Fibrous reinforcement for producing composite component to be hinged to other components

Abstract

The invention relates to a fibrous preform for the core of a fibrous reinforcement of a composite component, the preform having an elongated shape in a longitudinal direction (X) and being formed from a first yarn (C1-C16) extending in the longitudinal direction and a second yarn (t1-t8) transverse to the first yarn, the preform comprises two longitudinal ends for articulating with other components and an intermediate region located between the longitudinal ends, each longitudinal end having a thickness greater than the thickness of the intermediate region, the intermediate region comprising a reinforcing section (102c) comprising first non-woven yarns (C5-C12), the first non-woven yarns (C5-C12) being interwoven with the first non-woven yarns (C5-C12), and the second non-woven yarns (C5-C12) being interwoven with the first non-woven yarns (C5-C12). And each longitudinal end comprises a three-dimensional weaving of the first yarn and the second yarn of the reinforcing section.

Description

Technical Field

[0001] The invention relates to a fiber preform for forming part of a fiber reinforcement of a component made of composite material, the component being intended to be articulated at its ends to other components, and to a related method of manufacturing. Background Art

[0002] In order to reduce weight, it is proposed to use composite materials instead of metal materials, which has always been a concern in the specific case of aircraft components. From this point of view, document US 7 704 429 proposes to manufacture a landing gear strut in composite materials, which includes areas called forks, which are used for articulation and introduction of stresses with other parts and are formed by a laminated structure in which interlayers are inserted between the main layers, extending the body of reinforcing material. However, this solution may have disadvantages. In fact, to avoid the risk of delamination, forks with a laminated configuration can lead to an increase in the size of the stress introduction area compared to metal parts. Due to the increased volume, the weight saving of the entire system becomes less attractive and the integration of the components is more limited. Another problem is that the manufacturing technology proposed involves a lot of manual intervention, which can lead to non-compliance / inconsistency and increased costs. Finally, the mechanical properties of the composite material proposed in this document can be improved, especially in terms of compressive strength in the middle area of ​​the length of the part, called the common area. One option to solve this problem is to add material in the common area, but this sacrifices quality and is therefore not completely satisfactory.

[0003] The present invention aims to solve all or part of the above-mentioned disadvantages. Summary of the invention

[0004] The present invention relates to a fiber preform for a core of a fiber reinforced component of a composite material component, the preform having an elongated shape along a longitudinal direction and being formed by a first yarn extending along the longitudinal direction and a second yarn transverse to the first yarn, the preform comprising two longitudinal ends for being hinged together with other components and a middle region between the longitudinal ends, the thickness of each longitudinal end being greater than the thickness of the middle region, the middle region comprising a reinforcement section composed of a first non-woven yarn, and each longitudinal end comprising three-dimensional weaving of the first yarn and the second yarn of the reinforcement section.

[0005] The invention proposes an optimized design of a core preform of a core-belt assembly type fiber reinforcement, which is based on three-dimensional weaving technology and an articulated area with increased thickness compared to the middle area or common area, so as to obtain an increased tolerance for stress introduction areas. The reinforcing section can significantly improve the compression performance of the middle area compared to the structure obtained entirely by three-dimensional weaving. The invention also limits or even avoids weaving with the second yarn in the middle area, which reduces material consumption and processing (such as cutting) after the weaving operation. The first yarn of the reinforcing section is woven at the longitudinal end by three-dimensional weaving in order to obtain the required stress resistance / tolerance in the articulated area.

[0006] In one exemplary embodiment, the fiber preform comprises a braided sheath on both sides of a reinforcement section, wherein a first yarn of the reinforcement section is held / fixed by yarns from the braided sheath.

[0007] This feature is beneficial to improving the impact resistance of the fiber reinforcement.

[0008] In particular, the woven skin can comprise folded, non-interconnected transverse fiber sections which form positioning surfaces for the fiber tape structure on the upper and lower sides of the preform.

[0009] This feature helps improve the quality of the interface between the core and the strip, further improving the mechanical properties of the component.

[0010] In an exemplary embodiment, the preform further comprises a transition zone between each longitudinal end and the middle zone, the transition zone comprising, compared to the middle zone, a further layer of first yarns, which are woven with the second yarns in the longitudinal ends.

[0011] This feature is conducive to further increasing the thickness of the longitudinal end portion, thereby further improving the mechanical properties of the component.

[0012] In one exemplary embodiment, the preform is made of carbon yarn.

