WO2015142171A1 - Élément de raccordement de structure primaire pour aéronef et procédé de fabrication de l'élément de raccordement - Google Patents

Élément de raccordement de structure primaire pour aéronef et procédé de fabrication de l'élément de raccordement Download PDF

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Publication number
WO2015142171A1
WO2015142171A1 PCT/NL2015/050170 NL2015050170W WO2015142171A1 WO 2015142171 A1 WO2015142171 A1 WO 2015142171A1 NL 2015050170 W NL2015050170 W NL 2015050170W WO 2015142171 A1 WO2015142171 A1 WO 2015142171A1
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WO
WIPO (PCT)
Prior art keywords
connecting element
aircraft
frame
primary
rib
Prior art date
Application number
PCT/NL2015/050170
Other languages
English (en)
Inventor
Jan Willem Gunnink
Jacobus Wilhelmus Cornelis Anna Gofers
Original Assignee
Gtm Holding B.V.
Gofers Beheer B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from NL2012457A external-priority patent/NL2012457B1/en
Application filed by Gtm Holding B.V., Gofers Beheer B.V. filed Critical Gtm Holding B.V.
Priority to EP15715492.3A priority Critical patent/EP3119577A1/fr
Publication of WO2015142171A1 publication Critical patent/WO2015142171A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0005—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor using fibre reinforcements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
    • B64C1/06—Frames; Stringers; Longerons ; Fuselage sections
    • B64C1/061—Frames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2071/00—Use of polyethers, e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2081/00—Use of polymers having sulfur, with or without nitrogen, oxygen or carbon only, in the main chain, as moulding material
    • B29K2081/04—Polysulfides, e.g. PPS, i.e. polyphenylene sulfide or derivatives thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/12—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of short lengths, e.g. chopped filaments, staple fibres or bristles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • B29L2031/3076—Aircrafts

Definitions

  • the invention relates to connecting an aircraft skin to an aircraft (sub) structure, in particular to an aircraft reinforcing element, for example to a frame or to a rib.
  • the invention further relates to a connecting element for fastening an aircraft skin to a primary aircraft reinforcing element, and to an aircraft comprising the connecting element.
  • the primary structure of an aircraft consists, in case of a fuselage for instance, of multiple shape defining frames and stringers that typically extend between the frames.
  • primary structures such as wings, vertical and horizontal tail planes
  • ribs are used as reinforcing elements.
  • the aircraft fuselage skin is connected to the frames by means of elements known as castellation's, shear webs, clips (short shear webs) and frame stabilizing elements (cleats or stabilizers).
  • frame stabilizing elements cleats or stabilizers.
  • Rib stabilizing elements are used in combination with shear webs or clips to fix the aircraft wing and tail plane skin to the ribs.
  • a rib stabilizing element therefore is a cleat that is fastened to a rib and to the wing or tail plane skin. This can be performed directly to and only to these skins or to the stringers as well as to skin and stringers.
  • the connection between the aforementioned elements is usually achieved by a riveted connection.
  • bolts for example those known as Hi-Loks, Hi-Lites and lockbolts may also be used in the context of the present invention.
  • a bonded connection can also be applied, as well as combinations of mechanical fastening (bolts and/or rivets) and bonding.
  • the castellations, shear webs, clips, frame and rib stabilizing elements used nowadays are based on a fiber reinforced composition, typically comprising carbon fibres.
  • Clips and cleats are typically made by a production process, in which an assembled, multi-layered raw material is used.
  • a sheet of the desired size and shape is pressed out of the multi- layered raw material, and subsequently heated in sheet form and adapted (folded) in a substantially solid state to the contours of a mould in the shape of the final component.
  • the edges are then trimmed and/or removed, for instance by sawing or grinding, in order to obtain the exact form of the component.
  • An edge sealing is usually required to prevent dry carbon fibres from being exposed at the borders. Exposed carbon fibers are prone to galvanic corrosion, which should be prevented, at least at locations with materials and structures prone to galvanic action with carbon fibres.
  • the above described production method starts from a relatively flat multi-layered sheet and there is a reliance on the given form of the mould with regard to the radii that are created on the component produced. Trimming and edge sealing furthermore makes the known process very labour- and cost-intensive, since it requires a number of intermediate steps. In particular in the case of shear webs, and frame and rib stabilizing elements, which are applied in numbers of 3000 to over 10 000 per aircraft, the known process entails an enormous amount of work for the production of an aircraft.
