Fibrous reinforcing texture for a part made of composite material with improved impact resistance, and method for manufacturing same

Abstract

A fibrous reinforcing texture (10) for a part made of composite material has three-dimensional weaving between juxtaposed layers of warp yarns (C1-C8) on several wales (CC1-CC7) of warp yarns and layers of weft yarns (T1-T3). Each warp yarn has a specific initial fiber volume ratio TVFi and a count k corresponding to the number of thousands of filaments present in a warp yarn. The warp yarns are twisted yarns. The width (ICCH) of each wale (Cc1-Cc7) of warp yarns is between 1.8 times and 2.2 times a value a, the value a being calculated using the following formula: (I), where d is the diameter of the filaments of the warp yarns or strands, and TVFc is the desired fiber volume ratio of the warp yarns or strands.

Description

[0001] Description

[0002] Title of the invention: Reinforcing fibrous texture for a composite material part with improved impact resistance and its manufacturing process

[0003] Technical Field

[0004] The invention relates to fibrous textures comprising a three-dimensional or multi-layer weave used to form fibrous reinforcements in composite materials.

[0005] Previous technique

[0006] One application of the invention is the production of parts made of structural composite materials, that is, structural parts reinforced with fibers 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 materials. 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 a significant reduction in pollutant emissions. Furthermore, when made of thermostructural composite materials, the parts allow for higher operating temperatures, which improves engine efficiency and further reduces fuel consumption.

[0007] 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".

[0008] The fiber reinforcement of composite parts exposed to impacts is generally achieved through three-dimensional (3D) weaving between multiple layers of warp yarns and multiple layers of weft yarns. This method, in particular, exhibits non-delaminating properties, significantly increasing the part's impact resistance. The fiber reinforcement is produced from a 3D woven fiber texture that is compacted to obtain a fiber preform with a specific fiber volume ratio. This fiber preform is then densified using a matrix.

[0009] US document 2005 / 084377 discloses a reinforcement structure, or preform, for a turbomachine blade, in particular a blower blade, by three-dimensional interlock weaving.

[0010] 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 fibrous reinforcement.

[0011] Description of the invention

[0012] 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: with d: diameter of the filaments of the warp threads or strands

[0013] TVFc: target fiber volume fraction of the warp yarns or strands. The fibrous texture of the invention thus has a warp yarn or strand column width that is defined as a function of a target fiber volume fraction of the warp yarns or strands, that is, the fiber volume fraction 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 warp yarn or strand column width 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 maximum when the warp wires or strands have a cross-section whose compacted width corresponds to the width of the warp column.

[0014] According to a particular feature of the fibrous texture of the invention, the warp yarns or strands of the layers of warp yarns or strands have a bending angle between 1° and 10°. As explained in detail below, with a bending angle between 1° and 10°, the fibrous texture according to the invention offers an excellent compromise between impact resistance and stiffness.

[0015] According to a particular feature of the fibrous texture of the invention, the warp yarns or strands of each layer of warp yarns or strands have the same movement in a plane of the weave, linking together several layers of weft yarns or strands. This can correspond, in particular, to an interlock weave.

[0016] 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.

[0017] 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 between 5 µm and 5.4 µm, the width of each column of yarns or warp strands is between:

[0018] - 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,

[0019] - between 1.66 mm and 2 mm for wires or strands with a fineness of 36k,

[0020] - between 1.9 mm and 2.3 mm for wires or strands with a fineness of 48k,

[0021] - between 2.34 mm and 2.9 mm for wires or strands with a fineness of 72k,

[0022] - between 2.7 mm and 3.3 mm for wires or strands with a fineness of 96k.

[0023] 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.

[0024] The invention also relates to an aeronautical gas turbine engine having a part made of composite material according to the invention.

[0025] The invention further relates to a method for manufacturing a reinforcing fibrous texture for a part made of composite material, the method comprising creating a fibrous texture by three-dimensional weaving 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 (ICCH) of each column of warp yarns or strands (Cci-Cc?) is between 1.8 times and 2.2 times a value a, the value a being calculated from the following formula: with d: diameter of the filaments of the warp threads or strands

[0026] TVFc: target fiber volume fraction of the warp yarns or strands. The process of the invention makes it possible to define the column width of the warp yarns or strands as a function of a target fiber volume fraction of the warp yarns or strands, that is, the fiber volume fraction 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 the 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 produce 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 maximum when the warp wires or strands have a cross-section whose compacted width corresponds to the width of the warp column.

