Statistical energy analysis of periodically stiffened damped plate structures

Stiffened panels are used widely in aerospace and marine vehicles, and it is often necessary to predict high frequency noise and vibration levels in structures of this type. The present work is concerned with modelling high frequency vibration transmission through a stiffened panel within the context of Statistical Energy Analysis (SEA). It is proposed that the panel can be modelled as a damped coupling element between two adjoining structural components, and the transmission and absorption coefficients calculated on the basis of periodic structure theory. The method is applied to the forced response of two panels which are coupled by a stiffened panel and a comparison is made with (i) exact results obtained by using the dynamic stiffness method, (ii) results yielded by a conventional SEA approach, and (iii) results yielded by wave intensity analysis (WIA). The method is found to yield accurate response predictions which are a significant improvement upon the conventional SEA and WIA results obtained for the example system. Previous work has shown that vibration transmission through a periodic system can be very sensitive to structural disorder, and the present study includes an investigation of the effects of disorder in the stiffener spacing. (C) 1997 Academic Press Limited.