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Low interior noise levels in combination with a comfortable sound is an important task for passenger cars. Due to the reduction of many noise sources over the last decades, nowadays tire-road noise has become one of the dominant sources for the interior noise. Especially for manufactures of luxury cars, the reduction of tire-road noise is a big challenge and therefore a central part of NVH development. The knowledge of the noise transmission behavior based on the characteristics of the relevant sources is a fundamental of a modern NVH - development process. For tire-road noise the source characteristics can be described by wheel forces and radiated airborne noise. In combination with the related vehicle transfer functions it is possible to describe the noise transmission behavior in detail. A method for estimating wheel forces and radiated airborne noise is presented.

One of the main customer requirements for passenger cars is a pleasant sound based on a low interior noise level. Because of the reduction of many single noise sources, tyre road noise is now becoming increasingly important. In this paper an efficient approach for investigation of tire road noise is presented. First based on coherence analysis the main noise transmission behaviors are identified. Relevant frequency ranges for structure borne noise and airborne noise can be determined. Additionally it’s possible to separate noise transmission coming from front or rear axle. With this preliminary analysis /1/ it’s possible to reduce the effort to the limit. Now for structure borne noise transmission as well as for airborne noise transmission the critical paths are identified via transfer path analysis (TPA). For the estimation of airborne noise paths two different methods are compared. First the relevant airborne noise transfer paths are estimated via matrix inversion method /2/.

This paper investigates the potential of using FEA poro-elastic Biot elements for the modeling carpet-like trim systems in a simplified setup. A comparison between FEA computations and experiments is presented for two layer (mass-spring) trim systems placed on a test-rig consisting in a 510×354×1.6 mm flat steel plate clamped in a stiff frame excited at its base. Results are presented for a given heavy layer with two different poro-elastic materials: one foam and one fibrous material. The investigations included accelerometer measurements on the steel plate, laser-doppler vibrometer scans of the heavy layer surface, sound pressure measurements in free field at a distance of 1 meter above the plate, as well as sound pressure in a closed rectangular concrete-walled cavity (0.5×0.6×0.7 m) put on top of the test-rig. Computations were carried out using a commercial FEA software implementing the Biot theory for poro-elastic media.