[0027] 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 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.

[0028] According to a particular feature of the invention, the 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.

[0029] 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®.

[0030] 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, and the width of each column of threads or warp strands is:

[0031] - between 0.9 mm and 1.1 mm for wires or strands with a fineness of 12k,

[0032] - 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,

[0033] - between 1.9 mm and 2.3 mm for wires or strands with a fineness of 48k,

[0034] - between 2.34 mm and 2.9 mm for wires or strands with a fineness of 72k,

[0035] - between 2.7 mm and 3.3 mm for wires or strands with a fineness of 96k.

[0036] Brief description of the drawings

[0037] [Fig. 1] The figure is a schematic perspective view of a loom showing the three-dimensional weaving of a fibrous texture,

[0038] [Fig. 2] Figure 2 shows a cross-sectional plan of a weave structure of the fibrous texture of Figure 1 according to one embodiment of the invention,

[0039] [Fig. 3] Figure 3 shows another plan of a warp-section weave of the fibrous texture of Figure 1 according to one embodiment of the invention,

[0040] [Fig. 4] Figure 4 shows a cross-sectional plan of a weave structure of the fibrous texture of Figure 1 before compaction of said fibrous texture according to an embodiment of the invention,

[0041] [Fig. 5] Figure 5 shows the cross-sectional weave pattern of Figure 4 after compaction of the fibrous texture according to one embodiment of the invention,

[0042] [Fig. 6] Figure 6 is a cross-section showing the section of a warp wire or strand before compaction,

[0043] [Fig. 7] Figure 7 is a cross-section showing the section of the warp wire or strand of figure 6 after compaction,

[0044] [Fig. 8] Figure 8 is a curve showing the result of stiffness calculations as a function of the warp thread angle,

[0045] [Fig. 9] Figure 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,

[0046] [Fig. 10] Figure 10 is a curve showing the evolution of the width of a yarn with a fineness of 24k as a function of its intra-yarn fiber content, [Fig. 11] Figure 11 is a curve showing the evolution of the width of a yarn with a fineness of 36k as a function of its intra-yarn fiber content,

[0047] [Fig. 12] Figure 12 is a curve showing the evolution of the width of a yarn with a fineness of 48k as a function of its intra-wire fiber content,

[0048] [Fig. 13] Figure 13 is a curve showing the evolution of the width of a yarn with a fineness of 72k as a function of its intra-wire fiber content,

[0049] [Fig. 14] Figure 14 is a curve showing the evolution of the width of a yarn with a fineness of 96k as a function of its intra-yarn fiber content.

[0050] Description of the implementation methods

[0051] The invention applies generally to the creation 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 created by two-dimensional weaving. For the sake of simplicity, the term "yarn" or "yarns" will be used throughout this description.

[0052] The yarns used here may include yarns made of carbon fiber, glass fiber, aramid fiber, or PBO Zylon® 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 of different fiber types, such as, for example, with some yarns made of carbon fiber filaments and some yarns made of glass fiber filaments.

[0053] 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. The manufacturing process for a composite fibrous texture according to the invention comprises, as shown in Figure 1, the creation 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 is arranged in a plurality of layers, the warp yarns being linked by weft strands or yarns FTR.

[0054] By "three-dimensional weaving" or "3D weaving," we mean a weaving method in which warp yarns interlock with weft yarns across multiple layers of warp yarns, or vice versa, to create 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 multiple layers of weft yarns, with all yarns in the same warp column moving in the same direction within the weave plane. However, weaves in which the warp yarns do not move in the same direction within the weave plane can also be used.

[0055] A 3D weave structure defines how the warp and weft yarns interlace and vice versa, following an elementary pattern for each plane of the weave. The weave pattern is defined on a plurality of warp cross-section planes, also called warp planes, which show the path of the warp yarns relative to the weft yarns (represented in cross-section) within the thickness of a fibrous texture for a given column of warp yarns—that is, the path of one warp yarn for each layer of warp yarns—as well as on a plurality of weft cross-section planes, also called weft planes, which show the path of the weft yarns relative to the warp yarns (represented in cross-section) within the thickness of a fibrous texture for a given column of weft yarns—that is, the path of one weft yarn for each layer of weft yarns.The warp and weft cross-section plans are repeated in order throughout the weaving of the fibrous texture.

