Profiled stiffening element for load-bearing bending stiffening, vehicle and manufacturing process therefor

Abstract

The invention relates to a profiled stiffening element for load-bearing flexural stiffening on a flat fiber composite structure, wherein the stiffening element is formed from a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, has a profiled cross-sectional shape and extends in a longitudinal direction, characterized in that the stiffening element has an electrically conductive, metallic layer extending continuously in the longitudinal direction, wherein the stiffening element has at least two electrical contacts electrically connected to the electrically conductive layer.

Description

The invention relates to a profiled stiffening element for load-bearing bending stiffening on a planar fiber composite structure, wherein the stiffening element is formed from a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, has a profiled cross-sectional shape and extends in a longitudinal direction. The invention also relates to a vehicle with such stiffening elements.The invention also relates to a method for producing profiled reinforcing elements of this type and to a method for producing a vehicle.Due to the weight-specific strength and rigidity of fiber composite components which are produced from a fiber composite material, components of this type are no longer to be considered as being available from aerospace and from many other fields of application, such as the automobile sector. In the production of a fiber composite component, a matrix material embedding the fiber material is usually cured under the action of temperature and pressure and thus forms an integral unit with the fiber material after curing. The reinforcing fibers of the fiber material are thereby forced in their predetermined direction and can remove the loads occurring in the predetermined direction.Fiber composites from which such fiber composite components are produced generally have two main components, namely, on the one hand, a fiber material and, on the other hand, a matrix material. In addition to this, further secondary components can be used, such as binder materials or additional functional elements, which are to be integrated into the component.If dry fiber materials are provided for the production, the matrix material of the fiber composite material is infused into the fiber material during the production process by an infusion process, by means of which the dry fiber material is impregnated with the matrix material. This is generally effected on the basis of a pressure difference between the matrix material and the fiber material, for example by evacuating the fiber material by means of a vacuum pump. In contrast to this, fiber composites are also known in which the fiber material is already preimpregnated with the matrix material (so-called prepregs).Before the matrix material cures, the fiber material is generally introduced into a molding tool, which simulates the later component shape with its molding tool surface. In this case, both dry and prepreg fibre materials can be laid down or introduced into the mould. For the production of large-scale structural components, such as, for example, wing shells of commercial aircraft or rotor blades of wind turbines, automated fiber laying processes are used to optimize the laying process, in which a quasi-endless fiber material fed to the fiber laying head is laid on the tool with the aid of a production plant and at least one fiber laying head. In so-called fiber placement technology, preimpregnated fiber materials, for example, are deposited web-by-web on the molding tool with the aid of such a fiber laying head. The fiber laying head is arranged on a robot and can be moved or moved relative to the forming tool. As a result, the individual fiber webs can be laid down on the tool surface first web by web and then layer by layer. In the fiber placement technology, a plurality of, usually 8, 16 or 32, narrow material strips, so-called towns, are simultaneously deposited on the tool. In contrast to this, in the case of fiber tape laying technology, mostly wide fiber webs, also referred to as tapes (generally 150 mm, 300 mm or 600 mm wide with a thickness of a few tenths of a millimeter), are laid down on the molding tool with the aid of the fiber laying head.In addition to the mechanical strength and reduction of weight, the electrical interconnection or connection to various electrical systems plays an important role in the construction of vehicles, in particular aircraft or other aircraft and spacecraft, but also in the automobile sector and in a similar manner in the field of wind energy. The electronics in the vehicle include multiple devices, including peripheral devices. A closed circuit is required in each case for the electrical supply of the electrical devices. This can be realized on the one hand by a separate closed circuit for each individual electronic device. However, this requires a high outlay on material, costs and weight for the corresponding electrical lines. Especially in aircraft construction, the installation of the electrical interconnection is very complex in major component assembly (MCA) and in final assembly line (FAL), and thus leads to high costs.An alternative is to ground or return conductors of the electrical devices via a common circuit. The grounding can be effected, for example, via the connection of the electrical devices to metallic components of the vehicle, the electrical potential of which functions as ground.However, in the reduction of the weight of vehicles, increasingly fewer metallic components are used and instead increasingly fiber composites are used. However, these are generally not electrically conductive or only poorly electrically conductive and are therefore not