Rotationally symmetrical part made of composite material having an improved holding capacity

Abstract

The invention relates to a method for manufacturing a rotationally symmetrical part made of composite material (100) for a propulsion assembly comprising: - manufacturing a fibre preform on a mandrel (200) having a profile corresponding to that of the component to be manufactured, and - densifying the fibre preform using a matrix. The step of manufacturing the fibre preform comprises the formation of a fibre blank (140) in the form of a strip comprising at least one layer of continuous fibres and at least one layer of discontinuous fibres, the fibre blank being formed on the mandrel, the layer of continuous fibres of the fibre blank extending at least over a complete turn around the mandrel (200).

Description

[0001] Description

[0002] Title of the invention: Revolutionary part made of composite material with improved retention capacity

[0003] Technical Field

[0004] The present invention relates to the general field of the manufacture of composite material revolution parts for propulsion units such as gas turbine fan casings, air inlets or nacelle cowls for aeronautical engines.

[0005] Prior art

[0006] In an aeronautical gas turbine engine, the fan casing serves several functions. It defines the air inlet stream into the engine, supports an abradable material opposite the fan blade tips, supports a possible sound wave absorption structure for acoustic treatment at the engine inlet, and incorporates or supports a retention shield. The retention shield provides a debris trap that retains debris, such as ingested objects or fragments of damaged blades, projected by centrifugation, to prevent them from passing through the casing and reaching other parts of the aircraft.

[0007] Previously made of metallic material, the casings, like the fan casing, are now made of composite material, that is to say from a fibrous preform densified by an organic matrix, which makes it possible to produce parts with a lower overall mass than these same parts when they are made of metallic material while presenting a mechanical resistance at least equivalent if not superior.

[0008] The manufacture of a fan casing made of organic matrix composite material is described in particular in document US 8,322,971. In the casing disclosed in document US 8,322,971, the retention shield is constituted by a portion of excess thickness obtained at the level of the fibrous reinforcement of the casing which has an evolving thickness. The fibrous reinforcement is obtained by winding a 3D woven fibrous texture which has a portion of excess thickness capable of forming a retention shield.

[0009] However, in order to be able to contain debris projected with very high energy as in the case of the loss of a blade, the excess thickness portion must always have a significant dimension in the radial direction, which significantly increases the overall mass of the composite material part. The same is true for an air intake or a nacelle cowl of a propulsion unit.

[0010] Statement of the invention

[0011] It is therefore desirable to be able to have a solution for having a composite material revolution part for a propulsion unit having an overall mass lower than that of the composite material casings of the prior art while having a retention capacity that is at least equivalent if not superior.

[0012] To this end, according to the invention, a method is proposed for manufacturing a composite material revolution part for a propulsion unit comprising:

[0013] - the production of a fiber preform on a mandrel having a profile corresponding to that of the part to be manufactured, and

[0014] - densification of the fiber preform by a matrix, characterized in that the production of the fiber preform comprises the formation of a fiber blank in the form of a strip comprising at least one layer of continuous fibers and at least one layer of discontinuous fibers, the fiber blank being shaped on the mandrel, said at least one layer of continuous fibers of the fiber blank extending at least over one complete turn around the mandrel.

[0015] The method of the invention thus makes it possible to obtain a composite material part having an increased retention capacity thanks to the presence of one or more layers of discontinuous fibers in its fiber reinforcement. The layer(s) of discontinuous fibers are in fact capable of being damaged to dissipate energy in the event of impact with a projected object such as a blade in the case of an aeronautical engine casing (FBO for "Fan Blade Out"). The layer(s) of continuous fibers ensure the mechanical cohesion and strength of the part. It is thus possible to manufacture revolution parts made of composite material having a very good retention capacity without requiring an excessive increase in thickness, the parts having an overall mass lower than that of the composite material parts of the prior art.

[0016] According to one aspect of the method of the invention, the layer(s) of discontinuous fibers are a nonwoven texture with long discontinuous fibers or a mat of random fibers.

