Investigations on the fretting fatigue failure mechanism of bolted joints in high strength steel subjected to different levels of pre-tension

Bolted connections are widely used as an effective joining method with higher fatigue strength than equivalent welded and riveted joints. The fretting fatigue problem caused by components in contact subjected simultaneously to fluctuating loads and relative small movements is of special importance in the vicinity of bolted joints. In the present paper, a series of fatigue tests on bolted connections using moderately thick plates made of high strength steel S500MC carried out using different pre-tension levels is described. It was shown that fretting fatigue decreased when a higher pre-tension force is used. In addition, a 3D finite element model was built to assess the stress gradient in the connection and several multiaxial criteria were used to determine the location of the initial crack. These numerical results were correlated to the experimental results and showed acceptable predictions.