Blades made of composite materials with three-dimensional braided fiber reinforcement and two-dimensional braided surface layer and their manufacturing method

Abstract

A blade (10) for an aero gas turbine engine includes, in the longitudinal direction (DL) a blade root (11), a shank (12), and a blade body (13), the blade body extending in the longitudinal direction between the shank (12) and the blade tip (14), and in the transverse direction (DT) between a leading edge (40) and a trailing edge (131) made of metallic material. The blade includes a blade core (20) made of a composite material having three-dimensionally woven fiber reinforcement forming part of the blade root, shank, and blade body (21). The blade also includes a surface layer (30) made of a composite material having two-dimensionally woven fiber reinforcement surrounding the blade body portion (21) of the blade core (20), the surface layer being interposed between the leading edge (40) made of metallic material and the leading edge of the blade body portion of the blade core to define a thinned leading edge portion, the surface layer comprising one or more two-dimensionally woven layers, each woven layer wound around the blade body portion of the blade core, and the surface layer also defining a thinned trailing edge.

Description

Technical Field

[0001] This invention relates to the general field of manufacturing blades made of composite materials having fiber reinforcements densified by a matrix obtained by injecting a liquid composition containing a matrix precursor into a fiber preform. Background Technology

[0002] The target area is gas turbine blades for aircraft engines or industrial turbines, and more specifically, but not exclusively, the target area is fan blades for aircraft engines.

[0003] The manufacture of blades made of composite materials includes the following steps:

[0004] a) Producing fiber structures through three-dimensional or multi-layer weaving.

[0005] b) Compacting and shaping the fiber structure.

[0006] c) Place the fiber preform obtained in this manner into an injection molding tool (RTM).

[0007] d) Injecting a liquid precursor composition of a matrix material, such as a resin, into the fiber preform.

[0008] e) Converting the liquid composition into a matrix to obtain a molded element made of a composite material comprising fiber reinforcement densified by the matrix.

[0009] In particular, the production of blades made of composite materials is described in document US2005 / 0084377, which are obtained from fiber reinforcement produced by three-dimensional weaving and densified by a matrix.

[0010] Three-dimensional (3D) or multi-layered weaving imparts excellent mechanical strength to blades made of composite materials. However, in sections of the blade with small thicknesses (approximately a few millimeters), such as the leading and / or trailing edges, it is more difficult to achieve the same level of mechanical strength as 3D or multi-layered weaving. In practice, from a mechanical point of view, and according to certification requirements, the leading and trailing edges must be able to withstand or limit damage when subjected to various stresses, such as impacts with birds or repetitions during flight cycles (erosion / life).

[0011] The difficulty in obtaining thin sections with good mechanical strength through three-dimensional weaving is explained as follows:

[0012] - Large dimensions or fineness of strands or yarns used for 3D or multi-layer braiding, in the millimeter range, and

[0013] - The number of warp or weft yarn layers necessary to ensure good mechanical strength, because it is more difficult to achieve optimal mechanical strength by interlacing only two layers of yarn (the minimum number of warp or weft yarn layers to form a 3D or multi-layered weave) than by interlacing a large number of yarn layers.

[0014] From an aerodynamic performance perspective, reducing the thickness of the upstream (leading edge) and downstream (trailing edge) ends of fan blades can increase aerodynamic efficiency and behavior. In fact, reducing the thickness of the leading and / or trailing edges allows for a bypass that restricts the blade profile. This bypass results in Mach peaks in the transonic and supersonic sections (at the blade tip), which are detrimental to fan performance. Furthermore, primarily for sections with a height greater than 60%, the reduction in thickness decreases profile losses (basal losses) at the trailing edge. This reduction in thickness has a direct impact on the machine's efficiency and, consequently, its energy consumption. Summary of the Invention

[0015] Therefore, the object of the present invention is to provide a solution for blades made of composite materials that does not have the above-mentioned disadvantages and makes it easy to form fine parts with good mechanical properties on the blade.

