modal testing; free-play; non-linear resonant decay method; identification of non-linearties
Abstract :
[en] Structural non-linearities are becoming of increasing importance in determining the performance of a range
of vibrating mechanical structures. As a consequence, the identification of systems with non-linearities is
starting to become a necessary part of vibration testing procedures. NL-RDM (Non-Linear Resonant Decay
Method) is an approach for the identification of non-linear multi-degree of freedom systems in modal
space on a mode by mode basis, using an appropriated sine excitation to isolate modes or groups of modes.
However, the application of NL-RDM to a multi-degree of freedom system with a discontinuous free-play
non-linearity has not been attempted yet, except to treat it using high order polynomial terms. The difficulty
of using NL-RDM when seeking a discontinuous free-play model lies in the choice of the so-called underlying
linear model to be used in uncoupling the linear equations. In this paper, a simulated two degree of
freedom lumped parameter system with a free-play non-linearity
G. Kerschen, K. Worden, A. F. Vakakis, and J. C. Golinval. Past, present and future of nonlinear system identification in structural dynamics. Mechanical system and signal processing, 20:505-592, 2006.
J. R. Wright, M. F. Platten, J. E. Cooper, and M. Sarmast. Identification of multi-degree of frerdom weakly non-linear systems using a model based in modal space. In International Conference on Structural System Identification, pages 49-68, Kassel, Germany, September 2001.
M. F. Platten, J. R. Wright, and J. E. Cooper. Identification of a multi-degree of freedom nonlinear simulated and experimental system. In Proceedings of the international seminar on modal analysis, pages 1195-1202, Leuven, Belgium, September 2002.
P. Verboven. Frequency domain system identification for modal analysis. PhD thesis, Vrije University, Brussel, Belgium, 2002.
P. S. Holmes. Advanced applications of normal mode testing. PhD thesis, University of Manchester, Manchester, UK, 1996.
M. J. Desforges, J. E. Cooper, and J. R. Wright. Force appropriation for flight flutter testing. Journal of Aerospace Engineering, Part G, 218:1-10, 2004.
K. Worden and G. R. Tomlinson. Nonliearity in structural dynamics: detection, identification and modelling. Published by institute of physics publishing, London, England, 2001.
B. Peeters, H. Van der Auweraer, P. Guillaume, and J. Leuridan. The polymax frequency- domain method: a new standard for modal parameter estimation? Shock and Vibration, 11:395-409, 2004.
S. Naylor. Identification of non-proportionally damped structures using force appropriation. PhD thesis, University of Manchester, Manchester, UK, 1998.
