Investigation towards an active barrier for structure borne sound using structural intensity

Kurzfassung

Vibrations of aircraft or vehicle engines, for instance, are often transmitted by structure borne sound, leading to a significant radiation of noise inside passenger cabins. Current active vibration control concepts use either velocity or acceleration as a control source. However, these only lead to a local reduction in vibration and not necessarily to the reduction of the vibration energy flow. This study presents the implementation of current methods for structural intensity measurement with a real-time control. The work investigates one and two-dimensional structures. A reduction of energy flow in a beam structure is shown experimentally, as well as numerically for plates. The measurements are strongly influenced by theoretical simplifications concerning the composition of the structure borne waves and the quality of the sensor arrays used, i.e. the sensor spacing and the positioning accuracy. Though, sufficient accordance between numerically and experimentally estimated structural intensity can be found using methods with smaller sensor arrays. A barrier effect is shown by numerical investigations and is measured on a beam. Therefore, the control of vibration energy flow is a more effective method for a global reduction if vibration downstream the control area.