Abstract
A composite element and a method of manufacturing the same. The composite element comprises a first skin plate and second skin plate, which are manufactured as separate pieces and are assembled in a separate phase. At least the first skin plate comprises several protrusions on an outer surface of the plate. The protrusions serve as local stiffeners and are further stiffened by means of one or more additional composite structures arranged inside the protrusions.
Claims
1. A composite element comprising: a first skin plate and a second skin plate, which are both prefabricated composite elements comprising basic composite structure; inner surfaces and outer surfaces of the skin plates, and wherein the inner surfaces are fastened permanently to the composite element structure; at least the first skin plate comprises several protrusions on the outer surface of the first skin plate for providing it with local stiffeners; several additional first composite structures attached to the first skin plate only at the locations of each of the mentioned protrusions; and wherein the additional first composite structures form inner stiffeners at the protrusions and are covered by the basic composite structure of the first skin plate on the outer surface side of the composite element; wherein the first skin plate and the second skin plate are formed by laminating technique; at least one of the mentioned additional first composite structures are laminated on the inner surfaces of the first skin plate; and and the basic composite structure of the first skin plate and the first additional composite structure attached on an inner surface of the first skin plate are being bulged together at the protrusions.
2. The composite element as claimed in claim 1, wherein each of the protrusions have elongated fold-like configurations on the outer surface side and comprise the additional first composite structures arranged between folded layers of the basic composite structures of the protrusions, whereby the additional first composite structures form inner material layers between the layers of the folded basic composite structures.
3. The composite element as claimed in claim 1, wherein each of the additional first composite structures inside the protrusions comprise two composite material layers being folded against each other, whereby the folded additional first composite structures have a double layer structure.
4. The composite element as claimed in claim 1, wherein the additional first composite structures form central stiffeners inside the protrusions, whereby the protrusions and the additional first composite structures protrude transversally relative to the outer surface of the first skin plate.
5. The composite element as claimed in claim 1, wherein each of the protrusions and the additional first composite material forming the inner stiffeners of the protrusions comprise at least one transversal portion having transversal direction relative to central axis of the protrusions.
6. The composite element as claimed in claim 1, wherein at least some of the protrusions of the first skin plate are provided with inner spaces free of composite material; and and inner surface portions of the first skin plates limiting the inner spaces of the protrusions are provided with the additional first composite structure for stiffening the protrusions.
7. The composite element as claimed in claim 1, wherein the composite element further comprises: several additional local second composite structures arranged to the second skin plate only at the locations of each of the protrusions.
8. The composite element as claimed in claim 1, wherein the composite element is a component of an aircraft.
9. The composite element as claimed in claim 1, wherein the outer surface of the second skin plate is mounted against a surface structure or third skin plate made of material other than composite material.
10. A method of manufacturing a composite element, wherein the method comprises: forming a first skin plate and a second skin plate of composite material both comprising at least one binder material and at least one reinforcing material; arranging several local first additional composite structures on an inner surface of the first skin plate, whereby the inner surface comprises integrated additional structures at a distance from each other; bulging the first skin plate locally towards an outer surface side at the locations of first additional composite structures for forming protrusions on the side of the outer surface; attaching the inner surface of the first skin plate permanently against the second skin plate; and curing the composed structure; wherein the method further comprises forming the first skin plate and the second skin plate by laminating technique; laminating the mentioned additional first composite structures on the inner surfaces of the first skin plate; and and bulging the basic composite structure of the first skin plate and the first additional composite structure attached on an inner surface of the first skin plate together at the protrusions.
11. The method according to claim 10, comprising compressing the bulged protrusions in the transverse direction relative to central axis of the protrusions for setting surfaces of the bulged first additional structures against each other at the protrusions.
12. The method according to claim 10, comprising shaping the formed protrusions of the first skin plate additionally by providing the protrusions with one or more bent portions.
13. The method according to claim 10, comprising inserting a prefabricated composite profile inside each of the bulged protrusions of the first skin plate; and pressing the basic composite structure and the additional first composite structure together towards the inserted composite profile, whereby the basic component structure of the protrusion and the inner stiffener formed by the additional first composite structure are both shaped in accordance with the shape of the inserted composite profile.
