Fibrous blank with an armor suitable for removing an area

Abstract

The invention relates to a fiber blank (5) produced by three-dimensional weaving, the fiber blank (5) comprising a first skin (211) and a second skin (212) situated on either side of a core portion (220), the fiber blank (5) further comprising at least one intermediate portion (230) located between the core portion (220) and the first skin (211), the core portion (220) being intended to form part of the fibrous reinforcement of the final composite material part (5000) and at least one intermediate portion (230) being intended to be removed, at least in part, to obtain the fibrous reinforcement of the final composite material part (5000), the fiber blank (5) being characterized in that the warp / weft ratio of the core portion (220) is greater than the warp / weft ratio of the at least one intermediate portion (230). Figure for the abridged version: Fig. 1

Description

Title of the invention: Fibrous blank with an adapted reinforcement for the removal of a zone. Technical field

[0001] The present invention relates to a fibrous blank intended to form the fibrous reinforcement of a part made of composite material, for example a turbomachine part such as a blade. Previous technique

[0002] In order to obtain lightweight turbomachine parts with excellent thermomechanical properties, parts are manufactured using a well-known method of composite material, i.e., parts comprising a fibrous reinforcement densified by a matrix. The use of composite materials helps to optimize turbomachine performance, particularly by reducing the overall mass of the turbomachine, which contributes to lower fuel consumption and therefore a significant reduction in pollutant emissions.

[0003] Furthermore, ceramic matrix composite materials withstand temperatures ranging from 600°C to 1400°C. Due to their superior resistance to high temperatures, ceramic matrix composite materials require less cooling. Since this cooling is traditionally obtained from the compressor, which impacts the turbomachine's efficiency, composite materials allow for even greater engine efficiency improvements and reduced fuel consumption.

[0004] In particular, it is known to produce the fibrous blank of the part by three-dimensional weaving of a plurality of warp yarns with a plurality of weft yarns on a jacquard-type loom. The fibrous blank is then densified by a matrix to obtain a raw composite material part which will then be machined.

[0005] In order to produce parts with variations in thickness, it is known to vary the warp / weft ratio in the core portion of the fiber blank. For example, in order to locally increase the thickness of the fiber blank, it is known to double the number of weft yarns in the core portion of the fiber blank.

[0006] However, it has been observed that composite material parts obtained from such fibrous blanks may exhibit suboptimal mechanical performance. Description of the invention

[0007] The main purpose of the present invention is to provide a fibrous blank that improves the mechanical performance of the final composite material part.

[0008] The inventors deserve credit for observing that the suboptimal mechanical performance was caused by using an unbalanced warp / weft ratio in the core portion while maintaining a balanced warp / weft ratio in the outer portions. Indeed, during the machining of the final composite part, it is primarily the outer portions that are removed, while the core portion is retained. Thus, the portions with an unbalanced warp / weft ratio, and therefore exhibiting weaker mechanical properties, were retained in the final part, whereas the portions with a balanced and high warp / weft ratio, and therefore exhibiting the best mechanical properties, were at least partially removed from the final part. Furthermore, a balanced and high warp / weft ratio imparts less flexibility to the fiber blank than an unbalanced warp / weft ratio.Thus, the fibrous blanks of the prior art, exhibiting a balanced and significant warp / weft ratio in their outer layers, are not very flexible. Consequently, they are difficult to shape and place in an impregnation or injection mold without crushing the fibers. Difficulties in shaping or densification, as well as crushing problems, cause mechanical defects in the final part.

[0009] By identifying these problems, the invention proposes a fibrous blank intended to provide at least part of the fibrous reinforcement of a part made of composite material, the fibrous blank being made in one piece by three-dimensional weaving between a plurality of warp yarns extending along a longitudinal direction and a plurality of weft yarns extending along a transverse direction, the fibrous blank comprising a first skin and a second skin located on either side of a core portion along a thickness direction perpendicular to the longitudinal and transverse directions, the fibrous blank further comprising at least one intermediate portion present between the core portion and the first skin along the thickness direction, the fibrous blank being characterized in that the warp / weft ratio of the core portion is greater than the warp / weft ratio of the at least one intermediate portion.

[0010] The warp / weft ratio corresponds to the ratio between the volume occupied by the warp yarns and the volume occupied by the weft yarns.

[0011] The core portion is intended to be part of the fibrous reinforcement of the composite material part and at least an intermediate portion is intended to be removed at least in part to obtain the fibrous reinforcement of the composite material part.

[0012] Thus, the portions of the fiber blank exhibiting a low and unbalanced warp / weft ratio are located at the periphery of the fiber blank to be machined, rather than at the center of the fiber blank retained in the final part. Consequently, the mechanical performance of the final part is improved because it primarily exhibits a balanced warp / weft ratio. Furthermore, such a fiber blank is easier to impregnate with a fluid or to infiltrate via gas to form the matrix, which further enhances the mechanical characteristics of the final part.

[0013] Portions with a low and unbalanced warp / weft ratio are more flexible than portions with a high and balanced warp / weft ratio. Thus, by placing the intermediate portions at the periphery of the fiber blank, the overall fiber blank is made more flexible. The fiber blank can therefore be shaped more easily and with less crushing. In particular, the placement of the fiber blank in the mold is facilitated, and it can properly fill the mold. Consequently, the mechanical properties of the final composite part are excellent.

[0014] According to a particular aspect of the invention, the warp / weft ratio of the core portion is between 0.9 and 1.1.

[0015] Thus, the heart portion has a very balanced warp / weft ratio, which allows it to exhibit better mechanical characteristics.

[0016] According to a particular aspect of the invention, the warp yarns of at least an intermediate portion separate the weft yarns into groups of at least two weft yarns in each warp yarn plane perpendicular to the transverse direction.

