Master's Thesis Proposal

Melanie Sciammetta

(Faculty advisor: Professor Keegan Moore)

"Intermodulation Nonlinear System Identification of a Nonlinear Oscillator Under Base Excitation"

Monday, November 9

3:00 - 5:00 p.m.

Weber 200 Conference Room

Abstract: 

Intermodulation nonlinear system identification (ImNSI) is a recently developed technique for identifying the nonlinear dynamic properties of structures through excitation at two closely spaced frequencies. Although previously investigated under direct harmonic excitation, its applicability to systems subjected to base excitation has not yet been established. This work aims to extend ImNSI to nonlinear oscillators subjected to base excitation and experimentally validate its ability to identify amplitude-dependent nonlinear dynamic characteristics. The method is first adapted and investigated numerically, with its performance compared against the established direct-excitation formulation under equivalent excitation conditions. It is then implemented experimentally on a nonlinear oscillator using a moving table mounted on a long-stroke shaker. The measured response is used to identify the frequency backbone curve and amplitude-dependent energy dissipation and damping characteristics of the oscillator. These identified characteristics are then used to reconstruct the nonlinear conservative and dissipative forces and develop a nonlinear dynamic model of the experimental system. The model is evaluated by comparing its predicted response with experimental measurements to assess its ability to reproduce the observed nonlinear behavior.

Committee:
Dr. Keegan Moore (advisor), School of Aerospace Engineering
Dr. Graeme Kennedy, School of Aerospace Engineering
Dr. Bolei Deng, School of Aerospace Engineering