Revolution part made of composite material with improved retention capacity

Abstract

A process for manufacturing a part of revolution made of composite material with improved retention capacity. A process for manufacturing a part of revolution made of composite material (100) comprises: - the production of a fibrous preform on a mandrel (200) having a profile corresponding to that of the part to be manufactured, and - the densification of the fibrous preform by a matrix. The production 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, the continuous fiber layer of the fibrous blank extending at least one full revolution around the mandrel (200). Figure for the abstract: Fig. 7.

Description

Title of the invention: Composite material part of revolution with improved retention capacity technical field

[0001] The present invention relates to the general field of manufacturing parts of revolution exposed to impacts and more particularly, but not exclusively, to gas turbine blower housings for aeronautical engines. Previous technique

[0002] In a gas turbine aircraft engine, the fan casing performs several functions. It defines the air intake duct into the engine, supports an abradable material opposite the fan blade tips, supports an optional sound-wave absorption structure for acoustic treatment at the engine inlet, and incorporates or supports a retention shield. The retention shield acts as a debris trap, retaining debris, such as ingested objects or fragments of damaged blades, ejected by centrifugal force, to prevent them from passing through the casing and reaching other parts of the aircraft.

[0003] Previously made of metallic material, housings, such as the blower housing, 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 the same parts when made of metallic material while having at least equivalent or even greater mechanical resistance.

[0004] The manufacture of a blower housing made of an organic matrix composite material is described in particular in US patent 8,322,971. In the housing disclosed in US patent 8,322,971, the retention shield is formed by an excess thickness obtained in the housing's fibrous reinforcement, which has a progressively increasing thickness. The fibrous reinforcement is obtained by winding a 3D woven fibrous texture that has an excess thickness suitable for forming a retention shield.

[0005] 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 portion of excess thickness must always have a significant dimension in the radial direction, which significantly increases the overall mass of the part made of composite material. Description of the invention

[0006] It is therefore desirable to have a solution for obtaining a part of revolution made of composite material having an overall mass lower than that of the prior art composite housings while having a capacity of retention at least equivalent if not superior.

[0007] To this end, according to the invention, a method for manufacturing a part of revolution made of composite material is proposed, comprising: - the production of a fibrous preform on a mandrel having a profile corresponding to that of the part to be manufactured, and - the densification of the fibrous preform by a matrix, characterized in that the realization of the fibrous preform includes the formation of a fibrous blank 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.

[0008] The process of the invention thus makes it possible to obtain a composite material part with increased retention capacity thanks to the presence of one or more layers of discontinuous fibers in its fibrous reinforcement. The discontinuous fiber layer(s) are indeed capable of being damaged in order to dissipate energy in the event of an impact with a projected object such as a fan blade in the case of an aircraft engine casing (FBO for "Fan Blade Out"). The continuous fiber layer(s) ensure the cohesion and mechanical strength of the part.

[0009] It is thus possible to manufacture parts of revolution in 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 parts in composite material of the prior art.

[0010] According to one aspect of the process of the invention, the discontinuous fiber layer(s) are a discontinuous long fiber nonwoven texture or a random fiber mat.

[0011] According to another aspect of the process of the invention, the continuous fiber layer(s) are 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. The fiber blank may comprise a single layer of continuous fibers corresponding to a strip-shaped fibrous structure exhibiting a three-dimensional weave between a plurality of warp yarns and a plurality of weft yarns. In this case, the fabrication of the fiber preform comprises winding the fiber blank onto the mandrel in one or more turns.The fibrous blank may comprise a single layer of continuous fibers also corresponding to a band-shaped fibrous structure having a three-dimensional weave which has in the length direction a first part in which the warp yarns are linked by the weft yarns over the entire thickness of the fibrous structure and a second part comprising a debinding zone present at an intermediate position in the thickness of the fibrous structure and extending into the . The fibrous structure follows a plane parallel to its surface, with the debonding zone separating it into first and second layers. The layer of discontinuous fibers is positioned between the first and second layers. In this case, the fabrication of the fibrous structure involves winding the fiber blank onto the mandrel in one or more turns.

[0012] The invention also relates to a part of revolution made of composite material 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.

[0013] As explained above, the composite material part of the invention offers very good retention capacity while having a controlled thickness and, consequently, a reduced overall mass compared to that of composite material parts of the prior art.

[0014] According to one aspect of the part of the invention, the discontinuous fiber layer(s) are a discontinuous long fiber nonwoven texture or a random fiber mat.

