Brüel & Kjær Sound & Vibration Measurement A/S

Good looks Are not enough


With its stringent exterior and interior noise testing programs, the FIAT Group gains competitive advantages in a market where customer satisfaction is the key to success. For its wind tunnel test programs, Brüel & Kjær is FIAT's preferred supplier covering the whole measurement chain – from microphones and accelerometers to the most advanced noisemapping solutions.

The FIAT Group name is synonymous with innovation and creative design of both vehicles for the mass market and sports cars for the privileged few.

In 1899, FIAT was founded by a group of investors, among them, Mr. Giovanni Agnelli who led the company until his death in 1945. Mr. Agnelli was not only recognised for his visionary attitude to vehicles, but also for his industrial professionalism. In 1921, he announced plans to build the famous Lingotto car factory which, at the time, was the largest assembling plant in Europe.

The FIAT Group is today the global manufacturer of the vehicle brands Fiat, Alfa Romeo and Lancia as well as some of the world’s most prestigious brands, Maserati and Ferrari.

The vehicles’ capability to perform in a sporty and safe way is, of course, extremely important, but to satisfy the regulative requirements as well as the consumer’s expectations for noise level comfort is something that also requires top motivated people and advanced noise measurement and analysis tools.

Aeroacoustic Wind Tunnel

'At Fiat’s Aerodynamics Department we are responsible for the test programs for exterior as well as interior noise measurements,' explains Marco Stellato, Full Scale Wind Tunnel Responsible. 'At the concept stage we have to define all the components and we start with virtual simulation, then on to the next level of style models, and finally to test programs in the real vehicle to verify or to optimise the aeroacoustic performance before production.'

'This, of course, includes many different tasks, but our main objectives in the wind tunnel programs are contributions to target setting, benchmarking and verification of components, comparison of alternative components, troubleshooting and competitor analysis.'

'An important part of our decision to choose Brüel & Kjær as preferred supplier for the wind tunnel test programs was the fact that they could provide everything we needed for our measurements –from microphones and accelerometers to the most advanced noise mapping solutions,' says Marco.

FIAT Group Automobile Aerodynamic and Climatic Wind Tunnels

The wind tunnels at FIAT were designed to permit testing of full scale vehicles, commercial vehicles and racing cars, all products of the FIAT Group. On request, FIAT also opens its facilities for third parties. 'The acoustic characteristics of the facility make it possible to carry out the most advanced aeroacoustic analyses and are, of course, an important contributor to the success of the innovative design programs of the FIAT group,' says Marco. The test programs are usually up to 8 hours long. However, in more advanced cases, they might take weeks. 'During the years we have developed efficient processes for our Noise Source Identification programs and this, in conjunction with our PULSE-based solutions from Brül & Kjæ, enhances both our efficiency and our test programs’ accuracy.'

Noise Mapping

For exterior noise mapping, FIAT uses a 60 channel, PULSE-based beamforming solution plus an extra five channels for reference microphones. Another 11-channel PULSE system is used for additional measurements. 'When making 1/3-octave analysis, this configuration allows us to go from 500 Hz to 10 kHz which is perfect for our use,' says Marco. 'For standard noise mapping at about 6.3 kHz we have very fine measurements at the 15 dB range. For the noise map references, we usually use a 10 dB dynamic range, which gives us very good and satisfying results.'

With this configuration, FIAT has improved the measurement time from approximately 40 minutes to around five minutes – an increase in the efficiency level that FIAT is very happy with. Marco states, 'With Brüel & Kjær we are always ensured strong service and support, which is essential for consistency in our test programs. And for interior noise mapping, Brül & Kjæ can supply very advanced test solutions such as Spherical eamforming and Conformal Mapping'.

By assessing Spherical Beamforming and Conformal Mapping, FIAT has tested how easier and faster test results can be achieved for some of their test configurations. 'And for a company like FIAT, who constantly strive to improve processes and find new advanced developments, we can only welcome technologies that constantly push the boundaries of design and sporty performances,' concludes Marco.

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