### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 4pSA1. Statistical phase analysis---The phase behavior of complex
structures.

**Richard H. Lyon
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*RH Lyon Corp., Cambridge, MA 02138
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The magnitude and phase of a transfer function are often thought of as
complementary or conjugate variables, and there may be special relationships
between them. Statistical energy analysis (SEA) is a procedure for estimating
the magnitude of a transfer function, not only of a single, directly excited
structure, but of several structures joined together. In some situations, as in
problems of machinery diagnostics and signal transmission in drill piping, the
phase of the transfer function is important in determining system performance.
If the structure is complex, a statistical estimate of the phase may be the best
one can hope for, and may also be adequate. For this reason, an investigation
has been done on the statistical properties of the phase of complex structures,
first of directly excited structures, and, recently, of joined structures to see
if some of the relatively simple results of SEA are reflected in statistical
phase analysis (SPA). This paper will review the approach taken to understanding
the phase in complex structures and some of the results thus far.