DE102018209935A1 - Composite structure for a vehicle, vehicle with the composite structure and method for producing the composite structure - Google Patents

Abstract

The invention relates to a composite structure (1) for a vehicle (2), comprising a fiber-reinforced plastic area with a woven fiber section that is embedded in a plastic matrix, the woven fiber section comprising first fiber strands (3) in a warp direction and second fiber strands (4) in a weft direction, the warp direction being transverse to the weft direction, at least one functional fiber (5) running parallel to and between the first fiber strands (3) in the warp direction and / or at least parallel to and between the second fiber strands (4) in the weft direction a functional fiber (5) runs, the at least one functional fiber (5) having a different material composition than the fibers of the first fiber strands (3) and the second fiber strands (4). The invention further relates to a vehicle (2) with a composite structure (1) according to the invention and a method for producing a composite structure (1) according to the invention.

Description

The present invention relates to a composite structure for a vehicle, comprising a fiber-reinforced plastic area with a woven fiber section which is embedded in a plastic matrix, the woven fiber section having first fiber strands in a first fiber direction and second fiber strands in a second fiber direction, the first fiber direction being transverse runs to the second fiber direction. The invention further relates to a vehicle with such a composite structure and a method for producing such a composite structure.

Various composite structures for vehicle construction are known in the prior art. Carbon fiber reinforced plastics (CFRP) are now particularly widespread, particularly in the luxury segment and / or in the sports car sector. On the one hand, these can be installed on the vehicle for visual reasons in order to differ from conventional vehicles. On the other hand, CFRP components are also used as functional components in order to achieve the highest possible strength and / or temperature resistance, for example with the lowest possible weight.

CFRP components usually consist of carbon fibers embedded in a matrix made of synthetic resin. The mechanical properties of the cured composite benefit above all from the tensile strength and rigidity of the carbon fibers. The matrix prevents the fibers from moving against each other under load. To do this, the matrix must adhere to the fiber, otherwise the components may fail.

The strength and rigidity of CFRP components are significantly higher in the direction of the fibers than transverse to the direction of the fibers. The strength across the fiber is lower than with an unreinforced matrix. For this reason, individual fiber layers or fiber strands are laid in different directions. This can be done in a weaving or braiding process.

Carbon fibers have a significantly lower density than materials such as steel. Depending on the type of fiber, their weight-specific stiffness in the direction of the fiber can be higher than that of steel. In this way, a particularly rigid component assembly can be produced, which is particularly suitable for applications with a directed main loading direction, in which a low mass and high rigidity are important.

Nonetheless, fiber composite components for different applications have to be designed to be more voluminous in order to withstand the same forces as a corresponding metal component, as a result of which the weight advantage is reduced. In addition, a component made of CFRP has relatively brittle fracture properties.

The object of the present invention is to at least partially take into account the problems described above. In particular, it is an object of the present invention to provide a correspondingly improved composite structure, a vehicle with such a composite structure and a method for producing such a composite structure for a vehicle.

The above object is achieved by a composite structure with the features of claim 1 and by a vehicle with the features according to claim 8 and a method with the features according to claim 9. Further features and details of the invention result from the subclaims, the description and the drawings , Features and details that are described in connection with the composite structure apply, of course, also in connection with the vehicle according to the invention, the method according to the invention and vice versa, so that with respect to the disclosure of the individual aspects of the invention, reference can always be made to one another.

According to a first aspect of the present invention, a composite structure for a vehicle is provided. The composite structure has a fiber-reinforced plastic region with a woven fiber section which is embedded in a plastic matrix, the woven fiber section having first fiber strands in a warp direction and second fiber strands in a weft direction and the warp direction being transverse to the weft direction. At least one functional fiber runs parallel to and between the first fiber strands in the warp direction and / or parallel to and between the second fiber strands in the weft direction, the at least one functional fiber having a different material composition than the fibers of the first fiber strands and the second fiber strands.

In extensive tests within the scope of the present invention, it was found that with the help of specifically positioned functional fibers or functional fiber sections, a significant increase in the function of the composite structure can be achieved. In other words, it deviated from the conventional type of generic composite structures and integrated the at least one functional fiber into a new type of composite structure. The at least one functional fiber can be understood to mean a plurality of functional fibers provided separately from one another and / or a functional fiber which has a plurality of functional fiber sections running parallel to one another.

Depending on the desired function and / or the desired field of application of the composite structure, the desired effects can be achieved in a simple and inexpensive manner with at least one suitable functional fiber.

The at least one functional fiber is to be understood in particular as a wire-shaped fiber element, which preferably consists of a predefined material composition, by means of which the desired function can be achieved.

