Measurement of Rotational Degrees of Freedom in Vibroacoustic Transfer Functions
* Presenting author
Advanced auralisation of vehicle interior noise or quality control in building acoustics requires the determination of vibroacoustic transfer functions. For this purpose, direct or reciprocal measurement setups usually contain impact hammers, shakers or volume velocity sources on the excitation site and triaxial accelerometers or microphone placement in the interior on the receiver site. Problematically, these measurements are restricted to three translational degrees of freedom, whereas the motion of a rigid body would be fully described with six degrees of freedom. Thus, the influence of rotations on a resulting sound field cannot be considered. Studies in structural dynamics indicate that rotational degrees of freedom in frequency response functions are not negligible. In order to deal with uncertainties due to the neglected rotational degrees of freedom in vibroacoustic measurement setups, a reciprocal measuring concept using a MEMS gyroscope was developed and validated by means of FEM simulations. Subsequently, this method was used to determine the relevance of rotational degrees of freedom to the airborne sound radiation in vibroacoustic transfer functions of an electric vehicle drivetrain.