Abstract: A method of fabricating a fiber structure by multilayer three-dimensional weaving between a plurality of weft yarns and of warp yarns, the fiber structure having at least first and second portions that are adjacent in the warp direction, the first portion presenting, in a direction perpendicular to the warp and weft directions, a thickness greater than the thickness of the second portion, includes making the first portion using a step of three-dimensionally weaving warp and weft layers in which a fiber fabric is formed in the form of a Mock-Leno weave grid in a core of the first portion together with skins at a surface of the first portion, a weave of the skins being modified locally so as to deflect certain warp yarns from said skins and weave them with the fiber fabric in the form of the Mock-Leno weave grid.

Abstract: A fiber structure includes a plurality of weft layers and a plurality of warp layers interlinked with three-dimensional or multilayer weaving, the fiber structure including at least first and second portions that are adjacent in the warp direction, the first portion presenting thickness in a direction perpendicular to the warp and weft directions that is greater than the thickness of the second portion. The weft layers situated in the core of the first portion of the fiber structure include braids. The weft layers extending on either side of the weft layers including the braids and going as far as the skin of the first portion include yarns or strands, the braids presenting a section greater than the section of the yarns or strands.

Abstract: A method of fabricating a fiber structure by multilayer three-dimensional weaving between a plurality of weft yarns and of warp yarns, the fiber structure having at least first and second portions that are adjacent in the warp direction, the first portion presenting, in a direction perpendicular to the warp and weft directions, a thickness greater than the thickness of the second portion, includes making the first portion using a step of three-dimensionally weaving warp and weft layers in which a fiber fabric is formed in the form of a Mock-Leno weave grid in a core of the first portion together with skins at a surface of the first portion, a weave of the skins being modified locally so as to deflect certain warp yarns from said skins and weave them with the fiber fabric in the form of the Mock-Leno weave grid.

Abstract: A fiber structure includes a plurality of weft layers and of warp layers interlinked by multilayer three-dimensional weaving, the fiber structure having at least first and second portions that are adjacent in the warp direction, the first portion presenting, in a direction perpendicular to the warp and weft directions, a thickness that is greater than the thickness of the second portion, wherein the first portion has at its core at least one fiber fabric obtained by three-dimensional weaving of warp yarns and weft yarns in the form of a Mock Leno weave grid, the at least one fabric being present between two skins present at the surface of the first portion and being linked to the skins by warp yarns belonging to the skins that are locally deflected into the fabric.

Abstract: A fiber structure includes a plurality of weft layers and of warp layers interlinked by multilayer three-dimensional weaving, the fiber structure having at least first and second portions that are adjacent in the warp direction, the first portion presenting, in a direction perpendicular to the warp and weft directions, a thickness that is greater than the thickness of the second portion, wherein the first portion has at its core at least one fiber fabric obtained by three-dimensional weaving of warp yarns and weft yarns in the form of a Mock Leno weave grid, the at least one fabric being present between two skins present at the surface of the first portion and being linked to the skins by warp yarns belonging to the skins that are locally deflected into the fabric.

Abstract: A fiber blank woven as a single piece by three-dimensional weaving to make a closed box-structure platform out of composite material for a turbine engine fan. In each plane of the fiber blank, a set of warp yarns interlinks layers of weft yarns in first, second, and third portions of the fiber blank, while leaving a closed non-interlinked zone separating the first and second portions over a fraction of the dimension of the fiber blank in the warp direction between an upstream non-interlinking limit and a downstream non-interlinking limit, and while leaving at least one open non-interlinked zone separating the second and third portions over a fraction of the dimension of the fiber blank in the warp direction from a non-interlinking limit to a downstream edge of the fiber blank. A method of fabricating a preform for the closed box-structure platform can use such a fiber blank.

