Composite material part incorporating a layer of elastomer, housing and vehicle comprising such a part.

Abstract

Composite material part comprising at least a first layer (11) of composite material and a second layer (12) of composite material, said layers each comprising reinforcing fibers (14) embedded in an organic matrix (15), characterized in that the part comprises at least a third layer (13), made of elastomer, extending between the two layers (11, 12) of composite material and mechanically bonding the two layers (11, 12) of composite material to each other. Housing and vehicle incorporating such a part. FIGURE OF THE ABSTRACT: Fig. 1

Description

Title of the invention: Part of composite material incorporating a layer of elastomer, housing and vehicle comprising such a part.

[0001] The present invention relates to the field of composite materials, in particular organic matrix composites (or OMCs), and objects manufactured in whole or in part from composite materials.

[0002] BACKGROUND OF THE INVENTION

[0003] A composite material generally comprises reinforcing fibres embedded in a matrix: the fibres mainly contribute to the mechanical strength of the material and the matrix provides the material with its cohesion and shape. The matrix also has the function of protecting the fibres from external aggressions. Composite materials have relatively high mechanical performance in relation to their density and are therefore most often used to produce parts that must withstand mechanical stress while being relatively light.

[0004] There are short fiber composite materials and long fiber composite materials. The fibers are positioned so as to extend in the appropriate direction to absorb the forces to which the composite material part will be subjected. Depending on the parts, there may be a unidirectional orientation of the fibers or a multidirectional orientation depending on the direction of the forces that said parts will have to undergo in use. To obtain a multidirectional orientation, one generally uses either a fabric in which the fibers extend in at least two directions while intersecting or unidirectional layers of fibers that are stacked on top of each other in such a way that the direction of the fibers changes from one layer to another.

[0005] In the case of CMOs, the matrix is ​​made of organic, thermoplastic or thermosetting polymer resin. The fibers are made of any material capable of providing the CMO with the mechanical properties required for the intended application, for example glass, carbon or aramid.

[0006] Devices are also known in which a part is mounted in a frame subjected to vibrations which are transmitted to the part in question. If the transmission of these vibrations is detrimental to the operation of the device (high frequency vibrations, for example, cause disturbances in certain electronic equipment), it is known to fix the part to the frame using elastic suspension elements, such as elastomer blocks, which will absorb all or part of said vibrations. However, these elastic suspension elements have a mass and a size which can be detrimental in certain applications, particularly for aeronautical applications. In addition, the addition of these elements generates additional costs.

[0007] Such elastic suspension elements are found, for example, in the mountings of inertial unit housings in vehicles.

[0008] SUBJECT OF THE INVENTION

[0009] The invention aims in particular to provide a means for limiting the transmission of vibrations. Summary of the invention

[0010] To this end, according to the invention, a composite material part is provided comprising at least a first layer of composite material and a second layer of composite material. Said layers each comprise reinforcing fibers embedded in an organic matrix. The part comprises at least a third layer, made of elastomer, extending between the two layers of composite material and mechanically bonding the two layers of composite material to each other.

[0011] Thus, the composite material part offers the mechanical performance of the composite material but has an internal structure containing a layer of elastomer. By elastomer, we mean any polymer having elastic properties, whether natural or synthetic, thermoplastic or thermosetting. As a result, the elastomer layer will limit if not prevent the propagation of vibrations in the composite material part and the composite material part will thus provide an additional vibration damping function while maintaining a relatively low mass and volume.

[0012] According to optional characteristics, used individually or in whole or in part in combination: - at least one of the two layers of composite material comprises a stack of sub-layers in which the reinforcing fibers extend in an orientation which possibly changes from one sub-layer to another; - the matrix is ​​a thermoplastic resin; - the thermoplastic resin is based on one of the following polymers: polyphenylene sulfide, polyetheretherketone, etc. - the matrix is ​​a thermosetting resin; - the thermosetting resin is based on one of the following polymers: polyepoxide, polyphenol, polyimide, polybismaleimide, polyester, polyvinylester, etc.; - the reinforcing fibers are based on carbon, glass, aramid, etc.; - the elastomer is based on one of the following polymers: polymer of silicone, polyisoprene, ethylene-propylene-diene...

[0013] The invention also relates to a housing of which at least one wall is formed from such a part.

[0014] The invention finally relates to a vehicle having a structure equipped with such a housing, the part being fixed to the structure of the vehicle.

