Curved stiffeners for a nacelle of a turbine engine and method for producing such stiffeners

Abstract

The invention relates to a curved reinforcement (10) for a turbine engine casing, the curved reinforcement (10) being formed from a resin-impregnated fibre reinforcement comprising: a stack of a plurality of fibre layers stacked along a thickness direction and extending over an entire width of the fibre reinforcement, each fibre layer having a plurality of parallel fibres extending along a direction oblique with respect to a length direction, and fibres of two consecutive fibre layers in the thickness direction having directions oblique with respect to each other, and wherein the individual fibre layers are stitched together by stitching threads extending along the length direction, the fibre reinforcement comprising a reinforcement fibre layer having a plurality of parallel fibres extending along the length direction, the reinforcement fibre layer extending over a width, at least over a central portion, which is smaller than the width of the fibre reinforcement. The invention also relates to a method for producing the reinforcement (10).

Description

Technical Field

[0001] This disclosure relates to a bending reinforcement for a turbine engine nacelle, and more particularly to a bending reinforcement made of a resin-impregnated fiber reinforcement. This disclosure also relates to a method for manufacturing such a reinforcement. Background Technology

[0002] The nacelle is typically provided to house a bypass turbojet engine, which generates, on the one hand, a hot airflow (also known as the main flow) from the turbojet engine's gas generator, and on the other hand, generates a cool airflow (also known as the secondary flow) from the fan and circulates outside the turbojet engine through an annular channel, usually referred to as the secondary flow path. Both airflows are expelled from the turbojet engine through the rear of the nacelle.

[0003] To maintain the nacelle's structure, one or more generally circumferentially curved reinforcements can be provided to strengthen its structure. Such composite reinforcements, comprising multi-oriented fiber reinforcements and consisting of a number of unidirectional fiber layers assembled by seams across the thickness, are known as NCF (non-crimped fabric). This type of reinforcement comprises multiple layers of parallel fibers, each layer having fibers oriented according to the orientation of the fibers in its adjacent layers. This type of reinforcement is obtained by flat-sewing multiple layers of fibers together, laying the reinforcement on a reinforcement mold, impregnating it with resin, and then cross-linking the resin impregnated in the fibers.

[0004] However, this type of reinforcement cannot include a fiber layer oriented along the length of the reinforcement. In fact, the curvature of the reinforcement creates a difference in length between its head and foot, but the fibers typically used in manufacturing composite reinforcements do not have sufficient elongation to absorb this difference. Therefore, the presence of a fiber layer along the length of the reinforcement introduces defects during the process of laying the fiber reinforcement onto the mold forming the reinforcement, such as creases appearing in the fiber layer.

[0005] As a result, this type of reinforcement exhibits lower drag. In fact, the effect of undulations on the structural strength of the reinforcement is a particularly interesting point.

[0006] Therefore, there is indeed a need for a fabric reinforcement that meets the mechanical strength requirements and forming method of the reinforcement and can overcome the aforementioned defects. Summary of the Invention

[0007] This disclosure relates to a bending reinforcement for a turbine engine shroud, comprising a resin-impregnated fiber reinforcement. The reinforcement includes a head with an annular portion shape, two feet concentric with the head and having a radius greater than the head radius, and two inclined portions, each inclined portion connecting one of the feet to a side of the head. The fiber reinforcement extends along its length, width, and thickness directions. The dimension of the fiber reinforcement along its length is greater than its dimension along its width, and the dimension of the fiber reinforcement along its thickness is the smallest of the fiber reinforcement dimensions. The fiber reinforcement has a central portion configured to form the head, and two end portions are disposed on either side of the central portion and configured to form... The central portion is connected to the end portion by two connecting portions and configured to form an inclined portion. The fiber reinforcement includes a stack of multiple fiber layers stacked along the thickness direction and extending over the entire width of the fiber reinforcement. Each fiber layer has multiple parallel fibers extending in a direction inclined relative to the length direction. The fibers of two consecutive fiber layers along the thickness direction have a direction inclined relative to each other. The individual fiber layers are sewn together by a sewing line extending along the length direction. The fiber reinforcement includes a reinforcing fiber layer sewn to the fiber layers by a sewing line having multiple parallel fibers extending along the length direction. The reinforcing fiber layer extends at least in the central portion over a width smaller than the width of the fiber reinforcement.