The fiber-reinforced plastic area is to be understood as an area of the composite structure in which a fiber-reinforced fabric section is designed. Embedding in the plastic matrix is to be understood as reinforcement by the plastic matrix, in that the plastic matrix at least partially encompasses the woven fiber section and / or is positively connected to it.

The warp direction is transverse, in particular orthogonal or at least substantially orthogonal to the weft direction. The at least one functional fiber runs parallel or at least substantially parallel to and between the first fiber strands in the warp direction and / or parallel or at least substantially parallel to and between the second fiber strands in the weft direction.

The arrangement of the functional fiber parallel to and between the first and / or second fiber strands is understood to mean that the at least one functional fiber is sandwich-like at least at one point, preferably at several points, between two fiber strands, that is to say between two first fiber strands or between two second fiber strands is arranged, wherein the at least one functional fiber does not have to touch the respective fiber strands between which it runs parallel or essentially parallel. In an advantageous embodiment variant, fiber strands and functional fibers are always arranged alternately in the weft direction and / or in the warp direction.

In principle, it can also be sufficient or even advantageous from a manufacturing point of view to arrange the functional fiber only in the warp direction or the weft direction.

In addition to the arrangement of the functional fiber described above, it is also possible to position the functional fiber directly within at least one fiber strand in the warp direction and / or in the weft direction, that is to say within at least one first fiber strand and / or within at least one second fiber strand. In this case, the at least one functional fiber can be integrated almost invisibly into the composite structure.

A fiber strand can be understood to mean a fiber bundle, that is to say a bundle with several fibers. The fiber strand can have a round, elliptical or rectangular cross section.

According to a further embodiment of the present invention, it is possible for the fibers of the first fiber strands and of the second fiber strands to be carbon fibers in a composite structure. In this case, the composite structure in the basic structure is a known CFRP component or a corresponding CFRP structure, which, however, is supplemented by the at least one functional fiber according to the invention, and which one, if applicable, on selected fiber strands was waived or this was replaced by a functional fiber. Such a CFRP component, as described above, can be supplemented with additional advantageous functions in a simple and inexpensive manner by means of the at least one functional fiber.

It can be particularly advantageous here if the at least one functional fiber of a composite structure according to the invention has at least one metal fiber and / or at least one glass fiber. The electrical conductivity of the composite structure can be specifically improved or produced by the at least one metal fiber. With the aid of the at least one metal fiber and / or the at least one glass fiber, the composite structure can accordingly be used in areas in which it has not previously been possible to use. Steel fibers, in particular stainless steel fibers, have proven to be particularly suitable metal fibers. Steel or stainless steel fibers can be used to specifically improve fracture properties with regard to the ductility and / or the strength of the composite structure. Furthermore, it is possible that a noble metal fiber, for example at least one silver fiber and / or at least one gold fiber, is used as the at least one metal fiber. The at least one precious metal fiber is particularly corrosion-resistant.

It can be a further advantage if the at least one metal fiber or functional fiber is coated in a composite structure according to the present invention. Extensive tests within the scope of the present invention have shown that, with a view to corrosion protection, it is more favorable for certain applications of the composite structure to use at least one coated functional fiber instead of a high-quality functional fiber in the form of at least one stainless steel fiber and / or noble metal fiber. In this case, the at least one functional fiber can be configured, for example, as at least one lacquered copper fiber. The paint can be in the form of a Corrosion protection lacquer and / or an insulating lacquer for electrical insulation of the at least one functional fiber can be configured.

Furthermore, it is possible that in a composite structure according to the invention the at least one functional fiber runs between each first fiber strand and / or between every second fiber strand. In other words, the composite structure has a plurality of functional fibers or functional fiber sections, the first fiber strands and the functional fibers in the warp direction, and / or the second fiber strands and the functional fibers in the weft direction, in each case alternately arranged parallel to one another, preferably spaced apart from one another. In tests within the scope of the present invention, this structure has proven to be a particularly advantageous compromise in terms of weight, cost and the desired function of the functional fibers or functional fiber sections.

In a composite structure according to a further embodiment variant of the present invention, the at least one functional fiber runs only in the warp direction. Such a composite structure can be produced particularly easily and inexpensively. It has been shown that a placement of the at least one functional fiber exclusively in the warp direction can nevertheless be sufficient to achieve the desired properties in the composite structure. When using the composite structure, it may only be necessary to pay attention to whether it is stressed more in the warp direction or in the weft direction, since the composite structure subsequently has different functional properties in the warp direction than in the weft direction.

