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

Abstract

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.

Description

[0001] The invention relates to a profiled stiffening element for load-bearing bending stiffening of 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.

[0002] The invention also relates to a method for manufacturing such profiled stiffening elements and a method for manufacturing a vehicle.

[0003] Due to the high strength-to-weight ratio and stiffness of fiber-reinforced composite components, these components are now indispensable in the aerospace industry and many other fields, such as the automotive sector. In the production of a fiber-reinforced composite component, a matrix material embedding the fiber material is typically cured under temperature and pressure, forming an integral unit with the fiber material after curing. This forces the reinforcing fibers of the fiber material into their predetermined orientation, enabling them to transfer the applied loads in the specified direction.

[0004] Fiber-reinforced composite materials, from which such fiber-reinforced composite components are manufactured, generally have two main components: a fiber material and a matrix material. In addition, further secondary components can be used, such as binder materials or additional functional elements that are to be integrated into the component.

[0005] If dry fiber materials are used for production, the matrix material of the fiber composite is infused into the fiber material during the manufacturing process, thereby impregnating the dry fiber material with the matrix material. This typically occurs due to a pressure difference between the matrix material and the fiber material, for example, by evacuating the fiber material using a vacuum pump. In contrast, fiber composites are also known in which the fiber material is already pre-impregnated with the matrix material (so-called prepregs).

[0006] Before the matrix material hardens, the fiber material is typically placed in a mold whose surface replicates the final component shape. Both dry and pre-impregnated fiber materials can be deposited or introduced into the mold. For the production of large-scale structural components, such as wing skins for commercial aircraft or rotor blades for wind turbines, automated fiber placement processes are used to optimize the process. These processes utilize a production system and at least one fiber placement head to deposit a virtually continuous stream of fiber material onto the mold. In this so-called fiber placement technology, for example, pre-impregnated fiber materials are deposited onto the mold in webs using such a fiber placement head.The fiber placement head is mounted on a robot and can be moved relative to the mold. This allows the individual fiber webs to be laid onto the mold surface, first web by web and then layer by layer. In fiber placement technology, several narrow strips of material, usually 8, 16, or 32, called tows, are laid onto the mold simultaneously. In contrast, fiber tape laying technology typically uses the fiber placement head to lay wide fiber webs, also called tapes (usually 150 mm, 300 mm, or 600 mm wide with a thickness of a few tenths of a millimeter), onto the mold.

[0007] Besides mechanical strength and weight reduction, electrical networking and connection to various electrical systems play a crucial role in the design of vehicles, especially aircraft and other aerospace vehicles, but also in the automotive sector and similarly in the wind energy sector. Vehicle electronics comprise several devices, including peripherals. Each of these devices requires a closed circuit to supply power. This can be achieved by using a dedicated closed circuit for each individual electronic device. However, this requires significant material, cost, and weight for the necessary electrical wiring. Particularly in aircraft manufacturing, the installation of electrical networking in Major Component Assembly (MCA) and Final Assembly Line (FAL) is highly complex and therefore leads to high costs.

[0008] An alternative is to ground or connect the electrical devices via a common circuit. Grounding can be achieved, for example, by connecting the electrical devices to metallic components of the vehicle, whose electrical potential acts as ground.

[0009] However, in the effort to reduce vehicle weight, fewer metallic components are being used, and fiber-reinforced composites are increasingly being employed instead. These materials are generally not electrically conductive or only poorly conductive and therefore unsuitable for grounding or closing an electrical circuit. Electrically conductive fiber-reinforced composites are also only conditionally suitable for equipotential bonding between different devices and for lightning protection. Therefore, in vehicle manufacturing, particularly in aircraft construction, an electrical structural network (ESN) is currently being designed. This ESN consists of numerous individual components and additional cables and provides grounding or equipotential bonding for electronic devices and ensures a closed electrical circuit. The electrical structural network can be a metallic frame integrated into the aircraft.The additional electrical structural network contributes to increased weight and fuel consumption, and also raises the costs and effort involved in vehicle construction and maintenance. Furthermore, many custom-made components such as cables, cable lugs, insulation material, and fixing elements are required, adding weight to the aircraft and contributing to the high costs.

