Design of materials for noise reduction in aircraft engines

Finite elements computation for the elastic properties of a regular stacking of hollow spheres

“…For 3 mm diameter hollow spheres (R = 1.5 mm) we have investigated the range of meniscus radii between r = 100 and 300 m and the range of wall thicknesses between t = 20 and 100 m. These values were chosen according to the observations on experimentally realised materials [1].…”

“…The new requirements has triggered the development of new materials presenting both acoustic absorption properties and sufficient mechanical properties (stiffness and strength) [1]. Our investigations has led us to develop a special metallic cellular material obtained with nickel hollow spheres packed in a regular network in order to ensure the constraint of a good reproducibility [2].…”

“…A recent work by Sanders and Gibson [5] has investigated the elastic properties of a network of sintered hollow spheres in the case where the welding neck radius is larger than 0.2 times the sphere radius. We have developed by brazing a set of hollow spheres, a material in which the size of the necks is much smaller [1]. It is therefore of interest to explore this range of dimensions, and to test the validity of the previous calculations outside of the explored range.…”

Entangled Cross-Linked Fibres for an Application as Core Material for Sandwich Structures - Part I: Experimental Investigation

“…as well as from artificial ones (steel wool, glass wool, etc.). Bonded metal entangled cross-linked fibres offer advantages [17][18][19][20][21][22][23][24][25][26][27][28] for use like heat exchanger [26], insulation [27] or noise reduction [28]. They present a relatively low density, a high porosity and a simple production process thanks to cost-effective routes, with considerable versatility concerning metal composition and network architecture.…”

Materials Design for Acoustic Liners: an Example of Tailored Multifunctional Materials

“…[9] As in any systemic problem, several strategies can be envisaged, and it is not clear that materials selection is the key issue. A first guess might be to improve the aerodynamics of the combustion chamber, the compressor, and the turbine to reduce noise generation.…”