Order reduction of parametrically excited nonlinear systems subjected to external periodic excitations

Sangram Redkar, S. C. Sinha

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

In this work, some techniques for order reduction of nonlinear systems with periodic coefficients subjected to external periodic excitations are presented. The periodicity of the linear terms is assumed to be non-commensurate with the periodicity of forcing vector. The dynamical equations of motion are transformed using the Lyapunov-Floquet (L-F) transformation such that the linear parts of the resulting equations become time-invariant while the forcing and/or nonlinearity takes the form of quasiperiodic functions. The techniques proposed here; construct a reduced order equivalent system by expressing the non-dominant states as time-varying functions of the dominant (master) states. This reduced order model preserves stability properties and is easier to analyze, simulate and control since it consists of relatively small number of states in comparison with the large scale system. Specifically, two methods are outlined to obtain the reduced order model. First approach is a straightforward application of linear method similar to the 'Guyan reduction', the second novel technique proposed here, utilizes the concept of 'invariant manifolds' for the forced problem to construct the fundamental solution. Order reduction approach based on invariant manifold technique yields unique 'reducibility conditions'. If these 'reducibility conditions' are satisfied only then an accurate order reduction via 'invariant manifold1 is possible. This approach not only yields accurate reduced order models using the fundamental solution but also explains the consequences of various ''primary' and 'secondary resonances' present in the system. One can also recover 'resonance conditions' associated with the fundamental solution which could be obtained via perturbation techniques by assuming weak parametric excitation. This technique is capable of handing systems with strong parametric excitations subjected to periodic and quasi-periodic forcing. These methodologies are applied to a typical problem and results for large-scale and reduced order models are compared. It is anticipated that these techniques will provide a useful tool in the analysis and control system design of large-scale parametrically excited nonlinear systems subjected to external periodic excitations.

Original languageEnglish (US)
Title of host publicationProceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009
Pages709-718
Number of pages10
EditionPART B
DOIs
StatePublished - Jun 24 2010
Event2009 ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, DETC2009 - San Diego, CA, United States
Duration: Aug 30 2009Sep 2 2009

Publication series

NameProceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009
NumberPART B
Volume4

Conference

Conference2009 ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, DETC2009
CountryUnited States
CitySan Diego, CA
Period8/30/099/2/09

Keywords

  • L-F transformation
  • Nonlinear time periodic forced systems
  • Order reduction

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Hardware and Architecture
  • Electrical and Electronic Engineering

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