Abstract
The loosening is thought due to bolt-nut rotation and the reduction of bolt tension due to permanent set of the fastened parts including bearing surfaces and bolt-nut or imbedding. In this study, bolt tension reduction of bolted joints with length of thread engagement of tap bolt was measured under repeated axial load. In addition, the stress distribution in bolted joints of the bolt load was investigated by the finite element analysis. As a result, it is found that imbedding decreases as the length of thread engagement increases.