  • the present invention aims to provide an improved primary structure of an aircraft, in particular with regard to the amount of work involved and the costs as well as improved structural performances.
  • the invention in particular aims to provide a connecting element for fastening an aircraft skin to a primary aircraft reinforcing element which offers the desired primary load capacity and yet can be produced in a reliable and cost-effective manner.
  • a connecting element in accordance with claim 1.
  • a connecting element comprising a shear web and, integrally formed therewith, a frame or rib stabilizing element, wherein the connecting element comprises a fibre - reinforced composition of discontinuous fibres in a thermoplastic or thermoset matrix material, the connecting element is configured to transfer primary loads between the aircraft skin and the primary aircraft frame or rib, and at least part of the discontinuous fibres are intentionally and controllably oriented along paths of primary load transfer.
  • a particularly useful method for producing a connecting element in accordance with the invention concerns injection moulding.
  • thermoplastic or thermoset matrix material Injection moulding of discontinuous fibers embedded in a thermoplastic or thermoset matrix material is known per se but has not been used for aircraft primary structural parts before, due to the general believe that the stiffness and strength offered by injection moulded components would be too low for application in aircraft primary structures. This prejudice has been overcome by configuring the connecting element in accordance with the invention, as will be elucidated in more detail below.
  • the injection molding method in accordance with the invention comprises the steps of: providing a fibre-reinforced thermoset or thermoplastic composition,
  • thermoset composition or cooling the thermoplastic composition, and removing the primary structure connecting element produced from the injection- moulding device
  • the connecting element is configured to transfer primary loads between the aircraft skin and the primary aircraft frame or rib, and the position of the one or more inlets is selected such that at least a part of the discontinuous fibres are intentionally and controllably oriented along paths of primary load transfer.
  • the term "primary structural connecting element” should be seen as covering in particular a castellation, shear web, a frame stabilizing element, a clip or a rib stabilizing element as exemplary embodiments.
  • the "primary structural element” can also be an integrally part of the substructure, i.e. frame and/or rib or a section thereof. In that case the frame/rib or frame/rib-section is also injection moulded.
  • shear web should be understood as a means of introducing shear in a frame. This corresponds to the usual understanding of a person skilled in the art. It is understood as meaning a device for fixing a frame or a rib to the aircraft structure. A shear web thereby connects a frame or a rib to apart of the skin of the aircraft and extends over a number of stringers provided in between the frames or ribs.
  • clip should be understood as meaning a kind of short shear web in the sense that a clip only extends from a first stringer foot to a second stringer foot.
  • Figure 6 shows a shear web 605
  • Figure 4 shows a clip 401, which in its installed position is only arranged between two stringers.
  • frame stabilizing element should be understood as meaning a cleat or stabilizer.
  • a "rib stabilizing element” is a stabilizing element similar to a frame stabilizing element that is used on a rib, that is to say for example in the area of a wing, a vertical tail surface or a horizontal tail surface.
  • the rib stabilizing element supports and stabilizes a rib of the aircraft.
  • Castellation's are elements similar to shear webs, but with the objective to have some flexibility between frame and aircraft fuselage skin. In general these castellation's will be applied to small aircraft up to medium sized transport aircraft.
  • a connecting element is configured such that it is provided with a shear web comprising flanges for establishing a connection to the aircraft skin or to a stringer, whereby the flanges extend at an angle with a planar web section of the shear web and at both sides of the planar web section of the shear web.
  • the angle differs from zero and preferably ranges between 60 and 120 degrees, more preferably between 80 and 100 degrees, and most preferably extends about perpendicular to the planar web section of the shear web.
  • the connecting element may be configured to comprise (multiple) flanges, stiffening ribs and webs, in addition to the web sections provided by the folded planar web sections of the known relatively flat multi-layered sheet.
  • a connecting element is configured such that the frame stabilizing element comprises a planar web section and flanges for establishing a connection to the primary aircraft structure, whereby the flanges extend at an angle with a plane of the planar web section and at both sides of the plane of the planar web section.
  • a further embodiment of the invention provides a connecting element configured such that a planar web section of the frame stabilizing element and the shear web connect over a distance of at least half the height of the shear web.
  • a connecting element is provided that is configured such that the planar web section of the frame stabilizing element and the shear web connect over a distance substantially equal to the height of the shear web.
  • Another useful embodiment of the invention provides a connecting element that is configured such that a planar web section of the frame stabilizing element comprises a stiffening element along an edge of the planar web section.
