Reinforcing fibrous texture for a composite material part with improved impact resistance and its manufacturing process

Abstract

A fibrous reinforcement texture for a composite material part with improved impact resistance and its manufacturing process. A fibrous reinforcement texture (10) for a composite material part has a three-dimensional weave between layers of warp yarns (C1-C8) juxtaposed over several columns of warp yarns (CC1-CC7) and layers of weft yarns (T1-T3). Each warp yarn has a determined initial fiber volume ratio and a count k corresponding to the number in thousands of filaments present in one warp yarn. The warp yarns are twisted yarns. The width (lCCH) of each column of warp yarns (CC1-CC7) is between 1.8 times and 2.2 times a value, the value a being calculated from the following formula: with: filament diameter of the warp yarns or strands; target fiber volume ratio of the warp yarns or strands. Figure for the abstract: Fig. 4.

Description

Title of the invention: Reinforcing fibrous texture for a composite material part with improved impact resistance and its manufacturing process. Technical field

[0001] The invention relates to fibrous textures comprising a three-dimensional or multilayer weave used to form fibrous reinforcements in composite materials. Prior art

[0002] One application of the invention is the production of parts made of structural composite material, that is, structural parts with fiber reinforcement and densified by a matrix. Composite materials make it possible to produce parts with a lower overall mass than the same parts when made of metallic material. In the field of aircraft engines, composite materials contribute to optimizing the performance of turbomachinery, particularly by reducing the overall mass of the turbomachine, which contributes to lower fuel consumption and therefore to a significant reduction in pollutant emissions. Furthermore, when made of thermostructural composite material, the parts allow for higher operating temperatures, which improves engine efficiency and further reduces fuel consumption.

[0003] The invention relates more particularly, but not exclusively, to composite material parts for aeronautical engines which are exposed to impacts such as fan or turbine blades, fan guide vanes of enclosed or unenclosed engines (open fan type engines) generally called OGVs (for "Outlet Guide Vane" in English), fan housings and external ferrules called "intermediate housing ferrule" or "VCI".

[0004] The fibrous reinforcement of composite material parts exposed to impacts is generally achieved by three-dimensional (3D) weaving between a plurality of warp yarn layers and a plurality of weft yarn layers, as this method, in particular, exhibits a non-delaminating characteristic capable of significantly increasing the impact resistance of the part. The fibrous reinforcement is produced from a 3D woven fibrous texture that is compacted to obtain a fibrous preform with a determined fiber volume ratio; the fibrous preform is then densified by a matrix.

[0005] US document 2005 / 084377 discloses a reinforcement structure, or preform, for a turbomachine blade, in particular a blower blade, by three-dimensional interlock weaving.

[0006] While the use of a fibrous reinforcement made by 3D weaving is an interesting solution, there is a need to further improve the impact resistance of composite material parts made from such a fibrous reinforcement. Description of the invention

[0007] To this end, the invention proposes a reinforcing fibrous texture for a part made of composite material, the fibrous texture having a three-dimensional weave between layers of warp yarns or strands juxtaposed over several columns of warp yarns or strands in the thickness of the fibrous texture and layers of weft yarns or strands juxtaposed over several columns of weft yarns or strands in the thickness of the fibrous texture, each warp yarn or strand having a determined initial fiber volume ratio TVFi and a count k corresponding to the number in thousands of filaments present in a warp yarn or strand, characterized in that the warp yarns or strands are twisted yarns and in that the width of each column of warp yarns is between 1.8 times and 2.2 times a value a, the value a being calculated from the following formula:

[0008] with d: diameter of the filaments of the warp wires or strands

[0009] TVFc; target fiber volume ratio of warp yarns or strands.

[0010] The fibrous texture of the invention thus has a column width of yarns or The warp strands are defined as a function of a target fiber volume ratio of the warp yarns or strands, that is, the fiber volume ratio of the warp yarns or strands obtained after compaction of the fibrous texture. As explained in detail below, the value 'a' allows the calculation of a column width of warp yarns or strands for which the warp density is optimal after compaction of the fibrous texture. The fibrous texture of the invention thus makes it possible to create fibrous reinforcements for composite material parts with improved impact resistance. Indeed, the increase in warp density, corresponding to the number of warp columns per cm², is directly linked to greater resistance to tearing or crack propagation, which is itself correlated with impact resistance.The density in the columns of warp wires or strands is maximal when the warp wires or strands have a cross-section whose compacted width corresponds to the width of the warp column.

[0011] According to a particular feature of the fibrous texture of the invention, the warp yarns or strands of the warp yarn or strand layers have a warp angle between 1° and 10°. As explained in detail below, with a warp angle between 1° and 10°, the fibrous texture according to the invention offers an excellent compromise between impact resistance and stiffness.

[0012] According to a particular feature of the fibrous texture of the invention, warp yarns or strands of each layer of warp yarns or strands have the same movement in a plane of the weave by linking together several layers of weft yarns or strands. This can correspond in particular to an interlock weave.

