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On High SEAs (Statistical Energy Analysis)
Statistical Energy Analysis is a system-based approach in which vibration and noise problems are formulated as an interaction between several interconnected subsystems. SEA consists of computing the time and space-averaged response of each system, so that the equations used for predicting the response depend mainly on the gross properties of the system viz. geometry, material properties and the manner in which they are connected to other subsystems (welding, riveting etc.)

Important parameters derived from the above properties, for predicting noise and vibration are, modal density and coupling loss factor. The former represents number of resonance frequencies of a vibratory or acoustic system in a given frequency band (which is a measure of the energy potential). The latter quantifies the rate of energy flow between subsystems. The damping factor quantifies the rate of energy dissipation in each system. Modal density and coupling loss factor can be calculated for a number of simple situations. For complex structures, they can be obtained by experimental measurements. However, damping factors can be obtained only from experiments.

Much of the work enlisted under consultation/sponsored projects mentioned above has involved the application of SEA. At present, research is being conducted for using the SEA technique in reduction of diesel engine noise. A photograph of an experimental setup to measure dynamic characteristics of a connecting rod is shown in Figure 1.