Abstract: The invention relates to a method for manufacturing a structure with cellular cores (202) that can be used in the structural panel of a turbojet nacelle, including at least one block of cellular cores (A, B) having a central portion (5a, 5b) with core honeycomb cells (7a, 7b) and at least two side portions (9a, 9a?, 9b, 9b?) each including side honeycomb cells (11a, 11b), wherein said method includes the following steps: A) forming junction walls on the side honeycomb cells (11a, 11b), the junction walls being capable of interacting for forming a junction area (213); B) unfolding the junction walls thus formed; and C) joining the walls thus unfolded (46) and belonging to two different side portions (9a, 9b) end-to-end so that said junction walls (46) are fitted together so as to form a junction area (213). The invention also relates to a structural panel and to a nacelle including a structure with cellular cores obtained by said method.

Abstract: The invention relates to a method for producing a part comprising a hollow body made from a composite material, using preforms (11, 12), said method including the following steps: a step in which the preforms are disposed around a suitable supporting element (1) such that the coupling edges of each preform (11, 12) overlap, and come into contact, with a coupling edge of another preform (12, 11); a step in which the coupling edges of each preform are joined along a seam; and a step in which the supporting element is removed and a mould core is inserted in its place before the assembly is placed inside a mould and resin is injected using an RTM/LRI method, prior to the polymerisation of said resin.

Abstract: The invention relates to a preform (300) intended to form a hollow structural mechanical part, said preform (300) comprising: a central body (301) forming a median plane (307) and extending substantially along a main axis (309) contained in the median plane (307); and two side parts (303, 305) extending substantially along the median plane (307) along a secondary axis (311) substantially perpendicular to the main axis (309), the central body (301) and each side part (303, 305) including weft fibres interconnected by binder fibres. The weft fibres extend along substantially parallel planar weft layers, and the thickness (E) of each side part (303, 305) decreases along the secondary axis (311) moving away from the central body (301). The invention also relates to a method for producing one such preform, as well as to a hollow structural mechanical part.