Loosening Test of a Bolted Joint by Axial Impact Load

Abstract

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 are 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, regarding the axial impact load, the impact load of the hexagon bolt and hexagon nut with flange increased and the impact load of Active-X bolts and nuts decreased compared to the hexagon bolt and hexagon nut. Furthermore, regarding the amount of decrease in axial force after impact, the decrease in axial force was alleviated for hexagon bolts and hexagon nuts with flanges and Active-X bolts and nuts compared to hexagon bolts and hexagon nuts.