螺栓-螺母连接结构卡滞机理及影响因素研究

Seizure is a failure mode that results in threaded fasteners losing their ease of disassembly. Due to the difficulties associated with laboratory replication and observation of seizure failure, there has been limited in-depth research on this topic. A replication experimental methodology for the seizure phenomenon observed in bolt-nut structures is presented in this paper. The plastic deformation of internal and external threads and the variations in loading parameters such as torque and preload during seizure are summarized, and two typical modes of seizure failure are identified. The concept of seizure life is introduced, providing an evaluation criterion for the anti-seizure performance of threaded pairs. Seizure life curves for bolt-nut structures under different materials, pitches, and lubrication conditions are determined. The influences of material, pitch, and lubrication on the anti-seizure performance of threaded pairs are investigated. A refined finite element model of the bolt-nut structure is established to computationally analyze the mechanisms through which these factors affect the anti-seizure performance. The results indicate that, under certain loading conditions, the greater the yield strength of the material used in the threaded pair, the longer the seizure life, the smaller the thread pitch, the shorter the seizure life. Additionally, the anti-seizure performance of the threaded pair is significantly enhanced by lubrication. The excessive ratio of thread plastic deformation to the clearance between internal and external threads is a significant cause of seizure, while other factors such as material, pitch, and lubrication status indirectly influence the seizure life of the thread pair by affecting this ratio.