LONG-FIBRE-REINFORCED-JOINTS-COMPOSITE THRUST REVERSER CASCADE

Abstract

Thrust reverser composite cascade (1), comprising at least one longitudinal wall (15) and transverse walls (14) connecting to this longitudinal wall, characterized in that the longitudinal wall comprises at least one continuous longitudinal fibre bundle (19) and the transverse walls each comprise at least one continuous transverse fibre bundle (23) crossing the longitudinal bundle, so that the intersections (16) of the transverse and longitudinal walls are structurally bridged in both directions by the reinforcing continuous longitudinal and transverse fibre bundles.

Claims

1. Thrust reverser composite cascade comprising cells, at least some of them having overhanging shapes, the cascade comprising: at least one longitudinal wall comprising at least one continuous longitudinal fibre bundle with a textile fibre reinforcement architecture, transverse walls connecting to this at least one longitudinal wall, the transverse walls each comprising at least one continuous transverse fibre bundle with a textile fibre reinforcement architecture crossing the longitudinal bundle, so that the intersections of the transverse and longitudinal walls are structurally bridged in both directions by the continuous longitudinal and transverse fibre bundles.

2. Cascade according to claim 1, the bundles incorporating long reinforcing fibres extending in the radial direction.

3. Cascade according to claim 2, comprising long reinforcing fibres extending in the radial direction being oriented at an angle of about 0° or about 45° with respect to the radial direction.

4. Cascade according to claim 2, comprising long reinforcing fibres extending from a lower edge to an upper edge of each transverse wall and each longitudinal wall and between each intersection of the transverse and longitudinal walls.

5. Cascade according to claim 1, each continuous longitudinal fibre bundle and each continuous transverse fibre bundle each having a thickness, in the radial direction, at the intersections of the transverse and longitudinal walls, strictly less than the thickness of the cascade, in the radial direction, at the intersections of the transverse and longitudinal walls.

6. Cascade according to claim 1, the longitudinal and transverse walls crossing each other diagonally or with a variable non-right angle.

7. Cascade according to claim 1, the transverse fibre bundle extending continuously between two outmost lateral longitudinal walls.

8. Cascade according to claim 7, the longitudinal fibre bundle extending continuously from a forward flange to an aft flange.

9. Cascade according to claim 1, comprising a body made of plastic material at least partially covering the fibre bundles so as to form aerodynamic surface geometries.

10. Cascade according to claim 1, comprising fibre bundles at least partially covering a body made of plastic material so as to form aerodynamic surface geometries.

11. Process for manufacturing a composite cascade as defined in claim 1, comprising: Positioning at least one continuous longitudinal fibre bundle and at least one continuous transverse fibre bundle so that the transverse bundle crosses the longitudinal bundle, at least partially covering said bundles with a material to form the body of the cascade.

12. Process according to claim 11, said material being injected into a mould in which said bundles were previously arranged so as to cross.

13. Process according to claim 11, said material being draped around inserts in a mould in which said bundles were previously arranged so as to cross.

14. Process for manufacturing a composite cascade, as defined in claim 1, comprising: forming the body of the cascade by means of a mould, then arranging, by bonding, welding, or any other external process of addition of structural material, at least one continuous longitudinal fibre bundle and at least one continuous transverse fibre bundle so that the transverse bundle crosses the longitudinal bundle.

15. Process according to claim 12, the mould comprising at least one captive insert that cannot be removed from the mould of the cascade because of its shape.

16. Process according to the preceding claim, the captive insert being removed from the cascade by chemical attack, mechanical fragmentation, deformation, melting and/or dissolution.

17. Process according to claim 11, the fibre bundles being manufactured separately from textile fibre reinforcement architectures, and incorporating connecting geometries in order to be tightly fitted together, before being overmoulded or draped, or added externally to a cascade body.

18. Process according to claim 14, the step of arranging at least one continuous longitudinal fibre bundle and at least one continuous transverse fibre bundle being followed by an overmoulding step.

19. Process according to claim 14; the step of arranging at least one continuous longitudinal fibre bundle and at least one continuous transverse fibre bundle being made by additive manufacturing or by wire deposition or by selective laser sintering.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] FIG. 1 schematically represents a substructure of a jet engine nacelle equipped with thrust reverser cascades according to the invention.

[0077] FIG. 2 illustrates, in the finished elements, the deformations of the forward and aft frames leading to the deformations of the forward and aft flanges of a cascade during a reverse thrust action.

[0078] FIG. 3 illustrates on its own a long-fibre-reinforced-joints-composite thrust reverser cascade.

