Abstract: The preform made of a 3D fibrous structure comprises at least 3 layers (1, 2) of weft yarns and/or warp yarns, the structure being woven as a single part by multilayer weaving between a plurality of layers of warp yarns and a plurality of layers of weft yarns. It comprises a predetermined distribution of points of intersection of warp yarn and weft yarn that are bonded by polymer. The polymer represents a mass of less than or equal to 10%. The preform comprises at least one thermoformed portion in which the warp yarns and the weft yarns are bonded at the intersections thereof by polymer where at least one of the warp and/or weft yarns bears polymer.

Abstract: Said preform (3) defining two parts (21, 23) and comprising: a first group (C1) of layers of warp yarns, which is external in the first part, a second group (C2) of layers of warp yarns immediately beneath said first group, and a first group (T1) of layers of weft yarns which is external in the first part. Furthermore, the first group of layers of warp yarns is absent in the second part and the first group of layers of weft yarns (19) extends into the second part, the first group of layers of weft yarns being external in the second part. The yarns of the first weft group have a lower yarn count than the yarns of the second weft group; and/or the yarns of the first warp group have a lower yarn count than the yarns of the second warp group.

Abstract: The preform made of a 3D fibrous structure comprises at least 3 layers (1, 2) of weft yarns and/or warp yarns, the structure being woven as a single part by multilayer weaving between a plurality of layers of warp yarns and a plurality of layers of weft yarns. It comprises a predetermined distribution of points of intersection of warp yarn and weft yarn that are bonded by polymer. The polymer represents a mass of less than or equal to 10%. The preform comprises at least one thermoformed portion in which the warp yarns and the weft yarns are bonded at the intersections thereof by polymer where at least one of the warp and/or weft yarns bears polymer.

Abstract: Said preform (3) defining two parts (21, 23) and comprising: a first group (C1) of layers of warp yarns, which is external in the first part, a second group (C2) of layers of warp yarns immediately beneath said first group, and a first group (T1) of layers of weft yarns which is external in the first part. Furthermore, the first group of layers of warp yarns is absent in the second part and the first group of layers of weft yarns (19) extends into the second part, the first group of layers of weft yarns being external in the second part. The yarns of the first weft group have a lower yarn count than the yarns of the second weft group; and/or the yarns of the first warp group have a lower yarn count than the yarns of the second warp group.