AEROSTRUCTURE

Abstract

Aerostructure. A composite wing box structure formed from reinforced thermoplastic. The composite includes carbon fiber reinforcement and a plurality of insulating elements to localize the heat generated during the structure's manufacturing process. The wing box manufacturing process includes the steps of interlacing a series of insulating elements into a plurality of sheets and consolidating the insulating elements and sheets to form a laminate. The laminate is then aligned with a support structure in such a way that the insulating elements overlap the support structure. The laminate is then fused to the support structure using a non-contact heating process, such as induction welding.

Description

/ 27 AEROSTRUCTURE Separated from BR112020022321-2, filed on 03 / 05 / 2019. Priority Claim.

[001] The present claim asserts priority for the Patent Application. U.S. Provisional Application No. 62 / 666,193 filed on May 3, 2018. The full disclosure of the application is hereby incorporated by reference. Field of invention

[002] The present invention relates to the field of composite materials. In particular, the present application relates to structures formed from multiple components made of composite materials. The present invention finds particular application in the field of aerostructures formed from multiple composite elements. Fundamentals

[003] Composite materials have been used in a wide variety of applications where the benefit of high-strength, low-weight materials outweighs the cost of the materials. For example, historically, aerostructures were formed from lightweight metals such as aluminum and, more recently, titanium. However, a substantial portion of modern aircraft is formed from composite materials. One material commonly used in the aerospace industry is carbon fiber reinforced thermosetting plastic. Complex structures can be formed from such materials, and once the structures cure, the shape becomes permanent. However, this advantage limits the ability to fuse the formed structure with a separate structure. Instead, the separate elements are connected using separate connectors, such as fasteners.Although structural elements made of reinforced thermoplastic material can be connected without separate fasteners, the process of fusing the elements requires heating the components above a temperature that can cause... Petition 870230087041, dated 02 / 10 / 2023, page 13 / 48 / 27 damage to the structure. Therefore, there is a need for an efficient process to connect structural composite components without causing damage to the components. Summary of the Invention

[004] In view of the foregoing, according to one aspect, the present invention provides a laminate structure that is configured to localize the heat produced during an induction welding process. In particular, the laminate is configured to localize the heat in a particular area of ​​a particular ply (or plies) of a multilayer carbon fiber reinforced thermoplastic composite laminate. According to one aspect, the heat is localized in a particular area of ​​a particular ply by incorporating multiple layers of insulating elements arranged in a pattern and embedded in the layers of the laminate. Optionally, the laminate can be incorporated into an aerostructure, such as a wing box.

[005] According to another aspect, the present invention provides a composite aerostructure having a plurality of longitudinally elongated stringers and ribs interconnected to form a grid, wherein each of the stringers and ribs comprises an upper element having a layer of one-way or woven carbon fiber reinforced thermoplastic material forming a weld zone. A composite coating is connected to the grid of stringers and ribs. The laminate includes at least five plies of carbon fiber reinforced thermoplastic material. In the first ply the carbon fibers are oriented in a first direction. In the second ply the carbon fibers are oriented in the first direction and the first ply overlaps and is directly connected to the second ply.The third layer has carbon fibers oriented in a second direction transverse to the first direction, and the fourth layer has carbon fibers oriented in the second direction, and the third layer overlaps and is directly connected to the fourth layer. The fifth layer has fibers of... Petition 870230087041, dated 02 / 10 / 2023, p. 14 / 48 / 27 carbon fibers oriented transversely to the carbon fibers in the upper elements of the stringers and ribs. The laminate also includes a plurality of elongated insulating elements formed of electrically insulating material. The insulating elements each have a length and a width, and at least a plurality of the insulating elements have a length that is substantially greater than the width. The insulating elements form a grid configured in a manner substantially similar to the grid formed by the ribs and stringers, such that the insulating elements overlap the upper elements of the stringers and ribs. The grid of insulating elements is arranged between the second and third layers. Optionally, each insulating element comprises glass fibers embedded in a thermoplastic matrix.Additionally, the insulating elements may comprise a plurality of elongated stringer insulators overlapping the stringers and a plurality of elongated rib insulators overlapping the ribs that are shorter than the stringer insulators. The rib insulators may extend between the stringer insulators without substantially overlapping the stringer insulators. Furthermore, the stringer insulators may optionally be spaced from each other.

[006] Optionally, the composite coating may include additional layers of carbon fiber reinforced thermoplastic material and the grid of insulating elements may form a first grid and the plurality of insulating elements form a second grid configured in a substantially similar manner to the first grid of insulating elements. The second grid may be arranged between the additional layers of carbon fiber reinforced thermoplastic material so that the second grid is aligned with the first grid.

[007] Additionally, the aerostructure may include a second composite skin connected to the ribbed grid and stringers. Each Petition 870230087041, dated 02 / 10 / 2023, page 15 / 48 / 27 stringer and rib may include a lower element having a layer of thermoplastic material reinforced with unidirectional or woven carbon fiber forming a lower weld zone and the second coating may be connected to the lower elements of the ribs and stringers.

[008] According to a further aspect, the present invention provides an aerostructure in which a plurality of insulating elements form a grid and the insulating elements can be arranged to form a plurality of openings.

[009] According to another aspect, the present invention provides an aerostructure formed of thermoplastic comprising a semicrystalline thermoplastic in the polyaryletherketone family.

[0010] According to another aspect, the present invention provides an aerostructure formed of thermoplastic having a melting temperature above 260 degrees Celsius (500 degrees Fahrenheit).

[0011] According to a further aspect, an aerostructure is provided in which a laminate includes insulating elements and structural layers and the insulating elements are configured in such a way that the thermoplastic of the structural layers is kept below a melting temperature when the lower layer is heated to a temperature above the melting temperature by an induction welding head.

