ACDC project: advanced composites for acoustic and vibration damping control

The development of aircraft engines, coupled with increasingly stringent requirements in terms of acoustic comfort for passengers and crew, is leading to a review of the materials and technologies currently used to attenuate the transmission of vibrations and noise in the nacelle and cabin areas. The design of these new engines results in a modification of the vibration frequencies and noise generated during their operation. It also considerably reduces the space available in the nacelle for integrating treatment systems.

The ACDC project takes into account all the requirements and technical needs of these future engines in order to evaluate new disruptive concepts for vibration and acoustic transmission reduction systems for the nacelle and cabin.

The project

The aim of the project is to propose technological “building blocks” based on materials, structures and technological concepts for sound attenuation in transmission and absorption at low frequencies. With a budget of €2.3 million, the IRT Saint Exupéry, along with Airbus, Metacoustic, Porcher industries, Bysco, SDTEch, Continental, ICA, ISAE, Onera and LAUM, is participating in the development of new solutions at different scales. The ACDC solutions are intended to be deployed on various elements of the cabin, such as skin panels, floors and seats.

The resources deployed to achieve the project’s objectives range from an experimental platform dedicated to manufacturing processes to digital modelling resources. The ACDC project is divided into several activities to develop:

• materials, structures and technologies for acoustic absorption;
• biobased materials, metastructures and new fastening systems for the attenuation of sound transmission by vibroacoustic phenomena;
• the construction of POCs representative of the solutions studied.

After 24 months of the project, the development of activities is progressing in line with the objectives set. The IRT is developing:

• geometrically optimised materials using its digital modelling tools and 3D printing facilities; TRL4 demonstrators are currently being produced;
• biosourced composites based on natural fibres and thermoplastic matrices with high environmental value and enhanced performance; the implementation and characterisation of different fibre/matrix combinations optimised for energy dissipation is in progress;
• absolute filter-type lattice structures dealing with linear and non-linear phenomena; the physical modelling and structural optimisation tools needed to achieve the desired performance have been put in place. These tools have been successfully validated experimentally by the production of a polymer lattice structure using additive manufacturing and its characterisation on vibrating pots.

ACDC will enable the IRT Saint Exupéry to pursue its varied developments in terms of innovative composite and polymer manufacturing processes for vibro-acoustic applications. The polymer additive manufacturing process is still underdeveloped in terms of uses for high-performance technical applications, and will require further work to understand the relationship between materials and processes.

Biosourced composite materials based on natural fibres have intrinsic properties, but need to be optimised for vibro-acoustic applications in the aeronautical industry. Through its slurry composite impregnation manufacturing processes, and with the partnership of its industrial members, textile specialist such as Porcher Industrie, the IRT is pursuing its activities to develop more eco-responsible materials and processes.

Academic work with ISAE, ICA, LAUM and ONERA, which are specialised in non-linear phenomena and acoustics respectively, will enable to speed up research thanks to complementary skills.

It’s an ambitious project that will enable to screen a wide range of potential solutions for these vibro-acoustic applications, bringing together the entire chain of entities and skills required for a rapid rise to maturity. From academia to industry; from semi-product manufacturers to solution developers; from startups to end-users, the project brings together a representative panel of French entities and technical skills.