Belt structure for automated fiber placement (AFP) method, automated fiber placement apparatus and automated fiber placement (AFP) method

Abstract

A belt structure for an automatic fiber placement (AFP) method, an automatic fiber placement apparatus, and an automatic fiber placement (AFP) method. The present invention provides a belt structure (102) for use in an automatic fiber placement (AFP) method to manufacture a composite structure (100), the belt structure (102) comprising a first layer (111) and a second layer (112) connected to the first layer (111), the first layer (111) being configured as a support layer and the second layer (112) being configured as a pre-impregnated layer, where during or after the second layer (112) is laid onto the composite structure (110) to be manufactured, the pre-impregnated layer (112) is laid onto the composite structure (110) to be manufactured. The first layer (111) is removable from the second layer (112), an automatic fiber placement apparatus (130), an automatic fiber placement (AFP) method, and a composite structure (100) manufactured by such a method.

Description

TECHNICAL FIELD

[0001] The present invention relates to a tape construction for an automated fiber placement (AFP) method, an automated fiber placement apparatus and method. BACKGROUND

[0002] Although the invention can be used in many applications, the invention and the problem behind it will be explained in more detail in connection with an aircraft. However, the apparatus and method can equally be used for vehicles in all sectors of the transportation industry, such as road vehicles, rail vehicles or ships.

[0003] Large composite structures such as wings or fuselages of aircraft, but not limited to, are manufactured by automated fiber placement (AFP) methods. Therein, tapes, also called slits tapes, are used to build up a laminate structure comprising a plurality of layers of pre-impregnated fibers with a matrix. The tapes with a predetermined width can be derived from a wider sheet of pre-impregnated material. Slitting is used to ensure edge and width quality, preventing gaps or overlaps in the parallelly overlaid tapes during processing.

[0004] Automated fiber placement is commonly used for the manufacture of lightweight structures, in particular carbon fiber reinforced plastic (CFRP) tanks, which are more popular than aluminum tanks because they can improve the performance in cryogenic environments required for the storage of liquid hydrogen (LH2). The material used in such tank structures has a lower ply thickness, preferably less than 100 pm, instead of 125 to 250 pm of standard aerospace pre-impregnated materials. Since hydrogen has to be stored as a liquid at -253 °C to achieve a feasible volumetric energy density, in particular in aircraft, tanks with more different plies are prevented from micro-cracking in cryogenic environments.

[0005] Thinner plies or stacks are very sensitive in processing, since contact with the edges of the tapes can impair the edge quality and thus the overall tape width. For achieving the highest composite material performance, in particular in the above-mentioned cryogenic environments related to LH2 storage, laminate uniformity without undulations or gaps is of utmost importance. SUMMARY

[0006] Against this background, it is an object of the present invention to find a tape construction and manufacturing method which enables a high quality when processing processing-sensitive materials such as carbon fiber reinforced plastic (CFRP) and to ensure a high quality of laminates and structures manufactured from these materials.

[0007] This object is achieved by a tape construction for an automated fiber placement method having the features of claim 1, a fiber placement apparatus having the features of claim 7 and an automated fiber placement method according to claim 10.

[0008] According to a first aspect of the present invention, a tape structure for use in an automated fiber placement (AFP) process to manufacture a composite structure is provided. The tape structure comprises a first layer and a second layer connected to the first layer, wherein the first layer is configured as a support layer and the second layer is configured as a layer containing a matrix with fibers, preferably reinforcing fibers, embedded in the matrix. In the automated fiber placement (AFP) process, the first layer is configured to be removable from the second layer during or after the second layer is placed onto the composite structure to be manufactured. The tape structure has the advantage of allowing automated handling of a tape with a second layer having a layer thickness of less than 100 pm. In the tape structure, the first layer supports the second layer and prevents the second layer and the entire tape structure from curling, u-shaping and flipping over during processing. The first layer also reduces the warping of the second layer, especially when the tape structure is processed and handled on various spools in the automated fiber placement (AFP) equipment. The first layer also prevents width variations that occur due to tension applied to the second layer during unwinding and processing and ensures high edge quality in the second layer. Furthermore, the tape structure also allows handling of a tape structure comprising a second layer resulting from a tacky or sticky resin, as the first layer will separate the layers when the tape structure is wound on a spool. One advantage of the present invention is that it allows manufacturing of high quality laminates from thin layers with a single layer thickness preferably less than 100 pm with high edge quality, especially for cryogenic environments.