[0015] According to another aspect of the invention, the continuous fiber layer(s) are 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. The fibrous reinforcement may comprise a single layer of continuous fibers consisting of a strip-shaped fibrous structure having a three-dimensional or multi-layered weave comprising a first part in which warp yarns are bonded by weft yarns throughout the thickness of the fibrous structure and a second part comprising a debonding zone located at an intermediate position within the thickness of the fibrous structure, the debonding zone separating the fibrous structure into first and second skins, the discontinuous fiber layer being located between the first and second skins.

[0016] According to another aspect of the part of the invention, it corresponds to a housing comprising a ferrule having a portion of overthickness forming a retention zone, the ferrule further comprising at its axial ends a flange. Brief description of the drawings

[0017] [Fig-1] [Fig. 1] is a perspective and partial cross-sectional view of an aero engine nautical vessel equipped with a blower housing made of composite material according to an embodiment of the invention,

[0018] [Fig.2] The [Fig.2] is a cross-sectional view along plane II-II of the housing of the [Fig.1],

[0019] [Fig.3] Fig.3 is a schematic perspective view of a loom showing the weaving of a fibrous texture used for forming the fibrous reinforcement of the casing in Figures 1 and 2,

[0020] [Fig.4] Fig.4 is a schematic perspective view of a continuous fiber layer,

[0021] [Fig.5] Fig.5 is a schematic perspective view of a discontinuous fiber layer,

[0022] [Fig.6] Fig.6 is a schematic perspective view of a fibrous blank formed with the layers of Figures 4 and 5 according to one embodiment of the invention,

[0023] [Fig.7] The [Fig.7] is a schematic perspective view showing the shaping of the fibrous blank of the [Fig.6],

[0024] [Fig.8] The [Fig.8] is a cross-sectional view of a fibrous preform obtained from the fibrous blank of the [Fig.6],

[0025] [Fig.9] The [Fig.9] is a schematic view showing a densification tooling for the preform of the [Fig.8],

[0026] [Fig. 10] The [Fig. 10] is a schematic perspective view showing the formation of a fibrous blank according to another embodiment of the invention,

[0027] [Fig. 11] The [Fig. 11] is a cross-sectional view of a housing made from the fibrous blank of the [Fig. 10]. Description of the implementation methods

[0028] The invention applies generally to any part of revolution made of composite material exposed to impacts.

[0029] The invention will be described below in the context of its application to a blower housing for an aeronautical gas turbine engine.

[0030] Such an engine, as shown very schematically by [Fig.1], comprises, from upstream to downstream in the direction of the gas flow, a blower 1 disposed at the inlet of the engine, a compressor 2, a combustion chamber 3, a high-pressure turbine 4 and a low-pressure turbine 5.

[0031] The motor is housed inside a casing comprising several parts corresponding to different elements of the motor. Thus, the blower 1 is surrounded by a blower casing 100.

[0032] Figure 2 shows a profile of a fan casing 100 made of composite material as obtained by a process according to the invention. The internal surface 101 of the casing defines the air inlet duct. It can be provided with an abradable coating layer 102 along the path of the fan blade tips, one blade 13 being partially shown schematically. The abradable coating is therefore disposed over only a portion of the length (in the axial direction) of the casing. An acoustic treatment coating (not shown) can also be disposed on the internal surface 101, particularly upstream of the abradable coating 102.

[0033] The housing 100 can be provided with external flanges 104, 105 at its upstream and downstream ends in order to allow its assembly and connection with other elements.

[0034] The housing 100 is made of a fiber-reinforced composite material densified by a matrix. The reinforcement is made of fibers, for example, carbon, glass, aramid or ceramic, and the matrix is ​​made of a polymer, for example, epoxy, bismaleimide or polyimide, carbon or ceramic.

[0035] 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 housing to be produced. Advantageously, the fiber reinforcement constitutes a complete tubular fiber preform of the housing 100, forming a single piece with reinforcement portions corresponding to the flanges 104, 105.

[0036] According to the invention, the fibrous blank consists 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 consists of a strip-shaped fibrous structure having a three-dimensional weave. More specifically, and as illustrated in [Fig. 3], a fibrous structure 50 is produced in a known manner by three-dimensional weaving using a Jacquard-type loom 10 on which a bundle of warp yarns or strands 20 is arranged in a plurality of layers, the warp yarns being linked by weft yarns or strands 30. The yarns used for weaving the fibrous structure 50 are, for example, carbon fiber yarns, such as HexTow® IM7, HexTow® AS4, or HexTow® AS7 fibers, or ceramic yarns such as silicon carbide, glass, or aramid.The yarn count is typically 12k, 24k, or 48k. Different yarn types can be used within the same preform. The fibrous structure is achieved through three-dimensional weaving. "Three-dimensional weaving" or "3D weaving" refers to a weaving method in which at least some of the weft yarns interlock with warp yarns across multiple layers of warp yarns, or vice versa. An example of three-dimensional weaving is the interlock weave. Interlock weaving refers to a weave structure in which each layer of warp yarns interlocks with multiple layers of weft yarns, with all yarns in the same warp column having the same movement within the plane of the weave.