[0079] FIG. 4 schematically represents examples of crossing of bundles in a cascade.

[0080] FIG. 5 is a schematic view illustrating the crossings of reinforcements of a set of cascade reinforcements.

[0081] FIG. 6 illustrates a step of the manufacturing process.

[0082] FIG. 7 illustrates another step of the manufacturing process.

[0083] FIG. 8 illustrates another step of the manufacturing process.

[0084] FIG. 9 illustrates another step of the manufacturing process.

[0085] FIG. 10 illustrates another step of the manufacturing process.

[0086] FIG. 11 illustrates another step of the manufacturing process.

[0087] FIG. 12 is a partial longitudinal cross section of the overmoulded cascade.

[0088] FIG. 13 is a partial radial cross section of the cascade with reinforced joints, at a joint obtained by reinforcement overmoulding.

[0089] FIG. 14 is a partial radial cross section during the step illustrated by FIG. 6 of the process for manufacturing a variant of the cascade with reinforced joints, at a joint obtained by reinforcement draping.

[0090] FIG. 15 is a partial radial cross section view of overmoulded reinforcements,

[0091] FIG. 16 schematically shows examples of long reinforcing fibres extending in the radial direction in bundles in a cascade, and

[0092] FIG. 17 illustrates bundles of various thicknesses (radial dimensions) extending in the radial direction at crossing of bundles in a cascade.

DETAILED DESCRIPTION

[0093] FIG. 1 shows a simplified representation of a substructure of the nacelle of a jet engine equipped with a cascade thrust reverser 1. The nacelle substructure contains a forward frame 4, an aft frame 5, an upper beam zone 6, called 12 o'clock beam, a lower beam zone 7, called 6 o'clock beam, a central location 8 for installation of the parts of the jet engine. The nacelle supports a mechanism 9 that is known in itself that makes it possible to block a part of the air flow entering into the jet engine to return it through the cascades 1 and forward in order to generate a counter-thrust.

[0094] The cascades 1 are disposed around the longitudinal axis 10 of the jet engine and held fastened to the forward 4 and aft 5 frames by forward 2 and aft 3 cascade flange fasteners, and have aerodynamic shapes chosen so as to return the air flow on accurate paths. In FIG. 2, superposed individually are the partial views modelled on the finished elements of a cascade 1 fastened to the front 4 and aft 5 frames not subject to any strain, and the same nacelle parts undergoing deformations due to the mechanical work of a reverse thrust. The bending and unbending deformation 11 of the forward frame is relatively small compared to the bending and unbending deformation 12 of the aft frame, leading to the creation of a forward-to-aft increasing gradient of bending or unbending deformation 13 of the attached cascades.

[0095] FIG. 3 shows an example of cascade 1 on its own.

[0096] The latter has a shape that is generally elongate along a longitudinal axis 10, parallel to the axis of propulsion of the propulsive unit formed by the jet engine and its nacelle.

[0097] The cascade 1 comprises, at its periphery, two, forward 2 and aft 3 flanges, intended for the fastening of the cascade 1 in the nacelle substructure of FIG. 1, and has, for example, a generally rectangular form as illustrated.

[0098] The cells 60 of the cascade 1, which define the air guiding channels, are formed by longitudinal walls 15, hereinafter called strongbacks, which extend in the longitudinal direction, and transverse walls 14 which extend transversely to strongbacks 15. The channel of each cell can thus have a section, generally of polygonal shape, notably square or rectangular, that is offered to the exit air flow.

[0099] The intersections of the longitudinal 15 and transverse 14 walls constitute the joints which can be divided into two categories: on the periphery of the cascade, the T-joints, 17, such that one of the intersecting walls does not cross the other, and, at the centre of the cascade, the X-joints, 16, such that the intersecting walls mutually cross. According to the invention, these X-joints, 16, are bridged structurally in both directions by long-fibre reinforcements.

[0100] FIG. 4 shows several examples of crossings of longitudinal bundles 19 and of transverse bundles 23 that make it possible to reinforce an X-joint 16 zone. For example, two continuous longitudinal bundles 19 extend between two transverse bundles 23, which cross them respectively above and below the level of the zone of the X-joint 16. For example, a single continuous longitudinal bundle 19 extends above a single transverse bundle 23 which crosses it below at an X-joint zone, 16. For example, these last two bundles, longitudinal 19 and transverse 23, are subparts of two continuous, longitudinal 18 and transverse 21, long-fibre reinforcements, machined to be tightly fitted at an X-joint zone, 16.