[0056] Figures 2 and 3 represent two successive warp-section planes of a 3D weave structure of fibrous texture 10, the representative pattern of which is defined on several parallel warp planes 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 Ti, T2, T3, T4, Ts, Te, T7, and Ts arranged in a staggered pattern. The FTR weft yarns of the weft yarn layers T1 to Ts are juxtaposed on several columns of weft yarns CT1 to CT? within the thickness of the fibrous texture.

[0057] 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, alternating 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, ensures that all yarns are interlaced throughout the entire elementary representative volume. Thus, there is no crack propagation path that is not blocked by a reinforcing yarn.

[0058] Figures 2 and 3 show the interlacing of FTR weft yarns by warp yarns 11, 21, 31, and 41 belonging to warp yarn layers C1 to C4, respectively. In the weave plane of Figure 2, a warp yarn 11 belonging to warp yarn layer C1 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 Figure 3, a warp yarn 11 belonging to warp yarn layer C1 links together FTR weft yarns belonging to three weft yarn layers with an offset of the linked weft yarn layers within the thickness of the fibrous texture (half-weft yarn layers T1 to T3). The same is true for warp yarns 21, 31, and 41 belonging to warp yarn layers C2, C3, and C4, respectively.

[0059] The weave structure is preferably defined so that each warp yarn (FCH) connects three layers of weft yarns. A known 3D weave structure that allows such connection is the layer-by-layer weave known as "interlock." "Interlock" weave refers to a weave structure in which each layer of warp yarns connects several layers of weft yarns, with all yarns in the same warp column having the same movement within the plane of the weave, and vice versa.

[0060] According to the present invention, the width of each warp yarn column is determined to achieve 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 linked to greater tear resistance, which is itself correlated with impact resistance.

[0061] The density in the warp yarn columns is maximized when the warp yarns have a compacted cross-section that matches the width of the warp column. However, this warp density must be optimized because if the width of the uncompacted warp yarn or strand exceeds the spacing allocated to the warp column in 3D weaving, weaving will be impossible due to warp yarn congestion in the loom and yarn-on-yarn friction during heddle movements for shear opening.

[0062] 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 fraction of a twisted yarn naturally increases with the flattening of its cross-section.

[0063] As illustrated in Figure 6, each warp yarn or strand (FCH) consists of a plurality of filaments (f), for example, carbon fibers, and in its free state—that is, 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%.

[0064] Figure 7 represents the FCH warp yarn from Figure 6 after compaction of the fibrous texture. After compaction, the FCH warp yarn, at a constant perimeter, has an elliptical shape where the largest dimension 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 roughly elliptical shape, the filaments f actually have a more circular shape within the warp yarn, which itself does indeed have an elliptical shape.

[0065] Figures 4 and 5 show a weft cross-section of the 3D weave structure of the fibrous texture 10, respectively before and after compaction of the fibrous texture. In the example described here, the fibrous structure 10 comprises three substantially extending layers of weft yarns Ti, T2, and T3, and four layers of warp yarns distributed into eight staggered half-layers of warp yarns Ci, C2, C3, C4, Cs, Ce, C7, and Cs. The warp yarns FCH of the warp yarn layers Ci to Cs are juxtaposed on several columns of warp yarns Cci to Ce? within the thickness of the fibrous texture, each warp yarn column having an ICCH width corresponding to the spacing allocated to each warp yarn column in the 3D weave.

[0066] In Figure 4, it can be seen that the FCH warp yarns, before compaction of the fibrous texture 10, have a circular shape, as described previously in relation to Figure 6. In their free or uncompacted state, the FCH warp yarns do not optimally occupy the ICCH width of each warp yarn column. However, as illustrated in Figure 5, these same FCH warp yarns, after compaction of the fibrous texture 10, have an elliptical shape that optimally occupies the ICCH width of each warp yarn column, in that the warp yarns extend almost across the entire ICCH width of each warp yarn column. In Figure 5, the FCH warp yarns 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 together, even in contact. Each warp yarn column thus exhibits a high warp density, both along its width and height.