Abstract: In a fiber structure woven as a single piece by three-dimensional weaving, first warp yarns interlink layers of weft yarns in a first portion of the fiber structure adjacent to a non-interlinked zone and also weft yarns of a second portion of the fiber structure beyond the non-interlinked zone, and second warp yarns interlink layers of weft yarns of the second portion of the fiber structure adjacent to the non-interlinked zone and also layers of weft yarns of the first portion of the fiber structure beyond the non-interlinked zone, such that the paths of the first and second warp yarns cross in at least one transition zone extending within the fiber structure from the end of the non-interlinked zone, the transition zone extending in the warp direction over a distance greater than the pitch between adjacent warp columns.

Abstract: A fiber preform is formed by a fiber structure woven by three-dimensional weaving with a plurality of layers of warp yarns interlinked by weft yarns of a plurality of layers of weft yarns, the fiber preform having a first portion and a second portion that extend one another in the weft direction and that are at an angle to each other. In the fold zone and in each weft plane of the fiber structure, two weft yarns situated in a region adjacent to an outside face of the fiber structure situated on the inside of the corner present paths that cross, so that less curvature is imposed on these yarns.

Abstract: In a fiber structure woven as a single piece by three-dimensional weaving, first weft yarns interlink layers of warp yarns in a first portion of the fiber structure adjacent to a non-interlinked zone and also warp yarns of a second portion of the fiber structure beyond the non-interlinked zone, and second weft yarns interlink layers of warp yarns of the second portion of the fiber structure adjacent to the non-interlinked zone and also layers of warp yarns of the first portion of the fiber structure beyond the non-interlinked zone, such that the paths of the first and second weft yarns cross in at least one transition zone extending within the fiber structure from the end of the non-interlinked zone, the transition zone extending in the weft direction over a distance greater than the pitch between adjacent warp columns.

Abstract: A fiber blank woven as a single piece by three-dimensional weaving to make a closed box-structure platform out of composite material for a turbine engine fan. In each plane of the fiber blank, a set of warp yarns interlinks layers of weft yarns in first, second, and third portions of the fiber blank, while leaving a closed non-interlinked zone separating the first and second portions over a fraction of the dimension of the fiber blank in the warp direction between an upstream non-interlinking limit and a downstream non-interlinking limit, and while leaving at least one open non-interlinked zone separating the second and third portions over a fraction of the dimension of the fiber blank in the warp direction from a non-interlinking limit to a downstream edge of the fiber blank. A method of fabricating a preform for the closed box-structure platform can use such a fiber blank.

Abstract: A turbine engine blade made of composite material including fiber reinforcement obtained by weaving a first plurality of yarns with a second plurality of yarns, the yarns of the first plurality of yarns being arranged in successive layers and extending in a longitudinal direction of the fiber blank corresponding to a longitudinal direction of the blade, the reinforcement being densified by a matrix. The blade includes one or more internal channels extending in the longitudinal direction of the blade.

Abstract: A fiber blank woven as a single piece by three-dimensional weaving to make a closed box-structure platform out of composite material for a turbine engine fan. In each plane of the fiber blank, a set of warp yarns interlinks layers of weft yarns in first, second, and third portions of the fiber blank, while leaving a closed non-interlinked zone separating the first and second portions over a fraction of the dimension of the fiber blank in the warp direction between an upstream non-interlinking limit and a downstream non-interlinking limit, and while leaving at least one open non-interlinked zone separating the second and third portions over a fraction of the dimension of the fiber blank in the warp direction from a non-interlinking limit to a downstream edge of the fiber blank. A method of fabricating a preform for the closed box-structure platform can use such a fiber blank.

Abstract: A fiber preform for a vane module of an intermediate casing of a turbine engine, the preform being obtained by three-dimensional weaving. The preform includes first longitudinal segment presenting opposite first and second ends and suitable for forming a first vane; a second longitudinal segment presenting first and second opposite ends and suitable for forming a second vane; and a first transverse segment connecting together the first and second longitudinal segments by their first ends, and suitable for forming a first transverse vane portion such as a flange or a platform.

