The coupling loss factors frequently used in statistical Energy Analysis are often based on awave approach that assumes that the transmitted waves returning to the junction are uncorrelated with the directly transmitted waves. This assumption is generally not fulfilled forstructures at low frequencies where the response exhibits distinctly well separated resonances. A method is presented here for calculation of an improved coupling loss factorfor one-dimensional subsystems. By applying statistical considerations to an analyticalexpression for the net power transmission it is possible numerically to calculate an averagevalue of the ratio of reflected to incident wave amplitudes at the junction. From this ratio animproved coupling loss factor can be calculated which takes into account the re-radiationand re-injection of power which normally occurs between two reverberant fields. This improved coupling loss factor has the following features: it is valid at low modal overlap, it isindependent of the exact boundary conditions, it depends upon the loss factor of thereceiving subsystem, and its calculation is not dependent on the strength of the coupling. Toillustrate the method, a specific beam system is considered in the frequency range where themodal overlap is small. Coupling loss factors are calculated and are employed in a traditionalSEA model to predict mean square velocities for each beam element with good accuracy.
|Journal||Journal of Sound and Vibration|
|Publication status||Published - 1998|