[0017] Thus, a lower warp / weft ratio in the intermediate portion compared to the core portion is achieved by increasing the number of weft yarn insertions in the intermediate portion. In particular, the number of weft yarns in the intermediate portion can be doubled or tripled. This results in a greater number of weft yarns crossing each warp yarn plane perpendicular to the transverse direction without increasing the number of warp yarns in said warp yarn planes.

[0018] In particular, the number of warp yarn planes perpendicular to the transverse direction in at least one intermediate portion is greater than the number of warp yarn planes perpendicular to the transverse direction in the core portion.

[0019] Thus, to compensate for the increase in the number of weft yarns crossing each warp yarn plane perpendicular to the transverse direction, the number of warp yarn planes perpendicular to the transverse direction is increased. The yarns Additional weft threads thus remain properly held in place by the warp threads, with a much lower risk of slippage.

[0020] In other words, the warp yarn layers of the fibrous blank extending perpendicularly to the thickness direction comprise more warp yarns when they belong to the intermediate portion than when they belong to the core portion.

[0021] According to a particular aspect of the invention, the second skin is intended to form the fibrous reinforcement of the intrados surface of a blade or a blade.

[0022] According to a first embodiment of the invention, the core portion is adjacent to the second skin along the thickness direction and the intermediate portion is adjacent to the first skin along the thickness direction.

[0023] According to a second embodiment of the invention, the fibrous blank comprises a first intermediate portion adjacent to the first skin along the thickness direction and a second intermediate portion adjacent to the second skin along the thickness direction.

[0024] According to a particular aspect of the invention, the weave structure of the core portion and of the intermediate portion(s) is of the interlock type.

[0025] According to a particular aspect of the invention, the fibrous blank comprises at least a first part and a second part along the longitudinal direction, the first part being devoid of intermediate portions so that the first part of the fibrous blank is less thick than the second part of the fibrous blank along the thickness direction.

[0026] The invention relates to a fibrous blank intended to provide at least part of the fibrous reinforcement of a part made of composite material, the fibrous blank being made in one piece by three-dimensional weaving between a plurality of warp yarns extending along a longitudinal direction and a plurality of weft yarns extending along a transverse direction, the fibrous blank comprising a first skin and a second skin located on either side of a core portion along a thickness direction perpendicular to the longitudinal and transverse directions, the fibrous blank further comprising at least one intermediate portion present between the core portion and the first skin along the thickness direction,the core portion being intended to form part of the fibrous reinforcement of the composite material part and at least an intermediate portion being intended to be removed at least partially to obtain the fibrous reinforcement of the composite material part, the fibrous blank being characterized in that the warp / weft ratio of the core portion is closer to 1 than the warp / weft ratio of the at least an intermediate portion.

[0027] Thus, the portion of the heartwood that remains in the final part has a more balanced warp / weft ratio than the intermediate portion(s). Therefore, the mechanical characteristics of the final part will be improved.

[0028] According to a particular aspect of the invention, the average count of the weft yarns in the core portion corresponds to between 90% and 110% of the average count of the weft yarns in the intermediate portion(s).

[0029] Thus, the difference in warp / weft ratio between the core portion and the intermediate portion(s) can be achieved by using weft yarns of the same count in the core portion and in the intermediate portion(s). The weaving of the fiber blank can therefore be carried out using the same type of weft yarns, thus avoiding bobbin changes on the loom.

[0030] According to a particular aspect of the invention, the average count of the weft yarns in the intermediate portion(s) is greater than the average count of the weft yarns in the core portion. In particular, the average count of the weft yarns in the intermediate portion(s) is more than 110% of the average count of the weft yarns in the core portion.

[0031] Thus, the difference in warp / weft ratio between the core portion and the intermediate portion(s) can be achieved without resorting to doubling or tripling weft yarns.

[0032] The invention also proposes a method for manufacturing a part made of composite material comprising:

[0033] - the production of a fibrous blank as described above,

[0034] - the arrangement of the fibrous blank in a mold, then

[0035] - the densification of the fibrous blank by a matrix so as to obtain a raw composite material part comprising a core portion whose fibrous reinforcement is formed by the core portion of the fibrous blank, at least one intermediate portion whose fibrous reinforcement is formed by at least one intermediate portion of the fibrous blank, and a first skin and a second skin whose fibrous reinforcement is formed respectively by the first skin and the second skin of the fibrous blank,

[0036] - the removal of at least one area of ​​the raw part made of composite material, said area including at least part of the at least an intermediate portion and at least part of the first skin.

[0037] According to a particular aspect of the invention, the resulting composite material part has a ceramic matrix.

[0038] According to a particular aspect of the invention, the resulting composite material part has an organic matrix. Brief description of the drawings

[0039] [Fig-1] The [Fig. 1] is a partial weaving plan of an example of a fibrous blank according to the first embodiment of the invention.

[0040] [Fig.2] The [Fig.2] is a partial schematic view of an example of a fibrous blank according to the second embodiment of the invention.

[0041] [Fig.3] The [Fig.3] is a partial schematic view of a fibrous preform arranged in a mold obtained by shaping the fibrous blank of the [Fig.1].

[0042] [Fig.4] The [Fig.4] is a partial schematic view of a raw part in composite material obtained by densification by a matrix of the fibrous preform of the [Fig.3].

[0043] [Fig.5] The [Fig.5] is a partial schematic view of a final part made of composite material obtained by removing an area of ​​the raw part of the [Fig.4].