[0016] To this end, the present invention provides a blade for an aircraft gas turbine engine, the blade comprising, in the longitudinal direction, a blade root, a shank, and an airfoil body extending in the longitudinal direction between the shank and the blade tip, and in the transverse direction between a leading edge and a trailing edge made of a metallic material. The blade includes a blade core made of a composite material having three-dimensionally woven fiber reinforcement forming the blade root, shank, and airfoil body portions. The blade is characterized in that it further includes a surface layer made of a composite material having two-dimensionally woven fiber reinforcement surrounding the airfoil body portion of the blade core. The surface layer is inserted between the leading edge made of a metallic material and the leading edge of the airfoil body portion of the blade core to define a thinned leading edge portion. The surface layer includes one or more two-dimensionally woven layers, each woven layer wound around the airfoil body portion of the blade core. The surface layer further defines a trailing edge.

[0017] Therefore, in the blade according to the invention, the dimensions of the leading and / or trailing edges are determined by a surface layer with two-dimensionally woven fiber reinforcement, which, by definition, has a smaller thickness than three-dimensional weaving. Thus, the blade according to the invention has a thinner leading and / or trailing edge than blades made entirely of composite materials produced from three-dimensionally woven fiber reinforcement, while possessing good mechanical strength, particularly against impact, because the common matrix between the fiber reinforcement of the blade core and the fiber reinforcement of the surface layer made of composite material ensures the distribution of mechanical stress or force between the weaves of these two elements.

[0018] According to the specific features of the blade of the present invention, the ends of each two-dimensional braided layer are joined at the suction side of the airfoil body at positions corresponding to 50% or more of the chord length of the blade, which is measured from the leading edge to the trailing edge of the blade. Therefore, the fiber reinforcement of the surface layer made of composite material has a continuous braid in the region of the leading edge of the blade, which ensures good mechanical strength in the region of the blade exposed to impacts from foreign objects (birds, hail, etc.).

[0019] Another specific feature of the blade according to the invention is that the leading and trailing edges of the blade have a thickness between 0.2 mm and 1.5 mm.

[0020] According to another specific feature of the blade of the invention, the filler material is present at least between the distal end of the leading edge of the airfoil body portion of the blade core and the surface layer made of composite material. This allows for better control over the final shape of the blade's leading edge and avoids a lack of material between the leading edge of the airfoil body portion of the blade core and the surface layer made of composite material.

[0021] According to another specific feature of the blade of the invention, the three-dimensionally woven fiber reinforcement of the blade core comprises carbon fiber yarns, while the fiber reinforcement of the surface layer comprises both carbon fiber yarns and glass fiber yarns. The partial use of glass fiber yarns in the surface layer, made of composite materials, increases deformation at the airfoil body fracture point of the blade, and thus increases its impact resistance.

[0022] Another object of the present invention is a method for manufacturing blades for an aircraft gas turbine engine, comprising at least:

[0023] - Producing fiber blade core blanks through three-dimensional weaving.

[0024] - Cut the fiber blank to obtain a fiber blade core preform, which includes a preform portion at the blade root, a preform portion at the shank, and a preform portion at the airfoil body in the longitudinal direction. The preform portion at the airfoil body extends in the longitudinal direction between the preform portion at the shank and the tip, and in the transverse direction between the leading edge and the trailing edge.

[0025] - Wrap one or more two-dimensional braided layers around the preform portion of the airfoil body.

[0026] - Position the leading edge, made of metallic material, on one or more two-dimensional woven layers at the leading edge of the preformed part of the airfoil body section.

[0027] - Place the fiber preform of the blade core, which is wound with one or more two-dimensional braided layers, and its leading edge into an injection mold.

[0028] - Inject resin into the fiber preform of the blade core and one or more two-dimensional braided layers.

[0029] - The resin is converted into a matrix to obtain a blade comprising a blade core made of a fiber-reinforced composite material with three-dimensional weave, a surface layer made of a fiber-reinforced composite material with two-dimensional weave and an airfoil body portion existing around the blade core, and a leading edge made of a metallic material fixed to the surface layer.

[0030] According to a specific feature of the method of the invention, during the winding of one or more two-dimensional braided layers around a preform portion of the airfoil body portion, the ends of each two-dimensional braided layer are engaged at the surface of the preform portion of the airfoil body portion intended for forming the suction side of the blade, and at a position corresponding to 50% or more of the chord length of the blade measured from the leading edge to the trailing edge.

