CHARACTERIZATION TEST SPECIMEN FOR A TURBOMACHINE PART AND CORRESPONDING MANUFACTURING PROCESS

Abstract

The invention relates to a test specimen (1) for characterizing a part for an aircraft turbomachine, the specimen (1) being made of a composite material based on a woven fibrous reinforcement (3) embedded in an organic or polymeric matrix (6), the specimen (1) further comprising at least one non-metallic identification support (2) for the specimen, which is arranged within the composite material, the identification support (2) being of the radio-frequency identification type, being positioned away from the fibrous reinforcement (3) and located within an excess thickness (SE) of matrix surrounding the fibrous reinforcement (3). Figure for the abstract: Figure 1

Description

Title of the invention: CHARACTERIZATION TEST FOR A TURBOMACHINE PART AND CORRESPONDING MANUFACTURING METHOD Technical field of the invention

[0001] The present invention relates to the field of characterization tests for composite material parts, and in particular to characterization specimens for turbomachine parts so as to study their behavior and properties under certain stresses. The invention also relates to the method for manufacturing such a characterization specimen. Technical background

[0002] For several years, turbomachines have been equipped with various composite material parts in order to improve their thermomechanical resistance capabilities and reduce their masses. Organic matrix composite materials (OMCs), which include a fiber reinforcement made by weaving and embedded in an organic matrix, allow, for example, the manufacture of fan blades or fan casings. Turbomachine parts made of composite material operate in restrictive environments which can accelerate their wear. Tests or trials are regularly carried out on samples or specimens of these turbomachine parts in order to verify their service life and mechanical and / or thermal properties under certain stresses. The specimens use various fiber reinforcements with different sizes, different patterns and different materials.

[0003] Generally speaking, the test pieces are in the form of plates or panels which are cut into several pieces and which can be stored for many years in “library” cabinets. Indeed, these test pieces which have already been tested can be subject to subsequent additional tests following an event occurring for example on a certified configuration. Turbomachine parts can rarely or not at all be used or be sampled to carry out these tests, hence the storage of these test pieces and their subsequent uses.

[0004] These test tubes are not correctly listed in cabinets and databases, which means that operators have to carry out time-consuming searches. In most cases, the search is done visually.

[0005] The invention aims to avoid the aforementioned drawbacks. Summary of the invention

[0006] The objective of the invention is to provide an optimal solution for finding quickly and easily characterization specimens while being economical.

[0007] The invention relates to a test piece for characterizing a part for an aircraft turbomachine, the test piece being made of a composite material based on a woven fiber reinforcement and embedded in an organic or polymeric matrix, the test piece further comprising at least one support for identifying the test piece which is non-metallic and which is arranged in the composite material, the identification support being of the radio-identification type, being placed at a distance from the fiber reinforcement and located in an excess thickness of matrix surrounding the fiber reinforcement.

[0008] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, thanks to the identification support, such a configuration makes it possible, on the one hand, to quickly and easily locate the characterization specimen in a library containing several of these specimens whose dimensions and shapes are similar or even almost identical, and on the other hand to achieve traceability of the characterization specimen. RFID radio identification type identification supports are widely available on the market, which leads to a high availability and supply of these and a lower cost. The performance of the identification chain depends heavily on the environment in which the support is placed and how this support is designed. This non-metallic identification support being of a very small thickness and being placed in the excess thickness of the matrix, this makes it possible to increase the distance between the fiber reinforcement and the latter.Similarly, the fact that the identification support is placed in the matrix makes it possible to preserve its physical integrity by protecting it from the external environment and from its detachment, for example, from the surface of the test piece.

[0009] The test piece according to the invention may comprise one or more of the following characteristics, considered independently of one another or in combination with one another:

[0010] - the matrix excess thickness measured between an external layer of the fibrous reinforcement and an external surface of the test piece is between 1 and 10 mm.

[0011] - the identification support has a thickness of between 0.01 mm and 0.5, and preferably 0.2 mm.

[0012] - the identification medium is configured to operate at a frequency of between 860 MHz and 930 MHz.

[0013] - the test piece comprises several identification supports which are arranged at opposite ends or edges of the test piece.