[0013] According to another particular feature of the fibrous texture of the invention, the warp yarns or strands and the weft yarns or strands are made up of filaments of carbon, glass, aramid or PBO Zylon® fibers.

[0014] According to another particular feature of the fibrous texture of the invention, the carbon filaments or filaments of another material have a cross-sectional diameter of between 5 µm and 5.4 µm, the width of each column of yarns or warp strands is between: - between 0.9 mm and 1.1 mm for wires or strands with a fineness of 12k, - between 1.35 mm and 1.65 mm for wires or strands with a fineness of 24k, - between 1.66 mm and 2 mm for wires or strands with a fineness of 36k, - between 1.9 mm and 2.3 mm for wires or strands with a fineness of 48k, - between 2.34 mm and 2.9 mm for wires or strands with a fineness of 72k, - between 2.7 mm and 3.3 mm for wires or strands with a fineness of 96k.

[0015] The invention also relates to a composite material part having a fibrous reinforcing texture according to the invention, compacted and densified by a matrix. The part may, in particular, correspond to one of the following: fan blade, turbine blade, guide blade, fan casing, intermediate casing ferrule, counter brace, landing gear brake bar, and seat structure.

[0016] The invention also relates to an aeronautical gas turbine engine having a part made of composite material according to the invention.

[0017] The invention further relates to a method for manufacturing a reinforcing fibrous texture for a composite material part, the method comprising creating a fibrous texture by three-dimensional weaving between layers of warp yarns or strands placed side by side over several columns of warp yarns or strands within the thickness of the fibrous texture and layers of weft yarns or strands placed side by side over several columns of weft yarns or strands within the thickness of the fibrous texture, each warp yarn or strand having a determined initial fiber volume fraction TV Fi and a count k corresponding to the number in thousands of filaments present in a warp yarn or strand, characterized in that the warp yarns or strands are twisted yarns and in that the width (1Cch) of each column of yarns or warp strands (Cci-Cc?) is between 1.8 times and 2.2 times a value a, the value a being calculated from the following formula: a = i>l k (TVFi

[0018] with: diameter of the filaments of the warp wires or strands

[0019] TVFc; target fiber volume ratio of warp yarns or strands.

[0020] The method of the invention makes it possible to define the column width of wires or strands The warp density is determined based on a target fiber volume ratio of the warp yarns or strands, that is, the fiber volume ratio of the warp yarns or strands obtained after compaction of the fibrous texture. As explained in detail below, the value 'a' allows the calculation of a column width of warp yarns or strands for which the warp density is optimal after compaction of the fibrous texture. The fibrous texture of the invention thus makes it possible to create fibrous reinforcements for composite material parts with improved impact resistance. Indeed, the increase in warp density, corresponding to the number of warp columns per cm², is directly linked to greater resistance to tearing or crack propagation, which is itself correlated with impact resistance.The density in the columns of warp wires or strands is maximal when the warp wires or strands have a cross-section whose compacted width corresponds to the width of the warp column.

[0021] According to a particular feature of the process of the invention, the warp yarns or strands of the warp yarn or strand layers have a warp angle of between 1° and 10°. As explained in detail below, with a warp angle of between 1° and 10°, the fibrous texture according to the invention offers an excellent compromise between impact resistance and stiffness.

[0022] According to a particular feature of the process of the invention, warp yarns or strands of each layer of warp yarns or strands have the same movement in a plane of the weave by linking together several layers of weft yarns or strands. This can correspond in particular to an interlock weave.

[0023] According to another particular feature of the process of the invention, the warp yarns or strands and the weft yarns or strands are made of carbon fiber filaments of glass, aramid or PBO Zylon®.

[0024] According to another particular feature of the process of the invention, the carbon filaments have a cross-sectional diameter of between 5 µm and 5.4 µm, the width of each column of warp wires or strands is: - between 0.9 mm and 1.1 mm for wires or strands having a fineness of 12k, - between 1.35 mm and 1.65 mm for wires or strands having a fineness of 24k, - between 1.66 mm and 2 mm for wires or strands with a fineness of 36k, - between 1.9 mm and 2.3 mm for wires or strands with a fineness of 48k, - between 2.34 mm and 2.9 mm for wires or strands with a fineness of 72k, - between 2.7 mm and 3.3 mm for wires or strands with a fineness of 96k. Brief description of the drawings

[0025] [Fig-1] The figure is a schematic perspective view of a loom showing the three-dimensional weaving of a fibrous texture,

[0026] [Fig.2] [Fig.2] shows a cross-sectional plan of a weave structure of the fibrous texture of [Fig.1] according to an embodiment of the invention,

[0027] [Fig.3] [Fig.3] shows another plan of a warp-section weave of the fibrous texture of [Fig.1] according to one embodiment of the invention,

[0028] [Fig.4] [Fig.4] shows a cross-sectional plan of a weave structure of the fibrous texture of [Fig.1] before compaction of said fibrous texture according to an embodiment of the invention,

[0029] [Fig.5] [Fig.5] shows the weave pattern in cross-section of [Fig.4] after compaction of the fibrous texture according to an embodiment of the invention,

