THE ROLE AND EXPERIMENTAL DETERMINATION OF EQUIVALENT MASS IN COMPLEX SEA MODELS

The application of statistical energy analysis to vibro-acoustic systems of complex geometry has been made practicable by the introduction of the concept of equivalent mass/equivalent volume. Although previous research at the ISVR has shown that these parameters can be directly measured, it has recently been found that the published formulae for carrying out this calculation are not sufficiently accurate. This is because it has been previously incorrectly assumed that the measurement on the subsystem of interest is unaffected by the presence of other attached subsystems. The paper derives the correct expressions for equivalent mass/equivalent volume for the general case of N -connected subsystems. By utilizing these derived expressions, the paper then proceeds to show that the coupling loss factors can be obtained directly in terms of the measured input power and vibration velocity/sound pressure. The paper concludes by showing that the power balance equations can, by utilizing the above expressions, be framed in terms of the subsystem velocities/sound pressures rather than in terms of subsystem energies.