Abstract
Broadband impact excitation in structural dynamics is a common technique used to detect and characterize nonlinearities in mechanical systems since it excites many frequencies of a structure at once. Non-stationary time signals from transient ring-down measurements require time-frequency analysis tools to observe variations in frequency and energy dissipation as the response evolves. This work uses the short-time Fourier transform to estimate the instantaneous parameters from measured or simulated data. By combining the discrete Fourier transform with an expanding or contracting window function that moves along the time axis, the resulting spectra are used to estimate the instantaneous frequencies, damping ratios and complex Fourier coefficients. This method is demonstrated on a multi-degree-of-freedom beam with a cubic spring attachment. The amplitude-frequency dependence in the damped response is compared to the undamped nonlinear normal modes. A second example shows the results from experimental ring-down measurements taken on a beam with a lap joint, revealing how the mechanical interface introduces nonlinear frequency and damping parameters.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Cooley, J.W., Tukey, J.W.: An algorithm for the machine calculation of complex Fourier series. Math. Comput. 19, 297–301 (1965)
Neild, S.A., McFadden, P.D., Williams, M.S.: A review of time-frequency methods for structural vibration analysis. Eng. Struct. 25, 713–728 (2003)
Feldman, M.: Non-linear system vibration analysis using Hilbert transform–I. Free vibration analysis method ‘Freevib’. Mech. Syst. Signal Process. 8, 119–127 (1994)
Sumali, H., Kellogg, R.A.: Calculating damping from ring-down using Hilbert transform and curve fitting. Presented at the 4th International Operational Modal Analysis Conference (IOMAC), Istanbul, Turkey, May 2011
Sracic, M.W., Allen, M.S., Sumali, H.: Identifying the modal properties of nonlinear structures using measured free response time histories from a scanning laser Doppler vibrometer. In: Topics in Nonlinear Dynamics, Conference Proceedings of the Society for Experimental Mechanics Series, vol. 3, pp. 269–286. Springer (2012)
Deaner, B.J., Allen, M.S., Starr, M.J., Segalman, D.J., Sumali, H.: Application of viscous and Iwan modal damping models to experimental measurements from bolted structures. J. Vib. Acoust. 137, 021012 (2015)
Londoño, J.M., Neild, S.A., Cooper, J.E.: Identification of backbone curves of nonlinear systems from resonance decay responses. J. Sound Vib. 348, 224–238 (2015)
Huang, N.E., Shen, Z., Long, S.R., Wu, M.C., Shih, H.H., Zheng, Q., et al.: The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. In: Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, pp. 903–995. (1998)
Eriten, M., Kurt, M., Luo, G., McFarland, D.M., Bergman, L.A., Vakakis, A.F.: Nonlinear system identification of frictional effects in a beam with a bolted joint connection. Mech. Syst. Signal Process. 39, 245–264 (2013)
Lee, Y., Vakakis, A., McFarland, D., Bergman, L.: A global–local approach to nonlinear system identification: a review. Struct. Control Health Monit. 17, 742–760 (2010)
Vakakis, A., Bergman, L., McFarland, D., Lee, Y., Kurt, M.: Current efforts towards a non-linear system identification methodology of broad applicability. In: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011
Kurt, M., Eriten, M., McFarland, D.M., Bergman, L.A., Vakakis, A.F.: Methodology for model updating of mechanical components with local nonlinearities. J. Sound Vib. 357, 331–348 (2015)
Kerschen, G., Peeters, M., Golinval, J.C., Vakakis, A.F.: Nonlinear normal modes. Part I. A useful framework for the structural dynamicist. Mech. Syst. Signal Process. 23, 170–194 (2009)
Vakakis, A.F.: Non-linear normal modes (NNMs) and their applications in vibration theory: an overview. Mech. Syst. Signal Process. 11, 3–22 (1997)
Panagopoulos, P., Georgiades, F., Tsakirtzis, S., Vakakis, A.F., Bergman, L.A.: Multi-scaled analysis of the damped dynamics of an elastic rod with an essentially nonlinear end attachment. Int. J. Solids Struct. 44, 6256–6278 (2007)
Peeters, M., Kerschen, G., Golinval, J.C.: Dynamic testing of nonlinear vibrating structures using nonlinear normal modes. J. Sound Vib. 330, 486–509 (2011)