[0030] [Fig.6] The [Fig.6] is a cross-section showing the section of a warp wire or strand before compaction,

[0031] [Fig.7] [Fig.7] is a cross-section showing the section of the warp wire or strand of [Fig.6] after compaction,

[0032] [Fig.8] Fig.8 is a curve showing the result of stiffness calculations as a function of the warp thread angle,

[0033] [Fig.9] Fig.9 is a curve showing the evolution of the width of a yarn with a fineness of 12k as a function of its intra-wire fiber content,

[0034] [Fig. 10] The [Fig. 10] is a curve showing the evolution of the width of a yarn having a fineness of 24k as a function of its intra-wire fiber content,

[0035] [Fig. 11] The [Fig. 11] is a curve showing the evolution of the width of a yarn having a fineness of 36k as a function of its intra-wire fiber content,

[0036] [Fig. 12] The [Fig. 12] is a curve showing the evolution of the width of a yarn having a fineness of 48k as a function of its intra-wire fiber content,

[0037] [Fig. 13] The [Fig. 13] is a curve showing the evolution of the width of a yarn having a fineness of 72k as a function of its intra-wire fiber content,

[0038] [Fig. 14] The [Fig. 14] is a curve showing the evolution of the width of a yarn having a fineness of 96k as a function of its intra-wire fiber content. Description of the implementation methods

[0039] The invention applies generally to the production of fibrous textures by three-dimensional weaving between layers of warp yarns or strands and layers of weft yarns or strands, the textures being intended to form fibrous reinforcements for composite material parts. The invention also applies to fibrous textures produced by two-dimensional weaving. For the sake of simplicity, the term "yarn" or "yarns" will be used in the remainder of this description.

[0040] The yarns used herein may include yarns made of carbon, glass, aramid, or PBO Zylon® fiber filaments, the invention not being limited to these types of yarns alone. The fibrous texture of the invention may also be woven with yarns made of filaments having different fiber types, such as, for example, with some yarns made of carbon fiber filaments and some yarns made of glass fiber filaments.

[0041] One application of the invention is the production of parts made of structural composite material, that is, structural parts with fiber reinforcement and densified by a matrix. The invention is advantageously applicable to the manufacture of parts made of organic matrix composite (OMC) material, without excluding other types of composite material. The parts referred to here are, in particular but not exclusively, composite material parts for aircraft engines or gas turbines that are likely to be exposed to shocks or impacts.

[0042] The process for manufacturing a composite fibrous texture according to the invention comprises, as shown in [Fig.1], the production of a fibrous texture 10 by three-dimensional weaving using a jacquard type loom 10 on which a bundle of warp strands or yarns FCH has been arranged in a plurality of layers, the warp yarns being linked by weft strands or yarns FTR.

[0043] The term “three-dimensional weaving” or “3D weaving” refers to a weaving method in which warp yarns interlock with weft yarns over several layers of warp yarns, or vice versa, so as to obtain a layer-by-layer interlacing distributed throughout the entire volume of the fibrous texture. An example of three-dimensional weaving is the so-called “interlock” weave. “Interlock” weaving refers to a weave structure in which each layer of warp yarns interlocks with several layers of weft yarns, with all the yarns in the same warp column having the same movement within the plane of the weave. However, weaves in which the warp yarns do not follow the same movement within the plane of the weave may also be used.

[0044] A 3D weave structure defines how the warp yarns interlace with the weft yarns and vice versa, following an elementary pattern for each plane of the weave structure. The weave structure pattern is defined on a plurality of warp cross-section planes, also called warp planes, which show the path of the yarns The warp and weft cross-sections are shown across the thickness of a fibrous texture for a given column of warp yarns—that is, the path of a warp yarn for each layer of warp yarns—as well as on a plurality of weft cross-sections, also called weft planes, which show the path of the weft yarns relative to the warp yarns (shown in cross-section) across the thickness of a fibrous texture for a given column of weft yarns—that is, the path of a weft yarn for each layer of weft yarns. The warp and weft cross-sections are repeated sequentially throughout the weaving of the fibrous texture.

[0045] Figures 2 and 3 represent two successive warp-section planes of a 3D weave structure of the fibrous texture 10, the representative pattern of which is defined on several warp planes parallel to each other along the direction of the weft yarns. In the example described here, the fibrous structure 10 comprises four layers of warp yarns Ci, C2, C3, and C4 extending substantially in a principal direction DP and four layers of weft yarns distributed into eight half-layers of weft yarns Tb T2, T3, T4, T5, T6, T7, and T8 arranged in a staggered pattern. The FTR weft yarns of the weft yarn layers Ti to T8 are juxtaposed on several columns of weft yarns CTi to CT7 within the thickness of the fibrous texture.

[0046] According to the invention, the weave used to create the fibrous texture is defined such that weft yarns in each layer of weft yarns bind several layers of warp yarns together with an alternation between two weave planes of the weft yarn layers that are bound within the thickness of the fibrous texture. This alternation, combined with the distribution of the bonding zones in the weave pattern, allows for the interlacing of all yarns throughout the entire elementary representative volume. Thus, there is no crack propagation path that is not blocked by a reinforcing yarn.

