EVALUATING THE DYNAMICAL RESPONSE VARIABLES

This chapter focuses on the methods for representing the energy distribution, converting the energy to other variables, and for calculating the variance and confidence levels of the response variables. In the statistical energy analysis (SEA) model, the average energy levels are distributed in space and frequency. For an excitation in a given frequency range, the energy levels vary from subsystem to subsystem and over the spatial extent of the system. In a narrow band frequency analysis such as obtained by a fast Fourier transform, the frequency bands have a constant width. Presented as a power spectrum, the amplitude of a broad band response is proportional to the bandwidth. The total energy of a subsystem is not the primary quantity solved for in the SEA equations. This is because the power flow between subsystems is proportional to the difference in modal energy.