  • the stiffening element may be formed integrally with the frame stabilizing element, for instance by injection moulding. It is also possible to make the stiffening element by another method, for instance by pultrusion, and subsequently attach it to the edge of the frame stabilizing element, preferably by bonding.
  • Yet another embodiment relates to a connecting element that is configured such that the wall thickness of the frame stabilizing element and/or of the shear web varies across the element and/or web.
  • the injection moulding method conveniently provides such an embodiment.
  • Another embodiment of the invention provides a connecting element configured such that a web section of the frame stabilizing element and/or of the shear web comprises holes. Holes are conveniently provided in a web section of an element by providing an injection mould with inserts. Reinforcing element may be provided as well, and are preferably selected from the group consisting of a pultrusion element, an extrusion element, a metal insert for receiving a rivet or bolt, a plastic insert for receiving a rivet or bolt and any combination of these.
  • an injection-moulding process for producing a primary structure connecting element is specified.
  • the process has the steps of providing a fibre-reinforced, thermoplastic composition, melting the fibre- reinforced, thermoplastic composition, and injecting the fibre-reinforced, thermoplastic composition into an injection-moulding device.
  • the injection-moulding device has an injection mould for producing the primary structure connecting element.
  • the step of removing the primary structure connecting element produced from the injection-moulding device is included in the process.
  • a lightweight primary structure connecting element can be produced quickly and in one production process with low costs.
  • a fibre -reinforced, thermoplastic composition with a high modulus of elasticity is suitable for this. Further details and aspects with respect to the modulus of elasticity of the fibres used and of the castellation, shear web, clip, frame stabilizing element produced and/or the rib stabilizing element produced are explained below.
  • the fibre-reinforced, preferably thermoplastic, material may be provided in pellet form, and be transported by a transporting device into a heating element.
  • the composition can be melted and compressed, so that it is subsequently injected at the necessary pressure into the cavity, which is formed by the injection mould.
  • 1000 bar may be used as the injection pressure.
  • other values above and below 1000 bar, for example 2000 bar may also similarly be used.
  • the injection mould may be prewarmed or preheated, in order to provide an improved or optimum temperature for a rapid crystallization process. As soon as the matrix has gone over into the solid state, the primary structure connecting element produced can be removed from the injection- moulding device. Since the component produced, i.e.
  • the primary structure connecting element in its final form is covered with the thermoplastic resin, no working, trimming or sealing of the edges of the component produced is necessary. After the completion of the process, resin is respectively present on the surfaces of the moulded primary structure connecting element, so that no fibre lies dry.
  • the fibre-reinforced matrix composition may be provided by providing chopped reinforcing fibers, preferably carbon, graphite and/or glass fibers, in a thermoplastic or thermoset matrix. Various degrees of mixing are possible.
  • thermoplastic composition containing fibre material is provided, melted and injected into an injection-moulding device.
  • a primary structure connecting element (castellation, shear web, clip and/or a frame stabilizing element and/or a rib stabilizing element) to be produced not only at low cost and quickly but also with the required mechanical properties, in particular with regard to its modulus of elasticity.
  • a primary structure connecting element that has been produced by an injection-moulding process and configured in accordance with the invention may comprise a compound having a modulus of elasticity E > 20 GPa , preferably E > 30 GPa, more preferably E > 35 GPa, and most preferably E > 40 GPa.
  • the fibre -reinforced composition comprises discontinuous chopped carbon fibres with a modulus of elasticity Ef > 250 GPa, more preferably Ef > 300 GPa and most preferably Ef > 350 GPa.
  • Suitable matrix materials include thermoset materials like epoxide resins for instance, as well as thermoplastics, like polypolefines and polyamides, high stiffness thermoplastics like polyphenylene sulphide (PPS),
  • PEEK polyetherether ketone
  • PEI polyether imide
  • a preferred connecting element is configured such that it has a (bending) stiffness of between 30 GPa and 40 GPa, 40 GPa and 50 GPa or more preferably greater than 50 GPa.
  • the connecting element in accordance with the invention, as exemplified by the embodiments of the invention.
  • the fibre-reinforced, thermoplastic composition comprises graphite, carbon fibres and/or glass fibres.
  • the use of glass fibers may in certain efficient embodiments of the connecting element be sufficient. Indeed, the configuration of the connecting element may be optimized such that relatively low modulus glass fibers may be used.
  • the injection-moulding process for producing a primary structure connecting element offers the possibility and potential for optimizations with regard to the design and the form of these components and allows an integration of additional stabilizing elements.