suitable for grounding or for closing a circuit. Electrically conductive fiber composites are also only conditionally suitable for potential compensation between different devices and for lightning protection. Therefore, at present, for example in vehicle construction, in particular in aircraft construction, an electrical structural network (ESN) is constructed which consists of a plurality of individual parts and additional cables and ensures that the electronic devices are grounded or balanced and a closed circuit is provided. The electrical structure network can be a metallic frame which is integrated into the aircraft. The additional electrical structural network contributes to a higher weight and fuel consumption and also increases the costs and the outlay for vehicle construction and maintenance. In addition, many specially made components such as cables, cable lugs, insulation material and fixing elements are required, which introduce more weight into the aircraft and contribute to the high costs.The electrical structural network of a vehicle, for example of a road vehicle, aircraft or rail vehicle, also serves for the connection between individual control units and the peripheral devices or field devices installed distributed in the vehicle. Such peripheral devices can be used, for example. The actuators and / or sensors and devices for presenting information may be provided. With the increasing number of driver assistance systems, engine control devices and complex infotainment systems in the automobile industry, the complexity of the structural network also increases drastically, which leads to a significantly higher cabling outlay.Such an ESN must be installed in the assembly line in an aircraft in a complicated manner and is also unnecessarily heavy in terms of structurally lightweight vision, since these components are not involved in the load transfer. Such an additional weight in the aircraft is not inconsiderable.DE 10 2014 005 001 A1, DE 10 2014 213 881 A1 and DE 10 2013 101 801 A1 disclose body parts made of a fiber composite plastic in which conductor tracks or flat conductors are embedded between the individual fiber layers of the fiber material in order to thus impart current-carrying properties to the body parts. However, the disadvantage here is that additional materials have to be integrated into the body parts during the production process, which complicates the production and assembly process and moreover makes the body part heavier.US 2014 / 0097011 A1 discloses a fiber composite component which is formed from a conventional fiber material. Between the conventional fiber materials, a metal layer is provided which contains in particular an electrical conductor. This electrical conductor is used in addition to the other fiber materials, so that the actual composite component with the inner electrically conductive conductors is formed only when the component has also been correspondingly assembled in this way.WO 2012 / 004262 A2 likewise discloses a structure made of a fiber composite material, in which an additional electrical conductor is woven into the fiber material.It is therefore the object of the present invention to specify aspects of an improved electrical connection network (for example an electrical structure network), with which significant weight can be saved against the background of lightweight construction.The object is achieved according to the invention with the stiffening element according to claim 1, the vehicle according to claim 8 and the method for producing a stiffening element according to claim 12 and the method for producing a vehicle according to claim 15. Advantageous embodiments of the invention are then found in the corresponding dependent claims.According to claim 1, a profiled stiffening element of the generic type for load-bearing bending stiffening for vehicles is proposed, which stiffening element has at least one metallic layer extending continuously in the longitudinal direction and electrically conductive, wherein the stiffening element has at least two electrical contacts electrically connected to the electrically conductive layer.In other words, there is a continuous electrical connection between the at least two electrical contacts on account of the electrically conductive layer.This makes it possible to use profiled stiffening elements of this type, which serve for load-bearing bending stiffening on planar fiber composite structures, for the construction of an electrical connection network. In this case, the individual profiled stiffening elements, which are arranged on the planar fiber composite structure, are connected to one another via their contacts with corresponding intermediate connections, so that a complete electrical connection network (for example, is formed. The structure network) can be formed.Such a planar fiber composite structure of a vehicle can be, for example, outer cladding elements, body parts and / or body components of the vehicle. On this fiber composite structure, in particular in the interior, a plurality of such profiled stiffening elements are arranged, which can then be connected to one another to form an electrical connection network.With such profiled stiffening elements, an electrical structural network for a vehicle, in particular for an aircraft (commercial aircraft), can thus be realized without additional elements or metallic frames being required. The profiled stiffening elements are in any case required for stabilizing the fiber composite structure of the vehicle, so that no additional weight has to be introduced into the vehicle as a result.Vehicles within the meaning of the present invention are road, air, space and watercraft. In particular, vehicles within the meaning of the present invention are road, air, space and watercraft with an engine