[0008] In this disclosure, it should be understood that the dimension of the fiber reinforcement along the thickness direction is much smaller than the dimension of the fiber reinforcement along the length and width directions.

[0009] In some non-limiting examples, when the reinforcement is placed in a turbine engine nacelle, the thickness direction corresponds to the radial direction of the nacelle, the length direction corresponds to the circumferential direction of the nacelle, and the width direction corresponds to the axial direction of the nacelle. In these examples, it should be understood that in a given plane perpendicular to the axial direction of the nacelle and passing through the reinforcement, the head of the annular portion shape is concentric with the feet of the two annular portions, and the radius of the head is smaller than the radius of the feet. However, other configurations are contemplated, in which the length direction, when the reinforcement is placed in the nacelle, will correspond to, for example, the axial direction or an intermediate direction between the axial and circumferential directions. Furthermore, the reinforcement of the present invention can be used in components other than turbine engine nacelles.

[0010] The drag and stiffness of a reinforcement member that includes a layer of reinforcing fibers oriented along its length (in other words, at 0 degrees relative to the length direction). In fact, the presence of the reinforcing fibers allows for better resistance to the stresses the reinforcement member may experience, especially when the layer is located at the level of the reinforcement member's head. For example, this reinforcement allows the nacelle to more easily withstand compressive and tensile stresses along the radial direction.

[0011] Furthermore, the configuration of this embodiment allows for the inclusion of longitudinal reinforcing fiber layers of the fiber reinforcement, and thus longitudinal reinforcing fiber layers of the reinforcement, without defects occurring during layup. This appearance is ensured by the fact that the reinforcing fiber layers extend over a width smaller than that of the reinforcement.

[0012] This solution allows for the production of reinforcements with excellent performance, where the fiber reinforcement can be fully laid in a single layup step. In fact, the reinforcing fiber layer can be sewn together with other fiber layers in a single sewing step. Therefore, to obtain a functional reinforcement, it appears unnecessary to plan the reinforcing fiber reinforcement step before or after layup.

[0013] In some embodiments, the reinforcing fiber layer extends over a portion of the connection portion.

[0014] In this configuration, the fibers protruding from the reinforcing fiber layer at the connecting portion will promote the centering of the fiber reinforcement during the application of the fiber reinforcement to the reinforcing die. In fact, once placed on the die, these fibers protruding from the connecting portion will exhibit slightly higher tension than the fibers placed on the central portion. In this way, the fiber reinforcement will be positioned such that the fibers protruding from the connecting portion on both sides of the central portion are evenly distributed. Therefore, the fiber reinforcement is more easily centered in the reinforcing die.

[0015] In some embodiments, reinforcing fiber layers are disposed on a plurality of fiber layers at one end of the fiber reinforcement along the thickness direction.

[0016] This configuration is advantageous for the manufacture of fiber-reinforced components.

[0017] In some embodiments, the reinforcement includes at least one additional reinforcing fiber layer disposed in a stack of fiber layers.

[0018] In this configuration, the stiffness of the reinforcement is increased. The stiffness of the reinforcement can then be controlled based on the number of additional reinforcing fiber layers included in the stack of fiber layers.

[0019] In some embodiments, the reinforcement includes a chain stitch seam disposed at the end of the fiber reinforcement along the width direction.

[0020] This configuration facilitates the cutting of fiber reinforcements mounted on the reinforcing mold.

[0021] In some embodiments, the fiber layer and the reinforcing fiber layer are sewn together by a knitted stitch.

[0022] The use of knitted stitches enhances the deformability of fiber reinforcements.

[0023] In some embodiments, the tension of the sewing thread in the connecting portion is lower than the tension of the sewing thread in the central portion.

[0024] In this configuration, the connecting portions of the fiber reinforcements are able to withstand greater deformation than the central portions of the fiber reinforcements. In particular, this configuration facilitates the layup of the fiber reinforcements while limiting defects that may occur during layup.

[0025] In some embodiments, the stitches are more densely distributed in the central portion than in the connecting portion.

[0026] In this configuration, the reinforcing fiber layer is sewn together with other fiber layers in a more robust manner, which contributes to the stability of the fiber reinforcement.

[0027] In some embodiments, the stitching thread sewn on the end portions and connecting portions has excess length.

