal since they have a tensile strength comparable to steel in the fiber direction, however, the weight is only about one-fourteenth. Fiber-reinforced plastics usually have high specific stiffnesses and strengths on, so they for Applications in lightweight construction are particularly well suited. The thermal and mechanical properties of such fibrous materials can be over various Parameters are set. In addition to the fiber-matrix combination, e.g. the fiber angle, the fiber volume fraction or the layer order be varied. In particular, fiber-reinforced plastics are in the last few Years of vehicle construction and used in aviation as well as in sports been to as possible low weight a big one To achieve rigidity. To mention are doing wing construction, Fairings and monocoques (motorsport) safer and with a wide range of performance to design. For these applications are called fiber structure u. a. Aramid fabric or Hygienic fabric used.

Fiber-reinforced plastics belong for a long time the state of the art. Also, it is already known to introduce an additional layer between two fiber layers.

The DE 40 02 062 A1 discloses a fiber reinforced plastic in which a plurality of layers of fibrous material of a predetermined type and nature are laminated to one another by means of a plastic, the layers being formed between the fibrous layers of thermoplastic material. In particular, the disclosed fiber-reinforced plastic to work safety and serve as it penetrates the material, for example, by breaking out workpieces, protect the persons behind the protection from injury by secondary splinters. The disadvantage here is that the fiber-reinforced plastic can completely break under unfavorable load and splinter and fiber parts are discharged from the component into the environment at high speed.

In the DE 10 2004 024 878 A1 is disclosed a sandwich element with two outer layers and a central layer arranged therebetween, wherein the central layer is formed as a curved shell structure and can also be formed in a described embodiment of a mesh made of plastic. With this arrangement, the sandwich component should have good stiffness and carrying capacity with low weight. A disadvantage of the disclosed subject matter is that the sandwich element breaks or shatters in the event of breakage and the breakage or splinter parts can adversely affect third parties.

Also in the fiber-plastic composites currently used in motorsport break and splinter outside components mounted on the vehicles, such as spoilers, diffusers, Cover and the like in an impact against another Vehicle or any object of the track boundary and will be over distributed the roadway. Subsequent vehicles may contact the sharp-edged one Splintering easily damage the tires, resulting in a significant Risk for the driver and other participants grow up.

Of the Invention is based on the object, a multilayer laminate material which, in the event of a break, is a chipping a component made therefrom and the fibers prevented and keep the fractions together.

These Task is solved by that the at least one additional layer of the multilayer laminate material a substantially uniform knitted fabric is.

With According to the invention, it is advantageously possible to provide a component face that opposite a conventional one Carbon part with exclusively several fiber layers with identical number of layers a higher stiffness having a lower weight and substantially unchanged thickness. Preferably can the multilayer laminate material according to the invention produced by the autoclave method or the wet laminate method become.

advantageously, are at a fraction of the component, i. the fiber structure with the matrix, the fragments held together by the knit as a unit. The mat-like Knitted fabric remains stretchy and elastic even in the case of breakage. At the Break the filaments of the knitted fabric and hold the fragments firmly together. Splintering of the fibers can be prevented and thus also a danger for Third parties are excluded due to fiber splinters. Perhaps at the fraction formed fiber fragments stick to the defective component and are not released into the environment. Mostly, the fractions only at a second considerable force, in particular in the shear direction to the breaking point, to be separated.

It is also advantageous that the multilayer laminate material is constructed as a kind of sandwich, wherein alternately several fiber layers and knitted fabrics could be arranged one above the other. It is also possible and favorable to manufacture a component from only two fiber layers with knitted fabric layers arranged therebetween.

The particular advantages of the knit are in the three-dimensional Wickerwork, creating a complete Breakage of the component can be prevented. Furthermore, the three-dimensional bears Training the knit to the fact that the fiber-reinforced plastic according to the invention can be broken repeatedly and in all directions, without the fragments be separated. It is also advantageously possible that material of the invention over cross to break without separating parts. The fragments will be always held together by the elastic knitted fabric.

