Method for manufacturing a composite material part intended to be articulated with other parts

Abstract

In a method for manufacturing a fibrous preform for a component, the method comprises weaving a first core texture of an elongated shape extending in a longitudinal direction, wherein in cross-section, the first core texture comprises a central portion 10 having on both sides thereof two edges each comprising two unconnected fiber portions 16a; 16b, and shaping a first fiber texture, wherein the shaping of the first fiber texture involves at least opening unconnected transverse portions to form positioning surfaces 30; 130 defined by a plurality of open transverse portions, or defined by an extension 18a of the central portion and the central portion 110 and located between the plurality of open transverse portions and defined by insertion fiber portions, positioning a second woven belt fiber texture 40 across the plurality of open transverse portions and the insertion fiber-like portions, wherein the second woven belt fiber texture forms a loop around the shaped first fiber texture so as to define an empty space 42 intended for articulation to other components at a longitudinal end between the first fiber texture and the second woven belt fiber texture.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a composite part preform intended to be articulated at its end to other parts, and to a method for manufacturing said composite part.

Background Art

[0002] The use of composite materials in place of metallic materials can be proposed with a view to weight reduction, which is always a concern in the specific case of aircraft parts. From this point of view, Patent Document 1 (U.S. Patent No. 7,704,429) proposes the manufacture of a landing gear strut made of a composite material having a region called a yoke, this yoke being intended for articulation and force introduction with other parts and being formed by a laminated structure involving the insertion of a layer between primary layers extending the body of the reinforcement. Nevertheless, this solution can have drawbacks. In fact, a yoke having a laminated configuration can lead to an increase in the size of the force introduction area compared to metallic parts in order to avoid the risk of delamination. In this case, the weight reduction of the whole system becomes less interesting and the integration of the parts becomes more restrictive due to the increase in bulk density. Another problem is that the proposed manufacturing technique involves a significant amount of manual intervention which can lead to incompatibilities and cost increases. Finally, the mechanical performance of the composite materials proposed herein can be improved, particularly with regard to the compressive strength over the intermediate region of the length of the part, called the common region. One option to address this is to add material to the common region, which is disadvantageous from a mass point of view and thus does not provide complete satisfaction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention proposes to address all or part of the aforementioned drawbacks.

Means for Solving the Problem

[0005] In a method for manufacturing a fibrous preform for a composite part intended to be articulately joined to other parts, the method comprises: forming by weaving a first fibrous core texture having an elongated shape extending in the longitudinal direction, the first fibrous core texture comprising, in cross-section, a central portion having on both sides thereof two positioning edges each having two unconnected transverse fibrous portions; shaping a first fibrous texture, the shaping of the first fibrous texture involving at least opening the unconnected transverse portions to form a positioning surface defined by a plurality of open transverse portions, or defined by an extension of the central portion and the central portion, or defined by insertion fiber portions located between the plurality of open transverse portions; positioning a second woven belt fiber texture across the plurality of open transverse portions and the insertion fiber-like portions, the second woven belt fiber texture being shaped to form a loop around the shaped first fibrous texture so as to define an empty space intended for articulation to other parts at a longitudinal end between the first fibrous texture and the second woven belt fiber texture.

[0006] The present invention proposes a solution based on an assembly between a core and a belt, each resulting from a weaving operation, having a belt positioning surface formed by an insertion part and open unconnected parts located on both sides thereof. Such a solution provides a good-quality interfacial surface for the assembly, ensures good retention of the composite material parts, and in particular enables an improvement in mechanical performance, especially with regard to compressive strength, without being disadvantageous in terms of the mass of the structure compared to Patent Document 1 (US Patent No. 7,704,429). In particular, by avoiding the use of a third filling material between the plurality of open parts, it is advantageous to have a positioning surface of substantially flat shape due to the presence of the insertion part. The unconnected parts make it possible to increase the rigidity (optimization of inertia) along all the force axes of the part after molding. The belt-type technology according to the present invention also makes it possible to be more economical in terms of manufacturing costs than the solutions described in the prior art.