Abstract: A fiber structure includes a blank portion formed as a single part by three-dimensional weaving between a first plurality of yarn layers and a second plurality of yarn layers, the blank portion corresponding to all or part of a fiber reinforcement preform for a part made of composite material. Outside the blank portion, the fiber structure includes one or more two-dimensional fabric layers, each two-dimensional fabric layer grouping together the yarns of a single layer belonging to at least the first plurality of yarn layers and situated outside the blank portion.

Abstract: A fiber structure includes a plurality of weft layers and a plurality of warp layers interlinked with three-dimensional or multilayer weaving, the fiber structure including at least first and second portions that are adjacent in the warp direction, the first portion presenting thickness in a direction perpendicular to the warp and weft directions that is greater than the thickness of the second portion. The weft layers situated in the core of the first portion of the fiber structure include braids. The weft layers extending on either side of the weft layers including the braids and going as far as the skin of the first portion include yarns or strands, the braids presenting a section greater than the section of the yarns or strands.

Abstract: A thermostructural composite material part including carbon or ceramic fiber reinforcement densified by a matrix having at least one thin portion in which: the thickness of the part is less than 2 mm, or indeed less than 1 mm; the fiber reinforcement is made as a single thickness of multilayer fabric made of spread yarns having a weight of not less than 200 tex; the fiber volume ratio lies in the range 25% to 45%; and the ratio between the number of layers of the multilayer fabric and the thickness in millimeters of the part is not less than four.

Abstract: A method of making a fiber preform, and the preform, for fabricating a turbine engine blade out of composite material, the method including: making a single-piece fiber blank by three-dimensional weaving with layers of longitudinal yarns interlinked by yarns of layers of transverse yarns; and shaping the fiber blank to obtain a single-piece fiber preform including a portion forming an airfoil preform and at least one portion forming a platform preform. During weaving, yarns of a first group of longitudinal yarns are extracted from the fiber blank beside one of side faces of the blank to form a portion corresponding to a blade platform preform, and yarns of a second group of longitudinal yarns are inserted into the fiber blank with mutual crossing of the yarns of the first group and the yarns of the second group.

Abstract: In a fiber structure woven as a single piece by three-dimensional weaving, first warp yarns interlink layers of weft yarns in a first portion of the fiber structure adjacent to a non-interlinked zone and also weft yarns of a second portion of the fiber structure beyond the non-interlinked zone, and second warp yarns interlink layers of weft yarns of the second portion of the fiber structure adjacent to the non-interlinked zone and also layers of weft yarns of the first portion of the fiber structure beyond the non-interlinked zone, such that the paths of the first and second warp yarns cross in at least one transition zone extending within the fiber structure from the end of the non-interlinked zone, the transition zone extending in the warp direction over a distance greater than the pitch between adjacent warp columns.

Abstract: A fiber structure reinforcing a composite material part woven as a single piece by multilayer weaving between plural first and second layers of yarns. The fiber structure includes a portion of decreasing thickness that presents: plural yarn withdrawal parts in surface continuity, with yarns interrupted from the first plural layers of yarns underlying the layer of yarns of the first plural layers of yarns situated in the surface of the structure; and plural yarn withdrawal parts in surface discontinuity, with yarns interrupted from the first plural layers of yarns situated at the surface of the structure, each interrupted yarn replaced in the surface of the structure by a yarn of a layer of yarns underlying the first plural layers of yarns. The yarns of the second plural layers of yarns situated in the surface of the fiber structure are continuous over at least the entire portion of decreasing thickness.

Abstract: A turbine engine blade made of composite material including fiber reinforcement densified by a matrix is fabricated by a method including: performing three-dimensional weaving to make a single-piece fiber blank; shaping the fiber blank to obtain a single-piece fiber preform having a first portion forming a preform for a blade root and an airfoil, at least one second portion forming a preform for a blade inner platform or for wipers of a blade outer platform, and at least one third portion forming a preform for reinforcing a blade inner platform or for overhangs of a blade outer platform; and densifying the fiber preform with a matrix to obtain a composite material blade having fiber reinforcement constituted by the preform and densified by the matrix, and forming a single piece with an inner and/or outer platform incorporated therein.