Force appropriation of nonlinear structures

L. Renson, T. L. Hill, D. A. Ehrhardt, D. A.W. Barton, S. A. Neild

Research output: Contribution to journalArticlepeer-review


Nonlinear normal modes (NNMs) are widely used as a tool for developing mathematical models of nonlinear structures and understanding their dynamics. NNMs can be identified experimentally through a phase quadrature condition between the system response and the applied excitation. This paper demonstrates that this commonly used quadrature condition can give results that are significantly different from the true NNM, in particular, when the excitation applied to the system is limited to one input force, as is frequently used in practice. The system studied is a clamped-clamped cross-beam with two closely spaced modes. This paper shows that the regions where the quadrature condition is (in)accurate can be qualitatively captured by analysing transfer of energy between the modes of the system, leading to a discussion of the appropriate number of input forces and their locations across the structure.

Original languageEnglish (US)
Article number20170880
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number2214
StatePublished - Jun 1 2018
Externally publishedYes


  • Energy transfer
  • Force appropriation
  • Nonlinear dynamics
  • Nonlinear normal modes
  • Phase quadrature

ASJC Scopus subject areas

  • General Mathematics
  • General Engineering
  • General Physics and Astronomy


Dive into the research topics of 'Force appropriation of nonlinear structures'. Together they form a unique fingerprint.

Cite this