A fibrous preform obtained by three-dimensional weaving, comprising a first skin, a second skin, and a central portion connecting them and forming a stiffening element. In a transverse plane, transverse threads of the first skin and the second skin are woven in pairs in the first skin and the second skin on either side of the central portion; the threads of a first pair of the first skin and of a second pair of the second skin are separated into two unitary threads at the central portion by being woven with longitudinal threads, and a thread of the first pair crosses a thread of the second pair at least twice in the central portion.

A fibrous preform obtained by three-dimensional weaving, comprising a first skin, a second skin, and a central portion connecting them and forming a stiffening element. In a transverse plane, transverse threads of the first skin and the second skin are woven in pairs in the first skin and the second skin on either side of the central portion; the threads of a first pair of the first skin and of a second pair of the second skin are separated into two unitary threads at the central portion by being woven with longitudinal threads, and a thread of the first pair crosses a thread of the second pair at least twice in the central portion.

An item may be formed from structures that include holes. Stitching may be used to form a seam that joins the structures. The stitching may be formed from a chain stitch that passes through the holes. The holes may be formed from loops of knit fabric or other holes. Leather layers, polymer layers, fabric layers, and other structures with holes may be joined using the stitching. During fabrication, a layer of material with holes may be placed on an adjustable-shape fixture having a bed of needles. The shape of the bed of nails in the adjustable-shape fixture may then be changed. After the fixture has been used to transform the shape of one or more of the structures, the structures may be placed on needles in an assembly fixture and the stitching between the structures may be formed. The item may be an electronic device cover or other item.

An item may be formed from structures that include holes. Stitching may be used to form a seam that joins the structures. The stitching may be formed from a chain stitch that passes through the holes. The holes may be formed from loops of knit fabric or other holes. Leather layers, polymer layers, fabric layers, and other structures with holes may be joined using the stitching. During fabrication, a layer of material with holes may be placed on an adjustable-shape fixture having a bed of needles. The shape of the bed of nails in the adjustable-shape fixture may then be changed. After the fixture has been used to transform the shape of one or more of the structures, the structures may be placed on needles in an assembly fixture and the stitching between the structures may be formed. The item may be an electronic device cover or other item.

An automatic circumferential insertion apparatus and method for a complex rotary preform. The apparatus includes a double-hinge yarn carrier and a U-shaped bracket. Two ends of the double-hinge yarn carrier are respectively provided with a cylindrical hinge structure. One cylindrical hinge structure is in revolving pair connection with an outer clamping buckle at one end of the U-shaped bracket, and the other cylindrical hinge structure is in revolving pair connection with an inner clamping buckle at the other end of the U-shaped bracket. Two sides of the U-shaped bracket are provided with an electromagnet, respectively. The outer clamping buckle is provided with a pin, which is controlled by triggering, and is triggered simultaneously with the electromagnet at the side where the outer clamping buckle is arranged.

A fiber-composite part having one or more electronic components that are located in arbitrary regions of the internal volume of the part are fabricated using a preform charge. The preform charge has a structure that corresponds to that of the mold cavity in which the part is being formed. By incorporating the electronic components in the preform charge, such components are then precisely located, spatially oriented, and constrained, and such location and orientation is maintained during molding to produce a part with the electronic components in the desired locations and orientations within its internal volume.

Composite liners (such as acoustic panels, fan track liners, and/or ice impact panels or boxes for turbofan engines) and techniques for forming composite liners. In some examples, the composite liner includes at least one region comprising a reinforcement architecture comprising a matrix material, a plurality of relatively tough polymer-based reinforcement elements, and a plurality of second reinforcement elements. The plurality of relatively tough polymer-based reinforcement elements and the plurality of second reinforcement elements are embedded in the matrix material.

The invention relates to a blade of a fan of a turbomachine, comprising a structure made from composite material, including a fibrous reinforcement obtained by means of the three-dimensional weaving of strands and a matrix in which the fibrous reinforcement is embedded,—the fibrous reinforcement comprising a first portion forming the leading edge and a second portion forming all or part of the trailing edge,—the strands of the fibrous reinforcement comprising first strands having a predetermined elongation at break and second strands having an elongation at break higher than that of the first strands, the first portion comprising all or some of the first strands while the second portion comprises all or some of the second strands.

A method for producing a composite material. The method includes the steps of producing an initial dry preform, formed from unidirectional continuous dry fibers, applying non-woven filaments to a first main face of the dry preform, and needling the filaments with a needling device. The needling device includes a plurality of needles, each provided with at least one notch, so that filaments are driven by the needles and arranged in a direction substantially perpendicular to the continuous fibers of the dry perform. The method includes the further step of impregnating the dry preform with an impregnation polymer, the impregnation polymer constituting the matrix of the composite material part.