Validation of a hybrid deterministic-diffuse approach for prediction of diffuse vibration transmission across finite plate junctions

Accurate numerical prediction of vibration transmission across junctions is important since this flanking vibration transmission can have a substantial influence on the sound insulation of a system. An important parameter for quantifying vibration transmission across junctions is the coupling loss factor commonly used in Statistical Energy Analysis (SEA). A hybrid deterministicdiffuse approach is adopted here to calculate coupling loss factors across finite junctions. With this approach some parts of the structure are modelled as diffuse subsystems, for example the plates connected to the junction, while other parts, for example a connecting element, can be modelled as a deterministic subsystem. In this way the finite size and structural details of the junction are considered. The hybrid deterministic-diffuse approach is compared to Monte-Carlo simulations of a detailed finite element model where masses are randomly distributed over the plates connected to the junction and the ensemble average coupling loss factor is computed. In this validation, both direct coupling between plates and coupling through intermediate elements are considered. The coupling loss factors from both methods agree well at higher frequencies, where the diffuse field assumption is valid and no strong coupling between the out-of-plane subsystems is present.