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In the automotive industry, the use of beading is widely spread. Beads are primarily used to stiffen the floor and dash panels. The aim is to reduce vibration levels and hopefully at the same time reduce radiated noise. Beading has a positive effect close to the first panel mode's natural frequency however it can have a negative effect at all other frequencies. Typically, engineers assume a radiation efficiency of “1” (one) over the whole frequency range for simplicity or lack of available implemented formulation in their simulation tools. This assumption directs the investigation at reducing the vibration levels only. This approach can be misleading because even though radiation efficiency tends to “1” (one) above coincident frequency it is not the case below coincidence. While increasing stiffness reduces vibration levels, it also increases radiation efficiency. This can yield to higher levels of radiated noise.

There are many software tools in use today that are implementing the Biot, or complementary, method for the evaluation of foam and fiber materials. The justification of this process is to understand which mechanisms of the noise control material are contributing to the noise reduction and to optimize the material based on its acoustic properties. The disadvantage of this method is that it is quite complex and time consuming to test a material in order to extract the underlying properties that govern the acoustic performance. An alternative inverse method for material characterization based on simple impedance tube measurements has been developed lately. This paper recalls the physics and mathematics behind the method and concentrates on its validation.

Automobile sound package design requires that a Statistical Energy Analysis (SEA) model be built during initial stages of any vehicle program. This allows design changes, noise path analysis and optimization of the sound package to be performed before any program design freeze. The 3D model building process becomes a critical element since it involves many weeks of work before the model is ready for sound package definition and analysis. This paper introduces new developments in building 3D SEA models using templates. A new set of tools has been developed to further automate the SEA model building process. These tools should enable the user to develop a full vehicle SEA model within a few days. The productivity improvement gained by reducing model building time will allow for a more effective use of SEA models in the vehicle development cycle.