[0012] According to yet another aspect, an aerostructure is provided in which a laminate includes insulating elements and structural layers and the insulating elements are configured in such a way that the thermoplastic of a lower structural layer has a melting temperature and the insulating elements are configured to prevent the structural layers beyond the lower layer from heating above the melting temperature when the lower layer is exposed to an electromagnetic field sufficient to raise a portion of the lower laminate above the melting temperature.

[0013] Similarly, the present invention also provides a Petition 870230087041, dated 02 / 10 / 2023, page 16 / 48 / 27 aerostructure having a laminate formed of a plurality of insulating elements embedded in a plurality of structural layers and a bottom layer, wherein the thermoplastic of the bottom layer has a melting point and the insulating elements are configured to prevent the thermoplastic of the structural layers from melting when the bottom layer is welded into separate aerostructures by induction welding.

[0014] According to a further aspect, the present invention provides a composite aerostructure formed of a plurality of longitudinally elongated stringers, a plurality of elongated ribs connected to the plurality of stringers to form a grid, and a composite coating. The composite coating includes a plurality of structural layers, a plurality of insulating elements, and a weld layer. The structural layers are each formed of one-way or woven carbon fiber reinforced thermoplastic material. The insulating elements are formed of electrically insulating material and they form a plurality of insulating grids in which the insulating grids are aligned with each other and are arranged between the structural layers. The weld layer is also formed of one-way or woven carbon fiber reinforced thermoplastic material.The aerostructure also includes a plurality of connecting elements comprising a layer of unidirectional or woven fiber-reinforced thermoplastic material. Each connecting element is connected to one of the stringers or one of the ribs. Additionally, the carbon fibers of the weld layer are oriented in a first direction, and the carbon fibers of the connecting elements are oriented in a second direction transverse to the first direction. The weld layer overlaps and is connected to the connecting elements.

[0015] Furthermore, the present invention provides a composite laminate for use in an aerostructure. The laminate includes a plurality of structural layers, a plurality of insulating elements, and a layer Petition 870230087041, dated 02 / 10 / 2023, page 17 / 48 / 27 of welding. The structural layers are each formed of thermoplastic sheets reinforced with unidirectional or woven carbon fiber, and the fiber direction of at least some of the structural layers is transverse to the fiber direction of an adjacent structural layer. The insulating elements are formed of electrically insulating material and they form a plurality of insulating grids. The insulating grids are aligned with each other and are embedded in the structural layers between adjacent structural layers in which the fiber direction of the carbon fiber is transverse. The welding layer may also be formed of thermoplastic sheet reinforced with unidirectional or woven carbon fiber.

[0016] Furthermore, the present invention provides a method for forming a composite wing box. The method includes the steps of providing a plurality of spars, connecting a plurality of ribs to the plurality of spars, and forming a composite skin. The composite skin includes a plurality of structural layers, a plurality of insulating layers, and a weld layer. Each structural layer is formed of one-way or woven carbon fiber reinforced thermoplastic material. Each insulating layer is formed of a plurality of spaced electrically insulating elements. Each insulating element has length and width, and the length is substantially greater than the width. The insulating layers are aligned with each other and are arranged between the structural layers.The insulating layers are configured so that the insulating elements overlap the stringers and ribs when the composite sheathing overlaps the stringers and ribs. The weld layer is formed of thermoplastic material reinforced with unidirectional or woven carbon fiber. The method includes the step of positioning the composite sheathing over the ribs and stringers so that the layers of the composite sheathing overlap the ribs and stringers. The composite sheathing is then welded to the ribs and stringers. The step of... Petition 870230087041, dated 02 / 10 / 2023, page 18 / 48 / 27 welding comprises the step of transporting an induction welding head over the composite laminate adjacent to the ribs and stringers so that the induction welding head imposes an electromagnetic field through the composite laminate in such a way that the weld layer is heated above the melting temperature of the thermoplastic in the weld layer while the insulating layers prevent the structural layers from heating above the melting temperature of the thermoplastic.

[0017] Optionally, the method may include the step of connecting a plurality of connecting elements to the ribs and stringers. Each connecting element may include a layer of one-directional or woven carbon fiber reinforced thermoplastic, and the welding step may comprise welding the weld layer to the connecting elements. Additionally, the carbon fibers of the weld layer may be oriented in a first direction and the carbon fibers of the connecting elements may be oriented in a second direction. The step of connecting a plurality of connectors may comprise connecting the connectors so that the second direction is transverse to the first direction.

[0018] According to yet another aspect, the present invention provides a method that includes the step of providing a composite laminate having a plurality of insulating layers, which comprises the step of arranging the plurality of insulating elements in a grid.

[0019] According to a further aspect, the present invention provides a method that includes the step of providing a composite laminate having a plurality of insulating layers and the method comprises the step of arranging the plurality of insulating elements in such a way that a plurality of openings is formed between the insulating elements.

[0020] According to yet another aspect, the present invention provides a method including the step of forming a composite coating, which includes the step of providing pairs of structural layers in which Petition 870230087041, dated 02 / 10 / 2023, p. 19 / 48 / 27 each layer of a pair of structural layers is adjacent and directly connected to the other structural layer of the pair, and the two layers in a pair are oriented so that the fibers in both layers are substantially parallel. Adjacent pairs of structural layers are oriented so that the fibers in one pair are transverse to the fibers in the adjacent pair. Optionally, the method includes the step of providing insulating layers by placing an insulating layer between one pair and the adjacent pair. Additionally, an insulating layer may be placed between each adjacent pair of structural layers.