[0017] According to another aspect of the method of the invention, the layer(s) of continuous fibers are chosen from at least one of the following fiber structures: three-dimensional woven structure, stack of unidirectional plies, stack of two-dimensional woven plies, braid. The fiber blank may comprise a single layer of continuous fibers corresponding to a strip-shaped fiber structure having a three-dimensional weave between a plurality of warp threads and a plurality of weft threads. In this case, the production of the fiber preform comprises winding the fiber blank onto the mandrel over one or more turns.The fibrous blank may comprise a single layer of continuous fibers also corresponding to a strip-shaped fibrous structure having a three-dimensional weave which comprises in the lengthwise direction a first part in which the warp threads are bound by the weft threads over the entire thickness of the fibrous structure and a second part comprising a delinking zone present at an intermediate position in the thickness of the fibrous structure and extending in the fibrous structure along a plane parallel to the surface of the fibrous structure, the delinking zone separating the fibrous structure into first and second skins, the layer of discontinuous fibers being arranged between the first and second skins. In this case, the production of the fibrous structure comprises winding the fibrous blank onto the mandrel over one or more turns.

[0018] The invention also relates to a composite material revolution part for a propulsion unit comprising a fibrous reinforcement, said fibrous reinforcement being densified by a matrix, characterized in that the fibrous reinforcement comprises in the thickness direction at least one layer of continuous fibers and at least one layer of discontinuous fibers. As explained above, the composite material part of the invention offers a very good retention capacity while having a controlled thickness and, consequently, a reduced overall mass compared to that of the composite material parts of the prior art.

[0019] According to one aspect of the part of the invention, the one or more layers of discontinuous fibers are a nonwoven texture with long discontinuous fibers or a mat of random fibers.

[0020] According to another aspect of the part of the invention, the layer(s) of continuous fibers are chosen from at least one of the following fiber structures: three-dimensional woven structure, stack of unidirectional plies, stack of two-dimensional woven plies, braid. The fiber reinforcement may comprise a single layer of continuous fibers consisting of a strip-shaped fiber structure having a three-dimensional or multi-layer weave comprising a first portion in which warp threads are bound by weft threads over the entire thickness of the fiber structure and a second portion comprising a delinking zone present at an intermediate position in the thickness of the fiber structure, the delinking zone separating the fiber structure into first and second skins, the layer of discontinuous fibers being present between the first and second skins.

[0021] According to another aspect of the part of the invention, it corresponds to a casing comprising a ferrule comprising a portion of excess thickness forming a retention zone, the ferrule further comprising a flange at its axial ends.

[0022] Brief description of the drawings

[0023] [Fig. 1] Figure 1 is a perspective and partial sectional view of an aeronautical engine equipped with a fan casing made of composite material in accordance with one embodiment of the invention,

[0024] [Fig. 2] Figure 2 is a sectional view along plane II-II of the casing of Figure 1, [Fig. 3] Figure 3 is a schematic perspective view of a loom showing the weaving of a fibrous texture used for the formation of the fibrous reinforcement of the casing of Figures 1 and 2, [Fig. 4] Figure 4 is a schematic perspective view of a continuous fiber layer,

[0025] [Fig. 5] Figure 5 is a schematic perspective view of a discontinuous fiber layer,

[0026] [Fig. 6] Figure 6 is a schematic perspective view of a fiber blank formed with the layers of Figures 4 and 5 in accordance with one embodiment of the invention,

[0027] [Fig. 7] Figure 7 is a schematic perspective view showing the shaping of the fiber blank of Figure 6,

[0028] [Fig. 8] Figure 8 is a sectional view of a fiber preform obtained from the fiber blank of Figure 6,

[0029] [Fig. 9] Figure 9 is a schematic view showing a tool for densifying the preform of Figure 8,

[0030] [Fig. 10] Figure 10 is a schematic perspective view showing the formation of a fibrous blank in accordance with another embodiment of the invention,

[0031] [Fig. 11] Figure 11 is a sectional view of a casing made from the fiber blank of Figure 10.

[0032] Description of the embodiments

[0033] The invention applies generally to any rotating part made of composite material for a propulsion unit, the rotating part being likely to be exposed to impacts. Such parts for a propulsion unit relate in particular, but not exclusively, to gas turbine fan casings, nacelle air inlets and nacelle cowls present in aeronautical engines.

[0034] The invention will be described below in the context of its application to a fan casing of an aeronautical gas turbine engine.