[0009] For the present invention, the first layer can consist of or comprise a polymer, preferably a polyester, a polyethylene or a polypropylene, but the present invention is not limited thereto. The second layer can preferably comprise reinforcing fibers, such as carbon fibers, embedded in an uncured thermoset matrix, preferably consisting of an epoxy resin, but the present invention is not limited thereto.

[0010] Another aspect of the invention is a fiber placement apparatus having a movable placement head for fiber placement in an automated fiber placement (AFP) process. The fiber placement apparatus comprises a laying device for placing and / or compacting a tape structure onto a composite structure or a front ply layer formed on the composite structure, a feeding device for feeding the tape structure by using a feeding member such as a transfer roll, a peeling device for grabbing the first ply and peeling the first ply from the tape structure second ply while or after placement and / or compaction, and a winding device for winding the peeled first ply. In the inventive apparatus, the feeding device, the peeling device and the winding device are positioned adjacent to the placement head and configured to move with the placement head and the tape structure during automated fiber placement. An advantage of this apparatus is that thin ply materials can be processed which are particularly suitable for cryogenic composite material tanks. Furthermore, with said apparatus, tape structures containing tacky or sticky resins in the second ply can be placed with higher precision and performance since the second ply is prevented from adhering to the roll or device by the first support ply. Since the feeding device, the peeling device for grabbing the first ply and peeling or tearing it from the second ply and the winding device are positioned in close proximity to the laying device for placing and / or compacting the tape structure, the first support ply is removed from the second ply before or even during or shortly after the second ply is placed onto the composite structure. This ensures dimensional stability of the placed second ply since warping, particularly of the second ply, is eliminated even when the tape structure is processed and handled on various spools in the automated fiber placement process and apparatus. This greatly reduces gaps and / or overlaps in the laminate which are known to cause undulations or resin rich zones which are prone to micro-cracking in the composite structure or laminate.

[0011] Another aspect of the present application is an automated fiber placement (AFP) method using the tape structure according to the present application, wherein the method comprises the following method steps: feeding the tape structure to a fiber placement device; placing the tape structure onto a composite structure or a pre-laminate layer formed on the composite structure by moving a fiber placement head over the composite structure or the pre-laminate layer formed on the composite structure; compacting the tape structure to establish a permanent connection between the second layer and the composite structure or the pre-laminate layer; peeling the first layer off the second layer before, during or after the placement and removing the first layer. This has the advantage that the second layer made of prepreg material and the first support layer made of backing material or foil having the exact width of the second layer are safely and accurately transferred to the placement position. The first support layer itself prevents significant gaps, undulations or width differences of the material during or after the placement. The first support layer is peeled off the second layer in a peeling device only at the end close to the placement onto the composite structure or the pre-laminate layer formed on the composite structure and not already in a spool holder, for example. Furthermore, the method is able to handle toughened and other matrix systems which usually have a high stickiness or tackiness and which easily clog the machine if not supported on a first layer or backing. It is also included that the placement head is positioned stationary and the composite structure is moved relative to the placement head.

[0012] Another aspect of the present application is a composite structure manufactured with the method according to the present application, wherein the composite structure is an aircraft component, in particular a tank structure for containing a liquid, preferably a liquid stored under cryogenic conditions such as liquid hydrogen (LH2). This has the advantage that due to the high strength / weight ratio, an aerospace composite material laminate can be manufactured, whereby the sensitivity to micro-cracks in the composite structure or laminate is reduced.

[0013] Advantageous embodiments and further developments are also evident from the further subclaims and from the description of the figures.

