EP2089565B1 - 3d composite fabric - Google Patents

Abstract

Woven fabric comprises weft and warp fibers arranged in a structure with a base unit comprising 28 weft fibers forming 8 parallel columns and 12 warp fibers arranged in four parallel staggered planes. Woven fabric comprises weft and warp fibers arranged in a structure with a base unit comprising 28 weft fibers forming 8 parallel columns, in which columns 1, 3, 5 and 7 each comprise four fibers and columns 2, 4, 6 and 8 each comprise three fibers, where the columns are equally spaced and the weft fibers extend in seven levels transverse to the columns; and 12 warp fibers arranged in four parallel staggered planes, namely a first plane in which a first warp fiber passes over the first weft fiber of column 1, under the second weft fiber of column 5 and over the first weft fiber of column 1 in the next unit, and second and third warp fibers extend parallel to the first warp fiber; a second plane in which a first warp fiber extends parallel to the seven levels and passes above the first weft fiber of columns 2, 4, 6 and 8 and under the first weft fiber of columns 1, 3, 5 and 7; a third plane in which three warp fibers extend parallel to the warp fibers of the first plane; and a fourth plane in which three warp fibers extend parallel to the warp fibers of the second plane so that they pass under the weft fibers of columns 2, 4, 6 and 8. An independent claim is also included for a part produced from a fabric as above.

Description

The invention relates to a 3D composite fabric.

BACKGROUND OF THE INVENTION

The present invention relates to an optimized reinforcement fabric, of the multiply bonded type, which can be used for the production of composite material parts which are highly stressed in tension, compression or bending, and / or subjected to impacts. Among such parts, one can for example quote the landing struts.

Textile structures known as 1D or 2D are known depending on whether their fibers extend in a single direction or in two different directions. These structures, in general, do not make it possible to respond effectively to the aforementioned requests. The so-called 3D structures, comprising fibers extending in three distinct directions in space, are better able to respond to said stresses. We know that there exist structures called 4D, 5D, 9D, 11D ... with fibers extending in a larger number of distinct directions, but these structures are very complex and their production is difficult to automate.

The invention therefore relates more particularly to 3D textile structures.

Among these, there are known 3D structures comprising a plurality of layers linked by connection points. These structures are known to have good linearity when bending the weft fibers, and offer the advantage of having reinforcements. However, this binding method does not give the piece produced from such a fabric good impact resistance.

Woven fabric is also known to be woven, the orthogonal 3D fabric (in which the ply-bonding fibers extend substantially orthogonally to the plies) being the one having the best linearity (i.e., a path with small bond angles or inflections) of the weft fibers and the warp fibers , and that resists compression well. However, in order for this fabric to have a fiber volume fraction of interest, it must be compressed so that the orthogonal wires at the folds used to connect them acquire sharp inflections giving them a very undulating and therefore not very linear path, which does not does not contribute effectively to the transfer of effort.

Although in this respect non-orthogonal 3D fabrics are more interesting, they nevertheless have the drawback of having binding fibers having binding angles or inflections that are too great, that the reinforcement of the fabric is simple, type taffeta, satin or twill multiply, or that the frame is more elaborate, as the frame type 3X.

The fabric known as "2,5D", described in the document FR 2,610,951 , particularly optimized, has low expansion and a high percentage of occupied area, but at the expense of low linearity (i.e. at least some of the fibers have significant inflections or binding angles). The definition of this fabric gives it angular characteristics detrimental to impact resistance and limits reversible textile structures (obtained by rotating the frame at 90 degrees) to low density structures, unless a high number of plies added, which makes it difficult to automate.

As for the fabric described in the document US5899241 ( EPO856601 A1 ), it is particularly optimized for impact resistance. However, the high level of interleaving between the pleats limit the compressive strength of an element made from such a fabric.

OBJECT OF THE INVENTION

The subject of the invention is a process for weaving an optimized 3D fabric having good resistance, in particular to impacts, while being easily deformable.

DESCRIPTION OF THE INVENTION

• au moins vingt-huit fibres de trame (vues en bout), numérotées 1 à 28, disposées en quinconce et formant 8 colonnes C1...C8 qui s'étendent perpendiculairement à une épaisseur du tissu, et qui comportent alternativement quatre et trois fibres de trame en étant séparées d'un même espace prédéterminé P, les fibres de trame s'étendant dans sept niveaux N1...N7 qui s'étendent transversalement aux colonnes. Ainsi, les première, troisième, cinquième et septième colonnes C1,C3,C5,C7 comportent quatre fibres de trame, s'étendant respectivement dans les niveaux N1,N3,N5 et N7, tandis que les deuxième, quatrième, sixième et huitième colonnes C2,C4,C6,C8 comportent trois fibres de trame s'étendant respectivement dans les niveaux N2,N4,N6;
• au moins douze fibres de chaîne A...L disposées dans au moins quatre plans parallèles s'étendant transversalement aux fibres de trame, chacun de ces plans contenant au moins trois fibres de chaîne parallèles disposées les unes au dessus des autres de la façon suivante.

