Abstract: A method of fabricating a composite part, includes forming a fiber preform for the part that is to be obtained by depositing a plurality of fiber structures impregnated with a thermoplastic polymer onto a surface, with deposition being performed by automated fiber placement; eliminating the thermoplastic polymer present in the preform by dissolution with a solvent; and injecting a liquid impregnation composition into the pores of the fiber preform after eliminating the thermoplastic polymer in order to form a matrix in the pores of the fiber preform.

Abstract: A device for fastening a downstream end of an air inlet on a fan casing of an aircraft turbojet engine nacelle is provided. The device includes an acoustic shroud, a first flange coupled to the fan casing, a second L-shaped flange having a base coupled to the acoustic shroud, and a collar linked to the first flange. The acoustic shroud extends from an upstream segment to a downstream segment which defines an inner skin and an outer skin that encloses an acoustic panel. The collar further includes a protrusion that extends from the outer skin to the downstream segment.

Abstract: A method for manufacturing a preform has a non-developable end shape having, about a longitudinal axis (A), an end overall radius of curvature (R2), and, in at least a longitudinal section, curved segments forming bending radii linking straight segments. The method includes a step of depositing successive layers giving the preform an initial substantially rotational shape having, about the longitudinal axis (A), an initial overall radius of curvature, then a step of deploying the preform by increasing the initial overall radius of curvature until the end overall radius of curvature is reached (R2), in order to close the bending radii of the curved segments.

Abstract: The disclosure relates to a method of manufacturing a preform including a core and a sole. The method includes contour weaving the preform on a lap roller having a groove or an outgrowth allowing shape weaving of the core and the sole of the preform. At least one portion of the core and at least one portion of the sole include weft yarns which cross each other on common warp yarns.

Abstract: The present disclosure relates to a preform that includes layers of textile reinforcements that are arranged in a mold by an automatic placement head and are connected to each other, and which can be dry or pre-impregnated, in order to form a part made of composite materials after curing of an impregnating resin. The part includes a folding produced by conformation of the preform after the placement of the layers of textile reinforcements. At the folding, there are spacings between at least some of the layers of textile reinforcements.

Abstract: A method for producing an acoustic attenuation panel from a composite material with a ceramic oxide matrix is provided that includes draping a plurality of plies having fibrous reinforcements including fibers of ceramic material in a mold to define a first skin, depositing blocks made of fugitive material on the first skin such that a space between two blocks is defined, and draping a second plurality of plies on a surface formed by the blocks such that a second skin is defined. Rounded corners of the blocks define radii for connecting the first and second skins with walls of a honeycomb core of the acoustic panel. The method further includes using a liquid medium to infiltrate the skins and spaces with a precursor of a ceramic phase, removing the liquid medium by evaporation or polymerization, and sintering to consolidate the ceramic oxide material and removal the fugitive material.

Abstract: A single-piece woven fiber structure for fabricating an axisymmetric part of varying diameter made out of composite material, the fiber structure having a portion of frustoconical shape with a large diameter and a small diameter, the ratio between the large diameter and the small diameter being not less than 2. The fiber structure is formed by winding layers of warp and weft yarns that are woven on a mandrel having a profile that is defined as a function of the profile of the part to be fabricated with warp yarn take-up. For each layer of yarns, the weft yarns are angularly distributed on a single diameter in a zone of the large diameter of the portion of frustoconical shape and on at least two different diameters in a zone of the small diameter of the portion of frustoconical shape in order to form at least two superposed plies of weft yarns.

Abstract: The present disclosure relates to a method for producing an acoustic attenuation panel having two outer skins made from a composite material with a ceramic matrix containing a fibrous reinforcement. The skins are assembled on each side of a central honeycomb core having walls forming acoustic cavities produced by at least partial electrochemical conversion of aluminum into aluminum oxide. The method includes inserting a fugitive filler material into the acoustic cavities, leaving an annular space free in each cavity, on each side against the skin, extending around the cavity, and a step of sintering the composite material, in which the fugitive material is removed and the spaces around the cavities are filled with the composite material.

Abstract: The present disclosure concerns a porous body made of a ceramic-matrix composite material for an acoustic attenuation panel and a method of manufacturing the porous body. The porous body includes a plurality of interwoven ceramic fibers, a metal oxide matrix, and a plurality of channels interwoven with the ceramic fibers and interconnected together. The channels define at least one cavity. In one form, at least one channel is wrapped around a ceramic fiber. In another form, at least one ceramic fiber and at least one channel are twisted together. In yet another form, at least one channel is wrapped around a ceramic fiber and twisted with the ceramic fiber. The present disclosure also concerns an acoustic attenuation panel including the porous body and an aircraft propulsion unit having such a panel.

Abstract: The present disclosure particularly relates to an acoustic attenuation structure for a propulsion assembly of an aircraft. The acoustic attenuation structure includes an acoustically reflective wall and a sandwich panel. The sandwich panel includes a honeycomb structure surrounded by two acoustically porous skins, a rear skin and a skin. The acoustically reflective wall and the sandwich panel are arranged in such a way as to be separated by a layer of air.