[0007] According to an example, each positioning edge further comprises an insertion fiber texture that extends in a central part and is located between some unconnected transverse fiber parts, and molding further comprises cutting this insertion fiber texture so as to form the insertion fiber part.

[0008] According to this example, the insertion part is formed by the remaining fabric extension of the central part within the positioning edge resulting from the cutting of the insertion fiber texture.

[0009] According to a variant embodiment, the central part comprises a fabric skin and a set of non-woven yarns located between the fabric skins and held together by the yarns coming therefrom, and the fabric skin extends into the positioning edge beyond the central part to form unconnected transverse fiber parts, and these unconnected parts are opened so as to be folded up to the height of the set of non-woven yarns during molding.

[0010] According to this variant embodiment, the insertion part is formed by the central part itself located at the same level as the open unconnected parts, and the need to perform the above-described cutting operation can be avoided.

[0011] Furthermore, the nonwoven yarn sets form reinforcing portions that enable further improvement of the compressive strength as compared to structures obtained entirely by three-dimensional weaving.

[0012] In an exemplary embodiment, the unconnected transverse fiber portion is formed by weaving a first yarn and a second yarn, has a first volume ratio of the first yarn to the second yarn, the second texture is formed by weaving the first yarn and the second yarn, has a second volume ratio of the first yarn to the second yarn, and the relative difference between the first volume ratio and the second volume ratio does not exceed 25%, for example, does not exceed 10%.

[0013] Such features help further improve the mechanical strength of the resulting composite material parts.

[0014] In an exemplary embodiment, the first texture and the second texture are made of carbon yarns.

[0015] The present invention also relates to a method for manufacturing a composite material part intended to be articulated to other parts, forming a fibrous preform for a part obtained by implementing the method as described above, and forming a matrix in the porosity of the fibrous preform thus obtained.

[0016] In an exemplary embodiment, the matrix is organic.

[0017] In an exemplary embodiment, the part is a landing gear strut, a segment of a landing gear strut, or a brake bar.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 3A

Figure 3B

Figure 3C

Figure 3D

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Figure 6A

Figure 6B

Figure 6C

Mode for Carrying Out the Invention

[0019] Figure 1 shows an example of a first fiber texture 1 that can be used in relation to the present invention. The first texture 1 has an elongated shape extending along the longitudinal direction X. This can be obtained by an integral three-dimensional weaving by providing a non-connected region, as will be described below. The term "three-dimensional weaving" or "3D weaving" means a weaving method in which at least some of the first yarns directed in the longitudinal direction X join the second lateral yarns to the first yarns on some layers of the second yarns. Such weaving can be performed on a Jacquard loom by a method known per se. The first texture 1 is intended to form the core of the fibrous reinforcement of the part to be obtained. For example, the first texture 1 can be formed using an "interlock" weaving pattern.