[0028] In this configuration, the excess length of the stitching allows for easier deformation of the end portions and connecting parts. Therefore, it is advantageous to lay the fiber reinforcement onto the reinforcing mold.

[0029] This disclosure also relates to a nacelle including the reinforcements defined above.

[0030] This disclosure also relates to an aircraft engine that includes a nacelle as defined above.

[0031] Nacelles and aircraft engines have the advantages disclosed above.

[0032] This disclosure also relates to a method for manufacturing a bending stiffener as defined above, comprising:

[0033] The steps include a sewing step, wherein a fiber reinforcement is formed by sewing together multiple fiber layers and (multiple) reinforcing fiber layers; a laying step, wherein the fiber reinforcement is placed on a reinforcement mold; an impregnation step, wherein the fiber reinforcement placed on the reinforcement mold is impregnated with resin; and a polymerization step, wherein the resin impregnated in the fiber reinforcement is cured.

[0034] This method makes it possible to obtain reinforcements that have the aforementioned advantages.

[0035] The foregoing features and advantages, as well as other features and advantages, will become apparent from the following detailed description of exemplary embodiments of the proposed device and method. This detailed description refers to the accompanying drawings. Attached Figure Description

[0036] The accompanying drawings are schematic and are primarily intended to illustrate the principles of this disclosure.

[0037] [ Figure 1A ] Figure 1A This refers to a bending reinforcement according to a first embodiment of the bending reinforcement.

[0038] [ Figure 1B ] Figure 1B This refers to a bending reinforcement according to a second embodiment of the bending reinforcement.

[0039] [ Figure 1C ] Figure 1C This refers to a bending reinforcement according to a third embodiment of the bending reinforcement.

[0040] [ Figure 2 ] Figure 2 This is a partial view of the fiber reinforcement according to the first embodiment during the sewing step.

[0041] [ Figure 3 ] Figure 3 This is a partial view of the fiber reinforcement according to the second embodiment.

[0042] [ Figures 4A-4B ] Figure 4A and Figure 4B This refers to the molds for fiber reinforcement and strengthening components at different lay-up times.

[0043] [ Figure 5 ] Figure 5 The stitching of the fiber reinforcement is shown schematically.

[0044] [ Figure 6 ] Figure 6 Schematic representation of the formation Figure 2 The steps of the method for strengthening components.

[0045] [ Figure 7 ] Figure 7 The illustration schematically depicts an aircraft engine including a nacelle, which incorporates reinforcements according to an embodiment. Detailed Implementation

[0046] To make this disclosure more concrete, examples of the device are described in detail below with reference to the accompanying drawings. It should be understood that the invention is not limited to these examples.

[0047] Figure 7An aircraft engine 1000 including a nacelle 100 is schematically shown. The nacelle 100 includes a canopy that includes a bending reinforcement 10 according to a first embodiment of the invention.

[0048] Figure 1A This illustrates a bending reinforcement 10 according to a first embodiment of the invention. The reinforcement 10 comprises a resin-impregnated fiber reinforcement 20 and includes a head 12 with an annular portion of radius R0, two feet 16 with an annular portion of radius R1 concentric with the head 12, and two inclined portions 14, each inclined portion 14 connecting one of the feet 16 to a side of the head 12. Furthermore, when the nacelle 100 has a circular cross-section, the radius R1 of the two feet 16 is greater than the radius R0 of the head 12. Therefore, the reinforcement 10 extends at an angle α (alpha) of the measured arc. This shape of the reinforcement 10 is referred to as an omega shape. Specifically, the head 12 and the inclined portions 14 are observed to have trapezoidal shapes independently. In some examples, the angle α can extend to 360 degrees.

[0049] Figure 2 This is a partial view of the fiber reinforcement 20 according to the first embodiment. The fiber reinforcement 20 extends along its length, width, and thickness directions. When the fiber reinforcement 20 is placed on a flat surface, these three directions define an orthogonal reference system.

[0050] The fiber reinforcement 20 has a larger dimension along its length direction than its width direction, and its dimension along its thickness direction is the smallest of its dimensions. It should be understood that the thickness direction dimension of the fiber reinforcement 20 is negligible compared to its other two dimensions. In other words, the fiber reinforcement 20 extends primarily in two dimensions.