[0021] Additionally, according to another aspect, a method is provided that includes a method for forming a composite laminate for an aerostructure. The method includes the steps of providing a plurality of structural layers, each formed of thermoplastic sheets reinforced with unidirectional or woven carbon fiber, and providing a plurality of insulating elements formed of electrically insulating material, wherein each insulating element has a length and a width, and the length is substantially greater than the width. The method further includes the step of creating a plurality of insulating layers, wherein each layer is formed by the step of arranging the insulating elements in a pattern in which a plurality of the insulating elements are spaced from each other. The insulating layers are positioned between the structural layers by aligning the pattern in each insulating layer.The structural layers are arranged so that the bottom layer forms a weld layer. The method includes the step of consolidating the plurality of structural layers and the insulating layers by heating the layers and applying pressure to form a composite laminate with the insulating layers embedded within the structural layers. Optionally, the arrangement step comprises arranging a plurality of insulating elements so that the insulating elements extend between the plurality. Petition 870230087041, dated 02 / 10 / 2023, p. 20 / 48 / 27 of spaced insulating elements. Additionally, the arrangement step may include arranging the insulating elements in such a way that there are gaps between the separated insulating elements.

[0022] According to a further aspect, a method is provided that includes positioning a consolidated laminate over a bonding layer of one-way or woven carbon fiber reinforced thermoplastic material such that the fiber direction in a weld layer is transverse to the fibers in the bonding layer and the step of inducing an electromagnetic field through the thickness of the laminate and the bonding layer to heat the weld layer and the bonding layer sufficiently to weld the weld layer and the bonding layer to each other.

[0023] According to another aspect, a method is provided that includes the step of inducing an electromagnetic field by carrying an induction coil over a laminate following a pattern of insulation layers in the laminate.

[0024] Furthermore, the present invention provides a method that includes the step of inducing an electromagnetic field by concentrating an electromagnetic field across the width of a plurality of insulating elements. Optionally, a connection layer is rigidly connected to an airframe such that the step of inducing an electromagnetic field welds the laminate to the connection layer to securely connect the laminate to the airframe.

[0025] According to yet another aspect, a method is provided in which an aerostructure comprises a plurality of structural elements forming a pattern, and the method comprises aligning the pattern of the structural elements with a pattern of insulating layers in a laminate. The insulating layer may be formed of insulating elements arranged in a grid. Optionally, the step of arranging the insulating elements in a Petition 870230087041, dated 02 / 10 / 2023, p. 21 / 48 / 27 standard may include arranging the insulating elements in such a way that a plurality of openings is formed between the insulating elements.

[0026] Although the methods and apparatus are described herein by way of example for various embodiments and illustrative drawings, those skilled in the art will realize that the inventive methods and apparatus for sorting items using a dynamically reconfigurable sorting arrangement are not limited to the embodiments or drawings described. It should be understood that the drawings and detailed description thereof are not intended to limit the embodiments to the particular form described. Instead, the invention should cover all modifications, equivalents and alternatives that fall within the spirit and scope of the methods and apparatus for sorting items using one or more dynamically reconfigurable sorting arrangements defined by the appended claims. All headings used herein are for organizational purposes only and are not intended to limit the scope of the description or the claims.In the form used here, the word “may” is used in a permissive sense (that is, meaning having the potential to), rather than in a mandatory sense (that is, meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to. Description of the Drawings

[0027] The summary presented and the following detailed description of preferred embodiments of the present invention will be better understood when read in conjunction with the accompanying drawings, in which: Fig. 1 is an exploded perspective view of a wing box incorporating aspects of the present invention; Fig. 2 is a diagrammatic view of a system for forming the wing box of Fig. 1; Fig. 3 is an enlarged perspective view of a portion of the wing box from Fig. 1; Fig. 4 is a schematic side view of the box portion of Petition 870230087041, dated 02 / 10 / 2023, page 22 / 48 / 27 wing illustrated in Fig. 3. Detailed Description of the Invention

[0028] Referring now to the figures in general, and to Fig. 1 in particular, a composite aerostructure is generally designated by 10. In the present case, the aerostructure 10 is a wing box having an upper skin 40 and a lower skin, both of which are supported by a support structure 15. The upper and / or lower skin(s) is / are formed of a carbon fiber reinforced thermoplastic material. The composite skin includes insulating elements and thus the skin can be efficiently welded to the support structure without heating most of the skin, which could cause damage to the skin. In particular, the skin 40 is formed of a laminate that is configured to localize the heating effect produced by an induction welding head to limit the heating of the skin so that only a portion of the skin in a weld zone is heated to a welding temperature.

[0029] Referring to Fig. 1, the details of the aerostructure will be described in more detail. In Fig. 1, the aerostructure incorporates a laminate in the structure of a wing box. However, it should be understood that this is merely an exemplary structure; the laminate can be incorporated into a variety of composite structures. Additionally, although the laminate has particular application in an aerostructure, the laminate is not limited to use in an aerostructure.

[0030] The aerostructure 10 in Fig. 1 is a wing box that includes an underlying support structure 15 and a cover that overlays the support structure. In the present case, the cover 40 is referred to as a skin and is shown in Fig. 3. For clarity, in Fig. 1 the skin is shown with structural layers separate from the insulation layers, and only a single structural layer is shown (designated 50). Additionally, in Fig. 1 Petition 870230087041, dated 02 / 10 / 2023, page 23 / 48 / 27 the assembly is illustrated with a single sheath that overlaps the top of the support structure. However, it should be understood that the assembly 10 may also include a bottom sheath that covers the base of the support structure. The bottom sheath may be formed of a laminate similar to the laminate of the top sheath 40. Additionally, the top or bottom sheaths may wrap around the front or rear edge of the support structure to form a closed assembly.