[0010] The electrical network of a vehicle, such as a road vehicle, aircraft, or rail vehicle, also serves to connect individual control units with the peripheral devices or field devices distributed throughout the vehicle. These peripheral devices can include actuators and / or sensors, as well as devices for displaying information. With the increasing number of driver assistance systems, engine control units, and complex infotainment systems in the automotive industry, the complexity of the network also increases dramatically, leading to a significantly higher wiring effort.

[0011] Such an ESN requires complex assembly on the aircraft's assembly line and is also unnecessarily heavy from a structural lightweighting perspective, as these components do not contribute to load bearing. This additional weight in the aircraft is therefore not insignificant.

[0012] From DE 10 2014 005 001 A1, DE 10 2014 213 881 A1 and DE 10 2013 101 801 A1, body parts made of a fiber-reinforced plastic are known in which conductive tracks or flat conductors are embedded between the individual fiber layers of the fiber material to give the body parts electrically conductive properties. A disadvantage of this, however, is that additional materials must be integrated into the body parts during the manufacturing process, which complicates both the manufacturing and assembly process and also makes the body part heavier.

[0013] US patent 2014 / 0097011 A1 discloses a fiber composite component formed from a conventional fiber material. A metal layer, containing an electrical conductor, is sandwiched between the conventional fiber materials. This electrical conductor is used in addition to the other fiber materials, so that the actual composite component with the internal electrically conductive conductors is only formed when the component has been assembled accordingly.

[0014] WO 2012 / 004 262 A1 also describes a structure made of a fiber composite material in which an additional electrical conductor is woven into the fiber material.

[0015] From DE 10 2016 117 903 A1, a body part arrangement for a motor vehicle is known, wherein at least one electrical conductor is integrated into the body part by embedding the electrical conductor in a plastic part and the plastic part becoming part of the body part.

[0016] It is therefore an object of the present invention to specify aspects of an improved electrical connection network (e.g. an electrical structural network) with which significant weight savings can be achieved in the context of lightweight construction.

[0017] The problem is solved according to the invention by means of the stiffening element according to claim 1, the vehicle according to claim 8, the method for manufacturing a stiffening element according to claim 12, and the method for manufacturing a vehicle according to claim 15. Advantageous embodiments of the invention are then found in the corresponding dependent claims.

[0018] According to claim 1, a generic profiled stiffening element for load-bearing bending stiffening of vehicles is proposed, which has at least one continuously extending and electrically conductive metallic layer, wherein the stiffening element has at least two electrical contacts electrically connected to the electrically conductive layer.

[0019] In other words, there is a continuous electrical connection between the at least two electrical contacts due to the electrically conductive layer.

[0020] This makes it possible to use such profiled stiffening elements, which serve for load-bearing bending stiffening on planar fiber composite structures, to construct an electrical connection network. The individual profiled stiffening elements, arranged on the planar fiber composite structure, are connected to each other via their contacts with corresponding intermediate connections, thus forming a complete electrical connection network (e.g., structural network).

[0021] Such a planar fiber composite structure of a vehicle can, for example, consist of exterior trim elements, body panels, and / or fuselage components. Within this fiber composite structure, a multitude of such profiled stiffening elements are arranged, particularly on the interior, which can then be interconnected to form an electrical network.

[0022] With such profiled stiffening elements, an electrical structural network for a vehicle, especially for an aircraft (commercial aircraft), can be realized without the need for additional elements or metallic frames. The profiled stiffening elements are required anyway to stabilize the vehicle's fiber composite structure, so no additional weight needs to be added to the vehicle.

[0023] Vehicles within the meaning of the present invention are road vehicles, aircraft, spacecraft, and watercraft. In particular, vehicles within the meaning of the present invention are road vehicles, aircraft, spacecraft, and watercraft with an engine. Specifically, vehicles within the meaning of the present invention are passenger cars, trucks, airplanes, and other aircraft and spacecraft.

