Dipl.-Ing. Konrad Weisheit
Calculation of interior noise in Automobiles
Interior noise in vehicles constitutes a significant problem in the automotive industry. The customer-Knowingly or not - perceives noise as a lack of quality, in a product for which he has paid a lot of money, most likely. Therefore all manufacturers put a lot of effort into avoiding sources of unwanted noise in a car's interior. In addition to numerous complex and lengthy trials, expensive measures in the manufacturing process intended to remedy noise, burden the result. Due to the high volume of produced cars, the smallest additional expenditure (per vehicle) can lead to considerable costs.
Generally, the later a problem is detected, the less scope there is for its solution and the higher the costs. Therefore, simulation methods are applied to identify weak spots as early as possible. Usually linear calculation methods are used and the results are evaluated in various ways. However, since the relevant mechanisms of noise generation are based on contact and friction, i.e. to nonlinearities, the information provided by such calculation methods is severely limited.
Goal of this project is to develop a method that takes into account the mechanisms of noise production and thus delivers a significantly more reliable noise prediction. In the first step a method is developed, that calculates the underlying nonlinear oscillations as effectively as possible. Subsequently, the sound power emitted by the vibrating system is calculated. It serves as the parameter, on the basis of which the noise is ranked, to determine whether action is needed or not. Results from calculation are compared to those, measured at a specially designed test rig, to quantify the performance of the method as well as related limitations in sound prediction.