drive. In particular, vehicles within the meaning of the present invention are passenger cars, trucks, aircraft and other aircraft and spacecraft.Preferably, the stiffening element is made for the most part of its volume and its mass of non-conductive fiber composite material (for example. GRP) or poorly conductive fiber composite material (for example. CFRP). A volume proportion of less than 5%, in particular less than 2%, in particular less than 1%, is electrically conductive by the metallic layer.The material used for the electrically conductive, metallic layer is, in particular, aluminum, steel, stainless steel and / or copper. It can be provided here that the electrically conductive, metallic layer is covered with a protective and / or insulating layer or embedded therein, in order to protect it from corrosion, for example.In the context of the present invention, a stiffening element is thus understood to mean a load-bearing element of the vehicle. The stiffening element can have a curved structure, that is to say that it can be, for example, not straight in the longitudinal direction, but rather, for example, curved or curved. The stiffening element can be, for example, a stringer, spar or a frame.Profiled in the sense of the present invention is understood to mean that the cross section (transverse to the longitudinal axis) has a profiled shape and is not straight.Vehicle control devices in the sense of the present invention are understood to mean data processing units which are used for controlling and regulating systems relating to the vehicle. A vehicle control device means any signal processing device that serves a specific application or task purpose with respect to the vehicle. Such vehicle control devices can be used, for example. The control devices are used for controlling assistance systems, for controlling engine control and for controlling navigation and infotainment systems.Peripheral devices installed in the vehicle in the sense of the present invention are understood to mean in particular those components which are provided for the input or output of data and information. These can be done, for example. These may be sensors and / or actuators. As a rule, such peripheral devices or vehicle components are connected to the vehicle control devices, so that the peripheral devices make data available as input devices to the vehicle control device or output corresponding information as output devices or control corresponding actuators by means of actuators. Peripheral devices can accordingly be mechanical elements, such as, for example. These may be valves, but also lighting systems, monitors or any type of sensors.With the aid of such an electrical connection network (also called an electrical structural network in aircraft construction), which is formed from a multiplicity of profiled reinforcing elements connected to one another, the control units, peripheral devices and / or metallic components installed in the vehicle can be incorporated into the circuit. In this case, the electrical connection network made of the profiled stiffening elements functions in particular as a neutral conductor and / or protective conductor. It also serves as a potential compensation of devices and / or components connected to the electrical connection network and can also be used as lightning protection.According to the invention, it is thus proposed that the electrically conductive metallic layer is an integral component of the stiffening element. In particular, the electrically conductive layer is already included in the construction of the stiffening element with regard to the load-bearing function. This ensures that the stiffening element is electrically conductive and at the same time the weight of the stiffening element is as low as possible or is not increased.For the purposes of the present invention, an electrically conductive layer is understood to mean that the layer measures a maximum of 2 mm, in particular a maximum of 1 mm, in particular a maximum of 0.5 mm, along the height (thickness) which corresponds to the smallest direction of extension of the layer.The electrically conductive layer can be a metal foil, for example. The foil can consist, for example, of aluminum, brass, copper, steel, stainless steel, alloys of various metals or other metallic materials or semimetal materials.At least two contacts electrically connected to the metallic layer is understood in the sense of the present invention to mean that the stiffening element has at least two contacts spaced apart from one another, which are electrically conductive and which are electrically connected to the electrically conductive layer. Preferably, the at least two contacts have at least a distance of half the width of the stiffening element, preferably of at least half the length of the stiffening element, preferably of at least 90% of the length of the stiffening element.As a result, the electrically conductive layer can be electrically connected to further stiffening elements according to the invention, other vehicle elements and / or electrical devices such as vehicle control devices or peripheral devices, in particular by means of electrically conductive interconnects. For example, the contacts are metallic. For example, the contacts are designed as nails, screws, hooks, clamps, rivets or bolts. Intermediate connections can be cables, for example.As a result, it is possible to obtain an electrical structural network (ESN) of the vehicle by means of stiffening elements according to the invention and electrical interconnections between the stiffening elements. The advantages of the ESN formed in this way are that, compared to the known ESN embodiments, fewer individual parts, fewer structural outlay, assembly outlay, maintenance outlay and fewer costs and fewer weight are required, since