[0024] Preferably, the stiffening element is formed for the majority of its volume and mass from non-conductive fiber-reinforced composite material (e.g., GFRP) or low-conductivity fiber-reinforced composite material (e.g., CFRP). A volume fraction of less than 5%, in particular less than 2%, and in particular less than 1%, is electrically conductive due to the metallic layer.

[0025] The electrically conductive metallic layer is typically made of aluminum, steel, stainless steel, and / or copper. It may be designed so that the electrically conductive metallic layer is covered with or embedded in a protective and / or insulating layer, for example, to protect it from corrosion.

[0026] A stiffening element within the meaning of the present invention is thus understood to be a load-bearing element of the vehicle. The stiffening element may have a curved structure, meaning that, for example, it may not be straight in the longitudinal direction, but rather arc-shaped or curved. The stiffening element may, for example, be a stringer, spar, or frame.

[0027] In the context of the present invention, "profiled" means that the cross-section (perpendicular to the longitudinal axis) has a profiled shape and is not straight.

[0028] Vehicle control units within the meaning of the present invention are understood to be data processing units used for controlling and regulating systems relating to the vehicle. A vehicle control unit is any signal processing device that serves a specific purpose or function in relation to the vehicle. Such vehicle control units can, for example, be used to control driver assistance systems, engine control, and navigation and infotainment systems.

[0029] For the purposes of the present invention, peripheral devices installed in a vehicle are understood to be, in particular, those components designed for the input or output of data and information. These can be, for example, sensors and / or actuators. Such peripheral devices or vehicle components are generally connected to the vehicle control units, so that the peripheral devices, as input devices, provide data to the vehicle control unit, or, as output devices, output corresponding information or, by means of actuators, control corresponding actuators. Peripheral devices can therefore be mechanical elements, such as valves, but also lighting systems, monitors, or any type of sensor.

[0030] Using such an electrical connection network (also called an electrical structural network in aircraft construction), which consists of numerous interconnected profiled stiffening elements, the control units, peripheral devices, and / or metallic components installed in the vehicle can be integrated into the electrical circuit. The electrical connection network made up of the profiled stiffening elements functions primarily as a neutral conductor and / or protective conductor. It also serves as equipotential bonding for devices and / or components connected to the electrical connection network and can additionally be used as lightning protection.

[0031] According to the invention, it is therefore proposed that the electrically conductive metallic layer be an integral part of the stiffening element. In particular, the electrically conductive layer is already taken into account in the design of the stiffening element with regard to its load-bearing function. This ensures that the stiffening element is electrically conductive while simultaneously keeping its weight as low as possible or not increasing it at all.

[0032] For the purposes of the present invention, an electrically conductive layer is understood to be one in which the layer measures a maximum of 2 mm along the height (thickness) corresponding to the least direction of expansion of the layer, in particular a maximum of 1 mm, and in particular a maximum of 0.5 mm.

[0033] The electrically conductive layer can be, for example, a metal foil. The foil can be made of materials such as aluminum, brass, copper, steel, stainless steel, alloys of various metals, or other metallic or semi-metallic materials.

[0034] For the purposes of the present invention, "at least two contacts electrically connected to the metallic layer" means that the stiffening element has at least two spaced-apart contacts which are electrically conductive and which are electrically connected to the electrically conductive layer. Preferably, the at least two contacts are spaced at least half the width of the stiffening element, more preferably at least half the length of the stiffening element, and more preferably at least 90% of the length of the stiffening element.

[0035] This allows the electrically conductive layer to be electrically connected to other stiffening elements according to the invention, other vehicle components, and / or electrical devices such as vehicle control units or peripheral devices, in particular by means of electrically conductive intermediate connections. For example, the contacts are metallic. For example, the contacts are designed as nails, screws, hooks, clamps, rivets, or bolts. Intermediate connections can be, for example, cables.