In the case of a composite structure according to the present invention, it is also possible for the composite structure to have a layer structure with a cover layer and functional layers underneath, the at least one functional fiber running exclusively in the cover layer. It has been shown that it is sufficient for the presently desired functional improvements in the composite structure with regard to fracture properties, strength and / or electrical conductivity if the at least one functional fiber runs exclusively in the cover layer of the composite structure. This enables the desired functional influencing of the composite structure to be implemented relatively inexpensively. The lower functional layers of the composite structure can comprise biax fabrics, knitted fabrics and / or other material compositions and / or layers.

According to a further aspect of the present invention, a vehicle is provided with a composite structure as described in detail above, at least part of the body and / or a fitting of the vehicle having such a composite structure. A vehicle according to the invention thus brings with it the same advantages as have been described in detail with reference to the composite structure according to the invention. The vehicle is preferably designed in the form of a motor vehicle, in particular in the form of a car or truck. However, the invention is not limited to road vehicles. The vehicle can also be understood to mean an aircraft, a watercraft, a rail vehicle or a robot.

• - Bereitstellen der ersten Faserstränge,
• - Bereitstellen der zweiten Faserstränge,
• - Bereitstellen der wenigstens einen Funktionsfaser,
• - Verweben der ersten Faserstränge, der zweiten Faserstränge und der wenigstens einen Funktionsfaser zum gewebten Faserabschnitt, in welchem die wenigstens eine Funktionsfaser parallel zu und zwischen den ersten Fasersträngen in Kettrichtung und/oder parallel zu und zwischen den zweiten Fasersträngen in Schussrichtung verläuft, und
• - Einbetten des Faserabschnitts in eine Kunststoffmatrix zum Herstellen der Verbundstruktur.

According to yet another aspect of the present invention, a method for producing a composite structure as described above is provided. The process has the following steps:

• Provision of the first fiber strands,
• Provision of the second fiber strands,
• Providing the at least one functional fiber,
• - weaving the first fiber strands, the second fiber strands and the at least one functional fiber into the woven fiber section, in which the at least one functional fiber runs parallel to and between the first fiber strands in the warp direction and / or parallel to and between the second fiber strands in the weft direction, and
• - Embedding the fiber section in a plastic matrix to produce the composite structure.

A method according to the invention thus also brings with it the advantages described above. In a method according to the invention, fibers, for example carbon fibers, for providing the first fiber strands and the second fiber strands can each be provided on a winding spool and a functional fiber on a further winding spool. The fibers or carbon fibers and the functional fiber can now first be applied to a warp beam and then woven together to produce the composite structure. According to an alternative embodiment variant, the intermediate step for providing the fibers on the warp beam can also be dispensed with.

In the present case, the fiber section is preferably embedded in the plastic matrix in an RTM or wet pressing process. A composite structure according to the invention with a high manufacturing quality and a correspondingly high component quality can be realized by these types of processes.

Further measures improving the invention result from the following description of various exemplary embodiments of the invention, which are shown schematically in the figures. All of the features and / or advantages arising from the claims, the description or the figures, including structural details and spatial arrangements, can be essential to the invention both individually and in the various combinations.

• 1 eine Draufsicht auf einen Ausschnitt aus einer Verbundstruktur gemäß einer erfindungsgemäßen Ausführungsform,
• 2 eine Draufsicht auf einen Ausschnitt aus einer im Stand der Technik bekannten Verbundstruktur,
• 3 eine Seitenansicht auf eine Verbundstruktur gemäß einer Ausführungsform der vorliegenden Erfindung,
• 4 eine Draufsicht auf ein Fahrzeug mit einer Verbundstruktur gemäß einer Ausführungsform der vorliegenden Erfindung, und
• 5 ein Flussdiagramm zum Erläutern eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung.

Each shows schematically:

• 1 2 shows a plan view of a section of a composite structure according to an embodiment of the invention,
• 2 3 shows a plan view of a section of a composite structure known in the prior art,
• 3 2 shows a side view of a composite structure according to an embodiment of the present invention,
• 4 4 is a top view of a vehicle with a composite structure in accordance with an embodiment of the present invention; and
• 5 a flowchart for explaining a method according to an embodiment of the present invention.

Elements with the same function and mode of action are in the 1 to 5 each provided with the same reference numerals.

1 schematically shows a composite structure 1 for a vehicle 2 according to a first embodiment. The composite structure 1 has a fiber-reinforced plastic area with a woven fiber section which is embedded in a plastic matrix. The woven fiber section has first fiber strands 3 in one weft direction and second fiber strands 4 in a warp direction, the warp direction being transverse, more precisely orthogonal to the weft direction.