[0031] The support structure 15 can be any one of a variety of configurations depending on the application for the structure. In the present case, the support structure 15 is formed of a plurality of elongated spars and ribs. A leading spar 20 extends through the length of the wing box. A first end of the leading spar is connected to a first end rib 30, and a second end of the leading spar is connected to a second end rib 30 so that the leading spar extends a distance between the two end ribs. The end ribs 30 extend through the width of the wing box and are transverse to the leading spar 20. The leading spar 20 is an elongated beam having a central web having a height and a thickness, wherein the height is substantially greater than the thickness.The web of the front stringer can be incorporated into any of a variety of beam configurations, such as a box girder, channel girder, or I-beam. In the present case, the stringer can be a channel girder with the web extending between an upper surface 22 and a lower surface 24. As described below, the upper and lower surfaces 22, 24 can form connecting surfaces to connect the linings 40 to the stringers.

[0032] A rear longitudinal member 25 spaced from the front longitudinal member 20 is also connected to the two end ribs 30 so that the rear longitudinal member extends the length between the ribs of Petition 870230087041, dated 02 / 10 / 2023, p. 24 / 48 / 27 end. The rear longitudinal member 25 can be configured in a substantially similar manner to the front longitudinal member. In the present case, the rear longitudinal member 25 is substantially similar to the front longitudinal member, except that the rear longitudinal member is smaller than the front longitudinal member. In this way, the interconnected longitudinal members 20, 25 and the end ribs 30 form the sides of a support structure in a general box shape 15. Additionally, the support structure 15 may include a plurality of additional elements to stiffen and / or reinforce the structure. For example, the support structure 15 may include additional longitudinal members that extend through the length of the structure. In the present case, the support structure 15 includes a plurality of intermediate ribs 35 that extend through the width of the support structure.

[0033] In the present embodiment, the height of the ribs 30, 35 tapers to form a conical wing box. In particular, the height of the ribs 30, 35 adjacent to the front spar 20 is greater than the height of the ribs 30, 35 adjacent to the rear spar 25. The intermediate ribs 35 are spaced from the end ribs 30 and from each other. The ribs 30, 35 can be configured as elongated beams, similar to the spar 20, 25 as described herein. In the present case, the ribs 30, 35 are configured similarly to channel beams, having a central web that extends between the upper and lower transverse legs. Additionally, similar to the stringers, the upper and lower legs of the ribs 30, 35 can form surfaces that make contact with the linings 40 to provide connection points between the linings and the support structure 15.Specifically, the end ribs 30 may include upper and lower flanges 32, 34 that form contact surfaces, and the intermediate ribs 35 may include upper and lower flanges 37, 38 that form contact surfaces.

[0034] Referring now to Figs. 1 and 3-4, the details of the laminate that forms the coating 40 will be described in more detail. The laminate Petition 870230087041, dated 02 / 10 / 2023, page 25 / 48 / 27 includes a plurality of structural layers 50, 52, 54, 56, 58 with a plurality of insulating elements 60 embedded between one or more structural layers. Each structural layer comprises reinforcing elements embedded in a matrix material. Depending on the application, the reinforcing elements can be any of a variety of reinforcing materials. By way of example, the reinforcing elements can be elongated filaments or glass or carbon fibers. For example, an exemplary carbon fiber is a continuous high-strength, high-strain PAN-based fiber in bundles of 3,000 to 12,000. These reinforcing fibers can be surface-treated and can be sized to improve their interlaminar shear properties with the matrix material.However, it should be understood that these materials are meant to be examples; other materials may be used depending on the environment in which the laminate is to be used.

[0035] Reinforcing elements are embedded in a matrix material, such as a polymer. Depending on the application, any of a variety of polymers can be used for the matrix material, including amorphous, crystalline, and semicrystalline polymers. In the present case, the matrix material is a thermoplastic material, such as a thermoplastic elastomer. More specifically, the thermoplastic material is a semicrystalline thermoplastic. In particular, the thermoplastic may be a thermoplastic polymer in the polyaryletherketone (PAEK) family, including but not limited to polyetheretherketone (PEEK) and polyetheretherketone (PEKK).

[0036] As noted here, structural layers 50, 52, 54, 56, 58 may be composite materials, which may be carbon fiber reinforced thermoplastic composites. In particular, the blade may be thermoplastic prepregs, which are blades in which the reinforcing materials have been pre-impregnated with resin. For example, the prepreg may be prepregs Petition 870230087041, dated 02 / 10 / 2023, page 26 / 48 / 27 thermoplastics produced by coating reinforcing fibers with a thermoplastic matrix. A prepreg sheet like this has the capacity to be reheated and reformed by heating the sheet above the melting point of the thermoplastic matrix. Several exemplary prepreg materials that can be used to form the structural elements 25, 26 include, but are not limited to, materials produced by TenCate Advanced Composite USA of Morgan Hill, California and marketed under the name CETEX, such as TC1200, TC1225 and TC1320. TC1200 is a semicrystalline PEEK composite reinforced with carbon fiber having a glass transition temperature (Tg) of 143°C / 289°F and a melting temperature (Tm) of 343°C / 649°F. TC1225 is a semicrystalline PAEK composite reinforced with carbon fiber having a Tg of 147°C / 297°F and a Tm of 305°C / 581°F.TC1320 is a semi-crystalline PEKK composite reinforced with carbon fiber having a Tg of 150°C / 318°F and a Tm of 337°C / 639°F.

[0037] Referring again to Fig. 1, the laminate 40 comprises a plurality of structural layers configured to support the structural load. A plurality of insulation layers 60 is embedded within the structural layers. Although the insulation layers may be configured to support structural load, in the present case, the insulation layers are configured to insulate the heating of the laminate during welding without supporting significant structural load, if any. To illustrate the details of the insulation layers 60, in Fig. 1, the insulation layers 60 are shown separately from the structural layers of the laminate, along with a single structural layer 50 of the laminate. In the embodiment illustrated in Fig. 1, a plurality of aligned and overlapping insulation layers 60 is shown; however, it should be understood that the number and location of the insulation layers may vary depending on the application.