[0013] The invention also relates to a method for producing a fiber reinforcement of a composite material component, comprising: - Positioning a woven fabric tape structure on the core preform as described above, said tape structure defining a loop around the core preform so as to define at the longitudinal ends free spaces for articulation with other components.

[0014] In one exemplary embodiment, the tape structure is made of carbon yarn.

[0015] The invention also relates to a method for manufacturing a composite component intended to be articulated with other components, the method comprising: - forming a fiber reinforcement as described above, and - Formation of a matrix in the pores of the fiber reinforcement thus obtained.

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

[0017] In an exemplary embodiment, the component is a landing gear strut, a portion of a landing gear strut, or a brake rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [ Figure 1 ] Figure 1 An example of a fiber structure intended to form a preform according to the invention is schematically shown.

[0019] [ Figure 2 ] Figure 2 Schematically shows Figure 1 cross section of the structure.

[0020] [ Figure 3A ] Figure 3A Schematically and partially shows the Figure 1 and 2 A possible first step in the shaping of the structure.

[0021] [ Figure 3B ] Figure 3B Schematically and partially shows the Figure 1 and 2 A second step of possible shaping of the structure.

[0022] [ Figure 3C ] Figure 3C Schematically and partially shows the Figure 1 and 2 A third step is the possible shaping of the structure and the positioning of the belt.

[0023] [ Figure 4 ] Figure 4 is a perspective view of one example of a fiber reinforcement of the core-tape assembly type according to the present invention. DETAILED DESCRIPTION

[0024] Figure 1 A woven fiber structure 100 is shown which is intended to form a fiber preform 200 after shaping (see Figure 3B , 3C and 4), the fiber preform 200 is the core of the fiber reinforcement for the composite material component. Figures 3A to 3CA possible shaping of the structure is described. The structure 100 and the preform 200 have an elongated shape extending along the longitudinal direction X and can be obtained by weaving into a single component. The structure 100 and the preform 200 successively include a first longitudinal end 103a, a middle zone ZM and a second longitudinal end 103b along the direction X. In the illustrated example, there is also a first transition zone ZTa between the first end 103a and the middle zone ZM, and there is also a second transition zone ZTb between the middle zone ZM and the second end 103b. The presence of transition zones ZTa and ZTb is considered in the illustrated example, but within the framework of the present invention, the transition zone ZTa remains optional. According to an example, the length La, Lb of each transition zone ZTa, ZTb that may exist may be between 1% and 20% of the length LO of the structure 100 or the preform 200, and the length L2, L3 of each end 103a, 103b may be between 1% and 20% of the length LO. The length is measured along the direction X. The middle zone ZM may be centered relative to a plane P50 located at the middle of the length of the structure 100 or preform 200 and perpendicular to the direction X. Figure 1 In the example shown, the thickness e2 of the first end 103a is greater than the thickness e1 of the middle zone 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 (direction E) and corresponds to the minimum dimension. In one example, the ratio e2 / e1 can be greater than 1 and less than or equal to 4, for example, between 1.5 and 2.5, and the ratio e3 / e1 can be greater than 1 and less than or equal to 4, for example, between 1.5 and 2.5.

