NVH development of car structures by means of numerical simulation of energetic quantities

For the future development of vehicles the analysis of NVH (noise, vibration, and harshness) properties in early development stages is a differentiating competitive factor. In order to achieve a maturity level of products as early as possible, a prediction of the NVH properties based on numerical simulation is required. An approach to achieve this goal is to analyze the energetic chain of effects, which reaches from the excitation of a structure via structure-borne sound via sound radiation to airborne sound. The chain link of structure-borne sound along the energetic chain of effects is represented by the structural intensity (STI). The vibratory energy flow through a structure can be analyzed by means of the STI, which allows for influencing the energy propagation. In order to completely describe a system with fluid-structure interaction, the simulation of the fluid around a structure must be integrated in the numerical simulation of the STI. Based on this system the cause-effect relationship between the STI and the surrounding fluid can be analyzed and characterized. In this paper the STI calculation is extended by calculation of the SI of the surrounding fluid and analyzed for the radiation of the structure. The goal is to identify the dependencies between the STI and the sound radiation into the surrounding fluid. Afterwards, the generality of dependencies between the STI, the radiated sound, and the fluid as well as the transferability to complex structures are discussed.