[0014] According to another aspect of the present application, the first layer is formed by a support backing or foil, preferably consisting of or comprising a polymer, preferably a polyester, a polyethylene or a polypropylene, the second layer comprises a thermoset matrix, the thermoset matrix consisting of an uncured thermoset polymer, the uncured thermoset polymer consisting of a mixture of a resin and a curing agent, optionally additives, and a plurality of fibers, preferably carbon fibers, embedded therein. This has the advantage that a slit tape layer with a thermoset matrix can be used which remains as thin as possible. Furthermore, the use of the tape structure with the first support layer also precisely maintains the edge quality of the tape, improving the overall structural quality of the laminate and / or composite structure produced therewith.

[0015] According to one embodiment of the present invention, the second layer comprises unidirectional pre-impregnated dry fibers. This has the advantage that material cracking in the manufactured composite structure is prevented, especially in low temperature environments or environments where the load bearing capacity needs to be extended and where cracks are easily formed and propagate.

[0016] According to another embodiment of the present invention, the second layer has a thickness of preferably less than 100 pm, in particular a thickness of less than 70 pm, preferably a thickness of between 30 pm and 80 pm. One advantage of the tape structure is that the first layer of the tape structure, which supports the second layer during handling up to lay-up, prevents the second layer from curling, u-shaping and flipping over. The first layer also prevents width variations in the second layer by eliminating tensile stresses applied to the second layer during feeding to the lay-up position on the composite structure, thereby achieving high laminate uniformity, without undulations or gaps, which is crucial to achieve the highest composite material performance.

[0017] According to another embodiment of the present invention, the second layer is positioned in the tape structure facing the structure to be manufactured during lay-up. This has the advantage that the first layer, i.e. the liner or foil, which is peeled off before the second layer is laid up and compressed on the composite structure or previous laminate, supports the second layer until it is laid up in the final position, thereby avoiding sticking to the compacting and lay-up devices and roller bars.

[0018] According to another embodiment of the present invention, the tape structure is provided on a spool. An advantage of the tape structure of the present invention is that the first layer prevents the layers of the tape from sticking together when the tape structure is wound onto the spool. This is particularly advantageous in tapes with a second layer having a thickness of less than 100 pm and a toughened or other matrix system with high adhesion. The first layer, configured as a liner or foil, also supports the unwinding of the tape before or during lay-up, preventing the tape from curling, u-shaping and / or flipping over and sticking during unwinding.

[0019] According to another embodiment of the present invention, the fiber placement device comprises a feeding device comprising a first spool carrying the tape structure, and a winding device comprising a second spool carrying the peeled-off first layer. This has the advantage that the tape structure can be unwound from the first spool, and the first layer can be peeled off and removed from the tape structure while the second layer is laid up on the composite structure or previous laminate, preventing interference with the lay-up process and the manufactured composite structure.

[0020] According to another embodiment of the present invention, the laying device comprises a compacting roller for establishing a permanent connection between the second layer and the composite structure or previous laminate formed on the composite structure. The compacting roller is configured to apply at least one of pressure, heat and electric current to the tape structure during or after lay-up. This has the advantage that lay-up efficiency is improved by preventing gaps and overlaps, which disturb laminate uniformity, in particular when thermoplastic or thermoset polymers are used as the matrix of the second layer, and the highest quality of the laminate is obtained.

[0021] According to another embodiment of the present application, a heating device is positioned adjacent to the deposition head, configured to apply heat to the tape structure before, during and / or after the deposition. The advantage of this implementation is that the application of heat can be concentrated to the deposition location, i.e. the zone where the connection between the second layer and the composite structure or the previous layer is established during the deposition. The use of a heating device positioned adjacent to the deposition head can improve the heat transfer efficiency, reducing the overall energy consumption of the device.