[0067] This results in an optimal warp density after compaction (figure 5) without risk of congestion of the warp yarns in the loom (figure 4).

[0068] We now explain how the width of each column of warp threads is calculated in accordance with the invention.

[0069] The cross-sectional area of ​​a warp wire S t is calculated using the formula

[0070] D 2 next: S t = n — with D corresponding to the diameter of the warp thread. The sum S fThe cross-sectional areas of the filaments present in a warp thread d are calculated using the following formula: 2 S f = kn— with k corresponding to the number in thousands of filaments per warp thread and d corresponding to the diameter of a filament.

[0071] In their free state, that is, before compaction, the warp yarns have a circular cross-section and an initial intra-yarn fiber volume fraction (TVFi). The intra-yarn fiber volume fraction corresponds to the volume of fibers constituting the yarn divided by the total volume of said yarn, i.e.: TVFi = - s df- with:

[0072] • S f corresponding to the sum of the cross-sectional areas of the filaments present in a warp thread,

[0073] • S t corresponding to the air of a warp thread in its free state.

[0074] The perimeter p tThe circular cross-section of a free-running warp wire is calculated according to the formula p t = D, where D corresponds to the diameter of the warp thread. By

[0075] Consequently, if 2 S t = n — , as seen above, then p t

[0076] 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 ratio naturally increases with the compaction and ovalization of the warp yarn cross-section. For a given compaction ratio of the fibrous texture, there is a target fiber volume ratio (TVFc) for the warp yarns.

[0077] The perimeter p c the cross-section of the warp threads in the compacted state corresponds to that of an ellipse which can be calculated as follows: major axis of the ellipse and b: minor axis of the ellipse. Area S cThe cross-sectional area of ​​a warp wire in its compacted state, i.e., having an elliptical cross-section, is calculated using the following formula:

[0078] S c = nab

[0079] Thus, the TVFc target fiber volume fraction of the warp yarns in the compacted state can be expressed as follows:

[0080] S f _ kd 2

[0081] TVFc =

[0082] S c 4ab with:

[0083] S f corresponding to the sum of the cross-sectional areas of the filaments present in a warp thread,

[0084] S c 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. kd

[0085] If 2 TVFc

[0086] 4ab kd then 2 ab

[0087] 4TVFC kd and 2 b

[0088] 4aTVFc

[0089] The perimeter p t of the cross-section of the warp threads in their free state, i.e., uncompacted, and the perimeter p c Since the cross-section of the warp threads in the compacted state is equivalent due to the twisting of the warp threads, we obtain the following formula: kd with = - 2 aTVFc, we obtain: which is equivalent to: which is equivalent to the following trinomial:

[0090] By setting x=a 2 The discriminant of the above trinomial is:

[0091] If A > 0:

[0092] We then obtain the following formula (1):

[0093] 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 TVFi 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.

[0094] Therefore, for given TVFi and TVFc fiber volumetric ratios, it is possible to calculate an optimal warp yarn column width because it is directly related to the cross-sectional width of the warp yarns in the compacted state. According to the invention, the width of each warp yarn column in the fibrous texture is between 1.8 times and 2.2 times the value a, which corresponds to -10% of 2a and +10% of 2a, respectively.

[0095] Figures 9 to 14 are curves which show the evolution of the value 2a of a yarn or strand, that is to say the variation of the width of the major axis a of the ellipse (figure 7), obtained with formula (1), namely as a function of the volumetric rate of TVFi fibers of the warp yarns in the free state and the volumetric rate of TVFc fibers of the same warp yarns in the compacted state of its intra-yarn or intra-strand fiber volumetric rate for yarns or strands having a title of respectively 12k (figure 9), 24k (figure 10), 36k (figure 11), 48k (figure 12), 72k (figure 13) and 96k (figure 14). The count or density of a yarn or strand corresponds to its thickness (depending on the type of yarn, the density varies, therefore 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 count is expressed in "k", which corresponds to the number of filaments per strand in thousands.For example, a 12k wire contains 12000 filaments, a 24k wire contains 24000 filaments, a 48k wire contains 48000 filaments, etc. Each of Figures 9 to 14 includes three curves corresponding to an initial or free-state TVFi fiber volume ratio of 40%, 50% and 60% respectively.