[0044] [Fig.6] The [Fig.6] is a partial schematic view of a final part in composite material obtained by removing an area from a rough part in composite material obtained by densification of the fibrous blank of the [Fig.2]. Description of the implementation methods

[0045] The present invention relates in particular to a fibrous blank which is shaped to obtain a fibrous preform. The fibrous preform is then densified by a matrix to obtain a rough part made of composite material. One or more areas of the rough part made of composite material are then removed to obtain a final part made of composite material.

[0046] Figures 1 and 2 each illustrate an example of a fibrous blank 5, 6 according to the invention.

[0047] The fibrous blank 5, 6 is produced in a single piece by three-dimensional weaving between a plurality of layers of warp yarns 51 and a plurality of layers of weft yarns 52. "Three-dimensional weaving" here refers to a weaving method in which at least some of the warp yarns interlace weft yarns over several warp layers. A fibrous blank or preform produced by three-dimensional weaving is considered to include another type of weaving on its surface, for example, two-dimensional weaving, in order to improve its surface finish.

[0048] The fibrous blank 5, 6 is preferably produced using a Jacquard-type loom. Such a loom is described, for example, in document FR 3 074 195 AL

[0049] The warp yarns 51 extend generally along a longitudinal direction DL. The weft yarns 52 extend generally along a transverse direction DT. The longitudinal direction DL is perpendicular to the transverse direction DT. The blank fibrous 5, 6 extends in thickness along a thickness direction DE perpendicular to the longitudinal direction DL and transverse direction DT.

[0050] The warp yarn layers 51 extend perpendicularly to the thickness direction DE. The weft yarn layers 52 extend perpendicularly to the thickness direction DE. The fibrous blank 5, 6 has warp yarn planes 51 perpendicular to the transverse direction DT. Such planes perpendicular to the transverse direction DT can also be called "weave planes".

[0051] Figure 1 illustrates a partial view of a fibrous blank 5 according to a first embodiment of the invention. In particular, Figure 1 illustrates a warp yarn plane 51 perpendicular to the transverse direction DT.

[0052] The fibrous blank 5 comprises at least one portion 200 including a first skin 211 and a second skin 212. The first skin 211 and the second skin 212 delimit the fibrous blank 5 along the thickness direction DE. Conventionally, the first skin 211 and the second skin 212 can each be formed by a layer of weft yarns woven with a layer of warp yarns. The skins 211, 212 can have a type of weave suitable for an external surface. Thus, the skins 211, 212 can, for example, have a two-dimensional weave or a satin weave.

[0053] Part 200 further includes a core portion 220 located between the first skin 211 and the second skin 212 along the thickness direction DE. The core portion 220 is directly adjacent to the second skin 212 along the thickness direction DE. The core portion 220 is intended to form part of the fibrous reinforcement of the final part. Thus, the weave structure of the core portion 220 is adapted for structural functions. The weave structure of the core portion 220 makes it possible to impart desirable mechanical properties to the final part.

[0054] In order to improve the mechanical characteristics of the core portion 220, it preferably has a warp / weft ratio close to 1. Thus, the warp / weft ratio of the core portion 220 can be between 0.9 and 1.1.

[0055] The core portion 220 preferably has an interlock weave, that is, a type of three-dimensional weave in which each layer of warp yarns interlocks several layers of weft yarns, with all the yarns in the same warp column having the same movement in the plane of the weave. Other types of three-dimensional weaves are possible, such as, for example, multi-plain or multi-satin weaves. Various types of three-dimensional weaves that can be used to form the fiber blank are described in document WO 2006 / 136755.

[0056] The core portion 220 may comprise at least four layers of warp yarns and at least four layers of weft yarns.

[0057] The part 200 further comprises an intermediate portion 230 located between the core portion 220 and the first skin 211 along the thickness direction DE. The intermediate portion 230 is directly adjacent to the first skin 211 along the thickness direction DE. The intermediate portion 230 is directly adjacent to the core portion 220 along the thickness direction DE. The intermediate portion 230 is intended to be at least partially removed to obtain the final part. The intermediate portion 230 may be entirely absent from the final part.

[0058] The intermediate portion 230 is conventionally used to increase the bulk of the fiber blank 5. Thus, the intermediate portion 230 can increase the thickness of the fiber blank 5 along the thickness direction DE. Consequently, the warp / weft ratio of the intermediate portion 230 is lower than the warp / weft ratio of the core portion 220. Preferably, the intermediate portion 230 has a warp / weft ratio far from 1. In particular, the warp / weft ratio of the intermediate portion 230 is further from 1 than the warp / weft ratio of the core portion 220. The warp / weft ratio of the intermediate portion 230 can be less than 0.6.

[0059] The lower warp / weft ratio in the intermediate portion can be obtained in several ways.

[0060] The intermediate portion 230 can conventionally include additional weft thread insertions 52. Thus, the warp threads 51 of the intermediate portion 230 can separate the weft threads 52 into groups of at least two weft threads 52 in each warp thread plane 51 perpendicular to the transverse direction Dt, as illustrated in [Fig. 1]. If the groups comprise exactly two weft threads 52, this results in a doubling of the weft threads 52. If the groups comprise exactly three weft threads, this results in a tripling of the weft threads. In other words, a doubling, or respectively a tripling, of the weft threads corresponds to a weave in which the weft threads are bound in groups of two, or respectively in groups of three.

[0061] In the case of additional insertions of weft yarns 52, it is preferable to increase the number of warp yarn planes 51 perpendicular to the transverse direction Dt in the intermediate portion 230, in order to maintain strong binding of the weft yarns 52. This greatly reduces the risk of slippage of the weft yarns 52 in the weave. In other words, the warp yarn layers 51 of the fiber blank 5 contain more warp yarns 51 when they belong to the intermediate portion 230 than when they belong to the core portion 220. Thus, the number of warp yarns 51 in each warp yarn layer 51 perpendicular to the thickness direction DE belonging to the intermediate portion 230 is greater than number of warp wires 51 in each layer of warp wires 51 perpendicular to the thickness direction DE belonging to the core portion 220, for the same position along the longitudinal direction DL.

