Fibrous texture for composite material casing including an omega stiffener

Abstract

Fibrous texture for a casing made of composite material comprising an omega stiffener Fibrous texture (100) having a three-dimensional weave between a plurality of layers of warp strands and a plurality of layers of weft strands. The fibrous texture (100) comprises at least one uncoupling (160) forming an internal housing (170) in the fibrous texture. The uncoupling extends, in a longitudinal direction (X), over a determined length (LT4) between an intermediate position (105) present between proximal and distal ends (102, 103) and the distal end (103) and, in the lateral direction, over a determined width (l140) less than the width (l100) of the fibrous texture (100) and set back from the first and second lateral edges (101, 102) of the fibrous texture. Figure for abstract: Fig. 2.

Description

Title of the invention: Fibrous texture for a composite material casing comprising an omega stiffener Technical field

[0001] The invention relates to gas turbine casings, and more particularly, but not exclusively, to gas turbine fan casings for aeronautical engines. Prior art

[0002] The manufacture of a casing made of composite material begins with the production of a fibrous texture in the form of a strip, the fibrous texture being produced by three-dimensional weaving between a plurality of layers of warp threads and a plurality of layers of weft threads. The fibrous texture thus obtained is wound over several turns on a mold or tool having the shape of the casing to be produced and held between the mold and segments forming a counter-mold so as to obtain a fibrous preform.

[0003] Once the fiber preform has been produced, that is to say at the end of the winding of the fiber texture, the tooling carrying the fiber preform is closed by counter-molds then transported to an oven or furnace in which the densification of the preform by a matrix is ​​carried out, the matrix being able to be obtained in particular by injection and polymerization of a resin in the fiber preform.

[0004] [Fig. 15] illustrates a fan casing 200 made of composite material obtained as described above. The fan casing 200 comprises upstream and downstream flanges 230 and 270 intended to be fixed respectively to an air inlet sleeve and to an intermediate casing shroud (not shown in [Fig. 8]). The casing 200 also comprises a retention zone 250 located between an upstream structural zone 240 and a downstream structural zone 260.

[0005] A fan housing serves three main functions, namely:

[0006] - ensure the connection of engine parts to each other,

[0007] - define the air inlet vein in the engine,

[0008] - provide retention by retaining ingested debris inside the engine, or blades or blade fragments projected by centrifugation, in order to prevent them from passing through the casing and reaching other parts of the aircraft.

[0009] The first two functions are not very demanding in terms of mechanical properties but are permanently active. On the other hand, the third function, even if it is very little used, is very demanding in terms of mechanical properties. For this purpose, the quantity, nature and arrangement of the fibers are defined in an optimized manner in the retention zone of the fan casing in order to be able to support an impact without rupture and retain blade fragments or ingested objects. An example of a composite fan casing with a reinforced retention zone is described in particular in document US 2020 / 271015. The retention zone corresponds to the heaviest part of the casing. The flanges are also thick because they are essential to ensure the holding of the interfaces and the absorption of forces with high stress gradients due to point bolted connections.

[0010] Consequently, the structural zones present between the flanges and the retention zone of the casing are the only ones that can be thinned. However, their thinning results in a reduction in mechanical strength in the structure of the casing which can be problematic in particular with regard to the dynamic behavior of the casing. Indeed, this thinning leads to the reduction of the natural frequencies of the fan casing and increases the risk of frequency crossover between one of its natural modes and the wake of the fan blades opposite the casing in the operating range of the engine. The casing then enters into resonance when one of its natural frequencies crosses an excitation harmonic produced by the wake of the blades, which can lead to the ruin of the casing.

[0011] Consequently, the fan casing must have minimal stiffness so as not to respond to vibrational excitations which are harmful to the engine, such as in the case, for example, of crossing with the wakes of the fan blades.

[0012] There are solutions in the prior art which aim to avoid the appearance of undesirable modes in a composite material casing. One solution, disclosed in particular in document US 2014 / 212273, consists of providing the composite material casing with added stiffeners. However, this solution results in a significant increase in the overall mass of the casing, in particular when it is a fan casing having a large diameter. It is also complicated to implement, in particular with regard to the fixing of the stiffeners which must be as reliable as possible.