[0035] Such an engine, as shown very schematically in Figure 1, comprises, from upstream to downstream in the direction of the gas flow, a fan 1 arranged at the engine inlet, a compressor 2, a combustion chamber 3, a high-pressure turbine 4 and a low-pressure turbine 5.

[0036] The engine is housed inside a casing comprising several parts corresponding to different elements of the engine. Thus, the fan 1 is surrounded by a fan casing 100.

[0037] Figure 2 shows a fan casing profile 100 made of composite material as it can be obtained by a method according to the invention. The internal surface 101 of the casing defines the air inlet stream. It can be provided with a layer of abradable coating 102 in line with the path of the fan blade tips, a blade 13 being partially shown very schematically. The abradable coating is therefore arranged over only part of the length (in the axial direction) of the casing. An acoustic treatment coating (not shown) can also be arranged on the internal surface 101, in particular upstream of the abradable coating 102.

[0038] The casing 100 may be provided with external flanges 104, 105 at its upstream and downstream ends in order to allow its mounting and connection with other elements.

[0039] The casing 100 is made of a composite material with fiber reinforcement densified by a matrix. The reinforcement is made of fibers, for example carbon, glass, aramid or ceramic, and the matrix is ​​made of polymer, for example epoxy, bismaleimide or polyimide, carbon or ceramic.

[0040] In the example described here, the fiber reinforcement is formed by winding a fiber blank onto a mandrel, the mandrel having a profile corresponding to that of the casing to be produced. Advantageously, the fiber reinforcement constitutes a complete tubular fiber preform of the casing 100 forming a single piece with reinforcement parts corresponding to the flanges 104, 105.

[0041] According to the invention, the fiber blank is made up of at least one layer of continuous fibers and at least one layer of discontinuous fibers assembled together as described below. In the example described here, the layer of continuous fibers is made up of a strip-shaped fiber structure having a three-dimensional weave. More precisely and as illustrated in FIG. 3, a fiber structure 50 is produced in a known manner by three-dimensional weaving using a jacquard-type loom 10 on which a bundle of warp threads or strands 20 has been arranged in a plurality of layers, the warp threads being linked by weft threads or strands 30. The threads used for weaving the fiber structure 50 are, for example, carbon fiber threads, for example HexTow® IM7, HexTow® AS4 or HexTow® AS7 fibers, or ceramic such as silicon carbide, glass, or aramid.The yarn count is typically 12k, 24k or 48k. Different types of yarns can be used within the same preform. The fiber structure is achieved by three-dimensional weaving. By "three-dimensional weaving" or "3D weaving" is meant here a weaving method by which at least some of the weft yarns bind warp yarns over several layers of warp yarns or vice versa. An example of three-dimensional weaving is the so-called "interlock" weave. By "interlock" we mean here a weaving weave in which each layer of warp yarns binds several layers of weft yarns with all the yarns of the same warp column having the same movement in the plane of the weave.

[0042] As illustrated in Figures 3 and 4, the fibrous structure 50 has a strip shape which extends lengthwise in a direction X corresponding to the direction of travel of the warp threads or strands 20 and widthwise or transversely in a direction Y corresponding to the direction of the weft threads or strands 30.

[0043] As illustrated in FIG. 4, the fibrous structure 50 has a strip shape having a thickness E 50 , for example 5 mm, corresponding to a 3D weave with between three and five layers of warp woven together in the plane and in the thickness of the strip using weft threads. The fibrous structure 50 extending over a width l 50 defined according to the width of the casing to be manufactured, the width l 50 which can be for example 2 m, and over a length L 50defined according to the diameter of the casing to be manufactured and the desired number of turns in the fiber reinforcement. For example, to manufacture a similar cylindrical casing with a diameter of 4 m by making 2 rough turns, the length of the fiber structure to be woven is approximately 25 m. The length can be extended to prevent the start and end of the fiber structure from being at the same angular position, which could create a weakness in the part. In the example described here, the layer of discontinuous fibers consists of a fiber mat. By "fiber mat" is meant a fibrous texture corresponding to an agglomerate of discontinuous fibers, the fibers being generally arranged randomly or in bulk so as to obtain isotropic behavior in the plane.In the invention, the production of the fiber mat can be adapted in order to obtain a mat with orthotropic properties allowing to have moduli in the plane as close as possible to the moduli in the warp direction and / or in the weft direction of the 3D woven fiber structure which can be different. In this case, the percentage of fibers in the direction of the sheet and the transverse direction can be influenced by the speed of advance of the conveyor system. The faster the advance, the more the fibers are statistically oriented in the direction of the roller. It is also possible to define drop wells which reorient the fibers more or less.