[0014] - the test piece has a non-conductive positioning element which is arranged against the outer layer of the fibrous reinforcement and which carries at least one identification support.

[0015] - the test piece has a parallelepiped shape and in that supports identification are arranged at each end or corner of the test piece.

[0016] - the identification media are identical and include references identical identification.

[0017] - the identification supports each have an identification reference, each identification reference comprising an identical main number and a different, unique secondary number.

[0018] - the fibers of the fibrous reinforcement are made of carbon.

[0019] - the organic or polymeric matrix is ​​a thermosetting or thermo resin plastic.

[0020] The present invention also relates to a method for manufacturing a characterization test piece as mentioned above, the method comprising the steps of:

[0021] - supply of fiber reinforcement,

[0022] - provision of at least one identification medium,

[0023] - placing the fiber reinforcement and the identification support in a mold, the identification support being placed at a distance from the fibrous reinforcement,

[0024] - injection of a matrix into the mold so as to simultaneously embed the reinforcement fibrous and the identification support, and

[0025] - densification so as to densify the matrix and the identification support in the excess thickness of the matrix.

[0026] The method may comprise one or more of the following features or steps, considered independently of one another or in combination with one another:

[0027] - the method comprises a step of inserting a non-positioning element conductor between the fiber reinforcement and the mold, the positioning element carrying the identification support and being arranged against the fiber reinforcement.

[0028] - the positioning element comprises a foam, a clip, a spring, a washer or block.

[0029] - the identification support moves away from the fibrous reinforcement during filling of the mold with resin. Brief description of the figures

[0030] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0031] - [Fig.l] is a schematic and perspective representation of an example of a test piece for characterizing a part for a turbomachine, the test piece comprising identification means according to the invention;

[0032] - [Fig.2] is a schematic and perspective representation of an example of fiber reinforcement for a characterization test piece made of composite material according to the invention;

[0033] - [Fig.3] is a schematic and sectional representation of an example characterization test piece according to the invention;

[0034] - [Fig.4] shows in the form of a flowchart the different stages of a process of manufacturing a characterization test piece according to the invention;

[0035] - [Fig.5] represents a step of arranging an identification support in a injection mold according to one embodiment of the invention;

[0036] - [Fig.6] is a schematic representation of a reading step of a means identification of a characterization test piece stored with several characterization test pieces according to the invention;

[0037] - [Fig.7] is an example of an embodiment of a positioning element intended for carry at least one identification medium according to the invention;

[0038] - [Fig.8] is another example of the embodiment of a positioning element intended to carry at least one identification support according to the invention;

[0039] - [Fig.9] is another example of the embodiment of a positioning element intended to carry at least one identification support according to the invention; and

[0040] - [Fig. 10] is yet another example of the embodiment of a posi element operation intended to carry at least one identification support according to the invention. Detailed description of the invention

[0041] With reference to [Fig.l], a characterization test piece 1 of a turbomachine part, in particular an aircraft part, is shown schematically. The turbomachine (not shown) makes it possible to move the aircraft from an incoming air flow.

[0042] Generally, the turbomachine comprises, from upstream to downstream, a compressor assembly (with a low-pressure compressor and a high-pressure compressor), a combustion chamber and a turbine assembly (with a low-pressure turbine and a high-pressure turbine). The turbine assembly makes it possible to drive the compressor assembly in rotation. In the present invention, and generally, the terms "upstream" and "downstream" are defined in relation to the circulation of gases in the turbomachine and here along the longitudinal axis of the turbomachine.

[0043] The turbomachine may comprise upstream a fan which makes it possible to accelerate the air flow downstream and at least in part towards the compressor assembly. The fan comprises a disk, integral in rotation with a shaft of the low pressure compressor. Fan blades extend from the periphery of the disk and through the air flow.

[0044] The turbomachine comprises one or more parts made of composite material intended to improve its performance. An example of a composite material part is a fan blade, a stator blade (installed downstream of the fan), a compressor blade, a turbine blade, a casing, or any other part. Before these parts can be manufactured and authorized for commissioning or certification, they undergo thermomechanical resistance tests using characterization specimens in test benches.

[0045] The characterization test piece 1 is made of a composite material. The test piece also comprises at least one identification support 2 thereof.