[0101] According to one aspect of the invention, the cascade 1 comprises a set of reinforcing fibres, represented individually and partially in FIG. 5, comprising longitudinal fibre bundles 19 which cross with transverse fibre bundles 23. This set of FIG. 5 is covered within the cascade at least partially by a skin of plastic material which constitutes the body of the cascade. The body of the cascade has aerodynamic profiles at the cell level.

[0102] The continuous longitudinal bundles 19 are formed by long fibres and extend over all the length of strongbacks 15 from the forward flange 2 to the aft flange 3. Likewise, the continuous transverse bundles 23 are formed by long fibres and extend over all the length of the transverse walls 14, joining the lateral outer contours of the cascade 1.

[0103] As visible on FIG. 16, the longitudinal bundles 19 and the transverse bundles 23 may incorporate long reinforcing fibres 50 arranged in order to form an angle of about 0° with the radial direction R.

[0104] The longitudinal bundles 19 and the transverse bundles 23 can also incorporate long reinforcing fibres 51 arranged in order to form an angle of about 45° with the radial direction R.

[0105] The fibre bundles 19 and 23 are preferably formed with carbon fibres, but other reinforcing materials can be used in place of carbon and/or mixed therewith, such as Kevlar, glass, linen, etc.

[0106] As can be seen in FIG. 5, the bundles 19 and 23 cross at the intersection of strongbacks 15 with the transverse walls 14 of FIG. 3.

[0107] The crossing of the bundles 18 and 21 is performed for example by arranging these bundles at different heights within the cascade 1, as illustrated by the exploded view of FIG. 5. For example, FIG. 5, the exploded view of the reinforcements of the cascade 1, contains a level of strongback reinforcements 18 with discontinuous leading edges 20 and continuous trailing edges 19, crossed with a level of vane reinforcements 21 with continuous leading edges 23 and discontinuous trailing edges 22. In this example, the partial discontinuities of the reinforcements 18 and 21 are useful to the crossing of their longitudinal and transverse bundles by fitting them together. The height of the continuous part of the strongback reinforcement 18 at all points complements the height of the continuous part of the vane reinforcement 21. The aft-to-forward collection of the counter-thrust loads justifies the increasingly small forward-to-aft proportion of the height of passage reserved for the strongback bundles. The increasingly great forward-to-aft height of the continuous vane reinforcements indicates an increasing resistance to the deflexion of the aft frame. The choice of keeping the continuity of the concave leading edge of the reinforcement 21 indicates that it is the resistance to unbending which is helped. In fact, upon a spreading of the frame 5, the concave edge of the reinforcement 21 is subject to tensile and shear stresses that are detrimental to the adhesive interfaces, while the convex edge of the reinforcement 21 is subject to compression and shear stresses that are less detrimental to the adhesive interfaces. A second example of set of reinforcements is obtained by simply exchanging, for each reinforcement, the positions of the continuous and discontinuous edges of FIG. 4. In the case where the cascade 1 is positioned at a point of the frame 5 where the resistance to bending is more necessary, the discontinuities of the reinforcements 18 are inversely positioned on the trailing edge side, and the discontinuities of the reinforcements 21 are inversely positioned on the leading edge side. In fact, the bending consists in bending the frame 5, which is equivalent to reversing the positions of the tensile and compression stresses by comparison to unbending case. Contrary to the first example of arrangement of reinforcements of FIG. 5 in which the vane reinforcements 21 are fitted into the strongback reinforcements 18 from bottom, in the case of this second example of arrangement of reinforcements which will be used in FIGS. 6 to 11 to illustrate an example of manufacturing process, the vane reinforcements 30 are fitted into the strongback reinforcements 29 from top.

[0108] Each longitudinal bundle 19 and each transverse bundle 23 may each have a thickness, in the radial direction R, at the intersections 16 that is strictly less than the thickness of the cascade 1, in the radial direction R, at the intersections 16.

[0109] As visible on FIG. 17, the thicknesses in the radial direction R of the longitudinal bundles 19 and of the transverse bundles 23 may be different while keeping the same thickness of the cascade 1 in the radial direction R at the intersections 16.

[0110] The bundles or long-fibre reinforcements which incorporate them can be given various shapes and/or orientations drawn from these two examples.

[0111] The fibres of the bundles can be bonded by or coated with a plastic material, notably thermoplastic, and each bundle is for example present within a preform. The cohesion of the different fibres of the bundle within the preform is for example obtained by the local melting of a matrix of thermoplastic material coating the fibres.

[0112] An example of process for manufacturing a cascade 1 will now be described with reference to FIGS. 6 to 14.

