Abstract:The structural high-strength (HS) rivet demonstrated advantages including preload stability and excellent resistance to the loosening, fatigue and delayed fracture. Thus, the HS rivet has become a promising alternative to the HS bolt currently employed in the ring-flange connection of wind turbine towers. However, relevant studies are still lacked and required on the fatigue performance of HS rivets in ring-flange connections. The work carried out comparative model fatigue tests and refined numerical analysis on the ring-flange connection with HS rivets, in order to investigate its fatigue feature and deterioration mechanism. At first, based on the load transfer feature of ring flange connections, model fatigue tests of twelve specimens were conducted after the static tensile test. The tested twelve specimens included six with HS rivets and six with HS bolts. Further, multi-scale finite element analysis was performed with refined models, in accordance with the local strain-based SWT fatigue evaluation approach. According to the result, the first engaged thread of rivets/bolts is prone to fatigue failure in both the two types of specimens. Under the 2 million loading cycles, the equivalent fatigue strength of HS rivet specimens shows a mean value of 68.9 MPa, which increases by 32.2% compared with the value (52.1 MPa) of HS bolt specimens. The stress concentration at the root of threads could be effectively mitigated due to the flattened thread and increased contact area of inner-outer threads between the sleeve ring and HS rivet. Consequently, the fatigue performance of HS rivets is enhanced. As above, this study suggested that in the fatigue check of ring-flange connections with structural HS rivets, the fatigue strength of HS rivets could be determined as FAT 56, in accordance with the power constant of m = 3.