[0051] Furthermore, once the reinforcement is installed in the turbine engine nacelle, the thickness direction corresponds to the radial direction of the turbine engine, the length direction corresponds to the circumferential direction of the nacelle, and the width direction corresponds to the axial direction of the nacelle.

[0052] The fiber reinforcement 20 defines a central portion configured to form a head 12 of the manufactured reinforcement. It also defines two end portions disposed on both sides of the central portion configured to form feet 16, and two connecting portions connecting the central portion to the end portions and configured to form inclined portions 14.

[0053] like Figure 2As indicated, the fiber reinforcement 20 comprises a stack of multiple fiber layers 22 stacked along the thickness direction. Each fiber layer 22 extends over the entire width of the fiber reinforcement 20. Furthermore, each fiber layer 22 consists of multiple fibers parallel to each other. The fibers of the fiber layer 22 extending in a direction inclined relative to the length direction and the fibers of two consecutive fiber layers 22 along the thickness direction have an orientation inclined relative to each other.

[0054] In this embodiment, and in a non-limiting manner, the fibers of the continuous fiber layer 22 along the thickness direction have angles of -45° (or 135°), 90°, 45°, 270°, and 225° with respect to the length direction, respectively.

[0055] The fiber reinforcement 20 also includes a reinforcing fiber layer 24. The reinforcing fiber layer 24 is disposed on a plurality of fiber layers 22 at the ends of the fiber reinforcement 20 along the thickness direction. In other words, the reinforcing fiber layer 24 is disposed above the fiber layers 22 in the thickness direction.

[0056] The reinforcing fiber layer 24 has a plurality of parallel fibers extending along the length direction, that is, at an angle of 0° with the length direction, and the reinforcing fiber layer 24 extends at least in the central portion with a width smaller than that of the fiber reinforcement 20.

[0057] In this example, and in a non-limiting manner, the fiber reinforcement is composed of NCF (non-crimped fabric) carbon fibers. It should then be understood that the fibers of fiber layer 22 and the fibers of reinforcing fiber layer 24 are carbon fibers. However, glass fibers or hybrid fibers may also be used.

[0058] like Figure 2 As shown, all fiber layers 22 and reinforcing fiber layers 24 are sewn together by seams extending along their length. For example, these seams are knitted stitches.

[0059] In addition, Figure 2 In one embodiment, by way of non-limiting example, a chain-stitched seam is provided at the end of the fiber reinforcement 20 along the width direction. The chain-stitched seam also extends along the length direction and defines the width of the fiber reinforcement 20.

[0060] Figure 3 This is a partial view of a fiber reinforcement member according to a second embodiment. In this embodiment, the fiber reinforcement member 20 includes at least one additional reinforcing fiber layer 24' disposed within a stack of fiber layers 22. Figure 3In some embodiments, the additional reinforcing fiber layer 24' is identical to the reinforcing fiber layer 24. Therefore, it comprises a plurality of fibers oriented along the length direction and extending over the central portion of the fiber reinforcement 20. Furthermore, in some embodiments, the reinforcing layer 24 may be provided above, below, or inside the stack of fiber layers 22. Similarly, the additional reinforcing fiber layer 24' may be provided above, below, or inside the stack of fiber layers 22.

[0061] In some other examples, the additional reinforcing fiber layer 24' has different properties from the reinforcing fiber layer 24. For example, the additional reinforcing fiber layer 24' may be composed of glass fibers.

[0062] It should be understood that in this embodiment, the fiber reinforcement 20 may include a plurality of additional reinforcing fiber layers 24' to adjust the stiffness of the reinforcement according to the user's needs. Furthermore, for the same purpose, the thickness of the additional reinforcing fiber layers 24' may differ from each other and / or be different from the thickness of the reinforcing fiber layer 24. Similarly, the properties of the fibers in the additional reinforcing fiber layers 24' may differ from each other and / or be different from the properties of the reinforcing fiber layer 24.

[0063] Figure 4A and Figure 4B This refers to the fiber reinforcement 20 that is placed on the reinforcement mold 40 at different lay-up times. Figure 4A This refers to the fiber reinforcement 20 that is positioned to be laid on top of the reinforcement mold 40. Figure 4B This refers to the fiber reinforcement 20 that is laid on top of the reinforcing mold 40.

[0064] The reinforcing mold 40 has a shape similar to that of the reinforcing member and includes a head 42, a foot 46, and a connecting portion 44 that connects the foot 46 to the head 42.