[0047] Figures 2 and 3 show the interlacing of FTR weft yarns by warp yarns 11, 21, 31, and 41 belonging respectively to warp yarn layers Ci to C4. In the weave plane of [Fig. 2], a warp yarn 11 belonging to warp yarn layer Cl links together FTR weft yarns belonging to three weft yarn layers (half-weft yarn layers T2 to T4). In the following weave plane illustrated in [Fig. 3], a warp yarn 11 belonging to warp yarn layer Ci links together FTR weft yarns belonging to three weft yarn layers with an offset of the linked weft yarn layers in the thickness of the fibrous texture (half-weft yarn layers Ti to T3). The same is true for warp yarns 21, 31, and 41 belonging respectively to warp yarn layers C2, C3, and C4.

[0048] The weave structure is preferably defined such that each warp yarn FCh connects three layers of weft yarns. A 3D weave structure The only known method allowing such a connection is the layer-by-layer weave called "interlock". By "interlock" weave, we mean a weave structure in which each layer of warp yarns connects several layers of weft yarns with all the yarns in the same warp column having the same movement in the plane of the weave and vice versa.

[0049] According to the present invention, the width of each warp yarn column is determined to provide a high yarn density in the warp direction, thereby maximizing tear resistance. Indeed, increasing the warp density, corresponding to the number of warp yarn columns per cm², is directly related to greater tear resistance, which is itself correlated with impact resistance.

[0050] The density in the warp yarn columns is maximized when the warp yarns have a cross-section whose compacted width corresponds to the width of the warp column. This warp density must, however, be optimized because if the width of the uncompacted warp yarn or strand is greater than the spacing allocated to the warp column in the 3D weave, weaving will not be possible due to warp yarn congestion in the loom and yarn-to-yarn friction during the heddle movements for sheaf opening.

[0051] According to the invention, each warp yarn is a twisted yarn, that is, a yarn whose filaments, and in particular those at its periphery, extend around said yarn along a helical path. Such a twisted yarn retains its initial perimeter when subjected to a compaction force tending to flatten it, as is the case during the compaction of the fibrous texture. Consequently, the fiber volume ratio of a twisted yarn naturally increases with the flattening of its cross-section.

[0052] As illustrated in [Fig. 6], each warp yarn or strand FCH consists of a plurality of filaments f, for example carbon fibers, and in its free state, i.e., after weaving and before compaction, has a circular cross-section of diameter DR, as is the case, in particular, with twisted yarns or strands. Each warp yarn or strand also has an intra-yarn fiber volume fraction of 50%.

[0053] Figure 7 represents the warp yarn FCH of Figure 6 after compaction of the fibrous texture. After compaction, the warp yarn FCh has an elliptical shape at constant perimeter, the largest dimension of which corresponds to twice the value a of the major axis of the ellipse, the minor axis of the ellipse being denoted b. Although represented in Figure 7 with a substantially elliptical shape, the filaments f actually have a more circular shape within the warp yarn, which itself does indeed have an elliptical shape.

[0054] Figures 4 and 5 represent a cross-sectional plane of the weave of the 3D woven structure of the fibrous texture 10 respectively before and after compaction of the texture fibrous. In the example described here, the fibrous structure 10 comprises three layers of weft yarns Tb, T2, and T3 extending substantially, and four layers of warp yarns distributed into eight half-layers of warp yarns Ci, C2, C3, C4, C5, C6, C7, and C8 arranged in a staggered pattern. The warp yarns FCH of the warp yarn layers Ci to C8 are juxtaposed on several columns of warp yarns Cci to Cc? within the thickness of the fibrous texture, each warp yarn column having a width 1Cch corresponding to the spacing allocated to each warp yarn column in the 3D weave.

[0055] In [Fig. 4], it can be seen that the warp yarns FCH, before compaction of the fibrous texture 10, have a circular shape as described previously in relation to [Fig. 6]. In their free or uncompacted state, the warp yarns FCh do not optimally occupy the width 1Cch of each warp yarn column. However, as illustrated in [Fig. 5], these same warp yarns FCh, after compaction of the fibrous texture 10, have an elliptical shape that optimally occupies the width 1Cch of each warp yarn column, in that the warp yarns each extend almost over the entire width 1Cch of each warp yarn column. In [Fig. 5], the warp yarns FCh present in each warp yarn column are shown with spaces between them. These spaces are shown for illustrative purposes only, to improve the visibility of the weave structure.In practice, in a compacted fibrous texture, the warp yarns in each warp column are very close to, or even in contact with, each other. Each warp yarn column thus exhibits a high warp density, both along the width and the height of each column.

[0056] This gives an optimal warp density after compaction ([Fig.5]) without risk of congestion of the warp yarns in the loom ([Fig.4]).

[0057] We now explain how the width of each column of warp threads is calculated in accordance with the invention.

