Abstract: A soundproof panel has a sandwich structure, which includes two outer walls, a core, and modifying elements that are maintained in a fractal distribution by the core. The panel has an improved trade-off between sound attenuation efficiency and the weight of the panel.

Abstract: Damping skin for protecting composite parts includes a composite material having at least two superposed layers, namely a first layer formed from the juxtaposition of hollow spheres, which is intended to be applied and fixed, either directly or indirectly, to the surface of the part to be protected and a second layer covering the first and formed from a wall made of a material having plastic deformation properties.

Abstract: A soundproofing panel having a core sandwiched between a solid wall and a porous wall. The core being connected to the walls and having partitions extending in the thickness direction between the two walls so as to form cells. Each cell containing at least one sound energy dissipating layer constituted by hollow spherical beads having mutually contacting walls that are porous and micro-perforated, and being held in position in the thickness direction between the two walls by nets that are secured to the partitions.

Abstract: A damping structure includes a member defining an internal cavity; an aggregate which includes at least solid bodies in contact and which completely fills the internal cavity; a rigid plate for closing off the internal cavity; and an elastic element which exerts elastic pressure on the rigid plate so as to constrain the aggregate. The member defining the cavity may be elongate with the internal cavity being formed longitudinally inside the member. At least some of said solid bodies may be hollow or solid, compact, made of different materials, of different shapes, and/or of different sizes.

Abstract: A damping structure includes a member defining an internal cavity; an aggregate which includes at least solid bodies in contact and which completely fills the internal cavity; a rigid plate for closing off the internal cavity; and an elastic element which exerts elastic pressure on the rigid plate so as to constrain the aggregate. The member defining the cavity may be elongate with the internal cavity being formed longitudinally inside the member. At least some of said solid bodies may be hollow or solid, compact, made of different materials, of different shapes, and/or of different sizes.

Abstract: A damping structure includes a member defining an internal cavity; an aggregate which includes at least solid bodies in contact and which completely fills the internal cavity; a rigid plate for closing off the internal cavity; and an elastic element which exerts elastic pressure on the rigid plate so as to constrain the aggregate. The member defining the cavity may be elongate with the internal cavity being formed longitudinally inside the member. At least some of said solid bodies may be hollow or solid, compact, made of different materials, of different shapes, and/or of different sizes.

Abstract: A method of fabricating hollow spheres that involve cores in a mixer are covered by a polymeric binder; a first powder material is prepared in the form of an organic powder or a metal or mineral powder or fibers, and a second powder material that is can be decomposed by heat and/or that is soluble in a solvent; said powder materials are mixed together and added into the mixer; the resulting coated cores are dried; the coated cores are baking to destroy the cores and the second powder material, and to cross-link the binder so as to obtain hollow spheres with walls that are porous and perforated; optionally the spheres are immersed in a solvent; and said hollow spheres are subjected to mechanical piercing. Hollow spheres, and a sound-absorber device making use of them.

Abstract: A soundproofing panel (2) comprises a core (4) sandwiched between a solid wall (6) and a porous wall (8), the core being connected to the walls and comprising partitions (12) extending in the thickness direction between the two walls so as to form cells (10) each cell containing at least one sound energy dissipating layer (14), the dissipating layers (14) being constituted by hollow spherical beads (20) having mutually contacting walls that are porous and micro-perforated, and being held in position in the thickness direction between the two walls (6, 8) by nets (22) that are secured to the partitions.

Abstract: The invention concerns a sound-proofing panel, in particular a rotorcraft structural or lining panel: the sound-proofing panel (1) comprises at least two opposite plates (2, 3, 5, 6) forming between them a closed internal space (4), and an aggregate (7) including at least solid elements (8) in contact and which fills entirely said internal space (4).

Abstract: A soundproofing panel comprises a honeycomb core sandwiched between a solid skin and a porous skin, the cells of the honeycomb being divided in the direction of its thickness into at least two resonant cavities by a least one partition which is traversed by passages interlinking the cavities. The partitions are formed by a plurality of hollow microbeads having porous walls, the microbeads being bonded to one another and to the walls of the honeycomb at their points of contact. Such a soundproofing panel combines high performance in terms of linearity as a function of the level of sound excitation, attenuation band, bulk and mechanical strength.

Abstract: The method includes mixing (100) degradable consumable cores (11) with a liquid coating composition (20) including an aqueous solvent (21), a hydrosoluble resin (22) and an anti-agglomerant additive (23), drying (200) the coated cores so as to obtain free balls (12) with a substrate film (2), mixing (300) these balls (12) first of all with a liquid covering substance (30) including a synthetic base product (31) and optionally an auxiliary product (32), then with an anti-agglutinant adjuvant (33), drying (400) the covered balls so as to obtain free ball structures (13) with a covering layer (3), and stoving (500) these ball structures so as to harden their covering layer and degrade the cores and thereby obtain hollow spherules (10). Application in the manufacture of intermediate products for producing in particular energy absorbers.

Abstract: A method for manufacturing continuous, closed and hollow bodies which comprises (a) using cores (25) which are soluble in a solvent, (b) depositing on each core a coating (3) with a suitable mechanical strength to be self-supporting and having open pores to pass a solvent, and (c) placing the cores so coated into a solvent for dissolving the cores; the method of the invention may be implemented in bulk parts, in an economical manner, and allows making hollow bodies, in particular hollow balls, each comprising a continuous skin devoid of any macroscopic perforation and of a kind and with a thickness which are easily adjusted in relation to the desired properties.