Fiber preform of π-shaped section, in particular for a fan platform made of composite material
View Patent ↗A fiber preform of π-shaped section, the preform including a base with a first face and an opposite second face, legs extending from the second face, and a fiber structure woven as a single piece by three-dimensional weaving with a plurality of layers of warp or weft yarns linked interlinked by weft or warp yarns in a plurality of layers of weft or warp yarns. In each plane of the preform, the weft or warp yarns of a first group of weft or warp yarns extend continuously through the base between two opposite edges thereof, and weft or warp yarns of a second group of weft or warp yarns extend continuously from an end of one of the legs to an end of the other leg, passing via the base, with the yarns of the first group and the yarns of the second group presenting two mutual crossings.
1. A fiber preform of π-shaped section, the preform comprising:
a base with a first face and an opposite second face;
legs extending from the second face;
a fiber structure woven as a single piece by three-dimensional weaving with a plurality of layers of warp yarns interlinked by weft yarns in a plurality of layers of weft yarns,
wherein in each weft plane of the fiber preform, the weft yarns of a first group of weft yarns extend continuously through the base between two opposite edges thereof, and weft yarns of a second group of weft yarns extend continuously from an end of one of the legs to an end of the other leg, passing via the base, each yarn of the second group crossing a plurality of yarns of the first group in only two distinct mutual crossing zones, each mutual crossing zone being located between two adjacent columns of warp yarns.
2. A preform according to claim 1 , wherein every weft yarn of the second group of weft yarns passes in depth via the base.
3. A preform according to claim 1 , wherein the crossings between the weft yarns of the first group and the weft yarns of the second group are situated close to the connections between the legs and the base.
4. A preform according to claim 1 , wherein, in each weft plane of the fiber preform, at least one weft yarn extends continuously from one edge to the other of the base, while remaining adjacent to the first face.
5. A preform according to claim 1 , wherein, in each weft plane of the fiber preform, at least one weft yarn extends continuously between the legs, while remaining adjacent to the second face.
6. A platform for a fan blade, the platform being made of a composite material comprising a fiber preform according to claim 1 densified by a matrix.
7. A fiber preform of π-shaped section, the preform comprising:
a base with a first face and an opposite second face;
legs extending from the second face;
a fiber structure woven as a single piece by three-dimensional weaving with a plurality of layers of weft yarns interlinked by warp yarns in a plurality of layers of warp yarns,
wherein in each warp plane of the fiber preform, the warp yarns of a first group of warp yarns extend continuously through the base between two opposite edges thereof, and warp yarns of a second group of warp yarns extend continuously from an end of one of the legs to an end of the other leg, passing via the base, each yarn of the second group crossing a plurality of yarns of the first group in only two distinct mutual crossing zones, each mutual crossing zone being located between two adjacent columns of weft yarns.
8. A preform according to claim 7 , wherein the crossings between the warp yarns of the first group and the warp yarns of the second group are situated close to the connections between the legs and the base.
9. A preform according to claim 7 , wherein, in each warp plane of the fiber preform, at least one warp yarn extends continuously from one edge to the other of the base, while remaining adjacent to the first face.
10. A preform according to claim 7 , wherein, in each warp plane of the fiber preform, at least one warp yarn extends continuously between the legs, while remaining adjacent to the second face.
11. A platform for a fan blade, the platform being made of a composite material comprising a fiber preform according to claim 7 densified by a matrix.