[0036] This makes it possible to obtain an electrical structural network (ESN) of the vehicle using stiffening elements according to the invention and electrical connections between the stiffening elements. The advantages of the ESN thus formed are that, compared to known ESN designs, fewer individual parts, less design effort, assembly effort, maintenance effort, and lower costs and weight are required, since a large number of the electrically conductive elements of previous ESNs are replaced by integrated electrically conductive layers in the stiffening elements. Furthermore, the degree of automation in manufacturing is increased, since the load-bearing vehicle structures are manufactured from the fiber composite material, and thus the load-bearing vehicle structure, including the electrically conductive layer, can be produced in a single process step.Depending on the specific application, the production of load-bearing vehicle structures using composite materials can be automated to a greater extent than manual assembly and the installation of additional electrical elements.

[0037] It is therefore proposed that the load-bearing vehicle structure, e.g., body-supporting structures such as spars, stringers, frames, or wing structures in aircraft, should not only have the inherent function of creating and maintaining the vehicle structure (shape and geometry), but should also be electrically conductive. This would eliminate the need for additional structures, apart from intermediate connections, to build the ESN (Electrical Safety Network). In other words, the load-bearing vehicle structure is also electrically conductive due to the electrically conductive layer it contains, thus replacing the need for a separate wiring harness for the wiring and formation of the vehicle's electrical system.

[0038] It has been shown that the electrically conductive layer integrated into the composite material is suitable as a planar conductor for transmitting electrical signals, operating currents, and / or supply voltage. In the form of planar conductors, the electrically conductive material layers can compensate for the increased electrical resistance associated with otherwise relatively small conductor cross-sections, thus allowing continued operation with the specified voltages of the vehicle control units and vehicle components.

[0039] According to one embodiment, it is provided that a predetermined stiffness, minimum material thickness, strength and / or load-bearing capacity of the stiffening element results from the sum of the fiber composite material and the metallic layer.

[0040] This means that the electrically conductive layer is an integral component in achieving the specified stiffness, minimum material thickness, strength, and / or load-bearing capacity of the stiffening element. Therefore, the electrically conductive layer is necessary in terms of its material properties and weight to achieve the specified stiffness, minimum material thickness, strength, and / or load-bearing capacity of the stiffening element. In other words, the electrically conductive layer is required, together with the fiber-reinforced composite material, to achieve the specified stiffness, minimum material thickness, strength, and / or load-bearing capacity.

[0041] When designing vehicles such as aircraft, there are usually specifications for required minimum values ​​for stiffness, minimum material thickness and strength, as well as for the electrical load-bearing capacity of either individual components or groups of components or the entire vehicle.

[0042] According to one embodiment, the stiffening element is provided to be at least ten times larger in the longitudinal direction than along a width and at least ten times larger than along a height, in particular at least fifty times larger in the longitudinal direction than along the width and at least fifty times larger than along the height.

[0043] This makes a stiffening element suitable for forming part of a load-bearing vehicle structure. Examples of such stiffening elements are stringers, frames, and spars in aircraft. These elongated, profiled stiffening elements are particularly well-suited for transferring bending loads.

[0044] According to one embodiment, the stiffening element has a profile along its width that 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.

[0045] A bend is defined as a curved section of the profile. For example, the bend can be a rounded edge, in particular such that the two straight sections adjacent to the bend form an angle of less than 88° or more than 92° with each other.

[0046] The term Omega shape refers to the fact that the profile of the stiffening element is shaped along its width in cross-section like the Greek capital letter Omega, meaning that the profile has two horizontal sections at the same height, between which two sections are formed, each connected to one of the horizontal sections and extending straight or obliquely vertically and meeting another horizontal section that connects the two vertical support sections.

[0047] The two horizontal sections, located at the same height, can each include at their edge, facing away from the vertical support sections, a further vertical or inclined subsection, which is preferably shorter than the support sections and preferably extends in the same direction as the support sections. The connection between the sections can be formed by angles or rounded bends.

