Method for making a sound reducing panel with resistive layer having structural property and resulting panel

Process for the production of an acoustical attenuating panel comprising a cellular structure (2) covered on one side with a reflector (3) and on the other side with an acoustically resistive layer (1, 1′, 1″) with two components receptively with an acoustical property and with a structural property, characterized in that it consists:

• in emplacing on a mold (M) of a shape appropriate to the panel to be obtained, a layer (1a, 1′a, 13, 15) with structural properties, constituted by filaments pre-impregnated with a thermoplastic or thermosetting resin, by draping, winding or wrapping, such that said layer has a quantity of open surface of the order of 30% of the total surface of the exposed layer,
• in emplacing from above the layer with structural properties, a layer (1b, 1′b, 1″b) with acoustical properties, constituted by a microporous cloth of a thickness of the order of a tenth of that of the layer with structural properties,
• then emplacing the cellular structure (2) and the reflector (3) with if desired the addition of an adhesive (5, 6, 10) between the components,
• at least one step of baking in an autoclave being carried out at the end of at least one of the above steps of emplacement.