A Methodology for the Optimal Positioning of Damping Sheets On Panels

Damping sheets are widely used in the automotive industry to improve the sound insulation properties of thin metal panels (firewall, door panels, floor and trunk lid). Due to light-weighing and cost constraints, more and more focus is given to the optimization of such sheets. This paper presents an efficient methodology, which naturally fits into the industrial design process, for solving this optimization problem. Based on the structural modes of an existing body-in-white model, an energetic post-processing is performed on the panel on which the damping sheets are distributed. Specifically, the panel is automatically partitioned into patches, on which distribution matrices are assembled. Such matrices enable a fast evaluation of energetic quantities over large frequency ranges and under various loading conditions. An optimization loop is then initiated where, in each step, the frequency-averaged vibratory energy at patch level is computed under diffuse sound field loading. The weight of the damping material is constrained below a maximum value. The optimal configuration is finally validated by an accurate evaluation of the transmission loss using a refined finite element model of the damped panel. The proposed methodology is applied on a typical industrial configuration, involving a firewall panel, through the Actran software suite.