[0022] According to another embodiment, the method further comprises providing the tape structure by winding the tape structure on a first spool and winding the first layer on a second spool after the second layer is removed. The advantage of this implementation is that the first layer prevents the second layer from curling, warping, or turning or u-shaping while feeding the tape structure until the end of the deposition process. The first layer also prevents the second layer from sticking to the compaction roller or other parts of the equipment during the feeding and deposition. To avoid the first layer interfering with the composite structure after the deposition of the second layer, the second spool is immediately wound and the first layer is removed from the deposition zone after the deposition of the second layer is completed.

[0023] According to another embodiment, the method further comprises moving the fiber deposition head on the composite structure or the previous layer pressure layer in a direction forming an angle with the edge of the composite structure or the previous layer pressure layer. The advantage of this implementation is that, with the advantages of the deposition method and the tape structure, it is possible to deposit the second layer of the tape structure at different angles to achieve quasi-isotropy of the anisotropic fiber direction performance in the manufactured composite structure.

[0024] According to another embodiment, the method further comprises applying at least one of pressure, heat and electric current to the tape structure before, during or after the deposition. The advantage of this implementation is that the deposition efficiency is improved by preventing gaps and overlaps that would disturb the uniformity of the laminate, especially when a thermoplastic or thermoset polymer is used as the matrix of the second layer. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be described in more detail with reference to the following exemplary embodiments depicted in the attached drawings.

[0026] Figure 1a 、 1b , 1c schematically depicts a view of a tape without a structure according to an embodiment of the present application;

[0027] Figure 2 schematically depicts a view of a tape structure according to an embodiment of the present application;

[0028] Figure 3 schematically depicts an embodiment of a deposition device of the present application; and

[0029] Figure 4 schematically depicts a perspective view of a composite structure during manufacturing according to another embodiment of the present application. DETAILED DESCRIPTION

[0030] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. Other embodiments of the present invention and many of the intended advantages of the present invention will be readily apparent as they become better understood with reference to the detailed description. The elements in the drawings are not necessarily drawn to scale relative to each other. In the drawings, unless otherwise indicated, like reference numerals represent similar or functionally similar components.

[0031] Although specific embodiments are shown and described herein, it will be appreciated by those skilled in the art that various alternatives and / or equivalent embodiments may be substituted for the specific embodiments shown and described without departing from the scope of the invention. In general, this application is intended to encompass any modifications or variations of the specific embodiments discussed herein.

[0032] In the drawings, unless otherwise specified, the same elements, features, and components having the same function and the same effect are each given the same reference numeral.

[0033] Figure 1a 、 1b 1c depicts cut sections of tapes 103a, 103b, 103c used in an automated fiber placement method without providing a tape structure 102 according to the present invention. As shown in the figure, if the tapes 103a, 103b, 103c are processed and handled in an automated fiber placement (AFP) device 130 on various reels 104a, 104b or over long distances, the thin layers or tape materials configured as thin layer slit tapes with a layer thickness of preferably less than 100 μm are cut during processing. Figure 1a Shown tends to curl and flip.

[0034] The strips 103a, 103b, 103c with thinner layers are very sensitive to processing and are prone to damage to the layer edges 105, which significantly affects the quality of the edges 105 and thus the quality of the entire strip 103a, 103b, 103c. Figure 1b and 1cAs shown, during the laying of the tapes 103a, 103b, 103c, the edges 105 can change in size or width, resulting in undulations or gaps. This will reduce the uniformity of the overall laminate 101. However, the uniformity of the laminate 101 is essential to achieve the highest composite material performance, especially in cryogenic environments such as storage and handling of liquid hydrogen (LH2). In contrast to standard prepreg materials, the tapes 103a, 103b, 103c (also referred to as slit tapes) used for manufacturing the LH2 tank 120 structure have a smaller ply thickness of preferably less than 100 pm, instead of a ply thickness of 125 to 250 pm. Using multiple plies 112 laid in a staggered configuration, micro-cracks in the cryogenic environment are prevented.