[0062] It is also possible to use weft yarns with a higher count to reduce the warp / weft ratio. Thus, the average count of the weft yarns in the middle portion can be higher than the average count of the weft yarns in the core portion. The middle portion can conventionally have the same weave as the core portion with a doubling of the weft yarns or with weft yarns of a higher count.

[0063] The intermediate portion 230 preferably has the same type of weave as the core portion 220 in order to improve the mechanical characteristics of the interface between the core portion 220 and the intermediate portion 230. The intermediate portion 230 preferably has an interlock weave. Other types of three-dimensional weaves are possible, such as, for example, multi-weave or multi-satin weaves.

[0064] The intermediate portion 230 may comprise at least three layers of warp yarns.

[0065] The fibrous blank according to the first embodiment can be formed solely by the portion 200. However, the fibrous blank 5 according to the first embodiment of the invention can comprise several portions 100, 200 along the longitudinal direction DL. In particular, the fibrous blank 5 can comprise several portions such as the portion 200 described above along the longitudinal direction DL. Portions such as the portion 200 described above can locally increase the bulk and thickness of the fibrous blank. These several portions 200 can be adjacent to each other or separated by other portions different from the portion 200 described above.

[0066] The fibrous blank 5 can have a constant number of warp threads along the longitudinal direction DL. Thus, all parts 100, 200 of the fibrous blank 5 can have the same number of warp threads 51.

[0067] In the example illustrated in [Fig. 1], the fibrous blank 5 comprises a first portion 100 and a second portion 200 along the longitudinal direction DL. The second portion corresponds to the portion 200 described previously. The first portion 100 and the second portion 200 comprise the same number of warp threads 51. The first portion 100 can be directly adjacent to the second portion 200 along the longitudinal direction DL.

[0068] The first part 100 comprises a first skin 111 and a second skin 112. The first skin 111 and the second skin 112 delimit the following fibrous blank 5 The thickness direction DE. The first skin 111 of the first part 100 can be an extension of the first skin 211 of the second part 200. The second skin 112 of the first part 100 can be an extension of the second skin 212 of the second part 200. Conventionally, the first skin 111 and the second skin 112 can each be formed by a layer of weft yarns woven with a layer of warp yarns. Skins 111 and 112 can have a type of weave suitable for an exterior surface. Thus, skins 111 and 112 can, for example, have a two-dimensional weave or a satin weave.

[0069] The first part 100 further comprises a core portion 120 situated between the first skin 111 and the second skin 112 along the thickness direction DE. The core portion 120 of the first part 100 is directly adjacent to the first skin 111 and the second skin 112 along the thickness direction DE. The core portion 120 of the first part 100 may be directly adjacent to the core portion 220 of the second part 200 along the longitudinal direction DL. The core portion 120 of the first part 100 is intended to form at least a partial part of the fibrous reinforcement of the final piece. Thus, the weave structure of the core portion 120 is suitable for structural functions. The weave structure of the core portion 120 makes it possible to impart desirable mechanical properties to the final piece.

[0070] In order to improve the mechanical characteristics of the core portion 120, it preferably has a warp / weft ratio close to 1. Preferably, the warp / weft ratio of the core portion 120 of the first part 100 is similar to the warp / weft ratio of the core portion 220 of the second part 200. Thus, the warp / weft ratio of the core portion 120 can be between 0.9 and 1.1.

[0071] The core portion 120 of the first part 100 preferably has the same type of weave as the core portion 220 of the second part 200, in order to improve the mechanical characteristics of the junction between the first part 100 and the second part 200. The core portion 120 of the first part 100 may have all the weaves or all the types of weaves described previously for the core portion 220 of the part 200. The core portion 120 of the first part 100 may comprise at least four layers of warp yarns and at least four layers of weft yarns.

[0072] Figure [Fig. 2] illustrates a partial view of a fibrous blank 6 according to a second embodiment of the invention.

[0073] The fibrous blank 6 comprises at least one portion 400 including a first skin 411 and a second skin 412. The first skin 411 and the second skin 412 delimit the fibrous blank 6 along the thickness direction DE. Conventionally, the first skin 411 and the second skin 412 can each be formed by a layer of weft yarns woven with a layer of warp yarns. The hides 411, 412 may have a type of weave suitable for an exterior surface. Thus, hides 411, 412 may, for example, have a two-dimensional weave or a satin weave.

[0074] Part 400 further includes a core portion 420 located between the first skin 411 and the second skin 412 along the thickness direction DE. The core portion 420 is intended to form part of the fibrous reinforcement of the final part. Thus, the weave structure of the core portion 420 is adapted to structural functions. The weave structure of the core portion 420 makes it possible to impart desirable mechanical properties to the final part.

[0075] In order to improve the mechanical characteristics of the core portion 420, it preferably has a warp / weft ratio close to 1. Thus, the warp / weft ratio of the core portion 420 can be between 0.9 and 1.1.

[0076] The core portion 420 preferably has an interlock weave. Other types of three-dimensional weave are possible, such as, for example, multi-plain or multi-satin weaves. Various types of three-dimensional weave that can be used to form the fibrous blank are described in document WO 2006 / 136755.

[0077] The core portion 420 may comprise at least four layers of warp yarns and at least four layers of weft yarns.

