• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1117-1121
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• 2011

The movable bracket structure, which is an apparatus for supplying electric power to a running electric locomotive, is applied by a repeated load during the passage of the electric locomotive. Such a repeated load becomes an excitation source that causes screws constituting the movable bracket structure to be loosened. This study was conducted on the causes and countermeasures of the bolt loosening caused by the repeated vibration using a computer simulation. As the result, a simulation model was constructed to enable the dynamic analysis of the movable bracket structure. It could be found that the principal excitation frequency range for the bolt loosening of the movable bracket structure was less than 200 Hz. In addition, the bolts are prevented from being loosened by increasing stiffness of H beams. The vibration mode of a lower band bracket is found to be triggered in a frequency range between 300 and 600 Hz. And the increase in stiffness of the lower band bracket exhibits the effect to avoid the bolt loosening at a frequency range of 200 Hz or more.