[0013] Another solution, disclosed in document US 2017 / 266893, consists of stiffening a fan casing made of composite material by providing it with a portion having an omega profile. However, this solution results in a significant increase in the size and mass of the casing. Furthermore, due to its complex omega geometry, the production and installation of equipment (for example acoustic panels, abradable cartridges) on this type of casing proves to be tedious. Finally, the hollow formed by the omega portion must be filled with a material, which further penalizes the overall mass of the casing.

[0014] Thus, there is a need to improve the resistance of a composite material casing to vibration stresses without significantly increasing the mass and / or the size of the casing. Statement of the invention

[0015] For this purpose, the invention proposes a fibrous texture for fibrous reinforcement of a casing made of composite material having a strip shape extending in a longitudinal direction over a determined length between a proximal end and a distal end and in a lateral direction over a determined width between a first lateral edge and a second lateral edge, the fibrous texture having a three-dimensional weave between a plurality of layers of warp strands extending in the longitudinal direction and a plurality of layers of weft strands extending in the lateral direction, characterized in that the fibrous texture comprises at least one unlinking forming an internal housing in the fibrous texture, said at least one unlinking extending, in the longitudinal direction, over a determined length between an intermediate position present between the proximal and distal ends and the distal end and,along the lateral direction, over a determined width less than the width of the fibrous texture and set back from the first and second lateral edges of the fibrous texture.

[0016] The fibrous texture according to the invention makes it possible to produce composite material casings that are more resistant to vibration stresses. Indeed, the formation of at least one internal housing by debonding in the fibrous structure subsequently makes it possible to form a stiffener in the casing by shaping the internal housing of the fibrous structure which is used for producing the fibrous reinforcement of a composite material casing and thus to give the final casing the mechanical characteristics necessary for its functions and to reinforce the structural zones of the casing with respect to vibration stresses.

[0017] The fibrous texture according to the invention makes it possible to locally increase the stiffness of the casing without excessively increasing its mass and therefore to enhance the natural modes thereof to distance frequency coincidences outside the operating range. The casing therefore has improved modal strength, which makes it possible to avoid the appearance of undesirable vibration modes. In addition, the stiffening solution of the invention does not result in an increase in the mass of the casing.

[0018] The invention also relates to a fibrous preform for an aeronautical casing comprising a winding over several turns of a fibrous texture according to the invention, the internal housing formed by the delinking in the fibrous texture extending over the external turn of the winding of the preform, the fibrous preform comprising a preform part of a stiffening portion formed by the shaped internal housing.

[0019] According to a particular characteristic of the preform of the invention, the housing internally contains a bladder inflated by fluid or expanded material.

[0020] According to another particular characteristic of the preform of the invention, the inflated bladder has an omega-shaped section in the lateral direction.

[0021] The invention also relates to a gas turbine casing made of a composite material, comprising a fibrous reinforcement consisting of a fibrous preform according to the invention, and a matrix densifying the fibrous reinforcement. The casing may in particular be a gas turbine fan casing.

[0022] The invention also relates to a gas turbine aeronautical engine having a casing according to the invention.

[0023] The invention also relates to a method for manufacturing a fibrous texture by three-dimensional weaving between a plurality of layers of warp strands extending in a longitudinal direction and a plurality of layers of weft strands extending in the lateral direction, the fibrous structure having a strip shape extending in the longitudinal direction over a determined length between a proximal end and a distal end and in the lateral direction over a determined width between a first lateral edge and a second lateral edge,

[0024] characterized in that the method comprises producing at least one delink forming an internal housing in the fibrous texture, said at least one delink extending, in the longitudinal direction, over a determined length between an intermediate position present between the proximal and distal ends and the distal end and, in the lateral direction, over a determined width less than the width of the fibrous texture and set back from the first and second lateral edges of the fibrous texture.

[0025] The invention also relates to a method for manufacturing a fiber preform for an aeronautical casing comprising:

[0026] - the manufacture of a fibrous texture according to the method of manufacturing a texture fibrous material of the invention,

[0027] - winding the fibrous texture over several turns on a setting tool shape,

[0028] - shaping the internal housing in an omega shape so as to obtain a preform part of stiffening portion.