[0058] The cross-sectional area of ​​a warp wire St is calculated using the following formula: v _ O2 with D corresponding to the diameter of the warp wire. — Æ 4

[0059] The sum Sf of the cross-sectional areas of the filaments present in a warp wire is calculated with the following formula: $ _ with A corresponding to the number in thousands of filaments per warp wire and d corresponding to the diameter of a filament.

[0060] In their free state, i.e., before compaction, the warp yarns have a circular cross-section and an initial intra-yarn fiber volume ratio TVFi. The intra-yarn fiber volume ratio corresponds to the volume of fibers constituting the yarn divided by the total volume of said yarn, i.e.:

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[0073] TVFi = Y with : • Sf corresponding to the sum of the cross-sectional areas of the filaments present in a warp thread, • St corresponding to the air of a warp thread in the free state. The perimeter Pi of a circular cross-section of a warp thread in its free state is calculated using the formula p = ttD, where D corresponds to the diameter of the warp thread. Therefore, if v ≥ -D², as seen above, then ≥ 1. — p-TTaV TV Fi In the compacted state, the cross-section of the warp yarns becomes oval while retaining their initial perimeter due to their twisting. Consequently, the intra-yarn fiber volume fraction naturally increases with compaction and ovalization of the warp yarn cross-section. For a given compaction rate of the fibrous texture, there is a target volume fraction of warp yarns (TVFc). The perimeter Pc of the cross-section of the warp threads in the compacted state corresponds to that of an ellipse which can be calculated as follows: Pt (V+F with a: major axis of the ellipse and b: minor axis of the ellipse. The area <SC de la section transversale d’un fil de chaîne à l’état compacté, c’est-à-dire présentant une section en forme d’ellipse, se calcule avec la formule suivante : Sc = Thus, the TVFc target fiber volume fraction of the warp yarns in the compacted state can be expressed as follows: with : • Sf corresponding to the sum of the cross-sectional areas of the filaments present in a warp thread, • Sc corresponding to the cross-sectional area of ​​a warp thread with an elliptical cross-section, • k corresponding to the number in thousands of filaments per warp thread, • d corresponding to the diameter of a filament. If TVFc = 4ab SO -- at - 4TVFc kd* AaTVFc

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[0091] Since the perimeter Pi of the cross-section of the warp threads in the free state, i.e., uncompacted, and the perimeter Pc of the cross-section of the warp threads in the compacted state are equivalent due to the twisting of the warp threads, we obtain the following formula: ^TVFÎ = 2^— with --, we obtain: “AaT VFc tlkl^^iaTTFë) ^\TVFi 2 which is equivalent to: kjn 2 k^d^ TVFia “2« + WTVFc2 which is equivalent to the following trinomial: U - a - 2TVFÎa + lôTVFc2 By setting x=2, the discriminant of the trinomial above is: A _ _ k2d4 / i 1 \ A - ^VF? ' ATVFc2 “ 4 ( TVFi2 " TVFc1 J If A > 0; "2 = + .......1...............1...... “4TVFi + 4 TVFi2 TVFc2 We then obtain the following formula (1): As indicated above, a corresponding to the major axis of the ellipse formed by the warp wires in the compacted state, formula (1) above thus allows us to calculate the width (the largest dimension) of the cross-section of the warp wires in the compacted state, equivalent to twice the value a, and this as a function of the volume ratio of TV Fi fibers of the warp wires in the free state and the volume ratio of TVFc fibers of the same warp wires in the compacted state. Therefore, for determined TVFi and TVFc fiber volume ratios, it is possible to calculate an optimal value for warp wire column width because this is directly related to the cross-sectional width of the warp wires in the compacted state. According to the invention, the width of each column of warp yarns in the fibrous texture is between 1.8 times and 2.2 times the value a, which corresponds respectively to -10% of 2a and +10% of 2a. Figures 9 to 14 are curves showing the evolution of the value 2a of a yarn or strand, that is, the variation in the width of the major axis a of the ellipse (Figure 7), obtained using formula (1), namely as a function of the TVFi fiber volume fraction of the warp yarns in the free state and the TVFc fiber volume fraction of the same warp yarns in the compacted state of its intra-yarn fiber volume fraction or intra-strand for yarns or strands with a fineness of 12k (Figure 9), 24k (Figure 10), 36k (Figure 11), 48k (Figure 12), 72k (Figure 13), and 96k (Figure 14), respectively. The fineness of a yarn or strand corresponds to its thickness (depending on the type of yarn, the density varies, so the volume occupied for the same mass will be different) and can be defined by the number of filaments it contains. In this case, the yarn fineness is expressed in "k," which corresponds to the number of filaments per yarn in thousands. For example, a 12k yarn contains 12,000 filaments, a 24k yarn contains 24,000 filaments, a 48k yarn contains 48,000 filaments, and so on. Each figure 9 to 14 includes three curves corresponding to an initial or free-state TV Fi fiber volumetric rate of 40%, 50% and 60% respectively.