[0046] With reference to [Fig. 2], the composite material comprises a fibrous reinforcement 3 embedded in the matrix. The fibrous reinforcement comprises weft threads 4 and warp threads 5 which are woven together. The threads 4, 5 are woven according to a three-dimensional weave (or 3D weave) or a multi-layer weave or even a two-dimensional weave (2D weave).

[0047] In the present invention, we understand by the expression "three-dimensional weaving" or "3D weaving" a weaving mode in which warp threads 5 are linked to weft threads 4 on several layers. The fibrous reinforcement 3 could also be produced according to a three-dimensional interlock weaving or "3D interlock weaving". We understand by the expression "3D interlock weaving" a weaving mode in which several layers (formed of warp and weft threads) are linked together. We understand by the expression "multi-layer weaving" a weaving mode in which several layers produced according to a 2D weaving are assembled.

[0048] The nature of the weft threads 4 and the warp threads 5 as well as the selected reinforcement will make it possible to define the mechanical properties of the preform (or fibrous texture or fabric) forming the fibrous reinforcement 3 and also of the characterization test piece 1.

[0049] The threads 4, 5 constituting the fibrous reinforcement comprise metallic, carbon, glass, Kevlar, thermoplastic (such as polyamide), ceramic, alumina, silica, silicon carbide or a mixture of these fibers. The carbon and metallic fibers are electrically conductive fibers. The thermoplastic and aramid fibers are non-electroconductive fibers. Preferably, but not limited to, the fibers of the fibrous reinforcement 3 are made of carbon in the present example.

[0050] In [Fig. 3], the matrix 6 allowing densification of the fiber reinforcement can be an organic matrix or a polymer matrix. The polymer matrix 6 can be a thermosetting resin based on epoxy or bismaleimide. The polymer matrix can also be a thermoplastic resin or of a different nature. The matrix is ​​not electrically conductive. In the present description, the terms “resin” and “matrix” are equivalent.

[0051] The identification medium 2 is configured to provide data relating to to the test piece 1. This data relates specifically to the location of the characterization test piece 1 in a library. The identification medium 2 is of the RFID type. This is in the form of a label using RFID technology. The identification medium 2 comprises data storage means and a radio antenna configured to, on the one hand, receive a reading order and, on the other hand, transmit the information relating to the data. The antenna is connected to an RFID integrated circuit comprising the storage means. The antenna and the circuit are advantageously printed on a support sheet of the identification medium.

[0052] Advantageously, the identification support 2 is non-metallic. In other words, the identification support 2 is non-conductive. The non-metallic identification supports 2 have a small thickness, typically between 0.1 mm and 0.5 mm. Preferably, the thickness of the support is 0.2 mm. This type of support 2 is used for ultra high frequency (UHF) applications. A metallic identification support 2 has a greater thickness, such as 1.5 mm and is intended for high frequency or UHF applications.

[0053] By the term ultra high frequency, we mean a band of radio spectrum between 860 MHz and 930 MHz. The identification medium 2 is configured to operate between these two frequency limits (between 860 and 930 MHz). Of course, it is possible to use an identification medium 2 configured to operate in all the frequencies of the radio spectrum, in particular on the electromagnetic frequency bands standardized for RFID type media. In these cases, the HF (High Frequency) and UHF radio spectrum bands are preferred. The following examples are applicable: between 120 and 150 kHz (Low Frequency (LF)), around 13.56 MHz (HF), around 433 MHz, between 902 and 928 MHz (UHF), between 245 and 5800 MHz (Supra High Frequency (SHF) and between 3.1 and 10 GHz (Ultra Wide Band (UWB)).

[0054] The identification medium 2 is advantageously passive and does not include any power supply means which would be likely to increase its mass. In this case, the identification medium 2 is powered by electromagnetic waves emitted by an RFID type reader.

[0055] The identification support 2 is arranged in the composite material and in particular at a distance from the fiber reinforcement. In other words, the identification support 2 is not in contact with the fiber reinforcement 3. If the fiber reinforcement 3 comprises metal fibers, this makes it possible not to disturb the radial signals and the proper functioning of the identification support 2. The fact that the identification support 2 is in the pure matrix makes it possible to protect it from the external environment and from metal components which would be placed near the library where the test pieces 1 will be stored.