[0037] As illustrated in figures 3 and 4, the fibrous structure 50 has a band shape which extends lengthwise in a direction X corresponding to the direction of the warp yarns or strands 20 and widthwise or transversely in a direction Y corresponding to the direction of the weft yarns or strands 30.

[0038] As illustrated in [Fig. 4], the fibrous structure 50 has a band shape having a thickness E50, for example 5 mm, corresponding to a 3D weave with between three and five warp layers woven together in the plane and in the thickness The fiber structure 50 is woven from the strip using weft threads. The fiber structure extends over a width l50, defined according to the width of the housing to be manufactured (for example, l50 could be 2 m), and over a length L50, defined according to the diameter of the housing and the desired number of turns in the fiber reinforcement. For example, to manufacture a cylindrical housing with a diameter of 4 m using 2 rough turns, the length of the fiber structure to be woven is approximately 25 m. This length can be increased to prevent the beginning and end of the fiber structure from being at the same angular position, which could create a weakness in the part.

[0039] In the example described here, the layer of discontinuous fibers consists of a fiber mat. By "fiber mat," we mean a fibrous texture corresponding to an agglomeration of discontinuous fibers, the fibers generally being arranged randomly or loosely so as to obtain isotropic behavior in the plane. In the invention, the implementation of the fiber mat can be adapted to obtain a mat with orthotropic properties allowing for in-plane moduli that closely approximate the warp and / or weft moduli of the 3D woven fibrous structure, which may differ. In this case, the percentage of fibers in the web direction and the transverse direction can be influenced by the feed speed of the conveying system. The faster the feed speed, the more the fibers are statistically oriented in the direction of the roller. It is also possible to define drop holes that reorient the fibers to a greater or lesser extent.

[0040] Figure 5 illustrates a strip-shaped fiber mat 60 comprising fibers 61 randomly distributed over a thickness E60 preferably between 1 mm and 5 mm. In the example described here, the fiber mat 60 has a width l60 equivalent to the width l50 of the fiber structure 50 and a length L60 less than the length L50 of the fiber structure 50, so that only the fiber structure 50 is present in the last winding of the fiber blank. The fiber mat 60 preferably comprises the same type of fibers as the fiber structure 50. The basis weight of the fiber mat is typically between 200 g / m² and 1000 g / m², although higher basis weights can be used.

[0041] 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 stitching step of the joining edges between the fiber mat 60 and the fiber structure 50 can also be performed to hold them in position within the fiber blank 140. The fiber blank 140 can be compacted to reduce bulk before winding.

[0042] As illustrated in [Fig. 7], a fibrous preform is then formed by winding the fibrous blank 140 in a direction SR onto a mandrel 200 with the A fibrous structure 50 is positioned against the mandrel 200, the mandrel having a profile corresponding to that of the housing to be produced. The mandrel 200 has an external surface 201 whose profile corresponds to the internal surface of the housing to be produced. By winding around the mandrel 200, the fibrous blank 140 conforms to its profile. The mandrel 200 also includes two flanges 220 and 230 to form portions of the fibrous preform corresponding to the flanges 104 and 105 of the housing 100.

[0043] Figure 8 shows a cross-sectional view of the fibrous preform 300 obtained after winding the fibrous blank 140 in several layers onto the mandrel 200. The number of turns or spirals depends on the desired thickness and the thickness of the fibrous texture. It is preferably at least 2. In the example described here, the preform 300 comprises, along its thickness, two layers 51 and 52 of fibrous structure 50 and two layers 62 and 63 of fiber mat 60, layer 62 being interposed between the adjacent layers 51 and 52, while layer 63 is present on the outer periphery of the preform 300. The fibrous preform 300 also includes end portions 320, 330 corresponding to the flanges 104, 105 of the housing.

[0044] The fibrous preform 300 is then densified by a matrix.

[0045] The densification of the fibrous preform consists of filling the porosity of the preforms, in all or part of its volume, by the material constituting the matrix.

[0046] The matrix can be obtained in a manner known per se following the liquid-based process.

