Application of the wave based prediction technique for the analysis of the coupled vibro-acoustic behaviour of a 3D cavity

In the automotive industry, vehicle interior acoustics has become an important design criterion. Both legal restrictions and the growing demand for comfort, force the car manufacturers to optimize the vibro-acoustic behaviour of their products. The tendency to minimise the number of physical prototypes and to reduce the overall development cost and time, as well as the high performance of modern computer resources, clear the path for numerical prediction techniques to drive the noise, vibration and harshness optimization. The most commonly used numerical prediction techniques for vibro-acoustics are the element based methods, such as the finite element method and the boundary element method, and the statistical energy analysis method. However, the element based methods are only applicable in the lower frequency range and the statistical energy analysis method in the higher frequency range, leaving a frequency band, which is called the mid-frequency gap, for which no effective prediction technique is available at this moment. The wave based prediction technique has the potential to narrow this frequency gap. Like the element based methods, the wave based prediction technique is a deterministic technique, which is however computationally more efficient and thus suited for the mid-frequency range. This paper discusses the application of the wave based prediction technique for the vibro-acoustic analysis of a three-dimensional car-like cavity. Both uncoupled acoustic and coupled vibro-acoustic analyses are performed. A comparison with the finite element method is made with respect to convergence rate and computational efforts to show the efficiency of the new technique.