Fibrous reinforcement for the manufacture of composite parts intended to be articulated with other parts

Abstract

The present invention relates to a fibrous preform of a core portion of a fibrous reinforcing material of a composite material part, which has an elongated shape along the longitudinal direction X and is formed by first yarns C1 to C16 extending along the longitudinal direction and second yarns t1 to t8 crossing the first yarns. In the fibrous preform, the preform includes two longitudinal ends intended for articulation joining with other parts and an intermediate region located between the longitudinal ends. Each longitudinal end has a thickness greater than the thickness of the intermediate region. The intermediate region includes first non-woven yarns C5 to C12. Each longitudinal end includes a reinforcing segment 102c including a three-dimensional weave of a first non-woven yarn and a second yarn of the reinforcing segment.

Description

[Technical Field]

[0001] The present invention relates to a fibrous preform intended to form part of the fibrous reinforcement of a part made from composite material, the part being intended to be articulated at its end with another part, and to an associated manufacturing method. [Background technology]

[0002] The use of composite materials instead of metal materials can be proposed with a view to weight reduction, which is always a concern in the special case of aircraft parts. From this perspective, U.S. Patent Application Publication No. 7,704,429 proposes the manufacture of a landing gear strut made of composite material with a region called a fork, intended for articulation with other parts and for force introduction, formed by a laminated structure with the insertion of layers between primary layers extending through the main body of reinforcement. Nevertheless, this solution can have drawbacks. In fact, a fork with a laminated structure can lead to an increase in the size of the force introduction region compared to metal parts in order to avoid the risk of delamination. In this case, weight reduction of the entire system becomes less attractive, and component integration becomes more limited due to the increased bulk density. Another problem is that the proposed manufacturing techniques involve a considerable amount of manual intervention, which can lead to incompatibilities and increased costs. Finally, the mechanical performance of the composite material proposed here can be improved, especially in terms of compressive strength over the intermediate region of the part's length, known as the common region. One option to address this is to add material to the common area, which has a mass penalty and is therefore not entirely satisfactory. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 7,704,429 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention proposes to address all or some of the aforementioned drawbacks. [Means for solving the problem]

[0005] The present invention relates to a fibrous preform for a core part of a fibrous reinforcement for a composite material part, the fibrous preform having an elongated shape along its longitudinal direction and formed by first threads extending along the longitudinal direction and second threads crossing the first threads, the preform having two longitudinal ends intended for articulation with other parts and an intermediate region located between these two longitudinal ends, each longitudinal end having a thickness greater than the thickness of the intermediate region, the intermediate region comprising a reinforcing segment comprising first nonwoven threads, each longitudinal end comprising a three-dimensional weave of the first threads and the second threads of this reinforcing segment.

[0006] The present invention proposes an optimized design of a core preform of fiber reinforcement for a core belt assembly type, based on three-dimensional weaving technology and based on an excess thickness in the articulation area compared to the intermediate or common area, in order to obtain improved resistance to force introduction areas. This reinforcement segment allows for a significant improvement in the compressive performance of the intermediate area compared to a structure obtained entirely by three-dimensional weaving. The present invention also limits or even avoids the weaving of secondary yarns in the intermediate area, thereby reducing material consumption and post-weaving processes such as cutting. The primary yarns of the reinforcement segment are woven into the three-dimensional weave at the longitudinal ends to obtain the desired resistance to forces in the articulation area.

[0007] In one exemplary embodiment, the fibrous preform comprises textile skins located on either side of a reinforcement segment, the first threads of which are held by threads coming from said textile skins.

[0008] Such features can advantageously improve the impact resistance of the fibrous reinforcement.

[0009] In particular, the woven fabric skin may comprise folded, unconnected transverse fibrous segments that form locating surfaces for the fibrous belt texture on the upper and lower sides of the preform.

[0010] Such features help improve the quality of the interface between the core and the belt, further improving the mechanical performance of the part.

[0011] In one exemplary embodiment, the preform further comprises a transition region between each longitudinal end and the intermediate region comprising an additional layer of the first yarn compared to that present in the intermediate region woven with the second yarn at the two longitudinal ends.