[0029] According to a particular characteristic of the method of the invention, the shaping of the internal housing is carried out by inflating a bladder present in the internal housing of the fibrous structure, the bladder being introduced into said internal housing before the winding of the fibrous structure on the shaping tool or during winding before the winding of the last turn of said fibrous structure comprising the unlinking forming the internal housing.

[0030] The invention finally relates to a method of manufacturing an aeronautical casing. comprising the manufacture of a fibrous preform according to the method of the invention and the densification of the preform by a matrix. Brief description of the drawings

[0031] [Fig.l] [Fig.l] is a schematic perspective view of a loom showing the three-dimensional weaving of a fibrous texture,

[0032] [Fig.2] [Fig.2] is a schematic perspective view of a fibrous texture in accordance with one embodiment of the invention,

[0033] [Fig.3] [Fig.3] is a partial side section of the fiber texture of [Fig.2] and showing a weave pattern with unbonding,

[0034] [Fig.4] [Fig.4] is a schematic perspective view showing the start of winding of the fibrous texture of [Fig.2] onto a shaping tool,

[0035] [Fig.5] [Fig.5] is a schematic perspective view showing the introduction of an inflatable bladder into the fibrous texture of [Fig.2] during winding,

[0036] [Fig.6] [Fig.6] is a partial side section of the fiber texture shown in [Fig.5] according to a weaving pattern,

[0037] [Fig.7] [Fig.7] is a partial side section of the fiber texture shown in [Fig.5] according to another weave pattern,

[0038] [Fig.8] [Fig.8] is a schematic perspective view showing the end of the winding of the fibrous texture after introduction of the inflation bladder,

[0039] [Fig.9] [Fig.9] is a half axial sectional view of the wound fibrous texture as shown in [Fig.8],

[0040] [Fig. 10] [Fig. 10] is a schematic perspective view of a casing preform,

[0041] [Fig. 11] [Fig. 11] is a half axial sectional view of the casing preform of [Fig.10],

[0042] [Fig. 12] [Fig. 12] is a sectional view showing the positioning of injection sectors on the preform of the casing of [Fig.10],

[0043] [Fig. 13] [Fig. 13] is a schematic perspective view of a composite material fan casing,

[0044] [Fig. 14] [Fig. 14] is a perspective view of an aeronautical engine in accordance with one embodiment of the invention,

[0045] [Fig. 15] [Fig. 15] is a half axial sectional view of an aircraft engine fan casing according to the prior art. Description of the embodiments

[0046] The invention applies generally to fibrous textures intended for the manufacture of casings made of composite material, these casings being subjected to vibratory phenomena.

[0047] The invention applies more particularly but not exclusively to the manufacture of fan casings which are subjected to vibratory stresses of different origins and with more or less significant levels. The dynamic response of a fan casing can reach very significant levels in the event of: - resonance with stresses synchronous with the rotation speed (functional interaction) - interaction with the fan blades corresponding to an asynchronous and unstable phenomenon (modal interaction)

[0048] In operation, the fan blades create dynamic excitations by their wake (rotating pockets of pressure and depression) which stress the casing without there being any contact. In this case, there is a synchronous phenomenon and a functional interaction.

[0049] The fan casing being a highly axisymmetric part, it responds to these forced stresses on one of its natural modes with Y diameters (“Y0”), i.e. the natural mode “A / Y0”, (“Y” corresponding to the number of fan blades of the turbomachine). The dynamic constraints of the casing in this mode can be prohibitive and quickly damage it by vibration fatigue.

[0050] In order to avoid a frequency coincidence between the excitations and the response of the casing and, consequently, the ruin of the casing with respect to these vibratory phenomena, it is ensured that the frequency coincidence between the engine harmonic YN (16N, 20N, 38N... depending on the number of fan blades) and the natural mode A / Y0 takes place outside the operating range and with a certain minimum margin.

[0051] This aim is achieved with the fibrous texture of the invention which makes it possible to increase the stiffness of the casing without excessively increasing the mass in the structural zones, which has the effect of increasing the margin.

[0052] As shown in [Fig. 1], a fibrous texture 100 is produced in a known manner by weaving using a jacquard type loom 5 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.

[0053] The fibrous texture is produced 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 threads bind warp threads over several layers of warp threads or vice versa. The fibrous texture may have an interlock weave. By "interlock" weave is meant here a weaving weave in which each layer of weft threads binds several layers of warp threads, with all the threads of the same weft column having the same movement in the plane of the weave. Other weaving weaves are conceivable.