[0092] The wires or strands used for the measurements taken on the curves in figures 9 to 14 are HexTow® IM7 carbon wires or strands whose unit filaments have an average diameter of 5.2 pm.

[0093] According to the curves in Figures 9 to 14, it can be seen, for example, that for an initial TV Fi fiber volume ratio of 50% and a target TVFc fiber volume ratio between 70% and 80%, the optimized 1Cch width for the channel columns is between:

[0094] - between 0.9 mm and 1.1 mm with 2a=l for wires or strands having a fineness of 12k,

[0095] - between 1.35 mm and 1.65 mm with 2^=1.5 for wires or strands having a fineness of 24k,

[0096] - between 1.66 mm and 2 mm with 2fl=l.84 for wires or strands having a fineness of 36k,

[0097] - between 1.9 mm and 2.3 mm with 2a=2.13 for wires or strands having a fineness of 48k,

[0098] - between 2.34 mm and 2.9 mm with 2a=2.61 mm for wires or strands having a fineness of 72k,

[0099] - between 2.7 mm and 3.3 with 2a=3 for wires or strands having a fineness of 96k.

[0100] According to another example, the value 2a of a wire or strand corresponding to the width of the The major axis a of the ellipse (Figure 7) was calculated using formula (1) for HexTow® IM10 carbon yarns or strands whose unit filaments have an average diameter of 4 pm. For example, it can be seen that, for an initial TVFi fiber volume percentage of 50% and a target TVFc fiber volume percentage of 75%, the optimized width 1Cch for the warp columns is:

[0101] - between 0.74 mm and 1.1 mm with 2a=0.9 for wires or strands having a fineness of 12k,

[0102] - between 1 mm and 1.28 mm with 2°=1.16 for wires or strands having a fineness of 24k,

[0103] - between 1.28 mm and 1.56 mm with 2^=1.42 for wires or strands having a fineness of 36k,

[0104] - between 1.48 mm and 1.8 mm with 2a=l.64 for wires or strands having a fineness of 48k,

[0105] - between 1.8 mm and 2.21 with 2a=2.01 for wires or strands having a fineness of 72k,

[0106] - between 2.1 mm and 3.3 with 2a=2.55 for wires or strands having a fineness of 96k.

[0107] According to another example, the value 2a of a wire or strand corresponding to the width of the major axis a of the ellipse (Figure 7) was calculated using formula (1), for wires or Torayca® Tl 100 carbon strands (marketed by Toray) whose individual filaments have an average diameter of 5.5 µm. For example, it can be observed that, for an initial TVFi fiber volume percentage of 50% and a target TVFc fiber volume percentage of 75%, the optimized 1CCH width for warp columns is:

[0108] - between 0.98 mm and 1.2 mm with 2^=1.09 for wires or strands having a fineness of 12k,

[0109] - between 1.4 mm and 1.7 mm with 2a=l.55 for wires or strands having a fineness of 24k,

[0110] - between 1.7 mm and 2.1 mm with 2a=l.89 for wires or strands having a fineness of 36k,

[0111] - between 2 mm and 2.4 mm with 2fl=2.19 for wires or strands having a fineness of 48k,

[0112] - between 2.4 mm and 2.94 with 2^=2.68 for wires or strands having a fineness of 72k,

[0113] - between 2.78 mm and 3.3 with 2fl=3.4 for wires or strands having a fineness of 96k.

[0114] According to another example, the value 2a of a wire or strand corresponding to the width of the major axis a of the ellipse (Figure 7) was calculated using formula (1), for S-2 Glass® wires or strands whose unit filaments have an average diameter of 9 pm. For example, it can be seen that, for an initial TVFi fiber volume ratio of 50% and a target TVFc fiber volume ratio of 75%, the optimized width 1Cch for the chain columns is:

[0115] - between 0.95 mm and 1.17 mm with 2a=l.06 for wires or strands having a fineness of 4k,

[0116] - between 1.35 mm and 1.65 mm with 2°=1.5 for wires or strands having a fineness of 8k,

[0117] - between 1.66 mm and 2.02 mm with 2a=l.84 for wires or strands having a fineness of 12k,

[0118] - between 1.9 mm and 2.53 mm with 2a=2.13 for wires or strands having a fineness of 16k,

[0119] - between 2.34 mm and 2.86 with 2a=2.60 for wires or strands having a fineness of 24k,

[0120] - between 2.71 mm and 3.3 with 2a=3.31 for wires or strands having a fineness of 32k.

[0121] The control of the width of the warp columns is carried out in a loom of the jacquard type such as the loom 10 of [Fig.l] used for the production of fibrous structures or fabric obtained by three-dimensional weaving between a plurality of layers of warp yarns FCH and a plurality of layers of weft yarns FTR.

[0122] As is known, the loom 10 is equipped with a Jacquard mechanism 11 supported by a superstructure not shown in [Fig. 1]. The loom 10 also includes a harness 20 consisting of a heddle board 21 and control wires or heddles 22, each heddle 22 being connected at one end to a control hook 12 of the Jacquard mechanism 11 and at the other end to one of the return springs 13 fixed to the frame 14 of the loom 10.

