Revolution part made of composite material with improved delamination resistance

Abstract

A process for manufacturing a part of revolution made of composite material with improved delamination resistance 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 a structural layer (50) having a three-dimensional weave and an interface fibrous texture (60) comprising polyamide or glass fibers, the interface fibrous layer having a thickness of less than 1 mm and a surface proportion of polyamide or glass fibers of less than 90%, the fibrous blank being shaped on the mandrel, said interface fibrous layer extending at least one full revolution around the mandrel (200). Figure for the abbreviation: Fig. 7.

Description

Title of the invention: Rotating part made of composite material with improved delamination resistance technical field

[0001] The present invention relates to the general field of manufacturing parts of revolution in composite material for propulsion assemblies such as gas turbine blower housings, air intakes or nacelle covers for aircraft 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, while a 3D woven texture inherently exhibits better impact resistance, the interfaces between adjacent towers of the 3D woven texture can constitute areas of weakness in the face of an impact. The same applies to an air intake or a nacelle cowling of a propulsion system. Description of the invention

[0006] It is therefore desirable to have a part of revolution made of composite material for a propulsion assembly exhibiting increased toughness at the level of the in interfaces between adjacent turns of the fibrous reinforcement of the part of revolution in order to increase its impact tolerance.

[0007] To this end, according to the invention, a method is proposed for manufacturing a part of revolution made of composite material for a propulsion assembly 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 a structural layer having a three-dimensional weave and an interface fibrous texture comprising polyamide or glass fibers, the interface fibrous texture having a thickness of less than 1 mm and a surface rate of polyamide or glass fibers of less than 90%, the fibrous blank being shaped on the mandrel, said interface fibrous texture 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 improved toughness at the interfaces between adjacent turns of the structural layer. The resulting composite material part exhibits increased retention capacity. The addition of a fibrous interface texture made of polyamide or glass fibers strengthens the bonding interface and dissipates more energy during an impact. A material more flexible (glass or polyamide fiber) than the carbon present in the three-dimensional fibrous texture causes existing cracks to bifurcate and stop. Crack stopping requires re-initiation and therefore more energy. Local crack bifurcations increase the crack path and thus the dissipated energy. This fibrous interface texture multiplies the cracks and therefore dissipates more energy through the thickness for a given surface area.The structural layer, for its part, ensures the cohesion and mechanical strength of the component.

[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 method of the invention, the fibrous interface texture is chosen from at least one of the following textures: two-dimensional woven, knitted, felted, voile, braided and matte.

[0011] According to another aspect of the process of the invention, the fibrous interface texture has a surface rate of polyamide fibers between 50% and 70%.

[0012] According to another aspect of the method of the invention, the fibrous blank is wound on n turns around the mandrel, the fibrous interface texture extending over n-1 turns around the mandrel. This allows a fibrous interface texture to be interposed between all adjacent turns of the preform and, consequently, of the fibrous reinforcement.

[0013] The invention also relates to a part of revolution made of composite material for a 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 two superimposed layers having a three-dimensional weave and an interface fibrous texture present at the interface between said at least two superimposed layers, the interface fibrous texture comprising polyamide or glass fibers, said interface fibrous texture further having a thickness of less than 1 mm and a surface rate of polyamide or glass fibers of less than 90%.

[0014] As explained above, the composite material part of the invention exhibits increased impact resistance compared to composite material parts of the prior art.

[0015] According to one aspect of the part of the invention, the fibrous interface texture is chosen from at least one of the following textures: two-dimensional woven, knitted, felted, voile, braided and matte.

[0016] According to another aspect of the part of the invention, the fibrous interface texture has a surface rate of polyamide or glass fibers between 50% and 70%.

[0017] 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

[0018] [Fig-1] [Fig. 1] is a perspective and partial cross-sectional view of an aircraft engine equipped with a fan casing made of composite material according to an embodiment of the invention,

[0019] [Fig.2] The [Fig.2] is a cross-sectional view along plane II-II of the housing of the [Fig.1],

[0020] [Fig.3] Fig.3 is a schematic perspective view of a loom showing the weaving of a three-dimensional fibrous structure used for forming the fibrous reinforcement of the casing in Figures 1 and 2,

[0021] [Fig.4] Fig.4 is a schematic perspective view of a fibrous structure 3D woven,

[0022] [Fig. 5] [Fig. 5] is a schematic perspective view of a fibrous texture interface,