  • additional stabilizing elements For example, metal inserts, plastic inserts, extrusion and/or pultrusion elements may be inserted into the injection mould in order to connect it in one working step to the component to be produced. Additional flanges to connect the primary structure connection to the skin may also be included.
  • the fibre- reinforced composition in pellet form, which allows an injection-moulding process to be carried out in practice.
  • the composition is therefore provided in a pellet form and the process also has the step of transporting fibre -reinforced, thermoplastic pellets into a melting device for carrying out the melting.
  • the ratio of the average length L of the fibres to the average diameter d of the fibres in the molded component is L/d > 10, more preferably L/d > 50, even more preferably L/d > 75 and most preferably L/d > 100.
  • the fibres have on average a length of between 0.1 mm and 5 mm. For example, 0.7 mm may be preferred. This may be a mean value about which the lengths of the individual fibres in the composition are randomly distributed. According to a further exemplary embodiment, a mean value of the fibres does not exceed the maximum value of 1 mm, 2 mm, 3 mm, 4 mm or 5 mm.
  • the composition has carbon fibres with a modulus of elasticity E that has a value in a range of E > 250 GPa, E > 300 GPa or E > 350 GPa, and/or the composition has glass fibres with a modulus of elasticity E that has a value of E > 70 GPa, E > 85 GPa or E > 95 GPa.
  • Carbon fibres with such a high modulus of elasticity can be used to injection-mould in particular stiff primary structure connecting elements which absorb the usual loads that occur in the primary structure in an aircraft.
  • Glass fibres are cheaper and, depending on requirements, can be used as a single fibre constituent of the composition or be admixed with the carbon fibres. It should be mentioned that these exemplary embodiments can be combined readily and in particular with the exemplary embodiments described above and below with respect to the length of the fibres.
  • the choice of the injection-moulding technique for producing the aircraft fuselage fastening means i.e. the primary structure connecting element, makes it possible to realize a particular reinforcement in certain regions of the component produced, whereby other regions of the component can for example be made thinner and/or shorter.
  • a combination of an injection-moulding production of the aircraft fuselage fastening means or wing fastening means or fastening means for the tailplane, vertical tail surfaces and horizontal tail surfaces and a reinforcement by means of a pultrusion element or an extrusion element for example is therefore realized.
  • the primary structure connecting element for example the shear web and/or the frame stabilizing element may be combined together with a reinforcing element in a single component by the injection- moulding technique.
  • the injection moulded process also allows to produce primary structure connecting element with flanges in two directions (so-called T-flange) and thereby reinforcing the connection to skin and rib or frame. This configuration is not possible with state of the art technology.
  • a metal insert which has an opening that extends through the primary structure connecting element when the injection-moulding operation has been completed is inserted into the injection-moulding device before the moulding process.
  • the metal insert surrounds this opening of the primary structure connecting element. This opening may be designed for receiving a rivet/bolt for fastening the aircraft skin to the airframe.
  • One or more plastic inserts may also be used alternatively or in combination.
  • a metal or plastic strip may also be provided as reinforcing element allowing support for one or more rivets/bolts.
  • the composition contains polyphenylene sulphide (PPS), polyetherether ketone (PEEK) and/or polyether imide (PEI).
  • PPS polyphenylene sulphide
  • PEEK polyetherether ketone
  • PEI polyether imide
  • the primary structure connecting elements according to the invention can be used in particular in helicopters, satellites or other transport or fighter aircraft. According to a further exemplary embodiment of the invention, such an aircraft is specified.
  • the primary structure connecting element may also be regarded as an aircraft fuselage fastening means, which is suitable and designed for fastening the aircraft skin to a frame/rib of the airframe or for ribs in the wing (for example at the "tankhole or manhole").
  • aircraft fuselage fastening means suitable and designed for fastening the aircraft skin to a frame/rib of the airframe or for ribs in the wing (for example at the "tankhole or manhole").
  • the primary structure connecting element has a substantially triangular or a triangular structural form. According to a further exemplary embodiment of the invention, the primary structure connecting element has a substantially trapezoidal or a trapezoidal structural form.
  • the primary structure connecting element has at least a first flange for establishing a connection to the aircraft skin and has at least a second flange for establishing a connection to the aircraft skin.
  • the two flanges lie (substantially) in one plane, such as for example the flanges 501 and 511 in Figure 5.
  • the use of the injection-moulding process allows such a component to have two different flanges for fastening to the aircraft skin. This is not possible with previous production methods, particularly not for an integrated component.
  • a specific exemplary embodiment of this is shown in Figure 5 and described.
