By design, cavity structures in the body shell ensure the required stability and torsional stiffness of the vehicle. A negative effect of those channels is the transport of structure-borne and airborne noise to the vehicle's occupant's ear. The noises perceived as disturbing are reduced by means of numerous measures. The common method of blocking the sound propagation through the shell channels is the application of bulkheads with expanding foam seals. Even more efficient is acoustic foam applied in liquid form. This highly efficient component in the passive acoustic package is sued in many current models. The application of foam directly at the assembly line has successfully been applied for some years all over the world. In doing so, the foam material is, in a high-pressure process, applied in the car body in liquid form. The chemical reaction is completed still within the production cycle time and this results in a light flexible foam with a perfect 3D-geometry and excellent insulating and damping characteristics. The latest development constitutes a viscoelastic foam system particularly optimized for the acoustic requirements. The interior noise comfort is measurably increased although the weight was minimized. The conclusions are: 1. With the new viscoelastic series foam, it is possible to measurably and audibly increase the interior noise comfort. 2. In the area of the bulkhead, it is possible to simulate the results in the test laboratory on substitute structures in top quality. 3. The efficiency of the new series foam is demonstrably high but, in detail, not completely understood in theory. The dynamic foam characteristic values storage and loss modulus alone are not sufficient for the foam characterization.
Optimized interior acoustics by liquid application of a new viscoelastic 2kpolyurethane foam to selected cavities of the painted car body
2013
8 Seiten, Bilder
Aufsatz (Konferenz)
Englisch
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