a multiplicity of the electrically conductive elements of previously known ESNs are replaced by integrated electrically conductive layers in the reinforcing elements. In addition, the degree of automation during production is increased since the load-bearing vehicle structures are produced from the fiber composite material and the load-bearing vehicle structure inclusive of the electrically conductive layer can thus be produced in a single process step. The production of load-bearing vehicle structures with the aid of composite materials can be automated more strongly than the manual construction and the installation of additional electrical elements, depending on the specific application.It is thus proposed that the load-bearing vehicle structure, for example body-bearing structures such as, for example. Not only do spars, stringers, ribs or wing structures in aircraft, per se have the task of creating and holding the vehicle structure (shape and geometry), but at the same time are also electrically conductive, whereby the introduction of additional structures apart from the intermediate connections for the construction of the ESN is prevented. In other words, the load-bearing vehicle structure is at the same time also electrically conductive by the electrically conductive layer contained therein, as a result of which a separate cable harness for wiring and forming the on-board power supply system is replaced by the vehicle structure.It has been found here that the electrically conductive layer integrated into the composite material is suitable as a planar conductor for transmitting the electrical signals, working currents and / or supply voltage. In the form of surface conductors, the electrically conductive material layers can compensate for the increased electrical resistance in the case of otherwise quite small conductor cross sections, so that work can still be carried out with the correspondingly specified voltages of the vehicle control devices and vehicle components.According to one embodiment, it is provided that a predefined stiffness, minimum material thickness, strength and / or load bearing capacity of the stiffening element is obtained by the sum of the fiber composite material and the metallic layer.This means that the electrically conductive layer is an integral component when the predetermined stiffness, minimum material thickness, strength and / or load bearing capacity of the stiffening element is reached. Thus, the electrically conductive layer is required with regard to the material properties and the weight for achieving the predefined stiffness, minimum material thickness, strength and / or load bearing capacity of the stiffening element. In other words, the electrically conductive layer is necessary in order to achieve the predefined stiffness of minimum material strength, strength and / or load bearing capacity together with the fiber composite material.In the construction of vehicles such as aircraft, there are usually specifications for required minimum values in the rigidity, the minimum material thickness and the strength and in respect of the electrical load bearing capacity of either individual components or of component groups or of the entire vehicle.According to one embodiment, it is provided that the stiffening element is at least ten times as large as along a width and at least ten times as large as along a height in the longitudinal direction, in particular is at least fifty times as large as along the width and at least fifty times as large as along the height in the longitudinal direction.Thereby, a stiffening element is suitable to form part of a load-bearing vehicle structure. Examples of such stiffening elements are stringers, ribs and spars in aircraft. Elongated, profiled stiffening elements of this type are particularly suitable for absorbing bending loads.According to one embodiment, it is provided that the stiffening element has a profile along the width which has at least one bend and / or at least one angle of less than 88° or more than 92°, in particular at least two bends or angles of less than 88° or more than 92°, and / or that the cross section of the stiffening element has an omega shape, U shape, Z shape and / or I shape.By bending is meant that at least a portion of the profile is curved. For example, the bend can be a rounded edge, in particular so that the two straight sections adjoining the bend form an angle of less than 88° or more than 92° with respect to one another.Omega shape is understood to mean that the profile of the stiffening element is formed along the width in cross section like the Greek capital letter of the omega, that is to say that the profile has two horizontal sections at the same height, between which two sections are formed, which are each connected to one of the horizontal sections and which extend straight or obliquely vertically and meet a further horizontal section which connects the two vertical retaining sections to one another.The two horizontal sections, which are at the same height, can each comprise a further vertical or obliquely formed subsection at their edge, which is remote from the vertical holding sections, which subsection is preferably shorter than the holding sections and preferably extends in the same direction as the holding sections. The connection between the sections can be formed by means of angles or rounded, i.e. by means of bends.The term "U-shape" is understood to mean that the profile of the stiffening element along the width is designed in the same way as the Latin capital letter U in cross section. The curved region of the U can be formed, for example, in the shape of an arc, angular in the form of an open rectangle or like a rounded open rectangle.The stiffening element can have other profile shapes which are advantageous for load-bearing