[0078] The portion 400 further comprises a first intermediate portion 431 located between the core portion 420 and the first skin 411 along the thickness direction DE. The first intermediate portion 431 is directly adjacent to the first skin 411 along the thickness direction DE. The first intermediate portion 431 is directly adjacent to the core portion 420 along the thickness direction DE. The portion 400 also comprises a second intermediate portion 432 located between the core portion 420 and the second skin 412 along the thickness direction DE. The second intermediate portion 432 is directly adjacent to the second skin 412 along the thickness direction DE. The second intermediate portion 432 is directly adjacent to the core portion 420 along the thickness direction DE.

[0079] The intermediate portions 431 and 432 are intended to be removed at least partially to obtain the final part. The intermediate portions 431 and 432 may be intended to be entirely absent from the final part.

[0080] The intermediate portions 431 and 432 are conventionally used to increase the bulk of the fiber blank 5. Thus, the intermediate portions 431 and 432 can increase the thickness of the fiber blank 6 along the thickness direction DE. Consequently, the warp / weft ratio of the intermediate portions 431 and 432 is less than the warp / weft ratio of the core portion 420. Preferably, the intermediate portions 431 and 432 have a warp / weft ratio far from 1. In particular, the warp / weft ratio of the intermediate portions 431 and 432 is further from 1 than the warp / weft ratio of the core portion 420. The warp / weft ratio of the intermediate portions 431 and 432 may be less than 0.6.

[0081] The lower warp / weft ratio in the intermediate portions can be obtained in several ways.

[0082] The intermediate portions 431, 432 can conventionally include additional weft thread insertions. Thus, the warp threads of the intermediate portions 431, 432 can separate the weft threads into groups of at least two weft threads in each warp thread plane perpendicular to the transverse direction DT. If the groups comprise exactly two weft threads, this results in a doubling of the weft threads. If the groups comprise exactly three weft threads, this results in a tripling of the weft threads.

[0083] In the case of additional weft insertions, it is preferable to increase the number of warp yarn planes perpendicular to the transverse direction DT in the intermediate portions 431, 432, in order to maintain strong weft yarn binding. This significantly reduces the risk of weft yarn slippage in the weave. In other words, the warp yarn layers of the fiber blank 6 contain more warp yarns when they belong to one of the intermediate portions 431, 432 than when they belong to the core portion 420. Thus, the number of warp yarns in each warp yarn layer perpendicular to the thickness direction DE belonging to one of the intermediate portions 431, 432 is greater than the number of warp yarns in each warp yarn layer perpendicular to the thickness direction DE belonging to the core portion 420, for the same position along the longitudinal direction DL.

[0084] It is also possible to use weft yarns with a higher count to reduce the warp / weft ratio. Thus, the average count of the weft yarns in the intermediate sections can be higher than the average count of the weft yarns in the core section. The intermediate sections can conventionally have the same weave as the core section with a doubling of the weft yarns or with weft yarns of a higher count. The intermediate sections can conventionally have the same weave as the core section with a doubling of the weft yarns or with weft yarns of a higher count.

[0085] The intermediate portions 431 and 432 preferably have the same type of weave structure as the core portion 420 in order to improve the mechanical characteristics of the interface between the core portion 220 and the intermediate portions 431 and 432. The intermediate portions 431 and 432 preferably have an interlock weave. Other types of three-dimensional weave are possible, such as multi-plain or multi-satin weaves.

[0086] The intermediate portions 431 and 432 can each comprise at least three layers of warp yarns.

[0087] The fibrous blank according to the second embodiment can be formed solely by the portion 400. However, the fibrous blank 6 according to the second embodiment of the invention can comprise several portions 300, 400 along the longitudinal direction DL. In particular, the fibrous blank 6 can comprise several portions such as the portion 400 described above along the longitudinal direction DL. Portions such as the portion 400 described above can locally increase the bulk and thickness of the fibrous blank. These several portions 400 can be adjacent to each other or separated by other portions different from the portion 400 described above.

[0088] The fibrous blank 6 can have a constant number of warp threads along the longitudinal direction DL. Thus, all parts 300, 400 of the fibrous blank 6 can have the same number of warp threads.

[0089] In the example illustrated in [Fig. 2], the fibrous blank 6 comprises a first portion 300 and a second portion 400 along the longitudinal direction DL. The second portion corresponds to the portion 400 described previously. The first portion 300 and the second portion 400 comprise the same number of warp threads. The first portion 300 can be directly adjacent to the second portion 400 along the longitudinal direction DL.

[0090] The first part 300 comprises a first skin 311 and a second skin 312. The first skin 311 and the second skin 312 define the fibrous blank 6 along the thickness direction DE. The first skin 311 of the first part 300 may be an extension of the first skin 411 of the second part 400. The second skin 312 of the first part 300 may be an extension of the second skin 412 of the second part 400. Conventionally, the first skin 311 and the second skin 312 may each be formed by a layer of weft yarns woven with a layer of warp yarns. The skins 311 and 312 may have a type of weave suitable for an external surface. Thus, the skins 311 and 312 may, for example, have a two-dimensional weave or a satin weave.

[0091] The first part 300 further comprises a core portion 320 situated between the first skin 311 and the second skin 312 along the thickness direction DE. The core portion 320 of the first part 300 is directly adjacent to the first skin 311 and the second skin 312 along the thickness direction DE. The portion The core portion 320 of the first part 300 can be directly adjacent to the core portion 420 of the second part 400 along the longitudinal direction DL. The core portion 320 of the first part 300 is intended to form at least a portion of the fibrous reinforcement of the final part. Thus, the weave structure of the core portion 320 is suitable for structural functions. The weave structure of the core portion 320 allows the final part to possess desirable mechanical properties.