[0123] Each helix 22 includes an eyelet 23 through which a warp thread FCh passes. The helixes 22 and their associated eyelet 23 are animated by a substantially vertical oscillatory movement represented by the double arrow F under the tensile forces exerted. respectively by the control hooks 12 and the return springs 13. The heddles 22 allow some warp yarns FCH to be lifted and thus create a swarm 15 allowing the introduction of weft yarns FTR.

[0124] The rails 22 are spatially distributed according to the position of the holes 210 of the stacking board 21, that is to say along a plurality of columns 211 and rows 212.

[0125] The density of the holes 210 in the heddle board corresponds to the density of the fabric to be produced; that is, the spacing between each column of holes in the heddle board is equivalent to that between each warp column in the fabric to be produced. More precisely, when we want to weave with a specific width 1Cch for each column of warp yarns, the distance d2n between the columns 211 of the holes 210 in the heddle board 21 is adjusted to be equal to the width 1Cch determined as shown in [Fig. 1] for the warp yarn columns CC1 and CC2, which is then found in the woven fibrous texture ([Fig. 4]). For example, if we want to obtain a woven fibrous texture with ten layers of warp yarns with warp yarn columns having a width 1Cch of 2 mm, we adjust the distance d2n between the columns 211 of the holes 210 of the stacking board 21 to 2 mm.

[0126] To bind together several layers of weft yarns, each warp yarn follows a specific interlacing pattern that results in a waviness of each warp yarn in the fibrous texture. This waviness is called "waviness," and the angle formed between the waviness direction Do of a warp yarn and its principal direction DP in the fibrous texture is called the "waviness angle" (Figures 2 and 3). The waviness angle is a parameter that is determined primarily by the weaving conditions defined in the loom.

[0127] The warp angle induced by the warp undulation is a parameter that allows adjustment of the stiffness of the final composite material. The smaller the warp angle, the greater the stiffness of the resulting material. However, if the warp angle of the warp yarns is too small, it is not possible to interlace several layers of weft yarns and, consequently, to obtain a monolithic material without a preferred crack propagation path.

[0128] Figure 8 is a curve showing the result of stiffness calculations as a function of the splay angle. The calculations were performed using measurements taken on a plate-type specimen made of CMO composite material comprising a unidirectional (UD) fiber reinforcement, i.e., without splay. The measurements of the effect of fiber misorientation relative to the loading axis were taken in the plane. The results on the UD-reinforced CMO plate were used by making An analogy exists between the angle of embuvage and a disorientation in the plane, which is reflected in the curve of [Fig.8]. A significant drop in stiffness is observed when the angle of embuvage exceeds 10°.

[0129] Since the embouchure angle cannot be zero because that would mean that there is no interlacing, the embouchure angle of the warp yarns of the layers of warp yarns in the fibrous texture of the invention is between 1° and 10°.

[0130] Therefore, by using a 3D weave structure allowing the interlacing or bonding of several layers of weft yarns with a weft angle to warp yarns between 1° and 10°, an optimized compromise between impact resistance and stiffness is defined,

[0131] A fibrous texture defined as above can be advantageously used for the manufacture of a part in composite material, the fibrous texture being compacted at a compaction rate determined according to the desired volumetric fiber ratio in the fibrous reinforcement of the final part in composite material.

[0132] The manufacture of a part in composite material therefore includes at least the compaction of the fibrous texture, the shaping thereof (which can be carried out at the same time as the compaction) and the densification of the fibrous preform thus obtained.

[0133] The densification of the fibrous preform intended to form the fibrous reinforcement of the part to be manufactured consists of filling the porosity of the preform, in all or part of its volume, with the material constituting the matrix.

[0134] This densification can be achieved, in a known manner, by the liquid-based process (LBC, "LCM" in English). The liquid-based process consists of impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin, possibly diluted in a solvent.

[0135] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the injection tooling, after removal of any solvent and crosslinking of the polymer, the preform always being held in the molding cavity having a shape corresponding to that of the part to be produced.

[0136] 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 external shape of the part to be produced. A thermosetting resin is injected into the internal space of the mold containing the fibrous preform. A pressure gradient is generally established in this space. internal between the point where the resin is injected and the evacuation points of the latter in order to control and optimize the impregnation of the preform by the resin.

[0137] The resin used can be, for example, an epoxy resin with a temperature class of 180 °C (maximum temperature that can withstand it without loss of properties). 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.

[0138] After injection and polymerization, the part is demolded. Finally, the part can be trimmed to remove excess resin and the chamfers are machined.

[0139] Other known densification and / or matrix precursor processes can also be used to manufacture the part from composite material.

[0140] The invention applies in particular but not exclusively to the manufacture of composite material parts corresponding to one of the parts of aeronautical gas turbine engines such as fan or turbine blades, fan guide vanes of enclosed or unenclosed engines (open fan type engine) generally called OGV (for "Outlet Guide Vane" in English), fan housings, external ferrules called "intermediate housing ferrule" or "VCI", counter braces, landing gear brake bars and seat structures.