14. The method as claimed in claim 10, comprising forming a multi-material structure by mounting the outer surface of the second skin plate permanently against a third skin plate or surface made of material other than the composite material.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0054] Some embodiments of the invention will be explained in greater detail in the attached drawings, in which
[0055] FIG. 1 shows schematically part of an aircraft, the structure of which may comprise the disclosed planar and curved composite elements,
[0056] FIG. 2 shows schematically a tail of an aircraft, the structure of which tail may comprise the disclosed composite elements,
[0057] FIGS. 3 and 4 show schematically a top view and a side view of a prior art composite element comprising several separate stiffening components fastened on its outer surface,
[0058] FIG. 5 is a schematic top view of an inner surface of a first skin plate of a composite element after its basic composite structure has been laminated, and FIG. 6 shows the inner surface after additional first composite layers have been laminated at positions of protrusions which are to be formed,
[0059] FIG. 7 is a schematic top view of an inner surface of a second skin plate of the composite element after being provided with additional second composite layers at positions of protrusions of the first skin plate,
[0060] FIG. 8 is a schematic view of a detail showing a principle of bulging process and forming protrusions by means of movable mould elements,
[0061] FIG. 9 is a schematic view of a detail showing compressing phase, wherein the bulge of FIG. 8 is compressed in transverse direction by means of pressing tools,
[0062] FIG. 10 is a schematic side view of a first skin plate after several protrusions have been formed on its outer surface side by means of bulging,
[0063] FIG. 11 is a schematic side view of a first skin plate after the bulged protrusions have been compacted,
[0064] FIG. 12 is a schematic side view of a composite element comprising a first skin plate with protrusions and a second skin plate with an even outer surface,
[0065] FIG. 13 is a schematic side view of a composite element comprising a first skin plate and a second skin plate both comprising protrusions and an intermediate plate between the skin plates,
[0066] FIG. 14 is a schematic view of a curved fuselage component comprising hollow or foam filled protrusions,
[0067] FIG. 15 is schematic view of a protrusion comprising a central inner stiffener having I-shape,
[0068] FIG. 16 is a schematic view of a protrusion comprising a transverse portion at its outer end portion,
[0069] FIG. 17 is a schematic view of a protrusion comprising an enlargement at its outer end,
[0070] FIG. 18 is a schematic view showing that inner stiffeners of a first and second skin plate are combined and form together an inner stiffener having shape of an inverted T,
[0071] FIG. 19 is a schematic view showing that a bent inner stiffener of a first skin plate and a surface stiffener of a second skin plate are combined and form together an inner stiffener having C-shape,
[0072] FIG. 20 is a schematic view showing that an inner stiffener comprising an enlargement is combined with a surface stiffener of a second skin plate,
[0073] FIGS. 21-25 are schematic views of an alternative solution wherein inside a protrusion is arranged a prefabricated composite profile element having T-shape,
[0074] FIGS. 26 and 27 are schematic views of a protrusion provided with a composite profile element having C-shape,
[0075] FIGS. 28 and 29 are schematic views of protrusions provided with inserted profile elements which only serve as inner stiffeners for the protrusions, and
[0076] FIG. 30 is a schematic end view of a hollow beam structure provided with composite stiffening elements on inner surfaces of the beam,
[0077] FIG. 31 is a schematic end view of another hollow beam having composite stiffening elements on its inner and outer surfaces,
[0078] FIG. 32 is a schematic view of a surface of a machine component on which is fastened a composite element comprising a first skin plate provided with several protrusions and a second skin plate, and
[0079] FIG. 33 is a schematic cross-sectional view of a tubular element which is made stiffer by mounting composite stiffening elements on its inner surfaces.
[0080] In the figures, some embodiments of the invention are shown simplified for the sake of clarity. Like reference numerals refer to like parts in the figures.
DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION
[0081] FIG. 1 shows a wing 1 that is fastened to a fuselage 2 of an aircraft. A trailing edge of the wing may comprise movable control surfaces 3a to 3c. The wing 1 may comprise an upper skin plate 4a and a lower skin plate 4b, between which is arranged a support structure for the wing that may comprise a front spar 5, rear spar 6, wing ribs 7 and stringers 8. The composite element disclosed in this patent application may be utilized as a load carrying structural component in the wing 1 or the fuselage 2. The composite element may then be part of the control surfaces 3a-3c, part of the support structure of the wing 1 or part of the fuselage 2.
[0082] FIG. 2 shows a tail of an airplane and comprises fixed stabilizers 12a and 13a, and movable control surfaces 12b, 13b. Support structures of the tail, stabilizers and the control surfaces may comprise composite elements disclosed in this patent application.
[0083] FIGS. 3 and 4 show a prior art composite element 14 which comprises several separate stiffening components fastened on its outer surface 16. The stiffening components 16 may be cured components which are adhesive bonded on a cured composite element in order to form local stiffeners for the composite element 14.
