A power flow analysis has been developed for predicting the vibration response of dynamic systems to high frequencies at which the traditional finite element method is no longer practical. As compared to Statistical Energy Analysis, which predicts an overall vibration response of each dynamic subsystem, the power flow analysis enables one to predict the spatial variation of the vibration response within each subsystem, as well as the power flow and vibration response throughout the entire system. The formulation of the power flow analysis is based on a differential, control-volume approach and is shown to result in a partial differential equation of the heat conduction type which can be solved by applying the finite element method. Example applications to (1) an uncoupled beam and (2) two coupled beams are presented to illustrate the analysis.

Knock is known to cause acoustical cavity resonances in the combustion chambers of engines. Understanding this phenomenon is important for control of engine noise and optimization of knock-detection systems. Cavity resonances were investigated in detail for six open-chamber diesel engines of different sizes. Spectral data were obtained from cylinder pressure-time traces and compared with predictions from finite-element calculations of the cavity resonances. Good agreement was found.

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An analytical method is developed for predicting vehicle interior noise and identifying noise sources. In this method, the finite element models representing the vehicle structure and its enclosed acoustic cavity are coupled mathematically. A modal formulation is employed to solve for the interior acoustic response, and an analysis is developed to identify the structural and acoustic modal participation as well as the boundary panel participation in producing the response. As an example application, a coupled model of an automotive vehicle is presented and experimentally evaluated. The modal and panel participations are identified from the results.

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