[0054] As illustrated in [Fig.2], the fibrous texture 100 has a strip shape which extends in length in a longitudinal direction X corresponding to the direction of travel of the warp threads or strands 20 and in width or transversely in a lateral direction Y between a first and a second lateral edge 101 and 102, the lateral direction Y corresponding to the direction of the weft threads or strands 30. The fibrous texture extends longitudinally over a determined length LiOo in the direction X between a proximal end 103 intended to form the start of the winding of a fibrous preform on a shaping tool and a distal end 104 intended to form the end of the winding of the fibrous preform.

[0055] The length Li00 of the fibrous texture 100 is determined as a function of the circumference of the shaping tool or mold so as to allow a determined number of turns of the fibrous texture to be produced.

[0056] In the example described here, the fibrous texture 100 has a length LiOo allowing four turns of winding to be made on the shaping tool. For this purpose, the fibrous texture 100 comprises, along the longitudinal direction, four portions Ti to T4 having lengths Ln to LT4 respectively and corresponding respectively to the first, second, third and fourth turns of winding of the fibrous texture on the shaping tool. The length LT2 is slightly greater than the length Ln, the length LT3 is slightly greater than the length LT2 and the length LT4 is slightly greater than the length LT3 to take into account the increase in radius as the fibrous texture is wound.

[0057] The fourth portion T4 of the fibrous texture 100 which is intended to form the last turn or external turn of the winding on the shaping tool has from upstream to downstream (from the lateral edge 101 to the lateral edge 102 in [Fig. 2]) first to third portions 130, 140 and 150 each extending over the length LT4 of the fourth portion T4. The first portion 130 extends in the lateral direction Y over a determined width 1130 from the first lateral edge 101. The second portion 140 extends in the lateral direction Y over a determined width 1140 from the first portion 130. The third portion 150 extends in the lateral direction Y over a determined width 1150 from the second portion 140 and up to the second lateral edge 102.

[0058] The second portion 140 has a width li40 less than or equal to the width lno of the first portion 130 and less than the width l150 of the third portion. The third portion 150 has a width 1150 greater than the widths l130 and li40 of the first and second portions 130 and 140.

[0059] According to the invention, during weaving, a separation 160 is produced inside the second portion 140 between two successive layers of warp threads. The separation 160 extends along a plane parallel to the surface of the fiber blank and locally separates the fourth portion T4 into two woven portions 140a and 140b ([Fig.3]). The uncoupling 160 extends in the longitudinal direction X over a determined length corresponding to the length LT4 of the fourth portion T4 between an intermediate position 105 present between proximal and distal ends 102, 103 and the distal end 103. Furthermore, the uncoupling 160 extends in the lateral direction Y over a width corresponding to the width l140 of the second portion 140 set back from the lateral edges 101 and 102 of the fibrous texture 100 (i.e. the uncoupling 160 does not open onto the lateral edges 101 and 102) so as to maintain adjacent connecting portions corresponding to the first and third portions 130 and 150. The uncoupling 160 further opens onto the distal end 104 of the fibrous texture. The delinking 160 thus forms an internal housing 170 in the fourth portion T4 of the fibrous texture 100 which is accessible via the distal end 104 of the texture.

[0060] A 3D interlock weaving mode of the blank 100 is shown schematically in [Fig. 3]. [Fig. 3] is an enlarged partial view of a warp section plane in the fourth portion T4 of the blank 100 comprising the unlinking zone 160 (section III-III in [Fig. 2]). In this example, the blank 100 comprises 8 layers of warp threads 20 extending substantially in the longitudinal direction X. In [Fig. 3], the 8 layers of warp threads are linked by weft threads t1 to t8 in the linking zones of the first and third portions 130 and 150, the weft threads extending substantially in the lateral direction Y. At the level of the unlinking 160, the woven portion 140a comprises 4 layers of warp threads 20 linked together by 4 weft threads t1 to t4 while the woven portion 140b comprises the 4 layers of warp threads 20 linked together by 4 weft threads t5 to t8.

