Affiliations: Department of Mechanical and Energy Systems Engineering, Oita University, Oita, Japan
Correspondence:
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Corresponding author: Yuji Gotoh, Department of Mechanical and Energy Systems Engineering, Oita University, Oita 870-1192, Japan. Tel.: +81 97 554 7795; Fax: +81 97 554 7790; E-mail:goto-yuuji@oita-u.ac.jp
Abstract: The development of the inspection technique of detecting
the slack of the high tension bolt is desired. The permeability inside the
side of the bolt head is changed since the bolt head is compressed by
bolting a plate. Therefore, the evaluation of the slack of the bolt is
possible by detecting the difference of the magnetic characteristics. In
this paper, the inspection method for measuring the slack of the steel
high-tension bolt of hexagon head using a small electromagnetic
non-contacting sensor is proposed. The distribution of stress, flux density
and eddy current density near the bolt head is estimated by 3-D nonlinear
electromagnetic finite element method (FEM) analysis taking account of the
electromagnetic property under various compressive stresses. The results
showed that the non-destructive inspection of the slack of the high-tension
bolts is possible by detecting the change of flux density in the side of the
bolt head.
Keywords: Slack of the high tension bolt, compressive stress, non-destructive inspection, 3-D stress FEM, 3-D nonlinear electromagnetic FEM, B-H curve
