A COMPARISON OF THREE TECHNIQUES USING STEADY STATE DATA TO IDENTIFY NON-LINEAR MODAL BEHAVIOR OF AN EXTERNALLY EXCITED CANTILEVER BEAM

Non-linear system identification is used to generate models of modes in physical structures. Analysis of the theoretical non-linear model of a cantilevered beam is used to predict the inputs to the physical system that will produce responses suitable for enhanced parameter estimation, thereby improving the model. Three identification techniques are described and applied to both numerical and experimental data: the first is based on the continuous-time differential equation model of the system, the second uses relationships generated by the method of harmonic balance, and the third is based on fitting steady state response data to the amplitude and phase modulation equations resulting from a multiple time scales analysis. The performance of each method improves as the non-linearities in the system become more pronounced. The benefits and limitations of the methods are discussed.