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. The method is based on TPA (= Transfer Path Analysis) via matrix inversion and involves the measurement of the vehicle transfer functions. It can be applied to analyse the interior noise under different driving conditions such as driving on smooth or rough roads. TPA is used to estimate the wheel forces and radiated airborne noise, as well as the interior noise level. In this study, good agreement was found between TPA-calculations and measurements of wheel forces (Kistler Wheel Force Sensor) and interior noise.
Finally, advantages and disadvantages of the wheel TPA method are discussed, and future research topics are identified.
