Helicopter rotor aeroelastic stability evaluation using Lyapunov Exponents

Aykut Tamer, Pierangelo Masarati

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding

8 Citations (SciVal)


This work presents the application of Lyapunov Characteristic Exponents (LCEs), or in short Lyapunov Exponents, to the evaluation of rotorcraft aeroelastic stability. Current state of art literature on rotorcraft aeroelastic stability analysis approaches the problem by either using a constant coefficient approximation or by computing the eigenvalues of the monodromy matrix according to Floquet Theory. The former neglects periodicity and the latter is only applicable to the perturbation of the problem about a periodic orbit. Often such approximations are acceptable; however, LCEs can be applied to generic trajectories of non-linear systems to produce an estimate of the stability properties without the need to reach a steady orbit or determine the period of the system. Being more general, LCEs can provide a common environment in rotorcraft aeroelastic stability among both linear and non-linear systems, and be applicable to all problems that can be proficiently analyzed by time marching analysis, including experimental data. This work presents the evaluation of the stability of an isolated rotor formulated as a linear time-periodic system by computing the LCEs from arbitrary fiducial trajectories. The method is illustrated in relation with the problem of rigid helicopter blade flapping, and ground resonance with one damper inoperative and with non-linear dampers.

Original languageEnglish
Title of host publication40th European Rotorcraft Forum 2014
PublisherRoyal Aeronautical Society
Number of pages9
ISBN (Electronic)9781510802568
Publication statusPublished - 31 Dec 2014
Event40th European Rotorcraft Forum, ERF 2014 - Southampton, UK United Kingdom
Duration: 2 Sept 20145 Sept 2014

Publication series

Name40th European Rotorcraft Forum 2014


Conference40th European Rotorcraft Forum, ERF 2014
Country/TerritoryUK United Kingdom

ASJC Scopus subject areas

  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Instrumentation
  • Control and Systems Engineering


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