APPLICATION OF THE TIME DOMAIN FOURIER FILTER OUTPUT (TDFFO) METHOD TO THE IDENTIFICATION OF A LIGHTLY DAMPED NON-LINEAR SYSTEM WITH AN ODD-SPRING CHARACTERISTIC

This paper presents a method for experimentally identifying the parameters of a lightly damped non-linear system with an odd restoring force, as represented by the Duffing equation. It requires only a single free vibration test to determine the variation of the natural frequency with the decaying amplitude, and the identification procedure involves no approximation, as long as one can determine the system backbone curve accurately. A computer simulation and a laboratory experiment are used to demonstrate the method.