[0065] The fiber reinforcement 20 is configured to mate with the mold 40, that is, to match the shape of the mold 40. More specifically, the central portion, connecting portion, and end portion of the reinforcement fiber 20 are configured to mate with the head 42, connecting portion 44, and foot 46, respectively.

[0066] The head 42 extends a width l along the width direction, while the reinforcing fiber layer 24 of the fiber reinforcement 20 extends a width L along the width direction. The width l of the head 42 is less than or equal to the width L of the reinforcing fiber layer 24. Therefore, the reinforcing fiber layer 24 extends on the head 42 and, in this non-limiting example, partially extends on the connecting portion 44.

[0067] In addition, in order to promote Figure 4A and Figure 4BAs illustrated in the diagram, the tension of the stitching in the connecting sections is lower than that in the central section. Furthermore, the stitching distribution in the central section is denser than that in the connecting sections.

[0068] In other words, the fiber reinforcement 20 is more easily deformed and more flexible at the level of the connecting and end portions than at the level of the central portion.

[0069] to this end, Figure 5 The stitching 30 of the fiber reinforcement 20 is schematically shown. The stitching 30 extends along the length direction. A regular stitch is provided, having two through portions 32 at the front and back and a stitching loop 34. The stitches are spaced apart by a pitch P along the length direction and by a gauge J along the width direction.

[0070] The length of the main thread used for the stitch (including the length of the through portion 32 and the length of the sewing loop 34) can vary depending on the tension that is expected to be applied at the level of the stitch. In particular, this length may be excess compared to the thread length of a conventional stitch. This excess length is calculated using the following formula.

[0071] [Formula 1]

[0072]

[0073] Figure 1B This refers to the reinforcing member 10' according to a second embodiment of the present invention. Features identical to those in the first embodiment are omitted.

[0074] In this embodiment, the reinforcing member 10' comprises two trapezoidal portions 101' and 102', as previously described in the first embodiment for... Figure 1A The reinforcement 10 is described in the diagram. Specifically, the trapezoid includes a small base corresponding to the head, a side corresponding to the sloping portion, and a large base.

[0075] The trapezoidal shape of portion 101' has an angle α1 between its base and its side, while the trapezoidal shape of portion 102' has an angle α2 between its base and its side. Furthermore, the width a of the head of the reinforcing member 10' in the second embodiment remains constant along its entire length.

[0076] Figure 1B The configuration allows the shape of the reinforcement 10' to be adapted to the structural and dimensional constraints that may be imposed on the nacelle 100.

[0077] Figure 1C "Represents the reinforcing member 10 according to the third embodiment. Features identical to those in the first embodiment are omitted."

[0078] In the third embodiment, the reinforcement 10" includes a head 12", a connecting portion 14", and a foot 16". In this embodiment, the foot 16" extends inward along the width direction into the reinforcement 10". In other words, the foot 16" extends below the head 12 along the thickness direction.

[0079] Figure 6 The steps of a method for forming a reinforcement according to a first embodiment are schematically illustrated. This method is also applicable to the second and third embodiments. The method for manufacturing the reinforcement sequentially includes a sewing step E1, a laying step E2, an impregnation step E3, and a polymerization step E4.

[0080] In sewing step E1, fiber layer 22 and reinforcing fiber layer 24 are sewn together to form fiber reinforcement 20. As explained above, the stitch is knitted. Furthermore, during this operation, a chain stitch type seam is sewn at the end along the width direction of the formed fiber reinforcement 20.

[0081] In the layup step E2, the fiber reinforcement 20 is laid over the reinforcement mold 40, so that the fiber reinforcement 20 takes the form of a bent reinforcement. The mold 40 can be as follows: Figure 4A The diagram shows either a male or female shape. The female reinforcing mold 40 corresponds to a mold whose shape is complementary to that of the male reinforcing mold 40. The male reinforcing mold 40 is typically convex, while the female reinforcing mold is typically concave.

[0082] In the second and third embodiments, a suitable mold is used during the laying step E2.

[0083] In impregnation step E3, the fiber reinforcement 20, which is placed on the mold 40, is impregnated with resin. This impregnation can be performed by resin infusion using a rigid mold and a flexible membrane in a low-pressure environment (pressure less than 1 bar), or by resin transfer molding (also known as RTM) using two rigid molds in an over-pressure environment (pressure greater than 1 bar). In this example, the resin has a low viscosity.