Claims

Demands

1. A fibrous reinforcement texture (10) for a composite material part, the fibrous texture having a three-dimensional weave between layers of warp yarns or strands (CrC8) juxtaposed over several columns of warp yarns or strands (CC1-CC7) in the thickness of the fibrous texture and layers of weft yarns or strands (TrT8) juxtaposed over several columns of weft yarns or strands (CTrCT7) in the thickness of the fibrous texture (30), each warp yarn or strand having a determined initial fiber volume ratio TV Fi and a count k corresponding to the number in thousands of filaments present in a warp yarn or strand, characterized in that the warp yarns or strands are twisted yarns and in that the width (1Cch) of each column of warp yarns or strands (CCrCC7) is between 1.8 times and 2.2 times a value a,the value a being calculated from the following formula: dh [ 1 / 1 1 1 a ~ 2 VÆ\ TVFi + yTVF? ' TVFc2 J with d ; diameter of the filaments of the warp wires or strands TVFc ; target fiber volume ratio of the warp wires or strands.,

2. Fibrous texture according to claim 1, wherein the warp yarns or strands (FCh) of the warp yarn or strand layers (CrC8) have a melting angle (a) between 1° and 10°.

3. Fibrous texture according to claim 1 or 2, wherein warp yarns or strands (WH) of each layer of warp yarns (CrC4) have the same movement in a plane of the weave by linking together several layers of weft yarns or strands.

4. Fibrous texture according to any one of claims 1 to 3, wherein the warp yarns or strands (FCh) and the weft yarns or strands (FTR) are made of filaments of carbon, glass, aramid, or PBO Zylon® fibers.

5. Fibrous texture according to claim 4, wherein the carbon filaments have a cross-sectional diameter between 5 pm and 5.4 pm and wherein the width (1Cch) of each column of warp yarns or strands (CC1-CC7) is: - between 0.9 mm and 1.1 mm for yarns or strands having a fineness of 12k, - between 1.35 mm and 1.65 mm for wires or strands with a fineness of 24k, - between 1.66 mm and 2 mm for wires or strands with a fineness of 36k, - between 1.9 mm and 2.3 mm for wires or strands with a fineness of 48k, - between 2.34 mm and 2.9 mm for wires or strands with a fineness of 72k, - between 2.7 mm and 3.3 mm for wires or strands with a fineness of 96k.

6. A composite material part having a fibrous reinforcement texture according to any one of claims 1 to 5, compacted and densified by a matrix.

7. Part according to claim 6, said part corresponding to one of the following parts: fan blade, turbine blade, guide blade, fan casing, intermediate casing ferrule, counter-brake, landing gear brake bar and seat structure.

8. Aeronautical gas turbine engine having a part made of composite material according to claim 6 or 7.

9. A method for manufacturing a reinforcing fibrous texture for a composite material part, the method comprising producing a fibrous texture (10) by three-dimensional weaving between layers of warp yarns or strands (CrC8) placed side by side over several columns of warp yarns or strands (CC1-CC7) in the thickness of the fibrous texture and layers of weft yarns or strands (Tr T8) placed side by side over several columns of weft yarns or strands (CTi-CT7) in the thickness of the fibrous texture, each warp yarn or strand having a determined initial fiber content TVFi and a count k corresponding to the number in thousands of filaments present in a warp yarn or strand, characterized in that the warp yarns or strands are twisted yarns and in that the width (1Cch) of each column of warp yarns or strands (CC1-CC7) is between 1.8 times and 2.2 times a value a, the value a being calculated from the following formula: d / .( 1 , r 1 1 \ « = 2\k\TVFÎ +\TVF? -TVW ) with d ; diameter of filaments of wires or warp strands TV Fc ; target fiber ratio of wires or warp strands.

10. A method according to claim 9, wherein the warp yarns or strands (FCh) of the warp yarn or strand layers (CrC8) have a splay angle (a) between 10 and 10°.

11. A method according to claim 9 or 10, wherein warp yarns (WY) of each layer of warp yarns or strands have the same movement in a plane of the weave by linking together several layers of weft yarns or strands (WY).

12. A method according to any one of claims 9 to 11, wherein the warp yarns or strands (WH) and the weft yarns or strands (Wt) are made of carbon fiber filaments of glass, aramid or PBO Zylon®.

13. A method according to any one of claims 9 to 12, wherein the carbon filaments have a cross-sectional diameter of between 5 µm and 5.4 µm and wherein the width (Icch) of each column of warp wires or strands (CC1-CC7) is: - between 0.9 mm and 1.1 mm for wires or strands having a fineness of 12k, - between 1.35 mm and 1.65 mm for wires or strands having a fineness of 24k, - between 1.66 mm and 2 mm for wires or strands having a fineness of 36k, - between 1.9 mm and 2.3 mm for wires or strands having a fineness of 48k, - between 2.34 mm and 2.9 mm for wires or strands having a fineness of 72k, - between 2.7 mm and 3.3 mm for wires or strands having a fineness of 96k.

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