Abstract
The capability to reproduce and predict with high accuracy the behaviour of a real system is a fundamental task of numerical models. In nonlinear structural dynamics, additional parameters compared to classical linear modelling, which include the nonlinear coefficient and the mathematical form of the nonlinearity, need to be identified to bring the numerical predictions in good agreement with the experimental observations. In this context, the present paper presents a method for the identification of an experimental cantilever beam with a geometrically nonlinear thin beam clamped with a prestress, hence giving rise to a softening-hardening nonlinearity. A novel nonlinear subspace identification method formulated in the frequency domain is first exploited to estimate the nonlinear parameters of the real structure together with the underlying linear system directly from the experimental tests. Then a finite element model, built from the estimated parameters, is used to compute the backbone of the first nonlinear normal mode motion. These numerical evaluations are compared to a nonlinear normal modes-based identification of the structure using system responses to stepped sine excitation at different forcing levels.
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Acknowledgements
The authors Chiara Grappasonni and Gaetan Kerschen would like to acknowledge the financial support of the European Union (ERC Starting Grant NoVib 307265).
The authors also want to thank LMS A Siemens Business for providing access to the LMS Test.Lab software.
The author Jean-Philippe Noël is a Research Fellow (FRIA fellowship) of the Fonds de la Recherche Scientifique—FNRS which is gratefully acknowledged.
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© 2014 The Society for Experimental Mechanics, Inc.
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Grappasonni, C., Noël, J.P., Kerschen, G. (2014). Subspace and Nonlinear-Normal-Modes-Based Identification of a Beam with Softening-Hardening Behaviour. In: Kerschen, G. (eds) Nonlinear Dynamics, Volume 2. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-04522-1_6
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DOI: https://doi.org/10.1007/978-3-319-04522-1_6
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