Nonlinear Modal Testing: A Phase Resonance Approach using Controlled Excitation by Maren Scheel, May 2022

Nonlinear Modal Testing: A Phase Resonance Approach using Controlled Excitation

Maren Scheel

University of Stuttgart, Stuttgart, Germany

May 10, 2021

Abstract:

In contrast to linear modes, the parameters of a nonlinear mode, i.e., modal frequency, damping ratio, and deflection shape, depending on the vibration level. This is why standard methods for experimental modal analysis fail in the presence of nonlinearity. In the last years, scientists have explored opportunities to extend modal testing to nonlinear systems. This talk provides an overview of some promising approaches to identifying the amplitude-dependent parameters of an isolated mode. We will then discuss the phase resonance approach in more detail. Phase resonance can be conveniently ensured using a phase controller, for example, the phase-locked loop (PLL). By controlling the excitation, one can measure the backbone of the mode and extract the modal properties. This approach is very robust, and the modal properties accurately capture steady-state dynamics around the resonance, even in presence of strong stiffness and damping nonlinearities. While the main part of the talk focuses on single-point excitation, an extension to base excitation is sketched.

Biography:

Maren Scheel is a research associate and PhD student at the University of Stuttgart, Germany. She joined the group of Prof. Malte Krack in 2016. Her research focuses on the development of experimental methods for nonlinear modal testing. Maren obtained her Master’s degree in mechanical engineering from the University of Stuttgart.