[0044] Figure 5 illustrates a strip-shaped fiber mat 60 comprising fibers 61 randomly distributed over a thickness E6o preferably between 1 mm and 5 mm. In the example described here, the fiber mat 60 has a width l6o equivalent to the width l 50of the fibrous structure 50 and a length L6o less than the length L 50 of the fibrous structure 50 so that only the fibrous structure 50 is present in the last winding turn of the fibrous blank. The fiber mat 60 preferably comprises the same type of fibers as the fibrous structure 50. The weight of the fiber mat is typically between 200 g / m 2 and 1000 g / m 2 even if higher weights can be used.

[0045] A fiber blank 140 is then produced by placing the fiber mat 60 on the 3D woven fiber structure 50 as illustrated in FIG. 6. A step of sewing the assembly edges between the fiber mat 60 and the fiber structure 50 can also be carried out in order to hold them in position in the fiber blank 140. The fiber blank 140 can be compacted in order to reduce the swelling before it is wound.

[0046] As illustrated in Figure 7, a fiber preform is then formed by winding in a direction S R on a mandrel 200 of the fiber blank 140 with the fiber structure 50 arranged against the mandrel 200, the mandrel having a profile corresponding to that of the casing to be produced. The mandrel 200 has an external surface 201 whose profile corresponds to the internal surface of the casing to be produced. By its winding on the mandrel 200, the fiber blank 140 matches the profile thereof. The mandrel 200 also comprises two flanges 220 and 230 to form fiber preform parts corresponding to the flanges 104 and 105 of the casing 100.

[0047] Figure 8 shows a sectional view of the fiber preform 300 obtained after winding the fiber blank 140 in several layers on the mandrel 200. The number of turns or coils depends on the desired thickness and the thickness of the fiber texture. It is preferably at least equal to 2. In the example described here, the preform 300 comprises, along the direction of its thickness, two layers 51 and 52 of fiber structure 50 and two layers 62 and 63 of fiber mat 60, the layer 62 being interposed between the adjacent layers 51 and 52 while the layer 63 is present on the external periphery of the preform 300. The fiber preform 300 also comprises end portions 320, 330 corresponding to the flanges 104, 105 of the casing.

[0048] The fiber preform 300 is then densified using a matrix.

[0049] The densification of the fibrous preform consists of filling the porosity of the preform, in all or part of its volume, with the material constituting the matrix.

[0050] The matrix can be obtained in a manner known per se using the liquid method.

[0051] The liquid method consists of impregnating the preform with a liquid composition containing an organic precursor of the matrix material. The organic precursor is usually in the form of a polymer, such as a resin, possibly diluted in a solvent. The fibrous preform is placed in a mold that can be closed in a sealed manner with a housing having the shape of the final molded part. As illustrated in Figure 9, the fibrous preform 300 is here placed between a plurality of sectors 240 forming a counter-mold and the mandrel 200 forming a support, these elements having respectively the external shape and the internal shape of the casing to be produced. Then, the liquid matrix precursor, for example a resin, is injected into the entire housing to impregnate the entire fibrous part of the preform.The transformation of the precursor into an organic matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after removal of any solvent and crosslinking of the polymer, the preform being always maintained in the mold having a shape corresponding to that of the part to be produced. The organic matrix can be obtained in particular from epoxy resins, such as, for example, the high-performance epoxy resin sold, or from liquid precursors of carbon or ceramic matrices.

[0052] In the case of carbon or ceramic matrix formation, the heat treatment consists of pyrolyzing the organic precursor to transform the organic matrix into a carbon or ceramic matrix depending on the precursor used and the pyrolysis conditions. For example, liquid carbon precursors can be resins with a relatively high coke content, such as phenolic resins, while liquid ceramic precursors, particularly SiC, can be polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) resins. Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification.

