A Note on Modal Summations and Averaging Methods As Applied to Statistical Energy Analysis (S.E.A.)
✍ Scribed by A.J. Keane
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 392 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0022-460X
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✦ Synopsis
In this note the power transmission between two, point spring coupled, axially vibrating rods under various conditions is examined. The effects of using a modal description for the rods, are examined, with particular attention being paid to the number of modes used when assessing energy flows. Also considered are the various methods commonly used to calculate the average energy flows for this system. These studies have been carried out as part of a larger study on variability in S.E.A. predictions for more complex models. The differences between the averaging methods used are shown to be significant and demonstrate the inherent dangers of assuming that frequency and ensemble averages are equivalent, a common assumption of traditional S.E.A. The adoption of a modal description for the system being studied is seen to be sustainable provided that the correct number of modes is used within the calculations. This number rises with coupling strength and also if the point of coupling shows model coherence (such as occurs at the ends of a free-free rod). These results lend credence to the adoption of modal methods when studying S.E.A. but indicate that frequency averaging should be handled with care.