[0056] As we can see in [Fig. 3], the identification support 2 is located in an excess thickness SE of matrix surrounding the fiber reinforcement 3. The excess thickness SE of material is obtained using an injection mold 40 (referenced in [Fig. 5]), intended to accommodate the fiber reinforcement 3, which has dimensions greater than those of the preform. The dimensions are greater by around 25%. The matrix 6 which is injected into the mold fills the space between the internal surface of the mold and an external layer 7 of the fiber reinforcement.

[0057] With reference to [Fig. 3], the excess thickness SE of matrix measured between the external layer 7 (peripheral) of the fiber reinforcement 3 and an external surface 8 of the characterization test piece 1 is between 1 and 10 mm. The identification support 2 is embedded in this excess thickness SE. It is possible that this excess thickness distance is provided only in the areas where the identification support 2 will be installed.

[0058] The characterization test piece 1 shown in [Fig.l] has a parallelepiped shape. The test piece 1 has two opposite faces 9 and four flanks 10 connecting the opposite faces 9. Several identification supports 2 are arranged at the ends 11 or edges of the characterization test piece. In the present example, two identification supports 2 are arranged at each end 11 or corner of the test piece 1 and on each flank 10 of the test piece. There are therefore eight identification supports 2 on this test piece. In this way, if the test piece 1 is cut into several pieces, either in two or even in four, there would always be a corner with identification supports. Of course, the characterization test piece 1 can have any type of shape allowing it to be stored in a library, the arrangement of the identification support(s) and the presence of at least one identification support after cutting.

[0059] The identification supports 2 of each test piece 1 are identical. These supports 2 then have an identical identification reference (or number). In this way, in the event of cutting, each piece or part of test piece 1 will include at least one identification support 2 (it will not be necessary to add more) which allows better traceability of test piece 1 or part of test piece 1.

[0060] According to an alternative, the identification media 2 have a difference between them, in particular in the way of identifying them. In particular, each identification reference comprises an identical main number and a different secondary number. The secondary number is unique. In other words, the identification media 2 can be differentiated by their unique secondary number. For example, with an identification reference with numbers or digits, the last digit being different for each medium.

[0061] We will now describe the method 100 for manufacturing such a test piece 1 according to the flowchart illustrated in [Fig.4]. The manufacturing method 100 comprises a step 110 of providing a fibrous reinforcement 3. The fibrous reinforcement 3 is obtained by weaving fibers (weft threads 4 and warp threads 5 are woven together) and here carbon fibers.

[0062] The method also comprises a step 120 of providing at least one identification medium 2. The identification medium 2 is manufactured beforehand.

[0063] The method comprises a step 130 of placing the fiber reinforcement 3 in the injection mold 40. It is noted, as stated previously, that the mold has dimensions greater than those of the fiber reinforcement 3. This makes it possible to create the excess thickness SE intended to contain the identification support(s) 2 only in the matrix. Generally speaking, in the prior art and unlike the present example, the dimensions of the mold 40 are adjusted to those of the fiber reinforcement 3 to avoid excess matrix thickness since this would have to be removed during surface preparation.

[0064] The method also comprises placing 140 one or more identification supports in the mold 40.

[0065] The support(s) are arranged at a distance from the fibrous reinforcement 3. The identification support(s) are arranged in the space 41 formed between the external layer 7 of the fibrous reinforcement 3 and the internal surface 42 of the mold 40. In other words, the identification support 2 is not integral with the fibrous reinforcement 3.

[0066] According to an exemplary embodiment as illustrated in [Fig. 5], an identification support 2 is carried by a positioning element 43 which is placed against the fibrous reinforcement. The positioning element 43 is non-conductive (or insulating). Advantageously, the positioning element 43 is made of a polymer material.

[0067] The positioning element 43 may in particular be a foam 44, a plastic block, a plastic clip 45, a spring 46 or even a washer 47.

[0068] The foam 44 as shown in [Fig.6] may be that known under the brand name Rohacell® HERO 200. Such foam makes it possible to guarantee the correct positioning of the identification support(s) 2.

