An experimental method to identify the effects of joints on structures using laser vibrometry

Xianghong Ma*, Alexander F. Vakakis, Lawrence A. Bergman

*Corresponding author for this work

Research output: Unpublished contribution to conferenceUnpublished Conference Paperpeer-review


A technique based on laser vibrometry is outlined for identifying the effects of bolted joints on the structural dynamics. The method is based on the comparison of the dynamics of the bolted structure to that of a "baseline" structure; e.g., a structure with similar geometry and material characteristics but no jointed interface. Hence, under identical forcing conditions, the difference in the dynamics between the actual and baseline structures can be attributed solely to the joint interface effects. Non-contacting laser vibrometry is utilized to experimentally measure these differences in the structural responses at specific frequencies. A numerical algorithm is then developed to post-process the experimental data and identify the joint effects on the dynamics. The method provides estimates for the equivalent, frequency and amplitude dependent complex modulus of the joint interface. The laser scans of the mode shapes of the systems under consideration reveal interesting dynamic phenomena such as nonlinear effects due to micro-impacts at the bolted joint as well as effects due to non-proportional damping distribution.

Original languageEnglish
Number of pages7
Publication statusPublished - 9 Sept 2001
Event18th Biennial Conference on Mechanical Vibration and Noise - Pittsburgh, PA, United States
Duration: 9 Sept 200112 Sept 2001


Conference18th Biennial Conference on Mechanical Vibration and Noise
Country/TerritoryUnited States
CityPittsburgh, PA

Bibliographical note

Funding Information:
This work is supported by a Research Grant from the Department of Energy through Sandia National Laboratories. The authors would like to thank Dr. Daniel Segalman and Dr. Jeffrey Dohner for interesting and helpful discussions on many aspects of this work.


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