Innovative Acoustic Material Concept Integration into Vehicle Design Process 2020-01-1527

Integration of acoustic material concepts into vehicle design process is an important part of full vehicle design. The ability to assess the acoustic performance of a particular sound package component early in the design process allows designers to test various design concepts before selecting a final solution and long before a design freeze. This paper describes an innovative acoustic material concept which is easily integrated in a design process through the use of vibro-acoustic simulation and a database of intrinsic properties of acoustic materials: The Biot Parameters. Biot parameters are widely used in simulation in many industries (and used the most in the automotive industry) to describe the physical interactions between the acoustic waves travelling through foams, fibers or homogeneous metamaterials and the solid and fluid phase of these poro-elastic materials. Therefore, the surface absorption, the insertion loss and the added damping provided by the acoustic treatments on the base plate can all be predicted accurately. Simulation can be performed at component and full vehicle level using Biot parameters since these are the intrinsic properties of the porous material, the same way Young’s Modulus is an intrinsic property of steel. Furthermore, Biot parameters can be directly used in FEM (Finite Element Method), BEM (Boundary Element Method) and SEA (Statistical Energy Analysis) thanks to the existence of porous finite elements or the use of TMM (Transfer Matrix Method). This paper introduce a new acoustic material concept which provides a combination of absorption, transmission loss and added damping on the panel it is attached to. It has shown unique vibro-acoustics performance when tested on a German car manufacturer flagship vehicle and provides the ability to reduce the space needed for sound package component compared with classical solutions. It is manufactured by impregnating a fraction of total thickness of a PU foam. This results in two acoustic layers, one light foam and the other a heavy and high damping layer. A description of the Biot parameter measurements of each layer and test results for each sample tested along with standard deviation are provided. Finally, a simulation analysis using TMM is performed to assess the airborne and structureborne acoustic performance of this new unique material.