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Nonlinear Modal Analysis for Non-conservative Nonlinear Systems
Release time:December 3, 2020

Topic: Nonlinear Modal Analysis for Non-conservative Nonlinear Systems

Speaker: Dr. Sun Yekai, Imperial College London

Time: Saturday, December 5, 2020, 14:30 - 16:30

Venue:Main Building F912, Shahe Campus


The dynamic analysis of systems with nonlinearities has become an important topic in many engineering fields. Apart from the forced response analyses, nonlinear modal analysis has been successfully extended to such non-conservative systems thanks to the definition of damped nonlinear normal modes. The energy balance method is a tool that permits to directly predict resonances for a conservative system with nonlinearities from its nonlinear modes. In this presentation, the energy balance method is extended to systems with non-conservative nonlinearities using the concept of the damped nonlinear normal mode and its application in a full-scale engineering structure. This extended method consists of a balance between the energy loss from the internal damping, the energy transferred from the external excitation, and the energy exchanged with the non-conservative nonlinear force. The method assumes that the solution of the forced response at resonance bears resemblance to that of the damped nonlinear normal mode. One illustrative model and a full-scale structure with dissipative nonlinearities as well as Hoffmann model showing self-excited vibration are tested using the method. In each testcase, resonances are predicted efficiently and the computed force amplitude curves show a great agreement with the forced responses. In addition, the self- excited solutions and isolas in forced responses can be effectively detected and identified. The accuracy and limitations of the method have been critically discussed in this work.

Biography of the Speaker:

Sun Yekai is a PhD candidate at Imperial College London. He graduated with first class honors from Aerospace Engineering Department, University of Bristol in 2017. His research interests mainly include nonlinear dynamic analysis, nonlinear modal analysis, resonance prediction of nonlinear forced response, analysis and design of friction damper, etc.

School of Energy and Power Engineering