During a vehicle development, measurements on cut out modules in large coupled reverberant rooms are often carried out in the middle and high frequency range in order to optimize the insulation performance of the trims (Transmission Loss). Using optimal controlled mounting conditions, we have been able to extend the frequency range to the low frequencies in order to validate trim FEM models of a dash and floor insulator modules with structureborne and airborne excitations. Both coupled response with movable concrete cavities (structureborne excitation) and Transmission Loss with the coupled reverberant rooms (airborne excitation) have been measured and simulated for various types of insulators on the same setup, without any change on the mounting conditions. An additional movable absorbing environment in the large reception room has been deployed in order to carry out laser vibrometer (skeleton velocity) and p-u probes (particle velocity and intensity) measurements on the surface of the trims. By incorporating the maximal treatment mock-ups of the cut out modules as additional trims in the models, we have obtained good correlation results between measurements and simulations for both bare and trimmed configurations for a dash and floor insulators with structureborne and airborne excitations.

Virtual SEA is a modeling process using FE computations to build an SEA model including equivalent masses, modal densities, and CLF, but excluding DLF since damping modeling in the mid-high frequency range is still an open issue. This technique, previously proposed by some of the authors, is applied to a production vehicle in the range 200-1000 Hz. The actual vehicle is simultaneously measured at a subset of the FE nodes. The automated sub-structuring provided by Virtual SEA (20 subsystems at 630Hz) is used to favorably position 64 sensors on the body. Next, an experimental SEA procedure is performed: a full transfer matrix is measured between more than 1000 excitation (hammer) locations and the sensors. In order to compensate for structural heterogeneity, input mobilities are measured at every point and used to normalize the transfer matrix As all measurement points are associated to FE nodes, computed input mobilities can be compared to measurements. Finally, the SEA model identification is carried out for both experimental and virtual SEA. As far as damping (DLF) can only be known experimentally, comparisons of the numerical and experimental approach only concern the orher SEA parameters (CLFs, modal densities ...) and transfer functions.