[0035] Figure 2 A cross-section of a tape structure 102 according to an embodiment of the present application is schematically depicted. The tape structure 102 can be used in an automated fiber placement (AFP) process to manufacture a multi-layer composite structure 100. The tape structure 102 comprises a first layer 111 and a second layer 112, wherein the second layer 112 is placed on the first layer 111, the first layer 111 adhering to the second layer 122 during handling and storage of the tape structure 102, in particular during handling and storage on a spool 104a. The first layer 111 is configured as a support layer made of a backing or foil, preferably composed of or comprising a polymer, preferably a polyester, a polyethylene or a polypropylene, and the second layer 112 is configured as a prepreg layer containing a thermoset matrix 106 composed of an uncured thermoset polymer or epoxy resin comprising a mixture of resin and curing agent, optionally additives, into which a plurality of fibers 107, preferably carbon fibers, are embedded. The fibers 107 are provided in the form of unidirectional dry fibers 107. The first layer 111 can be removed from the second layer 122 during or after laying of the second layer 112 on the composite structure 100 manufactured in an automated fiber placement (AFP) process. Figure 2The tape structure 102 allows for automated processing of thin slit tape layers in the second layer 112 having a layer thickness of less than 100 μιη. The first layer 111 supports the second layer 112, preventing the tape structure 102 from curling, u-forming and flipping over during processing. The first layer 111 remains bonded to the second layer 112 during feeding of the tape structure 102 to the lay-up area 201 at the time of manufacture, which reduces warping of the tape structure 102, especially when the tape structure is processed and handled on various spools 104a, 104b in the automated fiber placement (AFP) machine 130. The first layer 111 also prevents width variations and damage to the tape edges 105 that occur due to tension applied to the second layer 112 during unwinding and processing, thereby improving the overall composite structure 100 quality. In addition, the tape structure 102 also allows for handling of slit tape created by tacky or sticky resins, as the first layer 111 separates the second layer 112 when the tape structure 102 is wound on the spools 104a, 104b, also preventing the second layer 112 from sticking to the roller bars. Furthermore, the tape structure 102 supported by the first layer 111 also protects the edge quality of the second layer 112.

[0036] Figure 3 An embodiment of the automated fiber placement machine 130 of the present application is schematically depicted. Figure 3 A manufacturing process of the composite structure 100 comprising a plurality of pre-impregnated material layers 112 stacked one on top of the other is also schematically depicted. As a basis, a mold or tool 109 defining the final structure and geometry of the composite structure 100 is used. The pre-impregnated material layers 112 are laid up onto the tool 109 to manufacture the final composite structure 100. Laying up a plurality of slit tape layers 112 will increase the thickness of the composite structure 100 until the final configuration is obtained. In Figure 3 In the present embodiment, the tape structure 102 of the present application is used, which comprises a first layer 111 and a second layer 112 wound on a first spool 104a. The tape structure 102 has a predetermined width, which can be selected for example in the range from 1 / 8 inch (3.175 mm) to ½ inch (12.7 mm). The tape structure 102 is typically provided in the form of a slit tape made from a wider pre-impregnated ply 101 or structure. The tape structure 102 comprises the first layer 111 and the second layer 112. The first layer 111 provides support to the second layer 112 when the tape structure 102 is wound stored on the first spool 104a, and further during feeding of the tape structure 102 from the first spool to the lay-up area 201 in the automated fiber placement (AFP) machine 130 for layer placement. Figure 3The layup head 200 is only schematically depicted by focusing on a layup device 202 comprising a compaction roller 203. Another device attached to or positioned in the vicinity of the compaction roller 203 is a peeling device (not shown) which ensures that the two layers 111, 112 of the tape structure 102 are separated shortly before or during the layup of the second layer 112 onto the tool 109 or a previously formed prepreg layer 112 in the composite structure 100 by grabbing the first layer 111 and peeling or tearing it off from the second layer 112 attached to the composite structure 100. In the peeling device, the first layer 111 of the tape structure 102 is removed by peeling it off from the second layer 112 while passing the peeling device. The tape structure 102 in a double layer configuration is fed to the layup head 200 with the second prepreg layer 112 facing the composite structure 100 or the tool 109. After layup, the second layer 112 is adhered to the preceding layer 112 or the composite structure 100, while the first layer 111 supporting the second layer 12 during feeding is removed and wound onto a second spool 104b attached to the layup head 200 or the automated fiber placement device 130.