[0038] The 60 insulation layers are embedded in a material Petition 870230087041, dated 02 / 10 / 2023, page 27 / 48 / 27 of matrix. Preferably, the matrix material is a thermoplastic material that can be fused by heating with the other layers in the laminate. By fusion by heating of the matrix material of the insulation layer, the insulation layer is integrally formed with the laminate. In particular, in the present case, the insulation layers are formed of a composite material having a matrix that is substantially similar to the matrix material of the structural layers. For example, the resistive elements are carbon fibers and the matrix material is a thermoplastic material, such as a semi-crystalline thermoplastic in the polyaryletherketone (PAEK) family.

[0039] The insulation layers 60 provide electrical insulation between the portions of the structural layers when an electromagnetic field is applied to the laminate adjacent to the insulation layers 50. The insulation layers 60 may comprise any of a variety of electrically insulating materials. Preferably, the insulation layers 60 comprise a thermoplastic material. In the present case, the insulation layer comprises one or more sheets of glass-reinforced thermoplastic.

[0040] Insulation layers 60 are configured to isolate heat from a heating process to a particular zone or area of ​​the laminate. It should be understood that while insulation layers 60 limit the heating of the structural layers, the insulation layers do not limit heating, providing significant thermal insulation. Instead, the insulation layers provide electrical insulation to selectively isolate different areas so that they are not heated by inductive heating.

[0041] For example, during a process in which the cladding 40 is welded to the support structure 15, the insulation layers limit the heat created during the welding process so that only a tarp or Petition 870230087041, dated 02 / 10 / 2023, page 28 / 48 / 27 selected plies of the laminate are heated, and only in certain areas of the selected ply or plies. In this way, the insulation layers 60 are configured to form a pattern that corresponds to the portions of the laminate intended to be heated. Specifically, the insulation layers can be configured to form a pattern that corresponds to the portions of the laminate intended to be welded. In particular, the pattern can correspond to the areas of the laminate that make contact with the part from which the laminate is to be welded. For example, the insulation layer 60 can be formed to correspond to the pattern formed by the upper surfaces of the stringers 20, 25 and the ribs 30, 35 (for example, the upper surfaces 22, 27, 32 and 37).

[0042] Each 60 insulation layer can be formed from a single piece of insulating material configured in the desired pattern. In some cases, the pattern may be a solid pattern so that the insulating material simply forms a block, strip, or similar pattern. However, in the present case, the 60 insulation layer forms a pattern having a plurality of openings so that the 60 insulation layer overlaps less than a larger portion of the laminate area. In some cases, the insulation may form a pattern having sufficient open areas so that the insulation overlaps less than 40% of the overall laminate area. Additionally, in some applications, the insulation layer may form a pattern having sufficient open areas so that the insulation overlaps less than 30% of the overall laminate area.Additionally, in some applications, it may be desirable to configure the insulation layer to have sufficient open areas so that the insulation overlaps less than 20% of the overall laminate area. Furthermore, the insulation layer in the illustrated structure forms a pattern that covers at least approximately 5% of the overall laminate area.

[0043] Referring again to Fig. 1, in this case, the layer Petition 870230087041, dated 02 / 10 / 2023, page 29 / 48 / 27 of insulation 60 forms a grid pattern of a plurality of intersecting strips of insulating material. Specifically, insulation layer 60 is formed of a plurality of elongated insulation elements having a length and a width, wherein the length is significantly greater than the width. An exemplary material for forming the insulation elements is a fiberglass tape embedded in thermoplastic material. A first group of insulation elements forms stringer insulation elements 70 that extend at least substantially throughout the length of stringers 20, 25. As shown in Fig.1. The stringer insulation elements 70 are arranged so that a first stringer insulation element overlaps the upper surface 22 of the front stringer 20 and a second stringer insulation element 70 overlaps the upper surface 27 of the rear stringer 25. A pair of end rib insulation elements 80 are arranged adjacent to the ends of the rear stringers so that the end rib insulation elements overlap the upper surfaces 32 of the end ribs. Similarly, a plurality of insulating elements 82 extend between the stringer insulating elements 72 to overlap the intermediate ribs 35. As can be seen, the ribs 30, 35 extend rearwards beyond the rear stringer 25. Therefore, the intermediate rib insulating elements can extend over the stringer insulating element 70, overlapping the rear stringer 25.In this way, the rib insulation element 82 and the stringer insulation element 70 would overlap to form an insulation element having a thickness of two layers. However, in the present case, the insulation elements of the insulation layer do not overlap substantially, so that substantially the entire insulation layer has the thickness of a single layer. Therefore, to prevent substantial overlapping of insulation elements, the elements... Petition 870230087041, dated 02 / 10 / 2023, p. 30 / 48 / 27 of intermediate rib insulation are formed in two segments: a first segment 82 extends over the intermediate stringers and extends between the stringer insulation elements 70; and a second segment 84 extends over the rear end of the intermediate ribs 35 so that the second segments extend outward from the stringer insulation element 70 that overlaps the rear stringer.

[0044] As can be seen from the above, the insulation layer 60 forms a pattern having a plurality of open areas. In particular, the insulation layer forms a pattern that forms a grid to connect the laminate 40 to the top of the ribs and stringers.