[0025] The textile structure between the end portions 103a, 103b, the transition zones ZTa, ZTb and the middle zone ZM is different, as will be described in detail below. The end portions 103a, 103b are obtained by three-dimensionally weaving a first yarn extending in the direction X with a second yarn transverse to the first yarn, for example, using an "interlocking" weaving pattern. In the illustrated example, a portion of the first yarn present in the end portions 103a, 103b forms a reinforcement section 102c in the middle zone ZM and is not woven with the second yarn in the section 102c. The first yarn may extend in a substantially straight line in the reinforcement section 102c. The reinforcement section 102c may include a unidirectional layer of the first yarn. In general, the number of the first non-woven yarn in the middle zone ZM may account for the majority (more than 50%), for example, at least 80% of the number of all yarns present in the middle zone ZM. A second yarn is added in the longitudinal end portions 103a, 103b so as to weave / interweave the first yarn of the reinforcement section 102c. These added second yarns correspond to an additional yarn layer compared to the second yarn layer that may be present in the middle zone ZM. Figure 2A possible textile configuration at the middle zone ZM is shown (cross-sectional view relative to the direction X). The structure 100 comprises a central section 110 having two positioning edges 120 on opposite sides 111, each of which comprises non-interconnected side sections 160a, 160b separated by a non-interconnected area 140, thereby allowing these sections 160a, 160b to be spaced relative to each other. The positioning edges 120 and the central section 110 are offset in the width direction L, and the non-interconnected sections 160a, 160b are offset in the thickness direction E. The central section 110 comprises a reinforcement section 102c, which comprises first non-woven yarns C5-C12. A braided sheath 102a, 102b, obtained, for example, by three-dimensional braiding (for example by "interlocking" braiding), is present in the central section 110 and extends beyond it, forming non-interconnected sections 160a, 160b. The sheath 102a, 102b is formed by braiding between first yarns C1-C4 and C13-C16 extending in the longitudinal direction X and second yarns t1-t8 extending in the direction L. In general, it should be recognized that the number of yarn layers and the braiding pattern shown are provided only by way of example and can be modified without departing from the scope of the invention. The sheaths 102a, 102b are located in the middle zone ZM and they extend to the ends 103a, 103b, defining a single piece of fabric that extends over the entire width and thickness of the structure 100 or preform 200. The yarns C5-C12 of the reinforcement section 102c are located between the sheaths 102a, 102b and are fixed together by the yarns from the sheaths 102a, 102b. In fact, it is worth noting that the yarn t4 extends outside the central section 110 in the first sheath 102a and is deflected so as to come out / expose from the first sheath 102a, thereby binding / fixing the group 102c of the yarns C5-C12 in the central section 110. Similarly, on the side opposite to the yarn t4, the yarn t5 extends outside the central section 110 in the second sheath 102b and is deflected so as to come out / expose from the second sheath 102b, thereby binding / fixing the group 102c of the yarns C5-C12 in the central section 110. Thus, the encapsulation of the reinforcement section 102c (which is formed by the yarns C5-C12) between the skins 102a, 102b is achieved, these yarns C5-C12 being fixed in place by the deflected yarns t4-t5. In the illustrated example, in the central section 110, in the thickness direction E, there are: the first skin 102a, the section 102c formed by the unwoven yarns, and the second skin 102b. It should be noted that the section 102c formed by the unwoven yarns is present only in the central section 110, and not in the positioning edge 120. This allows saving yarn in this area and avoids manual cutting steps (if these yarns are woven).As described above, the yarns C5-C12 are not only woven over a portion of the length of the first structure 100 or preform 200, woven over its middle zone ZM and possibly woven over transition zones ZTa, ZTb, but also woven into the longitudinal ends 103a, 103b. The length of the non-woven yarns C5-C12 may be greater than or equal to 50%, for example 75%, of the length LO of the structure 100 or preform 200.

[0026] Figures 3A to 3C Shown in a simplified manner Figure 1 and 2 The shaping of the structure 100 in order to obtain the preform 200 and the positioning of the second belt structure 40, it being understood that this configuration is symmetrical with respect to the directions L and E. In the example considered, the non-interconnected sectors 160a, 160b are developed in a profile (not shown) so as to form an angle of substantially 90° with the direction L and to position the non-interconnected sectors 160a, 160b at the height of the sector 102c. The height is measured along the direction L. A preform 200 is thus obtained, which has a positioning surface 130 of substantially flat shape, with the non-interconnected sectors 160a, 160b and the sector 102c located between these non-interconnected sectors at the same height, thereby defining a load-bearing surface for the belt structure 40. Relative to the longitudinal direction X, the cross-section of the preform 200 may have an I-shape (called a diptych). In Figure 1 In the example of , there is a transition zone ZTa, ZTb between the middle zone ZM and the end portions 103a, 103b. The reinforcement section 102c is also present in the transition zone ZTa, ZTb, but the outer skin 104a1, 104a2, 104b1 and 104b2 is thickened relative to the outer skin 102a, 102b of the middle zone ZM. In fact, an additional first yarn layer is added to this region relative to the yarn present in the middle zone ZM. As shown in the figure, the first yarn layer added in this region can be gradually woven with the second yarn to form the outer skin 104a1, 104a2, 104b1 and 104b2, and extend into the end portions 103a, 103b, so as to obtain the thickness required for the latter when a significant increase in thickness is required.

