The Investigation of the Road Vibration in the Car Using the Principal Component Analysis

The powertrain and the road inputs are the major contributors to the noise and vibration of the cars. This paper is focused to find out the road principal components (virtual references) that contribute to the complex noise and vibration problems in order to reduce them. In the first step it defines the road frequency response functions set, that is coming from a test database. These FRFs are later used for calculating the response of the car body, subjected to the measured road loads. It follows the creation of the crosspower set. Crosspowers describe the spectral contents of the part of a response signal that is correlated to a reference signal. In the next step the road principal components are calculated. The PCA breaks down the non-coherent vibrations into coherent sets of vibrations and assigns the latter to so-called virtual sources that can be treated in a similar way to coherent sources. The referenced virtual spectra will be applied to the model and the response is calculated. Two applications are described to demonstrate the usefulness of this concept.