[0053] According to one aspect of the invention, the densification of the fiber preform can be carried out by the well-known transfer molding process known as RTM ("Resin Transfer Molding"). According to the RTM process, the fiber preform is placed in a mold having the shape of the casing to be produced. A thermosetting resin is injected into the internal space delimited between the mandrel 200 and the counter-molds 240.

[0054] The resin used can be, for example, an epoxy resin. Resins suitable for RTM processes are well known. They preferably have a low viscosity to facilitate their injection into the fibers. The choice of temperature class and / or the chemical nature of the resin is determined according to the thermomechanical stresses to which the part must be subjected. Once the resin has been injected throughout the reinforcement, it is polymerized by heat treatment in accordance with the RTM process.

[0055] After injection and polymerization, the part is demolded. Finally, the part is trimmed to remove excess resin and the chamfers are machined to obtain the casing 100 illustrated in Figures 1 and 2. The casing 100 made of composite material thus comprises a fiber reinforcement consisting in the direction of its thickness of two layers 51 and 52 of fiber structure 50 and two layers 62 and 63 of fiber mat 60, the layer 62 being interposed between the adjacent layers 51 and 52 while the layer 63 is present on the external periphery of the casing 100. The number of turns or coils of continuous fiber layers (here the fiber structure 50) is a function of the desired thickness and the thickness of the layer. It is preferably at least equal to 2. The number of turns or coils of layers of discontinuous fibers (here the fiber mat 60) depends on the desired retention capacity.The casing 100 thus has over its entire width a retention zone or shield capable of retaining debris, particles or objects ingested at the engine inlet, or originating from damage to fan blades, and projected radially by rotation of the fan, to prevent them from passing through the casing and damaging other parts of the aircraft. The layer of discontinuous fibers constituted here by the fiber mat 60 may have a width less than that of the layer of continuous fibers constituted here by the fiber structure 50. In this case, the layer of discontinuous fibers forms an excess thickness in the casing as described below corresponding to the retention zone or shield of the casing.

[0056] Figure 10 illustrates the formation of a fiber blank 440 according to another embodiment of the invention. The fiber blank 440 is formed by assembling a layer of continuous fibers with a layer of discontinuous fibers. More precisely and as illustrated in Figure 10, a fiber structure 70 is produced in a known manner by 3D weaving with, for example, carbon fiber yarns, for example HexTow® IM7, HexTow® AS4 or HexTow® AS7 fibers, or ceramic such as silicon carbide, glass, or even aramid. The yarn count is typically 12k, 24k or 48k. Different types of yarns can be used within the same preform.

[0057] As illustrated in Figure 10, the fibrous structure 70 has a strip shape which extends lengthwise in a direction X corresponding to the direction of travel of the warp threads or strands and widthwise or transversely in a direction Y corresponding to the direction of the weft threads or strands. The fibrous structure 70 has a strip shape having a thickness E7o, for example 10 mm corresponding to a 3D weave with between six and ten layers of warp woven together in the plane and in the thickness of the strip using weft threads. The fibrous structure 70 extending over a width l 70 defined according to the width of the casing to be manufactured, the width l 70 which can be for example 2 m, and over a length L 70defined according to the diameter of the casing to be manufactured and the desired number of turns in the fiber reinforcement. For example, to manufacture a similar cylindrical casing of 4 m in diameter by making 2 turns of the preform, the length of the fiber structure to be woven is approximately 25 m. The length can be extended to prevent the start and end of the fiber structure from being at the same angular position, which could create a weakness in the part.

[0058] The fiber blank 440 further comprises a layer of staple fibers. In the example described herein, the layer of staple fibers is constituted by a nonwoven texture with long staple fibers 80 (DLF). The long staple fibers have a length of between 8 mm and 100 mm, for example 12.5, 25 or 50 mm.

[0059] In the example described here, the nonwoven texture with long discontinuous fibers 80 has smaller dimensions than the fibrous structure 70 so as to form a portion of excess thickness in the final casing as described below. Thus, the texture 80 has a strip shape having a width l 80 less than the width l 70 of the fibrous structure 70 and a length L8o corresponding to less than or equal to half the length L 70 of the fibrous structure 70 so that only the fibrous structure 70 is present in the first or last winding turn of the fibrous blank depending on the winding arrangement of the blank on the mandrel. The texture 80 has a thickness E 80preferably between 1 mm and 5 mm. The texture 80 preferably comprises the same type of fibers as the fibrous structure 70. The fibrous texture 80 is preferably compacted before its insertion into the structure 70. The fibrous structure 70 may also be compacted in order to facilitate the insertion of the texture 80.

