Radiated sound power of automotive-type panels with dome-shaped indentations

The automotive industry has witnessed a trend in recent years of reducing the bulk weight of a vehicle in order to achieve economical fuel consumption. Unfortunately, reduced bulk weight often compromises the noise, vibration and harshness (NVH) characteristics of the vehicle. This paper investigates the effect of using dome-shaped indentations on a flat panel in order to reduce the sound radiation whilst keeping the weight of the panel constant. The dimensions and placement of the dome-shaped indentations are numerically optimized using a genetic algorithm technique so that the panel radiates minimum sound power in the frequency range of interest. Both numerical and experimental tests are performed on the optimized panel which is then compared to the radiated sound power of an equivalent flat panel. Tests were also performed on intuitively placed domes on the panels. The results illustrate the fluctuation in radiated sound power by varying the number and location of the dome-shaped indentations. The paper concludes by demonstrating the advantages of a fast and user-friendly optimization approach to passive noise control problems.