[0020] The first texture 1 has a curved shape, for example substantially circular, and has longitudinal ends 3 which are intended to define, in the resulting part, an empty space dedicated to articulation with other parts. In the example shown, the longitudinal ends 3 are of substantially the same size, but those skilled in the art will recognize that other variant embodiments are possible, and in particular that the present invention can be applied to parts having longitudinal ends of different sizes. The first texture 1 can be in the form of a strip, and FIG. 2 shows a cross-section transverse to the longitudinal direction X. The first texture 1 comprises a central part 10 having, on both its sides 11, two edges 12 intended for the positioning of a second texture, called positioning edges 12. The central part 10 also extends along the longitudinal direction X, like the two edges 12. The central part 10 is located between the two edges 12. In the example shown, not only the edges 12 but also the central part 10 are offset along the width (direction L) of the first texture. Each positioning edge 12 has, in the example shown along the thickness of the first texture 1 (direction E) corresponding to its minimum dimension, a first unconnected transverse fiber part 16a, an insertion fiber texture 18, and a second unconnected transverse fiber part 16b, continuously. A first unconnected region 14a exists between the first part 16a and the texture 18, and a second unconnected region 14b exists between the texture 18 and the second part 16b. Weaving between the layers of threads of the texture 18 and the parts 16a, 16b is intentionally omitted in the unconnected regions 14a, 14b so that it can be opened as described later. The unconnected regions 14a, 14b start from the sides 11. Each of the parts 16a, 16b extends beyond the sides 11 into the central part 10. In the example shown, the parts 16a, 16b and the insertion texture 18 are obtained by three-dimensional weaving like the central part 10, but if not, without departing from the scope of the present invention, in particular, the insertion texture can be formed from a layer of non-woven threads (a one-direction layer of threads). It should be noted that the unconnected regions 14a, 14b can extend over all or part of the length of the first texture 1, and in particular over at least 50% of the length LD of the first texture. The unconnected regions 14a, 14b can in particular be present on the middle region ZM of the length of the first texture 1.The example considered relates to the case where the height of the unconnected regions 14a, 14b measured along the direction L does not vary along the longitudinal direction X, in which case, particularly in the specific case where the longitudinal ends 3 have different dimensions, it does not depart from the scope of the invention. In particular, the height of the unconnected regions 14a, 14b may vary so as to reach a maximum in the intermediate region ZM, thus further promoting the quality of the interface with the belt and thus the mechanical properties of the common region, particularly the inertia of the core, and thus increasing the resistance to buckling under a compressive load or in a vibration mode. The possible structure of the first texture 1 has been described above, focusing hereinafter on the possible shapes in connection with FIGS. 3A to 3D in order to prepare for the positioning of the second belt texture.

[0021] As shown in FIG. 3A, the first texture 1 is positioned within a first tool 20 having two segments 22 intended to abut against the first texture 1. More precisely, the central portion 10 is held between the two segments 22, whereby, if desired, a compression pressure can optionally be applied thereto to adjust the fiber rate. The two segments 22 can be biased along direction E as shown. The segments 22 can be substantially flat and have a surface 22a that abuts the central portion 10 and a curved surface 22b that extends in a direction opposite to the first texture 1 from the surface 22a. The surface 22b defines a region 24, particularly in the vicinity of the positioning edge 12, where the unconnected portions 16a, 16b are intended to be draped during the cutting of the insert texture 18. Thus, as illustrated in FIG. 3B, the unconnected portions 16a, 16b are spaced apart from each other so as to position them on the region 24 of each segment 22 and thus release them from the insert texture 18. The unconnected portions 16a, 16b folded over the region 24 are held in this region 24 by means known per se, for example by clamping. Next, as shown in FIG. 3C, the insert texture 18 is cut along the cutting line LD. This cutting can be performed by water jet cutting, but those skilled in the art will recognize that other techniques are possible. As shown, the cutting of the insert texture 18 can be flush with the unconnected portions 16a, 16b held on the segment 22. Furthermore, due to the curved shape of the surface 22b, the inarticulate joint portions 16a, 16b extend away from the cutting line LD, thus ensuring that any risk of damage during this operation is avoided. The cutting residue of the texture 18 forms an insertion portion 18a located between the unconnected portions 16a, 16b and functions as a contact surface for the belt texture. The portion 18a is located at the fabric extension of the central portion 10. The fabric portion 18a can have a length short enough to have sufficient rigidity to maintain a straight shape along direction L in the absence of any holding tool.