[0037] The first layer 111 is provided in the form of a backing or foil, while the second layer 112 comprises a thermoset matrix 106 composed of an uncured thermoset polymer into which a plurality of fibers 107 are embedded. The uncured thermoset polymer comprises a mixture of resin and curing agent and optionally additional additives, the embedded fibers 107 used are unidirectional pre-impregnated dry fibers 107 such as carbon fibers. The second layer 112 has a thickness of preferably less than 100 pm, in particular less than 70 pm, preferably between 30 pm and 80 pm, so that it is easily warped or curled. As Figure 3The shown automated fiber placement machine 130 further comprises a heater 204 positioned in close proximity to the placement zone 201 of the second layer 112. The application of heat enhances the connection between the newly fed layer 112 and the previously laid layer 112 in the composite structure 100. As an alternative or second heat source, the compaction roller 203 can be configured as a heated roller. The compaction roller 203 applies pressure to the tape structure 102 while moving over the composite structure 100, thus pressing the newly laid layer 112 against the previous layer, establishing a connection between these layers 112. The tape structure 102 is continuously fed into the compaction zone 205 underneath the compaction roller 203 and remains in the manufactured composite structure 100, while the first layer 111 is removed or peeled off the second layer 112 and wound onto the second spool 104b. The first layer 111 not only stabilizes the very thin pre-preg material of the second layer 112, but also prevents the second layer 112 from adhering to the compaction roller 203 or the cover layer on the first spool 104a. Furthermore, the first layer 111 prevents the tape structure 102 from adhering to other devices in the placement head 200 that come into contact with the tape structure 102 during feeding and handling. Since the thinner laid or layers 112 are very sensitive in processing, especially in the edge zone, every contact with the tape edge 105 affects the edge quality, thus the entire tape width, which can lead to gaps in the laminate 101 of the composite structure 100. The tape structure 102 supports achieving laminate uniformity without undulations or gaps, thus achieving the highest composite performance.

[0038] Figure 3 The placement head 200 can be moved together with the tape structure 102 comprising the first layer 111 and the second layer 112 during fiber 107 or layer 112 placement and is configured to move over the previous laid layer 112 or the composite structure 100 in a direction that forms an angle with the edge zone 110 of the previous laid layer 112 or the composite structure 100. By laying the second layer 112 at different angles, quasi-isotropy of the anisotropic fiber directional performance is achieved. Thus, by preventing gaps and overlaps that would disturb the uniformity of the laminate 101, the placement efficiency is improved and the highest quality of the laminate 101 is achieved.

[0039] Figure 4 A perspective view of a composite structure 100 manufactured during manufacturing with a method according to an embodiment of the present application is schematically depicted. In this embodiment, the composite structure 100 is configured as a tank 120 having a cylindrical geometry, but is not limited thereto. The tank 120 is in some cases used for storing liquid hydrogen (LH2) under cryogenic conditions and is composed of a composite material or laminate, especially when used in the aircraft industry due to weight reduction requirements. Due to the high strength-to-weight ratio, the composite material or laminate 101 is preferably used for aviation purposes. As Figure 4As shown, the composite structure 100 configured as an aircraft tank 120 is manufactured using an automated fiber placement method to achieve the highest manufacturing quality and to meet specific requirements regarding leak protection. The multiple layers 112 used in the manufacture of the tank 120 form a composite material comprising a special resin and fibers 107 and are manufactured in a specific placement method to withstand low temperatures. The tapes are placed at different angles in order to achieve quasi-isotropy of the anisotropic fiber directional properties.