Parallel to and in the warp direction between the first fiber strands 3 Functional fibers run in the warp direction 5 or corresponding functional fiber sections. More precisely, the functional fibers run 5 alternating with the first fiber strands 3 , Between the second fiber strands 4 run in the weft direction, viewed in the weft direction, no functional fibers 5 ,

The first fiber strands 3 and the second fiber strands 4 each have carbon fibers and are provided in the form of a CFRP composite. The functional fibers 5 are provided in the form of noble ray fibers or noble ray wires. Alternatively, lacquered copper fibers and / or precious metal fibers could also be used.

In 2 is for comparison the in 1 composite structure shown 1 a composite structure known in the prior art 1' shown. As in 2 recognizes this composite structure 1' no functional fibers 5 on.

3 shows a schematic side view of the in 1 composite structure shown 1 , The composite structure shown 1 has a layer structure with a top layer 1a and underlying functional layers 1b . 1c . 1d . 1e on, with the functional fibers 5 only in the top layer 1a run. The functional layers 1b . 1c . 1d . 1e have different biax fabrics, knitted fabrics, etc. depending on the application.

In 4 is a vehicle 2 with the in 1 composite structure shown 1 shown. It should be noted that the composite structure 1 in 4 for better visibility of the functional fibers 5 is shown relatively coarse and does not correspond to the reality in which the composite structure 1 is provided much smaller. In the in 4 shown preferred embodiment, the vehicle roof has the composite structure in question 1 on or is partially formed from this.

Regarding 5 is then a method of manufacturing the composite structure described above 1 explained. This will be done in a first step S1 first the first fiber strands 3 and the second fiber strands 4 each provided on a winding spool. In a second step S2 becomes the functional fiber 5 provided on a winding spool. The steps S1 and S2 can of course also be carried out in a different order or simultaneously.

Are the fiber strands 3 . 4 and the functional fiber 5 are provided in a third step S3 to one like in 1 shown, woven fiber section connected, in which the at least one functional fiber 5 viewed in the warp direction parallel to and between the first fiber strands 3 runs in the warp direction. The fiber section is then in a fourth step S4 to manufacture the composite structure 1 embedded in a plastic matrix. The fiber section is embedded in the plastic matrix in an RTM or wet pressing process.

In addition to the illustrated embodiments, the invention permits further design principles. That is, the invention should not be considered limited to the embodiments shown in the figures.

LIST OF REFERENCE NUMBERS

1

composite structure

1'

composite structure

1a

topcoat

1b

functional layer

1c

functional layer

1d

functional layer

1e

functional layer

2

vehicle

3

first fiber strands

4

second fiber strands

5

functional fiber

Claims (10)

Composite structure (1) for a vehicle (2), comprising a fiber-reinforced plastic area with a woven fiber section that is embedded in a plastic matrix, the woven fiber section having first fiber strands (3) in a warp direction and second fiber strands (4) in a weft direction, the warp direction being transverse to the weft direction, characterized in that at least one functional fiber (5) runs parallel to and between the first fiber strands (3) in the warp direction and / or that at least one functional fiber runs parallel to and between the second fiber strands (4) in the weft direction (5) runs, the at least one functional fiber (5) having a different material composition than the fibers of the first fiber strands (3) and the second fiber strands (4). Composite structure (1) Claim 1 , characterized in that the fibers of the first fiber strands (3) and the second fiber strands (4) are carbon fibers. Composite structure (1) according to one of the preceding claims, characterized in that the at least one functional fiber (5) has at least one metal fiber and / or at least one glass fiber. Composite structure (1) Claim 3 , characterized in that the at least one metal fiber is painted. Composite structure (1) according to one of the preceding claims, characterized in that the at least one functional fiber (5) runs between each first fiber strand (3) and / or between every second fiber strand (4). Composite structure (1) according to one of the preceding claims, characterized in that the at least one functional fiber (5) runs only in the warp direction. Composite structure (1) according to one of the preceding claims, characterized in that the composite structure has a layer structure with a cover layer (1a) and underlying functional layers (1b, 1c, 1d, 1e), the at least one functional fiber (5) only in the Cover layer (1a) runs. Vehicle (2) with a composite structure (1) according to one of the preceding claims, wherein at least part of the body and / or a fitting of the vehicle (2) has the composite structure (1). Method for producing a composite structure (1) according to one of the Claims 1 to 7 , comprising the steps: - providing the first fiber strands (3), - providing the second fiber strands (4), - providing the at least one functional fiber (5), - weaving the first fiber strands (3), the second fiber strands (4) and the at least one functional fiber (5) for the woven fiber section, in which the at least one functional fiber (5) runs parallel to and between the first fiber strands (3) in the warp direction and / or parallel to and between the second fiber strands (4) in the weft direction, and - Embedding the fiber section in a plastic matrix to produce the composite structure (1). Procedure according to Claim 9 , characterized in that the embedding of the fiber section in the plastic matrix is carried out in an RTM or wet pressing process.

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