[0012] Such a feature advantageously makes it possible to achieve a greater increase in the thickness of the longitudinal ends and therefore to further improve the mechanical properties of the part.

[0013] In an exemplary embodiment, the preform is made from carbon yarn.

[0014] The present invention also provides a method for producing a fibrous reinforcement for a composite material component, comprising the steps of: As mentioned above, the present invention relates to a method in which a woven fiber belt texture is positioned on the core portion preform, the belt texture defining loops around the core portion preform at its longitudinal ends so as to define free spaces intended for articulation with other components.

[0015] In one exemplary embodiment, the belt texture is made from carbon yarn.

[0016] The invention also relates to a method for manufacturing a composite part intended to be articulated with another part, comprising the steps of: forming a fibrous reinforcement as described above; and forming a matrix in the porosity of the fibrous reinforcement thus obtained.

[0017] In an exemplary embodiment, the matrix is ​​an organic matrix.

[0018] In one exemplary embodiment, the component is a landing gear strut, a portion of a landing gear strut, or a brake bar. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 shows diagrammatically an example of a fibrous texture intended to form a preform according to the invention. [Figure 2] FIG. 2 shows a schematic cross section of the texture of FIG. [Figure 3A] FIG. 3A shows, in a schematic and partial manner, a first step of a possible shape for the texture of FIGS. [Figure 3B] FIG. 3B shows, in a schematic and partial manner, a second step of a possible shape for the texture of FIGS. [Figure 3C] FIG. 3C shows diagrammatically and partially a third step of possible shapes for the texture of FIGS. 1 and 2 as well as the positioning of the belt. [Figure 4] FIG. 4 is a perspective view of an example of a core belt assembly type fibrous reinforcement according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] FIG. 1 shows a woven fibrous texture 100 intended to form, after molding, a fibrous preform 200 (see FIGS. 3B, 3C, and 4) of a fibrous reinforcement core for a composite material part. Possible texture shapes are described below in connection with FIGS. 3A-3C. The texture 100 and the preform 200 have an elongated shape extending along the longitudinal direction X and can be obtained by weaving into a single part. The texture 100 and the preform 200 comprise, successively along the longitudinal direction X, a first longitudinal end 103a, a middle zone ZM, and a second longitudinal end 103b. In the illustrated example, a first transition zone ZTa exists between the first end 103a and the middle zone ZM, and a second transition zone ZTb exists between the middle zone ZM and the second end 103b. The presence of the transition zones ZTa and ZTb is considered in the illustrated embodiment but remains optional within the framework of the present invention. According to one example, each possible transition region ZTa, ZTb can have a length La, Lb constituting 1% to 20% of the length L0 of the texture 100 or preform 200, and each end 103a; 103b can have a length L2, L3 constituting 1% to 20% of the length L0. The lengths are measured along the longitudinal direction X. The intermediate region ZM can be located in the middle of the length of the texture 100 or preform 200 and can be centered with respect to a plane P50 perpendicular to the longitudinal direction X. In the example shown in FIG. 1, the thickness e2 of the first end 103a is greater than the thickness e1 of the intermediate region ZM. The thickness e3 of the second end 103b is less than the thickness e2 but greater than the thickness e1. The thickness is measured along the thickness direction (E direction) and corresponds to the smallest dimension. In one example, the ratio e2 / e1 can be greater than 1 and less than or equal to 4, for example, 1.5 to 2.5, and the ratio e3 / e1 can be greater than 1 and less than or equal to 4, for example, 1.5 to 2.5.

