An investigation on the effect of thread pitch on the self-loosening of bolted joint caused by fretting wear

Abstract

To study the effect of thread pitch on the bolt loosening behavior with consideration of fretting wear, the loosening experiments and finite element analysis were carried out to the bolts with different thread pitches. The experimental results demonstrate that fretting wear existed on the thread surface. It caused a slow bolt loosening without the nut rotation. With the thread pitch increases, the clamping force will become smaller, so that the fretting wear on the thread surface will also decrease, indicating that lager thread pitch could increase the anti-loosening ability through alleviating the fretting wear. The FE (Finite Element) results show that the decrease of sliding distance on thread surface had more beneficial effects than the increase of contact stress on the reduction in the fretting wear for the bolt with larger thread pitch.