[0069] The foam 44 could have a thickness substantially (+ / - 0.5 mm) equal to the space 41 provided between the mold 40 and the fiber reinforcement 3. The thickness of the foam is between 1 and 5 mm. The compression generated by the closing of the cover of the mold 40 makes it possible to keep each identification support in position.

[0070] The material of the foam 44 is intended to support the injection of the matrix and the densification. In particular, the foam 44 can withstand the high temperatures during the injection and polymerization / densification cycle.

[0071] An example of clip 45 or fastener is shown in [Fig.7]. The plastic clip is advantageously used when the space 41 is greater than 2 mm. Manipulation of the clip 45 will be easier in such a space. In the example shown, the clip 45 comprises a first blade 45a and a second blade 45b which are connected by a bottom wall 45c. The bottom wall 45c makes it possible to elastically connect the first and second blades 45a, 45b which are arranged like springs. The bottom wall 45c has a C-shape for this purpose. At least one of the first and second blades 45a, 45b approaches the other and towards their free ends 45aa, 45bb. The first and second blades 45a, 45b are opposite each other. The first blade 45a comprises at its free end 45aa a first engagement handle 45d whose direction is transverse to the direction of the first blade. The second blade 45b comprises at its free end 45bb a second engagement handle 45e whose direction is transverse to the direction of the second blade 45b. The directions of the engagement handles are different and are oriented outward (the engagement handles flare outward).The connecting portion between each blade 45a, 45b and each engagement handle 45a, 45e is curved (with an inwardly concave surface) and allows the clip to be retained on the fiber reinforcement 3 or in contact with the outer layer 7 of the fiber reinforcement 3. A portion of the outer layer of the fiber reinforcement is wedged between the two connecting portions which are tightened onto the fiber reinforcement portion 3. The identification support is arranged on the bottom wall 45c. Other ways of arranging the clip 45 on the fiber reinforcement are possible as well as the way in which the identification support is mounted on the clip 45.

[0072] An example of spring 46 is illustrated in [Fig.8]. The spring is advantageously a compression spring. The spring has an external diameter of between 3 and 10 mm. The length of the spring is between 5 and 50 mm along its main axis. The diameter of the spring wire is of the order of 0.5 mm. The spring 46 is arranged along its length between the external layer 7 of the fiber reinforcement 3 and the mold 40. The identification support is arranged on one end of the spring and opposite the surface of the mold 40.

[0073] Examples of washer 47a, 47b are also illustrated in Figures 9 and 10. The washer may be an elastic washer. For this purpose, the washer 47a is split as in [Fig.9] or has a curvature as in [Fig. 10]. Each washer has a thickness of the order of 2 mm.

[0074] The method comprises a step 150 of injecting a matrix into the mold 40 after its closure. The matrix is ​​advantageously an organic resin. This injection takes place according to RTM technology, this acronym meaning in English Resin Transfer Molding for resin transfer molding, in order to achieve densification of the fiber reinforcement and obtain the test piece 1. The impregnation of the preform by the resin is optimized by applying pressure in the injection chamber. Other methods such as infusion, resin transfer molding known as the English acronym “RTM light” or injection molding of a resin between the preform and a flexible membrane known as “Polyflex” are of course possible.

[0075] During matrix injection, the identification support(s) 2 remain in position at a distance from the fiber reinforcement thanks to the positioning element 43. The matrix fills the space 41 which will trap the identification support(s) 2. This or these latter is / are located between the external layer 7 of the fiber reinforcement 3 and the internal surface of the mold (not shown).

[0076] In the case where the support(s) 2 are arranged in the mold 40 without support (by the positioning element) and without fixing relative to the fiber reinforcement and where a matrix with a high viscosity is used, such as greater than 300 cp, the identification support(s) 2 may move away or deviate from the fiber reinforcement 3.

[0077] The method comprises a densification step 160 in which the matrix is ​​solidified and in which we obtain a rigid test piece 1. In particular, with the densification the fibers are linked together, the stresses are better distributed in the test piece, and the identification support(s) 2 is / are solidified with the matrix. In addition, the solidified matrix makes it possible to protect the fiber reinforcement 3 and the identification support(s) 2 from the external environment.

[0078] The densification comprises polymerization of the matrix in an autoclave or in a press. The matrix 6 provides an electrically insulating character to prevent disturbances with the metal fibers of the fibrous reinforcement 3 which are good conductors or metal components in the external environment of the characterization test piece 1.

