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Single test rig ensures good vibrations
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01/03/2007
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Vehicle-makers use a variety of test rigs to ensure the right acoustic properties on the road, writes Roger Bish
For example, cars roll on drums that measuring 2 to 3m diameter with various road surfacing materials attached in adjacent strips. Such test rigs are expensive and need a lot of space.
A new adaptive car structure test facility, developed at the Fraunhofer Institute for Structural Durability and System Reliability (LBF) in Darmstadt, combines stress and hydraulic testing stations in a single compact model.
“We expanded the hydraulic test rigs by adding a highly dynamic stressinterface, so we can now simulate structural loads in frequency ranges up to 50Hz as well as vibro-acoustic stress in the 50 to 1,000Hz range,” said the LBF’s Michael Matthias.
The researchers begin by using sensors to record vibrations on the tyres and in the car interior that occur when driving on various road surfaces at different speeds and with different tyre profiles. These vibrations are then archived in a database so they can be quickly be fed into the test rig. “We use an algorithm to modify this vibration signal in the same way it would change on its way to the ear during real-worlddriving,” said Matthias.
On the test rig, the wheels are replaced by electric motors that work against the car’s acceleration and simulate the resistance generated by gradients and road friction.
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Author
Roger Bishop
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