[0040] During the manufacture, the placement head 200 of the automated fiber placement device 130 moves together with the tape structure 102 comprising the first layer 111 and the second layer 112 over the tank 120 and places the second layer 112 of the tape structure 102. The tape structure 102 comprising unidirectional pre-impregnated fibers 107 is placed at different angles with respect to the preceding layer or tape. The tape structure 102 used here has a structure comprising two layers 111, 112. The first layer 111 forming a support layer is configured as a backing or foil covering the surface of the second layer 112 or is provided in the form of such a backing or foil. The tape structure 102 is provided in a spool 104a (not shown) and is fed to the placement head 200 while moving over the tank 120. In the placement head 200, a stripping device is provided which removes the first layer 111 before, during or shortly after the placement of the second layer 112 onto the tank 120.

[0041] The second layer 112 comprises a thermoplastic or uncured thermoset polymer matrix 106 provided in a mixture with a resin and a curing agent, facing the tank 120. Since the material of the matrix 106 is very viscous and difficult to handle in automated processing, the first support layer 111 significantly improves the manufacturing efficiency by supporting the second layer 112 during the feeding and by preventing it from adhering to the devices of the placement head 200 or the automated fiber placement device 130.

[0042] To prevent the material from cracking in low-temperature environments, the thickness of the second layer 112 is less than 100 pm. Since these tapes are prone to curling, warping or buckling if not supported during processing, the end of the tape structure 102 is fed to the placement head 200 and the first layer 111 is held in place until the second layer 112 is compressed onto the composite structure 100 and / or the preceding layer 112. During processing, the first layer 111 also guarantees the edge quality of the second layer 112.

[0043] Figure 4The shown tape structure 102 has a tape width of, for example, ½ inch (12.7 mm). The second layer 112 of the laminate 101 forming the composite structure 100 follows a precision of, for example, ±1%, thus achieving the highest quality laminate 101. The use of the placement head 200 moving over the composite can 120 avoids the gaps and overlaps of the second layer 112 of the laminate uniformity that would otherwise be disturbed. The can 120 manufactured as previously described has a laminate 101 uniformity without undulations or gaps, which is critical to achieve the highest composite performance, especially in cryogenic environments, such as in the storage of LH2.

[0044] After the tape placement is completed, the composite can 120 is cured under autoclave conditions at temperatures between 100 and 200°C to achieve a high final laminate quality. As Figure 4 The shown placement head 200 can also be used to manufacture other composite structures, such as pipes and pumping devices.

[0045] In the foregoing detailed description, various features are grouped together in one or more examples for the purpose of streamlining the disclosure. This description is intended to be illustrative, and not restrictive. It is intended to encompass all alternatives, modifications, and equivalents. Many other examples will suggest themselves to those of ordinary skill in the art having the benefit of this disclosure. These embodiments have been chosen and described in order to best explain the principles of the application and its practical applications to thereby enable others skilled in the art to best utilize the application and various embodiments with various modifications as are suited to the particular use contemplated.

[0046] List of Reference Signs

[0047] 100 composite structure

[0048] 101 laminate

[0049] 102 tape structure

[0050] 103a, 103b, 103c tape

[0051] 104a, 104b spool

[0052] 105 edge

[0053] 106 matrix

[0054] 107 fibers

[0055] 109 tool

[0056] 110 edge zone

[0057] 111 first layer

[0058] 112 second layer

[0059] 120 can

[0060] 130 automated fiber placement apparatus

[0061] 200 placement head

[0062] 201 placement zone

[0063] 202 layup device

[0064] 203 compaction roller

[0065] 204 heater

[0066] 205 compaction zone

Claims

1. A tape structure (102) for use in an automated fiber placement (AFP) method to manufacture a composite structure (100), the tape structure (102) comprising a first layer (111) and a second layer (112) connected to the first layer (111), the first layer (111) configured as a support layer and the second layer (112) configured as a prepreg layer, wherein, The first layer (111) can be removed from the second layer (112) during or after the second layer (112) is laid onto the composite structure (100) to be manufactured.