[0084] It should be noted that the following FIG. 5—of this patent application are strongly simplified presentations of the disclosed solution and are simplified for improving clarity.
[0085] FIG. 5 discloses a first skin plate 17 of the disclosed solution. The skin plate 17 may be a substantially rectangular piece made of composite material. Basic composite structure 18 of the skin plate may be laminated and it may comprise one or more binding material 19 and one or more reinforcing material 20.
[0086] FIG. 6 shows that on an inner surface 17a of the first skin plate 17 may be laminated several additional first composite layers or structures 22. The additional composite structures 22 have elongated configuration and their direction may be transverse to longitudinal direction of the composite element. The additional first composite structures 22 have been laminated only at positions of protrusions which are to be formed for the first skin plate 17 in following manufacturing phases. Thereby, between the parallel first composite structures 22 are portions where the basic composite structure 18 forms the outermost surface. The additional first composite structure 22 may comprise different fibre orientation compared to the basic composite structure 18. In FIG. 6 the first additional composite structure 22 comprises only longitudinal reinforcing fibres.
[0087] FIG. 7 shows a second skin plate 23 the shape of which corresponds to the shape of the first skin plate 17, and which may also be formed by laminating technique. On an inner surface 23a of the second skin plate 23 may be laminated several parallel additional second composite layers or structures 24 at positions of protrusions of the first skin plate 17. Width, positioning relative to the protrusions and structure of the additional second composite structures 24 may be selected case by case.
[0088] FIG. 8 discloses in a simplified manner one possible principle of creating protrusions for the skin plate. The first skin plate 17 according to FIG. 6 is positioned on a mould arrangement 25 so that an outer surface of the skin plate is facing against the mould arrangement 25. The first skin plate 17 is fastened immovably to movable mould elements 26a, 26b of the mould arrangement 25. The fastening may be based on vacuum or the first skin plate 17 may be pressed by means of mechanical fastening elements 27. Initially there is a gap 28 between the mould elements 26a, 26b and when the mould elements 26a, 26b are moved towards each other to degrease the gap 28, then the first skin plate is being bulged to the outer surface side at the gap 28. During the bulging the first skin plate 17 is heated by means of a heating device 29. The bulged portion of the skin plate 17 forms then a protrusion 30, wherein the basic composite material 18 as well as the additional first composite structure 22 are both being bulged.
[0089] FIG. 9 shows that the formed bulged portion or protrusion 30 may be compressed by pressing it transversally by means of pressing tools 31 under an elevated temperature. This way the protrusion 30 may be further shaped after the bulging process. The protrusion 30 may be compressed so that no void volume is left inside it and inner surfaces of the additional first composite structure 22 are pressed against each other.
[0090] In FIG. 10 the first skin plate is disclosed after the bulging process and in FIG. 11 after the bulges have been compressed.
[0091] FIG. 12 discloses an assembled composite element 14 comprising a first skin plate 17 with protrusions 30 and a second skin plate 23 with an even outer surface. The inner surfaces 17a, 23a of the skin plates are fastened permanently against each other. At the protrusions 30 are located additional second composite structures 24 of the second skin plate 23. The additional second composite structures 24 may support the folded first composite structures 22 inside the protrusions 30. The additional composite structures 22, 24 may be fastened to each other and may then form combined inner stiffeners. In FIG. 12 the outer surface of the second skin plate 23 is even.
[0092] FIG. 13 shows an alternative for the solution of FIG. 12. The composite element 14 may comprise a first skin plate 17 and a second skin plate 23 both comprising protrusions, and further, one or more intermediate plates 40 may be arranged between the skin plates 17, 23. The intermediate plate 40 may comprise second composite structures 24 for generating local stiffeners at the protrusions 30.
[0093] FIG. 14 discloses a simplified cross-section of a curved composite element 14 intended to be used as fuselage element. The fuselage component may comprise a first skin plate 17 on its inner surface side and a second skin plate 23 on its outer surface side. As can be noted the first skin plate 17 comprises protrusions 30 in the longitudinal direction of the fuselage. The protrusions 30 comprise inner stiffeners on their inner surfaces. The inner stiffeners may be additional first composite layer or structures 22 laminated on the inner surface 17a of the first skin plate and being bulged together with the basic composite structure 18. Inside the protrusions 30 may be void spaces 32a or the spaces may comprise light-weight material 32b. Void spaces can be filled with support tooling material during cure.
[0094] FIG. 15 discloses a protrusion 30 comprising a central inner stiffener 33 having I-shape. The inner stiffener 33 may be formed by the bulging technique disclosed above, whereby it has folded double-layer structure, or alternatively, it may be formed by arranging an insert piece inside the bulge.