[0092] In order to improve the mechanical characteristics of the core portion 320, it preferably has a warp / weft ratio close to 1. Preferably, the warp / weft ratio of the core portion 320 of the first part 300 is similar to the warp / weft ratio of the core portion 420 of the second part 400. Thus, the warp / weft ratio of the core portion 320 can be between 0.9 and 1.1.

[0093] The core portion 320 of the first part 300 preferably has the same weave as the core portion 420 of the second part 400, in order to improve the mechanical characteristics of the junction between the first part 300 and the second part 400. The core portion 320 of the first part 300 may have all the weaves or all the types of weaves described previously for the core portion 420 of the part 400. The core portion 320 of the first part 300 may comprise at least four layers of warp yarns and at least four layers of weft yarns.

[0094] The fibrous blank 5, 6 can then be shaped to obtain a fibrous preform.

[0095] The shaping of the fibrous blank 5, 6 into a fibrous preform can be carried out by placing the fibrous blank 5, 6 in a mold. The mold used for shaping can conventionally also be used to carry out at least part of the densification of the fibrous preform, for example its consolidation.

[0096] The shaping of the fibrous blank 5, 6 is facilitated by the presence of the intermediate portion(s) 230, 431, 432. Indeed, the intermediate portion(s) 230, 431, 432 are more flexible than the core portion 220, 420. Thus, by having the intermediate portion(s) 230, 431, 432 more flexible at the periphery of the fibrous blank 5, 6, the fibrous blank 5, 6 deforms more easily and conforms more readily to the mold walls. In particular, the fibrous blank 5, 6 more easily follows the curves imposed by the mold. Thus, the intermediate portion(s) 230, 431, 432 located at the periphery of the fibrous blank 5, 6 also help to limit the risk of crushing the weave. The risk of crushing the weave is particularly high in the convex areas of the fibrous preform.Furthermore, since the fibrous blank 5, 6 is more deformable, it fills the densification mold correctly, thus limiting densification defects.

[0097] The resulting fibrous preform may have a convex face. Preferably, the skin adjacent to the intermediate portion forms a convex face.

[0098] Figure 3 partially illustrates a fibrous preform 50 arranged in a mold 8. The fibrous preform 50 is an example of a fibrous preform that can be obtained from the fibrous blank 5 described in connection with the first embodiment of the invention. The mold 8 has curved walls. Thus, the fibrous preform 50 has a convex face. In particular, the first skin 211 adjacent to the intermediate portion 230 forms a convex face. The second skin 212 opposite the intermediate portion 230 forms a concave face.

[0099] The fibrous preform can be consolidated or densified in a well-known manner by gaseous means through chemical vapor infiltration of the matrix, known as "CVI". The fibrous preform is placed in a furnace into which a reaction gaseous phase is admitted. The pressure and temperature prevailing in the furnace and the composition of the gaseous phase are chosen so as to allow the diffusion of the gaseous phase within the porosity of the preform to form at least part of the matrix by deposition, at the core of the material in contact with the fibers, of a solid material resulting from the decomposition of a constituent of the gaseous phase or from a reaction between several constituents, unlike the pressure and temperature conditions specific to CVD ("Chemical Vapor Deposition") processes which lead exclusively to deposition on the surface of the material.The formation of a SiC matrix can be obtained with methyltrichlorosilane (MTS) giving SiC by decomposition of MTS.

[0100] A densification process combining gas and liquid methods can be used in a well-known manner to facilitate implementation and limit manufacturing costs and cycles while obtaining satisfactory characteristics for the intended use. In this configuration, the fibrous preform is consolidated by gas as described above, then impregnated with a suspension or slurry ("slurry cast") containing, for example, SiC particles and organic binders, followed by infiltration with liquid silicon ("melt infiltration"). The densification can be carried out in a well-known manner by resin transfer molding (RTM) or by suspension transfer molding (STM).The fibrous preform may or may not have been previously consolidated, either by gas or other means. Densification can also be achieved using a well-established method: injection under a membrane, onto the previously consolidated fibrous preform, whether gas or other methods. This injection method allows for complete control of the quantity of resin or slurry injected, thus ensuring a precise fiber volume percentage. and adapted. Consequently, the mechanical characteristics of the part thus manufactured are improved, with low variability from one part to another.

[0101] A raw part made of composite material is thus obtained. The raw part made of composite material can be ceramic matrix (CMC) or organic matrix (CMO). [Fig. 4] partially illustrates an example of a raw part made of composite material 500 obtained by densification of the fibrous preform 50.

[0102] The raw part of composite material 500 comprises a part 5200. The part 5200 comprises a first skin 5211 and a second skin 5212. The fibrous reinforcement of the first skin 5211 of the part 5200 of the raw part 500 is formed by the first skin 211 of the part 200 of the fibrous blank 5. The fibrous reinforcement of the second skin 5212 of the part 5200 of the raw part 500 is formed by the second skin 212 of the part 200 of the fibrous blank 5.

[0103] The portion 5200 of the raw composite material 500 further comprises a core portion 5220 situated between the first skin 5211 and the second skin 5212 along the thickness direction DE. The core portion 5220 of the raw material 500 is directly adjacent to the second skin 5212 along the thickness direction DE. The fibrous reinforcement of the core portion 5220 of the portion 5200 of the raw material 500 is formed by the core portion 220 of the portion 200 of the fibrous blank 5.

[0104] The portion 5200 of the raw composite material 500 further comprises an intermediate portion 5230 situated between the core portion 5220 and the first skin 5211 along the thickness direction DE. The intermediate portion 5230 of the raw material 500 is directly adjacent to the first skin 5211 along the thickness direction DE. The intermediate portion 5230 of the raw material 500 is directly adjacent to the core portion 5220 along the thickness direction DE. The fibrous reinforcement of the intermediate portion 5230 of the portion 5200 of the raw material 500 is formed by the intermediate portion 230 of the portion 200 of the fibrous blank 5.

