Abstract: An element (26) for sound absorption is intended for being mounted on components of aircrafts, such as engine nacelles. The element includes a face-sheet (28), which is, at least in a region thereof, acoustically permeable, a substantially sound-reflective back-sheet (30) and a honeycomb layer (32), “sandwiched” between the face-sheet (28) and the back-sheet (30) and defining a mesh structure which has hollow cells (34, 34?) laterally neighboring one another. The cells (34, 34?) are adapted to make the sound waves that enter through the face-sheet (28) and are reflected by the back-sheet (30) resonate inside their side walls. The element (26) has a passage (36) that connects together a group of the cells (34, 34?), thereby causing the cells to acoustically cooperate with one another.

Abstract: A method for making hollow stiffening elements with co-curing technique on a structure made of composite material 1 includes the use of at least a lamination and polymerization spindle 2 upon which is positioned at least a rolled section 3. The rolled section 3 forms at least a hollow structure 11 where there is the spindle 2, including the following operational phases: coating the spindle 2 with at least a first anti-adherent layer 41; coating the spindle 2 with at least a second heat-shrinking layer 42; heating the coated spindle 2; positioning the spindle 2 on the surface of the structure 1; laminating the surface 1 through at least a rolled section 3; heating the structure 1 with at least a positioned rolled section 3; extracting the spindle 2 from the hollow structure 11.

Abstract: An element (26) for sound absorption is intended for being mounted on components of aircrafts, such as engine nacelles. The element includes a face-sheet (28), which is, at least in a region thereof, acoustically permeable, a substantially sound-reflective back-sheet (30) and a honeycomb layer (32), “sandwiched” between the face-sheet (28) and the back-sheet (30) and defining a mesh structure which has hollow cells (34, 34?) laterally neighboring one another. The cells (34, 34?) are adapted to make the sound waves that enter through the face-sheet (28) and are reflected by the back-sheet (30) resonate inside their side walls. The element (26) has a passage (36) that connects together a group of the cells (34, 34?), thereby causing the cells to acoustically cooperate with one another.

Abstract: A method for making hollow stiffening elements with co-curing technique on a structure made of composite material 1 includes the use of at least a lamination and polymerization spindle 2 upon which is positioned at least a rolled section 3. The rolled section 3 forms at least a hollow structure 11 where there is the spindle 2, including the following operational phases: coating the spindle 2 with at least a first anti-adherent layer 41; coating the spindle 2 with at least a second heat-shrinking layer 42; heating the coated spindle 2; positioning the spindle 2 on the surface of the structure 1; laminating the surface 1 through at least a rolled section 3; heating the structure 1 with at least a positioned rolled section 3; extracting the spindle 2 from the hollow structure 11.