[0096] 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.

[0097] According to the curves in Figures 9 to 14, we can see, for example, that for an initial TVFi fiber volume ratio of 50% and a target TVFc fiber volume ratio between 70% and 80%, the optimized ICCH width for the channel columns is between:

[0098] - between 0.9 mm and 1.1 mm with 2ct=1 for wires or strands with a fineness of 12k,

[0099] - between 1.35 mm and 1.65 mm with 2a=1.5 for wires or strands with a fineness of 24k,

[0100] - between 1.66 mm and 2 mm with 2 ct=1.84 for wires or strands with a fineness of 36k,

[0101] - between 1.9 mm and 2.3 mm with 2a=2.13 for wires or strands with a fineness of 48k, - between 2.34 mm and 2.9 mm with 2a=2.61 for wires or strands with a fineness of 72k,

[0102] - between 2.7 mm and 3.3 with 2a=3 for wires or strands with a fineness of 96k.

[0103] According to another example, the value 2a of a yarn or strand corresponding to the width of 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 ICCH width optimized for warp columns is:

[0104] - between 0.74 mm and 1.1 mm with 2a=0.9 for wires or strands with a fineness of 12k,

[0105] - between 1 mm and 1.28 mm with 2a=1.16 for wires or strands with a fineness of 24k,

[0106] - between 1.28 mm and 1.56 mm with 2a=1.42 for wires or strands with a fineness of 36k,

[0107] - between 1.48 mm and 1.8 mm with 2a=1.64 for wires or strands with a fineness of 48k,

[0108] - between 1.8 mm and 2.21 mm with 2a=2.01 mm for wires or strands with a fineness of 72k,

[0109] - between 2.1 mm and 3.3 with 2a=2.55 for wires or strands with a fineness of 96k.

[0110] According to another example, the value 2a of a yarn or strand corresponding to the width of the major axis a of the ellipse (Figure 7) was calculated using formula (1) for Torayca® T1100 carbon yarns or strands (marketed by Toray) whose individual filaments have an average diameter of 5.5 µm. 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 ICCH width optimized for warp columns is:

[0111] - between 0.98 mm and 1.2 mm with 2a=1.09 for wires or strands with a fineness of 12k,

[0112] - between 1.4 mm and 1.7 mm with 2a=1.55 for wires or strands with a fineness of 24k,

[0113] - between 1.7 mm and 2.1 mm with 2a=1.89 for wires or strands with a fineness of 36k,

[0114] - between 2 mm and 2.4 mm with 2a=2.19 for wires or strands with a fineness of 48k,

[0115] - between 2.4 mm and 2.94 with 2a=2.68 for wires or strands with a fineness of 72k, - between 2.78 mm and 3.3 with 2a=3.4 for wires or strands with a fineness of 96k.

[0116] 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 individual 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 ICCH width optimized for the chain columns is:

[0117] - between 0.95 mm and 1.17 mm with 2a=1.06 for wires or strands with a 4k fineness,

[0118] - between 1.35 mm and 1.65 mm with 2a=1.5 for wires or strands with a fineness of 8k,

[0119] - between 1.66 mm and 2.02 mm with 2a=1.84 for wires or strands with a fineness of 12k,

[0120] - between 1.9 mm and 2.53 mm with 2a=2.13 for wires or strands with a fineness of 16k,

[0121] - between 2.34 mm and 2.86 mm with 2a=2.60 mm for wires or strands with a fineness of 24k,

[0122] - between 2.71 mm and 3.3 with 2a=3.31 for wires or strands with a fineness of 32k.

[0123] The control of the width of the warp columns is carried out in a jacquard type loom such as loom 10 in Figure 1 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.

[0124] As is known, the loom 10 is equipped with a Jacquard mechanism 11 supported by a superstructure not shown in Figure 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.

[0125] Each heddle 22 includes an eyelet 23 through which a warp thread FCH passes. The heddles 22 and their associated eyelet 23 are set in motion in a substantially vertical oscillating motion 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 certain warp threads FCH to be lifted and thus create a shovel 15 allowing the introduction of weft threads FTR.