[0047] The liquid process 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 sealed tightly with a cavity having the shape of the final molded part. As illustrated in [Fig. 9], the fibrous preform 300 is placed between a plurality of sectors 240 forming a counter-mold and the mandrel 200 forming a support, these elements having respectively the external and internal shapes of the housing to be produced. Then, the liquid matrix precursor, for example a resin, is injected throughout the cavity to impregnate the entire fibrous portion of the preform.

[0048] 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 always being held in the mold having a shape corresponding to that of the part to be produced. The organic matrix can notably be obtained from epoxy resins, such as such as, for example, high-performance epoxy resin sold, or liquid precursors of carbon or ceramic matrices.

[0049] In the case of forming a carbon or ceramic matrix, 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), polytitanocarbosilane (PTCS), or polysilazane (PSZ) type resins. Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification.

[0050] According to one aspect of the invention, the densification of the fibrous preform can be achieved by the well-known resin transfer molding (RTM) process. According to the RTM process, the fibrous preform is placed in a mold having the shape of the housing to be produced. A thermosetting resin is injected into the internal space defined between the mandrel 200 and the counter-molds 240.

[0051] 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.

[0052] 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 housing 100 illustrated in Figures 1 and 2. The composite housing 100 thus comprises a fibrous reinforcement consisting, along its thickness, of two layers 51 and 52 of fibrous structure 50 and two layers 62 and 63 of fiber mat 60, layer 62 being interposed between the adjacent layers 51 and 52, while layer 63 is present on the outer periphery of the housing 100. The number of turns or spirals of continuous fiber layers (here, the fibrous structure 50) depends on the desired thickness and the thickness of the layer. It is preferably at least equal to 2. The number of turns or spirals of discontinuous fiber layers (here the 60 fiber mat) depends on the desired retention capacity.The crankcase 100 thus features, across its entire width, a retention zone or shield capable of trapping debris, particles, or objects ingested at the engine inlet, or originating from damage to the fan blades, and projected radially by the fan's rotation, to prevent them from passing through the crankcase and damaging other parts of the aircraft. The fiber layer. discontinuous fiber mat 60 can have a width less than that of the continuous fiber layer constituted here by the fibrous structure 50. In this case, the discontinuous fiber layer forms an overthickness in the housing as described below corresponding to the retention zone or shield of the housing.

[0053] Figure 10 illustrates the formation of a fibrous blank 440 according to another embodiment of the invention. The fibrous blank 440 is formed by combining a layer of continuous fibers with a layer of discontinuous fibers. More specifically, and as illustrated in Figure 10, a fibrous structure 70 is produced in a known manner by 3D weaving with, for example, carbon fiber yarns, such as HexTow® IM7, HexTow® AS4, or HexTow® AS7 fibers, or ceramics 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.

[0054] As illustrated in [Fig. 10], the fibrous structure 70 has a strip-like shape extending lengthwise in a direction X corresponding to the direction of the warp yarns or strands and widthwise or transversely in a direction Y corresponding to the direction of the weft yarns or strands. The fibrous structure 70 has a strip-like shape with a thickness E70, for example 10 mm, corresponding to a 3D weave with between six and ten warp layers woven together in the plane and in the thickness of the strip using weft yarns. The fibrous structure 70 extends over a width l70 defined according to the width of the housing to be manufactured, the width l70 being, for example, 2 m, and over a length L70 defined according to the diameter of the housing to be manufactured and the desired number of turns in the fibrous reinforcement.For example, to manufacture a cylindrical housing with a diameter of 4 m by making 2 turns of the preform, the length of the fibrous structure to be woven is approximately 25 m. The length can be increased to prevent the beginning and end of the fibrous structure from being in the same angular position, which could create a weakness in the part.

[0055] The fibrous blank 440 further comprises a layer of discontinuous fibers. In the example described here, the discontinuous fiber layer consists of a long discontinuous fiber nonwoven texture 80 (DLF). The long discontinuous fibers have a length between 8 mm and 100 mm, for example 12.5, 25, or 50 mm.

[0056] In the example described here, the discontinuous long-fiber nonwoven texture 80 has smaller dimensions than the fibrous structure 70 so as to form a portion of extra thickness in the final casing as described below. Thus, the texture 80 has a strip shape having a width l80 less than the width l70 of the fibrous structure 70 and a corresponding length L80 less than or equal to half The length L70 of the fibrous structure 70 is such that only the fibrous structure 70 is present in the first or last winding of the fibrous blank, depending on the winding arrangement of the blank on the mandrel. The texture 80 has a thickness E80 preferably 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 being inserted into the structure 70. The fibrous structure 70 may also be compacted to facilitate the insertion of the texture 80.