[0048] A U-shape refers to a stiffening element whose profile, along its width, resembles the capital letter U in cross-section. The curved portion of the U can be, for example, arc-shaped, angular (like an open rectangle), or rounded (like an open rectangle).

[0049] The stiffening element may have other profile shapes that are advantageous for load-bearing vehicle structural elements, in particular profile shapes known for stringers, spars or frames of vehicles, for example aircraft, e.g. a Z-shape or an I-shape.

[0050] According to one embodiment, the electrically conductive layer has a maximum thickness of 2 mm, preferably a maximum of 1 mm, and particularly preferably a maximum of 0.5 mm.

[0051] According to one embodiment, 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 or embedded in a protective layer. Preferably, the electrically conductive layer always forms an outer surface when no further layers of fiber material are present on the outer side.

[0052] The lower outer surface is, in particular, the surface to 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 lower outer surface of the stiffening element. In this embodiment, the manufacture of the stiffening element is particularly efficient. However, the electrically conductive layer can also be arranged on a side surface.

[0053] The problem is also solved according to the invention with the vehicle according to claim 8, wherein a plurality of profiled, load-bearing stiffening elements as described above are arranged on the fiber composite structure, wherein at least two of these stiffening elements are connected to each other by means of an electrical intermediate connection via their respective electrical contacts in such a way that an electrical connection network is formed.

[0054] The fiber composite structure is, for example, the vehicle structure, body, or vehicle shell. The fiber composite structure can be made of 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 a partially or completely electrically conductive layer, which preferably comprises a maximum of 5% of the volume and / or a maximum of 10% of the weight of the fiber composite structure.

[0055] The stiffening elements are preferably firmly attached to the fiber composite structure, for example by gluing, soldering, bolting, screwing, nailing, riveting or otherwise fastening or joining.

[0056] For the purposes of the present invention, an electrical connection network is understood to mean, in particular, that electrical devices of the vehicle, for example, vehicle control units and peripheral devices for fault current feedback, lightning protection, electrostatic discharge, and / or the dissipation of induced signals, are connected to an earthing system. Such an electrical connection network could, for example, be an electrical structural network (ESN) from aircraft construction.

[0057] The stiffening elements are preferably connected to each other by means of electrical intermediate connections which are attached to the electrical contacts of the stiffening elements, so that the electrical devices of the vehicle are each grounded and any electrical potential differences, even those occurring suddenly, are quickly dissipated automatically.

[0058] According to one embodiment, the stiffening elements, together with at least one electrical connection and at least one electrical device, form a closed circuit.

[0059] It is particularly advantageous if the electrically conductive layer of the stiffening elements forms the neutral conductor and / or protective conductor of the circuit.

[0060] According to one embodiment, 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.

[0061] According to one embodiment, the vehicle is an aircraft or spacecraft, and the stiffening elements are stringers, frames and / or spars of the load-bearing aircraft structure, and the fiber composite structure is the outer fuselage shell.

[0062] Another aspect of the present invention is a method for manufacturing a profiled stiffening element for vehicles for load-bearing bending stiffening on a planar fiber composite structure, comprising the steps of: a) Providing a fiber composite material comprising a fiber material and a matrix material as well as an electrically conductive metallic layer, b) Laying down layers of fiber material into a stack of fiber layers, c) wherein the electrically conductive metallic layer is deposited onto the fiber layer stack or the fiber layer stack is deposited onto the electrically conductive metallic layer, such that the electrically conductive metallic layer becomes an integral part of the stiffening element, and d) Arranging at least two electrical contacts on the electrically conductive metallic layer.

[0063] The process can also include pressing the electrically conductive layer together with the fiber layer stack. This process makes the electrically conductive layer an integral part of the stiffening element.

[0064] The fiber material is preferably deposited onto a forming tool with a shaping surface, thus creating the profiled shape in cross-section. The electrically conductive metallic layer can form an outer surface of the stiffening element.

[0065] It is conceivable that the metallic layer is first introduced into the mold, with the fiber layer stack then being formed on the fiber material. Alternatively, the fiber layer stack is first formed in the mold, with the metallic layer being added last.