[0022] When this cutting is performed, the first texture is extracted from the tool 20 and positioned between two shaped parts 23 of a second separate tool 21, which is a tool for shaping the core of the part to be obtained. The shaped parts 23 can be offset along the direction E, as shown in the figure. Figure 3D shows this shaping, where the unconnected parts 16a and 16b are opened on the shaped parts 23 so as to form transverse fins, and the first texture 13 thus shaped is shaped to have an I-shaped cross-section (referred to as a double angle shape). In the example shown, each of the opened unconnected parts 16a, 16b forms an elbow with the central part 10 at an angle substantially equal to 90° with respect to the direction L. The shaped first texture 13 defines a positioning surface 30 on either side of the central part 10 at the positioning edge 12, where it is intended that the second belt texture be deposited. The positioning surface 30 is defined by the inserted part 18a that extends from the opened unconnected parts 16a, 16b and the central part 10 that can fill the lack of material resulting from opening the unconnected parts 16a, 16b. This provides a good interface surface between the belt and, in particular, the substantially flat-shaped positioning surface 30 as illustrated in Figure 3D. The example described above uses two different tools, one for cutting and the other for shaping the first texture, but it does not depart from the scope of the present invention if the same tool is used for these two operations. This method continues, as shown in Figure 4, by positioning a second woven belt fiber texture 40 around the first texture 13 thus shaped by the tool 21. The second texture 40 can have the shape of a strip wound around the shaped first texture 13. When positioned, the second texture 40 abuts not only the opened parts 16a, 16b but also the inserted part 18a, thereby providing a good interface surface between the two textures. The second texture 40 can be in the form of a single strip of cloth, but it does not depart from the scope of the present invention if it is in the form of several strips arranged end to end or side by side.The second texture 40 can also be obtained, for example, by three-dimensional weaving using an "interlock" pattern. The second texture 40 defines a closed loop around the first texture 13, and this first texture is shaped to define an empty space 42 intended for articulation to other components. Inserts (not shown) can be temporarily used at the longitudinal ends 3, and the second texture 40 can be wrapped around them to ensure the desired shape for the end regions. As described above, the volume ratio between the warp and weft of each of the first texture 11 and the second texture 40 can be made the same. These volume ratios correspond to the ratio of [volume occupied by the warp] / [volume occupied by the weft] for each of the textures considered.

[0023] Then, together with the tool 21, a counter-mold is positioned around the assembly of the two textures 13 and 40 so as to define a cavity for introducing the matrix material, and then this assembly is densified by introducing a resin such as, for example, an epoxy resin and then, in the case of a thermosetting resin, cross-linking it or, in the case of a thermoplastic resin, cooling it. The form of the matrix can be carried out by resin transfer molding techniques corresponding to techniques known per se. In this way, a composite part is obtained, and this part is intended to be articulated to other parts at its longitudinal ends. The fibrous reinforcement of the part can be formed of carbon yarns, and the part can have an organic matrix as described above. The part may or may not be for aerospace applications. The part can be, for example, a connecting rod, a landing gear strut or its components, or a brake bar. The part can be intended to mainly receive tensile and compressive forces during operation. The obtained part can be attached to other parts by positioning a hinge pin for connection to other parts and a contact insert for this pin through the empty space 42.

[0024] The above example relates to the case of the insertion portion 18a formed by the fabric extension of the central portion 10. However, the present invention is also applicable to the case where the central portion itself is located between two open and unconnected portions so as to provide a contact surface against the second belt texture. Such an example will be described in relation to FIGS. 5 and 6A to 6C.