  • flange 506 is also supplemented with another flange 512 on an opposite side of part 510, the flange 512 extending in the same plane as flange 506. According to the prior-art process, a primary structure connecting element with two flanges cannot be produced, since there the component is folded from a sheet.
  • the present invention makes both possible, however, it is of particular value for primary structure connecting elements with two, three, four or more flanges.
  • a primary structure connecting element with differences in wall thickness may also be provided alternatively or in combination by the present invention.
  • the primary structure connecting element comprises a compound with a modulus of elasticity E that has a value in a range of 20 GPa ⁇ E ⁇ 60 GPa. It needs to be mentioned that application of the additional stiffening elements allows for lower values of the compound elastic modulus, if desired.
  • the primary structure connecting element has a reinforcing element that is selected from the group consisting of a pultrusion element, an extrusion element, a metal insert or an insert of plastic for receiving a rivet/bolt (or more rivets & bolts) and any combination of these.
  • the primary structure connecting element has at least a first, a second, a third and a fourth flange.
  • an aircraft that has a primary aircraft structure with at least one frame and at least one rib and an aircraft skin is specified. It also includes a castellation or a shear web or a clip, a frame stabilizing element and a rib stabilizing element. A first part of the aircraft skin is fastened to the frame of the primary aircraft structure and a second part of the aircraft skin is fastened to the rib of the primary aircraft structure. Furthermore, the first part of the aircraft skin is fastened to the frame of the primary aircraft structure by means of the shear web or the clip and the frame stabilizing element, and the second part of the aircraft skin is fastened to the rib of the primary aircraft structure by means of the rib stabilizing element.
  • At least one element from the group consisting of the castellation or shear web, the clip, the frame stabilizing element and the rib stabilizing element is produced from a fibre-reinforced, thermoplastic composition by means of injection moulding.
  • Figure 1 shows a flow diagram of an injection-moulding process for producing a shear web, clip, frame stabilizing element and/or a rib stabilizing element according to an exemplary embodiment of the invention
  • Figure 2 shows a detail from a primary aircraft structure with a plurality of primary structure connecting elements according to an exemplary embodiment of the invention
  • Figure 3 shows a primary aircraft structure with a multiplicity of shear webs and frame stabilizing elements according to a further exemplary embodiment of the invention
  • Figure 4 is a schematic representation of a primary structure connecting element which has as an integrated solution both a clip and a frame stabilizing element or a clip and a rib stabilizing element according to an exemplary embodiment of the invention
  • Figure 5 is a schematic representation of a primary structure connecting element which additionally has as an integrated solution reinforcing elements according to an exemplary embodiment of the invention
  • Figure 6 is a schematic representation of a typical installation location of a shear web and a frame stabilizing element according to a further exemplary embodiment of the invention.
  • Figure 7 is a schematic representation of an aircraft according to a further exemplary embodiment of the invention.
  • Figure 1 represents an injection-moulding process according to an exemplary embodiment of the invention by means of a flow diagram in which the steps SI, S2, S3 and S4 are shown.
  • the injection-moulding process is used for producing a primary structure connecting element (a shear web, clip and/or a rib or frame stabilizing element) and uses a fibre -reinforced thermoplastic composition as the injection-moulding medium.
  • This composition is provided in step SI.
  • the fibre-reinforced, thermoplastic composition lati larton k/40 hm, or lati larpeek 1 Ok/40 hm may be used for example.
  • step S3 the molten composition can be injected into an injection-moulding press with an injection mould for producing the primary structure connecting element.
  • one or more gates are provided in the injection mould at preselected positions. These positions depend for instance on the particular shape of the element to be injection moulded, on the primary loads to be transferred, the specific injection moulding process to be applied and other factors, but one skilled in the art of injection moulding will be able to select the positions such that at least part of the discontinuous fibres are oriented along paths of primary load transfer.
  • step S4 the primary structure connecting element produced can be removed or ejected, so that a further cycle of the injection-moulding process can be carried out.
  • a castellation or a shear web or clip or a frame stabilizing element or a rib stabilizing element can be produced.
  • the corresponding injection mould should be used for this.
  • injection-mould an integrated variant that includes both a shear web and a frame stabilizing element should be regarded as a special embodiment of the invention, two exemplary embodiments being shown in Figures 4 and 5.
  • the injection-moulding process shown in Figure 1 may be supplemented by additional steps in exemplary embodiments that are taken further.
  • Pellets of plastic i.e. the fibre- reinforced, thermoplastic composition
  • Pellets of plastic are loaded into a container by means of a screw pump.