[0060] The fibrous blank 440 further differs from the fibrous blank 140 described previously in that the nonwoven texture with long discontinuous fibers 80 is inserted into a debonded portion of the fibrous structure 70. More specifically, the fibrous structure 70 comprises a first part 75 comprising an internal debonding zone 71 and a second part 76 without debonding. The first part 75 may for example have a length of 12 m while the second part may have a length of 13 m. In this case, the nonwoven texture with long discontinuous fibers 80 has a length less than or equal to 12 m. The debonding zone 71 locally forms in the fibrous structure 70 first and second superimposed skins 73 and 74 and separated from each other along a plane parallel to the surface of the fibrous structure 70 so as to delimit between them an internal housing 72.In a known manner, the debonding zone 71 is obtained by defining a plane parallel to the surface of the fibrous structure 70 and typically located at half the thickness E. 70 of the structure 70 which is not crossed by weft threads. More precisely, in the example described here, the weft threads present in the first skin 73 do not extend into the layers of warp threads of the second skin 74 while the weft threads present in the second skin 74 do not extend into the layers of warp threads of the first skin 73 in order to form the unlinking zone 71. The skins 73 and 74 each comprise, for example, three to five layers of warp woven together in the plane and in the thickness of the strip using weft threads. The skins can of course comprise a different number of layers of warp.

[0061] Still in the example described here, the delinking zone does not extend to the lateral edges of the fibrous structure, thus forming a “sock”-shaped housing. The delinking zone may, however, extend to the lateral edges of the fibrous structure, thus separating the fibrous structure into two skins across its entire width.

[0062] The fibrous blank 440 is formed by inserting the long staple fiber nonwoven texture 80 into the housing 72 of the fibrous structure 70 as illustrated in FIG. 10.

[0063] A fiber preform is then formed by winding the fiber blank 440 onto a mandrel as for the fiber blank 140 of FIG. 7.

[0064] The winding onto the mandrel may begin with the first portion 75 or the second portion 76 of the fibrous structure 70 depending on the stacking order that is desired in the thickness direction (namely first skin 73, texture 80, second skin 74 and second portion 76 or second portion 76, first skin 73, texture 80 and second skin 74). In the example described here, it is the first portion 75 of the fibrous structure 70 that is wound first onto the mandrel.

[0065] The fiber preform is then densified using a matrix according to the conditions already described previously for the fiber preform 300.

[0066] After injection and polymerization, the part is demolded. Finally, the part is trimmed to remove excess resin and the chamfers are machined to obtain a casing 600 illustrated in Figure 1 1. The internal surface 601 of the casing defines the air inlet duct. It may be provided with a layer of abradable coating and / or an acoustic treatment coating (not shown in Figure 1 1). The casing 600 here has external flanges 604, 605 at its upstream and downstream ends to allow its assembly and connection with other elements.

[0067] The casing 600 made of composite material thus comprises a fibrous reinforcement consisting, between its internal periphery and its external periphery, of the first skin 73 of the first part 75 of the fibrous structure 70, of the non-woven texture with long discontinuous fibers 80, of the second skin 74 of the first part 75 of the fibrous structure 70 and of the second part 76 of the fibrous structure 70. The number of turns or coils of layers of continuous fibers (here the fibrous structure 70) is a function of the desired thickness and the thickness of the layer. It is preferably at least equal to 2. The number of turns or coils of layers of discontinuous fibers (here the non-woven texture with long discontinuous fibers 80) is a function of the desired retention capacity.

[0068] In the example described here, the casing 600 further comprises a portion of extra thickness 610 formed by the insertion of the nonwoven texture with long discontinuous fibers 80 into the fibrous structure 70. This portion of extra thickness forms a retention zone or shield capable of retaining debris, particles or objects ingested at the engine inlet, or originating from damage to fan blades, and projected radially by rotation of the fan, to prevent them from passing through the casing and damaging other parts of the aircraft. The presence of a layer of discontinuous fibers over the entire width of the part (casing 100) or over a portion of the width of the part (casing 600) makes it possible to give the part a very good retention capacity.