[0105] A composite material blank according to the first embodiment can be formed solely from the portion 5200. However, the composite material blank 500 according to the first embodiment of the invention can comprise several portions 5100, 5200 along the longitudinal direction DL. Portions such as the portion 5200 described above can be thicker than other portions. In particular, the composite material blank 500 can comprise several portions such as the portion 5200 described above along the longitudinal direction DL. These several portions 5200 can be adjacent to each other or separated by other portions different from the portion 5200 described above. In the example illustrated in [Fig. 4], the composite material blank 500 comprises a first portion 5100 and a second portion 5200 along the longitudinal direction DL. The second part corresponds to the 5200 section described previously. The second part 5200 is thicker than the first part 5100 along the thickness direction DE.

[0106] The first part 5100 of the raw part made of composite material 500 comprises a first skin 5111 and a second skin 5112. The fibrous reinforcement of the first skin 5111 of the part 5100 of the raw part 500 is formed by the first skin 111 of the first part 100 of the fibrous blank 5. The fibrous reinforcement of the second skin 5112 of the part 5100 of the raw part 500 is formed by the second skin 112 of the first part 100 of the fibrous blank 5.

[0107] The first portion 5100 of the composite material blank 500 further comprises a core portion 5120 situated between the first skin 5111 and the second skin 5112 along the thickness direction DE. The core portion 5120 of the blank 500 is directly adjacent to the second skin 5112 along the thickness direction DE. The core portion 5120 of the blank 500 is directly adjacent to the first skin 5111 along the thickness direction DE. The fibrous reinforcement of the core portion 5120 of the first portion 5100 of the blank 500 is formed by the core portion 120 of the first portion 100 of the fibrous blank 5.

[0108] At least one area is then removed from the raw composite material. The removed area includes at least a portion of the intermediate portion(s) and at least a portion of the skin adjacent to the intermediate portion(s). The removed area may include the entire intermediate portion. The removed area may include all of the intermediate portions. Thus, the final composite material part may be devoid of an intermediate portion. The core portion is retained in the final part. Preferably, the core portion is retained entirely in the final part.

[0109] Figures 5 and 6 illustrate examples of final parts made of composite material obtained by the process of the invention. The final part can be made of ceramic matrix composite (CMC) or organic matrix composite (CMO).

[0110] Fig. 5 illustrates an example of a final part in composite material 5000 obtained from the fibrous blank 5 according to the first embodiment of the invention.

[0111] The final part 5000 is obtained by removing an area from the raw part 500. The removed area includes at least part of the intermediate portion 5230 of the part 5200 of the raw part 500. In the example shown in [Fig. 5], the removed area includes the entire intermediate portion 5230 of the part 5200 of the raw part 500. The core portion 5220 of the part 5200 of the raw part 500 is retained in the final part 5000. The removed area includes at least part of the first skin 5211 of the part 5200 of the raw part 500. In the example shown in [Fig. 5], the removed area includes the entire first skin 5211 of the part 5200 of the raw part 500. We do not, of course, depart from the scope of the invention if the removed area includes only a part of the first skin 5211 of the part 5200 of the raw part 500. The second skin 5212 of the part 5200 of the raw part 500 is entirely retained in the final part 5000.

[0112] In the example shown in [Fig. 5], the removed area also includes a portion of the core portion 5120 of the first portion 5100 of the raw piece 500. Thus, the final piece 5000 comprises only a portion 5120p of the core portion 5120 of the first portion 5100 of the raw piece 500. The removed area includes at least a portion of the first skin 5111 of the first portion 5100 of the raw piece 500. In the example shown in [Fig. 5], the removed area comprises the entire first skin 5111 of the first portion 5100 of the raw piece 500. The second skin 5112 of the first portion 5100 of the raw piece 500 is entirely retained in the final piece 5000.

[0113] Thus, the final part 5000 comprises a first external face 5001 and a second external face 5002 opposite the first external face 5001. The first external face 5001 and the second external face 5002 are opposite along the thickness direction DE. The first external face 5001 corresponds to the boundary of the removed area. The second external face 5002 is defined by the second skin 5212 of the final part 5000. The second external face 5002 is also defined by the second skin 5112 of the first part 5100 of the final part 5000. The first external face 5001 may be convex. The second external face 5002 may be concave. The final part made of composite material 5000 may be a blade. Thus, the first external face 5001 can form at least part of the extrados of the blade and the second external face 5002 can form at least part of the intrados of the blade.

[0114] Fig. 6 illustrates an example of a final part in composite material 6000 obtained from the fibrous blank 6 according to the second embodiment of the invention.

[0115] The final part 6000 is obtained by removing a first zone and a second zone from the raw part obtained from the fibrous blank 6 according to the second embodiment of the invention.

[0116] The first removed area comprises at least a portion of the first intermediate portion of the raw part. In the example shown in [Fig. 6], the first removed area comprises only a portion of the first intermediate portion of the raw part. Thus, the final part 6000 comprises a portion 6431 of the first intermediate portion of the raw part. Of course, this does not depart from the scope of the invention if the first removed area comprises the entire first intermediate portion. In the example shown in [Fig. 6], the first removed area comprises the entire first skin of the second portion of the raw part. Of course, this does not depart from the scope of the invention. of the scope of the invention if the first area removed comprises only a part of the first skin of the second part of the raw piece.