[0066] After the matrix material embedded in the fiber material has hardened, creating a solid component with an integrated metallic layer, the electrical contacts are arranged on the metallic layer, for example by welding or electrically conductive bonding.

[0067] Another aspect of the present invention is a method for manufacturing a vehicle with a) Providing a fiber composite structure comprising a fiber composite material, 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 each other via an electrical connection through their respective electrical contacts in such a way that an electrical connection network is formed.

[0068] The electrically conductive network created by the intermediate connections can finally be connected to a voltage source to form a ground connection or neutral conductor.

[0069] The invention is explained in more detail using the attached figures as examples. They show: Fig. 1. Schematic, highly simplified representation of a circuit diagram in a fiber composite commercial aircraft; Fig. 2 Schematic representation of the manufacture of the stiffening element according to the invention; Fig. 3. Illustration of stringers and frames on an aircraft fuselage; Fig. 4. Illustration of an electrical stringer-frame connection; Fig. 5. Schematic representation of a cross-section through the fuselage of an aircraft with connection to internal aircraft components.

[0070] Fig. Figure 1 shows a highly simplified schematic diagram of a circuit diagram as found in a modern commercial aircraft, for example, an A350. An electrical voltage source 10 supplies power to an electrical switch box 11 and loads 12. The neutral conductor and, if applicable, the protective conductor 14 are electrically connected to an electrical network 15, which is fed back to the electrical voltage source 10.

[0071] The aircraft in which this electrical circuit diagram is located Fig. The aircraft, as used in this application, is primarily constructed from a fiber-reinforced composite material, such as CFRP (carbon fiber reinforced polymer), with regard to the fuselage and wing structures. 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-reinforced composite structure 16 intended for the aircraft, an electrical structural network 15 is provided, which is additionally arranged on the load-bearing structure. However, this contributes to a significant increase in weight and contradicts the concept of lightweight construction through the use of fiber-reinforced composite materials.

[0072] 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.

[0073] Fig. Figure 2 shows the production of a profiled stiffening element 20, which is made from several layers of fiber material 21. As described in step a), a stack of fiber layers is first produced from a fiber material 21, onto which a metallic layer 22 is then applied. Subsequently, this fiber layer stack formed from the fiber material 21 and the metallic layer 22 is cured to form the profiled stiffening element with a longitudinally electrically conductive layer.

[0074] Subsequently, in step b), an electrical contact 23 is applied to the metallic layer 22 of the profiled stiffening element 20 produced in this way, for example by welding. Typically, at least two such electrical contacts 23 are applied to the metallic layer 22, so that an electrical connection exists from a first electrical contact 23 across the metallic layer 22 to a second electrical contact.

[0075] 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 attached there, for example by gluing (or co-bonding, etc.). With the aid of an electrical connection 24, the metallic layer 22 can thus be connected to other stiffening elements or components via the electrical contact 23.

[0076] Fig. Figure 3 shows a fiber composite structure 35, which can, for example, be the outer shell of an aircraft fuselage. The outer shell is reinforced on the inside with frames 36 and stringers 37 for load-bearing bending stiffening. The frames 36 extend circumferentially, while the stringers 37 provide longitudinal stiffening. Both the frames 36 and the stringers 37 are profiled stiffening elements according to the present invention and have a metallic layer on their upper, easily accessible side. The frames 36 and the stringers 37 also have the corresponding electrical contacts.

[0077] The electrical connection is in Fig. Figure 4 shows the connection between a frame 46 and a stringer 47. The frame 46 has a metallic layer 46a which is connected to at least one electrical contact 46b. The stringer 47 also has an electrical layer 47a which is also connected to at least one electrical contact 47b. The electrical contact 46b of the frame 46 is connected to the electrical contact 47b of the stringer 47 by means of an electrical intermediate connection 44.