vehicle structural elements, in particular profile shapes which are known for stringers, spars or ribs of vehicles, for example of aircraft, for example a Z-shape or an I-shape.According to one embodiment, it is provided that the electrically conductive layer measures a thickness of at most 2 mm, preferably at most 1 mm, particularly preferably at most 0.5 mm.According to one embodiment, it is provided that the electrically conductive layer forms an outer surface of the stiffening element. Such an outer surface is also present if the electrically conductive layer is covered by a protective layer or embedded in such a protective layer. The electrically conductive layer preferably forms an outer surface whenever no further layers of fiber material are present in the direction of the outer side.A lower outer surface is in particular the surface with which the stiffening element is connected to the fiber composite structure. Opposite this is the upper outer surface. Advantageously, the electrically conductive layer is arranged on the upper and / or on the lower outer surface of the stiffening element. In this embodiment, the production of the stiffening element is particularly favorable. The electrically conductive layer can, however, also be arranged on a side surface.The object is also achieved according to the invention with the vehicle according to claim 8, wherein a plurality of profiled load-bearing stiffening elements are arranged on the fiber composite structure as described above, wherein at least two of these stiffening elements are connected to one another by means of an electrical intermediate connection via their respective electrical contacts in such a way that an electrical connection network is formed.The fiber composite structure is, for example, the vehicle structure, body or vehicle shell. The fiber composite structure can be formed from the same fiber composite material as the stiffening elements. The fiber composite structure can be completely or largely electrically insulating. The fiber composite structure can have partly or completely an electrically conductive layer which preferably makes up not more than 5% of the volume and / or not more than 10% of the weight of the fiber composite structure.The stiffening elements are preferably fixedly attached to the fiber composite structure, for example, bonded, soldered, bolted, screwed, nailed, riveted or otherwise fastened or joined.Within the meaning of the present invention, an electrical connection network is understood in particular to mean that electrical devices of the vehicle, for example vehicle control devices and peripheral devices for residual current recirculation, for lightning diversion, for electrostatic discharge and / or for diversion of induced signals, are connected to ground. Such an electrical connection network can be, for example, an electrical structural network (ESN) from aircraft construction.The stiffening elements are preferably connected to one another by means of electrical interconnections which are attached to the electrical contacts of the stiffening elements in such a way that the electrical devices of the vehicle are in each case grounded and any electrical potential differences, which also occur suddenly, are automatically dissipated rapidly.According to one embodiment, it is provided that the stiffening elements form a closed circuit together with the at least one electrical intermediate connection and at least one electrical device.It is particularly advantageous here if the electrically conductive layer of the stiffening elements forms the neutral conductor and / or protective conductor of the circuit.According to one specific embodiment, it is provided that at least one of the stiffening elements is connected to an electrical device of the vehicle, in particular to a vehicle control unit and / or a peripheral device.According to one embodiment, it is provided that the vehicle is an aircraft or spacecraft and the reinforcing elements are stringers, ribs and / or spars of the load-bearing aircraft structure and the fiber composite structure is the outer fuselage shell.A further aspect of the present invention is a method for producing a profiled stiffening element for vehicles for load-bearing bending stiffening on a planar fiber composite structure, comprising the steps: a) providing a fiber composite material which has a fiber material and a matrix material and an electrically conductive metallic layer, b) depositing fiber layers of the fiber material to form a fiber layer stack, c) wherein the electrically conductive metallic layer is deposited on the fiber layer stack or the fiber layer stack is deposited on the electrically conductive metallic layer, such that the electrically conductive metallic layer becomes an integral constituent part of the stiffening element, and d) arranging at least two electrical contacts on the electrically conductive metallic layer.The method can also comprise pressing the electrically conductive layer with the fiber layer stack. The method makes the electrically conductive layer an integral part of the stiffening element.In this case, the fiber material is preferably deposited on a molding tool having a molding tool surface, so that the profiled shape is thereby produced in cross section. The electrically conductive, metallic layer can form an outer surface of the stiffening element.It is conceivable that the metallic layer is first introduced into the mold, wherein the fiber layer stack is then subsequently formed on the fiber material. However, it is also conceivable for the fiber layer stack to be formed first in the molding tool, the metallic layer being introduced as the last layer.After the matrix material embedded in the fiber material has cured, resulting in a solid component with an integrated metallic