Study on pre-tightening force formation and tightening process characteristics of self-locking nut

The self-locking nut has good seismic and anti-loosening performance and is widely used in the assembly of aero-engine rotor structures. The control accuracy of the pre-tightening force is crucial to the performance of the engine. However, the influence of the self-locking nut on the tightening process is less studied at present. First, the tightening process of the self-locking nut under the machining error is analysed, and the theory and error analysis of the bolt assembly process are carried out. The self-locking nut is closed by means of node offset. The influence of the self-locking nut on the tightening process is simulated and analysed. The results show that the closing nut makes the stress redistribution of the thread and the end face of the nut, from uniform distribution to symmetrical distribution, resulting in stress concentration. Finally, the single bolt tightening test is carried out to explore the influence of the number of tightening cycles on the tightening process parameters, and to provide guidance for the existing tightening process.