Composite material part

Abstract

A composite material part includes a fiber preform forming fiber reinforcement including a stack of at least two fiber plies, each of the fiber plies being made of an interlock weave three-dimensional fabric and each of the fiber plies having a number of warp yarn layers or a number of weft yarn layers that is greater than or equal to three; and a matrix present in the pores of the fiber preform.

Claims

1. A composite material part comprising: a fiber preform forming fiber reinforcement comprising a stack of at least two fiber plies that are not woven together, each of the fiber plies being made of an interlock weave three-dimensional fabric and each of the fiber plies having a number of warp yarn layers or a number of weft yarn layers that is greater than or equal to three; and a matrix present in the pores of the fiber preform.

2. A part according to claim 1, wherein at least one of the stacked fiber plies includes yarns having different weights.

3. A part according to claim 1, wherein the number of stacked fiber plies is constant over the entire zone covered by the stack.

4. A part according to claim 1, wherein the number of stacked fiber plies varies over the zone covered by the stack.

5. A part according to claim 1, wherein the part constitutes an aeroengine casing.

6. A method of fabricating a part according to claim 1, the method comprising: forming a matrix in the pores of a fiber preform comprising a stack of at least two fiber plies that are not woven together, each of the fiber plies being made of an interlock weave three-dimensional fabric and each of the fiber plies having a number of warp yarn layers or a number of weft yarn layers that is greater than or equal to three.

7. A part according to claim 1, wherein each of the fiber plies has a number of warp yarn layers or a number of weft yarn layers that is greater than three.

8. A part according to claim 1, wherein at least one of the fiber plies presents both a number of warp yarn layers that is greater than or equal to three and a number of weft yarn layers that is greater than or equal to three.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics and advantages of the invention appear from the following description of particular embodiments of the invention given as non-limiting examples and with reference to the accompanying drawings, in which:

(2) FIG. 1 is a highly diagrammatic fragmentary view of a first example of a fiber preform suitable for constituting the fiber reinforcement of a part of the invention;

(3) FIG. 2 shows an interlock three-dimensional weave plane;

(4) FIG. 3 is a flow chart showing the various steps of a method of fabricating a composite material part of the invention; and

(5) FIG. 4 is a highly diagrammatic and fragmentary view of a second example of a fiber preform suitable for constituting the fiber reinforcement of a part of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) The field of application of the invention relates in particular to parts made of composite material and presenting a resin type matrix for composite materials that are used at relatively low temperatures, typically up to 300 C., or else of a refractory material such as carbon or a ceramic material when making thermostructural composites.

(7) FIG. 1 shows a stack 1 of three distinct fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 forming a fiber preform suitable for constituting the fiber reinforcement of an example part of the invention. Each of the fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 is made of interlock weave three-dimensional fabric and each of the fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 has a number of warp yarns or a number of weft yarns that is greater than or equal to three. It is possible that at least one of the fiber plies 2.sub.1, 2.sub.2, and 2.sub.3, and possibly each of them, presents both a number of warp yarn layers that is greater than or equal to three and a number of weft yarn layers that is greater than or equal to three. Advantageously, the fibers in each of the fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 may extend substantially in the same direction. A unidirectional fiber ply may optionally be present between two adjacent fiber plies 2.sub.1, 2.sub.2, and 2.sub.3. The fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 are not woven together. The fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 are not woven together over the entire width or over the entire length of the fiber preform. The fiber preform thus does not have any zone in which a layer of yarns from a first ply is woven together with a layer of yarns from a second ply that is distinct from the first ply. In particular, throughout the fiber preform, there is no layer of warp yarns of the first ply woven together with a layer of weft yarns of the second ply. Throughout the fiber preform, there is no layer of weft yarns of the first ply that is woven together with warp yarns of the second ply.

(8) As mentioned above, the stack 1, as shown, is made by superposing a plurality of fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 and, consequently, it is different from a stack obtained by rolling a single fiber ply.

(9) Each of the stacked fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 is made of interlock weave fabric. FIG. 2 is a view showing a plane of an interlock weave having seven warp yarns and eight weft yarns and that is suitable for making the stacked fiber plies 2.sub.1, 2.sub.2, and 2.sub.3. In the interlock weave shown, a weft layer T is made up of two adjacent weft half-layers t that are offset relative to each other in the warp direction. There are thus 16 weft half-layers in a staggered configuration. Each warp yarn links together three weft half-layers. It is also possible to adopt a weft configuration that is not staggered, the weft yarns of two adjacent weft layers being in alignment in the same columns. Suitable interlock type weaves are described in Document WO 2006/136755.

(10) By way of example, the fibers forming the stacked fiber plies may be made of ceramic material, e.g. of silicon carbide, of carbon, or of an oxide, e.g. of alumina. The fibers forming the stacked fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 may all be of the same chemical nature. In a variant, the stacked fiber plies 2.sub.1, 2.sub.2, and 2.sub.3 may include fibers of different chemical natures. In the example shown, the number of stacked fiber plies is constant over the entire zone covered by the stack, specifically three.

(11) The example shows a stack 1 having three stacked fiber plies 2.sub.1, 2.sub.2, and 2.sub.3. Naturally, it would not go beyond the ambit of the invention for the stack to have two fiber plies or more than three stacked fiber plies.

(12) FIG. 3 is a flow chart of an example method of fabricating a part of the invention. In a first step 10, at least two fiber plies are stacked, each of these fiber plies being made of an interlock weave three-dimensional fabric and each of these fiber plies having a number of warp yarn layers or a number of weft yarn layers that is greater than or equal to three. The stacked plies are not woven with one another. During step 10, the plies may be stacked in the dry state and they may be placed in a mold in order to shape the fiber preform. Under such circumstances, a resin is injected into the pores of the fiber preform during a step 20, the resin subsequently being polymerized during a step 30 by being subjected to heat treatment in order to form the matrix in the pores of the fiber preform. In a variant, it is possible to stack fiber plies that have already been pre-impregnated and to perform heat treatment in order to obtain a part of the invention.

(13) FIG. 4 shows a second example of a stack 1 of stacked fiber plies 2.sub.1, 2.sub.2, 2.sub.3, and 2.sub.4 forming a fiber preform suitable for constituting the fiber reinforcement of a part of the invention. The example stack 1 shown in FIG. 4 has a first region 3 of the stack with a number of stacked fiber plies (four fiber plies) that is different from the number of stacked fiber plies in a second region 4 of the stack where only three fiber plies are present. Such variations in the number of fiber plies in the stack 1 may serve to obtain local extra thickness, as shown.

(14) The term lying in the range . . . to . . . should be understood as including the bounds.