Identifying the significance of nonlinear normal modes

• Published in: Proceedings of the Royal Society. A, Mathematical, physical, and engineering sciences Vol. 473; no. 2199; p. 20160789
• Main Authors: Hill, T. L., Cammarano, A., Neild, S. A., Barton, D. A. W.
• Format: Journal Article
• Language: English
• Published: England The Royal Society Publishing 01-03-2017
• Edition: Royal Society (Great Britain)
• Subjects: Backbone Curves; Dynamical systems; Energy Transfer; Nonlinear Normal Modes; Nonlinear systems; Resonance; Second-Order Normal Form Technique; Structural Dynamics; energy transfer; resonance; structural dynamics; backbone curves; nonlinear normal modes; second-order normal form technique
• ISSN: 1364-5021; 1471-2946
• DOI: 10.1098/rspa.2016.0789

Nonlinear normal modes (NNMs) are widely used as a tool for understanding the forced responses of nonlinear systems. However, the contemporary definition of an NNM also encompasses a large number of dynamic behaviours which are not observed when a system is forced and damped. As such, only a few NNMs are required to understand the forced dynamics. This paper firstly demonstrates the complexity that may arise from the NNMs of a simple nonlinear system—highlighting the need for a method for identifying the significance of NNMs. An analytical investigation is used, alongside energy arguments, to develop an understanding of the mechanisms that relate the NNMs to the forced responses. This provides insight into which NNMs are pertinent to understanding the forced dynamics, and which may be disregarded. The NNMs are compared with simulated forced responses to verify these findings.