Also it is advantageous that according to the invention a knitted fabric of a monofilament or a multifilament thermoplastic. For example could Kulierwirkware, warp knit fabric or the like are used.

Especially Cheap is to use a thermoplastic knitted fabric, wherein as a thermoplastic advantageously Polyester, polyamide, polyurethane, polymethylmethacrylate, polycarbonate or the like can be used. In particular, materials advantageous, both in the wet laminate and in the autoclave process can be used and the desired elasticity ensure the knitted fabric in the finished component.

When Fiber layer can favorably Carbon fibers, glass fibers, aramid fibers or a hybrid fabric used become. The layers can in this case be formed as mats and those of the prior art have known fabric structure with alternately crossing transverse and longitudinal fibers.

advantageously, are the fiber layers with a matrix material, preferably with soaked in a resin, wherein the multilayer laminate material according to the invention is independent of a particular resin system, i. it can be for the respective Application of the multilayer laminate material either a thermoset Matrix material, an elastomeric matrix material or a thermoplasti shear Matrix material can be used. While the synthetic resins and elastomers until it cures liquid are present, thermoplastics are solid to about 150 ° C. The thermoset Synthetic resins are usually glassy and do not deform plastic. Fiber-reinforced plastics Thermoplastics can be thermoformed with heat afterwards. As thermoplastics can for example, polyetheretherketone (PEEK), polyphenylene sulphide (PPS), Polysulfone (PSU) or polyetherimide (PEI) can be used. With a certain resin surplus At the fibers, the knitted fabric between the fiber layers during manufacturing process be firmly integrated.

It is cheap, that the thickness of the multilayer laminate material exceeds the number of alternating ones Layers can be determined. It is particularly advantageous that three Layers (2 fiber layers with intermediate knitted fabric layer) the multilayer laminate material according to the invention can form wherein the increase in thickness of the component by a thin knitted fabric is particularly low (in the range of 0.2mm to 0.5mm) can fail. This is special for fine Components of aerodynamics, e.g. cheap in motorsport for spoilers or wings and necessary.

Also It is advantageous that the mesh size of the knitted fabric at train or Pressure load is changeable at a break point. If the component is broken is and the individual fractions only through the knit together are held Relative movements of the fragments realized by a variable mesh size and thus greater security of holding together in the broken state. The variable Mesh size supported thus by the elasticity of the Gewirkes existing agility of the fragments.

It is also advantageous that the multilayer laminate material in a Temperature range between -40 ° C and + 250 ° C used can be without the positive properties of the knitted fabric would be impaired. For example This is especially true of vehicles, in hot areas near the engine or the exhaust system Cheap.

Also it is advantageous that from the multilayer laminate material a prepreg, i. a preimpregnated Tissue is producible. By the machine impregnation of the fibers of the multilayer laminate material can be a particularly preferred ratio between resin amount and Fiber number can be achieved. Especially beneficial for education of prepregs are carbon fibers.

Especially Cheap is the use of the multilayer laminate material of the invention in the field of aerospace, medical technology, automotive engineering, for motorsport, for Tuning parts or design elements, in general mechanical engineering or always when it comes down to, splinter-protected components with high rigidity to use at low weight.

Further Advantages of the invention will be described below together with the description a preferred embodiment of the invention with reference to the figures shown in more detail. Show it:

1 an exploded view of a plate-shaped multilayer laminate material,

2 an enlarged view from above of a layer of the multilayer laminate material,

3 a highly magnified photographic representation of a knitted fabric with a cut edge in plan view,

4 a photographic greatly enlarged representation of the knitted fabric 3 in a view from below.

