Random Decrement Signal Processing of Modal Impact Test Data

  • Rune Brincker
  • Anders Brandt
Conference paper
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)


When performing modal impact tests on mechanical systems many practioners utilize hardware based digital signal processors to rapidly estimate average spectral properties from a set of repeated impact and response time traces. However, if the complete set of time traces is saved as is commonly done when performing impact tests on civil structures then more generalized analysis and triggering conditions can be used to process the dataset. One such more general triggering condition can be referred to as random decrement signal processing. In this paper it is explained and illustrated how random decrement signal processing can be used to accept double hit impact and overlapping responses and it is shown that in many cases, the estimated transfer function are estimated with higher accuracy then using traditional triggering/averaging techniques.


Frequency Response Function Experimental Mechanics Time Trace Trigger Condition Civil Structure 
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  1. [1]
    Rasmussen, J.C. and Brincker, R.: Estimation of Frequency Response Functions by Random Decrement. Proc 14th International Modal analysis Conference, Dearborn, Michigan, USA, Feb. 12–15, 1996, pp. 246–252.Google Scholar
  2. [2]
    Brincker, R. and Rasmussen, J.C.: Random Decrement Based FRF Estimation. Proc 15th International Modal analysis Conference, Orlando, Florida, USA, Feb. 3–6, 1997, pp. 1571–1576.Google Scholar
  3. [3]
    Rasmussen, J.C. Modal Analysis Based on the Random Decrement Technique. Ph.D. Thesis, Aalborg University, Department of Building Technology and Structural Engineering, 1997.Google Scholar

Copyright information

© Springer Science+Businees Media, LLC 2011

Authors and Affiliations

  • Rune Brincker
    • 1
  • Anders Brandt
    • 1
  1. 1.Department of Industrial and Civil EngineeringUniversity of Southern DenmarkOdense MDenmark

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