[0015] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention. Brief description of the drawings

[0016] Reference will be made to the accompanying drawings, among which:

[0017] [Fig-1] [Fig. 1] is a partial schematic view of a housing installed in a vehicle in accordance with the invention;

[0018] [Fig.2] [Fig.2] is a partial schematic view, in cross-section, of the area II of [Fig.l];

[0019] [Fig.3] [Fig.3] is a partial schematic detail view of zone III of the [Fig.2], DETAILED DESCRIPTION OF THE INVENTION

[0020] With reference to the figures, the invention is described here in application to a housing, generally designated 1, fixed to a structure S of a vehicle V such as an aircraft.

[0021] The housing 1 comprises two half-shells 10 (designated individually by “.1” and “.2” in [Fig.l]) which are fixed to a metal belt 20 to delimit a cavity containing here an inertial unit but which can contain anything else and for example a computer, an optronic device such as a sight or a shooting scope, or other.

[0022] With particular reference to Figures 2 and 3, each half-shell 10 is formed from a piece of composite material which comprises: - a first layer 11 in composite material, - a second layer 12 in composite material, - a third layer 13 in elastomer.

[0023] The third layer 13 extends between the two layers 11, 12 and mechanically bonds the two layers 11, 12 to each other. The layer thus has a first main face 11a extending flat against a first main face 13a of the third layer 13 and, opposite, a second free main face 11b. The layer 12 thus has a first main face 12a extending flat against a second main face 13b of the third layer 13 and, opposite, a second free main face 12b. It is understood that the layer 13 ensures the attachment of the layer 11 to the layer 12 (the three layers form a unitary assembly).

[0024] Each layer 11, 12 comprises reinforcing fibers 14 embedded in an organic matrix 15 (shown schematically in [Fig.3]).

[0025] More precisely, the layer 11 comprises a stack of sub-layers 11' (also called plies), here eight in number, in which the reinforcing fibers 14 extend parallel to the main faces 11a, 11b in different orientations. For example, the reinforcing fibers 14 extend in the following orientations, from the first face 11a to the second face 11b: 90°, 0°, -45°, 45°, 45°, -45°, 0°, 90°. It is therefore understood that, for certain adjacent sub-layers 11', the orientation of the fibers changes from one sub-layer 11' to another.

[0026] Symmetrically, the layer 12 comprises a stack of sub-layers 12', here eight in number, in which the reinforcing fibers extend parallel to the main faces 12a, 12b in different orientations. For example, the reinforcing fibers 14 extend in the following orientations, from the first face 12a to the second face 12b: 90°, 0°, -45°, 45°, 45°, -45°, 0°, 90°. It is therefore understood that, for certain adjacent sub-layers 12', the orientation of the reinforcing fibers 14 changes from one sub-layer 12' to another.

[0027] This arrangement of the reinforcing fibers 14 is quasi-isotropic with regard to the mechanical properties, as are those of a molded metal part.

[0028] In each layer 11, 12, the organic matrix 15 is a thermoplastic resin based on one of the following polymers: polyphenylene sulfide, polyetheretherketone, etc. Alternatively, the organic matrix 15 is a thermosetting resin based on one of the following polymers: polyepoxide, polyphenol, polyimide, polybismaleimide, polyester, polyvinylester, etc.

[0029] In each layer 11, 12, the reinforcing fibers 14 are for example based on carbon, glass, or aramid.

[0030] The elastomer of layer 13 is for example based on one of the following polymers: silicone polymer, polyisoprene, ethylene-propylene-diene.

[0031] As an example for the present application, the following materials are chosen: - polyepoxide matrix, - carbon fiber, - synthetic rubber elastomer such as that produced under the SMACTANE brand by the company SMAC sas.

[0032] The sub-layers 11', 12' have for example a thickness of approximately 0.3 mm, the layer 13 here has a thickness of between approximately 2 and 3 mm. Other thicknesses can of course be used depending on the constraints encountered in the envisaged application.

[0033] In each piece of composite material of the present embodiment, the layers 11, 12 comprise the same number of sub-layers 11', 12' arranged symmetrically and they are made of the same material.

[0034] Furthermore, in the present embodiment, the layers 11, 12, 13 of the composite material part of the half-shell 10.1 are identical to the layers 11, 12, 13 of the composite material part of the half-shell 10.2. Alternatively, the number of sub-layers 11', 12' and / or the materials of the layers 11, 12, 13 could be different between the composite material part of the half-shell 10.1 and the composite material part of the half-shell 10.2.