[0069] In the examples described above, the layer of continuous fibers is a strip having a 3D weave. The layer of continuous fibers can also be a stack of unidirectional plies, a stack of two-dimensional woven plies, or even a braid.

[0070] The layer of discontinuous fibers may in particular be a non-woven texture with long discontinuous fibers or a mat of random fibers. The manufacturing method described above in relation to a fan casing of an aeronautical gas turbine engine also applies to the manufacturing of other revolution parts made of composite material for propulsion systems such as nacelle air intakes or nacelle cowls.

Claims

Demands

1. Method for manufacturing a part of revolution made of composite material (100) for a propulsion assembly comprising: - the production of a fibrous preform (300) on a mandrel (200) having a profile corresponding to that of the part to be manufactured, and - the densification of the fibrous preform (300) by a matrix, characterized in that the realization of the fibrous preform includes the formation of a fibrous blank (140) in the form of a strip comprising at least one layer of continuous fibers and at least one layer of discontinuous fibers, the fibrous blank being shaped on the mandrel, said at least one layer of continuous fibers of the fibrous blank extending at least over one complete turn around the mandrel (200).

2. Method according to claim 1, wherein said at least one layer of discontinuous fibers is a discontinuous long fiber nonwoven texture (80) or a random fiber mat (60).

3. A method according to claim 1 or 2, wherein said at least one continuous fibre layer is selected from at least one of the following fibrous structures: three-dimensional woven structure, stacking of unidirectional layers, stacking of two-dimensional woven layers, braid.

4. A method according to claim 3, wherein the fibrous blank (140) comprises a layer of continuous fibers corresponding to a strip-shaped fibrous structure (50) having a three-dimensional weave between a plurality of warp yarns (20) and a plurality of weft yarns (30) and wherein the realization of the fibrous preform comprises winding the fibrous blank onto the mandrel in one or more turns.

5. A method according to claim 3, wherein the fibrous blank comprises a layer of continuous fibers corresponding to a strip-shaped fibrous structure (70) having a weave three-dimensional comprising in the length direction a first part (76) in which the warp yarns are linked by the weft yarns over the entire thickness of the fibrous structure and a second part (75) comprising a debinding zone (71) present at an intermediate position in the thickness of the fibrous structure and extending in the fibrous structure along a plane parallel to the surface of the fibrous structure, the debinding zone (71) separating the fibrous structure into first and second skins (73, 74), a layer of discontinuous fibers being disposed between the first and second skins, and in which the realization of the fibrous structure comprises winding the fibrous blank onto the mandrel in one or more turns.

6. Composite material part of revolution (100) for propulsion assembly comprising a fibrous reinforcement, said fibrous reinforcement being densified by a matrix, characterized in that the fibrous reinforcement comprises in the thickness direction at least one layer of continuous fibers and at least one layer of discontinuous fibers.

7. Part according to claim 6, wherein said at least one layer of discontinuous fibers is a discontinuous long fiber nonwoven texture (80) or a random fiber mat (60).

8. Part according to claim 6 or 7, wherein said at least one continuous fibre layer is selected from at least one of the following fibrous structures: three-dimensional woven structure, stacking of unidirectional layers, stacking of two-dimensional woven layers, braid.

9. A part according to claim 8, wherein the fibrous reinforcement comprises a layer of continuous fibers corresponding to a strip-shaped fibrous structure (70) having a three-dimensional or multilayer weave comprising a first portion (76) in which warp yarns are bonded by weft yarns over the entire thickness of the fibrous structure and a second portion (75) comprising a debonding zone (71) present at an intermediate position in the thickness of the fibrous structure, the unbinding zone (71) separating the fibrous structure into first and second skins (73, 74), the layer of discontinuous fibers being present between the first and second skins.

10. Part according to any one of claims 6 to 9, the part corresponding to a housing (600) comprising a ferrule having a portion of excess thickness (610) forming a retention zone, the ferrule further comprising at its axial ends a flange (604, 605).

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