Testing and Simulation of Anti-Flutter Foam and High Damping Foam in a Vehicle Roof Structure

The excitation of structural modes of vehicle roofs due to structure-borne excitations from the road and powertrain can generate boom and noise issues inside the passenger cabin. The use of elastomeric foams between the roof bows and roof panel can provide significant damping to the roof and reduce the vibration. If computer-aided engineering (CAE) can be used to predict the effect of elastomeric foams accurately on vibration and noise, then it would be possible to optimize the properties and placement of foam materials on the roof to attenuate vibration. The properties of the different foam materials were characterized in laboratory tests and then applied to a flat test panel and a vehicle body-in-white. This paper presents the results of an investigation into the testing and CAE analysis of the vibration and radiated sound power of flat steel panels and the roof from the BIW of an SUV with anti-flutter foam and Terophon® high damping foam (HDF) materials. The test program was conducted using a scanning laser vibrometer to measure the surface vibration and a sound intensity probe to measure radiated sound power. The structural and acoustic responses of the panel and roof have been normalized to the input force. In parallel with the flat panel, finite element CAE simulation of the foam materials in the panel tests was performed and the results compared to the test results using different finite element (FE) foam modeling techniques. The results of this work are presented and discussed.