[0079] In the case of the identification supports 2 positioned using one or more positioning elements 43, these are considered as a foreign body inside the test piece, but located in an area not used for mechanical and / or thermal characterization.

[0080] [Fig. 5] illustrates a method for acquiring data from the test piece 1 by the identification support(s). An acquisition means 50 is provided to recover the data from the identification support(s) 2. In this figure, we see an operator carrying such an acquisition means 50 near a library 51 containing several test pieces 1 arranged next to each other. When the identification support 2 is in the form of a radio tag, the acquisition means 50 is an RFID reader configured to emit radio frequencies intended to activate the radio tag of the identification support 2. The acquisition means 50 are arranged at a distance of between 0 and 10 m from the identification support. The positioning of the identification support 2 in the matrix increases the detection distance by a few centimeters (10 to 20 cm) up to a few meters (2 to 10m).

[0081] The acquisition means 50 remotely sends a read request to the identification medium 2 in order to activate it. Then, the acquisition medium 2 remotely transfers the data from the storage means to the acquisition means 50. The data which are transmitted here include the identification reference (“serial number” in English) of the characterization test piece 1 and / or the identifier of its configuration (“part number” in English). The acquisition means 5 is associated with a display such as a screen making it possible to display the transferred data. The screen may be rectangular or otherwise shaped while still making it possible to display the data. The screen may display information concerning the test piece, the characteristics of the material of the test piece, the location of the test piece 1 and / or whether there are different parts of this test piece.

Claims

Claims

1. Test piece (1) for characterizing a part for an aircraft turbomachine, the test piece (1) being made of composite material based on a woven fiber reinforcement (3) embedded in an organic or polymeric matrix (6), the test piece (1) further comprising at least one identification support (2) of the test piece which is non-metallic and which is arranged in the composite material, the identification support (2) being of the radio-identification type, being placed at a distance from the fiber reinforcement (3) and located in an excess thickness (SE) of matrix surrounding the fiber reinforcement (3).

2. Test piece (1) according to the preceding claim, characterized in that the excess thickness (SE) of matrix measured between an external layer (7) of the fibrous reinforcement (3) and an external surface (8) of the test piece is between 1 and 10 mm.

3. Test tube (1) according to one of the preceding claims, characterized in that the identification support (2) has a thickness of between 0.01 mm and 0.5 mm, and preferably 0.2 mm.

4. Test tube (1) according to one of the preceding claims, characterized in that the identification medium (2) is configured to operate at a frequency between 860 and 930 MHz.

5. Test tube (1) according to one of the preceding claims, characterized in that it comprises several identification supports (2) which are arranged at opposite ends (11) or edges of the test tube (1).

6. Test piece (1) according to one of claims 2 to 5, characterized in that it has a non-conductive positioning element (43) which is arranged against the outer layer (7) of the fibrous reinforcement and which carries at least one identification support (2).

7. Test tube (1) according to one of the preceding claims, characterized in that the identification supports (2) are identical and include identical identification references.

8. Test tube (1) according to one of claims 1 to 6, characterized in that the identification supports (2) each have an identification reference, each identification reference comprising an identical main number and a different, unique secondary number.

9. Test piece (1) according to one of the preceding claims, characterized in that the fibers of the fibrous reinforcement (3) are made of carbon.

10. Method of manufacturing a characterization test piece according to one of of claims 1 to 9, characterized in that it comprises the steps of: - providing the fibrous reinforcement (3), - providing at least one identification support (2), - placing (130, 140) the fibrous reinforcement (3) and the identification support (2) in a mold (40), the identification support (2) being arranged at a distance from the fibrous reinforcement (3), - injection (150) of a matrix into the mold so as to simultaneously embed the fiber reinforcement (3) and the identification support (2), and - densification (160) so as to densify the matrix and the identification support (2) in the excess thickness (SE) of the matrix.

11. Manufacturing method according to the preceding claim, characterized in that it comprises a step of inserting a non-conductive positioning element (43) between the fibrous reinforcement (3) and the mold (40), the positioning element (43) carrying the identification support (2) and being arranged against the fibrous reinforcement (3).

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