[0031] Another specific feature of the method according to the invention is that each two-dimensional braided layer has a thickness of about 0.2 mm.

[0032] According to another specific feature of the method of the invention, before wrapping one or more two-dimensional braided layers around the preform portion of the airfoil body portion, the filler material is disposed at least at the distal end of the leading edge of the preform portion of the airfoil body portion. The filler material may also be placed at the distal end of the trailing edge of the spar preform portion.

[0033] Another specific feature of the method according to the invention is that the three-dimensional braided fiber reinforcement of the blade core comprises carbon fiber yarns, and the fiber reinforcement of the surface layer comprises carbon fiber yarns and glass fiber yarns. Attached Figure Description

[0034] Figure 1 This is a perspective view of a blade according to an embodiment of the present invention.

[0035] Figure 2 yes Figure 1 A cross-sectional view of the blade.

[0036] Figure 3 A three-dimensional braided fiber preform, intended for the production of a fiber preform according to an embodiment of the invention, is shown in a very schematic manner.

[0037] Figure 4 From Figure 1 A schematic perspective view of the fiber preform of the blade core obtained from the fiber blank.

[0038] Figure 5 This is a schematic perspective view showing the surroundings Figure 4 The fiber preform of the blade core is wound with a two-dimensional braided layer.

[0039] Figure 6 This is a schematic perspective view, showing the perspective view in... Figure 5 A metal leading edge is placed on the preform. Detailed Implementation

[0040] The blades according to the invention can be specifically configured for blades of shrouded moving wheels, such as fan blades, or for blades of shrouded moving wheels (such as in so-called "open rotor" aircraft engines).

[0041] Figure 1 A fan blade 10 for an aircraft gas turbine engine is shown, the blade having a longitudinal direction D L The upper part includes a blade root 11, a shank 12, and an airfoil body 13, the airfoil body being in the longitudinal direction D L It extends between the stalk 12 and the blade tip 14, and in the transverse direction D T It extends between the leading edge 40 and the trailing edge 131, which are made of metallic material.

[0042] like Figure 1 and Figure 2 As shown, the blade 10 includes a blade core made of composite material 20, which has three-dimensionally woven fiber reinforcement forming the blade root 11, the shank 12, and the airfoil body portion 21, which forms at least a portion of the airfoil body 13. The airfoil body portion is located in the longitudinal direction D... L It extends between the stalk 12 and the blade tip 14, and in the transverse direction D T It extends between the front edge 210 and the rear edge 211.

[0043] According to the invention, the blade 10 further includes a surface layer made of composite material 30 surrounding the airfoil body portion 21 of the blade core 20, the composite material having two-dimensional woven fiber reinforcement. The surface layer 30 is interposed between a leading edge made of metallic material 40 and the leading edge 210 of the airfoil body portion 21 of the blade core to define a thinned leading edge portion. In the embodiments described herein, a first filler material 50, which may be foam or resin, is present, in particular, between the distal end 210a of the leading edge 210 of the airfoil body portion 21 of the blade core and the surface layer made of composite material 30. The surface layer 30 is also present around the trailing edge 211 of the airfoil body portion 21 of the blade core to define a thinned trailing edge 131. In the embodiments described herein, a second filler material 51, which may be foam or resin, is present, in particular, between the distal end 211a of the trailing edge 211 of the airfoil body portion 21 of the blade core and the surface layer made of composite material 30. However, blades according to the invention without filler material at the leading and trailing edges of the airfoil body portion can be produced.

[0044] As described below, the surface layer made of composite material 30 includes one or more two-dimensional braided layers, each layer being wound around the spars of the blade core.

[0045] Figure 3 The weaving of the fiber preform 100 is shown schematically, from which the fiber preform 200 from which the blade core can be extracted is a fiber preform. Figure 4 ).