layer, the electrical contacts are arranged on the metallic layer, for example by welding or electrically conductive adhesive bonding.A further aspect of the present invention is a method for producing a vehicle, comprising a) providing a fiber composite structure which is formed from a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, b) providing a plurality of profiled load-bearing stiffening elements as described above, c) arranging the profiled load-bearing stiffening elements on the fiber composite structure, and d) connecting the stiffening elements to one another by means of an electrical interconnection via their respective electrical contacts in such a way that an electrical connection network is formed.The electrically conductive network formed by the interconnections can finally be connected to a voltage source in order to thus form a ground connection or neutral conductor.The invention is explained in more detail by way of example with reference to the appended figures. The following are shown: FIG. 1 is a schematic, greatly simplified representation of a circuit diagram in a commercial aircraft made of fiber composite; FIG. 2 shows a schematic illustration of the production of the stiffening element according to the invention; FIG. 3 shows a representation of stringers and ribs on an aircraft fuselage; FIG. 4 shows an illustration of an electrical stringer-bulkhead connection; FIG. 5 shows a schematic illustration of a cross section through the fuselage of an aircraft with connection to aircraft-internal components.FIG. 1 shows a schematically greatly simplified illustration of a circuit diagram which is to be found in a modern commercial aircraft, for example in an A350. An electrical voltage source 10 supplies the power supply for an electrical switch box 11 and consumers 12.The aircraft to which this circuit diagram in FIG. 1 is applied is predominantly made of a fiber composite material, for example a CFRP (carbon fibers), with regard to the fuselage structure and the wing structure. The specific conductivity of carbon fibers is significantly lower than that of a metallic structure, such as aluminum. For this reason, in the prior art, in addition to the fiber composite structure 16 provided for the aircraft, an electrical structure network 15 is provided, which is additionally arranged on the load-bearing structure. However, this contributes to a significant increase in weight and conflicts with the concept of lightweight construction by using fiber composite materials.According to the invention, it is now provided that such an electrical structural network 15 is formed by existing elements of the fiber composite structure 16, so that an additional electrical structural network 15, as is known from the prior art, can be dispensed with.FIG. 2 shows the production of a profiled stiffening element 20 which is produced from a plurality of layers of fiber material 21. As in step a) for knowledge, a fiber layer stack is first produced from a fiber material 21, on which a metallic layer 22 is then applied. This fiber layer stack thus formed, comprising the fiber material 21 and the metallic layer 22, is subsequently cured in order to form the profiled stiffening element with a layer that is electrically conductive in the longitudinal direction.Subsequently, in step b), an electrical contact 23 is applied to the metallic layer 22, for example by welding, onto the profiled stiffening element 20 produced in this way. As a rule, at least two such electrical contacts 23 are applied to the metallic layer 22, so that there is an electrical connection from a first electrical contact 23 via the metallic layer 22 to a second electrical contact.Subsequently, in a third step c), the profiled stiffening element 20 produced in this way is applied to a fiber composite structure 25 to be stiffened and fastened there, for example by means of adhesive bonding (or else co-bonding, etc.). With the aid of an electrical interconnection 24, the metallic layer 22 can thus be connected to other reinforcing elements or components via the electrical contact 23.FIG. 3 shows a fiber composite structure 35 which can be, for example, the outer casing of an aircraft fuselage. The outer casing is reinforced on the inner side with ribs 36 and stringers 37 for load-bearing bending reinforcement. The ribs 36 extend in the circumferential direction, while the stringers 37 represent a longitudinal reinforcement. Both the ribs 36 and the stringer 37 are profiled reinforcing elements in the sense of the present invention and have a metallic layer which is provided on the upper, easily accessible side. The ribs 36 and the stringers 37 also have the corresponding electrical contacts.The electrical connection is shown in FIG. 4 between a frame 46 and stringer 47. The frame 46 has a metallic layer 46a which is connected to at least one electrical contact 46b. The stringer 47 likewise has an electrical layer 47 a, which is likewise contacted with at least one electrical contact 47 b. The electrical contact 46 bof the frame 46 is connected to the electrical contact 47 bof the stringer 47 by means of an electrical intermediate connection 44.Finally, FIG. 5 shows a part of a cross section through an aircraft fuselage 50 which has an electrical structure network 51 formed as described above. By means of intermediate connections 52, components of the aircraft which consist of metal, such as the rails 53 for the passenger seats, are thus connected to the electrical structural network 51 which is formed by the profiled reinforcing elements.List of reference characters10 Electrical voltage source 11 Electrical switchbox 12 Load 13 Neutral conductor / neutral conductor 14 Protective conductor 15 Electrical structure network 16 Fiber composite structure 20 Profiled stiffening element 21 Fiber material 22 Metallic layer 23 Electrical contact 24 Electrical interconnection 25 Fiber composite structure 35 Fiber composite structure 36 Frame 37 Stringer 44 Interconnection 46 Frame 46 aElectric layer of the frame 46 bElectric contact of the frame 47 Stringer 47 aElectric layer of the bumper 47 bElectric contact of the bumper 50 Aircraft fuselage 51 Electrical structure network of the aircraft fuselage 52 Interconnection 53 Metallic component of the aircraft fuselageReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2014 005 001 A1