The invention will be directly described with reference to the single appended figure showing a basic pattern of the fabric according to a particular embodiment of the invention, in which the weft fibers are represented at the end and the warp fibers extend. in planes parallel to the plane of the figure. The fabric here comprises a basic pattern comprising:

• at least twenty-eight weft fibers (end views), numbered 1 to 28, staggered and forming eight columns C1 ... C8 which extend perpendicular to a thickness of the fabric, and which alternately comprise four and three fibers with the weft being separated from the same predetermined space P, the weft fibers extending in seven levels N1 ... N7 which extend transversely to the columns. Thus, the first, third, fifth and seventh columns C1, C3, C5, C7 comprise four weft fibers, respectively extending in the levels N1, N3, N5 and N7, while the second, fourth, sixth and eighth columns C2, C4, C6, C8 comprise three weft fibers extending respectively in the N2, N4, N6 levels;
• at least twelve A ... L chain fibers arranged in at least four parallel planes extending transversely to the weft fibers, each of these planes containing at least three parallel chain fibers arranged one above the other as follows .

In a first plane which coincides with the plane of the figure, the relevant warp fibers A, B, C, are represented in solid lines. The warp fiber A passes over the first weft fiber 1 of the first column C1, passes under the second weft fiber 16 of the fifth column C5, passes over the first weft fiber 1 of the first column C1 of the following pattern. In this same plane, the warp fiber B and the warp fiber C are parallel to the warp fiber A, but are shifted according to the fabric thickness of one weft fiber each time.

• dans un troisième plan qui est ici en arrière du deuxième plan, les fibres de chaîne G,H,I sont représentées en traits interrompus mixtes. Elles suivent un chemin parallèle à celui des fibres de chaîne A,B,C du premier plan, mais elles sont décalées latéralement, selon une direction parallèle aux niveaux, de quatre colonnes ;
• enfin, dans un quatrième plan qui est ici en arrière du troisième plan, les fibres de chaîne J,K,L sont représentées en traits pointillés. Elles sont parallèles aux fibres de chaîne D,E,F, mais sont décalées selon l'épaisseur du tissu de sorte que la fibre de chaîne J passe sous la première fibre de trame 5 de la deuxième colonne, la fibre de chaîne K passe sous la fibre de trame 6 de cette même colonne, et la fibre de chaîne .L passe sous la fibre de trame 7 de cette même colonne.

In a second plane which is here behind the foreground, the warp fibers are substantially parallel to the levels N1 ... N7 and are represented in broken lines. The warp fiber D passes over the first weft fiber 5 of the second column C2, below the first weft fiber 8 of the third column C3, above the first weft fiber 12 of the fourth column C4 , And so on. The E and F warp fibers follow a parallel path, being shifted in a direction parallel to the columns of one weft fiber each time;

• in a third plane which is here behind the second plane, the warp fibers G, H, I are represented in broken lines. They follow a path parallel to that of the warp fibers A, B, C in the foreground, but they are shifted laterally, in a direction parallel to the levels, of four columns;
• finally, in a fourth plane which is here behind the third plane, the warp fibers J, K, L are represented in dashed lines. They are parallel to the warp fibers D, E, F, but are shifted according to the thickness of the fabric so that the warp fiber J passes under the first weft fiber 5 of the second column, the warp fiber K passes under the weft fiber 6 of the same column, and the warp fiber L passes under the weft fiber 7 of this same column.

• elle permet d'obtenir une structure multiplis ayant un degré de liaison adapté à fournir une bonne résistance à la délamination, et, partant, une meilleure résistance aux impacts et à la compression, tout en préservant une bonne déformabilité ;
• ce tissu peut est fabriqué à partir de fibres de carbone, mais également de fibres de verre, de fibres d'aramide, ou encore de fibres silicées ou céramiques. Il constitue avantageusement une préforme qui peut être imprégnée de résine par exemple par le procédé RTM (Resin transfer moulding) après mise en forme de la préforme dans un moule ou tout autre procédé ;
• ce tissu permet le tissage automatisé de fibres qui ont des performances mécaniques importantes (par exemple des fibres de carbone à haut module d'élasticité), mais qui sont fragiles au tissage. Il est même possible d'utiliser des fibres de carbone ayant une densité linéaire importante, telle que des fibres à 48 ou 96 kilofilaments, voire plus ;
• le tissu ainsi obtenu présente une fraction volumique de fibres importante, au moins égale ici à 57% ;
• la disposition des fibres de chaîne en plusieurs plans décalés induit des angles de liaison θ assez faibles, en pratique inférieurs ou égal à 15°, ce qui confère aux fibres de trame et aux fibres de chaîne une très bonne linéarité qui permet de faire travailler plus efficacement les fibres en compression ;
• cette disposition permet de déséquilibrer la proportion de fibres de chaîne par rapport à la proportion de fibres de trame pour compenser la non-linéarité de ces dernières (par exemple 70% de fibres de trame pour 30% de fibres de chaîne) ;
• enfin, cette disposition peut être renversée (en tournant l'armature de 90°) pour en améliorer la linéarité.