[0046] A fiber preform 100 is obtained by three-dimensional weaving, or 3D weaving, or by multi-layer weaving in a known manner using a jacquard loom, on which bundles of warp yarns or strands 101 have been arranged in multiple layers, the warp yarns being connected by weft yarn layers 102 also arranged in multiple layers, some of which include a woven fabric, as described in detail below. In the illustrated embodiment, the 3D weaving is an “interlocking” weaving. Here, the term “interlocking” weaving refers to a weaving in which each layer of weft yarns connects multiple layers of warp yarns, wherein all yarns in the same weft yarn column have the same movement in the weaving plane. In particular, detailed exemplary embodiments for forming fiber-reinforced fiber preforms for aircraft engine blades from 3D-woven fiber preforms are described in detail in documents US7 101 154, US 7 241 112, and WO 2010 / 061140.

[0047] The fiber preform 100 is woven into a strip, which is typically in the longitudinal direction D corresponding to the longitudinal direction of the blade to be produced. L Extending upwards. In the fiber preform 100, the fiber preform 200 of the blade core has a variable thickness determined according to the longitudinal thickness and profile of the blade to be produced. In the portion intended to form the root preform, the fiber preform 200 has a portion corresponding to the additional thickness of the root preform portion 203. The fiber preform 200 extends with a reduced thickness corresponding to the shank preform portion 204 intended to form the blade shank, and then extends a preform portion 205 of the airfoil body portion intended to form the airfoil body portion of the blade core, which extends between the shank preform portion 204 and the tip 206. The preform portion 205 of the airfoil body portion extends in the direction perpendicular to the longitudinal direction D. L Horizontal direction D T The airfoil has a profile with a variable thickness between its leading edge 2050 and its trailing edge 2051. The preformed portion 205 of the airfoil body includes a first surface 2052 and a second surface 2053 extending between edges 2050 and 2051. Figure 4 ), and is designed to form the pressure side and suction side of the blade with the composite surface, or vice versa.

[0048] The fiber preform 200 of the blade core is woven into a single piece and must have a near-final shape and size (“clean shape”) of the blade core after the non-woven yarn of the blank 100 is cut. For this purpose, in components with fiber structures having varying thicknesses, such as in components with reduced thickness having a shank preform portion 204, the thickness reduction of the preform is achieved by gradually removing the weft yarn layer during weaving.

[0049] Once the fiber preform 200 of the blade core in blank 100 has been woven, the non-woven yarn is cut. Then, the desired result is obtained. Figure 4 The fiber preform 200 of the blade core shown is a single-piece woven structure. The leading edge 2050 of the preform portion 205 of the airfoil body portion is intended to form the leading edge 210 of the airfoil body portion 21 of the blade core 20, while the trailing edge 2051 of the preform portion 205 of the airfoil body portion is intended to form the trailing edge 211 of the airfoil body portion 21 of the blade core 20.

[0050] The final blade has a small thickness, for example, less than 1 mm, at its leading and / or trailing edges. This small thickness is difficult to achieve with three-dimensional weaving due to the large size or fineness of the warp and weft yarns, and the minimum number of yarn layers required to ensure good mechanical strength. In the embodiment described herein, the distal portion 210a of the leading edge 210 of the airfoil body portion 21 and the distal portion 211a of the trailing edge 211 of the sparsity 21 each have a thickness of approximately 1.5 mm. 210a and E 211a ( Figure 2 ).

[0051] According to the present invention, the leading and trailing edges of the airfoil body portion can be thinned by a composite surface layer reinforced with two-dimensionally woven fibers. More precisely, as Figure 5 As shown, a two-dimensional braided layer (in this case, two layers 230 and 231) is wound around the preform portion 205 of the airfoil body section. In the embodiment described herein, before winding the first layer 230, a first filler material 50 and a second filler material 51 are respectively placed on the distal ends 2050a and 2051a of the leading edge 2050 and the trailing edge 2051 of the spar portion of the airfoil body section 205. Figure 4 ).

[0052] The two-dimensional braided layers 230 and 231 each have a thickness of 0.2 mm, which enables the formation of a surface preform 230 having a thickness E corresponding to the surface layer made of composite material 30. 30 The thickness is 0.4 mm. In the embodiments described herein, the ceramic surface preform allows for the acquisition of leading-edge and trailing-edge preform portions, each having a thickness of 0.8 mm, positioned on the final blade.BA and E BF ( Figure 2 The leading and trailing edges of the blade preferably have a thickness between 0.2 mm and 1.5 mm.

