GENERALIZED RANDOM DECREMENT METHOD FOR ANALYSIS OF VIBRATION DATA

The Random Decrement method used in system identification for analysis of random vibration data is considered from a rigorous mathematical p erspective. It is shown that the Random Decrement signature deviates f rom the system free vibration curve of an associated linear system, un less the corresponding input excitation is white. The error induced by approximating the system excitation by a white noise process is exami ned Further, a generalized Random Decrement signature is introduced; i t is used to estimate efficiently the auto-correlation function of an ergodic Gaussian random process. Several examples are discussed to elu cidate the theoretical developments.