Markowicz A., Subic A., Wang X.

The addition of damping liners to automotive panels is used to reduce noise and vibration transmitted through the car body to the occupants. Traditionally such liners are added uniformly over the exposed area of panels. Recently, some initial attempts at optimization have been performed which are now further advanced. This paper presents a novel method for optimization of damping liners in automotive panels. The main objective is to spatially redistribute liner material in an efficient manner with respect to the reduction of structural vibrations and minimizing overall weight. This is achieved by developing an optimization procedure based on genetic algorithms that explores the search space in conjunction with FEA simulation to assess the performance of various liner forms in order to identify one which approaches optimal characteristics. Experimental modal analysis is performed to validate the FEA model and also to adjust the model characteristics with respect to damping levels. In addition, design sensitivity analysis is performed in order to determine which changes in modal parameters would bring about the greatest benefits. The procedure is first tested and fine tuned on a control surface constructed using a reinforced flat plate, and then applied to a modern car bonnet and door. The flexibility of the developed optimization algorithm is demonstrated by the fact that each is performed within different manufacturing constraints. The bonnet liner is formed by pressing fiberglass and woolen layers which allows variation of density across the surface by changing the number of layers in different regions while thickness remains constant after pressing. On the other hand, various layers of viscoelastic material sheet segments are placed inside the door to vary the thickness of the treatment within the space available. The developed procedure provides scope for optimal design of automotive liners for specific material choice, manufacturing and vehicle design requirements.