The industrial solution used today to improve the acoustic performance of a structure is often ensured by the addition of damping treatments such as elastomer, PVC or bituminous. In the transportation, these materials increase the costs and mass of the vehicle and have a negative environmental impact. Unlike theses heavy materials, it is commonly known in the professional standards of automotive designers that foams in vehicle trim provide damping to the structure. It has been shown that some impregnated PU foam coatings provide significant and equivalent damping to conventional bituminous materials used in the automotive industry. This observation makes it possible to extend the function of the trim to vibration damping, in order to mutualize the both problem (acoustic and vibration) in one treatment. To understand and quantify this dissipation mechanism involved by adding a porous material to a supporting structure [1], it is proposed to treat the problem from the angle of an experimental quantification obtained by an inverse problem. The proposed approach is based on the use of the Force Analysis Technique (FAT) method [2-3], where the first objective is to locate and quantify the forces applied to a vibrating structure. In this case, the FAT is designed to define the damping provided by the foam to the vehicle trim [4-5].

Keywords : foam, damping, FAT method

References: 

[1] Z. Abbadi, N. Merlette, N. Roy, Response Computation of Structures with Viscoelastic Damping Materials using a Modal Approach - Description of the Method and Application on a Car Door Model Treated with High Damping Foam, 5th Symposium of Automobile and Railroad Comfort, Le Mans, France, Nov. 19-20, 2008.

[2] C. Faure, Identification de source vibratoire sur structure mal connue – Thèse Sci. - Université du Maine, 2016.

[3] T. Wassereau, Caractérisation de matériaux composites par problème inverse vibratoire – Thèse Sci - Université du Maine, 2016.

[4] F. Ablitzer, C. Pezerat, J.-M. Genevaux, J. Begue, , Identification of stiffness and damping properties of plates by using the local equation of motion, Journal of Sound and Vibration, Volume 333, Issue 9, 2454–2468 p, 2014

[5] Q. Leclere, F. Ablitzer, C. Pezerat, Practical implementation of the Corrected Force Analysis Technique to identify the structural parameter and load distributions, Journal of Sound and Vibration, Volume 351, Issue 1, 106-118 p, 2015.