REINFORCING TEXTILE STRUCTURE FOR COMPOSITE MATERIALS

Abstract

A reinforcing textile complex for composite materials, comprising a stack of textile layers with a view to their impregnation by a polymer resin, the including complex comprising: an assembly of weft threads (2); an assembly of warp threads (3, 4) associated in pairs, each pair comprising two threads of different type, at least one of which (3) is based on high toughness threads, the two threads of a given pair being woven with the weft threads in a leno weave.

Claims

1-11. (canceled)

12. A textile reinforcement complex for composite materials, comprising: a stack of textile layers with a view to their impregnation by a polymer resin, the stack comprising an intermediate layer (1) comprising: an assembly of weft yarns (2); and an assembly of warp yarns (3, 4) associated in pairs, each pair comprising two yarns of different type, one (3) at least of which is based on high-tenacity yarns, the two yarns of a same pair being woven with the weft yarns in a leno weave, wherein said intermediate layer (1) has a draining role within the complex.

13. The complex of claim 12, wherein the weft yarns (2) of the intermediate layer (1) are based on high-tenacity yarns.

14. The complex of claim 12, wherein: the warp yarns (3, 4) comprise warp yarns (3) of a first type and warp yarns (4) of a second type; and the warp yarns (3) of the first type have a higher count than the warp yarns (4) of the second type.

15. The complex of claim 14, wherein the warp yarns (4) of the second type are based on organic synthetic yarns.

16. The complex of claim 14, wherein the warp yarns (4) of the second type are based on high-tenacity yarns.

17. The complex of claim 12, wherein the mass per unit area of the weft yarns (2) of the intermediate layer is substantially equal to the mass per unit area of the warp yarns (3, 4).

18. The complex of claim 12, wherein: the warp yarns (3, 4) comprise warp yarns (3) of a first type and warp yarns (4) of a second type; a mass per unit area of the warp yarns (3) of the first type is more than three times greater than that of the warp yarns (4) of the second type.

19. The complex of claim 12, wherein: the warp yarns (3, 4) comprise warp yarns (3) of a first type and warp yarns (4) of a second type; a mass per unit area of the warp yarns (3) of the first type is more than four times greater than that of the warp yarns (4) of the second type.

20. The complex of claim 12, wherein the gap between at least one of the weft or the warp yarns is between two and three times a width of a single weft yarn.

21. The complex of claim 12, wherein the gap between at least one of the weft or warp yarns is greater than four times a width of a single weft yarn.

22. The complex of claim 12, further comprising at least one layer formed by a mat of fibers, in contact with the intermediate layer.

23. The complex of claim 22, wherein the layer formed by the mat of fibers is made of a material identical to that of the reinforcement layers.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] The way to implement the present invention, as well as the resulting advantages, will better appear from the description of the following embodiments, in relation with the accompanying drawings.

[0039] FIG. 1 is a top view of a textile structure forming the intermediate draining layer of a complex according to the invention.

[0040] FIGS. 2 and 3 are cross-section views respectively along planes II-II and III-III of FIG. 1.

[0041] FIG. 4 is a cross-section view of a complex according to the invention, including the intermediate layer of FIG. 1.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0042] Generally, the draining and structuring intermediate layer, such as illustrated in FIG. 1, comprises weft yarns 2 and warp yarns 3, 4. Weft yarns 2 are arranged parallel to one another and have almost no crimp. Warp yarns 3, 4 are associated in pairs.

[0043] The weaving is performed by using a leno weave between the two weft yarns 4 and 3 on the one hand, and weft yarn 2 on the other hand. The two warp yarns 3, 4 are interlocked around the frame.

[0044] Due to the tension difference between the two warp yarns, and to their count difference, a configuration where warp yarns 3 of the first type rest on the ply of weft yarns 2 is obtained. Each warp yarn 4 of the second type thus passes under a weft yarn 2 and over warp yarn 3, alternately on one side and the other of the main warp yarn 3 associated therewith.

[0045] Thus, as illustrated in FIG. 2, the main warp yarns 3 are all arranged on the same side as the ply of weft yarns 2, and the warp yarns 4 of the second type, that is, of lowest count, run from one surface to the other of the structure with a significant crimp.

[0046] Of course, the proportions of the different yarns illustrated in the drawings are given as an example only, and the various yarns may differ in reality from this representation.

[0047] It is further possible to modify the number of yarns per length unit, in the warp direction and in the weft direction to adjust the mechanical properties of the future reinforcement as well as the resin flow capacity.

[0048] Different practical embodiments have thus been formed.

EXAMPLE 1

[0049] weft yarn 2: a 1,200-tex glass yarn, with a 468-g/m.sup.2 mass per unit area;

[0050] warp yarn 3 of the first type: a 1,200-tex glass yarn, with a 438-g/m.sup.2 mass per unit area;

[0051] warp yarn 4 of the second type: a 28-tex polyester yarn, with a 16-g/m.sup.2 mass per unit area;

[0052] 1-mm gap between weft yarns

[0053] gap between warp yarns: repeated pattern with two yarns separated by 4 mm and then 4 yarns separated by from 0.5 to 0.7 mm.

