Non-periodic acoustic insulators for low frequencies

To soundproof a plane or a truck, we use materials that must have five characteristics:

• low weight,
• low volume
• low cost,
• low manufacturing uncertainties and
• ability to absorb low frequencies.

To achieve this, we use a set of materials with a periodic structure that can block most frequencies. The problem is that they become less and less effective at low frequencies, below 300 Hz, which are the most damaging.

Christophe Droz, a member of theI4S (Inference for Structures) team at the Inria Centre at the University of Rennes, is exploring the possibility of moving away from the concept of periodic materials via meta-materials designed to interact at a distance and better absorb these vibrations. Such phenomena are observed at the quantum and magnetic levels, and the challenge is to reproduce them at the macroscopic level.

To achieve this, simulators are used to test thousands of hypotheses and configurations, leading to prototypes derived from theory.

"We don't know how far we'll be able to go. But the important thing is to develop original, usable vibro-acoustic phenomena, based on these new concepts. If this works, we'll have a corpus of methods, results and metrics to take things further. We can then try to scale up, and move on to experimentation with industrial partners."

For the full article: A new concept in acoustic insulation for transport

Illustration: © Inria / Christophe Droz - I4S team

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