Loosening of steel threaded connection subjected to axial compressive impact loading

Abstract Loosening of threaded connection under impact loading is important in engineering structures such as the fuze on a projectile. It is difficult to predict the loosening behavior of threaded connection under impact loading due to their high nonlinearities introduced by friction and discontinuity. This paper investigated the loosening response of a threaded connection under a series of impact loadings using Hopkinson bar experiments. The loosening phase diagram was constructed by measuring the preload variation. The correlation between the preload variation and the loosening rotation angle was established by using high speed camera and digital image correlation technique. A 3D finite element model was developed to analyze the loosening mechanism of threaded connection. The transient behavior of threaded connection shows a tightening-loosening alternation process. This study provides an understanding of the loosening process of threaded connection under impact loading and is helpful for optimizing structural design under extreme conditions.