[0021] The woven architecture differs between the end portions 103a and 103b, the transitional regions ZTa and ZTb, and the intermediate region ZM, as described in more detail below. The end portions 103a and 103b are obtained by three-dimensionally weaving first yarns extending along the longitudinal direction X with second yarns that cross the first yarns, for example, in an "interlock" weaving pattern. In the illustrated example, some of the first yarns present in the end portions 103a and 103b form reinforcement segments 102c in the intermediate region ZM, which are not woven with the second yarns in this segment 102c. The first yarns may extend substantially linearly within the reinforcement segments 102c. The reinforcement segments 102c may comprise a unidirectional layer of the first yarns. Generally, the first nonwoven yarns may be the majority (more than 50%) of the number in the intermediate region ZM, for example, representing at least 80% of the number of all yarns present in the intermediate region ZM. Secondary yarns are added to the longitudinal ends 103a, 103b to weave through the primary yarns of the reinforcing segment 102c. These additional secondary yarns correspond to additional layers of yarn, possibly compared to the secondary yarn layer present in the intermediate zone ZM. Figure 2 shows a cross-sectional view of a possible weave configuration in the intermediate zone ZM, relative to the longitudinal direction X. The texture 100 comprises a central segment 110 having, on both sides 111 thereof, two positioning edges 120 each comprising unconnected lateral segments 160a, 160b, separated by unconnected regions 140 that allow spacing of these segments 160a, 160b relative to each other. The positioning edges 120 and the central segment 110 are offset along the width direction L, while the unconnected segments 160a, 160b are offset along the thickness direction E. The central segment 110 comprises reinforcing segments 102c comprising primary nonwoven yarns C5-C12. Woven fabric skins 102a, 102b, obtained by three-dimensional weaving, for example by "interlock" weaving, are present within the central segment 110 and extend beyond it to form unconnected segments 160a, 160b. Skins 102a, 102b are formed by weaving between second yarns t1-t8 extending along direction L and first yarns C1-C4 and C13-C16 extending along longitudinal direction X.In general, it will be recognized that the number of yarn layers and weaving patterns shown are provided by way of example only and may be modified without departing from the scope of the present invention. The skins 102a, 102b are arranged in the intermediate region ZM, and their extension ranges define a single piece of fabric extending across the entire width and thickness of the texture 100 or preform 200 at the ends 103a, 103b. The yarns C5-C12 of the reinforcement segment 102c are arranged between the skins 102a, 102b and are held together by the yarns coming from there. It should be noted that the yarn t4 extends into the first skin 102a outside the central segment 110 and is deflected to exit this first skin 102a and join the set 102c of yarns C5-C12 within the central segment 110. Similarly, thread t5 extends into the second skin 102b outside the central segment 110 and is deflected to exit this second skin 102b and join the set 102c of threads C5-C12 in the central segment 110 opposite thread t4. Thus, an encapsulation of the reinforcement segment 102c formed by threads C5-C12 is obtained between the skins 102a and 102b, with these threads C5-C12 held in place by the deflected threads t4-t5. In the illustrated example, the central segment 110 includes the first skin 102a, the nonwoven thread segment 102c, and the second skin 102b in succession along the thickness direction E. Note that the nonwoven thread segment 102c is present only in the central segment 110 and not in the positioning edge 120. This allows for saving of threads in this area and avoids a manual cutting step when these threads are woven. As mentioned above, the yarns C5-C12 are unwoven over only a portion of the length of the first texture 100 or preform 200, over its intermediate region ZM and possibly over the transition regions ZTa, ZTb, but are woven at the longitudinal ends 103a; 103b. When the yarns C5-C12 are nonwoven, their length may be 50% or more, for example 75%, of the length LO of the texture 100 or preform 200.

[0022] 3A-3C show in a simplified manner the shaping of the texture 100 of FIGS. 1 and 2 and the positioning of the second belt texture 40 to obtain a preform 200. It should be understood that this configuration is symmetrical with respect to the directions L and E. In the example considered, on a shape (not shown), the non-connected segments 160a, 160b are deployed so as to form an angle of substantially 90° with respect to the direction L, so that the non-connected segments 160a, 160b are positioned at the height of the segment 102c. This height is obtained along the direction L. The preform 200 has a substantially planar positioning surface 130, at the same level as the non-connected segments 160a, 160b and the segment 102c located between them and thus defining the abutment surface of the belt texture 40. The preform 200 may be I-shaped (called a double-angle shape) in cross section relative to the longitudinal direction X. In the example of FIG. 1, there are transition regions ZTa and ZTb between the intermediate region ZM and the end portions 103a and 103b. Reinforcement segments 102c are also present in the transition regions ZTa and ZTb, but the skins 104a1, 104a2, 104b1, and 104b2 are thicker in this region than in the skins 102a and 102b of the intermediate region ZM. In fact, an additional layer of first yarn is added in this region compared to that present in the intermediate region ZM. The layer of first yarn added in this region is gradually woven with the second yarn, as shown, to form the skins 104a1, 104a2, 104b1, and 104b2, which extend into the end portions 103a and 103b, allowing for the desired thickness for the end portions when significant excess thickness is required.