  • the pellets of plastic are melted by means of heating elements.
  • the molten pellets of plastic are injected into the moulding device by means of the screw.
  • An increase in pressure of up to 2000 bar may be used for this.
  • the cold mould causes the molten pellets of plastic to solidify and go over into the solid state.
  • the moulded primary structure connecting element can be removed.
  • the temperature is dependent on the mould that is used. It may be 250°C to 400°C or else less than 250°C or greater than 400°C.
  • FIG. 2 is a schematic representation of part of an primary aircraft structure 200 in the main fuselage area of an aircraft, in which multiple frames 205 and 206 are shown. Such an aircraft is represented for example in Figure 7. Similarly shown are multiple stringers 207 and 208, which are fixedly connected to the two frames shown.
  • a primary structure connecting element a multiplicity of castellation's, shear webs and clips 201 and 202, which are fastened to the respective frame by rivets and/or bolts.
  • the castellation's or shear webs 201 and 202 have been produced from a fibre- reinforced, thermoplastic composition by means of injection moulding.
  • the frame stabilizing elements (cleats) 203, 204 which similarly consist of a fibre -reinforced, thermoplastic material and have been produced by means of injection moulding, as described herein.
  • the frame stabilizing elements 203 and 204 shown in Figure 2 have chopped glass and/or carbon fibres, which have an average length of between 0.1 mm and 5 mm. For other applications, shorter and/or longer fibres may also be used without departing from the scope of the invention.
  • the longitudinally extending stringers 208 are connected to the frames 205 and 206 both by way of the castellation's or shear webs and clips 201, 202 and moreover by way of the frame stabilizing elements 203 and 204.
  • the aircraft skin of the associated aircraft is connected to the primary structure 200 by way of the elements 201, 202, 203 and 204. At the same time, the aircraft skin is not shown here. Riveted connections and/or bolts are used in particular for this.
  • a plurality of primary structure connecting elements that are arranged in a primary aircraft structure 300 are shown in Figure 3.
  • two frames 307 and 308 that extend in the form of an arc of a circle are represented in Figure 3.
  • Multiple longitudinally extending stringers 309 can be seen in Figure 3.
  • multiple shear webs and clips 301, 302 and 303 and also multiple frame stabilizing elements 304, 305 and 306 are shown.
  • Each frame stabilizing element 304, 305 and 306 extends substantially perpendicularly away from the frame 307, to be precise perpendicularly from the direction running in the form of an arc of a circle.
  • the shear webs 301, 302 and 303 extend parallel to the face 310 of the frame 307 that extends perpendicularly to the longitudinal direction of the aircraft.
  • the longitudinal direction of the aircraft is represented in Figure 3 by the arrow 311.
  • the clips and cleats may be connected to the aircraft skin by riveting with riveted connections or by means of bolts (Hi-Loks, Hi-Lites or lockbolts).
  • a primary structure that uses ribs that is to say for example in wings, vertical tail surfaces or horizontal tail surfaces, is specified by analogy with Figures 2 and 3.
  • the invention also relates to the rear fuselage area, in which integral frames are used.
  • castellation's or shear webs 201, 202 and rib stabilizing elements 203 and 204 which are produced by means of injection moulding and from a fibre -reinforced, thermoplastic composition, are then used on the ribs of the aircraft. Since such ribs are known to a person skilled in the art, a further description is not necessary.
  • Figure 4 shows a primary structure connecting element 400, which has as an integrated solution both a clip and a frame stabilizing element or a clip and a rib stabilizing element.
  • Element 400 has both a first component region 401, which is designed as a clip and can be used as such, and a second component region 402, which is designed as a frame stabilizing element and can be used as such. Between these two regions 401 and 402 there is a planar transitional region 403, so that a common flange is formed for the clip 401 and the frame stabilizing element 402.
  • This integral solution which combines a shear web and a frame stabilizing element in one component, is produced by the injection-moulding process according to the invention.
  • the primary structure connecting element shown in Figure 4 consists of a fibre-reinforced, thermoplastic material and has a stiffness, i.e. a modulus of elasticity, that is greater than 40 GPa.
  • carbon fibres in a chopped form have been used together with PPS as the thermoplastic composition.
  • PPS polystyrene
  • the following materials have proven to be suitable for the injection-moulding process according to the invention for producing aircraft shear webs and aircraft frame stabilizing elements. Fibres in a chopped form, for example with a length/maximum length of 0.1 mm to 5 mm, are suitable. Lenghts other than these of the fibres are also possible.
