| This work is part of the MFERD (Magnesium Front End Research and Development) project which goal is to develop enabling technologies for the use of magnesium alloys as a principal structural material for cars (mainly made in steel which is four time heavier than magnesium) in order to reduce their mass for both, environmental and security concerns. In this work we have focused on the acoustic part, in the case of a magnesium alloy dash panel. The dash board, by separating the engine compartment from the interior cabin, plays a critical role in the insulation of the car interior. Since the acoustic comfort inside the car has become a marketing argument of great importance, the passage from steel to magnesium dash panel should not deteriorate acoustic performances. In this work, we first conducted a literature review on the types of acoustic treatments used in the automotive industry as well as various techniques of their modeling. We then compared the acoustic performances of a Mg dash with attached traditional acoustic treatments (single-layer, two layers and three layers) to those of a steel and aluminum dash panels with the same mass density, stiffness and/or frequency of resonances. Finally, we optimized different concepts of innovative sound packages applied on the Mg dash panel to achieve a noise performance similar or superior to those of a conventional steel dash. The optimization was done using a SEA (Statitical Energy Analysis) model, coupled with an optimization code based on a genetic algorithm.;Key words: Sound packages, Magnesium alloy automotive dash panel, Statistical Energy Analysis (SEA), Optimization, Genetic algorithm. |
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