[0023] FIG. 4 shows an example of a core belt assembly according to the present invention, forming the fibrous reinforcement 300 of the resulting part. The woven belt texture 40 is positioned around the preform 200 obtained after forming the texture 100 by folding the unconnected segments 160a, 160b. The texture 40 can have the shape of a strip wrapped around the preform 1. Once positioned, the texture 40 abuts the positioning surface 130. The texture 40 can be in the form of a single strip of fabric, but it is within the scope of the present invention to have several strips arranged end-to-end or side-by-side. The texture 40 can also be obtained by three-dimensional weaving, for example, using an "interlock" weaving pattern. The texture 40 defines a closed loop around the preform 200, defining a free space 42 intended for articulation with other parts. Inserts (not shown) can be temporarily used at the longitudinal ends 103a, 103b, and a second texture 40 can be wrapped around them to ensure the desired shape for the end regions. The ends 103a, 103b may have a curved shape, e.g., substantially circular, as shown. The transverse dimension DT of the positioning surface 130 increases from the first end 103a to the intermediate region ZM, e.g., is greatest at least near a mid-length plane P50 of the preform 200, on a cross section perpendicular to the longitudinal direction X and located between planes P40 and P60 at 40% and 60% of the length LO, and then decreases toward the second end 103b. The positioning surface 130 defines a transverse fin for positioning the belt texture 40. The volume ratio between the warp and weft yarns of the preform 200 and the belt texture 40 may be similar, e.g., with a difference of at most 10%. These volume ratios correspond to the ratio [volume occupied by warp yarns] / [volume occupied by weft yarns] for each considered fabric.

[0024] Densification of the preform 200 and the entire texture 40 is then carried out by introducing a resin, such as an epoxy resin, followed by its crosslinking if it is a thermosetting resin, or by cooling if it is a thermoplastic resin. The formation of the matrix can be achieved by resin transfer molding techniques, which correspond to techniques known per se. The composite part thus obtained is intended to be articulated at its longitudinal ends with other parts and to be subjected to tensile and compressive forces. The fibrous reinforcement of the part can be formed from carbon yarns, and the part can have an organic matrix as described above. The part may or may not be intended for aeronautical applications. The part can be, for example, a connecting rod, a landing gear strut or its components, or a brake bar. The obtained part can be attached to other parts by positioning a hinge pin for connection to the other part and a contact insert for this pin through the free space 42. The present disclosure also includes the following inventions. The first aspect is A method for manufacturing a fibrous reinforcement (300) for a composite material component, comprising: The method comprises positioning a woven fiber belt texture (40) on a fibrous preform (200) of a core portion of a fibrous reinforcement (300) for a composite material part; The fibrous preform has an elongated shape along a longitudinal direction (X) and is formed by first threads (C1 to C16) extending along the longitudinal direction and second threads (t1 to t8) crossing the first threads, the fibrous preform having two longitudinal ends (103a; 103b) intended for articulation with other parts and an intermediate region (ZM) located between the two longitudinal ends, each of which has a thickness (e1) greater than the thickness of the intermediate region. a method for forming a reinforcement segment (102c) having a thickness (e2; e3), the intermediate region comprising first nonwoven yarns (C5-C12), each longitudinal end comprising a three-dimensional weave of the first nonwoven yarns (C5-C12) of the reinforcement segment and a second yarn, the woven fiber belt texture defining loops around the fibrous preform of the core portion so as to define free spaces (42) at the two longitudinal ends intended for articulation with other components. The second aspect is A method according to a first aspect, wherein the fibrous preform comprises textile skins (102a; 102b) located on both sides of the reinforcing segment (102c), and first yarns (C5-C12) of the reinforcing segment are held by yarns (t4; t5) coming from the textile skins. The third aspect is A method according to a second aspect, wherein the woven fabric skin (102a; 102b) comprises folded, unconnected transverse fibrous segments (160a; 160b) forming positioning surfaces (130) for a fibrous belt texture (40) on the upper and lower sides (111) of the fibrous preform. The fourth aspect is A method according to any one of the first to third aspects, wherein the fibrous preform further comprises a transition region (ZTa; ZTb) between each longitudinal end (103a; 103b) and the intermediate region (ZM) comprising an additional layer of first yarns compared to those present in the intermediate region woven with second yarns at the two longitudinal ends. The fifth aspect is The method according to any one of the first to fourth aspects, wherein the fibrous preform is made from carbon yarn. The sixth aspect is The method of any one of the first to fifth aspects, wherein the woven fiber belt texture (40) is made from carbon yarn. A seventh aspect is 1. A method for manufacturing a composite part intended to articulate with another part, comprising: The method comprises: Forming a fibrous reinforcing material (300) according to any one of the first to sixth aspects; and forming a matrix in the porosity of the fibrous reinforcement thus obtained. The eighth aspect is A method according to a seventh embodiment, wherein the matrix is ​​an organic matrix. A ninth aspect is The method of the seventh or eighth aspect, wherein the part is a landing gear strut, a portion of a landing gear strut, or a brake bar.