Abstract: A flow straightening vane made of composite materials includes a core made up of three-dimensional woven textile rods which core is surrounded by a textile covering, this core and this covering being consolidated using a thermoset resin.

Abstract: The present disclosure provides a method for manufacturing a preform made of reinforcement fibers woven in a longitudinal direction. The preform is impregnated with resin in order to form an elongated element having a variable transverse cross-section. In one form, the method includes the step of simultaneously including a reduction (or increase) in width and an increase (or reduction) in height. The variable cross-section includes, along the length thereof, a consistent number (c) of continuous warp threads arranged in layers. The method for reducing width includes carrying out a change in weave, adding additional weft threads, and simultaneously drawing the teeth of the longitudinal beater reed closer together so as to increase the number of layers.

Abstract: A device for fastening a downstream end of an air inlet on a fan casing of an aircraft turbojet engine nacelle is provided. The device includes an acoustic shroud, a first flange coupled to the fan casing, a second L-shaped flange having a base coupled to the acoustic shroud, and a collar linked to the first flange. The acoustic shroud extends from an upstream segment to a downstream segment which defines an inner skin and an outer skin that encloses an acoustic panel. The collar further includes a protrusion that extends from the outer skin to the downstream segment.

Abstract: The present disclosure concerns a preform for a curved composite stiffener for an axisymmetric part such as a shroud, including at least one web and at least one flange curved about an axis of revolution of the preform and defining a substantially “T” or an “I” shaped section. In one form, the preform includes a web and a flange, wherein the web includes a plurality of warp yarns circumferentially oriented relative to the axis of revolution of the preform, and a plurality of weft yarns oriented radially relative to said axis, and the flange includes a plurality of warp yarns circumferentially oriented relative to the axis of revolution of the preform, and a plurality of weft yarns substantially parallel to said axis.

Abstract: The disclosure relates to a shape-woven preform which has an omega-shaped cross-section including a core and a sole. At least one part of the core and at least one part of the sole have weft yarns in common with one another.

Abstract: The present disclosure related to a method for manufacturing a structure with cellular cores that can be used in a structural panel of a turbojet nacelle, including at least one block of cellular cores. The at least one block of cellular cores includes a central portion with core honeycomb cells, and two side portions each including side honeycomb cells. The side honeycomb cells have edge honeycomb cells situated on edges of a side part of a block, and adjacent honeycomb cells. In particular, the method includes: A) forming junction walls on the side honeycomb cells by opening the edge honeycomb cells, the junction walls being capable of interacting for forming a junction area; B) unfolding the junction walls thus formed in step A; and C) joining the junction walls thus unfolded in step B and belonging to two different side portions end-to-end.

Abstract: A method for manufacturing an air-intake structure for a turbojet-engine nacelle includes two component parts, i.e. one air-intake lip structure and one outer cowl for the air-intake structure. In particular, the method includes the following steps: separately manufacturing the component parts such that each integrates one overlapping portion with a part to which is to be attached. The overlapping portion is configured such that an outer surface of the outer overlapping portion provides continuity with an outer surface of the outer cowl associated with the inner overlapping portion. To secure the overlapping portions, glue or a fastener may be used.

Abstract: A single-piece woven fiber structure for fabricating an axisymmetric part of varying diameter made out of composite material, the fiber structure having a portion of frustoconical shape with a large diameter and a small diameter, the ratio between the large diameter and the small diameter being not less than 2. The fiber structure is formed by winding layers of warp and weft yarns that are woven on a mandrel having a profile that is defined as a function of the profile of the part to be fabricated with warp yarn take-up. For each layer of yarns, the weft yarns are angularly distributed on a single diameter in a zone of the large diameter of the portion of frustoconical shape and on at least two different diameters in a zone of the small diameter of the portion of frustoconical shape in order to form at least two superposed plies of weft yarns.

Abstract: A structural component is made of composite material, including at least one assembly orifice, the component being composed of a stack of plies of fibers which include at least one layer of plies of regular fibers and at least one reinforcing ply. The reinforcing ply is composed of a woven composite textile preform formed by a weave obtained by assembling a plurality of circumferential warp fibers that form a path around the assembly orifice and weft fibers that extend radially with respect to the center of the orifice.

Abstract: The present disclosure related to a method for manufacturing a structure with cellular cores that can be used in a structural panel of a turbojet nacelle, including at least one block of cellular cores. The at least one block of cellular cores includes a central portion with core honeycomb cells, and two side portions each including side honeycomb cells. The side honeycomb cells have edge honeycomb cells situated on edges of a side part of a block, and adjacent honeycomb cells. In particular, the method includes: A) forming junction walls on the side honeycomb cells by opening the edge honeycomb cells, the junction walls being capable of interacting for forming a junction area; B) unfolding the junction walls thus formed in step A; and C) joining the junction walls thus unfolded in step B and belonging to two different side portions end-to-end.