In an aircraft, the vibration and human sensitive frequency excitation come from the exterior (engines, aerodynamic flow turbulence on airplane skin, propellers for turbo-proprelled aircraft) and the interior (air-cooling). Classical solutions are used (glass wool, tuned mass system) but they have inherent drawbacks.
ARTEC has developed a low profile shape of its proprietary SPADD® technology, presenting vibro-acoustic performances which are much better than classical solutions. However, the SPADD® 'surface' needs to become suitable for aerospace use and more research is necessary.
The objective of the ATPI project was to propose complementary and/or alternative solutions to the existing acoustic treatments against external sources to reduce the level of operating vibration and to improve the noise reduction on a large frequency band.
These solutions are based on the ARTEC surface technology. By nature, the various materials used in this technology in a performing role cannot be removed and replaced easily. Some interactions with the geometry must be anticipated and will be addressed. The new design was verified with the help of prototype testing to:
- Find replacement materials suitable for this technology; investigate the re-design of the technology itself, in order to comply with the new material; maintain the expected damping performances. The use of visco-elastic polymer and cork materials is already envisaged, the latter having good thermal insulation properties. A low profile requirement is kept as mandatory.
- Develop specific damping technology, complementary to the existing blanket, which is able to provide a high thermo-phonic insulation.
The very final objective of ATPI was to increase the comfort of aircraft passengers by drastically reducing the noise coming from the exterior.
The technical work was split as follows:
- Setting up a technical requirement specification in order to clearly identify the technology characteristics needed. This will be done with the help of Airbus as an end user.
- Study of vibration attenuation and acoustic insulation by adapting the SPADD® Surface technology. This must be done while maintaining the optimum combination of acoustic and vibration treatment to reach the attenuation required in the specification previously established.
- Specific study of the necessary materials (visco-elastic polymer, cork) in order to define the thermal and damping properties. This is necessary for designing an efficient vibration attenuation layer, which is well suited to aeronautical specifications. Cork properties will also be studied for designing an efficient thermo-phonic layer for the same purpose. Compatibility between the envisaged materials will be addressed as well as their behaviour.
- Fabrication of samples of the new device.
- Validation of properties and performance of the samples for aeronautical use. This will be done using standard aeronautical testing methods.
In addition, some standard tasks like the dissemination of results were carried out.
The main result of the ATPI project was the finding of a new product, more efficient than those already known, and used for thermo-vibro-acoustic protection inside aircraft providing:
- Increased dampening performances for vibrations and noise (better comfort).
- Smaller weight than conventional devices at similar performances (weight reduction).
- High spin off possibilities for aeronautics, with large temperature range.
In front of the good results from ATPI, a second project AEROCONF was setup for a continuation effort from ARTEC (internal funding), leading to a final and operational 'surfacic' product for aeronautics. Today the aeronautics certification is envisaged but missing.