[0078] Fig. Figure 5 shows a portion of a cross-section through an aircraft fuselage 50, which has an electrical structural network 51 formed as described above. By means of intermediate connections 52, components of the aircraft made of metal, such as the rails 53 for the passenger seats, are connected to the electrical structural network 51 formed by the profiled stiffening elements. Reference symbol list 10 electrical voltage source 11 electrical switch box 12 consumers 13 Neutral conductor / neutral conductor 14 Protective conductor 15 electrical structural network 16 Fiber composite structure 20 profiled stiffening elements 21 Fiber material 22 metallic layer 23 electrical contact 24 electrical intermediate connections 25 Fiber composite structure 35 Fiber composite structure 36 frame 37 Stringers 44 Intermediate connection 46 frame 46a electrical layer of the frame 46b electrical contact of the frame 47 Stringers 47a electrical layer of the springer 47b electrical contact of the springer 50 aircraft fuselages 51 Electrical structural network of the aircraft fuselage 52 Intermediate connection 53 metallic component of the aircraft fuselage

Claims

[1] 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 by that the stiffening element has a continuous, electrically conductive metallic layer extending in the longitudinal direction, wherein the stiffening element has at least two electrical contacts electrically connected to the electrically conductive layer. [2] Stiffening element according to claim 1, characterized by , that a given stiffness, minimum material thickness, strength and / or load-bearing capacity of the stiffening element results from the sum of the fiber composite material and the metallic layer. [3] Stiffening element according to any of the preceding claims, characterized by that the stiffening element is at least ten times larger in the longitudinal direction than along a width and at least ten times larger than along a height. [4] Stiffening element according to any of the preceding claims, characterized by that the stiffening element has a profile along its width that has at least one bend and / or at least one angle 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. [5] Stiffening element according to any of the preceding claims, characterized by that the electrically conductive layer has a maximum thickness of 2 mm. [6] Stiffening element according to any of the preceding claims, characterized by that the electrically conductive layer forms an outer surface of the stiffening element. [7] Stiffening element according to any of the preceding claims, characterized bythat the stiffening element is a stringer, a spar or a frame of an aircraft structure. [8] Vehicle with a fiber composite structure comprising a fiber composite material, a fiber material and a matrix material embedding the fiber material, characterized by , that a plurality of profiled, load-bearing stiffening elements according to one of claims 1 to 7 are arranged on the fiber composite structure, wherein at least two of these stiffening elements are connected to each other by means of an electrical intermediate connection via their respective electrical contacts in such a way that an electrical connection network is formed. [9] Vehicle according to claim 8, characterized by that the stiffening elements together with the at least one electrical intermediate connection and at least one electrical device form a closed circuit. [10] Vehicle according to claim 8 or 9, characterized bythat at least one of the stiffening elements is connected to an electrical device of the vehicle. [11] Vehicle according to any one of claims 8 to 10, characterized by that the vehicle is an aircraft or spacecraft and the stiffening elements are stringers, frames and / or spars of the load-bearing aircraft structure and the composite fiber structure is the outer fuselage shell. [12] 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 comprising a fiber material and a matrix material as well as an electrically conductive metallic layer, b) Laying down layers of fiber material into a stack of fiber layers, c) wherein the electrically conductive metallic layer is deposited onto the fiber layer stack or the fiber layer stack is deposited onto the electrically conductive metallic layer, such that the electrically conductive metallic layer becomes an integral part of the stiffening element, and d) Arranging at least two electrical contacts on the electrically conductive metallic layer. [13] Method according to claim 12, characterized by , that the electrically conductive metallic layer forms an outer surface of the stiffening element. [14] Method according to claim 12 or 13, characterized by that the fiber material is placed on a forming tool with a shaping tool surface that has an Omega shape, U shape, Z shape and / or I shape. [15] Method for manufacturing a vehicle with a) Providing a fiber composite structure comprising a fiber composite material, a fiber material and a matrix material embedding the fiber 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 fiber composite structure, and d) Connecting the stiffening elements to each other via an electrical connection through their respective electrical contacts in such a way that an electrical connection network is formed.

Images