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The development of new design tools to predict the vibro-acoustic behavior within the vehicle development process is of essential importance to achieve better products in an ever shorter timeframe. In this paper, an energy flow post-processing tool for structural dynamic analysis is presented. The method is based on the conversion of conventional finite element (FE) results into energy quantities corresponding with each of the vehicle subcomponents. Based on the global dynamic system behavior and local subcomponent descriptions, one can efficiently evaluate the energy distribution and analyze the vibro-acoustic behavior in complex structures. By using energy as a response variable, instead of conventional design variables as pressure or velocity, one can obtain important information regarding the understanding of the vibro-acoustic behavior of the system.

The investigation of critical noise sources on pass-by noise tests is demanding development of the current techniques in order to locate and quantify these sources. One recent approach is to use beamforming techniques to this purpose. The phased array information can be processed using several methods, for example, conventional delay-and-sum algorithms, deconvolution based algorithms, such as DAMAS, and more recently, the generalized inverse beamforming. This later method, presents the advantage of separating coherent sources with better dynamic range than conventional beamforming. Also, recent developments, such as Iteratively Re-Weigthing Least Squares, increases the localization accuracy allowing it to be used in a challenging problem as a fast moving source detection, a non-stationary condition. The work will raise the main advantages and disadvantages on this method using a practical case, a passenger vehicle pass-by test.

With the introduction of hybrid vehicles and the associated elimination of engine and exhaust masking noises, sounds from other sources is becoming more noticeable. Fuel tank sloshing is one of these sources. Fuel sloshing occurs when a vehicle is accelerated in any direction and can create noise that may be perceived as a quality issue by the customer. To reduce slosh noise, a fuel tank has to be carefully designed. Reduction in slosh noise using test- based methods can be very costly and timely. This paper shows how, using the combination of CFD (Computational Fluid Dynamic), FE (Finite Element) and Acoustic simulation methods, the radiated fuel tank slosh noise performance can be evaluated using CAE methods. Although the de-coupled fluid /structure interaction (FSI) method was used for the examples in this paper, the acoustic simulation method is not limited to the decoupled FSI method.

Acoustic performance of vehicle engines is a real challenge for powertrain design engineers. Quiet engines are required to reduce noise pollution and satisfy pass-by noise regulations, but also to improve the driving comfort. Simulation techniques such as the Boundary Element Method (BEM) have already been available for some time and allow predicting the vibro-acoustic response of engines. Although the accuracy of these simulation techniques has been proven, a challenge still remains in the required computation time. Given the large amount of speeds for a full engine run-up and the need to cover a large frequency range, computation times are significant, which limits the possibility to perform many design iterations to optimize the system. In 2001, Acoustic Transfer Vectors (ATV) [1] have been presented to adequately deal with multiple rpm. The ATV provide the acoustic response for unit surface velocities and are therefore independent from the engine's actual surface vibrations.

Prediction of the drive-by noise level in the early design stage of an automotive vehicle is feasible if the source signatures and source-receiver transfer functions may be determined from simulations based on the available CAD/CAE models. This paper reports on the performance of a drive-by noise synthesis procedure in which the transfer functions are numerically evaluated by employing the Fast Multipole Boundary Element Method (FMBEM). The proposed synthesis procedure first computes the steady-state receiver contributions of the sources as appearing from a number of vehicle positions along the drive path. In a second step, these contributions are then combined into a single transient signal from a moving vehicle for each source-receiver pair by means of a travel time correction.