[0053] In particular, two-dimensional layer winding can be produced automatically by robots, which enables good repeatability and coverage control (without winding, extrusion, etc.).

[0054] This results in a preform assembly 250, which includes a fiber preform 200 for the blade core, filler materials 50 and 51, and a surface preform 230. The next step involves positioning a leading edge made of metal material 40 onto the preform assembly 250 at the leading edge of the spar preform portion. Figure 6 ).

[0055] The preform assembly 250 and the leading edge made of metal material 40 are placed in an injection mold. Then, the liquid matrix precursor is injected into the holes of the fiber preform of the blade core and into the two-dimensional braided layer that forms the surface preform.

[0056] More precisely, the component is placed in a mold that can be sealed with a recess having the shape of the final molded part, and in particular, being capable of having a twisted shape corresponding to the final shape of the airfoil. The mold is then closed, and a liquid matrix precursor (e.g., resin) is injected into the entire recess to impregnate the entire fibrous portion of the component.

[0057] After removing any solvents and polymer crosslinking, the precursor is converted into a matrix through heat treatment, typically by heating a mold, i.e., its polymerization. The preform is always held in the mold, the shape of which corresponds to the shape of the blade. In particular, the matrix can be obtained from epoxy resins, such as the high-performance epoxy resins sold by CYTEC under reference PR520.

[0058] According to aspects of the invention, densification of fiber preforms can be achieved by a known method of resin transfer molding (RTM). According to the RTM method, the fiber preform is placed in a mold with an airfoil-shaped outer surface. A thermosetting resin is injected into an internal space defined between a part made of a rigid material and the mold, and this internal space includes the fiber preform. Typically, a pressure gradient is established in this internal space between the resin injection site and the orifice for resin removal to control and optimize the impregnation of the preform with the resin.

[0059] For example, the resin used can be an epoxy resin. Resins suitable for the RTM method are well known. They preferably have low viscosity to facilitate their injection into the fibers. The choice of resin temperature class and / or chemical properties is determined based on the thermomechanical stress the component must withstand. Once the resin is injected into the entire reinforcement, its polymerization is carried out by heat treatment according to the RTM method.

[0060] The resin acts as an adhesive between the fiber reinforcement of the blade core 20 and the fiber reinforcement of the surface layer made of composite material 30, thus ensuring the distribution of mechanical stress or force between the fabrics of the two elements.

[0061] After the resin is converted into a matrix, the part is demolded. Then, the desired result is obtained. Figure 1 The blade 10, wherein the blade core made of composite material 20 forms part of the blade root 11, the shank 12 and the airfoil body 13, and the surface layer made of composite material 30 forms another part of the airfoil body 13, the trailing edge 131 of the blade and the metal leading edge 40.

[0062] According to a specific feature of the invention, one or more two-dimensional braided layers are wound around a preformed portion of the airfoil body section, such that the ends of each two-dimensional braided layer are joined at the surface of the airfoil body section intended to form the suction side of the blade, and at a location corresponding to 50% or more of the chord length of the blade measured from the leading edge to the trailing edge. Thus, the fiber reinforcement of the surface layer 30, made of composite material, has a continuous weave in the region of the leading edge of the blade, which ensures that when exposed to the transverse direction D... T Good mechanical strength in the blade region impacted by external objects (birds, hail, etc.). At the ends of one or more layers, at positions corresponding to 50% or more of the blade chord length measured from the leading edge 40 to the trailing edge 131 of the blade 10, a joint 31 is formed on the suction side of the airfoil body. Figure 1 and Figure 2 Slight overlap is permissible between the ends of each layer. Bonding between the layers is ensured by injected resin, which transforms into a matrix within the layers. Optionally, the ends of these layers can be secured together by stitching before resin injection.