[0023] [Fig.6] Fig.6 is a schematic perspective view of a fibrous blank formed with the 3D woven fibrous structure and the fibrous interface texture of the figures 4 and 5 according to one embodiment of the invention,

[0024] [Fig.7] The [Fig.7] is a schematic perspective view showing the shaping of the fibrous blank of the [Fig.6],

[0025] [Fig.8] The [Fig.8] is a cross-sectional view of a fibrous preform obtained from the fibrous blank of the [Fig.6],

[0026] [Fig.9] The [Fig.9] is a schematic view showing a densification tooling for the preform of the [Fig.8]. Description of the implementation methods

[0027] The invention applies generally to any part of revolution made of composite material for a propulsion assembly, the part of revolution being susceptible to impacts. Such parts for propulsion assemblies include, but are not limited to, gas turbine fan housings, nacelle air intakes, and nacelle cowlings found in aircraft engines.

[0028] The invention will be described below in the context of its application to a blower housing for an aeronautical gas turbine engine.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] The fibrous reinforcement is formed by winding a fibrous blank onto a mandrel, the mandrel having a profile corresponding to that of the housing to be produced. Advantageously, the fibrous reinforcement constitutes a complete tubular fibrous preform of the housing 100, forming a single piece with reinforcing portions corresponding to the flanges 104, 105.

[0035] According to the invention, the fibrous blank consists of a structural layer and an interface fibrous texture comprising polyamide or glass fibers.

[0036] The structural layer consists of a strip-shaped fibrous structure with 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 types of yarns can be used within the same preform. The fibrous structure is produced by three-dimensional weaving.By "three-dimensional weaving" or "3D weaving," we mean a weaving method in which at least some of the weft threads interlock with warp threads across multiple layers of warp threads, or vice versa. An example of three-dimensional weaving is interlocking. Interlocking weaving is a weave structure in which each layer of warp threads interlocks with multiple layers of weft threads, with all the threads 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 strip shape with 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 of the strip using weft yarns. The fibrous structure 50 extends over a width l50 defined according to the width of the housing to be manufactured, the width l50 being, for example, 2 m, and over a length L50 defined according to the diameter of the housing to be manufactured and the desired number of turns in the fibrous reinforcement. As an example, to manufacture a cylindrical housing with a diameter of 4 m by making 2 rough turns, the length of the fibrous structure to be woven is approximately 25 m. The length can be extended to avoid the beginning and end of the fibrous structure do not end up in the same angular position, which could create a weakness in the part.

[0039] In the example described here, the fibrous interface texture is a thin layer of polyamide fibers. Its thickness, which defines the thickness of the interface between the layers or turns of the structural layer, is between 0.02 mm and 1 mm.

[0040] Regarding the proportion of polyamide or glass fibers present in the fibrous interface layer, we will refer here to the "fiber surface content" rather than the "fiber volume content" given the thinness of the interface layer. Since this is a two-dimensional fibrous interface texture, we speak of the fiber surface content rather than the fiber volume content. This surface content corresponds to the proportion of the surface occupied by the fibers in the plane of the interface texture, the remaining surface being empty before injection and filled with resin after injection.

[0041] According to the invention, the fibrous interface layer has a surface area of ​​polyamide or glass fibers of less than 90%. Indeed, the fibrous interface layer must remain sufficiently aerated so as not to impede the passage of the resin during the densification of the preform and not to form a preferred weak point in a given crack plane that could reduce the dissipated energy and therefore the impact strength.

[0042] The surface percentage of polyamide or glass fibers in the fibrous interface texture is preferably between 50% and 70% because it allows for further optimization of the mechanical performance of the bonding interfaces between two woven layers.

[0043] The fibrous interface layer can have various types of texture, including a two-dimensional weave, a knit, a felt, a veil, a braid, or a mat.

[0044] In the example described here, the fibrous interface texture is a two-dimensional or 2D woven textile. Figure 5 illustrates a fibrous interface texture 60 consisting of a 2D woven strip comprising polyamide or glass fibers 61 randomly distributed over a thickness E60 of less than 1 mm. In the example described here, the fibrous interface texture 60 has a width l60 equivalent to the width l50 of the fibrous structure 50 and a length L60 less than the length L50 of the fibrous structure 50, such that only the fibrous structure 50 is present in the last winding of the fiber blank.

