Noise control at machines
In order to reduce the sound emission of a gearing, the tooth geometry and the casing were optimised. Sheets of the casing critical for the radiation of sound were identified, and the casing was so stiffened as to avoid the sheets to vibrate in resonance.
The sound emission could be reduced by more than 9 dB(A), and disturbing tonal components could be successfully eliminated.
Cascade gear box of a bucket-wheel
In the course of an acoustical weak point analysis, the sound emission behaviour of a straddle carrier was being investigated.
IBS suggested modifications in the machine structure in order to reduce the sound emission. In collaboration with the manufacturer, sound control measures were being developed (acoustical optimisation of the machine casing, enclosure around the motor).
For the new underground railway cars of type DT5 (two-car trainset #5) of the Hamburg Aerial Railway Company, the air conditioning devices are being supplied by Liebherr Transportation Systems GmbH & Co. KG, Korneuburg.
The sound-optimised air conditioning devices were developed by Liebherr in close collaboration with IBS.
Air conditioning device for underground
Using sound intensity mapping, sound sources can be located, and sources that contribute to the radiation of sound in a relevant way can be identified and visualised graphically.
Acoustical weak points of a machine can be identified early in the design process. With the aid of modal analysis, we can calculate the eigenfrequencies of the structure to avoid critical resonances. The effect of stiffening measures to raise or lower the eigenfrequencies can be calculated. In the design process it is possible to avoid that eigenfrequencies meet with exciting frequencies and cause resonance.
Modal analysis of a structure