Method for manufacturing a structure with cellular cores for a turbojet nacelle

A method for manufacturing an alveolar core structure for an acoustic attenuation panel, the alveolar core structure including a plurality of adjoining acoustic cells which form the alveolar core, each acoustic cell extending along a main axis (A) corresponding to an axis of propagation of a sound wave, from a front end up to a rear end, and being delimited by a peripheral wall defining a primary duct for circulating the sound wave, at least one cell including a secondary duct for circulating the sound wave, the secondary duct comprising a secondary duct wall, having a first end proximal to the front end of the cell, the first end defining a sound wave inlet, and an opposite second end, the secondary duct comprising a sound wave outlet located near the rear end of the cell, the method comprising:

• a fastening step in which:
• adhesive tapes parallel to each other and transverse to a longitudinal direction of said first plate are applied, on a first longitudinal plate, so as to form nodal areas,
• the secondary duct in the form of a flattened element is fastened, on the first plate between two nodal areas, by gluing at the sound wave inlet, the flattened element having folds intended to delimit edges to obtain one of a polygonal conical and a frustoconical-shaped secondary duct;
• a second plate is applied and fastened by gluing to the nodal areas, and to the flattened element at the sound wave inlet;
• and
• a deployment step in which the first and second plates are moved away from one another so as to form the peripheral wall of the cells and so that the flattened element is deployed to form the secondary duct.

A method for manufacturing an alveolar core structure for an acoustic attenuation panel, the alveolar core structure including a plurality of adjoining acoustic cells which form the alveolar core, each acoustic cell extending along a main axis (A) corresponding to an axis of propagation of a sound wave, from a front end up to a rear end, and being delimited by a peripheral wall defining a primary duct for circulating the sound wave, at least one cell including a secondary duct for circulating the sound wave, the secondary duct comprising a secondary duct wall, having a first end proximal to the front end of the cell, the first end defining a sound wave inlet, and an opposite second end, the secondary duct comprising a sound wave outlet located near the rear end of the cell, the method comprising:

• a fastening step in which:
• adhesive tapes parallel to each other and transverse to a longitudinal direction of said first plate are applied, on a first longitudinal plate, so as to form nodal areas,
• the secondary duct in the form of a flattened element is fastened, on the first plate between two nodal areas, by gluing at the sound wave inlet, the flattened element having folds intended to delimit edges to obtain one of a polygonal conical and a frustoconical-shaped secondary duct;
• a second plate is applied and fastened by gluing to the nodal areas, and to the flattened element at the sound wave inlet;
• and
• a deployment step in which the first and second plates are moved away from one another so as to form the peripheral wall of the cells and so that the flattened element is deployed to form the secondary duct, wherein the secondary duct is glued along an entire perimeter to the walls of the cell delimited by the two nodal areas between the first plate and the second plate.