[0126] 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.

[0127] 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 column of warp yarns in the fabric to be produced. More precisely, when we want to weave with a specific ICCH width 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 ICCH width determined as shown in Figure 1 for the warp yarn columns CC1 and CC2, which is then reflected in the woven fibrous texture (Figure 4). For example, if we want to obtain a woven fibrous texture with ten layers of warp yarns with warp yarn columns having an ICCH width of 2 mm, we adjust the distance d2i 1 between the columns 211 of the holes 210 of the stacking board 21 to 2 mm.

[0128] 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 within 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 within the fibrous texture is called the "waviness angle" (Figures 2 and 3). The waviness angle is a parameter that is primarily determined by the weaving conditions defined in the loom.

[0129] 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 multiple layers of weft yarns and, consequently, to obtain a monolithic material without a preferred crack propagation path. Figure 8 is a curve showing the results of stiffness calculations as a function of the warp angle. The calculations were performed using measurements taken on a plate-type specimen made of CMO composite material with unidirectional (UD) fiber reinforcement, i.e., without warp. 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 drawing an analogy between the angle of embouchure and a disorientation in the plane, which is reflected in the curve in Figure 8. We thus observe a significant drop in stiffness when the angle of embouchure exceeds 10°.

[0130] 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°.

[0131] Therefore, by using a 3D weave structure allowing the interlacing or bonding of several layers of weft yarns with a warp yarn angle between 1° and 10°, an optimized compromise between impact resistance and stiffness is defined.

[0132] 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 rate of fibers in the fibrous reinforcement of the final part in composite material.

[0133] The manufacture of a part in composite material therefore includes at least the compaction of the fibrous texture, the shaping of the latter (which can be carried out at the same time as the compaction) and the densification of the fibrous preform thus obtained.

[0134] 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.

[0135] This densification can be achieved, using a known method, via the liquid-based material mixing (LBM) process. The liquid-based process involves 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.

[0136] 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.

[0137] 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. In 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 internal space between the point where the resin is injected and the resin discharge ports in order to control and optimize the impregnation of the preform by the resin.

[0138] The resin used can be, for example, an epoxy resin with a temperature class of 180 °C (the 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 will be subjected. Once the resin has been injected throughout the reinforcement, it is cured by heat treatment according to the RTM process.

[0139] After injection and polymerization, the part is demolded. Finally, the part can be trimmed to remove excess resin and the chamfers are machined.

[0140] Other known densification and / or matrix precursor processes can also be used to manufacture the part from composite material.

[0141] 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 (Ci-Cs) 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 (Ti-Ts) juxtaposed over several columns of weft yarns or strands (CT1-CT7) in the thickness of the fibrous texture (30), 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 (ICCH) of each column of warp yarns or strands (CCi-CC7) is between 1.8 times and 2.2 times a value a, the value a being calculated from the following formula : with d: diameter of the filaments of the warp threads or strands TVFc: Target fiber volume percentage of warp yarns or strands.

2. Fibrous texture according to claim 1, wherein the warp yarns or strands (WH) of the warp yarn or strand layers (Ci-Cs) 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 warp yarn layer (C1-C4) 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 (WH) and the weft yarns or strands (WTR) 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 (ICCH) of each column of warp yarns or strands (CC1-CC7) is included: - 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.

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 (Ci-Cs) 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 (T1-Ts) placed side by side over several columns of weft yarns or strands (CT1-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 (ICCH) 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: with d: diameter of the filaments of the warp threads or strands TVFc: Target fiber ratio of warp wires or strands

10. A method according to claim 9, wherein the warp yarns or strands (WH) of the warp yarn or strand layers (Ci-Cs) have a swaging angle (a) between 1° and 10°.

11. A method according to claim 9 or 10, wherein warp yarns (WH) 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 (WTR).

12. A method according to any one of claims 8 to 11, in which the warp yarns or strands (WH) and the weft yarns or strands (WTR) are made of carbon fiber filaments of glass, aramid or PBO Zylon®.

13. A method according to any one of claims 8 to 12, wherein the carbon filaments have a cross-sectional diameter between 5 pm and 5.4 pm and wherein the width (ICCH) of each column of warp wires or strands (CC1-CC7) is included: - 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.

Images