This provision offers several advantages:

• it makes it possible to obtain a multiply structure having a degree of connection adapted to provide good resistance to delamination, and hence better resistance to impact and compression, while preserving good deformability;
• this fabric can be made from carbon fibers, but also from glass fibers, aramid fibers, or even silica or ceramic fibers. It is advantageously a preform that can be impregnated with resin for example by the RTM (Resin transfer molding) process after forming the preform in a mold or any other process;
• this fabric allows the automated weaving of fibers which have important mechanical performances (for example carbon fibers with high modulus of elasticity), but which are fragile to the weaving. It is even possible to use carbon fibers having a large linear density, such as fibers with 48 or 96 kilofilaments, or more;
• the fabric thus obtained has a significant volume fraction of fibers, at least 57% in this case;
• the arrangement of the warp fibers in several shifted planes induces relatively low bond angles θ, in practice less than or equal to 15 °, which gives the weft fibers and the warp fibers a very good linearity which makes it possible to work more effectively the fibers in compression;
• this arrangement makes it possible to unbalance the proportion of warp fibers with respect to the proportion of weft fibers to compensate for the non-linearity of these fibers (for example 70% of weft fibers for 30% of chain fibers);
• finally, this arrangement can be reversed (turning the armature by 90 °) to improve the linearity.

The invention is not limited to what has just been described, but on the contrary encompasses any variant within the scope defined by the claims.

In particular, the basic pattern of the fabric reinforcement described here can be easily extended, both in the direction of the thickness of the fabric (hence in the direction of the columns), and in the lateral direction (so in the direction of levels).

Claims (4)

1. A fabric of woven yarns or fibers comprising weft fibers and warp fibers disposed in a weave having a base pattern that comprises:

   · at least twenty-eight weft fibers (1...28), disposed in a staggered configuration and forming eight parallel columns (C1...C8), in which each of the first, third, fifth, and seventh columns has four weft fibers and each of the second, fourth, sixth, and eighth columns has three weft fibers, the columns being separated by a common predetermined space (P), and the weft fibers (1...28)extending in seven levels (N1...N7) that extend transversely to the columns;

   · at least twelve warp fibers (A...L) disposed in at least four parallel planes extending transversely to the weft fibers and offset from one another; characterized in that each of these planes contains at least three parallel warp fibers disposed one above another as follows:

   · in a first plane, a first warp fiber (A) passes over the first weft fiber (1) of the first column (C1), passes under the second weft fiber (16) of the fifth column (C5), and then passes over the first weft fiber (1) of the first column (C1) of the following pattern; the second and third warp fibers (B, C) extending in said first plane parallel to the first weft fiber (A), being offset on each occasion by one weft fiber in a direction parallel to the columns;

   · in a second plane, a first warp fiber (D) extends substantially parallel to the levels (N1...N7) passes over the first weft fiber (5) of the columns (C2, C4, C6, C8) having three weft fibers, and under the first weft fiber of the columns (C1, C3, C5, C7) having four weft fibers; the second and third warp fibers (E, F) extending parallel to the first warp fiber (D), being offset on each occasion by one weft fiber in a direction parallel to the columns;

   · in a third plane, the three the warp fibers concerned (G, H, I) extend parallel to the warp fibers (A, B, C) of the first plane, being offset laterally by four columns in a direction parallel to the levels; and finally

   · in a fourth plane, the three warp fibers (J, K, L) concerned extend parallel to the warp fibers (D, E, F) of the second plane, being offset in a direction parallel to the columns in such a manner that they pass under the weft fibers of the columns (C2, C4, C6, C8) having three weft fibers.
2. A fabric according to claim 1, having a fiber volume fraction of not less than 57%.
3. A fabric according to claim 1, wherein the fibers have linking angles (θ) less than or equal to 15°.
4. A part obtained from the fabric of claim 1.

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