[0045] A fibrous blank 140 is then produced by placing the interface fibrous texture 60 onto the 3D woven fibrous structure 50 as illustrated in [Fig. 6]. A stitching step of the assembly edges between the interface fibrous texture 60 and the fibrous structure 50 can also be performed to hold them in position within the fibrous blank 140. The fibrous blank 140 can be compacted to reduce the profusion before its winding.

[0046] As illustrated in [Fig. 7], a fibrous preform is then formed by winding the fibrous blank 140 onto a mandrel 200 in a direction SR, with the fibrous structure 50 positioned against the mandrel 200. The mandrel has 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 it onto 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.

[0047] Fig. 8 shows a cross-sectional view of the fibrous preform 300 obtained after winding the fibrous blank 140 in several layers on 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 equal to 2. In the example described here, the preform 300 comprises, along the direction of its thickness, two layers or turns 51 and 52 of fibrous structure 50 and two layers or turns 62 and 63 of fibrous interface texture 60, the layer or turn 62 being interposed between the adjacent layers or turns 51 and 52 while the layer or turn 63 is present on the external periphery of the preform 300. The fibrous preform 300 also comprises end parts 320, 330 corresponding to the flanges 104, 105 of the housing.

[0048] The fibrous preform 300 is then densified by a matrix.

[0049] 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.

[0050] The matrix can be obtained in a manner known per se following the liquid-based process.

[0051] 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.

[0052] The transformation of the precursor into an organic matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after elimination The preform is continuously held in the mold, which has a shape corresponding to that of the part to be produced, after the solvent has been removed and the polymer crosslinked. The organic matrix can be obtained from epoxy resins, such as, for example, high-performance epoxy resins, or from liquid precursors of carbon or ceramic matrices.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 or turns 51 and 52 of fibrous structure 50 and two layers or turns 62 and 63 of interface fibrous texture 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 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 fibrous texture interface 60 is a function of the number of interfaces in the preform whose toughness we wish to reinforce.The 100 housing thus presents greater resistance to delamination due to the presence of a fibrous interface texture. between the turns of the 3D woven fibrous structure and, consequently, a greater capacity to retain debris, particles or objects ingested at the engine inlet, or originating from damage to blower blades, and projected radially by blower rotation.

[0057] The manufacturing process described above in relation to a fan housing for an aeronautical gas turbine engine also applies to the manufacture of other parts of revolution in composite material for propulsion assemblies such as nacelle air inlets or nacelle cowlings.

Claims

Claims

1. Method for manufacturing a composite material revolution part (100) for a propulsion assembly comprising: - producing a fiber preform (300) on a mandrel (200) having a profile corresponding to that of the part to be manufactured, and - densifying the fiber preform (300) by a matrix, characterized in that producing the fiber preform comprises forming a fiber blank (140) in the form of a strip comprising a structural layer (50) having a three-dimensional weave and an interface fiber texture (60) comprising polyamide or glass fibers, the interface fiber texture having a thickness of less than 1 mm and a surface rate of polyamide or glass fibers of less than 90%, the fiber blank being shaped on the mandrel (200), said interface fiber layer extending at least over one complete turn around the mandrel.

2. The method of claim 1, wherein the interface fibrous texture (60) is selected from at least one of the following textures: two-dimensional woven, knit, felt, veil, braid and mat.

3. Method according to claim 1 or 2, in which the interface fibrous texture (60) has a surface rate of polyamide or glass fibers of between 50% and 70%.

4. A method according to any one of claims 1 to 3, wherein the fibrous blank is wound over n turns on the mandrel, the interface fibrous texture (60) extending over n-1 turns around the mandrel.

5. Revolutionary part made of composite material (100) 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 two superimposed layers having a three-dimensional weave and a fibrous interface texture present at the interface between said at least two superimposed layers, the fibrous interface texture comprising polyamide or glass fibers, said fibrous interface texture furthermore having a thickness of less than 1 mm and a surface rate of polyamide or glass fibers of less than 90%.

6. A part according to claim 5, wherein the interface fibrous texture corresponds to at least one of the following textures: two-dimensional woven, knit, felt, veil, braid and mat.

7. Part according to claim 5 or 6, in which the interface fibrous texture has a surface rate of polyamide or glass fibers of between 50% and 70%.

8. Part according to any one of claims 5 to 7, the part corresponding to a casing (100) comprising a ferrule comprising a portion of excess thickness forming a retention zone, the ferrule further comprising at its axial ends a flange (104, 105).

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