  • such long carbon fibres may be used with polyphenylene sulphide (PPS), polyetherether ketone (PEEK) and/or polyether imide (PEI) as the fibre-reinforced, thermoplastic composition.
  • PPS polyphenylene sulphide
  • PEEK polyetherether ketone
  • PEI polyether imide
  • the primary structure connecting element 400 has a first two-dimensional region 404, which is designed to be fastened parallel to the main direction of extent of an aircraft frame to said frame. Such fastening can be seen for example from Figure 6.
  • a two- dimensional region 405 extending substantially perpendicularly thereto is designed as a first flange for the purpose of being fastened in its installed position of the primary aircraft structure to a stringer, such as for example the stringers 606 in Figure 6.
  • the component region 402 has a substantially triangular region 407, which serves as a frame stabilizing element. Substantially perpendicular to this triangular region 407, a first upper region 408 extends in a perpendicular direction in relation to the plane of the region 407.
  • the first upper region may be regarded as a flange for fixing to an aircraft frame/to an aircraft rib.
  • the component 400 can thereby also be fastened in the region 408 to a frame 601.
  • this region 402 extends in the lower part almost perpendicularly into a two-dimensional region 409, by means of which the frame stabilizing element 402 can be fastened to the stringer foot, for example stringer 606 in Figure 6.
  • the clip-cleat combination 400 is also referred to by a person skilled in the art as simply a clip.
  • Figure 5 shows a primary structure connecting element 500, which by analogy with Figure 4 has both a region that can be used as a clip and a region that can be used as a frame stabilizing element/rib stabilizing element.
  • the exemplary embodiment of Figure 5 has multiple reinforcing elements 501, 502, 503, 504, 505, 507 and 512.
  • the reinforcing elements described below can also be used individually and in any desired combination, if desired, on a clip or shear web or on a frame stabilizing element.
  • the primary structure connecting element that can be produced by the injection-moulding process can be specifically optimized by means of different reinforcing elements and/or different wall thicknesses.
  • Element 501 represents an additional, second flange, which can be realized on the primary structure connecting element 500 by means of the injection-moulding process of the present invention in a simple and low-cost way in one moulding step. Furthermore, it is possible to carry out the injection-moulding process in such a way that a rib 502 is arranged on the element 500. The possibility of being able to carry out the injection- moulding process relatively quickly means that relatively complex supplemental mouldings of the primary structure connecting element can be integrated thereby. It is similarly possible, as an additional or supplemental measure, to insert a metal insert or plastic insert 503 into the injection-moulding device, so that there are correspondingly reinforced rivet positions in the component 500 thereby produced.
  • a strip can be applied which contains the (rivet/bolt) holes.
  • a reinforcement 504 around a hole or a clearance 509 may be included, so that an overall weight saving is obtained for the region 510, but no sacrifices have to be made with regard to the necessary mechanical stiffness.
  • Figure 5 shows furthermore that the stiffening element 505, which may be formed for example as a pultrusion element and/or as an extrusion element, has been arranged locally along an edge. Such pultrusion and/or extrusion elements may similarly be inserted into the moulding device at the desired location, in order subsequently to obtain a one-part component.
  • the injection- moulding technology used makes it possible that variations in thickness are possible locally, which is shown for example as an increase of the wall thickness in the regions 506, 507 and locally in the radius 508 in Figure 5. A reduction of the wall thickness can also be performed very easily for the user on account of the use of the injection-moulding technique.
  • the gap between 404 and 408 in Figure 4 cannot be avoided at present by the prior-art process.
  • the injection-moulding process according to the invention can close this gap, if desired, as is shown in Figure 5. Elements 506 and 507 are connected there. This significantly increases the stability of the clip-cleat combination, as shown in Figure 5. The same applies to the two flanges 501 and 502.
  • FIG. 6 shows part of a primary aircraft structure 600, on which a shear web 605 and a frame stabilizing element 602 are arranged. This is a shear web 605 because this component extends over a number of stringers and does not only extend from a first stringer to a second stringer like a clip.
  • a frame 601 and also a stringer 606 are also represented in Figure 6.
  • the frame stabilizing element i.e. the cleat or stabilizer, is of a substantially triangular design here and has two fastening regions 607 and 608 that are perpendicular to this triangular plane.
  • the cleat 602 is fastened to the stringer by means of rivets/bolts 603.
  • rivets/bolts are used to connect the cleat 602 fixedly to the frame 601 in the region 607.