In 1 is the multilayer laminate material 1 simplified as a planar plate body shown in an exploded view. In the case of shaped bodies, the structure of the multilayer laminate material according to the invention is 1 identical. In this embodiment, the multilayer laminate material is 1 from a flat upper fiber layer 2 , an elastic knitted fabric 4 and a flat lower fiber layer 3 formed into a kind of sandwich. The thickness of the multilayer laminate material 1 is about the number of alternating layers 2 . 3 . 4 certainly. The resin system (not explicitly shown) is arbitrary. Depending on the application, either a thermosetting matrix material, an elastomeric matrix material or a thermoplastic matrix material can be used. Polyetheretherketone (PEEK), polyphenylene sulphide (PPS), polysulphone (PSU) or polyetherimide (PEI) are frequently used as thermoplastics. To increase the thickness of the multilayer laminate material 1 It is possible from top to bottom more knitted layers 4 and fiber layers 2 . 3 alternately arrange, so that always a fiber layer 2 . 3 a knitted fabric 4 follows and vice versa. As the top and bottom layer preferably a fiber layer is arranged. It is understood that any desired positional arrangement may be provided. The multilayer laminate material 1 It can be used in a temperature range between -40 ° C and + 250 ° C without affecting the positive properties of the knitted fabric 4 or the positive effect of non-splintering in the event of a break in the fiber layers 2 . 3 would be negatively affected.

For clarification, the fiber layer 2 partially broken, leaving the tissue structure 5 the fibers can be seen. In the fabric structure shown 5 Fiber groups are laid so that the x-axis fibers 6 successively under two y-axis fibers 7 and then over two y-axis fibers 7 run. Likewise, the y-axis fibers run 7 under two and then over two x-axis fibers 6 , This structure is exemplary only, as are other equivalent tissue structures known in the art 5 , such as in 2 shown, usable. The fiber layers 2 . 3 Depending on the application, identical or different tissue structures can be used 5 exhibit. The fibers used are preferably carbon fibers, glass fibers, aramid fibers or a hybrid fabric. It can in the different fiber layers 2 . 3 be considered different fiber types.

In 3 is an example schematically a preferably used in the invention knitted fabric 4 shown in a view from above. The knitted fabric 4 is intersected at the top and rake side edge for illustration purposes. In contrast to a fabric structure in which a two-dimensional product is formed, the knitted fabric used is 4 three-dimensional. Preferably, the knitted fabric is 4 monofilament and made of an elastic thermoplastic fibers, but it is also the use of a multifilament knitted fabric 4 possible.

In a middle horizontal plane wavy filaments run 8th in the direction of the x-axis, wherein the respective longitudinally upper region of the wavy filament 8th in the unstretched state at least partially in the wave of the overlying wavy filament 8th extends. The respective lower portions of the shafts engage each other in a corresponding manner. A mesh filament 9 runs three-dimensional above and below the undulating filaments 8th , wherein the individual meshes mesh with each other in such a way that in the inner regions at the head and at the foot of a shaft 9 each node 10 . 10 ' are formed and thus a link between the two filaments 8th . 9 is made. At the nodes 10 the mesh filaments cross each other 9 in the upper part of the waveform of the filament duck 8th , at the nodes 10 ' in the lower part of the waveform of the filaments 8th , Between the respective nodes 10 or 10 ' shows the knitted fabric 4 an open loop 11 on. When loaded in the transverse direction, the undulating filaments slide 8th in the longitudinal direction into each other. The mesh filaments 9 are pulled apart at a lateral load, so that the nodes 10 and 10 ' from the upper and lower regions of the undulating filaments 9 towards the middle of the stitches 11 move. At a tensile load in the longitudinal direction limit the mesh filaments 9 at the nodes 10 . 10 ' a pulling apart of the wavy filaments 9 , only the stitches 11 , are stretched more in the longitudinal direction and thus longer and narrower. After a load the knitted fabric goes 4 due to the elasticity returns to its original state.