[0012] DE 10 2014 213 881 A1

[0012] DE 10 2013 101 801 A1

[0012] US 2014 / 0097011 A1

[0013] WO 2012 / 004262 A2

[0014]

Claims

Profiled stiffening element for load-bearing bending stiffening on a planar fiber composite structure, wherein the stiffening element is formed from a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, has a profiled cross-sectional shape and extends in a longitudinal direction, characterized in that the stiffening element has an electrically conductive metallic layer extending continuously in the longitudinal direction, wherein the stiffening element has at least two electrical contacts electrically connected to the electrically conductive layer.Stiffening element according to Claim 1, characterized in that a predefined stiffness, minimum material thickness, strength and / or load-bearing capacity of the stiffening element is obtained by the sum of the fiber composite material and the metallic layer.Stiffening element according to one of the preceding claims, characterized in that the stiffening element is at least ten times as large as along a width and at least ten times as large as along a height in the longitudinal direction, in particular is at least fifty times as large as along the width and at least fifty times as large as along the height in the longitudinal direction.Stiffening element according to one of the preceding claims, characterized in that the stiffening element has a profile along the width which has at least one bend and / or at least one angle of less than 88° or more than 92°, in particular at least two bends or angles of less than 88° or more than 92°, and / or in that the cross section of the stiffening element has an omega shape, U shape, Z shape and / or I shape.Stiffening element according to one of the preceding claims, characterized in that the electrically conductive layer measures a thickness of not more than 2 mm, preferably not more than 1 mm, particularly preferably not more than 0.5 mm.Stiffening element according to one of the preceding claims, characterized in that the electrically conductive layer forms an outer surface of the stiffening element.Stiffening element according to one of the preceding claims, characterized in that the stiffening element is a stringer, a spar or a frame of an aircraft structure.Vehicle having a fibre composite structure which is formed from a fibre composite material having a fibre material and a matrix material embedding the fibre material, characterized in that a plurality of profiled load-bearing stiffening elements according to one of Claims 1 to 7 are arranged on the fibre composite structure, wherein at least two of these stiffening elements are connected to one another by means of an electrical intermediate connection via their respective electrical contacts in such a way that an electrical connection network is formed.Vehicle according to claim 8, characterised in that the stiffening elements form a closed circuit together with the at least one electrical intermediate connection and at least one electrical device.Vehicle according to Claim 8 or 9, characterized in that at least one of the reinforcing elements is connected to an electrical device of the vehicle, in particular to a vehicle control unit and / or a peripheral device.Vehicle according to one of Claims 8 to 10, characterized in that the vehicle is an aircraft or spacecraft and the reinforcing elements are stringers, ribs and / or spars of the load-bearing aircraft structure and the fibre composite structure is the outer fuselage shell.Method for producing a profiled stiffening element for vehicles for load-bearing bending stiffening on a planar fiber composite structure, comprising the steps: a) providing a fiber composite material which has a fiber material and a matrix material and an electrically conductive, metallic layer, b) depositing fiber layers of the fiber material to form a fiber layer stack, c) wherein the electrically conductive, metallic layer is deposited on the fiber layer stack or the fiber layer stack is deposited on the electrically conductive, metallic layer, such that the electrically conductive, metallic layer becomes an integral constituent part of the stiffening element, and d) arranging at least two electrical contacts on the electrically conductive, metallic layer.Method according to claim 12, characterised in that the electrically conductive metallic layer forms an outer surface of the stiffening element.Method according to claim 12 or 13, characterised in that the fibre material is deposited on a mould with a moulding tool surface which has an omega shape, U shape, Z shape and / or I shape.A method of manufacturing a vehicle comprising a) providing a fibre composite structure formed from a fibre composite comprising a fibre material and a matrix material embedding the fibre material, b) providing a plurality of profiled load-bearing stiffening elements according to any one of claims 1 to 7, c) arranging the profiled load-bearing stiffening elements on the fibre composite structure, and d) connecting the stiffening elements to each other by means of an electrical interconnection via their respective electrical contacts such that an electrical connection network is formed.

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