  • the shear web 605 (by means of introducing shear in a frame) has a first larger main area 609, which is fastened flat against the frame 601 by means of rivets/bolts 604.
  • a second region 610, extending perpendicularly thereto, is similarly included in the shear web 605 as a flange, by means of which the clip can be fixed by riveting to the skin/stringer located under it.
  • the primary aircraft structure is represented by way of example in Figure 6 by the frame 601 and the stringer 606.
  • the frame stabilizing element 602 can be riveted/connected by bolts directly onto the stringer, to which the aircraft skin is then in turn riveted or adhesively bonded.
  • the rivets/bolts are fastened into the fastening region 608.
  • the stringer and the skin in this case form an integral component.
  • the frame stabilizing element 602 may also be arranged such that the fastening region 608 lies directly on the skin and the rivets/bolts reach through the stabilizing element and through the skin. This can also be applied to all of the exemplary embodiment of the invention, and other ways of attaching the aircraft skin to the primary structure are not ruled out either.
  • Figure 7 shows an aircraft 700, which has a first part of the aircraft skin 701 in the main fuselage area.
  • the aircraft skin 701 is fastened to a primary aircraft structure, such as that described above, by means of multiple shear webs and/or multiple frame stabilizing elements.
  • the shear webs used and/or the frame stabilizing element have been produced from a fibre -reinforced, thermoplastic material by an injection-moulding technique, which leads to the aforementioned advantages for the user.
  • the second part of the aircraft skin 703 is attached to the wing 702, ribs being arranged here in the primary structure, for which reason rib stabilizing elements are used here.
  • a third part of the aircraft skin (704, 705) is attached to the rear fuselage section (706) with vertical and horizontal tail surfaces (tailplane), ribs being arranged here in the primary structure, for which reason rib stabilizing elements are used here.
  • Figure 7 shows according to a further exemplary embodiment of the invention an aircraft that has a primary aircraft structure with multiple frames and multiple ribs and an aircraft skin.
  • multiple castellation' s or shear webs, clips, frame stabilizing elements and rib stabilizing elements are included in the aircraft.
  • the first part of the aircraft skin is fastened to the frames of the primary aircraft structure by means of the shear webs and the frame stabilizing elements and the second part of the aircraft skin is fastened to the respective ribs of the primary aircraft structure by means of shear webs and rib stabilizing elements.
  • at least one castellation or shear web, a clip, a frame stabilizing element or a rib stabilizing element has been produced from a fibre -reinforced, thermoplastic composition by means of injection moulding, as described herein.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Connection Of Plates (AREA)

Abstract

L'invention concerne un élément de raccordement destiné à fixer un revêtement d'aéronef à un élément de renforcement primaire d'aéronef. L'élément de raccordement comprend une âme de cisaillement et, formé d'un seul tenant avec elle, un élément de stabilisation de châssis. L'élément de raccordement comprend une composition renforcée par des fibres faite de fibres discontinues en un matériau de matrice thermoplastique ou thermodurcissable, il est conçu pour transférer des charges primaires entre le revêtement d'aéronef et le châssis principal d'aéronef et il est caractérisé en ce qu'au moins une partie des fibres discontinues est orientée de manière intentionnelle et contrôlée le long de parcours de transfert des charges primaires. L'invention concerne également un aéronef doté d'un élément de raccordement de structure primaire en vue de la fixation du revêtement d'aéronef à la structure primaire de l'aéronef. L'élément de raccordement de structure primaire est, de préférence, produit à partir d'une composition renforcée par des fibres au moyen de moulage par injection. On utilise notamment pour cet usage des fibres hachées de graphite et carbone et/ou des fibres de verre incorporées dans un matériau de matrice, par exemple sous forme de granules.
PCT/NL2015/050170 2014-03-17 2015-03-17 Élément de raccordement de structure primaire pour aéronef et procédé de fabrication de l'élément de raccordement WO2015142171A1 (fr)

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Application Number Priority Date Filing Date Title
EP15715492.3A EP3119577A1 (fr) 2014-03-17 2015-03-17 Élément de raccordement de structure primaire pour aéronef et procédé de fabrication de l'élément de raccordement

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NL2012457 2014-03-17
NL2012457A NL2012457B1 (en) 2013-07-16 2014-03-17 Primary structure connecting element for aircraft and method for manufacturing the connecting element.

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WO2015142171A1 true WO2015142171A1 (fr) 2015-09-24

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CN108082474B (zh) * 2017-10-31 2022-11-18 中航通飞华南飞机工业有限公司 一种水上飞机断阶框结构

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