[0117] The second removed zone comprises at least a portion of the second intermediate portion of the raw part. In the example shown in [Fig. 6], the second removed zone comprises only a portion of the second intermediate portion of the raw part. Thus, the final part 6000 comprises a portion 6432 of the second intermediate portion of the raw part. It is of course not beyond the scope of the invention if the second removed zone comprises the entire second intermediate portion. In the example shown in [Fig. 6], the second removed zone comprises the entire second skin of the second portion of the raw part. It is of course not beyond the scope of the invention if the second removed zone comprises only a portion of the second skin of the second portion of the raw part.

[0118] The core portion 6420 of the second part of the raw piece is retained in the final piece 6000.

[0119] In the example illustrated in [Fig. 6], the core portion 6320 of the first part of the raw material is retained in the final part 6000. Similarly, the first skin 6311 and the second skin 6312 of the first part of the raw material are retained in the final part 6000. It is clearly within the scope of the invention if the first removed area or the second removed area includes a portion of the core portion 6320 of the first part of the raw material. It is also within the scope of the invention if the first removed area includes all or part of the first skin 6311 of the first part of the raw material. Nor is it within the scope of the invention if the second removed area includes all or part of the second skin 6312 of the first part of the raw material.

[0120] Thus, the final part 6000 comprises a first external face 6001 and a second external face 6002 opposite the first external face 6001. The first external face 6001 and the second external face 6002 are opposite along the thickness direction DE. The first external face 6001 corresponds to the boundary of the first removed area. The second external face 6002 corresponds to the boundary of the second removed area. In the example shown in [Fig. 6], the first external face 6001 is also defined by the first skin 6311 of the first part of the final part 6000. In the example shown in [Fig. 6], the second external face 6002 is also defined by the second skin 6312 of the first part of the final part 6000. The final part made of composite material 6000 can be a blade.Thus, the first external face 6001 can form at least part of the extrados or intrados of the blade and the second external face 6002 can form at least part of the intrados or extrados of the blade.

[0121] The expression "between ... and ..." should be understood as including the boundaries.

Claims

Demands

1. A fiber blank (5) intended to provide at least part of the fiber reinforcement of a part made of composite material (5000), the fiber blank (5) being made in one piece by three-dimensional weaving between a plurality of warp yarns (51) extending along a longitudinal direction (DL) and a plurality of weft yarns (52) extending along a transverse direction (DT), the fiber blank (5) comprising a first skin (211) and a second skin (212) situated on either side of a core portion (220) along a thickness direction (DE) perpendicular to the longitudinal (DL) and transverse (DT) directions, the fiber blank (5) further comprising at least one intermediate portion (230) present between the core portion (220) and the first skin (211) along the thickness direction (DE),the fibrous blank (5) being characterized in that the warp / weft ratio of the core portion (220) is greater than the warp / weft ratio of at least one intermediate portion (230).

2. Fibrous blank (5) according to claim 1, wherein the warp / weft ratio of the core portion (220) is between 0.9 and 1.

1.

3. Fibrous blank (5) according to claim 1 or 2, wherein the warp yarns (51) of at least an intermediate portion (230) separate the weft yarns (52) into groups of at least two weft yarns (52) in each warp yarn plane (51) perpendicular to the transverse direction (DT).

4. Fibrous blank (5) according to claim 3, wherein the number of warp yarn planes (52) perpendicular to the transverse direction (DT) in at least one intermediate portion (230) is greater than the number of warp yarn planes (52) perpendicular to the transverse direction (DT) in the core portion (220).

5. Fibrous blank (5) according to any one of claims 1 to 4, wherein the second skin (212) is intended to form the fibrous reinforcement of the intrados surface of a blade or a blade.

6. Fibrous blank (5) according to any one of claims 1 to 5, wherein the core portion (220) is adjacent to the second skin (212) along the thickness direction (DE) and the intermediate portion (230) is adjacent to the first skin (211) along the thickness direction (DE).

7. Fibrous blank (6) according to any one of claims 1 to 5, wherein the fibrous blank (6) comprises a first intermediate portion (431) adjacent to the first skin (411) along the thickness direction (DE) and a second intermediate portion (412) adjacent to the second skin (412) along the thickness direction (DE).

8. Fibrous blank (5; 6) according to any one of claims 1 to 7, wherein the weave structure of the core portion (220; 420) and of the intermediate portion(s) (230; 431, 432) is of the interlock type.

9. A fibrous blank (5; 6) according to any one of claims 1 to 8, the fibrous blank (5; 6) comprising at least a first part (100; 300) and a second part (200; 400) along the longitudinal direction (DL), the first part (100; 300) being devoid of intermediate portions so that the first part (100; 300) of the fibrous blank (5; 6) is thinner than the second part (200; 400) of the fibrous blank (5; 6) along the thickness direction (DE).

10. A method for manufacturing a part (5000; 6000) of composite material comprising: - producing a fibrous blank (5; 6) according to any one of claims 1 to 9, - placing the fibrous blank (5; 6) in a mold (8), then - densifying the fibrous blank with a matrix so as to obtain a raw part (500) of composite material comprising a core portion (5220) whose fibrous reinforcement is formed by the core portion (220; 420) of the fibrous blank (5; 6), at least one intermediate portion (5230) whose fibrous reinforcement is formed by at least one intermediate portion (230; 431, 432) of the fibrous blank (5; 6), and a first skin (5211) and a second skin (5212) whose fibrous reinforcement is formed respectively the first skin (211; 411) and the second skin (212; 412) of the fibrous rudiment (5;6), - the removal of at least one area of ​​the raw part (500) in composite material, said area comprising at least part of the at least one intermediate portion (5230) and at least part of the first skin (5211).; 23

11. Method according to claim 10, wherein the resulting composite material part (5000; 6000) has a ceramic matrix.

12. A method according to claim 10, wherein the resulting composite material part (5000; 6000) is organic matrix.

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