In 4 is the representation of 3 shown from the back side. The cut edges of the knitted fabric 4 are therefore on the lower and right side. The mesh filaments 9 run at the nodes 10 in the upper portion of the wave of the undulating filament in this figure 8th from one in the direction of the x-axis above the middle level of the filaments 8th lie the plane in one in the direction of the x-axis below the plane of the filaments 8th lying plane, and at the nodes 10 ' in the lower part of the wave of the undulating filament 8th vice versa. The wavy filaments 8th be in their adjacent areas 12 each of a mesh element 9 entwined. The mesh filament 9 runs to the adjoining area 12 to an associated node 10 or 10 ' ,

In a fraction of the multilayer laminate material according to the invention 1 can be prevented by means of the elastic three-dimensionally knitted plastic layer separation of the fragments, as happens in the prior art. The knitted fabric 4 retains its elasticity and allows the fragments through the filaments at a break point 8th , the mesh filaments 9 and her in the 3 and 4 shown special effect to hold elastically together, even if the fiber layers are completely broken.

In a preferred embodiment, the knitted fabric 4 a commodity usable width of 1350 +/- 20 mm and a basis weight of 120 +/- 8 g / m ² . At a longitudinal load of 100N, the knitted fabric can 4 by about 35%, with a lateral load of 100N by about 18% stretch. The stitch delay with the measuring staff / measuring tape method is approx. +/- 20 mm. The thermal shrinkage at 180 ° C is less than 3% in the longitudinal and transverse directions.

From the multilayer laminate material 1 is a prepreg (not shown), ie a prepreg fabric produced. Due to the mechanical impregnation of the fiber layers 2 . 3 of the multilayer laminate material 1 is a particularly preferred ratio between resin amount and number of fibers to achieve.

The multilayer laminate material 1 according to the invention in the field of aerospace, medical technology, automotive, motorsport, for tuning parts or design elements, in general mechanical engineering or whenever it is important to achieve a high stiffness with low weight, usable.

Claims (15)

Multilayer laminate material for plates and shaped articles preferably produced in the autoclave fiber-reinforced plastic With at least one fiber layer and at least one additional layer, the consists of a substantially uniform knitted fabric. Multilayer laminate material according to claim 1, characterized characterized in that several layers of fibers and knitted fabric alternately arranged in a kind of sandwich on top of each other. Multilayer laminate material according to claim 1 or 2, characterized in that the knitted fabric is formed in three dimensions is. Multilayer laminate material according to one of claims 1 to 3, characterized in that the knitted fabric is elastic and off a thermoplastic monofilament is formed. Multilayer laminate material according to one of claims 1 to 3, characterized in that the knitted fabric is elastic and off a thermoplastic multifilament is formed. Multilayer laminate material according to one of the preceding Claims, characterized in that the filament of polyester, polyamide, Polyurethane, polymethyl methacrylate or polycarbonate or depending on Requirement of another material, e.g. B. Viscose exists. Multilayer laminate material according to one of the preceding Claims, characterized in that the at least one fiber layer is made of carbon fibers, Glass fibers, aramid fibers or similar fibers is formed. Multilayer laminate material according to one of the preceding Claims, characterized by a matrix material, wherein the matrix material is a resin, and the multilayer laminate material is of the resin system type independently is. Multilayer laminate material according to one of the preceding Claims, characterized in that its thickness exceeds the number of alternating ones Layers can be determined. Multilayer laminate material according to one of the preceding Claims, characterized in that the thickness of the multilayer laminate material a knitted fabric can be increased by 0.2 to 0.5 mm. Multilayer laminate material according to one of the preceding Claims, characterized in that at least one of the outer layers a fiber layer is. Multilayer laminate material according to one of the preceding Claims, characterized in that the mesh size of the knitted fabric in a tensile or pressure load, z. B. at a breaking point, changeable is. Multilayer laminate material according to one of the preceding Claims, characterized in that the finished component in a temperature range between -40 ° C and + 250 ° C substantially without Power loss is usable. Multilayer laminate material according to one of the preceding Claims, characterized in that a prepreg can be produced therefrom. Use of the multilayer laminate material of the foregoing claims 1 to 14 in the field of aerospace, medical technology, the automotive industry, motorsport, mechanical engineering, for tuning parts or for Design elements.