Claims

1. A method for manufacturing a fibrous reinforcement (300) for a composite material component, comprising: The method comprises positioning a woven fiber belt texture (40) on a fibrous preform (200) of a core portion of a fibrous reinforcement (300) of a composite material component; The fibrous preform has an elongated shape along a longitudinal direction (X) and is formed by first threads (C1 to C16) extending along the longitudinal direction and second threads (t1 to t8) crossing the first threads, the fibrous preform having two longitudinal ends (103a; 103b) for articulation with other parts and an intermediate region (ZM) located between the two longitudinal ends, each of the longitudinal ends having a thickness (e1) greater than the thickness of the intermediate region. a woven fiber belt texture having a thickness (e2; e3) greater than 100 mm, the intermediate region comprising reinforcing segments (102c) comprising first nonwoven yarns (C5-C12), each longitudinal end comprising a three-dimensional weave of the first nonwoven yarns (C5-C12) of the reinforcing segments with second yarns, the woven fiber belt texture defining loops around the fibrous preform of the core portion so as to define free spaces (42) at the two longitudinal ends for articulation with other components.

2. 2. The method according to claim 1, wherein the fibrous preform comprises textile skins (102a; 102b) located on both sides of the reinforcing segment (102c), and the first nonwoven yarns (C5-C12) of the reinforcing segment are held by yarns (t4; t5) coming from the textile skins.

3. 3. The method of claim 2, wherein the woven fabric skin (102a; 102b) comprises folded, unconnected transverse fibrous segments (160a; 160b) forming locating surfaces (130) for the woven fiber belt texture (40) on the upper and lower sides (111) of the fibrous preform.

4. 2. The method of claim 1, wherein the fibrous preform further comprises a transition region (ZTa; ZTb) between each longitudinal end (103a; 103b) and the intermediate region (ZM), the transition region (ZTa; ZTb) comprising an additional layer of first yarns.

5. The method of claim 1 , wherein the fibrous preform is made from carbon yarn.

6. The method of claim 1 , wherein the woven fiber belt texture (40) is made from carbon yarn.

7. 1. A method of manufacturing a composite material part for articulation with another part, comprising the steps of: The method comprises: forming a fibrous reinforcement (300) by the method of any one of claims 1 to 6; forming a matrix having porosity from the fibrous reinforcement thus obtained.

8. The method of claim 7 , wherein the matrix is ​​an organic matrix.

9. The method of claim 7 , wherein the composite part is a landing gear strut, a portion of a landing gear strut, or a brake bar.

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