Smart sound insulation to make cars greener

A EUREKA project is helping car manufacturers to make cars greener through smart sound insulation. In the framework of the ?4 million E! 2411 ERTAC venture, industrial partners from France,
Belgium and Italy have developed a simulation technique that predicts materials’ behaviour for lighter insulation.

‘The manufacturers drastically reduced the time schedules for new car models, so instead of using a slow, time-consuming experimental approach to car acoustics, we switched to developing
simulation techniques using proven models to predict the behaviour of materials for sound insulation,’ says Maurice Fortez, director of the main project partner, French automotive supplier
Treves.

He is sure that the new simulation technique will further speed up the design process and considerably benefit manufacturers: ‘The simulation of the acoustic performances of car components in
the early stages is critical for reducing prototyping costs and improving noise levels inside and outside the car.’

The conventional way of bringing car noise down to an environmentally acceptable level is to stack layer upon layer of heavy materials such as asphalt on the floor of the car to absorb the
sound. This, of course, adds to the overall weight of the car and hence to the fuel consumption. As they are more flexible than most other car components, sound insulation components are an
obvious choice when trying to bring down a vehicles weight and thus its environmental impact. In this way, smart sound insulation could effectively help to reduce the average CO2 emission of
new cars – one of the goals of a recent legislative proposal from the European Commission.

While at the outset the target was a weight reduction of the insulation of 30% to 50%, the project soon found that layering compressed felt with a low density kind already achieved a 50%
reduction. Using foam textile waste to manufacture parts that require some elasticity cut down the weight by another 25%. ‘Through this approach, we even managed to design thinner treatments
for sound insulation in the early stages of the process with the expected mass reduction,’ Mr Fortez explains.

When virtually applying the results to a Renault prototype, the total car weight was reduced by nearly 6.7%. In the case of a Citroen C4, the new technology only weighs 3.4 kg, whereas the
conventional insulation weighed in at up to 11.3 kg.

The new smart sound insulation is soon to be tested in real life, says Mr Fortez: ‘Peugeot wants to use the prototype for its new 207 model. The company is very interested in a big reduction of
car weight and wants to verify the results.’

‘EUREKA really facilitated the partnership that we needed,’ he adds. ‘It helped bring in and find funding for the acoustic simulation specialists and acoustic experts that we needed.’

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