Abstract
In noise and vibration control, damping treatment and isolation of structures are often applied to dissipate the energy of flexural vibrations and to reduce the transmission of energy to the surroundings. However, these treatments must be carefully designed because the present requirements of the size, power and noise levels resulting from commercial competition are very restrictive and usually there is little space to put additional material. In this paper, the statistical energy analysis (SEA) method has been used to optimize such treatment. The power balance equations have been established for a motor—fan—casing unit, and the design and possible modifications have been analysed with an SEA model. The energy transmission paths within the structure have been clearly identified and the test results confirmed the accuracy of this model. The optimum has been determined and lower noise levels have been verified by tests. A significant reduction in noise level has been achieved and the example has shown that an SEA model is very useful for analysing structures with regard to noise and vibration levels.