[0061] In other words, the fact that the weft threads t1 to t4 do not extend into the layers of warp threads of the woven portion 140b and that the weft threads t5 to t8 do not extend into the layers of warp threads of the woven portion 140a ensures the delinking 160 which separates the woven portions 113 and 114.

[0062] In the weaving example presented in [Fig. 3], the weft threads t1 to t4, on the one hand, and the weft threads t5 to t8, on the other hand, are respectively arranged on each side of the unlinking 160, the weft threads t1 to t4 binding the first four layers of warp threads forming the woven portion 140a and the weft threads t5 to t8 binding the last four layers of warp threads forming the woven portion 140b.

[0063] According to an alternative embodiment, a first portion of threads of the layers of weft threads can cross a second portion of threads of the layers of weft threads upstream and downstream of the uncoupling 160 in the lateral direction Y, the threads of the first portion of weft threads extending on one side of the uncoupling 160 in the lateral direction while the threads of the second portion of threads of the plurality of layers of weft threads extend on the other side of the uncoupling in the lateral direction. crossing the first and second parts of weft threads upstream and downstream of the uncoupling 160 in the Lateral Y direction makes it possible to improve the strength of the fibrous texture in the uncoupling zone.

[0064] The fibrous texture 100 of the invention makes it possible, after shaping, to form a fibrous casing reinforcement in which a stiffening portion is present in a structural zone of the casing, the stiffening portion being formed by the second portion 140 of the fibrous texture 100. The stiffness of the casing is thus locally increased, which makes it possible to enhance the natural modes of the casing and thus distance frequency coincidences outside the operating range.

[0065] An example has just been described in which the fiber texture has an interlock weave with 8 warp layers and 8 weft layers. However, the scope of the invention is not exceeded when the number of weft and warp layers is different, or when the fiber texture has a weave different from an interlock weave.

[0066] As illustrated in [Fig.4], the production of a fiber preform intended to constitute the fiber reinforcement of the casing begins with the winding onto a mandrel 50 of the fiber texture 100 described previously, the fiber reinforcement constituting a complete tubular fiber preform of a casing forming a single piece. For this purpose, the mandrel 50 has an external surface 51 whose profile corresponds to the internal surface of the casing to be produced. The mandrel 50 also comprises two flanges 52 and 53 to form upstream and downstream flange preform parts 63 and 66 corresponding to the flanges of the casing as illustrated in FIGS. 10 and 11.

[0067] The fibrous texture 100 is wound onto the mandrel 50 from its proximal end 103. One or more winding turns are made until the portion of the texture which comprises the internal housing 170 is reached. In the example described here, the portions T1, T2 and T3 of the fibrous texture 100 are first wound onto the mandrel 50 and then the winding is stopped in order to proceed with the introduction of an inflatable bladder 180 into the internal housing 170 present in the portion T4 as illustrated in [Fig. 5]. The inflatable bladder 180 introduced into the internal housing 170 has, in the lateral direction Y, an omega-shaped section as illustrated in [Fig. 6]. The bladder 180 is made of an elastic material such as, for example, high-temperature silicone or high-temperature rubber latex. The bladder 180 comprises a valve 181 allowing its inflation.According to an alternative embodiment, the inflatable bladder is introduced into the internal housing 170 of the fibrous texture 100 before the start of winding. In this case, winding can be carried out entirely without interruption.

[0068] According to an alternative embodiment illustrated in [Fig.7], a first part of threads of the layers of weft threads crosses a second part of threads of the layers of weft threads. in an area of ​​the fibrous structure located in the vicinity of the unlinking 160 and therefore of the internal housing 170. In the example illustrated in [Fig.7], the weft threads t3 and t4 are deflected at the start or upstream of the unlinking zone 160 to bind layers of warp threads in the portion 104b. Similarly, the weft threads t5 and t6 are deflected at the start or upstream of the unlinking zone 160 to bind layers of warp threads in the portion 104a. After the untying zone 160, the weft yarns t3 and t4 are again diverted at the end or downstream of the untying zone 160 to bind layers of warp yarns in the portion 104a while the weft yarns t5 and t6 are again diverted at the end or downstream of the untying zone 160 to bind layers of warp yarns in the portion 104b.The crossing of the weft threads t3 and t4 and the weft threads t5 and t6 upstream and / or downstream of the uncoupling zone 160 makes it possible to improve the holding of the fiber blank in the uncoupling zone and to limit the movements of the bladder 180 in the direction Y. According to an alternative embodiment, a portion of the weft threads can cross only upstream or downstream of the uncoupling zone 160.

