A theoretically and numerically investigation of active control of structural sound radiation in the independent modal space has been performed. The one by one corresponding relationship between structural mode and sound radiation mode is been proved. The structure-acoustic coupling control equation is deduced in the decoupling independent modal space. According to H∞control, numerical simulation of active control of sound radiation from plate is realized by FEM/BEM method based on structure-acoustic coupling control equation. The structure-acoustic coupling control method put forward in this article gives better control results of structural vibration and sound radiation compared with the control results obtained from independent modal space method(IMSC).
Active structural acoustic control is to modify the vibration of the partitions and thus reduce the sound radiation(Fuller, 1990). According to mode theory, ASAC methods can be divided into two category: One method is based on the vibration mode of structure. The control of sound radiation from structure by vibration mode utilize the mechanism of modal suppression, the control force was put on the position of maximum responses of vibrate to suppress the structural vibrate, then the sound radiation power was reduced. But, if the control of structural sound radiation is in the vibration modal space, the control law will be hard to design due to the non-independent of each order of vibration modal. The other sound radiation control method is based on the radiation mode. When the sound radiation control method is based on the vibration mode of structure, the response of the structure can be reduced but the sound radiation power is not always to be reduced, sometimes it could be increased. This let it to be necessary to understand the relationship between the structure and acoustic field better. Borgiotti(1990), Curfare(1991), Elliott(1993) Baumann(1991) Synder(1993) carry out some research work on this, the results shows: a set of mode coordinates can be find to decompose the vibration of a surface into a number of velocity distributions which radiate sound independently.