[0035] The composite material parts of the half-shells 10.1, 10.2 are produced by manual draping: the sub-layers 11' are produced successively on top of each other by arranging the reinforcing fibers 14 pre-impregnated with the resin forming the matrix 15 to constitute the layer 11. The layer 13 is deposited on the layer 11 in the form of a film and then the layer 12 is formed like the layer 11. A co-curing under vacuum in an autoclave is then carried out. This is a particular manufacturing method and others can be used such as thermocompression or resin transfer molding. It is for example possible to interpose an adhesion layer between the layer 13 and the layers 11 and 12, to provide for cleaning of the main surfaces in contact with each other (acetone / alcohol cleaning, plasma, etc.) or shot-blasting of said main surfaces.

[0036] Each piece of composite material is here arranged to absorb at least part of the vibrations in the frequency range above 5000 Hz, for example in application to an inertial unit housing.

[0037] It can be seen in [Fig. 2] that the piece of composite material of the half-shell 10.1 is pierced with a hole 16 in which extends a tubular insert 17 receiving a bolt 30 also passing through the structure S to connect, here rigidly, the piece of composite material of the half-shell 10.1 to the structure S. It is possible to coat the wall of the hole 16 with the elastomer of the layer 13 to also limit the transmission of vibrations between the bolt 30 and the piece of composite material.

[0038] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0039] In particular, the third layer 13 may comprise one or more elastomers.

[0040] Several superimposed layers of elastomer may extend between two layers of composite material.

[0041] The composite material part may comprise a third layer of composite material and a second layer of elastomer for bonding the third layer of composite material to one of the other two layers of composite material, or even a greater number of layers of composite material and layers of elastomer.

[0042] The number of sub-layers in the first layer of composite material may be different from the number of sub-layers in the second layer of composite material.

[0043] The choice of the number of underlayers, the orientation and material of the fibers, the matrix resin, the elastomer is determined according to the mechanical stresses that the part is intended to withstand and the environment of the part in use (temperature, ultraviolet radiation, humidity, chemical attacks, etc.). It is also possible to provide for a portion of the fibers to extend perpendicular to the main surfaces.

[0044] Although the number of sub-layers of the first piece of composite material is here identical to the number of sub-layers of the second piece of composite material, these numbers may be different.

[0045] The housing may comprise only parts of composite material according to the invention or may comprise one or more parts of composite material according to the invention assembled with parts of traditional composite material or metal or ceramic or other.

[0046] The piece of composite material according to the invention can be used to form one or more walls of a housing as in the embodiment described but also any other object arranged in a vibration transmission path.

[0047] The composite material part may have a shape other than that described and for example a flat, dihedral, curved shape, etc. The person skilled in the art will choose the manufacturing method most suited to the part he wishes to produce.

[0048] The invention can be used on any type of vehicle, land, air, space, nautical, etc.

Claims

Claims

1. A part of composite material comprising at least a first layer (11) of composite material and a second layer (12) of composite material, said layers each comprising reinforcing fibers (14) embedded in an organic matrix (15), characterized in that the part comprises at least a third layer (13), of elastomer, extending between the two layers (11, 12) of composite material and mechanically bonding the two layers (11, 12) of composite material to each other.

2. Part according to claim 1, in which at least one of the two layers (11, 12) of composite material comprises a stack of sub-layers (11', 12') in which the reinforcing fibers extend in an orientation which possibly changes from one sub-layer to another.

3. A part according to claim 1 or 2, wherein the matrix (15) is a thermoplastic resin.

4. Part according to claim 3, in which the thermoplastic resin is based on one of the following polymers: polyphenylene sulfide, polyetheretherketone, etc.

5. A part according to claim 1 or 2, wherein the matrix (15) is a thermosetting resin.

6. Part according to claim 5, in which the thermosetting resin is based on one of the following polymers: polyepoxide, polyphenol, polyimide, polybismaleimide, polyester, polyvinylester.

7. Part according to any one of the preceding claims, in which the reinforcing fibers (14) are based on carbon, glass, aramid.

8. Part according to any one of the preceding claims, in which the elastomer is based on one of the following polymers: silicone polymer, polyisoprene, ethylene-propylene-diene.

9. Housing comprising at least one wall (10.1, 10.2) formed from a piece according to any one of the preceding claims.

10. A housing according to claim 9, wherein the part has an at least partially shell shape.

11. Vehicle (V) having a structure (S) equipped with a housing according to claim 8 or 9, the part being rigidly fixed to the structure of the vehicle.

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