2. The tape structure (102) of claim 1, wherein, The first layer (111) is formed by a support mat or foil, preferably consisting of or comprising a polymer, preferably a polyester, a polyethylene or a polypropylene; the second layer (112) comprises a thermoset matrix (106) consisting of an uncured thermoset polymer comprising a mixture of a resin and a curing agent and optionally additives, and a plurality of fibers (107), preferably carbon fibers, embedded therein.

3. The tape structure of claim 1 or 2, wherein, The second layer (112) comprises unidirectional pre-impregnated dry fibers (107).

4. The tape structure of any one of claims 1 to 3, wherein, The second layer (112) has a thickness of preferably less than 100 pm, in particular less than 70 pm, preferably between 30 pm and 80 pm.

5. The tape structure (102) according to any one of claims 1 to 4, wherein, The second layer (112) is positioned in the tape structure (102) facing the composite structure (100) to be manufactured during laying.

6. The tape structure (102) according to any one of claims 1 to 5, wherein, The tape structure (102) is provided on a spool (104a, 104b).

7. An automated fiber placement apparatus (130) having a movable placement head (200) for fiber (107) placement in an automated fiber placement (AFP) method, comprising: - a feeding device for feeding the tape structure (102) according to any one of claims 1 to 6 to a placement zone (201), - a laying device for laying and / or compacting the tape structure (102) onto a composite structure (100) or a preceding ply (112) formed on the composite structure (100), - a peeling device for peeling the first layer (111) from the second layer (112) while or after laying and / or compacting, and - a winding device for winding the peeled first layer (111), wherein the feeding device, the peeling device and the winding device are positioned adjacent to the placement head (200) and are configured to move with the placement head (200).

8. The automated fiber placement apparatus (130) of claim 7, wherein, The feeding device comprises a first spool (104a) carrying the tape structure (102), the winding device comprises a second spool (104b) for winding the peeled first layer (111).

9. The automated fiber placement apparatus (130) according to claim 7 or 8, wherein, The laying device comprises a compacting roller (203) for establishing a permanent connection between the second layer (112) and the composite structure (100) or the preceding ply (112) formed on the composite structure (100), the compacting roller (203) being configured to apply at least one of a pressure, heat and an electric current to the tape structure (102) and / or the second layer (112) during or after laying.

10. The automated fiber placement apparatus (130) according to any one of claims 7 to 9, wherein, The automated fiber placement apparatus comprises a heating device (204) positioned adjacent to the placement head (200) configured to apply heat to the tape structure (102) before, during and / or after laying.

11. An automated fiber placement (AFP) method using the tape structure (102) according to any one of claims 1 to 6, wherein, The automated fiber placement method comprises feeding a tape structure (102) to an automated fiber placement device (130), placing the tape structure (102) onto a composite structure (100) or a pre-laminate layer (112) formed on the composite structure (100) by moving a placement head (200) over the composite structure (100) or the pre-laminate layer (112), compacting the tape structure (102) to establish a permanent connection between the second layer (112) and the composite structure (100) or the pre-laminate layer (112), peeling the first layer (111) from the second layer (112) while placing or after placing and removing the first layer (111).

12. The automated fiber placement method of claim 11, wherein, The automated fiber placement method further comprises providing the tape structure (102) by winding the tape structure on a first spool (104a) and winding the first layer (111) on a second spool (104b) after removing the first layer (111) from the tape structure (102).

13. The automated fiber placement method of claim 11 or 12, wherein, Moving the placement head (200) comprises moving the placement head (200) over the pre-laminate layer (112) or the composite structure (100) in a direction forming an angle with an edge zone (110) of the pre-laminate layer (112) or the composite structure (100).

14. The automated fiber placement method of any of claims 11-13, wherein, Applying at least one of pressure, heat and electric current to the tape structure (102) before, during or after placing.

15. A composite structure (100) manufactured with the automated fiber placement method according to any one of claims 11 to 14, wherein, The composite structure (100) is an aircraft component, in particular a tank (120) structure containing a liquid, preferably a cryogenic storage liquid such as liquid hydrogen (LH2).

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