[0025] FIG. 5 is a cross-sectional view of a first texture 100 of a modified embodiment, the first texture 100 having, over all or part of its length, two positioning edges 120 with non-connected lateral portions 160a, 160b separated by non-connected regions 140 that enable the separation of these portions 160a, 160b from each other on both its sides 111, and a central portion 110 therebetween. As in the previous example, the positioning edges 120 and the central portion 110 are offset along the width direction L, and the non-connected portions 160a, 160b are offset along the thickness direction E. The first texture 100 comprises, for example, woven skins 102a, 102b obtained by three-dimensional weaving, which form segments of the central portion 110 and extend into extensions of this portion so as to form the non-connected portions 160a, 160b. The skins 102a, 102b are formed by weaving between first yarns C1 to C4 and C13 to C16 extending along the longitudinal direction X together with second yarns t1 to t8 extending along the direction L. In general, it will be appreciated that the number of layers of yarns shown as well as the weaving pattern are provided only by way of example and can be changed without departing from the scope of the present invention. The central portion 110 also comprises a set 102c of non-woven yarns C5 to C12 located between and held together by the yarns coming from the skins 102a, 102b. In fact, it should be noted that the yarn t4 extends into the first skin 102a outside the central portion 110 and is deflected to come out of this first skin 102a and join the set 102c of yarns C5 to C12 in the central portion 110. Similarly, the yarn t5 extends into the second skin 102b outside the central portion 110 and is deflected to come out of this second skin 102b and join the set 102c of yarns C5 to C12 in the central portion 110 on the side opposite to the yarn t4. The encapsulation of the set 102c of non-woven yarns C5 to C12 is obtained between the skins 102a, 102b, and these yarns C5 to C12 are held in place by the deflected yarns t4 to t5. In the example shown, along the thickness direction E, continuously, there are the first skin 102a, the set 102c of non-woven yarns, and the second skin 102b in the central portion 110. It should be noted that the set 102c of non-woven yarns is present only in the central portion 110 and not in the positioning edges 120.The yarns C5 to C12 can be made of non-woven fabric only over a part of the length of the first texture 100, for example over its intermediate region ZM, but it should also be noted that they can be made of woven fabric over the longitudinal ends of the first texture 100. The length when the yarns C5 to C12 are non-woven fabric can be 50% or more of the length of the first texture 100. FIGS. 6A to 6C show, in a simplified form, the shaping of the first texture of FIG. 5 and the positioning of the second belt texture 40, and this configuration is understood to be symmetric with respect to the directions L and E. In the example considered, openings of the non-articulated joints 160a, 160b are provided in the shape (not shown) so as to form an angle of substantially 90° with respect to the direction L and to position the non-articulated joints 160a, 160b at the height of the non-woven yarn set 102c. This height is taken along the direction L. This gives a positioning surface 130 of substantially flat shape, at the same level, having the non-connected parts 160a, 160b, and the yarn set 102c of the central part 110 which is located between these non-connected parts and thus defines a contact surface for the belt texture 40. FIG. 5 is a cross-sectional view of the first texture 100 of a modified embodiment, having two positioning edges 120 on both sides 111 thereof, each having non-connected lateral parts 160a, 160b separated by non-connected regions 140 that allow separation of these parts 160a, 160b from each other over all or part of its length. As in the previous example, the positioning edges 120 and the central part 110 are offset along the width direction L, and the non-connected parts 160a, 160b are offset along the thickness direction E. The first texture 100 comprises, for example, fabric skins 102a, 102b obtained by three-dimensional weaving, which form segments of the central part 110 and extend to the extensions of this part so as to form the non-connected parts 160a, 160b. The skins 102a, 102b are formed by weaving between the second yarns t1 to t8 extending along the direction L and the first yarns C1 to C4 and C13 to C16 extending along the longitudinal direction X. In general, it will be recognized that the number of yarn layers shown as well as the weaving pattern are provided only by way of example and can be changed without departing from the scope of the present invention.The central portion 110 also includes a set 102c of non-woven yarns C5 to C12 that is located between the outer skins 102a, 102b and is held together by the yarns coming from there. In fact, it should be noted that the yarn t4 extends into the first outer skin 102a outside the central portion 110 and is deflected out of this first outer skin 102a to join the set 102c of yarns C5 to C12 in the central portion 110. Similarly, the yarn t5 extends into the second outer skin 102b outside the central portion 110 and is deflected out of this second outer skin 102b to join the set 102c of yarns C5 to C12 in the central portion 110 on the side opposite to the yarn t4. The encapsulation of the set 102c of non-woven yarns C5 to C12 is obtained between the outer skins 102a, 102b, and these yarns C5 to C12 are held in place by the deflected yarns t4 to t5. In the example shown, in the central portion 110, along the thickness direction E, the first outer skin 102a, the set 102c of non-woven yarns, and the second outer skin 102b are continuously present. It should be noted that the set 102c of non-woven yarns is present only in the central portion 110 and not in the positioning edge portion 120. The yarns C5 to C12 can be made into a non-woven fabric over only a part of the length of the first texture 100, for example, over its middle region ZM, but it should also be noted that they can be made into a woven fabric over the longitudinal ends of the first texture 100. When the yarns C5 to C12 are non-woven fabrics, the length can be 50% or more of the length of the first texture 100. FIGS. 6A to 6C show, in a simplified form, the shaping of the first texture of FIG. 5 and the positioning of the second belt texture 40, and this configuration is understood to be symmetric with respect to the directions L and E. In the example considered, there are openings of the non-articulated joints 160a, 160b so as to form an angle of substantially 90° with respect to the direction L in terms of shape (not shown), and also to position the non-articulated joints 160a, 160b at the height of the set 102c of non-woven yarns. This height is taken along the direction L. This gives a positioning surface 130 of substantially flat shape and, at the same level, has the set 102c of yarns in the central portion 110 that is located between the non-connected portions 160a, 160b and thus defines a contact surface for the belt texture 40.

