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Evaluation of Ultrasonic Measurement Systems for Bolt Load Determinations.
MISSING :9 pages
The U.S. Bureau of Mines has developed ultrasonic measurement instrumentation capable of measuring strains and elongations on tensioned and untensioned mine roof bolting systems. This report evaluates the pulsed-phase-lock-loop and pulse-echo systems. The pulse-echo systems measure time of flight of a signal through the bolt. The ultrasonic instrument converts the measurement into elongations or stress. The most recent Bureau instrument development converts travel-time measurements directly into elongation, load, stress, and torque by simple data manipulation from the keyboard. Bolt preparation and instrument calibration are described in detail.
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Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division