[0045] In some applications, it may be desirable to vary the pattern or size of the different insulation layers so that different insulation layers insulate different plies of the laminate. However, in the present case, each of the 60 insulation layers is substantially similar. Specifically, each 60 insulation layer has a similar size and pattern. Additionally, as shown in Fig. 1, each of the 60 insulation layers in the laminate is aligned so that the insulation elements that form the pattern for each layer overlap the corresponding elements in the other insulation layers.

[0046] As discussed herein, each of the structural layers 50, 52, 54, 56, 58 and the insulating layers 60 may comprise layers of reinforced thermoplastic composite materials. In this way, the structural layers and the insulating layer can be integrally connected by fusing the layers. Specifically, the layers can be consolidated by applying sufficient heat to raise the layers above the melting point of the thermoplastic matrix and applying sufficient pressure to fuse the layers together. In this manner, the insulating layers 60 are embedded in the laminate between the structural layers.

[0047] The number of structural plies and the orientation of the plies in Petition 870230087041, dated 02 / 10 / 2023, page 31 / 48 / 27 laminate may vary depending on the application. Additionally, the orientation of the plies and the positioning of the insulation layers may be varied depending on the desired thermal insulation. Figs. 3 and 4 illustrate an exemplary arrangement of laminate 40. However, it should be understood that the number of plies, the orientation of the plies, as well as the number and location of the insulating layers 60 are only an example; the invention is not limited to the arrangement illustrated in this exemplary laminate.

[0048] The laminate includes ten structural layers designated 50a,b, 52a,b, 54a,b, 56a,b and 58a,b. As described herein, each structural layer may be a canvas or composite material layer, such as one-directional carbon fiber reinforced thermoplastic tape or woven fabric. The fiber direction for each structural layer may vary to provide strength in a plurality of directions. However, in the present case, the layers may be arranged in pairs, wherein the fiber direction in both layers in the pair is parallel. For example, the first layer in the laminate is designated 50a and has a fiber direction of 90° and the second layer in the laminate (designated 50b) also has a fiber angle of 90°. These first two layers 50a, 50b form a pair that are adjacent to each other and affixed to each other. The third and fourth structural layers comprise the second pair of layers 52a, 52b. Each layer of this second pair has a fiber direction of 0°.The fifth and sixth structural layers comprise the third pair of layers 54a, 54b. Each layer of the third pair has a fiber direction of 45°. The seventh and eighth structural layers comprise the fourth pair of layers 56a, 56b. The laminate can be formed so that it is symmetrical around its midline, which, in this case, is the third pair of layers. Thus, the fourth pair of structural layers 56a, 56b can have a fiber direction that is similar to the fiber direction of the second pair of structural layers (e.g., 0°). Similarly, the ninth and tenth layers form the fifth pair, and each layer of the fifth pair can have a... Petition 870230087041, dated 02 / 10 / 2023, page 32 / 48 / 27 90° fiber direction. It should be noted that the layers do not need to be arranged in pairs. For example, as shown in Fig. 4, the layers are arranged in pairs. However, in Fig. 3, the top and bottom layers 52, 58 are arranged as single layers, while the six plies between the top and bottom layers are arranged in pairs.

[0049] The 60 insulation layers are selectively inserted between structural layers of the laminate. Although insulation layers can be inserted between each layer of the laminate, in the present case, the insulation layers are inserted between fewer than all structural layers. In particular, the insulation layers are inserted between layers having a selected characteristic. For example, in the present case, the selected characteristic is a change in fiber direction. A 60 insulation layer is inserted between adjacent layers having a different fiber angle. Thus, in the above-described arrangement, the 60 insulation layers are arranged between pairs of structural layers, but not within the layers in the pair. More specifically, referring to Figs. 3-4, the first 60a insulation layer is positioned between layer 50 (in Fig. 3) or 50b (in Fig. 4).4) and layer 52a because the interface between layer 50 / 50b and layer 52a is an interface where the fibers in adjacent layers are transverse to each other (i.e., the fiber angle changes from 90° to 0°). Similarly, the second insulating layer 60b is positioned between layer 52b and layer 54a because the fiber angle changes from 0° to 45°. The third insulating layer 60c is positioned between the third and fourth pairs (i.e., the interface of layers 54b and 56a) where the fiber angle changes from 45° to 0°. The fourth insulating layer 60d is positioned between the fourth and fifth pairs (i.e., the interface of layers 56b and 58a or layer 58 in Fig. 3) where the fiber angle changes from 0° to 90°.

[0050] It should be noted that the thickness of the layers in the Figures is not to scale and, in some cases, the thickness is exaggerated for purely illustrative purposes. Petition 870230087041, dated 02 / 10 / 2023, p. 33 / 48 / 27 illustrative effects. For example, in Fig. 2, the structural layers 50, 52, 54, 56, 58 and the insulating layers 60 are represented as having gaps between adjacent layers. However, it should be understood that the layers in the laminate are consolidated layers in which the different layers have been fused together. Additionally, as noted above, each insulation layer 60 is described as a single layer of insulating material formed of one or more insulating elements. However, it may be desirable in certain applications to increase one or more of the insulation layers so that the insulation layer(s) may be formed of multiple layers of insulating material. Additionally, as shown in Fig. 2, the insulating layer 60 may not be a continuous layer extending the entire length and width of the laminate, as shown in Fig. 1.Instead, the 60-layer insulation may only cover a small portion of the area of ​​the structural layers.

[0051] Laminate 40 can be formed using a variety of processes. The details of a method for forming laminate 40 from a plurality of reinforced thermoplastic layers will now be described. Additionally, the method for forming an aerostructure using the laminate will also be described.