[0095] FIG. 16 shows a protrusion 30 comprising a transverse portion 34 at its outer end portion. The transverse portion 34 may be bent after the bulging process or during it. An end part of the protrusion 30 is bent 90°.
[0096] FIG. 17 shows a protrusion 30 comprising an enlargement or bulb 35 at its outer end. An end part of the protrusion 30 is bent 180°.
[0097] FIG. 18 shows that stiffeners 22, 24 of a first and second skin plate 17, 23 are combined and form together an inner stiffener 33 having shape of an inverted T.
[0098] FIG. 19 discloses bending of an end part of the protrusion 30 for forming a transverse portion 34. Further, the bent stiffener 33 of a first skin plate 17 and a surface stiffener 24 of a second skin plate 23 are combined whereby they form together an inner stiffener 33 having C-shape.
[0099] FIG. 20 shows bending of an end part of the protrusion 30 for forming an enlargement 35. FIG. 20 further shows that an inner stiffener 33 comprising the enlargement 35 is combined with a surface stiffener 24 of a second skin plate 23.
[0100] FIGS. 21-25 show an alternative manufacturing principle for creating inner stiffeners inside the protrusions 30. At first a protrusion 30 is formed by means of bulging technique, for example. Thereafter, a composite profile 36 is inserted inside the protrusion 30, as it is shown in FIG. 22. FIG. 23 shows that the basic composite material 18 and the additional first composite layer or structure 22 are pressed towards the inserted composite profile 36 by means of pressing tools 37. Thereby the additional composite layer 22 is set against the outer surface of the composite profile 36. The composite profile 36 is thereby enveloped by the additional composite layer 22 and the basic composite structure 18, as it is shown in FIG. 24. FIG. 25 still shows that the structure may be assembled and cured by means of vacuum bagging, wherein vacuum is formed by means of a vacuum pump 37 inside a bag surrounding the composed structure. The structure is simultaneously heated by means of a heating device 38. During the curing process the composed structure may be supported by means of additional mould or support pieces 39 for ensuring accuracy of the structure. The additional mould or support pieces 39 may also be used for actively shaping the shape of the protrusion. In this solution the protrusion and the inner stiffener both have shape resembling letter T.
[0101] FIGS. 26 and 27 disclose that a protrusion 30 may be provided with a composite profile element 35 having C-shape.
[0102] FIGS. 28 and 29 discloses alternative solutions wherein profile elements 36 inserted inside the protrusions 30 only serve as inner stiffeners for the protrusions 30.
[0103] FIG. 30 discloses a hollow beam 40 or boom cross-section of which is rectangular. Thus, the beam 40 comprises four walls 41 each of them having outer surfaces 42 and inner surfaces 43. The walls 41 may be of metallic plate material and they may be fastened to each other at corners by weld joints 44, for example. In FIG. 30 the walls 41 are stiffened by mounting composite stiffening elements 14 on their inner surfaces 43. In FIG. 31 also the outer surfaces of the horizontal walls are provided with the disclosed stiffening composite elements 14. Further, as can be noted, the composite elements 14 are fastened against surfaces 42, 43 of the beam 40 via the second skin plates 23.
[0104] FIG. 32 discloses a machine component or structural element 46 on which the composite stiffening element 14 is mounted in order to make the structural element 46 stiffer. The structural element 46 may be of metallic material or any different material as the composite stiffener 14. In FIG. 32 the composite stiffener or element 14 comprises the first skin plate 17 with the protrusions 30 and the additional layers 22 at the protrusions 30. The composite stiffener or element 14 comprises the second skin plate 23 too. The second skin plate 23 of the composite stiffener 14 may be fastened to the surface of the structural element 46 by means of bonding agent 47. The fastening may also comprise mechanical fasteners 48.
[0105] FIG. 33 discloses a tubular element 49, which is composed of two halves 50a, 50b. The tubular element 49 may be made of metallic material, such as steel or aluminum, or other materials like general plastics, thermoset or thermoplastic composite materials. The structure may be stiffened by means of composite stiffening elements 14 mounted against inner surfaces of the halves. In addition to round profiles, other profile shapes, such as ellipse and substantially triangular profiles, may be stiffened in the similar manner.
[0106] In some cases, features disclosed in this application may be used as such, regardless of other features. On the other hand, when necessary, features disclosed in this application may be combined in order to provide various combinations.
[0107] The drawings and the related description are only intended to illustrate the idea of the invention. Details of the invention may vary within the scope of the claims.
