Fatigue evaluation method based on equivalent structural stress approach for bolted connections

Abstract

In this study, Fa–N curves and σn_s–N curves of bolted connections under different geometric and load parameters were obtained through tensile-shear fatigue tests. The correlation of these curves was poor and did not satisfy engineering requirements. To this end, first, an equivalent structural stress calculation model capable of accurately characterizing the stress state of a bolted connection was derived by considering the bolt load as the input condition. Subsequently, a plate-shell finite element model for bolted connections was established, and the load parameters for bolts were extracted by simulation and inputted into the equivalent structural stress calculation model to obtain the equivalent structural stress at the crack initiation position of a bolted connection. Finally, the normalized Ss–N curve of the bolted connections was fitted considering geometric and load parameters, and a fatigue evaluation method based on equivalent structural stress was designed for bolted connections. This evaluation method can act as a reference for checking the design of bolted connections and predicting their fatigue life.