[0052] A plurality of layers of reinforced thermoplastic carbon fiber tape is arranged one on top of the other to form a plurality of plies that are structural layers. The fiber orientation in the plies can be varied, and insulating plies can be positioned at the interface of plies having transverse fiber orientations. For example, the layers can be formed of ten structural plies and four insulating layers oriented at 90°, 90°, Ins, 0°, 0°, Ins, 45°, 45°, Ins, 0°, 0°, Ins, 90°, 90° (where “Ins” refers to an insulating layer). The insulating layers are formed of one or more insulating elements forming a pattern. The insulating layers can be aligned across the thickness of the laminate so that the pattern of each Petition 870230087041, dated 02 / 10 / 2023, page 34 / 48 / 27 insulating layer overlaps the pattern of the other insulating layers in the laminate. In this exemplary laminate, the carbon fiber layers of the structural layers are formed of one-way carbon fiber reinforced tape of PEEK / AS4 and the insulation layers are formed of one-way thermoplastic glass fiber reinforced tape of PEEK / S2.

[0053] The structural layers and the insulating layers are consolidated to form a laminate by heating the assembled layers under pressure. For example, the assembly may be heated to a temperature above the melting point. In the present case, the assembled layers are heated to approximately 725° under a pressure of approximately 0.206 MPa (30 psi). After the assembled layers reach 725°, the pressure is increased to approximately 0.689 MPa (100 psi) and the assembly is held at the elevated temperature for an extended period, such as approximately 30 minutes. The pressure is then removed and the consolidated laminate is cooled to room temperature.

[0054] Formed as described herein, the laminate can be connected to one or more separate elements to form the structure. An example structure is an aerostructure. More specifically, the laminate is configured so that it can be welded to a separate structure. Additionally, the laminate is constructed so that the heat generated during the welding process is insulated in a selected tarp or tarps of the laminate. Furthermore, the generated heat can be insulated in selected areas of the selected tarp. The welding process of the laminate to a separate element will now be described in more detail.

[0055] As described herein, the laminate is formed with one or more insulating layers. The insulating layer(s) may be formed according to a pattern. In particular, the pattern may be similar to the contact area of ​​the separate element or assembly that is to be welded to the laminate. For example, referring to Fig. 1, the insulating layer may form a grid. Petition 870230087041, dated 02 / 10 / 2023, page 35 / 48 / 27, which is modeled similarly to the grid formed by ribs 30, 35 and stringers 20, 25 of the support structure 15. Thus, the method includes the step of aligning the pattern of the insulating layer(s) with the grid formed by the ribs and stringers. Referring to Fig. 2, the upper surface of the support structure comprises one or more connecting elements for welding the support structure to the laminate. In particular, ribs 30, 35 and stringers 20, 25 can be formed so that the upper surface 22, 27, 32, 37 forms connecting elements. Alternatively, the connecting elements can be separate elements that are fixedly connected to the ribs and stringers.

[0056] In the illustrated embodiment, the connecting element is a ply of carbon fiber reinforced thermoplastic material similar to the material that forms the structural plies of the laminate 40. In Fig. 2, the connecting element is designated 39 and is illustrated as a laminate fixedly connected to the top of the flange 37 of the intermediate rib 35. However, it should be understood that the connecting element may be an integral part of the underlying structure. For example, the ribs 35 may be formed in such a way that the flange 37 is formed of carbon fiber reinforced thermoplastic material that would operate as the connecting element. Alternatively, the connecting element may be a separate element that is mechanically fastened, such as by a clamp or a fastener.

[0057] The fiber direction of the carbon fibers in the connecting element 39 can be oriented in a direction that is transverse to the fiber direction of the lower ply 58b of the laminate. The laminate 40 is placed over the structure so that the lower ply 58b makes contact with the connecting element(s) 39, with the insulating layers 60a,b,c,d aligned with the connecting elements. An induction welding head 100 is then placed in operative engagement with the laminate to induce an electromagnetic field through the thickness of the laminate. In particular, the head of Petition 870230087041, dated 02 / 10 / 2023, page 36 / 48 / 27 induction welding 100 moves over the top surface of the laminate. The welding head does not need to make contact with the top surface; however, the welding head is sufficiently close to the top surface of the laminate to induce an electromagnetic field through the thickness of the laminate having sufficient strength to weld the bottom layer 58a and the connecting element 39.

[0058] The 100 welding head heats the bottom layer and the connecting element by electromagnetic induction, through the heat generated by eddy currents. The welding head includes an electronic oscillator that passes a high-frequency alternating current through an electromagnet. The rapidly alternating magnetic field then penetrates the laminate and the connecting element to generate eddy currents which, in turn, heat the bottom layer and the connecting element.

[0059] In the present case, the welding head induces an electromagnetic field through the laminate and the connecting elements, such that the adjacent layers having transverse carbon fibers heat up in response to the electromagnetic field. However, layers that are separated by the insulating layers 60 do not heat up above the melting temperature in response to the electromagnetic field. In particular, in the present case, the electromagnetic field produced by the welding head is sufficient to heat the lower layer 58a and the connecting element 39 above the melting temperature of the thermoplastic matrix material for the lower layer and the connecting element. After raising the lower layer and the connecting element above the melting point of the layer while still applying pressure, the lower layer fuses with the connecting element to weld the two items together. Additionally, as noted herein, the insulating layers 60 insulate the adjacent layers from the inductive heat caused by the welding head.In particular, it should be noted that part of the electromagnetic field may extend beyond the edges of the insulating elements of the insulating layer. Therefore, the electromagnetic field may... Petition 870230087041, dated 02 / 10 / 2023, page 37 / 48 / 27 induce a certain heating in the structural layers. However, the induced heating will be substantially less than the heating induced between the non-insulated layers (i.e., 58b and 39) and will be substantially below the melting point of the structural layers. In this way, the insulating layers limit the heating of the structural layers below the melting temperature while still allowing the lower layer and the connecting element to be heated above the melting temperature. Therefore, although the insulating layers do not necessarily prevent all heating of the layers adjacent to the insulating layers, for the purposes of this methodology, the insulating layers prevent heating of the layers if the insulating layers limit the heating of the layers substantially below the melting point.

