Vibro-Acoust. Sci. Ltd., Level 5, 15 Orion Rd., Lane Cove, NSW 2066, Australia
In previous publications, the authors have proposed an approximate ``weak coupling'' formulation for mechanical power flow between arbitrary vibrational substructures. Simple numerical examples have shown this formulation asymptotes to the statistical energy analysis (SEA) result at higher frequencies, when a large population of vibratory modes contribute to the substructure energy level, in any frequency band. This paper evaluates the accuracy of the formulation at low frequencies and low-modal density by comparison with ``exact'' energy distributions derived from the dynamic stiffness method. The results indicate that weak coupling modal power formulations are more accurate than SEA predictions in this domain. The current work highlights the importance of rigid body modes of the uncoupled substructures and the phase correlation and cross coupling of force and moment power transmission components at a structural junction.