[0084] In polymerization step E4, the fiber reinforcement 20, placed in mold 40 and impregnated with resin, is polymerized in an oven. In this non-limiting example, the fiber reinforcement is held at 120°C for 5 hours.

[0085] Finally, once demolded from the reinforcing mold 40, the reinforcing part 10 is obtained.

[0086] Although the invention has been described with reference to specific exemplary embodiments, it will be apparent that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, various features of the different illustrated / mentioned embodiments may be combined in other embodiments. Therefore, the specification and drawings should be considered illustrative rather than restrictive.

[0087] It is equally evident that all features described by the reference method can be ported to the device individually or in combination, and conversely, all features described by the reference device can be ported to the method individually or in combination.

Claims

1. A bending reinforcement (10) for a turbine engine shroud, said bending reinforcement (10) comprising a resin-impregnated fiber reinforcement (20), The reinforcing member (10) includes a head (12) in the shape of an annular portion, two feet (16) in the shape of annular portions concentric with the head (12) and having a radius greater than that of the head (12), and two inclined portions (14), each inclined portion (14) connecting one of the feet (16) to the side of the head (12). The fiber reinforcement (20) extends along the length, width, and thickness directions. The dimension of the fiber reinforcement (20) along the length direction is greater than the dimension of the fiber reinforcement (20) along the width direction, and the dimension of the fiber reinforcement (20) along the thickness direction is the smallest dimension of the fiber reinforcement (20). The fiber reinforcement (20) has a central portion configured to form the head (12). Two end portions are placed on either side of the central portion and configured to form feet (16). The two connecting parts connect the central part to the end part and are configured to form an inclined part (14). The fiber reinforcement (20) comprises a stack of multiple fiber layers (22) stacked along the thickness direction and extending over the entire width of the fiber reinforcement (20). Each fiber layer (22) has a plurality of parallel fibers extending in a direction inclined relative to the length direction. The fibers of two consecutive fiber layers (22) along the thickness direction have an orientation that is relatively inclined to each other, and The fiber layers (22) are sewn together by stitches extending along their length. The fiber reinforcement (20) includes a reinforcing fiber layer (24) sewn to the fiber layer (22) by a stitch having a plurality of parallel fibers extending along the length direction, the reinforcing fiber layer (24) extending at least in the central portion in a width smaller than the width of the fiber reinforcement (20).

2. The reinforcing member (10) according to claim 1, wherein, The reinforcing fiber layer (24) extends over a portion of the connecting portion.

3. The reinforcement according to claim 1, wherein the reinforcing fiber layer (24) is disposed on a plurality of fiber layers (22) at one end of the fiber reinforcement (20) along the thickness direction.

4. The reinforcement (10) according to claim 1, comprising at least one additional reinforcing fiber layer (24') disposed in the stack of fiber layers (22).

5. The reinforcement according to claim 1, comprising a chain stitch seam disposed at the end of the fiber reinforcement (20) along the width direction.

6. The reinforcement (10) according to claim 1, wherein the fiber layer (22) and the reinforcing fiber layer (24) are sewn together by a knitted stitch.

7. The reinforcing member (10) according to claim 1, wherein the tension of the sewing thread (30) in the connecting portion is lower than the tension of the sewing thread (30) in the central portion.

8. The reinforcement (10) according to claim 1, wherein the stitches (32) are more densely distributed in the central portion than the stitches (32) are distributed in the connecting portion.

9. The reinforcement according to claim 1, wherein the stitching (30) sewn on the end portion and the connecting portion has excess length.

10. A nacelle (100) comprising the reinforcement (10) according to claim 1.

11. An aircraft engine (1000) comprising a nacelle (100) according to claim 10.

12. A method for manufacturing a bending reinforcement (10) according to claim 1, comprising: The sewing step (E1) involves forming a fiber reinforcement (20) by sewing together multiple fiber layers (22) and reinforcing fiber layers (24). The lay-up step (E2) involves placing the fiber reinforcement (20) onto the reinforcement mold (40). Impregnation step (E3), wherein the fiber reinforcement (20) placed on the reinforcement mold (40) is impregnated with resin. Polymerization step (E4), in which the resin impregnated in the fiber reinforcement (20) is cured.

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