Vibration Measurement of Rail Stress

Measurement of thermally-induced stress in railroad rails is among the most significant issues in rail safety and track maintenance management, with implications for operation of high speed passenger trains on freight railroad trackage. Current techniques for that measurement are imprecise, time consuming, and expensive. This Innovations Deserving Exploratory Analysis (IDEA) project investigated a new technique, using rail vibrations and laser vibrometry, for the measurement of contained rail force. The concept is based on the known sensitivity of bending vibrations to contained longitudinal stress. The rail is excited at a specified frequency using an electromagnetic shaker. A laser vibrometer that is scanned along the rail is used for dynamic displacement measurements to determine the frequency and wavelength of the resulting rail vibrations. The resulting wavelength, along with the rail rigidity (which can be determined by the rail dimensions and modulus) can be used to determine contained longitudinal load. This project, together with a previous concept exploration IDEA project (HSR-30) developed the measurement technique, hardware and software to infer longitudinal rail stress loads in rail. The laboratory test results were encouraging, but did not meet the accuracy requirements established for such a system. Field tests were conducted by installing the prototype system on rail at the Transportation Technology Center, Inc., at a location that was also equipped with a strain gage system for measuring rail stress. Comparison of the strain gage data with the prototype data revealed large differences. Any further development of this concept will require an investigation of the causes of these differences and whether they can be corrected with system design changes and/or changes in the field test procedures. This report summarizes the results of the project and concludes with recommendations for further development.

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  • Supplemental Notes:
    • This HSR-IDEA project was conducted by the University of Illinois, Urbana-Champaign. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
  • Authors:
    • Weaver, Richard L
  • Publication Date: 2006-11

Language

  • English

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Filing Info

  • Accession Number: 01145895
  • Record Type: Publication
  • Report/Paper Numbers: HSR-IDEA Project 48
  • Files: TRIS, TRB
  • Created Date: Dec 4 2009 2:08PM