Affiliations: [a] Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Miyagi, Japan | [b] Sawada Technical Service Co., Ltd., Onomichi, Hiroshima, Japan
Correspondence:
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Corresponding author: Noritaka Yusa, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, 6-6-01-2, Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi, 980-8579, Japan. Tel.: +81 22 7956319; Fax: +81 22 7956319; E-mail:noritaka.yusa@qse.tohoku.ac.jp
Abstract: This study proposes a simple and cost-effective method to
detect bolt loosening on the basis of low-frequency vibration signals as low
as several hertz. Laboratory tests were conducted using M16 bolts connecting
two SS400 plates. The bolts were vibrated by external impulse using a test
hammer, and their vibrations were measured using accelerometers attached to
the nuts holding the bolts. The accelerometers had the lowest measuring
frequency of 0.5 Hz, and no high-pass filter was used. The results of the
tests show that one can confirm whether or not bolts have been tightened to
the rated torque quite clearly in time domain signals. Subsequent field
tests were conducted to evaluate the M42 anchor bolts in a factory, and the
results demonstrate the effectiveness of the method.
Keywords: Non-destructive testing and evaluation, vibration, accelerometer, impulse test, frequency