[0057] 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 having 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 within the fibrous structure 70 first and second overlapping skins 73 and 74, separated from each other along a plane parallel to the surface of the fibrous structure 70 so as to delimit an internal compartment 72 between them.As is known, the unbinding zone 71 is obtained by defining a plane parallel to the surface of the fibrous structure 70 and typically located at half the thickness E70 of the structure 70, which is not traversed by weft yarns. More precisely, in the example described here, the weft yarns in the first skin 73 do not extend into the warp yarn layers of the second skin 74, while the weft yarns in the second skin 74 do not extend into the warp yarn layers of the first skin 73, in order to form the unbinding zone 71. Skins 73 and 74 each have, for example, three to five warp layers woven together in the plane and in the thickness of the web using weft yarns. The skins can, of course, have a different number of warp layers.

[0058] Still in the example described here, the debonding zone does not extend to the lateral edges of the fibrous structure, thus forming a "sock-shaped" housing. However, the debonding zone can extend to the lateral edges of the fibrous structure, thus separating the fibrous structure into two layers across its entire width.

[0059] The fibrous blank 440 is formed by inserting the discontinuous long-fiber non-woven texture 80 into the housing 72 of the fibrous structure 70 as illustrated in [Fig. 10].

[0060] A fibrous preform is then formed by winding the blank onto a mandrel fibrous 440 as for the fibrous rough 140 of [Fig.7].

[0061] Winding onto the mandrel can begin with the first part 75 or the second part 76 of the fibrous structure 70 depending on the desired stacking order in the thickness direction (namely first skin 73, texture 80, second skin 74 and second part 76 or second part 76, first skin 73, texture 80 and second skin 74). In the example described here, it is the first part 75 of the fibrous structure 70 that is wound onto the mandrel first.

[0062] The densification of the fibrous preform is then carried out by a matrix according to the conditions already described previously for the fibrous preform 300.

[0063] 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 housing 600 illustrated in [Fig. 11]. The internal surface 601 of the housing defines the air inlet channel. It can be provided with an abradable coating and / or an acoustic treatment coating (not shown in [Fig. 11]). The housing 600 is here fitted with external flanges 604, 605 at its upstream and downstream ends to allow for its assembly and connection with other components.

[0064] The composite material housing 600 thus comprises a fibrous reinforcement consisting, between its inner and outer peripheries, of the first skin 73 of the first part 75 of the fibrous structure 70, the non-woven texture with long discontinuous fibers 80, the second skin 74 of the first part 75 of the fibrous structure 70, and the second part 76 of the fibrous structure 70. The number of turns or spirals of continuous fiber layers (here, the fibrous structure 70) depends on the desired thickness and the thickness of the layer. It is preferably at least 2. The number of turns or spirals of discontinuous fiber layers (here, the non-woven texture with long discontinuous fibers 80) depends on the desired retention capacity.

[0065] In the example described here, the casing 600 further comprises a portion of extra thickness 610 formed by the insertion of the non-woven 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.

[0066] The presence of a layer of discontinuous fibers over the entire width of the part (case 100) or over part of the width of the part (case 600) gives the part a very good retention capacity.

[0067] In the examples described above, the continuous fiber layer is a strip with a 3D weave. The continuous fiber layer can also be a stack of unidirectional layers, a stack of two-dimensional woven layers unions, or even a braid.

[0068] The discontinuous fiber layer may be, in particular, a non-woven texture with long discontinuous fibers or a mat of random fibers.

Claims

Demands

1. A method for manufacturing a part of revolution made of composite material (100) exposed to impacts 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 production 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 fiber blank comprises a layer of continuous fibers corresponding to a strip-shaped fiber structure (70) having a three-dimensional weave, having in the longitudinal direction a first portion (76) in which the warp yarns are bound by the weft yarns over the entire thickness of the fiber structure and a second portion (75) comprising a debinding zone (71) present at an intermediate position in the thickness of the fiber structure and extending through the fiber structure in a plane parallel to the surface of the structure fibrous, the debonding zone (71) separating the fibrous structure into first and second skins (73, 74), a layer of discontinuous fibers being arranged between the first and second skins, and in which the realization of the fibrous structure includes winding the fibrous blank onto the mandrel in one or more turns.

6. A part of revolution made of composite material (100) exposed to impacts, the part 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. Part according to claim 8, wherein the fibrous reinforcement comprises a layer of continuous fibers corresponding to a band-shaped fibrous structure (70) having a three-dimensional or multi-layer weave comprising a first part (76) in which warp yarns are linked by 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, the debinding 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).