[0063] According to another specific feature of the invention, the three-dimensionally woven fiber reinforcement of the blade core comprises carbon fiber yarns, while the fiber reinforcement of the surface layer comprises both carbon fiber yarns and glass fiber yarns. The partial use of glass fiber yarns in the surface layer, made of composite materials, increases deformation at the fracture point of the blade's airfoil body and thus increases its impact resistance.

Claims

1. A blade (10) for an aircraft gas turbine engine, said blade being in the longitudinal direction (D L The blade includes a blade root (11), a shank (12), and an airfoil body (13), the airfoil body being longitudinally located between the shank (12) and the blade tip (14), and transversely located between the leading edge and trailing edge (131) made of metallic material. T The blade extends to include a blade core made of a composite material having three-dimensionally woven fiber reinforcement forming the blade root, shank, and airfoil body portion (21), characterized in that... The blade also includes a surface layer made of a composite material having a two-dimensionally woven fiber reinforcement around an airfoil body portion (21) of the blade core. The surface layer is inserted between a leading edge made of a metallic material and the leading edge (210) of the airfoil body portion of the blade core to define a thinned leading edge portion. The surface layer includes one or more two-dimensionally woven layers (230, 231), each woven layer wrapped around a sparsity of the blade core. The surface layer further defines the trailing edge of the blade. At least at the distal end (210a) of the leading edge (210) of the airfoil body portion (21) of the blade core, there is a filler material (50) between the surface layer made of the composite material and the surface layer. The ends of each two-dimensionally woven layer (230, 231) are joined at the suction side of the airfoil body (13) at a position corresponding to 50% or more of the chord length of the blade measured from the leading edge to the trailing edge (131) of the blade (10).

2. The blade according to claim 1, wherein, The leading and trailing edges (131) of the blade have a thickness between 0.2 mm and 1.5 mm.

3. The blade according to claim 1, wherein, The three-dimensional woven fiber reinforcement of the blade core includes carbon fiber yarns, and the surface fiber reinforcement includes carbon fiber yarns and glass fiber yarns.

4. A method for manufacturing blades for an aircraft gas turbine engine, comprising at least: - Producing fiber blade core blanks (100) through three-dimensional weaving. - Cut the fiber preform to obtain a fiber blade core preform (200), the fiber blade core preform being in the longitudinal direction (D L The airfoil includes a blade root preform portion (203), a shank preform portion (204), and an airfoil body preform portion (205), the airfoil body preform portion extending longitudinally between the shank preform portion (204) and the tip (206), and extending laterally between the leading edge and the trailing edge (D). T Extending upwards, - Wrap one or more two-dimensional braided layers (230, 231) around the preformed part (205) of the airfoil body portion. - Position the leading edge, made of metallic material, on one or more two-dimensional woven layers at the leading edge of the preformed part (205) of the airfoil body section. - The fiber preform (200) of the blade core, which is wound with one or more two-dimensional braided layers (230, 231), and the leading edge are placed into the injection mold. - Inject resin into the fiber preform of the blade core and one or more two-dimensional braided layers. - The resin is converted into a matrix to obtain a blade (10), the blade comprising a blade core made of a composite material having three-dimensionally woven fiber reinforcement; The surface layer is made of composite material and has two-dimensional woven fiber reinforcement present around the airfoil body portion (21) of the blade core; and a leading edge made of a metallic material, said leading edge being fixed to the surface layer, The feature is that, before wrapping one or more two-dimensional braided layers (230, 231) around the preform portion (205) of the airfoil body portion, a filler material (50) is placed at least at the distal end (2050a) of the leading edge of the preform portion of the airfoil body portion. During the winding of one or more two-dimensional braided layers (230, 231) around the preform portion (205) of the airfoil body portion, the ends of each two-dimensional braided layer are joined at the surface of the preform portion (205) intended to form the suction side of the blade, and at a position corresponding to 50% or more of the chord length of the blade measured from the leading edge to the trailing edge.

5. The method according to claim 4, wherein, Each two-dimensional braided layer (230, 231) has a thickness of approximately 0.2 mm.

6. The method according to claim 4 or 5, wherein, The three-dimensional woven fiber reinforcement of the blade core includes carbon fiber yarns, and the surface fiber reinforcement includes carbon fiber yarns and glass fiber yarns.

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