[0069] Figures 8 and 9 illustrate the fiber texture 100 after introduction of the inflatable bladder into the internal housing 170 of the portion T4 and after complete winding of the texture 100 onto the mandrel 50. As shown in [Fig.9], the fiber texture 100 has 4 winding turns corresponding respectively to the portions Ti to T4, the portion T4 present on the external surface of the winding comprising the inflatable bladder 180 in the internal housing 170. .

[0070] A fluid or an expansive material 190 is then introduced into the bladder 180 by means of the valve 181 ([Fig. 10]). In the case of a fluid, this may be a gas such as air or a liquid which may be removed at the end of manufacture of the casing. In the case of an expansive material, this may in particular be an intumescent material such as for example an epoxy adhesive foam FM® 410 marketed by the company Solvay. In the case of an intumescent material, this is heated after its introduction into the bladder. As soon as a certain temperature is reached, the intumescent material will expand, forming bubbles in all directions which will exert pressure against the internal wall of the bladder and thus cause it to swell. Once expanded, the material can no longer be removed from the bladder which is then thus preserved in the final part.

[0071] Once the bladder 180 is inflated, a fibrous preform 60 is obtained, as illustrated in [Fig. 1 1], which will constitute the fibrous reinforcement of the composite material casing. The preform 60 comprises a stiffening portion preform part 63 formed by the internal housing 170 shaped by the inflation of the bladder 180. The stiffening portion preform part 63 has an omega shape in lateral section and extends over the entire external periphery of the preform 60.

[0072] The preform 60 also comprises an upstream flange preform portion 63, a retention zone preform portion 64 and a downstream flange preform portion 66.

[0073] The fibrous preform 60 is then densified using a matrix.

[0074] The densification of the fiber preform consists of filling the porosity of the preform, in all or part of its volume, by the material constituting the matrix.

[0075] The matrix can be obtained in a manner known per se using the liquid method. 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, optionally 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 [Fig. 12], the fibrous preform 60 is here placed between a plurality of sectors 54 forming a counter-mold and the mandrel 50 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 throughout the housing to impregnate the preform.

[0076] 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 still being 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.

[0077] In the case of the formation of a carbon matrix, the heat treatment consists of pyrolyzing the organic precursor to transform the organic matrix into a carbon matrix. For example, liquid carbon precursors may be resins with a relatively high coke content, such as phenolic resins. Several consecutive cycles, from impregnation to heat treatment, may be carried out to achieve the desired degree of densification.

[0078] 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 part made of rigid material and the mold and which includes the fiber preform. A pressure gradient is generally established in this internal space between the place where the resin is injected and the orifices for discharging the latter in order to control and optimize the impregnation of the preform by the resin.

[0079] The resin used may 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.

[0080] After injection and polymerization, the part is demolded. The part is finally trimmed to remove excess resin and the chamfers are machined to obtain a casing 810 having a revolution shape as illustrated in [Fig. 13]. The casing 810 comprises an upstream flange 811, a retention portion 813 and a downstream flange 814. According to the invention, the casing further comprises a stiffener 812 formed by the stiffening portion preform part 63. The stiffener 812 has an omega shape in lateral section and extends over the entire external periphery of the casing 810. In the example described here, the bladder has been inflated with a shrinkable fluid, such as air for example. In this case and after being deflated, the bladder can be extracted from the stiffener 812 through an opening 8120 machined in the stiffener.

[0081] The casing 810 shown in [Fig. 13] is a casing of a fan of an aeronautical gas turbine engine 80. Such an engine, as shown very schematically by [Fig. 14] comprises, from upstream to downstream in the direction of the gas flow, a fan 81 arranged at the inlet of the engine, a compressor 82, a combustion chamber 83, a high-pressure turbine 84 and a low-pressure turbine 85. The engine is housed inside a casing comprising several parts corresponding to different elements of the engine. Thus, the fan 81 is surrounded by the casing 810.