[0027] Figure 4An example of a core tape assembly according to the invention is shown, which forms a fiber reinforcement 300 of the component to be obtained. A woven tape structure 40 has been positioned around a preform 200 obtained after shaping the structure 100 by folding down the non-interconnected sections 160a, 160b. The structure 40 may have the shape of a strip wound around the preform 1. When it is positioned, the structure 40 bears / rests on the positioning surface 130. The structure 40 may be in the form of a single fabric strip, but it does not go beyond the scope of the invention if it is in the form of a plurality of strips connected end to end or placed side by side. The structure 40 may also be obtained by three-dimensional weaving, for example using an "interlocking" weaving pattern. The structure 40 defines a closed loop around the preform 200 and defines a free space 42 for articulation with other components. Inserts (not shown) may be temporarily used at the longitudinal ends 103a, 103b, and a second structure 40 may be wound around them to ensure that the end region has the desired shape. As shown, the ends 103a, 103b may have a curved shape, for example a substantially circular shape. The transverse dimension DT of the positioning surface 130 increases from the first end 103a towards the middle zone ZM, is maximum near the mid-length plane P50 of the preform 200, for example at least in the section between the planes P40 and P60 - the planes P40 and P60 are located at 40% and 60% of the length LO and are perpendicular to the direction X, and then decreases towards the second end 103b. The positioning surface 130 defines a side fin for positioning the belt structure 40. The volume ratios between the warp and weft yarns of each preform 200 and the belt structure 40 may be similar, for example differing by up to 10%. For each textile considered, these volume ratios correspond to the following ratios: [volume occupied by the warp yarns] / [volume occupied by the weft yarns].

[0028] The entire preform 200 and structure 40 are then densified, for example by introducing a resin (for example an epoxy resin) and then crosslinking if the resin is a thermosetting resin or cooling if the resin is a thermoplastic resin. The formation of the matrix can be carried out by a resin transfer molding technique, which is a technique known per se. In this way, a composite component is obtained, which is intended to be hinged to other components at its longitudinal ends and to withstand tensile and compressive stresses. The fiber reinforcement of the component can be formed by carbon yarn and the component can have the organic matrix just described. The component can be used or not for aviation applications. The component can be, for example, a connecting rod, a landing gear strut or a component thereof, or a brake rod. The component obtained can be mounted on other components by positioning a hinge pin for connection to other components and a contact insert with the pin in the free space 42.

Claims

1. A method for manufacturing a fiber reinforcement (300) for a composite material component, comprising: - positioning a woven fiber tape structure (40) on a fiber preform (200) for a core of a fiber reinforcement (300) for a composite component, the preform having an elongated shape in a longitudinal direction (X) and formed by first yarns (C1-C16) extending in the longitudinal direction and second yarns (t1-t8) transverse to the first yarns, The preform comprises two longitudinal ends (103a; 103b), and a middle area (ZM) located between the longitudinal ends, the thickness (e2; e3) of each longitudinal end is greater than the thickness (e1) of the middle area, the middle area includes a reinforcement section (102c), the reinforcement section includes a first non-woven yarn (C5-C12), and each longitudinal end includes a three-dimensional weaving of the first yarn and the second yarn of the reinforcement section, the belt structure defines a loop of the preform around the core so as to define a free space (42) at the longitudinal end for hinged connection with other parts.

2. The method according to claim 1, wherein: The fiber preform comprises a braided sheath (102a; 102b) on both sides of the reinforcement section (102c), wherein the first yarns (C5-C12) of the reinforcement section are retained by yarns (t4; t5) from the braided sheath.

3. The method according to claim 2, wherein: The woven outer skin (102a; 102b) comprises folded, non-interconnected transverse fiber sections (160a; 160b) which form positioning surfaces (130) for a fiber tape structure (40) on the upper and lower sides (111) of the preform.

4. The method according to any one of claims 1 to 3, wherein: The preform further comprises a plurality of longitudinal ends (103a; 103b) and a middle zone (ZM), said transition zone comprising a further layer of first yarns, woven together with the second yarns in said longitudinal end portions, compared to the yarns present in said middle zone.

5. The method according to any one of claims 1 to 4, wherein: The preform is made of carbon yarn.

6. The method according to any one of claims 1 to 5, wherein: The belt structure (40) is made of carbon yarn.

7. A method for manufacturing a composite component intended to be articulated with other components, comprising: - forming a fiber reinforcement (300) according to any one of claims 1 to 6, and - Formation of a matrix in the pores of the fiber reinforcement thus obtained.

8. The method according to claim 7, wherein: The matrix is ​​an organic matrix.

9. A method according to claim 7 or 8, wherein The component is a landing gear strut, a portion of a landing gear strut or a brake rod.

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