[0060] In Fig. 2, the welding head 100 is shown inducing an electromagnetic field through the laminate to weld the laminate to the rib 35. The method includes the step of controlling the displacement of the welding head so that the welding head is carried over the laminate to weld a plurality of points of the laminate to the support structure 15. In particular, the method may include the step of controlling the position of the welding head to follow the pattern formed by the insulating layer. In this way, the welding head welds the laminate to the support structure along the areas corresponding to the pattern formed by the insulating layer 60.

[0061] In the description provided, the laminate is described as a flat laminated panel. However, it should be understood that the invention is not limited to flat panel structures. For example, the laminate can be used in a variety of structures in a variety of fields and may have particular application in the aerospace field to provide a variety of components, including but not limited to cells, nacelles and airfoils, such as wings, elevators, etc. The laminate 40 described herein can be formed into a curved structure and connected to a separate element or structure. Petition 870230087041, dated 02 / 10 / 2023, page 38 / 48 / 27

[0062] Those skilled in the art realize that changes or modifications can be made to the above-described embodiments without departing from the general inventive concepts of the invention. Therefore, it should be understood that this invention is not limited to the particular embodiments described herein, but should include all changes and modifications that are within the scope and spirit of the invention presented in the claims. Petition 870230087041, dated 02 / 10 / 2023, pp. 39 / 48

Claims

1 / 4 CLAIMS 1. Aerostructure (10), characterized in that it has an enclosure disposed in its interior, comprising a coating formed from a composite material, the coating having a shape and configuration to provide the enclosure in its interior, and the composite material including joint layers of at least one first layer of material and at least one second layer of material, the first layer of material including a one-way carbon fiber reinforced thermoplastic material and the second layer of material including an electrically insulating material.

2. Aerostructure (10) according to claim 1, characterized in that at least one first layer of material includes a plurality of first layers of material and at least one second layer of material includes a plurality of second layers of material, with those selected from the first layers of material and from the second layers of material arranged in an alternating layer stack.

3. Aerostructure (10) according to claim 2, characterized in that the plurality of first layers of material includes a first layer having the unidirectional carbon fibers oriented in a first direction and a second layer having the unidirectional carbon fibers oriented in a second direction different from the first direction.

4. Aerostructure (10) according to claim 3, characterized in that the first and second directions are oriented 0 degrees relative to each other.

5. Aerostructure (10) according to claim 3, characterized in that the first and second directions are oriented 45 degrees to each other.

6. Aerostructure (10) according to claim 3, Petition 870230087041, dated 10 / 02 / 2023, page 40 / 48 2 / 4 characterized in that the first and second directions are oriented 90 degrees to each other.

7. Aerostructure (10) according to claim 2, characterized in that the stack of alternating layers is configured such that an electromagnetic field applied near a first side of the stack is capable of fusing a first layer of selected unidirectional carbon fiber reinforced thermoplastic material located on a second side of the stack opposite the first side, without fusing a first layer of selected unidirectional carbon fiber reinforced thermoplastic material on the first side of the stack.

8. Aerostructure (10) according to claim 2, characterized in that the stack of alternating layers is configured such that the cooperation between the electrically insulating material and an electromagnetic field applied near a first side of the stack is able to fuse a first layer of selected unidirectional carbon fiber reinforced thermoplastic material located on a second side of the stack opposite the first side, without fusing a first layer of selected unidirectional carbon fiber reinforced thermoplastic material on the first side of the stack.

9. Aerostructure (10) according to claim 1, characterized in that the unidirectional carbon fiber lies within a plane containing the first layer of material.

10. Aerostructure (10) according to claim 1, characterized in that it comprises a support structure disposed in the enclosure.

11. Aerostructure (10) according to claim 10, characterized in that the cladding is wrapped around the support structure to form a closed support assembly.

12. Aerostructure (10) according to claim 10, Petition 870230087041, dated 10 / 02 / 2023, page 41 / 48 3 / 4 characterized in that the support structure comprises stringers (20, 25), ribs (30, 35) or combinations thereof.

13. Aerostructure (10) according to claim 1, characterized in that the electrically insulating material includes glass.

14. Aerostructure (10) according to claim 1, characterized in that the skin includes a separate upper skin piece and a separate lower skin piece, each piece joined to the other to provide the skin having an enclosure disposed therein.

15. Aerostructure (10) according to claim 1, characterized in that the one-way carbon fiber reinforced thermoplastic material is a pre-impregnated material.

16. Aerostructure (10) according to claim 1, characterized in that the carbon fiber reinforced thermoplastic material comprises a polymer in the polyaryletherketone (PAEK) family.

17. Aerostructure (10) according to claim 1, characterized in that joint layers of at least one first layer of material and at least one second layer of material are provided in the form of a consolidated laminate.

18. Aerostructure (10) according to claim 1, characterized in that the electrically insulating material includes a material that can be thermally fused with the one-way carbon fiber reinforced thermoplastic material.

19. Aerostructure (10) according to claim 1, characterized in that the second layer of material is configured to form a pattern that corresponds to the portions of the coating that are intended to be heated.

20. Aerostructure (10) according to claim 19, characterized in that the pattern has a plurality of openings. Petition 870230087041, dated 02 / 10 / 2023, page 42 / 48 4 / 4 21. Aerostructure (10) according to claim 1, characterized in that the second layer of material is a glass tape. Petition 870230087041, dated 02 / 10 / 2023, pp. 43 / 48

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