ボルト軸方向衝撃荷重によるねじ締結体のゆるみ試験

（座面陥没と軸力に関する検討）

抄録

Loosening of the screw can be classified into types depending on the cause and the phenomenon, there is a "loose by the fluctuation of the axial load" as one of them. Loosening mechanism according to fluctuation the axial load is the sliding of the bearing surface caused by sliding of the threaded portion by fluctuation the axial force and a rotation of the nut by torsion torque accumulated in the bolt shaft. In this study, the effect of preventing "loosening due to changes in axial load" of bolts and nuts that have been developed aimed at loosening prevention effect was investigated from these viewpoints. As a result, the axial impact load decreased the most for Active-X bolts and nuts compared to other conditions. In addition, the amount of reduction in axial force after impact is also the smallest for the Active-X bolt and nut among the four conditions. From the above, it is considered that both the magnitude of the impact load and the amount of depression of the bearing surface affect the reduction in axial force due to the axial impact load.