Peeters, M., Kerschen, G., Golinval, J.C.: Modal testing of nonlinear vibrating structures based on nonlinear normal modes: experimental demonstration. Mech. Syst. Signal Process. 25, 1227–1247 (2011)
Ardeh, H., Allen, M.: Investigating cases of jump phenomenon in a nonlinear oscillatory system. In: Topics in Nonlinear Dynamics, Conference Proceedings of the Society for Experimental Mechanics Series, vol. 1, pp. 299–318. Springer, New York, 2013
Kuether, R.J., Renson, L., Detroux, T., Grappasonni, C., Kerschen, G., Allen, M.S.: Nonlinear normal modes, modal interactions and isolated resonance curves. J. Sound Vib. 351, 299–310 (2015)
Peeters, M., Viguié, R., Sérandour, G., Kerschen, G., Golinval, J.C.: Nonlinear normal modes, Part II: toward a practical computation using numerical continuation techniques. Mech. Syst. Signal Process. 23, 195–216 (2009)
Shaw, S.W., Pierre, C.: Normal modes for non-linear vibratory systems. J. Sound Vib. 164, 85–124 (1993)
Ehrhardt, D., Harris, R., Allen, M.: Numerical and experimental determination of nonlinear normal modes of a circular perforated plate. In: Topics in Modal Analysis I, Conference Proceedings of the Society for Experimental Mechanics, vol. 7, pp. 239–251. Series Springer International Publishing, 2014
Ardeh, H.A.: Geometrical theory of nonlinear modal analysis. Ph.D Dissertation, University of Wisconsin-Madison (2014)
Brake, M., Reuss, P., Segalman, D., Gaul, L.: Variability and repeatability of jointed structures with frictional interfaces. In: Dynamics of Coupled Structures, Conference Proceedings of the Society for Experimental Mechanics Series, vol. 1, pp. 245–252. Springer International Publishing (2014)
Smith, S., Bilbao-Ludena, J.C., Catalfamo, S., Brake, M.R.W., Reuß, P., Schwingshackl, C.W.: The effects of boundary conditions, measurement techniques, and excitation type on measurements of the properties of mechanical joints. In: Nonlinear Dynamics, Conference Proceedings of the Society for Experimental Mechanics Series, vol. 1, pp. 415–431. Springer International Publishing (2016)
Bonney, M., Robertson, B., Schempp, F., Brake, M.R.W., Mignolet, M.: experimental determination of frictional interface models. Presented at the 34th International Modal Analysis Conference (IMAC XXXIV), Orlando, 2016
Catalfamo, S., Smith, S.A., Morlock, F., Brake, M.R.W., Reuß, P., Schwingshackl, C.W., et al.: Effects of experimental methods on the measurements of a nonlinear structure. Presented at the 34th International Modal Analysis Conference (IMAC XXXIV), Orlando, 2016
Salles, L., Swacek, C., Lacayo, R.M., Reuss, P., Brake, M.R.W., Schwingshackl, C.W.: Numerical round robin for prediction of dissipation in lap joints. In: Nonlinear Dynamics, Conference Proceedings of the Society for Experimental Mechanics Series, vol. 1, pp. 53–64. Springer International Publishing (2016)
Gross, J., Armand, J., Lacayo, R.M., Reuß, P., Salles, L., Schwingshackl, C.W., et al.: A numerical round robin for the prediction of the dynamics of jointed structures. Presented at the 34th International Modal Analysis Conference (IMAC XXXIV), Orlando, 2016
Acknowledgements
This work was funded by Sandia National Laboratories. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. The authors would also like to thank Matt Bonney, Brett Robertson and Fabian Schempp for sharing the experimental data they collected on the lap joint presented in Sect. 24.4. Finally, the authors would like to thank Scott Smith and Caroline Nielsen for their help developing the algorithm in Matlab and working on a graphical user interface.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2016 The Society for Experimental Mechanics, Inc.
About this paper
Cite this paper
Kuether, R.J., Brake, M.R.W. (2016). Instantaneous Frequency and Damping from Transient Ring-Down Data. In: Allen, M., Mayes, R., Rixen, D. (eds) Dynamics of Coupled Structures, Volume 4. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-29763-7_24
Download citation
DOI: https://doi.org/10.1007/978-3-319-29763-7_24
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-29762-0
Online ISBN: 978-3-319-29763-7
eBook Packages: EngineeringEngineering (R0)