[0082] In the example described above, the fibrous texture used to form the fibrous reinforcement of the composite material casing comprises a single internal housing into which a bladder is introduced. The invention is however not limited to this single configuration of housing and inflatable bladder. The fibrous texture may in particular comprise a plurality of independent internal housings each comprising an access allowing a bladder to be introduced. In this case, the winding of the fibrous texture is stopped as soon as the start of a first internal housing is reached in order to introduce a first bladder therein, then the part of the fibrous texture comprising the first internal housing is wound with the first bladder.The fibrous texture is continued to be wound until the start of a second internal housing is reached, into which a second bladder is introduced, and then the part of the fibrous texture comprising the second internal housing is wound with the second bladder. These operations are repeated for the other housings, if any. According to a variant, the inflatable bladders are introduced into the internal housings of the fibrous texture. before the start of winding. In this case, the winding can be completed completely without interruption.

Claims

Claims

1. Fibrous preform (60) of an aeronautical casing (810) made of composite material comprising a winding over several turns of a fibrous texture (100), the fibrous texture having a strip shape extending in a longitudinal direction (X) over a determined length (Lu») between a proximal end (103) and a distal end (104) and in a lateral direction (Y) over a determined width (lioo) between a first lateral edge (101) and a second lateral edge (102), the fibrous texture having a three-dimensional weave between a plurality of layers of warp strands (20) extending in the longitudinal direction and a plurality of layers of weft strands (30) extending in the lateral direction, characterized in that the fibrous texture (100) comprises at least one uncoupling (160) forming at least one internal housing (170) in the fibrous texture, said at least one uncoupling extending, in the longitudinal direction,over a determined length (LT4) between an intermediate position (105) present between the proximal and distal ends (102, 103) and the distal end (103) and, in the lateral direction, over a determined width (l140) less than the width (lioo) of the fibrous texture and set back from the first and second lateral edges (101, 102) of the fibrous texture, said at least one internal housing (170) formed by the uncoupling (160) in the fibrous texture (100) extending around the outer circumference of the winding of the preform, the fibrous preform comprising a stiffening portion preform part (64) formed by the shaped internal housing and in that said at least one internal housing (170) encloses a bladder (180) inflated by a fluid or an expanded material (190).,

2. A fibrous preform according to claim 1, wherein the inflated bladder (180) has an omega-shaped section in the lateral direction (Y).

3. Gas turbine casing (810) made of a composite material, comprising a fibrous reinforcement consisting of a fibrous preform (60) according to claim 1 or 2, and a matrix densifying the fibrous reinforcement.

4. The housing (810) of claim 3, wherein said housing is a gas turbine fan housing.

5. A gas turbine aircraft engine (80) having a housing (810) according to claim 3 or 4.

6. Method for manufacturing a fibrous preform (60) of an aeronautical casing (810) comprising: - manufacturing a fibrous texture (100) by three-dimensional weaving between a plurality of layers of warp strands (20, 40) extending in a longitudinal direction (X) and a plurality of layers of weft strands (30) extending in the lateral direction (Y), the fibrous structure having a strip shape extending in the longitudinal direction (X) over a determined length (LiOo) between a proximal end (103) and a distal end (104) and in the lateral direction (Y) over a determined width (l100) between a first lateral edge (101) and a second lateral edge (102), manufacturing the fibrous texture comprising producing at least one unlinking (160) forming at least one internal housing (170) in the fibrous texture, said at least one unlinking extending, in the longitudinal direction, over a determined length (LT4) between an intermediate position (105) present between the proximal and distal ends (102,103) and the distal end (103) and, in the lateral direction, over a determined width (li40) less than the width (lioo) of the fibrous texture and set back from the first and second lateral edges (101, 102) of the fibrous texture, - winding the fibrous texture (100) over several turns on a shaping tool (50), - shaping the internal housing(s) (170) in an omega shape so as to obtain a stiffening portion preform part (64), a method in which the shaping of said at least one internal housing (170) is carried out by inflating a bladder (180) present in the internal housing of the fibrous structure (100), the bladder being introduced into said at least one internal housing before winding the fibrous structure onto the shaping tool (50) or during winding before winding the last turn of said fibrous structure comprising the unlinking (160) forming the internal housing (170).

7. A method of manufacturing an aeronautical casing (810) comprising manufacturing a fibrous preform (60) according to the method as defined in claim 6 and densifying the preform by a matrix.

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