EXAMPLE 2

[0054] weft yarn 2: a 600-tex glass yarn, with a 240-g/m.sup.2 mass per unit area;

[0055] warp yarn 3 of the first type: a 600-tex glass yarn, with a 240-g/m.sup.2 mass per unit area;

[0056] warp yarn 4 of the second type: a 28-tex polyester yarn, with a 20-g/m.sup.2 mass per unit area;

[0057] gap between weft yarns: 1.5 mm (approximately)

[0058] gap between warp yarns: 1.5 mm (approximately)

EXAMPLE 3

[0059] weft yarn 2: a 600-tex glass yarn, with a 276-g/m.sup.2 mass per unit area;

[0060] warp yarn 3 of the first type: a 1,200-tex glass yarn, with a 280-g/m.sup.2 mass per unit area;

[0061] warp yarn 4 of the second type: a 28-tex polyester yarn, with a 8-g/m.sup.2 mass per unit area;

[0062] In this example, weft glass yarns 2 are thinner, but are arranged with a smaller pitch, to form a gap in the order of one millimeter, corresponding to the width of a weft yarn.

EXAMPLE 4

[0063] weft yarn 2: a 600-tex glass yarn, with a 276-g/m.sup.2 mass per unit area;

[0064] warp yarn 3 of the first type: a 600-tex glass yarn, with a 240-g/m.sup.2 mass per unit area;

[0065] weft yarn 4 of the second type: a 28-tex polyester yarn, with a 18-g/m.sup.2 mass per unit area.

[0066] gap between weft yarns: 1 mm

[0067] gap between warp yarns: 1.5 mm

[0068] The properties of these different examples have been measured in comparison with a reference complex, constructed according to the teachings of patent FR 2870861, comprising two reference reinforcing layers formed of a 500-g/m.sup.2 glass fabric, and a reference draining core formed of a warp knitting based on a 110-dtex polyester yarn, having a 110-g/m.sup.2 general weight.

[0069] The performances of these four examples may be summed up in the following table:

TABLE-US-00001 Reinforcing construction Front infusion ID permeability Mechanical properties * (g/m.sup.2) Glass tx Permeability Thickness traction 0 Total 0 90 By volume K0 Laminate E weight warp weft (%) (m.sup.2) (mm) (MPa) (GPa) Reference 482 236 236 45 6.86 .Math. 10.sup.11 1.72 276.3 17.6 reinforcing layer Reference draining 110 / / / 7.13 .Math. 10.sup.9 2.87 96 7.9 core Reference complex 620 265 240 19 2.10 .Math. 10.sup.9 4.39 243 12.4 Example Nr 1 916 432 468 39 2.71 .Math. 10.sup.9 2.76 Example Nr 2 502 240 240 32 3.43 .Math. 10.sup.9 2.65 234.5 14.3 Example Nr 3 564 288 275 34 2.98 .Math. 10.sup.9 3.21 212.8 14.9 Example Nr 4 536 240 276 34 3.74 .Math. 10.sup.9 2.62 * the mechanical tests are carried out with an identical standard stack (mat + Product to be tested + mat)

[0070] Permeability is a physical characteristic which designates the ability of a material to allow the transfer of fluid through a connected network. Darcy's law enables to link a flow rate to a pressure gradient applied to the fluid due to a characteristic parameter of the medium which is crossed, that is, permeability k.

[0071] Darcy's law can be expressed as:

[00001]$k=\frac{Q}{S}\frac{.Math..Math.L}{.Math..Math.P}$

[0072] where: [0073] k is the permeability (in m.sup.2), [0074] Q is the flow rate through the test piece (in m.sup.3/s), [0075] S is the cross-section of the test piece (in m.sup.2), [0076] is the dynamic viscosity of the fluid (in Pa.Math.s) [0077] P is the pressure drop measured between the ends of the test piece (in Pa) [0078] and L, the length of the test piece

[0079] The permeability can be measured along 3 axes. The permeability indicated in the above table corresponds to the permeability measured in the plane of the reinforcement, along the warp direction.

[0080] The draining properties of this characteristic layer can be expressed in complexes used to manufacture composite parts. Such complexes include a plurality of reinforcing layers selected for their mechanical properties. Thus, as schematically illustrated in FIG. 4, draining layer 1 may be integrated within a stack of a plurality of reinforcing layers 11-16 formed by weaving of warp yarns 20 and weft yarns 21, and having numbers and orientations determined according to the general mechanical properties desired for the final composite part.

[0081] There appears from the foregoing that the reinforcement structure according to the invention enables to combine structural reinforcement properties with a good permeability, thus providing a draining structural reinforcement.