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Forty Years of Use and Abuse of Impact Testing: A Practical Guide to Making Good FRF Measurements

  • David L. Brown
  • Randall J. AllemangEmail author
  • Allyn W. Phillips
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)

Abstract

Impact testing first came into common use over 40 years ago, once the fast Fourier transform (FFT) was commercially available. Over this period of time, implementation of impact testing has evolved but some of the same problems seem to reoccur. This paper documents the practical guidelines that have evolved, along with some practical examples of what happens when the guidelines are not followed, particularly with respect to overload detection and related errors. In particular, the ADC hardware differences are noted and the distortion problem associated with overloads is thoroughly reviewed. Other issues that are discussed include factors that affect force spectrum, impact hammer calibration, double impacting, use, application and correction for exponential windows and understanding how the time truncation causes leakage for a realistic case involving a lightly damped structural system.

Keywords

Impact test Hammer test Overload Exponential window Double impact ADC issues 

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Copyright information

© The Society for Experimental Mechanics, Inc. 2015

Authors and Affiliations

  • David L. Brown
    • 1
  • Randall J. Allemang
    • 1
    Email author
  • Allyn W. Phillips
    • 1
  1. 1.Structural Dynamics Research Lab, Department of Mechanical and Materials Engineering, College of Engineering and Applied ScienceUniversity of CincinnatiCincinnatiUSA

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