[0113] For simplification, the manufacture of certain reinforced cascade joints, i.e. the X-joints, will be described, it being understood that the T-joints are not reinforced by fibres but sized by the necessary adhesive interface surfaces.

[0114] The cascade 1 in this example comprises nine strongbacks 15 and twelve transverse vanes 14, among which the ten transverse vanes 14 at the centre form X-joints 16 with strongbacks 15.

[0115] To produce the cascade 1, a mould 25 such as that illustrated in FIGS. 6 to 11 can be used, comprising a mould cavity 27 in which inserts are arranged, including at least one first row of inserts 26 and one second row of inserts 26, visible notably in FIG. 9.

[0116] The inserts 26 define between them, within the cavity 27, spaces for receiving the first level of longitudinal bundles 29, as can be seen in FIG. 6.

[0117] The inserts 26 are progressively put in place, row by row, after the insertion of the bundles 29 or 30. Each bundle 29 or 30 can be put in place by robotized means, as can the inserts 26. The latter can comprise fittings which ensure a predefined positioning within the mould by means of a mechanical fitting, such as, for example, by using retractable guiding and locking fingers 28 at the bottom of the mould cavity 27. In a variant in FIG. 14, the inserts 26 are draped with thermoplastic or thermosetting material 32, such that the body of the cascade is completed upon the installation of the inserts 26 in the mould 25.

[0118] In FIG. 6, a first row of inserts 26 can be seen, in which there is placed a transverse bundle 30, as illustrated in FIG. 7. Then, a new row of inserts 26 is put in place so as to cover the transverse bundle 30, as illustrated in FIG. 8. A new transverse bundle 30 can be installed, as illustrated in FIG. 9, before being covered by a new row of inserts 26, to culminate in the configuration represented in FIG. 10.

[0119] Once all the bundles 29 and 30 have been put in place, the thermoplastic material constituting the body 31 of the cascade 1 is injected into the cavity 27 of the mould 25 modified by the presence of the inserts 26 of FIG. 11, and partially occupied by the reinforcements 29 and 30, to culminate in the mould filled with material 31 as illustrated in the enlargements of sections of FIGS. 12 and 13. The injection of the plastic material can be performed through several channels. As illustrated by the cross-sectional view of overmoulded reinforcements in FIG. 15, if necessary, positioning shims 33 are used to hold the bundles at a certain distance from the walls of the inserts 26 and of the mould 25, for example 1 mm. These shims 33 are for example elements in ball, cylinder or cube form, and can be incorporated in the preform 30 during the manufacture thereof. The preforms 30 can also be of variable thickness and contain provisions for fastening systems such as holes 34 allowing the material 31 to form a fastener.

[0120] The plastic material injected into the mould is for example chosen from among the families of thermoplastics such as polyaryletherketones, polyetherimides, or from among the thermosets, possibly reinforced by carbon, glass, linen or other fibres.

[0121] Prior to the injection of the plastic material into the mould, it is possible, if necessary, to initially heat the mould so as to allow the material forming the matrix of the preforms to melt, in order to obtain a better cohesion of the preforms with one another, at their crossings in particular.

[0122] After the injection, the mould can undergo a slow post-curing in order to fuse the matrix of the preforms with the material forming the body of the cascade.

[0123] The form of the cavity 27 can be such that the cascade 1 can be removed easily from the mould 25. If necessary, the latter is produced in several parts to facilitate this removal from the mould.

[0124] At least a part of the inserts 26 can remain captive in the cascade 1 after the extraction thereof from the mould 25, because of the presence of overhanging shapes at the cells 60 of the cascade.

[0125] The removal of the inserts 26 from the mould can be performed in various ways, depending on the technology retained to allow the removal of the insert.

[0126] For example, inserts are used that have at least a part which is soluble in a solvent, for example water. In this case, the cascade with the captive inserts is exposed to water, for example by being immersed in a hot bath. The dissolution of the insert reduces its section and allows it to be separated from the walls of the cascade which were opposed to its removal.

[0127] The surface condition of the mould and of the inserts can make it possible to avoid a step of grinding of the contours of the cascade by numerically-controlled milling.

[0128] Obviously, the invention is not limited to the examples which have just been described.

[0129] In particular, the inserts of the mould can be produced in such a way that the removal from the mould is performed other than by the partial or total solubilization of the insert, for example by using fusible, brittle or flexible inserts, that can be removed by subjecting the cascade and the captive inserts to heating, impacts, vibrations, deformations.

[0130] The inserts can be entirely soluble, fusible, brittle or flexible, or, as a variant, comprise a core or other reusable part and an enclosure which is destroyed on each production cycle.