Application of Hybrid Frequency Domain Substructuring for Modelling an Automotive Engine Suspension

Abstract

A practical application of hybrid FRF-coupling (Frequency Response Function) in the development of a passenger car is presented. First, a short review is given about FRF-coupling in general. Next, some problems are discussed which may be encountered when both analytical and experimental FRF-data is used in FRF-coupling. This is also known as hybrid modelling. The main part of this paper presents a successful application of hybrid FRF-coupling to analyze and solve an interior noise problem of a passenger car. Both analytical and experimental FRFs were used to create a hybrid dynamic model of a complete passenger car. The engine and its suspension system were modelled using finite elements, while the remainder of the car was modelled by experimentaly derived FRFs. This hybrid model was then used to compute the response of the vehicle due to the engine excitation. Measured noise transfer function were used next to compute the interior sound pressure level using forced response results of the hybrid car model. Subsequently, the hybrid model was used to analyze the problem, and to predict the effects of an alternative design of the engine suspension on interior noise. Numerical results indicated that the alternative design would have a significant positive effect on noise. This was confirmed by verification measurements on a car.