The invention relates to a method for producing a folding core (50, 190, 300, 360, 370, 380) for a lightweight structure, wherein in a first method step bending lines (70, 170, 180) are applied onto a deformable flat semi-finished product (40).

A method for manufacturing an acoustic panel by welding of at least two acoustic components made of thermoplastic material, a thermal gradient being applied on the acoustic components during the welding operation so as to apply a temperature higher than the glass transition or melting temperature of the material on the area to be welded and so as to apply a temperature lower than or equal to the geometric stabilization temperature of the material on the parts furthest from the area to be welded.

A curved composite structure, comprises at least two curved composite panel segments joined together. Each of the panel segments includes a fluted core sandwiched between first and second facesheets. A layer of adhesive is used to rigidly bond the panel segments together.