Structural acoustic behaviour of automotive-type panels with dome shaped indentations

This paper investigates the structural–acoustic characteristics of the automotive-type panels with dome-shaped indentations. These indentations are used to increase the stiffness of the panel whilst keeping its bulk weight constant. To investigate the effect of domes upon sound radiation, four panels with different arrangements of domes are investigated numerically and experimentally. In order to improve the effect of the indentations on the panels, a structural–acoustic optimisation technique is developed. The objective function of the optimisation is to reduce the sound radiating from the panels by selecting the optimal sizing and placement of the dome-shaped indentations. The objective function, in this case, the radiated sound power from the panel, is calculated in terms of the surface velocity of the panel predicted from a finite element model. The optimisation technique assumes equi-partition of modal energy. Thus, it optimises the panel without the necessity of knowing the specific force input characteristics. Numerical and experimental results are presented for the four different intuitively designed panels, the optimised panel and a reference flat panel. It is shown that if the panel design is chosen inappropriately then the structure may radiate more sound in the frequency range of interest. However, a correctly chosen design has the ability to reduce radiated sound power without increasing the weight of the structure.