Claims

1. A method for manufacturing a fibrous preform for a composite component intended to be articulated with other components, The aforementioned method, The first fibrous core texture (1;100) is formed by weaving an extended shape that extends in the longitudinal direction (X), wherein the first fibrous core texture (1;100) has a central portion (10;110) on both sides (11;111) having two positioning edges (12;120) each having two unconnected transverse fiber portions (16a;16b;160a;160b), and Forming a first fiber texture, comprising opening at least unconnected lateral portions in order to form a positioning surface (30; 130) defined by a plurality of open lateral portions, or defined by an extension of the central portion (18a) and the central portion (110), and located between the plurality of open lateral portions. A method for positioning a second woven belt fiber texture (40) across a plurality of open transverse portions and insert fiber portions, wherein the second woven belt fiber texture forms loops around the molded first fiber texture at the longitudinal end between the first fiber texture and the second woven belt fiber texture, such that it defines an empty space (42) intended for articulation to other parts.

2. The method according to claim 1, wherein each positioning edge (12) further comprises an insert fiber texture (18) that extends from the central portion (10) and is located between the two unconnected transverse fiber portions (16a; 16b), and further comprises cutting the insert fiber texture such that forming the first fiber texture forms the insert fiber portion (18a).

3. The method according to claim 1, wherein the central portion (110) comprises a plurality of fabric layers (102a; 102b) and a pair of nonwoven yarns (102c) located between the plurality of fabric layers and held together by yarns (t4; t5) coming therefrom, the plurality of fabric layers extend beyond the central portion into the positioning edge (120) to form the unconnected transverse fiber portions (160a; 160b), and these unconnected portions are opened up to fold up to the height of the pair of nonwoven yarns during molding.

4. The method according to claim 1, wherein the two unconnected transverse fiber portions (16a; 16b; 160a; 160b) are formed by weaving a first yarn and a second yarn, having a first volume ratio of the first yarn to the second yarn, and the second woven belt fiber texture (40) is formed by weaving the first yarn and the second yarn, having a second volume ratio of the first yarn to the second yarn, and the relative difference between the first volume ratio and the second volume ratio does not exceed 25%.

5. The method according to claim 1, wherein the first fiber texture (1; 100) and the second woven belt fiber texture (40) are made from carbon yarn.

6. In a method for manufacturing composite material parts intended to be articulated with other parts, The aforementioned method, To form a fibrous preform for a component obtained by carrying out the method of claim 1, A method comprising forming a matrix in the porosity of the fibrous preform thus obtained.

7. The method according to claim 6, wherein the matrix is ​​organic.

8. The method according to claim 6 or 7, wherein the component is a landing gear strut, a segment of a landing gear strut, or a brake bar.

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