Richard H. Lyon
RH Lyon Corp., Cambridge, MA 02138
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.